JPH0516886B2 - - Google Patents
Info
- Publication number
- JPH0516886B2 JPH0516886B2 JP2204102A JP20410290A JPH0516886B2 JP H0516886 B2 JPH0516886 B2 JP H0516886B2 JP 2204102 A JP2204102 A JP 2204102A JP 20410290 A JP20410290 A JP 20410290A JP H0516886 B2 JPH0516886 B2 JP H0516886B2
- Authority
- JP
- Japan
- Prior art keywords
- exhaust gas
- catalyst
- nox
- hydrocarbons
- reaction
- 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.)
- Expired - Lifetime
Links
- 239000007789 gas Substances 0.000 claims description 68
- 239000003054 catalyst Substances 0.000 claims description 61
- 238000000034 method Methods 0.000 claims description 40
- 229930195733 hydrocarbon Natural products 0.000 claims description 38
- 150000002430 hydrocarbons Chemical class 0.000 claims description 38
- 239000010457 zeolite Substances 0.000 claims description 30
- 229910044991 metal oxide Inorganic materials 0.000 claims description 20
- 150000004706 metal oxides Chemical class 0.000 claims description 20
- 230000003647 oxidation Effects 0.000 claims description 20
- 238000007254 oxidation reaction Methods 0.000 claims description 20
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 18
- 239000001301 oxygen Substances 0.000 claims description 18
- 229910052760 oxygen Inorganic materials 0.000 claims description 18
- 230000001590 oxidative effect Effects 0.000 claims description 10
- 150000001875 compounds Chemical class 0.000 claims description 9
- 230000002378 acidificating effect Effects 0.000 claims description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 229910052783 alkali metal Inorganic materials 0.000 claims description 6
- 150000001340 alkali metals Chemical class 0.000 claims description 6
- QAOWNCQODCNURD-UHFFFAOYSA-L sulfate group Chemical group S(=O)(=O)([O-])[O-] QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 6
- 238000000746 purification Methods 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 38
- 229910002089 NOx Inorganic materials 0.000 description 32
- 238000006243 chemical reaction Methods 0.000 description 29
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 27
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 25
- 229910021536 Zeolite Inorganic materials 0.000 description 24
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 22
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 15
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 14
- 239000004215 Carbon black (E152) Substances 0.000 description 12
- 238000006722 reduction reaction Methods 0.000 description 12
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 10
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 10
- 229910002091 carbon monoxide Inorganic materials 0.000 description 10
- 230000000694 effects Effects 0.000 description 10
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 9
- 238000000354 decomposition reaction Methods 0.000 description 9
- 239000001294 propane Substances 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 8
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 7
- 239000000377 silicon dioxide Substances 0.000 description 7
- -1 sulfate radical Chemical class 0.000 description 7
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 6
- 229910004298 SiO 2 Inorganic materials 0.000 description 5
- 239000001569 carbon dioxide Substances 0.000 description 5
- 229910002092 carbon dioxide Inorganic materials 0.000 description 5
- 238000002485 combustion reaction Methods 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 230000002829 reductive effect Effects 0.000 description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 4
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 150000002739 metals Chemical class 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 238000011144 upstream manufacturing Methods 0.000 description 4
- 239000004115 Sodium Silicate Substances 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 3
- 239000001307 helium Substances 0.000 description 3
- 229910052734 helium Inorganic materials 0.000 description 3
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 3
- 229910052697 platinum Inorganic materials 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 3
- 229910052911 sodium silicate Inorganic materials 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- PAWQVTBBRAZDMG-UHFFFAOYSA-N 2-(3-bromo-2-fluorophenyl)acetic acid Chemical compound OC(=O)CC1=CC=CC(Br)=C1F PAWQVTBBRAZDMG-UHFFFAOYSA-N 0.000 description 2
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 229910010413 TiO 2 Inorganic materials 0.000 description 2
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 description 2
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 2
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 2
- 235000011130 ammonium sulphate Nutrition 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 239000010953 base metal Substances 0.000 description 2
- 238000001354 calcination Methods 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 235000014413 iron hydroxide Nutrition 0.000 description 2
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 description 2
