CN117443441A - Catalyst for preparing low-carbon olefin from waste plastics and preparation method and application thereof - Google Patents
Catalyst for preparing low-carbon olefin from waste plastics and preparation method and application thereof Download PDFInfo
- Publication number
- CN117443441A CN117443441A CN202210847816.2A CN202210847816A CN117443441A CN 117443441 A CN117443441 A CN 117443441A CN 202210847816 A CN202210847816 A CN 202210847816A CN 117443441 A CN117443441 A CN 117443441A
- Authority
- CN
- China
- Prior art keywords
- catalyst
- molecular sieve
- waste plastics
- oxide
- sba
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
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- 239000003054 catalyst Substances 0.000 title claims abstract description 180
- 229920003023 plastic Polymers 0.000 title claims abstract description 129
- 239000004033 plastic Substances 0.000 title claims abstract description 129
- 239000002699 waste material Substances 0.000 title claims abstract description 125
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 76
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 title claims abstract description 76
- 238000002360 preparation method Methods 0.000 title claims abstract description 56
- 239000002808 molecular sieve Substances 0.000 claims abstract description 161
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims abstract description 161
- 239000002243 precursor Substances 0.000 claims abstract description 117
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 79
- 239000010703 silicon Substances 0.000 claims abstract description 79
- 238000000465 moulding Methods 0.000 claims abstract description 65
- 238000006243 chemical reaction Methods 0.000 claims abstract description 63
- 229910021536 Zeolite Inorganic materials 0.000 claims abstract description 51
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 claims abstract description 51
- 239000010457 zeolite Substances 0.000 claims abstract description 51
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 35
- 238000000034 method Methods 0.000 claims description 75
- 239000011148 porous material Substances 0.000 claims description 60
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 50
- 239000007864 aqueous solution Substances 0.000 claims description 43
- 150000001336 alkenes Chemical class 0.000 claims description 39
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 38
- 239000000843 powder Substances 0.000 claims description 34
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 32
- 238000001035 drying Methods 0.000 claims description 29
- 239000000377 silicon dioxide Substances 0.000 claims description 29
- VXAUWWUXCIMFIM-UHFFFAOYSA-M aluminum;oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Al+3] VXAUWWUXCIMFIM-UHFFFAOYSA-M 0.000 claims description 24
- 238000002156 mixing Methods 0.000 claims description 21
- 230000002378 acidificating effect Effects 0.000 claims description 18
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims description 17
- 239000004327 boric acid Substances 0.000 claims description 17
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 16
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 16
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 15
- 229910017604 nitric acid Inorganic materials 0.000 claims description 15
- 150000003839 salts Chemical class 0.000 claims description 13
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 12
- 239000001913 cellulose Substances 0.000 claims description 10
- 229920002678 cellulose Polymers 0.000 claims description 10
- 241000219782 Sesbania Species 0.000 claims description 9
- 229910052810 boron oxide Inorganic materials 0.000 claims description 9
- JKWMSGQKBLHBQQ-UHFFFAOYSA-N diboron trioxide Chemical compound O=BOB=O JKWMSGQKBLHBQQ-UHFFFAOYSA-N 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 claims description 9
- 229910052751 metal Inorganic materials 0.000 claims description 9
- 239000002184 metal Substances 0.000 claims description 9
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims description 8
- 239000000292 calcium oxide Substances 0.000 claims description 8
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 8
- 229910000420 cerium oxide Inorganic materials 0.000 claims description 8
- 238000001125 extrusion Methods 0.000 claims description 8
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 claims description 8
- 239000011787 zinc oxide Substances 0.000 claims description 8
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 7
- 239000000395 magnesium oxide Substances 0.000 claims description 7
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 7
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 7
- 229910052698 phosphorus Inorganic materials 0.000 claims description 7
- 239000011574 phosphorus Substances 0.000 claims description 7
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 claims description 6
- MRELNEQAGSRDBK-UHFFFAOYSA-N lanthanum(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[La+3].[La+3] MRELNEQAGSRDBK-UHFFFAOYSA-N 0.000 claims description 6
- IATRAKWUXMZMIY-UHFFFAOYSA-N strontium oxide Chemical compound [O-2].[Sr+2] IATRAKWUXMZMIY-UHFFFAOYSA-N 0.000 claims description 6
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 4
- QVQLCTNNEUAWMS-UHFFFAOYSA-N barium oxide Chemical compound [Ba]=O QVQLCTNNEUAWMS-UHFFFAOYSA-N 0.000 claims description 4
- 229910001593 boehmite Inorganic materials 0.000 claims description 3
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 claims description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 2
- 229910052684 Cerium Inorganic materials 0.000 claims description 2
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 2
- 239000002202 Polyethylene glycol Substances 0.000 claims description 2
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 2
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N ZrO2 Inorganic materials O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims description 2
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims description 2
- 229910000287 alkaline earth metal oxide Inorganic materials 0.000 claims description 2
- 150000001342 alkaline earth metals Chemical class 0.000 claims description 2
- 229940024546 aluminum hydroxide gel Drugs 0.000 claims description 2
- SMYKVLBUSSNXMV-UHFFFAOYSA-K aluminum;trihydroxide;hydrate Chemical compound O.[OH-].[OH-].[OH-].[Al+3] SMYKVLBUSSNXMV-UHFFFAOYSA-K 0.000 claims description 2
- 229910052788 barium Inorganic materials 0.000 claims description 2
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 claims description 2
- 229910052791 calcium Inorganic materials 0.000 claims description 2
- 239000011575 calcium Substances 0.000 claims description 2
- 229910001679 gibbsite Inorganic materials 0.000 claims description 2
- 229910052746 lanthanum Inorganic materials 0.000 claims description 2
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims description 2
- 229910052749 magnesium Inorganic materials 0.000 claims description 2
- 239000011777 magnesium Substances 0.000 claims description 2
- 229910052755 nonmetal Inorganic materials 0.000 claims description 2
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 claims description 2
- 229920002401 polyacrylamide Polymers 0.000 claims description 2
- 229920001223 polyethylene glycol Polymers 0.000 claims description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 2
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 2
- 229910001404 rare earth metal oxide Inorganic materials 0.000 claims description 2
- 150000002910 rare earth metals Chemical class 0.000 claims description 2
- 229910052712 strontium Inorganic materials 0.000 claims description 2
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 claims description 2
- 229910052723 transition metal Inorganic materials 0.000 claims description 2
- 229910000314 transition metal oxide Inorganic materials 0.000 claims description 2
- 150000003624 transition metals Chemical class 0.000 claims description 2
- 229910052725 zinc Inorganic materials 0.000 claims description 2
- 239000011701 zinc Substances 0.000 claims description 2
- 229910052726 zirconium Inorganic materials 0.000 claims description 2
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims 1
- 238000004064 recycling Methods 0.000 abstract description 9
- 239000000126 substance Substances 0.000 abstract description 9
- 239000002994 raw material Substances 0.000 abstract description 8
- 239000002861 polymer material Substances 0.000 abstract description 2
- 230000008569 process Effects 0.000 description 29
- 239000012265 solid product Substances 0.000 description 26
- 239000000243 solution Substances 0.000 description 22
- 238000011156 evaluation Methods 0.000 description 21
- 238000003756 stirring Methods 0.000 description 20
- 230000000052 comparative effect Effects 0.000 description 19
- 239000012153 distilled water Substances 0.000 description 19
- 239000000203 mixture Substances 0.000 description 17
- 230000009257 reactivity Effects 0.000 description 16
- 239000000047 product Substances 0.000 description 15
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 13
- 229910004298 SiO 2 Inorganic materials 0.000 description 11
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 11
- 238000001354 calcination Methods 0.000 description 11
- 239000002904 solvent Substances 0.000 description 10
- ONDPHDOFVYQSGI-UHFFFAOYSA-N zinc nitrate Chemical compound [Zn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ONDPHDOFVYQSGI-UHFFFAOYSA-N 0.000 description 10
- 238000005336 cracking Methods 0.000 description 9
- 238000005516 engineering process Methods 0.000 description 9
- 239000011230 binding agent Substances 0.000 description 8
- ZCCIPPOKBCJFDN-UHFFFAOYSA-N calcium nitrate Chemical compound [Ca+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ZCCIPPOKBCJFDN-UHFFFAOYSA-N 0.000 description 8
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium(3+);trinitrate Chemical compound [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 description 8
- YIXJRHPUWRPCBB-UHFFFAOYSA-N magnesium nitrate Chemical compound [Mg+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O YIXJRHPUWRPCBB-UHFFFAOYSA-N 0.000 description 8
- 238000002441 X-ray diffraction Methods 0.000 description 7
- 230000008901 benefit Effects 0.000 description 7
- 230000003197 catalytic effect Effects 0.000 description 6
- 239000008367 deionised water Substances 0.000 description 6
- 229910021641 deionized water Inorganic materials 0.000 description 6
- 239000000499 gel Substances 0.000 description 6
- 238000001228 spectrum Methods 0.000 description 6
- 238000004227 thermal cracking Methods 0.000 description 6
- 238000005406 washing Methods 0.000 description 6
- 238000004523 catalytic cracking Methods 0.000 description 5
- 239000003795 chemical substances by application Substances 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- 230000007062 hydrolysis Effects 0.000 description 5
- 238000006460 hydrolysis reaction Methods 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 238000005520 cutting process Methods 0.000 description 4
- 238000009792 diffusion process Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000002736 nonionic surfactant Substances 0.000 description 4
- 239000000376 reactant Substances 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 4
- KKCBUQHMOMHUOY-UHFFFAOYSA-N sodium oxide Chemical compound [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 4
- 229910001948 sodium oxide Inorganic materials 0.000 description 4
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- -1 ethylene, propylene Chemical group 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 238000010304 firing Methods 0.000 description 3
- 238000001027 hydrothermal synthesis Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000000051 modifying effect Effects 0.000 description 3
- 239000010413 mother solution Substances 0.000 description 3
- 230000007935 neutral effect Effects 0.000 description 3
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 3
- 241000196324 Embryophyta Species 0.000 description 2
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 2
- 230000004913 activation Effects 0.000 description 2
- 239000002390 adhesive tape Substances 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 2
- 239000000295 fuel oil Substances 0.000 description 2
- 230000001788 irregular Effects 0.000 description 2
- 238000011068 loading method Methods 0.000 description 2
- 239000013335 mesoporous material Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 235000019353 potassium silicate Nutrition 0.000 description 2
- 238000000197 pyrolysis Methods 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 238000001988 small-angle X-ray diffraction Methods 0.000 description 2
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 2