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000000395 magnesium oxide Substances 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 2
- 229910052763 palladium Inorganic materials 0.000 description 2
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 2
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical class S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 2
- 229910052815 sulfur oxide Inorganic materials 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 229910052726 zirconium Inorganic materials 0.000 description 2
- 229910001928 zirconium oxide Inorganic materials 0.000 description 2
- IVORCBKUUYGUOL-UHFFFAOYSA-N 1-ethynyl-2,4-dimethoxybenzene Chemical compound COC1=CC=C(C#C)C(OC)=C1 IVORCBKUUYGUOL-UHFFFAOYSA-N 0.000 description 1
- MGWGWNFMUOTEHG-UHFFFAOYSA-N 4-(3,5-dimethylphenyl)-1,3-thiazol-2-amine Chemical compound CC1=CC(C)=CC(C=2N=C(N)SC=2)=C1 MGWGWNFMUOTEHG-UHFFFAOYSA-N 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- 229910052684 Cerium Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 1
- 229910000608 Fe(NO3)3.9H2O Inorganic materials 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- QIGYHBZPYMHYBE-UHFFFAOYSA-N [Co](=O)(=O)=O.[La] Chemical compound [Co](=O)(=O)=O.[La] QIGYHBZPYMHYBE-UHFFFAOYSA-N 0.000 description 1
- KFVPJMZRRXCXAO-UHFFFAOYSA-N [He].[O] Chemical compound [He].[O] KFVPJMZRRXCXAO-UHFFFAOYSA-N 0.000 description 1
- BRKPBIYPTNKPQY-UHFFFAOYSA-M [O-2].[O-2].[OH-].[Fe+2].[La+3] Chemical compound [O-2].[O-2].[OH-].[Fe+2].[La+3] BRKPBIYPTNKPQY-UHFFFAOYSA-M 0.000 description 1
- RXJQIRDQFAJTOM-UHFFFAOYSA-J [O-]O[O-].[Sr+2].[Co+2].[O-]O[O-] Chemical compound [O-]O[O-].[Sr+2].[Co+2].[O-]O[O-] RXJQIRDQFAJTOM-UHFFFAOYSA-J 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 150000001336 alkenes Chemical class 0.000 description 1
- ANBBXQWFNXMHLD-UHFFFAOYSA-N aluminum;sodium;oxygen(2-) Chemical compound [O-2].[O-2].[Na+].[Al+3] ANBBXQWFNXMHLD-UHFFFAOYSA-N 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 235000019270 ammonium chloride Nutrition 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 238000010531 catalytic reduction reaction 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
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 239000002283 diesel fuel Substances 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 150000002170 ethers Chemical class 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 239000013067 intermediate product Substances 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 1
- 150000002576 ketones Chemical class 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 150000007530 organic bases Chemical class 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 description 1
- DCKVFVYPWDKYDN-UHFFFAOYSA-L oxygen(2-);titanium(4+);sulfate Chemical compound [O-2].[Ti+4].[O-]S([O-])(=O)=O DCKVFVYPWDKYDN-UHFFFAOYSA-L 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 229940018489 pronto Drugs 0.000 description 1
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 1
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000012495 reaction gas Substances 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910001388 sodium aluminate Inorganic materials 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 125000000383 tetramethylene group Chemical group [H]C([H])([*:1])C([H])([H])C([H])([H])C([H])([H])[*:2] 0.000 description 1
- BGQMOFGZRJUORO-UHFFFAOYSA-M tetrapropylammonium bromide Chemical compound [Br-].CCC[N+](CCC)(CCC)CCC BGQMOFGZRJUORO-UHFFFAOYSA-M 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 229910000348 titanium sulfate Inorganic materials 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
Landscapes
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Catalysts (AREA)
Description
〔産業上の利用分野〕
本発明は、過剰の酸素が存在する全体として酸
化条件下において、排ガス中の窒素酸化物を、少
量添加して炭化水素又は排ガス中に残存する炭化
水素の存在下で、特定の触媒と接触させ、排ガス
中の窒素酸化物を除去する排ガス浄化方法に関す
る。
〔従来の技術〕
各種の排ガス中の窒素酸化物(以下、「NOx」)
は、健康に有害であり、かつ光化学スモツグや酸
性雨の発生原因ともなり得るため、その効果的処
理手段の開発が望まれている。
従来、このNOxの除去方法として、触媒を用
いて排ガス中のNOxを低減する方法が既にいく
つか実用化されている。
例えば、(イ)ガソリン自動車における三元触媒法
や、(ロ)ボイラー等の大型設備排出源からの排ガス
についてアンモニアを用いる選択的接触還元法が
挙げられる。
また、その他の提案されている方法としては、
(ハ)炭化水素を用いる排ガス中のNOxの除去方法
として、各種金属を含むゼオライトを炭化水素の
存在下でNOxを含むガスと接触させる方法(特
開昭63−283727号公報等)があり、触媒としては
ゼオライトに各種の金属を添加したものが提案さ
れている。
更に、本発明者らにより、(ニ)炭化水素を用いる
排ガス中のNOxの除去方法として、炭化水素の
存在下で、特定のゼオライトや酸性を有する金属
酸化物とNOxを含む排ガスとを接触させる方法
が提案されている(特願平2−139340号公報)。
〔発明が解決しようとする課題〕
上記(イ)の方法は、自動車の燃焼排ガス中に含ま
れる炭化水素成分と一酸化炭素を触媒によつて水
と二酸化炭素とし、同時にNOxを還元して窒素
とするものであるが、NOxに含まれる酸素量と、
炭化水素成分と一酸化炭素が酸化されるのに必要
とする酸素量とが化学的に等量となるように燃焼
を調整する必要があり、デイーゼルエンジンのよ
うに過剰の酸素が存在する系では、原理的に適用
は不可能である。
また、(ロ)の方法では、有毒かつ可燃性の高圧ガ
スであるアンモニアを用いるため保安上巨大な設
備が必要であり、排ガス発生源が移動する場合に
適用することは技術的に極めて困難である。
一方、(ハ)の方法は、ガソリン自動車を主な対象
としており、デイーゼル機関の排ガス条件下では
適用が困難であると共に、活性も不充分である。
すなわち、触媒の成分として各種金属類を含むた
め、デイーゼル機関から排出される硫黄酸化物に
より被毒されるばかりでなく、添加した金属が凝
集する等して活性の低下も起こるため、デイーゼ
ル機関からの排ガス中のNOxを除去するには適
さず、実用化には至つていない。
また、(ニ)の方法は、炭化水素の存在下で従来よ
りも効率的にNOxを分解除去できるが、用いる
触媒、反応温度等の反応条件により、還元剤とし
て添加する炭化水素や酸化の中間生成物である一
酸化炭素が流出する場合がある。
本発明は、以上の(イ)〜(ニ)に存在する各種の問題
について検討した結果なされたものであつて、酸
化雰囲気において、デイーゼル機関排ガスをはじ