- DHEQXMRUPNDRPG-UHFFFAOYSA-N strontium nitrate Chemical compound [Sr+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O DHEQXMRUPNDRPG-UHFFFAOYSA-N 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- LFQCEHFDDXELDD-UHFFFAOYSA-N tetramethyl orthosilicate Chemical compound CO[Si](OC)(OC)OC LFQCEHFDDXELDD-UHFFFAOYSA-N 0.000 description 2
- 125000000383 tetramethylene group Chemical group [H]C([H])([*:1])C([H])([H])C([H])([H])C([H])([H])[*:2] 0.000 description 2
- 238000004438 BET method Methods 0.000 description 1
- IAYPIBMASNFSPL-UHFFFAOYSA-N Ethylene oxide Chemical compound C1CO1 IAYPIBMASNFSPL-UHFFFAOYSA-N 0.000 description 1
- 241000282414 Homo sapiens Species 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- GOOHAUXETOMSMM-UHFFFAOYSA-N Propylene oxide Chemical compound CC1CO1 GOOHAUXETOMSMM-UHFFFAOYSA-N 0.000 description 1
- 239000004115 Sodium Silicate Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000007233 catalytic pyrolysis Methods 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 238000001833 catalytic reforming Methods 0.000 description 1
- ZMIGMASIKSOYAM-UHFFFAOYSA-N cerium Chemical compound [Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce] ZMIGMASIKSOYAM-UHFFFAOYSA-N 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000006356 dehydrogenation reaction Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000000921 elemental analysis Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000002737 fuel gas Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 239000002638 heterogeneous catalyst Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 239000011147 inorganic material Substances 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- FYDKNKUEBJQCCN-UHFFFAOYSA-N lanthanum(3+);trinitrate Chemical compound [La+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O FYDKNKUEBJQCCN-UHFFFAOYSA-N 0.000 description 1
- 229920002521 macromolecule Polymers 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000012229 microporous material Substances 0.000 description 1
- 238000002715 modification method Methods 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000005191 phase separation Methods 0.000 description 1
- 239000013502 plastic waste Substances 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 238000011085 pressure filtration Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000004445 quantitative analysis Methods 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 238000002383 small-angle X-ray diffraction data Methods 0.000 description 1
- 235000019795 sodium metasilicate Nutrition 0.000 description 1
- 239000004317 sodium nitrate Substances 0.000 description 1
- 235000010344 sodium nitrate Nutrition 0.000 description 1
- 229910052911 sodium silicate Inorganic materials 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
- 239000003440 toxic substance Substances 0.000 description 1
- 229920000428 triblock copolymer Polymers 0.000 description 1
- 238000003828 vacuum filtration Methods 0.000 description 1
- 238000004736 wide-angle X-ray diffraction Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/005—Mixtures of molecular sieves comprising at least one molecular sieve which is not an aluminosilicate zeolite, e.g. from groups B01J29/03 - B01J29/049 or B01J29/82 - B01J29/89
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C4/00—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms
- C07C4/02—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms by cracking a single hydrocarbon or a mixture of individually defined hydrocarbons or a normally gaseous hydrocarbon fraction
- C07C4/06—Catalytic processes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
- B01J2229/10—After treatment, characterised by the effect to be obtained
- B01J2229/18—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/03—Catalysts comprising molecular sieves not having base-exchange properties
- B01J29/0308—Mesoporous materials not having base exchange properties, e.g. Si-MCM-41
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
- B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- B01J29/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
- B01J29/7038—MWW-type, e.g. MCM-22, ERB-1, ITQ-1, PSH-3 or SSZ-25
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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Abstract
The invention relates to the field of catalysts and the field of polymer material recycling, and discloses a catalyst for preparing low-carbon olefin from waste plastics, a preparation method and application thereof. The catalyst for preparing the low-carbon olefin from the waste plastics comprises a molding precursor and a modified oxide loaded on the molding precursor, wherein the molding precursor comprises an MCM-22 zeolite molecular sieve, an SBA-15 all-silicon mesoporous molecular sieve and alumina, the content of the molding precursor is 90-98 wt% and the content of the modified oxide is 2-10 wt% based on the total weight of the catalyst for preparing the low-carbon olefin from the waste plastics. The catalyst of the invention solves the problem of recycling waste plastics and increases the yield of important chemical raw materials of low-carbon olefin in the reaction of directly converting waste plastics into low-carbon olefin.
Description
Technical Field
The invention relates to the field of catalysts and the field of polymer material recycling, in particular to a catalyst for preparing low-carbon olefin from waste plastics, a preparation method and application thereof.
Background
Plastic products are widely used in various fields worldwide. However, plastics are difficult to degrade naturally, and conventional landfill techniques, although they are low in investment and simple to operate, can encroach on a large amount of land, causing land pollution. Although the incineration technology can realize the reduction requirement and recover part of energy, the process is easy to release a large amount of hydrocarbons, nitrides, sulfides and highly toxic substances, which directly threatens the health of human beings and ecological environment. Therefore, the recovery and high-value utilization of waste plastics are widely regarded as a measure for saving energy and protecting environment in all countries of the world. The waste plastic recycling method mainly comprises the technologies of classified recycling, monomer raw material preparation, clean fuel oil production, power generation and the like.
In the prior art, the chemical recycling scheme of waste plastics is mainly waste plastic cracking technology. Waste plastic pyrolysis includes three basic methods, namely: thermal cracking (one-stage process), catalytic cracking (one-stage process) and thermal cracking-catalytic modification (two-stage process). The earliest waste plastic cracking technology developed was thermal cracking technology. The technology refers to a thermal conversion process of performing thermochemical decomposition reaction under the condition of high Wen Jue oxygen to convert macromolecular organic matters in waste plastic products into substances such as liquid matters with small molecular mass, fuel gas, coke and the like. The reaction temperature of the process is generally controlled between 350 and 900 ℃. If the catalyst is added in the thermal cracking process, the catalytic thermal cracking technology is adopted, so that the cracking temperature can be reduced, and the product performance can be improved. The improvement of thermal cracking-catalytic modification method is that after waste plastics are thermally cracked, the catalyst is used to make catalytic modification on the cracked gas.
The pyrolysis technology has wide flexibility in waste plastic treatment and good energy recovery, and is one of waste plastic treatment technologies with wide application prospects. In the prior art, the products produced by the one-step thermal cracking method and the one-step catalytic cracking method are mainly fuel oil, and only a small amount of low-carbon olefin (ethylene, propylene and butylene) can be obtained. If a large amount of low-carbon olefins are required, a two-stage process using a thermal cracking-catalytic reforming process is required.
It is therefore an important research direction for plastic waste treatment to explore a new chemical recycling process to produce a clean and high quality end product.
Disclosure of Invention
The invention aims to solve the problem of low-carbon olefin content in the catalytic cracking reaction product of the plastic in the prior art, and provides a catalyst for preparing low-carbon olefin from waste plastic, a preparation method and application thereof.
In order to achieve the above object, a first aspect of the present invention provides a catalyst for producing low-carbon olefin from waste plastics, wherein the catalyst for producing low-carbon olefin from waste plastics comprises a molding precursor and a modified oxide supported on the molding precursor, the molding precursor comprises an MCM-22 zeolite molecular sieve, an SBA-15 all-silicon mesoporous molecular sieve and alumina, and the content of the molding precursor is 90 to 98 wt% and the content of the modified oxide is 2 to 10 wt% based on the total weight of the catalyst for producing low-carbon olefin from waste plastics.
The second aspect of the invention provides a preparation method of a catalyst for preparing light olefins from waste plastics, wherein the preparation method comprises the following steps:
(1) Mixing the molding precursor with an aqueous solution of metal salt, performing a first contact reaction, and performing water removal and first drying treatment to obtain a catalyst intermediate; the molding precursor comprises an MCM-22 zeolite molecular sieve, an SBA-15 all-silicon mesoporous molecular sieve and alumina;
(2) And mixing the catalyst intermediate with an acidic aqueous solution, performing a second contact reaction, and performing water removal, second drying and roasting treatment to obtain the catalyst for preparing the low-carbon olefin from the waste plastics.
The third aspect of the invention provides a catalyst for preparing light olefins from waste plastics prepared by the preparation method.
The fourth aspect of the invention provides an application of the catalyst for preparing the low-carbon olefin from the waste plastics in a reaction for preparing the low-carbon olefin from the waste plastics by direct conversion.
Through the technical scheme, the technical scheme of the invention has the following advantages:
(1) The catalyst for preparing the low-carbon olefin from the waste plastics has the advantages of easily available raw materials, simple preparation method and process, easily controlled conditions and good product repeatability.
(2) The catalyst for preparing the low-carbon olefin from the waste plastics provided by the invention comprises the zeolite molecular sieve with certain acidity on the surface and the mesoporous material with larger pore diameter, has stable structure and good high temperature resistance, and is beneficial to the diffusion of raw materials and product molecules in the cracking reaction process; in addition, the molding precursor comprises alumina, molding is utilized, and the molded sample has good strength.
(3) The catalyst for preparing the low-carbon olefin from the waste plastics can convert the waste plastics into the low-carbon olefin in one step when being used for the reaction for preparing the low-carbon olefin from the waste plastics by direct conversion, and is a novel method for chemically recycling the waste plastics. Solves the problem of recycling waste plastics, increases the yield of important chemical raw materials, namely low-carbon olefin, and has good economic benefit.
(4) The catalyst for preparing the low-carbon olefin from the waste plastics is used for the reaction for preparing the low-carbon olefin from the waste plastics by direct conversion, and has the advantages of mild process conditions, easy operation and low requirements on reaction devices.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate the invention and together with the description serve to explain, without limitation, the invention. In the drawings:
FIG. 1 is a wide-angle X-ray diffraction (XRD) spectrum of a catalyst A for preparing light olefins from waste plastics in example 1;
FIG. 2 is a small angle X-ray diffraction (XRD) spectrum of the catalyst A for preparing light olefins from waste plastics of example 1.
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
As described above, the first aspect of the present invention provides a catalyst for producing low-carbon olefin from waste plastics, wherein the catalyst for producing low-carbon olefin from waste plastics comprises a molding precursor and a modified oxide supported on the molding precursor, the molding precursor comprises MCM-22 zeolite molecular sieve, SBA-15 all-silicon mesoporous molecular sieve and alumina, and the content of the molding precursor is 90 to 98 wt% and the content of the modified oxide is 2 to 10 wt% based on the total weight of the catalyst for producing low-carbon olefin from waste plastics.