め、種々の設備からの排ガス中のNOxを効率良
く除去すると共に、他の有害成分を排出しない排
ガス浄化方法を提案することを目的とする。
〔課題を解決するための手段及び作用〕
本発明者等は、上記の従来技術に存在する問題
を解決するために、鋭意研究を重ねた結果、特定
の触媒を特定の組合せで用いることにより、硫黄
酸化物の含まれている排ガスにおいても活性の低
下を引き起こすことなく、また一酸化炭素等の有
害物質を排出することなく、従来より高い割合で
NOxを除去することができることを見出し、本
発明を完成するに至つた。
すなわち、本発明の排ガス浄化方法は、上記の
目的に達成するために、過剰の酸素が存在する酸
化雰囲気中、炭化水素の存在下において、プロト
ン型ゼオライト、アルカリ金属型ゼオライト又は
酸性を有する金属酸化物から選ばれる1種以上の
触媒とNOxを含む排ガスとを接触させ、次いで
該排ガスを酸化触媒に接触させることを特徴とす
る。
また、本発明の排ガス浄化方法は、上記の酸性
を有する金属酸化物として、硫酸根を有する化合
物により処理した金属酸化物を使用することをも
特徴とする。
以下、本発明方法の詳細を作用と共に説明す
る。
本発明方法では、被処理排ガスを還元触媒と酸
化触媒に段階的に接触させる。
このとき、上段側(すなわち、排気上流側)に
て使用することのできる触媒は、プロトン型ゼオ
ライト、アルカリ金属型ゼオライト、又はアルミ
ナ(酸化アルミニウム)、シリカアルミナのよう
な酸性を有する金属酸化物から選ばれる1種以上
の還元触媒である。
本発明方法における上記のゼオライトは、具体
的には、ペンタシル型ゼオライト、モルデナイ
ト、Y型ゼオライト、X型ゼオライト、L型ゼオ
ライト、シリカライト等の各種のゼオライトが使
用できる。
これらゼオライトのケイバン比(SiO2対Al2O3
の式量比)は、特に制限されるものではないが、
熱や水蒸気に対する安定性等から比較的高いもの
が好ましく、より好ましくは約5〜200、更に好
ましくは約10〜100である。
これらゼオライトは、公知の方法で製造するこ
とができ、シリカ、シリカゾル、ケイ酸ナトリウ
ム等のシリカ源、アルミナゲル、アルミナゾル、
アルミン酸ナトリウム等のアルミナ源、水酸化ナ
トリウム、ケイ酸ナトリウム等のアルカリ源、
水、そして必要に応じてアミン等の有機塩基を含
む原料混合物を水熱合成し、生成物を分離後、水
洗、乾燥してアルカリ金属型ゼオライトとするこ
とができる。
完全にNa型とするためには、イオン交換する
ことにより可能となる。
ここで、アルカリ金属型ゼオライトを、塩化ア
ンモニウムあるいは硝酸アンモニウム水溶液等で
処理してアンモニウム型のゼオライトとし、しか
る後、約400〜700℃の温度範囲で焼成してプロン
ト型ゼオライトとすることができる。
プロトン型ゼオライトを用いることにより、よ
り一層効率的にNOxを分解除去することが可能
となる。
更に、本発明方法においては、酸性を有する金
属酸化物をも使用することができ、例えば、アル
ミナ(Al2O3)、酸化チタン(TiO2)、酸化ジルコ
ニウム(ZrO2)等の金属酸化物、シリカアルミ
ナ(SiO2・Al2O3)、シリカマグネシア(SiO2・
MgO)、シリカジルコニア(SiO2・ZrO2)、アル
ミナチタン(Al2O3・TiO2)等のような複合酸化
物が挙げられる。
また、金属酸化物3成分以上からなるものでも
固体酸性を示すものであれば有効に使用でき、酸
性が強く酸量が多いものが特に好ましい。
その他の金属酸化物の例として、硫酸根を有す
る化合物で処理して調製した金属酸化物を使用す
ることができ、未処理の金属酸化物よりも一層効
率的にNOxを分解することができる。
硫酸根を有する化合物の具体例として、硫酸、
硫酸アンモニウム等を挙げることができ、その他
処理後の乾燥焼成により金属酸化物上で硫酸根が
生成する化合物であれば用いることができる。
硫酸根を有する化合物、例えば、硫酸による処
理を行う金属酸化物触媒の調製は、アルミナ
(Al2O3)、酸化チタン(TiO2)等のような金属酸
化物を、室温で特定の濃度の硫酸と接触させ、乾
燥後、特定の温度で空気焼成することにより得ら
れるが、比晶質の酸化物あるいは対応する水酸化
物を硫酸で同様に処理することによつて、より一
層高い活性の触媒が得られる。
処理に使用する硫酸の濃度は、酸化物の種類に
より異なるが、通常、約0.01〜10mol/l,好ま
しくは約0.1〜5mol/lであり、該濃度の硫酸を
触媒重量当たり約5〜20倍量使用し、金属酸化物
と接触させる。
ここで、硫酸の濃度が約0.01mol/l未満で
は、硫酸との接触によるNOx分解活性への効果
は余り期待できず、また約10mol/lを超える
と、金属硫酸塩の生成あるいは触媒構造の破壊等
が起こる虞れがあり余り好ましくない。
また、硫酸アンモニウムを硫酸根を有する化合
物として処理に用いる場合も、上記と同様の方法
で処理することができる。
空気焼成温度も、酸化物の種類により最適温度
は異なるが、通常、約300〜850℃、好ましくは約
400〜700℃である。
空気焼成温度が約300℃未満では、処理に用い
た硫酸等の化合物が除去できず、触媒活性点が形
成されない虞があり、850℃を超えると、触媒表
面積の減少あるいは触媒活性点の破壊が生じる可
能性がある。
一方、本発明方法において、下段側(すなわ
ち、排気下流側)に使用することができる酸化触
媒としては、活性アルミナ、シリカ、ジルコニア
等の多孔質担体に、例えば、白金、パラジウム、
ロジウム、ルテニウム、イリジウム等の貴金属、
ランタン、セリウム、銅、鉄等の卑金属、三酸化
コバルトランタン、三酸化鉄ランタン、三酸化コ
バルトストロンチウム等のペロブスカイト型結晶
構造物等の触媒成分を単独又は組合せて担持した
ものが挙げられる。
この場合の触媒成分の担持量は、貴金属では担
体に対し約0.01〜2wt%程度であり、また卑金属
では約5〜70wt%程度である。
担持量が夫々少ない場合は、酸化触媒としての
効果が余り期待できす、また夫々の適量を超えて
担持してもそれに見合うだけの効果の向上は得ら
れない。
上記の還元触媒と酸化触媒との使用比率や、酸
化触媒に担持する触媒成分量等は、要求性能に応
じて適宜選択可能であり、特に、酸化除去する物
質が一酸化炭素のような炭化水素の中間酸化物で
ある場合には、還元触媒と酸化触媒とを混合して
使用することも可能であるが、一般には、還元触
媒を排気上流側に、酸化触媒を排気下流側に配置
する。
これらの触媒を用いて排ガスを浄化する具体例
としては、還元触媒を配置した反応器を排ガス導
入部(前段)に、酸化触媒を配置した反応器を排
ガス排出部(後段)に配置して用いる方法がある
また、1つの反応器に夫々の触媒を要求性能に
応じた比率で配置して用いることも可能である。
還元触媒(A)と酸化触媒(B)の比率は、一般には
(A)/(B)で表して約0.5/9.5〜9.5/0.5の範囲で用
いられる。
以上の触媒は、粉状、粒体状、ペレツト状、ハ
ニカム状等、その形状、構造は問わない。
また、触媒の成型等の目的で使用するシリカ等
の非酸性の酸化物、シリカゾル、あるいはカーボ
ンワツクス、油脂等の成型剤を混合することも可
能である。
本発明方法の処理対象となるNOx含有ガスと
しては、デイーゼル自動車や定置式デイーゼル機
関等のデイーゼルエンジン排ガス、ガソリン自動
車等のガソリンエンジン排ガスをはじめ、硝酸製
造工場、各種の燃焼設備等の排ガスを挙げること
ができる。
これら排ガス中のNOxの除去は、上記触媒を
用い、上記触媒に、酸化雰囲気中、炭化水素の存
在下で、排ガスを接触させることにより行う。
ここで、酸化雰囲気とは、排ガス中に含まれる
一酸化炭素、水素及び炭化水素と、本発明方法お
いて必要に応じて添加する炭化水素の還元性物質
を完全に酸化して水と二酸化炭素に変換するのに
必要な酸素量よりも過剰な酸素が含まれている雰
囲気をいい、例えば、自動車等の内燃機関から排
出される排ガスの場合には空気比が大きい状態
(リーン領域)の雰囲気であり、通常、過剰酸素
率は約20〜200%程度である。
この酸化雰囲気中において、上記の排気上流側
に配置された触媒は、炭化水素と酸素との反応よ
りも、炭化水素とNOxとの反応を優先的に促進
させて、NOxを分解する。
存在させる炭化水素としては、排ガス中に残留
する炭化水素でもよいが、上記反応を促進させる
のに必要な量よりも不足している場合には、外部
より炭化水素を添加する必要がある。
炭化水素量は、特に制限されないが、NOxの
還元分解に必要な量よりも過剰な方がより還元反
応が進むので、過剰に添加するのが好ましく、通
常、炭化水素の使用量はNOxの還元分解に必要
な理論量の約20〜2000%、好ましくは約30〜1500
%過剰に存在させる。
ここで、必要な炭化水素の理論量とは、反応系
内に酸素が存在するので、本発明においては、二
酸化窒素(NO2)に還元分解するのに必要な炭
化水素と定義するものであり、例えば、炭化水素
としてプロパンを用いて1000ppmの一酸化窒素
(NO)を酸素存在下で還元分解する際のプロパ
ンの理論量は200ppmとなる。
一般には、排ガス中のNOx量にもよるが、存
在させる炭化水素の量は、メタン換算で約50〜
10000ppm程度である。
本発明に用いる炭化水素としては、気体状、液
体状を含め特に限定されず、反応温度で気化する
ものであれば使用可能である。
気体状のものとしては、メタン、エタン、プロ
パン、エチレン、プロピレン、ブチレン等の炭化
水素を具体例として挙げることができ、液体状の
ものとしては、ガソリン、軽油他の石油系炭化水
素、アルコール類、エーテル類、ケトン類等の含
酸素化合物を挙げることができる。
反応は、上記ゼオライト又は金属酸化物を配置
した反応器を排気上流側に用意して、酸化雰囲気
中で炭化水素を存在させて、NOx含有排ガスを
通過させることにより行う。
以上の工程により、排ガス中のNOxを還元分
解することができるが、更に排気下流側に酸化触
媒を配置した反応器を用意し、連続して排ガスを
通過させることにより、NOx除去と炭化水素及
び一酸化炭素等の有害成分を酸化することにより
除去することができる。
このときの反応温度は、触媒及び炭化水素の種
類により最適温度が異なるが、排ガスの温度に近
い温度が排ガス加熱設備等を必要としないので好
ましく、約200〜800℃、特に約300〜600℃の範囲
での使用が有効である。
ここで、オレフイン類を添加炭化水素として用
いた場合は、パラフイン類を用いた場合よりもや
や低い温度が好ましい。
反応圧力は、特に制限されず、通常の排気圧力
で反応が進行し、また排ガスを触媒層へ導入する
空間速度(SV)は、反応温度等の他の反応条件
や要求されるNOx及び有害成分の除去率により
異なり、特に制限はないが、約500〜
100000Hr-1、好ましくは約1000〜70000Hr-1の範
囲である。
なお、本発明方法において、内燃機関からの排
ガスを処理する場合は、上記触媒は、排気マニホ
ールドの下流に配置するのが好ましい。
〔実施例〕
次に、本発明方法の実施例を挙げるが、本発明
方法は、これらの実施例によつて制限されるもの
ではない。
実施例 1
(ペンタシル型ゼオライトの調製)
水1200gにケイ酸ナトリウム957gを溶解させ
た水溶液中に、水1600gに硫酸アルミニウム41
g、濃硫酸80g、塩化ナトリウム360gを溶解さ
せた水溶液を、30分で徐々に攪拌しながら加え混
合した。
更に、臭化テトラプロピルアンモニウム120g
を加え、PH10に調整した。
この混合液をオートクレーブに仕込み、165℃
で16時間攪拌したところ、結晶化した。
生成物を分離後、水洗、乾燥して基剤となる
SiO2/Al2O3=62.7のペンタシル型であるZSM−
5ゼオライトを得た。
(プロトン型ペンタシル型ゼオライトの調製)
硝酸アンモニウム1mol/lの溶液500mlに、上
記ペンタシル型ゼオライト20gを投入し、1昼夜
攪拌しながら、還流後、遠心分離した。
これを純水で5回洗浄し、110℃で終夜乾燥後、
500℃で3時間空気焼成してプロトン型ZSM−5
ゼオライトを調製した。
(NOxの除去反応)
上記のようにして調製したプロトン型ZSM−
5ゼオライト1gと市販の0.5%白金アルミナ1
gを常圧固定床流通式反応装置に充填し(上流側
にH/ZSM−5、下流側に白金アルミナを配
置)、表1に示す反応温度で、1000ppmの一酸化
窒素(以下、「NO」と記す)と10%の酸素と
300ppmのプロパンを含むヘリウムガスを、毎分
60mlの流速で流して反応を行つた。
NOの還元分解率は生成した窒素の収率から求
め、反応ガスの分析はガスクロマトグラフを用い
て行つた。
NOの還元分解率、排出された一酸化炭素、プ
ロパン及び二酸化炭素の量を実施例1として表1
に示した。
表1から明らかなように、この場合、NOxの
還元分解が起こると同時に、プロパンがほぼ完全
に二酸化炭素に酸化されていることが判る。
比較例 1
用いる触媒を、1gのH/ZSM−5のみとし
た以外は、実施例1と同様にして反応を行つた結
果を比較例1として表1に併せて示した。
表1から明らかなように、この場合は、多量の
一酸化炭素が流出し、反応温度が300℃と低温の
場合はプロパンも多量に流出し、有害成分が残留
していることが判る。
[Industrial Application Field] The present invention is directed to the treatment of nitrogen oxides in exhaust gas in the presence of hydrocarbons or hydrocarbons remaining in the exhaust gas by adding a small amount of nitrogen oxides in exhaust gas under generally oxidizing conditions in the presence of excess oxygen. , relates to an exhaust gas purification method that removes nitrogen oxides from exhaust gas by bringing it into contact with a specific catalyst. [Conventional technology] Nitrogen oxides (hereinafter referred to as "NOx") in various exhaust gases
is harmful to health and can also cause photochemical smog and acid rain, so there is a desire to develop effective means to treat it. Conventionally, as methods for removing NOx, several methods have already been put into practical use that use catalysts to reduce NOx in exhaust gas. Examples include (a) a three-way catalyst method for gasoline-powered vehicles, and (b) a selective catalytic reduction method using ammonia for exhaust gas from large equipment sources such as boilers. In addition, other proposed methods include:
(c) As a method for removing NOx from exhaust gas using hydrocarbons, there is a method in which zeolite containing various metals is brought into contact with a gas containing NOx in the presence of hydrocarbons (Japanese Patent Laid-Open No. 63-283727, etc.). As catalysts, zeolites with various metals added have been proposed. Furthermore, the present inventors have proposed (d) a method for removing NOx in exhaust gas using hydrocarbons, in which a specific zeolite or an acidic metal oxide is brought into contact with exhaust gas containing NOx in the presence of hydrocarbons. A method has been proposed (Japanese Patent Application No. Hei 2-139340). [Problem to be solved by the invention] The method (a) above converts hydrocarbon components and carbon monoxide contained in combustion exhaust gas from automobiles into water and carbon dioxide using a catalyst, and at the same time reduces NOx to nitrogen. However, the amount of oxygen contained in NOx and
Combustion must be adjusted so that the amount of oxygen required to oxidize hydrocarbon components and carbon monoxide is chemically equal, and in systems where excess oxygen exists, such as diesel engines, , cannot be applied in principle. In addition, method (b) uses ammonia, which is a toxic and flammable high-pressure gas, so it requires huge equipment for safety reasons, and it is technically extremely difficult to apply it when the exhaust gas source is moving. be. On the other hand, method (c) is mainly targeted at gasoline-powered vehicles, and is difficult to apply under the exhaust gas conditions of diesel engines, and its activity is insufficient.
In other words, since the catalyst contains various metals as components, it is not only poisoned by sulfur oxides discharged from diesel engines, but also the added metals aggregate, resulting in a decrease in activity. It is not suitable for removing NOx from exhaust gas, and has not yet been put into practical use. In addition, method (d) can decompose and remove NOx more efficiently in the presence of hydrocarbons than conventional methods, but depending on the reaction conditions such as the catalyst used and the reaction temperature, the hydrocarbon added as a reducing agent and the oxidation intermediate The product carbon monoxide may escape. The present invention was made as a result of studying various problems that exist in (a) to (d) above, and is a method for reducing NOx in exhaust gas from various equipment, including diesel engine exhaust gas, in an oxidizing atmosphere. The purpose is to propose an exhaust gas purification method that efficiently removes harmful components and does not emit other harmful components. [Means and effects for solving the problem] In order to solve the problems existing in the above-mentioned prior art, the present inventors have conducted extensive research, and as a result, by using a specific catalyst in a specific combination, Even in exhaust gas containing sulfur oxides, it can be used at a higher rate than before without causing a decrease in activity or emitting harmful substances such as carbon monoxide.