The inventors of the present invention found that: in the prior art, no process for producing low-carbon olefin (including ethylene, propylene and butylene) by directly catalytically cracking waste plastics exists, and the aim of the invention is to solve the problem. According to the knowledge of the inventor on the physical and chemical properties of the heterogeneous catalyst, the catalyst for directly preparing the low-carbon olefin by the catalytic pyrolysis of the waste plastics has certain acidity and better hydrothermal stability. Based on the above requirements, the zeolite molecular sieve with stable framework structure and certain acidity is very suitable to be used as the main component of the catalyst for preparing low-carbon olefin from waste plastics. However, because zeolite molecular sieves have smaller pore sizes (typically between 0.4 and 0.7 nm), the molecular weight of the waste plastic product is larger and the molecular chains are longer. In the cracking reaction process of waste plastic products, reactant molecules and product molecules with larger sizes are difficult to diffuse between narrow pore channels, so that the contact between the reactant and an active center is influenced, side reactions such as deep dehydrogenation and the like are easy to occur, and the performance of the catalyst is reduced. For example: the MCM-22 zeolite molecular sieve has two independent and unconnected pore structures, wherein the inner pore is a 10-membered ring two-dimensional sinusoidal pore, and the aperture is 0.4 multiplied by 0.6nm; the interlayer pore canal is a 12-membered ring super cage, and the aperture is 0.7x0.8 nm; the super cage opening is a 10 membered ring of 0.4X0.5 nm. Compared with zeolite molecular sieve, the SBA-15 all-silicon mesoporous molecular sieve material has large pore canal size and large pore volume, and is very suitable for the catalytic reaction with macromolecules. However, the surface acidity of the all-silicon mesoporous molecular sieve material is extremely weak, and the material is not suitable for being used as a catalyst for catalyzing waste plastic cracking reaction alone. The inventor of the invention finds that if the structural advantage of the all-silicon mesoporous inorganic material and the surface acid center of the zeolite molecular sieve are comprehensively utilized when the low-carbon olefin catalyst prepared from waste plastics and waste plastics is developed and researched, a certain amount of SBA-15 all-silicon mesoporous molecular sieve and MCM-22 zeolite molecular sieve are mixed and modified, and the catalyst is used as a main component of the catalyst for the cracking reaction of waste plastics, so that the activity of the low-carbon olefin catalyst prepared from waste plastics can be effectively improved, and the selectivity of the low-carbon olefin can be increased.
According to the present invention, preferably, the molding precursor is contained in an amount of 92 to 97% by weight and the modified oxide is contained in an amount of 3 to 8% by weight, based on the total weight of the catalyst for producing light olefins from waste plastics; more preferably, the molding precursor is contained in an amount of 93 to 96 wt% and the modified oxide is contained in an amount of 4 to 7 wt% based on the total weight of the catalyst for producing light olefins from waste plastics. In the invention, the prepared catalyst for preparing the low-carbon olefin by using the waste plastics can have better catalytic activity and higher low-carbon olefin selectivity when being used for the reaction of preparing the low-carbon olefin by directly converting the waste plastics by adopting the content of the specific components.
According to the invention, the content of the MCM-22 zeolite molecular sieve is 34-55 wt%, the content of the SBA-15 all-silicon mesoporous molecular sieve is 27-58 wt% and the content of the alumina is 8-18 wt% based on the total weight of the molding precursor; preferably, the MCM-22 zeolite molecular sieve is present in an amount of 37 to 51 wt%, the SBA-15 all-silica mesoporous molecular sieve is present in an amount of 34 to 53 wt%, and the alumina is present in an amount of 10 to 15 wt%, based on the total weight of the shaped precursor. More preferably, the MCM-22 zeolite molecular sieve is present in an amount of 41 to 48 wt%, the SBA-15 all-silica mesoporous molecular sieve is present in an amount of 40 to 45 wt%, and the alumina is present in an amount of 12 to 14 wt%, based on the total weight of the shaped precursor. In the invention, the prepared catalyst for preparing the low-carbon olefin by using the waste plastics can have better catalytic activity and higher low-carbon olefin selectivity when being used for the reaction of preparing the low-carbon olefin by directly converting the waste plastics by adopting the content of the specific components.
According to the invention, the specific surface area of the MCM-22 zeolite molecular sieve is 400-600m 2 Per gram, pore volume of 0.4-0.7cm 3 /g; preferably, the specific surface area of the MCM-22 zeolite molecular sieve is 450-500m 2 Per gram, pore volume of 0.5-0.6cm 3 And/g. In the present invention, the MCM-22 zeolite molecular sieve may be MCM-22 molecular sieve (silicon to aluminum molar ratio SiO) of NKF-10 type purchased from Nanka university catalyst works 2 /Al 2 O 3 30, a specific surface area of 472m 2 Per gram, pore volume of 0.5cm 3 /g)。
According to the invention, the specific surface area of the SBA-15 all-silicon mesoporous molecular sieve is 650-1100m 2 /g; pore size (average pore diameter) of 5-8nm and pore volume of 1.2-1.6cm 3 /g; preferably, the specific surface area of the SBA-15 all-silicon mesoporous molecular sieve is 892-967m 2 /g; pore size (average pore diameter) of 6.4-7nm and pore volume of 1.2-1.4cm 3 And/g. In the invention, the SBA-15 full-silicon mesoporous molecular sieve with the specific parameters is adopted, so that the prepared catalyst for preparing the low-carbon olefin by using the waste plastics has better catalytic activity and higher selectivity when being used for the reaction for preparing the low-carbon olefin by directly converting the waste plastics. In the invention, the SBA-15 full-silicon mesoporous molecular sieve can be prepared by adopting a conventional method, and the SBA-15 full-silicon mesoporous molecular sieve can also be prepared by adopting the following steps:
(a) Under the condition of preparing an adhesive tape piece by hydrolysis, mixing a template solvent, a silicon source and dilute hydrochloric acid to prepare a gel mixture;
(b) And crystallizing the gel mixture.
(c) And carrying out solid-liquid separation, washing, drying and roasting treatment on the crystallized product to obtain the SBA-15 all-silicon mesoporous molecular sieve.
Specifically, under the condition of preparing an adhesive tape by hydrolysis, mixing a template agent, the silicon source and the dilute hydrochloric acid to obtain a gel mixture; wherein the concentration of the dilute hydrochloric acid is 1-2mol/L; transferring the gel mixture into a polytetrafluoroethylene-lined reaction kettle, and crystallizing for 10-40 hours at 80-120 ℃; separating the crystallized product, washing with deionized water, drying the crystallized solid product in 70-120 deg.c for 3-10 hr, and roasting at 450-650 deg.c for 3-12 hr to obtain the full silicon SBA-15 mesoporous molecular sieve.
In the preparation method of the SBA-15 all-silicon mesoporous molecular sieve, the template agent comprises the following steps: the silicon source: the weight ratio of the dilute hydrochloric acid is 1: (0.5-5.0): (5-100), preferably 1: (1.5-2.5): (15-50).
In the preparation method of the SBA-15 all-silicon mesoporous molecular sieve, a template agent used for synthesizing the SBA-15 molecular sieve conventionally can be adopted, for example, a nonionic surfactant can be adopted, and the template agent is preferably polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer; wherein the template agent has a general formula of EO a PO b EO a Wherein a has a value of 5 to 140, b has a value of 30 to 100, EO is an abbreviation for ethylene oxide, and PO is an abbreviation for propylene oxide; particularly preferred is P123 (EO 20 PO 70 EO 20 ). In addition, P123 is a trade name, which is commercially available from Sigma-Aldrich Chemistry.
In the preparation method of the SBA-15 full-silicon mesoporous molecular sieve, the silicon source is an organic silicon source and/or an inorganic silicon source, wherein the organic silicon source is organic silicate, preferably methyl orthosilicate and/or ethyl orthosilicate; the inorganic silicon source is an inorganic silicon-containing compound, preferably one or more of water glass, sodium metasilicate and silica sol.
In the preparation method of the SBA-15 all-silicon mesoporous molecular sieve, the preparation method has no special requirement on the hydrolysis gel preparation conditions, and under the preferred condition, the hydrolysis gel preparation strip comprises the hydrolysis temperature of 20-60 ℃, more preferably 30-50 ℃; the time is 12 to 36 hours, more preferably 18 to 30 hours.
In the preparation method of the SBA-15 all-silicon mesoporous molecular sieve, the crystallization conditions comprise: the temperature is 80-120 ℃ and the time is 10-40h.
In the preparation method of the SBA-15 all-silicon mesoporous molecular sieve, no special requirement is imposed on the solid-liquid two-phase separation process, and the separation method can be a separation mode known in the art, including gravity filtration, pressure filtration, vacuum filtration or centrifugal filtration. Preferably, the separation process specifically includes: vacuum-pumping the bottom of the funnel by using a suction bottle or filtering by using a centrifugal filter.
In the above-mentioned preparation method of SBA-15 all-silicon mesoporous molecular sieve, the method for washing the solid product is not particularly required, for example: the solid product may be washed with deionized water, the volume ratio of deionized water to solid product may be 5-20, and the number of washes may be 2-8.
In the preparation method of the SBA-15 all-silicon mesoporous molecular sieve, the drying conditions comprise: the temperature may be 60-150deg.C, preferably 70-120deg.C; the time may be 2 to 30 hours, preferably 3 to 10 hours.
In the preparation method of the SBA-15 all-silicon mesoporous molecular sieve, the condition of the roasting treatment can be 400-700 ℃, preferably 450-650 ℃; the time is 2-40h, preferably 3-12h.
According to the present invention, the method for preparing the molding precursor comprises: in the presence of an acidic aqueous solution, mixing an MCM-22 zeolite molecular sieve, an all-silicon SBA-15 mesoporous molecular sieve, an alumina precursor and an extrusion aid, performing extrusion molding, and performing drying and roasting treatment to obtain a molding precursor.
In the above method for producing a molded precursor, the acidic aqueous solution is one or more selected from the group consisting of dilute nitric acid, dilute hydrochloric acid, dilute phosphoric acid and dilute sulfuric acid, preferably dilute nitric acid; the concentration of the acidic aqueous solution may be 1 to 30%, preferably 2 to 15%.