They discovered that NOx can be removed and completed the present invention. That is, in order to achieve the above object, the exhaust gas purification method of the present invention uses proton type zeolite, alkali metal type zeolite, or acidic metal oxide in an oxidizing atmosphere containing excess oxygen and in the presence of hydrocarbons. The method is characterized in that one or more catalysts selected from the following are brought into contact with exhaust gas containing NOx, and then the exhaust gas is brought into contact with an oxidation catalyst. Furthermore, the exhaust gas purification method of the present invention is characterized in that a metal oxide treated with a compound having a sulfate radical is used as the above-mentioned acidic metal oxide. Hereinafter, the details of the method of the present invention will be explained along with its operation. In the method of the present invention, the exhaust gas to be treated is brought into contact with a reduction catalyst and an oxidation catalyst in stages. At this time, the catalyst that can be used on the upper stage side (that is, the upstream side of the exhaust gas) is a proton type zeolite, an alkali metal type zeolite, or a metal oxide with acidity such as alumina (aluminum oxide) or silica alumina. One or more selected reduction catalysts. Specifically, various zeolites such as pentasil-type zeolite, mordenite, Y-type zeolite, X-type zeolite, L-type zeolite, and silicalite can be used as the above-mentioned zeolite in the method of the present invention. The Cavan ratio of these zeolites (SiO 2 to Al 2 O 3
formula weight ratio) is not particularly limited, but
A relatively high one is preferable from the viewpoint of stability against heat and water vapor, and more preferably about 5 to 200, still more preferably about 10 to 100. These zeolites can be produced by known methods, and include silica, silica sol, silica sources such as sodium silicate, alumina gel, alumina sol,
Alumina sources such as sodium aluminate, alkaline sources such as sodium hydroxide and sodium silicate,
A raw material mixture containing water and, if necessary, an organic base such as an amine is hydrothermally synthesized, and the product is separated, washed with water, and dried to obtain an alkali metal zeolite. Complete conversion to Na type can be achieved by ion exchange. Here, the alkali metal type zeolite can be treated with an aqueous ammonium chloride or ammonium nitrate solution to obtain an ammonium type zeolite, and then calcined at a temperature range of about 400 to 700°C to obtain a pronto type zeolite. By using proton type zeolite, it becomes possible to decompose and remove NOx even more efficiently. Furthermore, in the method of the present invention, metal oxides having acidity can also be used, such as metal oxides such as alumina (Al 2 O 3 ), titanium oxide (TiO 2 ), and zirconium oxide (ZrO 2 ). , silica alumina (SiO 2・Al 2 O 3 ), silica magnesia (SiO 2・
Examples include composite oxides such as MgO), silica zirconia (SiO 2 .ZrO 2 ), and alumina titanium (Al 2 O 3 .TiO 2 ). Further, even those consisting of three or more metal oxide components can be effectively used as long as they exhibit solid acidity, and those that are highly acidic and have a large amount of acid are particularly preferred. As an example of other metal oxides, metal oxides prepared by treatment with compounds having sulfate groups can be used and can decompose NOx more efficiently than untreated metal oxides. Specific examples of compounds having a sulfate group include sulfuric acid,
Examples include ammonium sulfate, and any other compound that produces a sulfate group on the metal oxide by drying and firing after treatment can be used. The preparation of metal oxide catalysts by treatment with compounds having sulfate radicals, e.g. sulfuric acid, involves the treatment of metal oxides such as alumina (Al 2 O 3 ), titanium oxide (TiO 2 ), etc. at a specific concentration at room temperature. It can be obtained by contacting it with sulfuric acid, drying, and then calcination in the air at a specific temperature, but it is possible to obtain even higher activity by similarly treating a specific crystalline oxide or the corresponding hydroxide with sulfuric acid. A catalyst is obtained. The concentration of sulfuric acid used in the treatment varies depending on the type of oxide, but is usually about 0.01 to 10 mol/l, preferably about 0.1 to 5 mol/l, and the concentration of sulfuric acid is about 5 to 20 times the weight of the catalyst. amount and contact with metal oxide. Here, if the concentration of sulfuric acid is less than about 0.01 mol/l, contact with sulfuric acid cannot be expected to have much effect on NOx decomposition activity, and if it exceeds about 10 mol/l, metal sulfate will be formed or the catalyst structure will change. This is not very desirable as there is a risk of destruction. Furthermore, when ammonium sulfate is used as a compound having a sulfate group in the treatment, the same method as above can be used. The optimal air firing temperature also varies depending on the type of oxide, but is usually about 300 to 850℃, preferably about
The temperature is 400-700℃. If the air calcination temperature is less than approximately 300°C, compounds such as sulfuric acid used in the treatment may not be removed and catalytic active sites may not be formed; if it exceeds 850°C, the catalyst surface area may be reduced or the catalytic active sites may be destroyed. may occur. On the other hand, in the method of the present invention, the oxidation catalyst that can be used on the lower stage side (that is, the downstream side of the exhaust gas) includes, for example, platinum, palladium,
Precious metals such as rhodium, ruthenium, iridium,
Examples include catalyst components supported singly or in combination, such as base metals such as lanthanum, cerium, copper, and iron, and perovskite-type crystal structures such as lanthanum cobalt trioxide, lanthanum iron trioxide, and cobalt strontium trioxide. In this case, the supported amount of the catalyst component is about 0.01 to 2 wt% for noble metals, and about 5 to 70 wt% for base metals, based on the carrier. If the amount of each supported is small, the effect as an oxidation catalyst cannot be expected, and even if the amount of each supported exceeds the appropriate amount, the effect cannot be improved commensurately. The usage ratio of the above-mentioned reduction catalyst and oxidation catalyst, the amount of catalyst components supported on the oxidation catalyst, etc. can be selected as appropriate depending on the required performance. If the catalyst is an intermediate oxide, it is possible to use a mixture of the reduction catalyst and the oxidation catalyst, but generally the reduction catalyst is placed on the upstream side of the exhaust gas, and the oxidation catalyst is placed on the downstream side of the exhaust gas. As a specific example of purifying exhaust gas using these catalysts, a reactor with a reduction catalyst placed in the exhaust gas introduction section (first stage) and a reactor with an oxidation catalyst placed in the exhaust gas discharge part (second stage) are used. There is a method. It is also possible to arrange each catalyst in a single reactor at a ratio according to the required performance. The ratio of reduction catalyst (A) and oxidation catalyst (B) is generally
It is expressed as (A)/(B) and is used in the range of approximately 0.5/9.5 to 9.5/0.5. The above catalysts may have any shape or structure, such as powder, granule, pellet, or honeycomb shape. It is also possible to mix a non-acidic oxide such as silica, silica sol, or a molding agent such as carbon wax, oil or fat used for the purpose of molding the catalyst. Examples of the NOx-containing gas that can be treated by the method of the present invention include diesel engine exhaust gas from diesel cars and stationary diesel engines, gasoline engine exhaust gas from gasoline cars, and exhaust gas from nitric acid manufacturing plants and various combustion equipment. be able to. Removal of NOx from these exhaust gases is performed by using the catalyst and bringing the exhaust gas into contact with the catalyst in an oxidizing atmosphere in the presence of hydrocarbons. Here, the oxidizing atmosphere means to completely oxidize the carbon monoxide, hydrogen, and hydrocarbons contained in the exhaust gas, as well as the reducing substances of the hydrocarbons added as necessary in the method of the present invention, to create water and carbon dioxide. This refers to an atmosphere that contains excess oxygen than the amount of oxygen required to convert it into oxygen. For example, in the case of exhaust gas emitted from internal combustion engines such as automobiles, an atmosphere with a large air ratio (lean region) The excess oxygen rate is usually about 20 to 200%. In this oxidizing atmosphere, the catalyst disposed upstream of the exhaust gas preferentially promotes the reaction between hydrocarbons and NOx rather than the reaction between hydrocarbons and oxygen, and decomposes NOx. The hydrocarbon to be present may be the hydrocarbon remaining in the exhaust gas, but if the amount is insufficient than the amount necessary to promote the above reaction, it is necessary to add the hydrocarbon from the outside. The amount of hydrocarbons is not particularly limited, but the reduction reaction progresses more when the amount is in excess of the amount required for reductive decomposition of NOx, so it is preferable to add an excess of hydrocarbons. About 20-2000% of the theoretical amount required for decomposition, preferably about 30-1500
% excess. Here, since oxygen is present in the reaction system, the theoretical amount of necessary hydrocarbons is defined as the hydrocarbons necessary for reductive decomposition into nitrogen dioxide (NO 2 ) in the present invention. For example, when propane is used as a hydrocarbon to reductively decompose 1000 ppm of nitric oxide (NO) in the presence of oxygen, the theoretical amount of propane is 200 ppm. In general, depending on the amount of NOx in the exhaust gas, the amount of hydrocarbons to be present is approximately 50 to 50% in methane equivalent.