The above-mentionedIn the preparation method of the molding precursor of (2), the alumina precursor is selected from one or more of pseudo-boehmite, aluminum hydroxide gel, alumina sol, gibbsite and boehmite; preferably pseudo-boehmite. In the present invention, the pseudo-boehmite may be commercially available or prepared, and in the present invention, specifically, the pseudo-boehmite comprises: german original imported pseudo-boehmite powder (available from Beijing Asia Taiao chemical auxiliary agent Co., ltd., specific surface area of 241 m) 2 Per gram, pore volume of 0.53cm 3 Per g), pseudo-boehmite powder (model P-DF-09-LSi, manufactured by Shandong aluminum company Limited liability company, having a specific surface area of 286m 2 Per gram, pore volume of 1.08cm 3 Per g) and macroporous pseudo-boehmite powder (manufactured by Zibo constant Ji Fen New Material Co., ltd., specific surface area: 327 m) of type PB-0101 2 Per gram, pore volume of 1.02cm 3 /g).
In the above method for preparing the molding precursor, the extrusion aid is one or more selected from cellulose, sesbania powder, polyacrylamide, polyvinyl alcohol, glycerol and polyethylene glycol, preferably cellulose or sesbania powder.
In the preparation method of the molding precursor, the weight ratio of the MCM-22 molecular sieve to the all-silicon SBA-15 mesoporous molecular sieve to the alumina precursor to the extrusion aid to the acidic aqueous solution is 1: (0.4-2.0): (0.2-0.6): (0.02-0.16): (0.8-1.6), preferably 1: (0.6-1.5): (0.3-0.5): (0.04-0.12): (1.0-1.4).
In the above method for producing a molded precursor, the drying conditions include: the temperature is 60-140 ℃ and the time is 5-20h.
In the above method for producing a molded precursor, the firing conditions include: the temperature is 450-650 ℃, preferably 500-600 ℃; the time is 2-30 hours, preferably 5-16 hours.
According to the invention, the shaped precursor may be spherical, granular, bar-like, cylindrical, toothed-spherical or clover-shaped.
According to the present invention, the modified oxide is selected from one or more of alkaline earth metal oxide, transition metal oxide, rare earth metal oxide and nonmetal oxide; preferably, the modified oxide is selected from one or more of magnesium oxide, calcium oxide, strontium oxide, barium oxide, zinc oxide, cerium oxide, lanthanum oxide, zirconium dioxide, phosphorus-containing oxide and boron oxide. In the present invention, the specific modified oxide selected from the present invention has the advantage of improving the electron distribution on the surface of the molecular sieve and selectively covering a part of the excessively strong acid center, so that the surface characteristics of the catalyst are more suitable for the waste plastic cracking reaction.
According to the invention, the specific surface area of the catalyst for preparing the low-carbon olefin from the waste plastics is 400-800m 2 Per gram, pore volume of 0.5-1.1cm 3 /g; preferably, the specific surface area of the catalyst is 532-675m 2 Per gram, pore volume of 0.7-0.9cm 3 And/g. In the present invention, the specific surface area and the pore volume of the mesoporous material are large, but the specific surface area and the pore volume of the molded product after being mixed with the zeolite molecular sieve and the binder are reduced.
The second aspect of the invention provides a preparation method of a catalyst for preparing light olefins from waste plastics, wherein the preparation method comprises the following steps:
(1) Mixing the molding precursor with an aqueous solution of metal salt, performing a first contact reaction, and performing water removal and first drying treatment to obtain a catalyst intermediate; the molding precursor comprises an MCM-22 zeolite molecular sieve, an SBA-15 all-silicon mesoporous molecular sieve and alumina;
(2) And mixing the catalyst intermediate with an acidic aqueous solution, performing a second contact reaction, and performing water removal, second drying and roasting treatment to obtain the catalyst for preparing the low-carbon olefin from the waste plastics.
According to the present invention, in step (1), the metal salt is selected from inorganic salts containing alkaline earth metals, transition metals and rare earth metals; preferably, the modified oxide precursor is selected from the group consisting of inorganic salts containing magnesium, calcium, strontium, barium, zinc, cerium, lanthanum and zirconium;
According to the invention, in step (1), the aqueous metal salt concentration is 1-20%, preferably 2-10%;
according to the present invention, in step (1), the conditions of the first contact reaction include: the temperature is 20-90 ℃ and the time is 0.5-20h;
according to the invention, in step (1), the weight ratio of the shaping precursor to the aqueous solution of the metal salt is 1: (2-30), preferably 1: (5-20).
According to the present invention, in step (1), the first drying condition includes: the temperature is 60-120 ℃; the time is 3-12h.
According to the invention, in step (2), the acidic aqueous solution is selected from one or more of phosphoric acid or boric acid;
according to the invention, in step (2), the acidic aqueous solution has a concentration of 0.5-10%, preferably 1-5%;
according to the invention, in step (2), the weight ratio of the catalyst intermediate to the acidic aqueous solution is 1: (1-20), preferably 1: (3-15).
According to the present invention, in step (2), the conditions of the second contact reaction include: the temperature is 20-90 ℃ and the time is 0.5-10h.
According to the present invention, in step (2), the second drying condition includes: the temperature is 80-150 ℃; the time is 3-30h.
According to the present invention, in step (2), the conditions for firing include: the temperature may be 450-650 ℃, preferably 500-600 ℃; the time may be 2 to 20 hours, preferably 3 to 10 hours.
The third aspect of the invention provides a catalyst for preparing light olefins from waste plastics prepared by the preparation method.
The fourth aspect of the invention provides an application of the catalyst for preparing the low-carbon olefin from the waste plastics in the reaction for preparing the low-carbon olefin from the waste plastics by direct conversion.
According to the invention, the application method of the catalyst comprises the following steps: the waste plastic powder is contacted with the catalyst for preparing the low-carbon olefin from the waste plastic to react.
In the invention, the conditions for contacting the waste plastic powder with the catalyst for preparing the low-carbon olefin from the waste plastic comprise: the temperature of contact may be 420-580 ℃, preferably 450-540 ℃; the contact pressure may be 0.01-1.0Mpa, preferably 0.05-0.5Mpa; the contact time may be 0.5 to 12 hours, preferably 1 to 5 hours; the weight ratio of the catalyst for preparing the low-carbon olefin from the waste plastics to the waste plastic powder can be 1:0.5 to 50, preferably 1:2-30.
The present invention will be described in detail by examples.
In the following examples and comparative examples:
small angle XRD testing of the samples was performed on a high power, rotary target X-ray diffractometer, D8 ADVANCE, BRUKER AXS, germany, scan range: 0.5-10 deg..
Wide angle XRD testing of the samples was performed on an X' Pert MPD X-ray powder diffractometer, philips company, netherlands, cu ka target, scan range 2θ=5-90 °.
The pore structure parameter analysis of the samples was performed on an ASAP2020-M+C type adsorber available from Micromeritics, inc. The sample was vacuum degassed at 350 ℃ for 4 hours prior to measurement, the specific surface area of the sample was calculated using the BET method, and the pore volume was calculated using the BJH model.
Elemental analysis experiments of the samples were performed on an Eagle III energy dispersive X-ray fluorescence spectrometer manufactured by EDAX, inc. of America.
The drying oven is manufactured by Shanghai-Heng scientific instrument Co., ltd, and the model is DHG-9030A.
The muffle furnace is available from CARBOLITE company under the model CWF1100.
The model NKF-10 zeolite molecular sieves used in the examples and comparative examples were purchased from university of south Kokai catalyst plant; the boehmite powder with model SB was purchased from Beijing Asia Taiao chemical auxiliary agent Co., ltd; pseudo-boehmite powder with the model of P-DF-09-LSi was purchased from Shandong aluminum company, inc.; the macroporous pseudo-boehmite powder with the model PB-0101 is purchased from new material Co., ltd. Of the body Ji Fen of Zibo constant; p123 (EO) 20 PO 70 EO 20 ) Purchased from Sigma-Aldrich Chemistry company; the other reagents used in the examples and comparative examples were purchased from national pharmaceutical chemicals, inc., and the purity of the reagents was analytically pure.
Example 1
(1) Preparation of SBA-15 all-silicon mesoporous molecular sieve
24.0g of nonionic surfactant P123 was added to 600g of 2M aqueous hydrochloric acid and stirred at 35℃for 1 hour; 51.2g of ethyl orthosilicate are added to the solution and stirred for 24 hours at 35 ℃; the mixture was transferred to a hydrothermal kettle and hydrothermally crystallized at 100 ℃ for 24 hours. After the hydrothermal reaction is finished, separating a solid product from a mother solution, washing the solid product to be neutral by deionized water, drying the solid product at 110 ℃ for 6 hours and roasting the solid product at 550 ℃ for 6 hours to obtain the all-silicon SBA-15 mesoporous molecular sieve A.
The specific surface area of the all-silicon SBA-15 mesoporous molecular sieve A is 967m 2 /g; average pore diameter of 7.0nm and pore volume of 1.4cm 3 /g。
(2) Preparation of shaped precursors
86g of the all-silicon SBA-15 mesoporous molecular sieve A prepared in the above steps and 88g of MCM-22 molecular sieve (SiO 2 /Al 2 O 3 Mixing uniformly 37g of pseudo-boehmite powder with the model of P-DF-09-LSi and 7g of cellulose, adding 110g of 5% nitric acid, stirring uniformly, extruding and cutting into a cylinder with the diameter of 2mm and the length of 2 mm; drying at 100℃for 10 hours and finally calcining at 580℃for 6 hours, gives the shaped precursor A.
The content of MCM-22 zeolite molecular sieve was 44 wt.%, the content of SBA-15 all-silica mesoporous molecular sieve A was 43 wt.% and the content of alumina was 13 wt.%, based on the total weight of the shaped precursor A.
(3) Preparation of catalyst for preparing low-carbon olefin from waste plastics
6.6 g of calcium nitrate and 5.0 g of cerium nitrate were dissolved in 1000g of distilled water to obtain a transparent aqueous solution. Mixing 94g of the molding precursor A with the aqueous solution, and stirring and reacting for 6 hours at 50 ℃; solvent water was removed using a rotary evaporator and dried at 80 ℃ for 6 hours to give catalyst intermediate a. 3 g of boric acid was dissolved in 500g of distilled water to obtain an aqueous boric acid solution. The catalyst intermediate A was mixed with an aqueous boric acid solution, stirred at 40℃for 4 hours, and the solid product was dried at 120℃for 15 hours after removing water by using a rotary evaporator, and calcined at 550℃for 6 hours to obtain catalyst A.
The content of the molding precursor was 94% by weight, the content of calcium oxide was 2.2% by weight, the content of cerium oxide was 2.0% by weight, and the content of boron oxide was 1.8% by weight, based on the total weight of the catalyst a.
FIG. 1 is a wide angle XRD spectrum of catalyst A; as can be seen from the spectrum of fig. 1, the x-ray diffraction angles of this sample are mainly: 2θ=7.0 °, 7.1 °, 8.2 °, 10.0 °, 14.2 °, 26.1 °, and 28.1 °. The seven diffraction signals are consistent with the diffraction patterns of the MCM-22 zeolite molecular sieve, which shows that the MCM-22 zeolite molecular sieve in the catalyst A still maintains a regular crystal phase structure, and the basic structure of the MCM-22 zeolite molecular sieve is not damaged in the preparation process of the catalyst. In addition, the wide angle XRD spectrum of catalyst a showed four distinct diffraction signals at 2θ=37.1 °, 45.3 °, 61.0 ° and 66.6 °. These four signals and gamma-Al 2 O 3 The diffraction patterns are identical, which shows that the pseudo-boehmite with the model of P-DF-09-LSi shows typical gamma-Al after being dehydrated after the catalyst A is roasted 2 O 3 A crystalline phase. Diffraction signals corresponding to the modified oxide did not appear in the wide-angle XRD pattern, indicating that the modified oxide was in a uniformly dispersed state on the catalyst.
FIG. 2 is a small angle XRD spectrum of catalyst A; as can be seen from the spectrum of fig. 2, the sample shows one sharp strong diffraction peak and two weaker but clearly discernible diffraction peaks between 2θ=0.5° and 2.0 °. The diffraction signal is a characteristic diffraction peak of the SBA-15 mesoporous molecular sieve. The SBA-15 all-silicon mesoporous molecular sieve has a regular two-dimensional hexagonal phase mesoporous pore structure after being prepared into the catalyst, and the basic structure of the mesoporous molecular sieve is not damaged in the catalyst preparation process.
Catalyst A has a specific surface area of 675m 2 Per gram, pore volume of 0.9cm 3 /g。
(4) Evaluation of reaction performance of preparing low-carbon olefin by directly converting waste plastics
The catalytic cracking reaction performance of the waste plastics of the catalyst was evaluated on a fixed bed reactor. Catalyst A loading 10.0 g, polyethylene waste plastics loading 50.0g, reaction temperature 500 ℃, reaction pressure 0.1MPa, reaction time 2 hours, cooling the product, separating gas and liquid, and preparing gas composition by using Al 2 O 3 -S capillaryAgilent 6890 gas chromatograph analysis of chromatographic column and hydrogen flame detector (FID) adopts temperature programming and uses correction factor to make quantitative analysis; the liquid composition was analyzed with an Agilent 6890 gas chromatograph equipped with a PONA column. The reaction results are shown in Table 1.
Example 2
(1) Preparation of SBA-15 all-silicon mesoporous molecular sieve
30.0g of nonionic surfactant P123 are added to 450g of 1M aqueous hydrochloric acid and stirred at 40℃for 1 hour; 45.0g of methyl orthosilicate is added dropwise to the above solution and stirred at 40℃for 24 hours; the mixture was transferred to a hydrothermal kettle and hydrothermally crystallized at 120 ℃ for 10 hours. After the hydrothermal reaction is finished, separating a solid product from a mother solution, washing the solid product to be neutral by deionized water, drying the solid product at 120 ℃ for 3 hours and roasting the solid product at 450 ℃ for 12 hours to obtain the SBA-15 all-silicon mesoporous molecular sieve B.
The specific surface area of the SBA-15 full-silicon mesoporous molecular sieve B is 920m 2 /g; average pore diameter of 6.7nm and pore volume of 1.3cm 3 /g。
(2) Preparation of shaped precursors
80g of SBA-15 full-silicon mesoporous molecular sieve B prepared in the steps is mixed with 96g of MCM-22 molecular sieve (SiO 2 /Al 2 O 3 Mixing uniformly with 34g of pseudo-boehmite powder with the model PB-0101 and 10g of sesbania powder, adding 110g of 3% nitric acid, stirring uniformly, extruding and cutting into a cylinder with the diameter of 2mm and the length of 2 mm; drying at 120℃for 8 hours and finally calcining at 600℃for 5 hours, to give a shaped precursor B.
The content of MCM-22 zeolite molecular sieve was 48 wt.%, the content of SBA-15 all-silica mesoporous molecular sieve B was 40 wt.%, and the content of alumina was 12 wt.%, based on the total weight of the shaped precursor B.
(3) Preparation of catalyst for preparing low-carbon olefin from waste plastics
6.0 g of magnesium nitrate and 3.8 g of zinc nitrate were dissolved in 800g of distilled water to obtain a transparent aqueous solution. Mixing 96g of the molding precursor B with the aqueous solution, and stirring at 70 ℃ for reaction for 3 hours; solvent water was removed using a rotary evaporator and dried at 120 ℃ for 2 hours to give catalyst intermediate B. 1.6 g of phosphoric acid was dissolved in 400g of distilled water to obtain an aqueous phosphoric acid solution. The catalyst intermediate B was mixed with an aqueous phosphoric acid solution, reacted at 30℃for 5 hours with stirring, the solid product was dried at 150℃for 3 hours after removing water by using a rotary evaporator, and burned at 600℃for 4 hours to obtain catalyst B.
The content of the molding precursor was 96% by weight, the content of magnesium oxide was 1.8% by weight, the content of zinc oxide was 1.2% by weight, and the content of phosphorus-containing oxide was 1.0% by weight, based on the total weight of the catalyst B.
Catalyst B had a specific surface area of 618m 2 Per gram, pore volume of 0.8cm 3 /g。
The reaction performance of the catalyst B was tested according to the evaluation method of the reaction performance of the waste plastics directly converted to light olefins in the step (4) of example 1, and the evaluation results are shown in Table 1.
Example 3
(1) Preparation of SBA-15 all-silicon mesoporous molecular sieve
16.0g of nonionic surfactant P123 are added to 800g of 1.5M aqueous hydrochloric acid and stirred for 1 hour at 40 ℃; 40.0g of water glass (SiO 2 28.26wt percent) of the above solution is added and stirred for 24 hours at 40 ℃; the mixture was transferred to a hydrothermal kettle and hydrothermally crystallized at 80 ℃ for 40 hours. After the hydrothermal reaction is finished, separating a solid product from a mother solution, washing the solid product to be neutral by deionized water, drying the solid product at 70 ℃ for 10 hours and roasting the solid product at 650 ℃ for 3 hours to obtain the SBA-15 all-silicon mesoporous molecular sieve C.
The specific surface area of the SBA-15 all-silicon mesoporous molecular sieve C is 892m 2 /g; average pore diameter of 6.4nm and pore volume of 1.2cm 3 /g。
(2) Preparation of shaped precursors
The SBA-15 full-silicon mesoporous molecular sieve C90 g prepared in the above steps is mixed with 82g MCM-22 molecular sieve (SiO 2 /Al 2 O 3 Mixing uniformly 38g of pseudo-boehmite powder with model SB and 5g of cellulose, adding 106g of 8% dilute nitric acid, stirring uniformly, extruding and cutting into a cylinder with the diameter of 2mm and the length of 2 mm; drying at 80deg.C for 20 hr, and finally at 500deg.CCalcining for 16 hours to obtain a molding precursor C.
The content of MCM-22 zeolite molecular sieve was 41 wt.%, the content of SBA-15 all-silica mesoporous molecular sieve C was 45 wt.%, and the content of alumina was 14 wt.%, based on the total weight of the shaped precursor C.
(3) Preparation of catalyst for preparing low-carbon olefin from waste plastics
5.0 g of strontium nitrate, 4.6 g of lanthanum nitrate and 3.4 g of zinc nitrate were dissolved in 1200g of distilled water to obtain a transparent aqueous solution. 93g of the molding precursor C was mixed with the above aqueous solution and reacted at 40℃for 10 hours with stirring; solvent water was removed using a rotary evaporator and dried at 70 ℃ for 10 hours to give catalyst intermediate C. 2.7 g of boric acid was dissolved in 600g of distilled water to obtain an aqueous boric acid solution. The catalyst intermediate C was mixed with an aqueous boric acid solution, stirred at 60℃for 3 hours, and the solid product was dried at 80℃for 30 hours after removing water by using a rotary evaporator, and calcined at 500℃for 4 hours to give catalyst C.
The content of the molding precursor was 93 wt%, the content of strontium oxide was 2.5 wt%, the content of lanthanum oxide was 1.7 wt%, the content of zinc oxide was 1.2 wt%, and the content of boron oxide was 1.6 wt%, based on the total weight of the catalyst C.
Catalyst C had a specific surface area of 532m 2 Per gram, pore volume of 0.7cm 3 /g。
The reaction performance of the catalyst C was tested according to the evaluation method of the reaction performance of the waste plastics directly converted to light olefins in the step (4) of example 1, and the evaluation results are shown in Table 1.
Example 4
SBA-15 all-silicon mesoporous molecular sieve A was prepared according to the method of step (1) in example 1.
A shaped precursor D was prepared according to the method of step (2) in example 1, except that: the preparation conditions are changed, and the specific process is as follows:
106g of the all-silicon SBA-15 mesoporous molecular sieve A prepared in the above steps and 74g of MCM-22 molecular sieve (SiO 2 /Al 2 O 3 30% by mole), 26g of pseudo-boehmite powder of type P-DF-09-LSi and 8g of cellulose were mixed togetherAfter uniform, 102g of 5% nitric acid is added, stirred uniformly, extruded and cut into a cylinder shape with the diameter of 2mm and the length of 2 mm; drying at 100℃for 10 hours and finally calcining at 580℃for 6 hours, gives the shaped precursor D.
The content of MCM-22 zeolite molecular sieve was 37 wt.%, the content of SBA-15 all-silica mesoporous molecular sieve A was 53 wt.%, and the content of alumina was 10 wt.%, based on the total weight of the molded precursor D.
Catalyst D for producing light olefins from waste plastics was prepared according to the method of step (3) in example 1, except that: the preparation conditions are changed, and the specific process is as follows:
3.3 g of calcium nitrate and 2.5 g of cerium nitrate were dissolved in 1000g of distilled water to obtain a transparent aqueous solution. 97g of the molding precursor D is taken and mixed with the aqueous solution, and stirred and reacted for 6 hours at 50 ℃; solvent water was removed using a rotary evaporator and dried at 80 ℃ for 6 hours to give catalyst intermediate D. 1.5 g of boric acid was dissolved in 500g of distilled water to obtain an aqueous boric acid solution. The catalyst intermediate D was mixed with an aqueous boric acid solution, stirred at 40℃for 4 hours, and the solid product was dried at 120℃for 15 hours after removing water by using a rotary evaporator, and calcined at 550℃for 6 hours to obtain catalyst D.