It is about 10000ppm. The hydrocarbon used in the present invention is not particularly limited, including gaseous and liquid hydrocarbons, and any hydrocarbon that vaporizes at the reaction temperature can be used. Specific examples of gaseous ones include hydrocarbons such as methane, ethane, propane, ethylene, propylene, and butylene, and examples of liquid ones include gasoline, diesel oil, other petroleum hydrocarbons, and alcohols. , ethers, ketones, and other oxygen-containing compounds. The reaction is carried out by preparing a reactor in which the zeolite or metal oxide is placed upstream of the exhaust gas, allowing hydrocarbons to exist in an oxidizing atmosphere, and passing the NOx-containing exhaust gas. Through the above process, NOx in the exhaust gas can be reductively decomposed, but by preparing a reactor equipped with an oxidation catalyst downstream of the exhaust gas and passing the exhaust gas continuously, NOx removal and hydrocarbon and Harmful components such as carbon monoxide can be removed by oxidizing them. The optimum reaction temperature at this time varies depending on the type of catalyst and hydrocarbon, but a temperature close to the temperature of exhaust gas is preferable because it does not require exhaust gas heating equipment, and is approximately 200 to 800 degrees Celsius, particularly approximately 300 to 600 degrees Celsius. It is valid to use within the range of . Here, when olefins are used as the added hydrocarbon, the temperature is preferably slightly lower than when paraffins are used. The reaction pressure is not particularly limited; the reaction proceeds at normal exhaust pressure, and the space velocity (SV) at which exhaust gas is introduced into the catalyst layer depends on other reaction conditions such as reaction temperature and required NOx and harmful components. There is no particular limit, but it varies depending on the removal rate of about 500~
100,000 Hr -1 , preferably in the range of about 1,000 to 70,000 Hr -1 . In addition, in the method of the present invention, when treating exhaust gas from an internal combustion engine, the catalyst is preferably placed downstream of the exhaust manifold. [Examples] Next, Examples of the method of the present invention will be described, but the method of the present invention is not limited to these Examples. Example 1 (Preparation of pentasil type zeolite) In an aqueous solution of 957 g of sodium silicate dissolved in 1200 g of water, 41 g of aluminum sulfate was dissolved in 1600 g of water.
An aqueous solution in which g, 80 g of concentrated sulfuric acid, and 360 g of sodium chloride were dissolved was gradually added and mixed over 30 minutes with stirring. Additionally, 120g of tetrapropylammonium bromide
was added to adjust the pH to 10. Pour this mixture into an autoclave and heat it to 165°C.
When the mixture was stirred for 16 hours, crystallization occurred. After separating the product, it is washed with water and dried to become a base.
ZSM- which is a pentasil type with SiO 2 /Al 2 O 3 = 62.7
5 zeolite was obtained. (Preparation of proton type pentasil type zeolite) 20 g of the above pentasil type zeolite was added to 500 ml of a solution containing 1 mol/l of ammonium nitrate, and the mixture was refluxed and centrifuged while stirring all day and night. After washing this with pure water 5 times and drying it at 110℃ overnight,
Proton type ZSM-5 is baked in air at 500℃ for 3 hours.
Zeolite was prepared. (NOx removal reaction) Proton type ZSM- prepared as above
5 zeolite 1g and commercially available 0.5% platinum alumina 1
1000 ppm of nitrogen monoxide (hereinafter referred to as "NO ) and 10% oxygen
Helium gas containing 300ppm propane every minute
The reaction was carried out at a flow rate of 60 ml. The reductive decomposition rate of NO was determined from the yield of produced nitrogen, and the reaction gas was analyzed using a gas chromatograph. Table 1 shows the reductive decomposition rate of NO and the amounts of emitted carbon monoxide, propane and carbon dioxide as Example 1.
It was shown to. As is clear from Table 1, in this case, propane is almost completely oxidized to carbon dioxide at the same time that NOx is reductively decomposed. Comparative Example 1 The reaction was carried out in the same manner as in Example 1 except that the catalyst used was only 1 g of H/ZSM-5. The results are also shown in Table 1 as Comparative Example 1. As is clear from Table 1, in this case, a large amount of carbon monoxide flows out, and when the reaction temperature is as low as 300°C, a large amount of propane also flows out, indicating that harmful components remain.
【表】
実施例 2
市販の水酸化ジルコニウム10gを濾紙上に採
り、0.5mol/lの硫酸を150ml流したあと、風乾
し、次に空気気流中600℃で3時間焼成して、硫
酸処理酸化ジルコニウムを得た。
得られた硫酸処理酸化ジルコニウム1gと市販
の0.5%白金アルミナ1gを実施例1と同様に常
圧固定床流通式反応装置に充填し、表2に示す反
応温度で、1000ppmのNOと10%の酸素と
300ppmのプロパンを含むヘリウムガスを、毎分
60mlの流速で流して反応を行つた。
NOの還元分解率の算出と排出ガスの分析は、
実施例1と同様に行つた。
その結果は、実施例2として表2に示した。
比較例 2
用いる触媒を1gの硫酸処理ジルコニウムのみ
とした以外は、実施例2と同様にして反応を行つ
た結果を比較例2として表2に併せて示した。[Table] Example 2 10 g of commercially available zirconium hydroxide was placed on a filter paper, 150 ml of 0.5 mol/l sulfuric acid was poured into it, air-dried, and then calcined in a stream of air at 600°C for 3 hours to undergo sulfuric acid treatment and oxidation. Obtained zirconium. 1 g of the obtained sulfuric acid-treated zirconium oxide and 1 g of commercially available 0.5% platinum alumina were charged into an atmospheric fixed bed flow reactor in the same manner as in Example 1, and at the reaction temperature shown in Table 2, 1000 ppm of NO and 10% of oxygen and
Helium gas containing 300ppm propane per minute
The reaction was carried out at a flow rate of 60 ml. Calculation of NO reduction decomposition rate and analysis of exhaust gas are
The same procedure as in Example 1 was carried out. The results are shown in Table 2 as Example 2. Comparative Example 2 The reaction was carried out in the same manner as in Example 2 except that only 1 g of sulfuric acid-treated zirconium was used as the catalyst. The results are also shown in Table 2 as Comparative Example 2.