The content of the molding precursor was 97% by weight, the content of calcium oxide was 1.1% by weight, the content of cerium oxide was 1.0% by weight, and the content of boron oxide was 0.9% by weight, based on the total weight of the catalyst D.
Catalyst D had a specific surface area of 704m 2 Per gram, pore volume of 1.0cm 3 /g。
The reaction performance of catalyst D was tested according to the evaluation method for the reaction performance of the direct conversion of waste plastics to light olefins in step (4) of example 1, and the evaluation results are shown in Table 1.
Example 5
SBA-15 all-silicon mesoporous molecular sieve B was prepared according to the method of step (1) in example 2.
A shaped precursor E was prepared according to the method of step (2) in example 2, except that: the preparation conditions are changed, and the specific process is as follows:
the steps are carried out68g of the prepared SBA-15 all-silicon mesoporous molecular sieve B is mixed with 102g of MCM-22 molecular sieve (SiO 2 /Al 2 O 3 The molar ratio is 30), 43g of pseudo-boehmite powder with the model PB-0101 and 10g of sesbania powder are mixed uniformly, 106g of 3% nitric acid is added, and after uniform stirring, the mixture is extruded and cut into a cylinder shape with the diameter of 2mm and the length of 2 mm; drying at 120℃for 8 hours and finally calcining at 600℃for 5 hours, gives the shaped precursor E.
The content of MCM-22 zeolite molecular sieve was 51 wt.%, the content of SBA-15 all-silica mesoporous molecular sieve B was 34 wt.%, and the content of alumina was 15 wt.%, based on the total weight of the molded precursor E.
Catalyst E for producing light olefins from waste plastics was prepared according to the method of step (3) in example 2, except that: the preparation conditions are changed, and the specific process is as follows:
12.0 g of magnesium nitrate and 7.6 g of zinc nitrate were dissolved in 800g of distilled water to obtain a transparent aqueous solution. 92g of the molding precursor E is taken and mixed with the aqueous solution, and the mixture is stirred and reacted for 3 hours at 70 ℃; solvent water was removed using a rotary evaporator and dried at 120 ℃ for 2 hours to give catalyst intermediate E. 3.2 g of phosphoric acid was dissolved in 400g of distilled water to obtain an aqueous phosphoric acid solution. The catalyst intermediate E was mixed with an aqueous phosphoric acid solution, reacted at 30℃for 5 hours with stirring, the solid product was dried at 150℃for 3 hours after removing water by using a rotary evaporator, and burned at 600℃for 4 hours to obtain catalyst E.
The content of the molding precursor was 92% by weight, the content of magnesium oxide was 3.6% by weight, the content of zinc oxide was 2.4% by weight, and the content of phosphorus-containing oxide was 2.0% by weight, based on the total weight of the catalyst E.
Catalyst E had a specific surface area of 490m 2 Per gram, pore volume of 0.6cm 3 /g。
The reaction performance of the catalyst E was tested according to the evaluation method of the reaction performance of the waste plastics directly converted to light olefins in the step (4) of example 1, and the evaluation results are shown in Table 1.
Example 6
SBA-15 all-silicon mesoporous molecular sieve A was prepared according to the method of step (1) in example 1.
A shaped precursor F was prepared according to the method of step (2) in example 1, except that: the preparation conditions are changed, and the specific process is as follows:
the whole silicon SBA-15 mesoporous molecular sieve A116 g prepared in the above steps is mixed with 68g MCM-22 molecular sieve (SiO 2 /Al 2 O 3 The molar ratio is 30), 11g of pseudo-boehmite powder with the model of P-DF-09-LSi and 8g of cellulose are mixed uniformly, 102g of 5 percent nitric acid is added, and the mixture is extruded and cut into a cylinder shape with the diameter of 2mm and the length of 2mm after uniform stirring; drying at 100℃for 10 hours and finally calcining at 580℃for 6 hours, gives the shaped precursor F.
The content of MCM-22 zeolite molecular sieve was 34 wt.%, the content of SBA-15 all-silica mesoporous molecular sieve A was 58 wt.%, and the content of alumina was 8 wt.%, based on the total weight of the shaped precursor F.
The catalyst F for preparing the low-carbon olefin from the waste plastic is prepared according to the method of the step (3) in the example 1, except that: the preparation conditions are changed, and the specific process is as follows:
2.4 g of calcium nitrate and 1.5 g of cerium nitrate were dissolved in 1000g of distilled water to obtain a transparent aqueous solution. Mixing 98g of the molding precursor F with the aqueous solution, and stirring and reacting for 6 hours at 50 ℃; solvent water was removed using a rotary evaporator and dried at 80 ℃ for 6 hours to give catalyst intermediate F. 1.0 g of boric acid was dissolved in 500g of distilled water to obtain an aqueous boric acid solution. The catalyst intermediate F was mixed with an aqueous boric acid solution, stirred at 40℃for 4 hours, and the solid product was dried at 120℃for 15 hours after removing water by using a rotary evaporator, and calcined at 550℃for 6 hours to give catalyst F.
The content of the molding precursor was 98% by weight, the content of calcium oxide was 0.8% by weight, the content of cerium oxide was 0.6% by weight, and the content of boron oxide was 0.6% by weight, based on the total weight of the catalyst F.
The specific surface area of the catalyst F was 769m 2 Per gram, pore volume of 1.1cm 3 /g。
The reaction performance of the catalyst F was tested according to the evaluation method of the reaction performance of the waste plastics directly converted to light olefins in the step (4) of example 1, and the evaluation results are shown in Table 1.
Example 7
SBA-15 all-silicon mesoporous molecular sieve B was prepared according to the method of step (1) in example 2.
A shaped precursor G was prepared according to the method of step (2) in example 2, except that: the preparation conditions are changed, and the specific process is as follows:
54g of SBA-15 full-silicon mesoporous molecular sieve B prepared in the steps is mixed with 110g of MCM-22 molecular sieve (SiO 2 /Al 2 O 3 The molar ratio is 30), 51g of pseudo-boehmite powder with the model PB-0101 and 10g of sesbania powder are mixed uniformly, 110g of 3% nitric acid is added, and after uniform stirring, the mixture is extruded and cut into a cylinder shape with the diameter of 2mm and the length of 2 mm; drying at 120℃for 8 hours and finally calcining at 600℃for 5 hours, gives the shaped precursor G.
The content of MCM-22 zeolite molecular sieve was 55 wt.%, the content of SBA-15 all-silica mesoporous molecular sieve B was 27 wt.%, and the content of alumina was 18 wt.%, based on the total weight of the shaped precursor G.
Catalyst E for producing light olefins from waste plastics was prepared according to the method of step (3) in example 2, except that: the preparation conditions are changed, and the specific process is as follows:
15.0 g of magnesium nitrate and 9.5 g of zinc nitrate were dissolved in 800g of distilled water to obtain a transparent aqueous solution. Mixing 90G of the molding precursor G with the aqueous solution, and stirring at 70 ℃ for reaction for 3 hours; solvent water was removed using a rotary evaporator and dried at 120 ℃ for 2 hours to give catalyst intermediate G. 4.0 g of phosphoric acid was dissolved in 400g of distilled water to obtain an aqueous phosphoric acid solution. The catalyst intermediate G was mixed with an aqueous phosphoric acid solution, reacted at 30℃for 5 hours with stirring, the solid product was dried at 150℃for 3 hours after removing water by using a rotary evaporator, and burned at 600℃for 4 hours to obtain catalyst G.
The content of the molding precursor was 90% by weight, the content of magnesium oxide was 4.5% by weight, the content of zinc oxide was 3.0% by weight, and the content of phosphorus-containing oxide was 2.5% by weight, based on the total weight of the catalyst G.
Catalyst G has a specific surface area of437m 2 Per gram, pore volume of 0.5cm 3 /g。
The reaction performance of the catalyst E was tested according to the evaluation method of the reaction performance of the waste plastics directly converted to light olefins in the step (4) of example 1, and the evaluation results are shown in Table 1.
Comparative example 1
SBA-15 all-silicon mesoporous molecular sieve A was prepared according to the method of step (1) in example 1.
D1 of the shaped precursor was prepared according to the method of step (2) in example 1, except that: the preparation conditions are changed, and the specific process is as follows:
140g of all-silicon SBA-15 mesoporous molecular sieve A prepared in the steps is mixed with 48g of MCM-22 molecular sieve (SiO 2 /Al 2 O 3 The molar ratio is 30), 9g of pseudo-boehmite powder with the model of P-DF-09-LSi and 7g of cellulose are uniformly mixed, 120g of 5 percent nitric acid is added, and after uniform stirring, the mixture is extruded and cut into a cylinder shape with the diameter of 2mm and the length of 2 mm; drying at 100℃for 10 hours and finally calcining at 580℃for 6 hours, gives the shaped precursor D1.
The content of MCM-22 zeolite molecular sieve was 24% by weight, the content of SBA-15 all-silica mesoporous molecular sieve A was 70% by weight, and the content of alumina was 6% by weight, based on the total weight of the molded precursor D1.
Catalyst D1 for producing light olefins from waste plastics was prepared according to the method of step (3) in example 1, except that: the preparation conditions are changed, and the specific process is as follows:
1.2 g of calcium nitrate and 0.7 g of cerium nitrate were dissolved in 1000g of distilled water to obtain a transparent aqueous solution. Mixing 99g of the molding precursor D1 with the aqueous solution, and stirring and reacting for 6 hours at 50 ℃; solvent water was removed using a rotary evaporator and dried at 80 ℃ for 6 hours to give catalyst intermediate D1. 0.5 g boric acid was dissolved in 500g distilled water to obtain an aqueous boric acid solution. The catalyst intermediate D1 was mixed with an aqueous boric acid solution, stirred at 40℃for 4 hours, and the solid product was dried at 120℃for 15 hours after removing water by using a rotary evaporator and calcined at 550℃for 6 hours to give a catalyst D1.
The content of the molding precursor was 99% by weight, the content of calcium oxide was 0.4% by weight, the content of cerium oxide was 0.3% by weight, and the content of boron oxide was 0.3% by weight, based on the total weight of the catalyst D1.
Catalyst D1 had a specific surface area of 811m 2 Per gram, pore volume of 1.1cm 3 /g。
Catalyst D1 was tested for its reactivity according to the method for evaluating the reactivity of the waste plastics directly converted to light olefins of step (4) of example 1, and the evaluation results are shown in Table 1.
Comparative example 2
SBA-15 all-silicon mesoporous molecular sieve B was prepared according to the method of step (1) in example 2.
A shaped precursor D2 was prepared according to the method of step (2) in example 2, except that: the preparation conditions are changed, and the specific process is as follows:
24g of SBA-15 full-silicon mesoporous molecular sieve B prepared in the steps is mixed with 136g of MCM-22 molecular sieve (SiO 2 /Al 2 O 3 30% molar ratio), 28g of pseudo-boehmite powder with the model PB-0101 and 12g of sesbania powder are mixed uniformly, 115g of 3% nitric acid is added, and after uniform stirring, the mixture is extruded and cut into a cylinder shape with the diameter of 2mm and the length of 2 mm; drying at 120℃for 8 hours and finally calcining at 600℃for 5 hours, gives the shaped precursor D2.
The content of MCM-22 zeolite molecular sieve was 68 wt.%, the content of SBA-15 all-silica mesoporous molecular sieve B was 12 wt.%, and the content of alumina was 20 wt.%, based on the total weight of the molded precursor D2.
Catalyst D2 for producing light olefins from waste plastics was prepared according to the method of step (3) in example 2, except that: the preparation conditions are changed, and the specific process is as follows:
24.0 g of magnesium nitrate and 15.2 g of zinc nitrate were dissolved in 800g of distilled water to obtain a transparent aqueous solution. 84g of the molding precursor D2 is taken and mixed with the aqueous solution, and the mixture is stirred and reacted for 3 hours at 70 ℃; solvent water was removed using a rotary evaporator and dried at 120 ℃ for 2 hours to give catalyst intermediate D2. 6.4 g of phosphoric acid was dissolved in 400g of distilled water to obtain an aqueous phosphoric acid solution. The catalyst intermediate D2 was mixed with an aqueous phosphoric acid solution, reacted at 30℃for 5 hours with stirring, the solid product was dried at 150℃for 3 hours after removing water by using a rotary evaporator, and burned at 600℃for 4 hours to obtain catalyst D2.
The content of the molding precursor was 84% by weight, the content of magnesium oxide was 7.2% by weight, the content of zinc oxide was 4.8% by weight, and the content of phosphorus-containing oxide was 4.0% by weight, based on the total weight of the catalyst D2.
Catalyst D2 had a specific surface area of 384m 2 Per gram, pore volume of 0.4cm 3 /g。
Catalyst D2 was tested for its reactivity according to the method for evaluating the reactivity of the waste plastics directly converted to light olefins of step (4) of example 1, and the evaluation results are shown in Table 1.
Comparative example 3
SBA-15 all-silicon mesoporous molecular sieve A was prepared according to the method of step (1) in example 1.
A shaped precursor D3 was prepared according to the method of step (2) in example 1, except that: the preparation conditions are changed, and the MCM-22 zeolite molecular sieve is not used, and the specific process is as follows:
174g of all-silicon SBA-15 mesoporous molecular sieve A prepared in the steps is uniformly mixed with 37g of pseudo-boehmite powder with the model of P-DF-09-LSi and 7g of cellulose, 110g of 5% nitric acid is added, and the mixture is uniformly stirred, extruded and cut into a cylinder with the diameter of 2mm and the length of 2 mm; drying at 100℃for 10 hours and finally calcining at 580℃for 6 hours, gives the shaped precursor D3.
The content of SBA-15 all-silicon mesoporous molecular sieve A was 87% by weight and the content of alumina was 13% by weight, based on the total weight of the molded precursor D3.
Catalyst D3 for producing light olefins from waste plastics was prepared according to the method of step (3) in example 1. The content of the molding precursor D3 was 94% by weight, the content of calcium oxide was 2.2% by weight, the content of cerium oxide was 2.0% by weight, and the content of boron oxide was 1.8% by weight, based on the total weight of the catalyst D3.
Catalyst D3 had a specific surface area of 857m 2 Per gram, pore volume of 1.2cm 3 /g。
Catalyst D3 was tested for its reactivity according to the method for evaluating the reactivity of the waste plastics directly converted to light olefins of step (4) of example 1, and the evaluation results are shown in Table 1.
Comparative example 4
Catalyst D4 was prepared in the same manner as in example 2, except that: step (1) of example 2 was omitted; a shaped precursor D4 was prepared according to the method of step (2) in example 2, except that: the preparation conditions are changed, and the full-silicon SBA-15 mesoporous molecular sieve is not used, and the specific process is as follows:
176g of MCM-22 molecular sieve (SiO 2 /Al 2 O 3 Mixing uniformly with 34g of pseudo-boehmite powder with the model PB-0101 and 10g of sesbania powder, adding 110g of 3% nitric acid, stirring uniformly, extruding and cutting into a cylinder with the diameter of 2mm and the length of 2 mm; drying at 120℃for 8 hours and finally calcining at 600℃for 5 hours, gives the shaped precursor D4.
The MCM-22 zeolite molecular sieve was 88 wt% and alumina was 12 wt% based on the total weight of the shaped precursor D4.
Catalyst D4 for producing light olefins from waste plastics was prepared according to the method of step (3) in example 2. The content of the molding precursor D4 was 96% by weight, the content of magnesium oxide was 1.8% by weight, the content of zinc oxide was 1.2% by weight, and the content of phosphorus-containing oxide was 1.0% by weight, based on the total weight of the catalyst D4.
Catalyst D4 had a specific surface area of 326m 2 Per gram, pore volume of 0.4cm 3 /g。
Catalyst D4 was tested for its reactivity according to the method for evaluating the reactivity of the waste plastics directly converted to light olefins of step (4) of example 1, and the evaluation results are shown in Table 1.
Comparative example 5
SBA-15 all-silicon mesoporous molecular sieve A was prepared according to the method of step (1) in example 1.
A shaped precursor A was prepared according to the procedure of step (2) in example 1.
Catalyst D5 for producing light olefins from waste plastics was prepared according to the method of step (3) in example 1, except that: the preparation conditions are changed, and the modified oxide is changed into sodium oxide, and the specific process is as follows:
22.2 g of sodium nitrate was dissolved in 1000g of distilled water to obtain a transparent aqueous solution. Mixing 94g of the molding precursor A with the aqueous solution, and stirring and reacting for 6 hours at 50 ℃; the solid product was dried at 120℃for 15 hours after removal of the water using a rotary evaporator and calcined at 550℃for 6 hours to give catalyst D5. The content of the molding precursor A was 94% by weight and the content of sodium oxide was 6% by weight, based on the total weight of the catalyst D5.
Catalyst D5 was tested for its reactivity according to the method for evaluating the reactivity of the waste plastics directly converted to light olefins of step (4) of example 1, and the evaluation results are shown in Table 1.
Comparative example 6
SBA-15 all-silicon mesoporous molecular sieve A was prepared according to the method of step (1) in example 1.
A shaped precursor D6 was prepared according to the method of step (2) in example 1, except that: instead of using pseudo-boehmite powder of the type P-DF-09-LSi as the binder, silica sol of the brand HS-30 (available from Zhejiang Yuda chemical Co., ltd.) was used as the binder. As a result, the content of the MCM-22 zeolite molecular sieve was 44% by weight, the content of the SBA-15 all-silica mesoporous molecular sieve A was 43% by weight, and the content of silica remaining after the binder calcination was 13% by weight, based on the total weight of the molded precursor D6.
The catalyst D6 for low-carbon olefin production from waste plastics was produced in the same manner as in step (3) of example 1, wherein the content of the molding precursor was 94% by weight, the content of calcium oxide was 2.2% by weight, the content of cerium oxide was 2.0% by weight and the content of boron oxide was 1.8% by weight, based on the total weight of the catalyst D6.
Catalyst D6 was tested for its reactivity according to the method for evaluating the reactivity of the waste plastics directly converted to light olefins of step (4) of example 1, and the evaluation results are shown in Table 1.
Comparative example 7
Catalyst D7 was prepared in the same manner as in example 1 except that: the "MCM-22 molecular sieves" in example 1 were replaced with "all-silica Silicalite-1 molecular sieve (available from Tianjin southbound catalyst Co., ltd., specific surface area 318 m) 2 Per gram, pore volume of 0.35cm 3 /g) ", and the specific surface area of the catalyst was 521m 2 Per gram, pore volume of 0.6cm 3 /g。
Catalyst D7 was tested for its reactivity according to the method for evaluating the reactivity of the waste plastics directly converted to light olefins of step (4) of example 1, and the evaluation results are shown in Table 1.
Comparative example 8
Catalyst D8 was prepared in the same manner as in example 1, except that: the "all-silica SBA-15 mesoporous molecular sieve" of example 1 was replaced with "commercially available silica (from Qingdao Seawamori silica gel desiccant plant, specific surface area 329m 2 Per gram, pore volume of 0.6cm 3 /g) ", and the specific surface area of the catalyst was 204m 2 Per gram, pore volume of 0.4cm 3 /g。
Catalyst D8 was tested for its reactivity according to the method for evaluating the reactivity of the waste plastics directly converted to light olefins of step (4) of example 1, and the evaluation results are shown in Table 1.
TABLE 1
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From the results, the catalyst for preparing the low-carbon olefin from the waste plastics can directly catalyze and convert the waste plastics to generate the low-carbon olefin. The conversion rate of the waste plastics is 100 percent, and the yield of the low-carbon olefin is high.
In comparative example 1, the content of SBA-15 full-silica mesoporous molecular sieve was too high, the content of MCM-22 zeolite molecular sieve was too low, and the content of the modifying component was not within the scope of the claims. Because of the small number of acid centers on the catalyst and insufficient activation sites in the reaction process, the raw material conversion rate is low and the low-carbon olefin yield is low.
In comparative example 2, the content of SBA-15 fully-silica mesoporous molecular sieve was too low, the content of MCM-22 zeolite molecular sieve was too high, and the content of the modifying component was not within the scope of the claims. The catalyst has fewer mesoporous channels, and the low-carbon olefin yield is lower due to the fact that the diffusion of reactant and product molecules is blocked in the reaction process.
In comparative example 3, the catalyst contained no MCM-22 zeolite molecular sieve and only SBA-15 all-silica mesoporous molecular sieve. Because the catalyst contains almost no acid center, the active sites are seriously lacking in the reaction process, so that the raw material conversion rate is very low, and the low-carbon olefin yield is low.
In comparative example 4, the catalyst contained no SBA-15 fully siliceous mesoporous molecular sieve and only MCM-22 zeolite molecular sieve. Because the catalyst contains almost no mesoporous pore canal, the diffusion of reactant and product molecules is seriously hindered in the reaction process, so that the yield of the low-carbon olefin is lower.
In comparative example 5, sodium oxide was used instead of the modified oxide specifically defined in the present invention, and the lower yield of the lower olefin was caused by the lower modifying effect of sodium oxide of the same weight.
In comparative example 6, pseudo-boehmite powder having a model of P-DF-09-LSi was not used as a binder, but silica sol having a trademark of HS-30 (available from Zhejiang Yuda chemical Co., ltd.) was used as a binder, and the residual component of the binder after firing was silica. Because of the poor bonding effect when the silica sol is used as a binder in the invention, the formed precursor has irregular shape and poor strength, and the mixing of the components is not uniform. Therefore, the catalyst is poor in effect in the reaction process, resulting in lower yield of low-carbon olefin.
In comparative example 7, "MCM-22 molecular sieve" was replaced with "all-silica silicalite-1 molecular sieve". All-silica silicalite-1 molecular sieves are microporous materials, but have extremely weak surface acidity and little catalytic activity. Therefore, the prepared catalyst D7 has almost no acidic center on the surface, and the waste plastics lack of activation sites in the catalytic cracking reaction process, so that the raw materials only generate thermal cracking, and the conversion rate and the low-carbon olefin yield are lower.
In comparative example 8, "all-silicon SBA-15 mesoporous molecular sieve A" was replaced with "commercially available silica". Although the pore canal of the commercially available silicon dioxide also belongs to the mesoporous category, the silica belongs to an amorphous crystal phase structure, the pore canal is irregular in size, and compared with the all-silicon SBA-15 mesoporous molecular sieve, the silica has poor diffusion promotion effect, so that the yield of the low-carbon olefin is lower.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (15)
1. The catalyst for preparing the low-carbon olefin from the waste plastics is characterized by comprising a molding precursor and a modified oxide loaded on the molding precursor, wherein the molding precursor comprises an MCM-22 zeolite molecular sieve, an SBA-15 full-silicon mesoporous molecular sieve and aluminum oxide, the content of the molding precursor is 90-98 wt% and the content of the modified oxide is 2-10 wt% based on the total weight of the catalyst for preparing the low-carbon olefin from the waste plastics.
2. The catalyst for producing light olefins from waste plastics according to claim 1, wherein the molding precursor is contained in an amount of 92 to 97% by weight and the modified oxide is contained in an amount of 3 to 8% by weight, based on the total weight of the catalyst for producing light olefins from waste plastics;
preferably, the molding precursor is contained in an amount of 93 to 96 wt% and the modified oxide is contained in an amount of 4 to 7 wt% based on the total weight of the catalyst for producing light olefins from waste plastics.
3. The catalyst for producing low-carbon olefin from waste plastics according to claim 1 or 2, wherein the content of the MCM-22 zeolite molecular sieve is 34-55 wt%, the content of the SBA-15 all-silicon mesoporous molecular sieve is 27-58 wt%, and the content of the alumina is 8-18 wt%, based on the total weight of the molding precursor;
preferably, the content of the MCM-22 zeolite molecular sieve is 37-51 wt%, the content of the SBA-15 all-silicon mesoporous molecular sieve is 34-53 wt% and the content of the alumina is 10-15 wt% based on the total weight of the molding precursor;
more preferably, the MCM-22 zeolite molecular sieve is present in an amount of 41 to 48 wt%, the SBA-15 all-silica mesoporous molecular sieve is present in an amount of 40 to 45 wt% and the alumina is present in an amount of 12 to 14 wt%, based on the total weight of the shaped precursor.
4. The catalyst for preparing light olefins from waste plastics according to claim 1 or 3, wherein the average pore diameter of the SBA-15 all-silicon mesoporous molecular sieve is 5-8nm, and the specific surface area is 650-1100m 2 Per gram, pore volume of 1.2-1.6cm 3 /g；
And/or the specific surface area of the MCM-22 zeolite molecular sieve is 400-600m 2 Per gram, pore volume of 0.4-0.7cm 3 /g；
And/or the specific surface area of the catalyst for preparing the low-carbon olefin from the waste plastics is 400-800m 2 Per gram, pore volume of 0.5-1.1cm 3 /g; preferably, the specific surface area of the catalyst is 532-675m 2 Per gram, pore volume of 0.7-0.9cm 3 /g。
5. The catalyst for producing light olefins from waste plastics according to claim 1 or 2, wherein the modified oxide is one or more selected from alkaline earth metal oxide, transition metal oxide, rare earth metal oxide and nonmetal oxide;
preferably, the modified oxide is selected from one or more of magnesium oxide, calcium oxide, strontium oxide, barium oxide, zinc oxide, cerium oxide, lanthanum oxide, zirconium dioxide, phosphorus-containing oxide and boron oxide.
6. The catalyst for producing light olefins from waste plastics according to any one of claims 1 to 5, wherein the method for preparing the molding precursor comprises:
in the presence of an acidic aqueous solution, mixing an MCM-22 zeolite molecular sieve, an all-silicon SBA-15 mesoporous molecular sieve, an alumina precursor and an extrusion aid, performing extrusion molding, and performing drying and roasting treatment to obtain a molding precursor.
7. The catalyst for producing light olefins from waste plastics according to claim 6 in which the acidic aqueous solution is one or more selected from dilute nitric acid, dilute hydrochloric acid, dilute phosphoric acid and dilute sulfuric acid, preferably dilute nitric acid;
and/or the concentration of the acidic aqueous solution may be 1-30%, preferably 2-15%;
and/or the alumina precursor is selected from one or more of pseudo-boehmite, aluminum hydroxide gel, alumina sol, gibbsite and boehmite;
and/or the extrusion aid is selected from one or more of cellulose, sesbania powder, polyacrylamide, polyvinyl alcohol, glycerol and polyethylene glycol, preferably cellulose or sesbania powder;
and/or the weight ratio of the MCM-22 molecular sieve, the all-silicon SBA-15 mesoporous molecular sieve, the alumina precursor, the extrusion aid and the acidic aqueous solution is 1: (0.4-2): (0.2-0.6): (0.02-0.16): (0.8-1.6), preferably 1: (0.6-1.5): (0.3-0.5): (0.04-0.12): (1.0-1.4);
and/or, the roasting conditions include: the temperature is 450-650 ℃ and the time is 2-30h.
8. The preparation method of the catalyst for preparing the low-carbon olefin from the waste plastics is characterized by comprising the following steps:
(1) Mixing the molding precursor with an aqueous solution of metal salt, performing a first contact reaction, and performing water removal and first drying treatment to obtain a catalyst intermediate; the molding precursor comprises an MCM-22 zeolite molecular sieve, an SBA-15 all-silicon mesoporous molecular sieve and alumina;
(2) And mixing the catalyst intermediate with an acidic aqueous solution, performing a second contact reaction, and performing water removal, second drying and roasting treatment to obtain the catalyst for preparing the low-carbon olefin from the waste plastics.
9. The production process according to claim 8, wherein in the step (1), the metal salt is selected from the group consisting of inorganic salts containing alkaline earth metals, transition metals and rare earth metals; preferably, the modified oxide precursor is selected from the group consisting of inorganic salts containing magnesium, calcium, strontium, barium, zinc, cerium, lanthanum and zirconium;
and/or in step (1), the concentration of the aqueous solution of the metal salt is 1-20%, preferably 2-10%;
and/or, in step (1), the conditions of the first contact reaction include: the temperature is 20-90 ℃ and the time is 0.5-20h;
and/or, in the step (1), the weight ratio of the molding precursor to the aqueous solution of the metal salt is 1: (2-30), preferably 1: (5-20).
10. The production process according to claim 8, wherein in the step (2), the acidic aqueous solution is selected from one or more of phosphoric acid or boric acid;
And/or in step (2), the concentration of the acidic aqueous solution is 0.5-10%, preferably 1-5%;
and/or, in step (2), the weight ratio of the catalyst intermediate to the acidic aqueous solution is 1: (1-20), preferably 1: (3-15);
and/or, in step (2), the conditions of the second contact reaction include: the temperature is 20-90 ℃ and the time is 0.5-10h;
and/or, in step (2), the roasting conditions include: the temperature is 450-650 ℃, preferably 500-600 ℃; the time is 2-20h, preferably 3-10h.
11. The production process according to claim 8, wherein the MCM-22 zeolite molecular sieve is contained in an amount of 34 to 55 wt%, the SBA-15 all-silica mesoporous molecular sieve is contained in an amount of 27 to 58 wt%, and the alumina is contained in an amount of 8 to 18 wt%, based on the total weight of the molding precursor;
preferably, the content of the MCM-22 zeolite molecular sieve is 37-51 wt%, the content of the SBA-15 all-silicon mesoporous molecular sieve is 34-53 wt% and the content of the alumina is 10-15 wt% based on the total weight of the molding precursor;
more preferably, the MCM-22 zeolite molecular sieve is present in an amount of 41 to 48 wt%, the SBA-15 all-silica mesoporous molecular sieve is present in an amount of 40 to 45 wt% and the alumina is present in an amount of 12 to 14 wt%, based on the total weight of the shaped precursor.
12. The preparation method of claim 8 or 11, wherein the average pore diameter of the SBA-15 all-silicon mesoporous molecular sieve is 5-8nm, and the specific surface area is 650-1100m 2 Per gram, pore volume of 1.2-1.6cm 3 /g；
And/or the specific surface area of the MCM-22 zeolite molecular sieve is 400-600m 2 Per gram, pore volume of 0.4-0.7cm 3 /g。
13. A catalyst for producing light olefins from waste plastics produced by the production method according to any one of claims 8 to 12.
14. Use of the catalyst for preparing low-carbon olefin from waste plastics according to any one of claims 1-7 and 13 in the reaction for preparing low-carbon olefin by directly converting waste plastics.
15. The application of claim 14, wherein the application comprises: the plastic powder is contacted with the catalyst for preparing the low-carbon olefin from the waste plastic for reaction;
and/or, the contacting conditions include: the temperature is 420-580 ℃, the pressure is 0.01-1MPa, and the contact time is 0.5-12h;
and/or the weight ratio of the catalyst for preparing the low-carbon olefin from the waste plastics to the dosage of the waste plastic powder is 1: (0.5-50).
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