【表】
実施例 3
NOx還元触媒として市販のFCC用粉状アルミ
ナ(表面積285m2/g)を用い、また酸化触媒と
して30%の酸化第二鉄をアルミナに担持させた触
媒を用いた。
酸化触媒は、38gの硝酸第二鉄(Fe(NO3)3・
9H2O)を300mlの蒸留水に溶解し、これに市販
のγ−アルミナ35gを攪拌しながら加え、14%ア
ンモニア水をPH8になるまで滴下して水酸化鉄を
アルミナ上に沈着させ、次いで濾過、水洗、乾燥
後、空気中500℃で3時間焼成することにより得
た。
上記アルミナと酸化触媒各1gを、実施例1と
同様に常圧固定床流通式反応装置に充填し、反応
温度500℃で、1000ppmのNOと10%の酸素を含
むヘリウムガスを、毎分60mlの流速で流し、添加
するプロパンの量を表3に示すように変化させて
反応を行つた。
NOの還元分解率の算出と排出ガスの分析は、
実施例1と同様に行い、その結果は実施例3とし
て表3に示した。
比較例 3
用いる触媒を1gのFCC用粉状アルミナ(表
面積285m2/g)のみとした以外は、実施例3と
同様にして反応を行つた結果を比較例3として表
3に併せて示した。[Table] Example 3 Commercially available powdered alumina for FCC (surface area 285 m 2 /g) was used as the NOx reduction catalyst, and a catalyst in which 30% ferric oxide was supported on alumina was used as the oxidation catalyst. The oxidation catalyst was 38g of ferric nitrate (Fe( NO3 ) 3 .
9H 2 O) was dissolved in 300 ml of distilled water, 35 g of commercially available γ-alumina was added thereto with stirring, 14% ammonia water was added dropwise until the pH reached 8, iron hydroxide was deposited on the alumina, and then iron hydroxide was deposited on the alumina. After filtration, washing with water, and drying, the product was calcined in air at 500°C for 3 hours. 1 g each of the above alumina and oxidation catalyst were charged into a normal pressure fixed bed flow reactor in the same manner as in Example 1, and at a reaction temperature of 500°C, helium gas containing 1000 ppm NO and 10% oxygen was supplied at 60 ml per minute. The reaction was carried out by changing the amount of propane added as shown in Table 3. Calculation of NO reduction decomposition rate and analysis of exhaust gas are
The same procedure as in Example 1 was carried out, and the results are shown in Table 3 as Example 3. Comparative Example 3 The reaction was carried out in the same manner as in Example 3, except that the catalyst used was only 1 g of powdered alumina for FCC (surface area: 285 m 2 /g). The results are also shown in Table 3 as Comparative Example 3. .
【表】
実施例 4
硫酸アルミニウム(Al2(SO4)3・16〜18H2O)
300gを1の水に溶解し、攪拌しながら24%硫
酸チタン75gを滴下し、更に14%アンモニア水を
PH9になるまで滴下した。
次に、これを95℃ウオーターバス中で数時間熟
成後、濾過し、硫酸根が検出されなくなるまで水
洗し、乾燥後、空気中500℃で3時間焼成して、
10%の酸化チタンを含有するアルミナチタニア
(Al2O3・TiO2)を得た。
得られたアルミナチタニア1gと市販の0.5%
パラジウムアルミナ1gを、実施例1と同様に常
圧固定床流通式反応装置に充填し、表4に示す反
応温度で、2000ppmのNOと10%の酸素と
600ppmのプロピレンを含むヘリウムガスを、毎
分60mlの流速で流して反応を行つた。
NOの還元分解率の算出と排出ガスの分析は、
実施例1と同様に行い、その結果は実施例4とし
て表4に示した。
比較例 4
用いる触媒を1gのアルミナチタニアのみとし
た以外は、実施例4と同様にして反応を行つた結
果を比較例4として表4に併せて示した。[Table] Example 4 Aluminum sulfate (Al 2 (SO 4 ) 3・16-18H 2 O)
Dissolve 300g in 1 water, drop 75g of 24% titanium sulfate while stirring, and then add 14% ammonia water.
The solution was added dropwise until the pH reached 9. Next, this was aged in a 95°C water bath for several hours, filtered, washed with water until no sulfate radicals were detected, dried, and then calcined in air at 500°C for 3 hours.
Alumina titania (Al 2 O 3 .TiO 2 ) containing 10% titanium oxide was obtained. 1g of obtained alumina titania and 0.5% commercially available
1 g of palladium alumina was charged into an atmospheric fixed bed flow reactor in the same manner as in Example 1, and at the reaction temperature shown in Table 4, 2000 ppm of NO and 10% oxygen were added.
The reaction was carried out by flowing helium gas containing 600 ppm of propylene at a flow rate of 60 ml per minute. Calculation of NO reduction decomposition rate and analysis of exhaust gas are
The same procedure as in Example 1 was carried out, and the results are shown in Table 4 as Example 4. Comparative Example 4 The reaction was carried out in the same manner as in Example 4 except that only 1 g of alumina titania was used as the catalyst. The results are also shown in Table 4 as Comparative Example 4.
以上詳述したように、本発明方法によれば、酸
素が過剰に存在する酸化雰囲気において、効率的
に排ガス中のNOx除去することができると共に、
一酸化炭素等のような有害成分の排出をも効果的
に防ぐことができる。
これは、本発明にかかるプロトン型ゼオライト
若しくはアルカリ金属型ゼオライト又は酸性を有
する金属酸化物が、炭化水素の存在下で、NOx
と炭化水素との反応を優先的に促進させることに
加えて、酸化触媒を用いることにより反応条件に
よつては流出することのある未反応あるいは生成
する炭化水素、一酸化炭素、あるいはその他の酸
化中間生成物を完全に酸化して、二酸化炭素及び
水蒸気とすることができるからである。
このように、本発明方法は、両者の触媒を組合
せることによつて、デイーゼル機関排ガスをはじ
め種々の設備からの排ガス中から効率よくNOx
を除去することができるのと同時に、有害成分の
排出を防ぐことができ、極めて工業的価値が高い
ものである。
As detailed above, according to the method of the present invention, NOx in exhaust gas can be efficiently removed in an oxidizing atmosphere where oxygen is present in excess, and
It is also possible to effectively prevent the emission of harmful components such as carbon monoxide. This means that the proton type zeolite or alkali metal type zeolite or the acidic metal oxide according to the present invention can generate NOx in the presence of hydrocarbons.
In addition to preferentially promoting the reaction between carbon and hydrocarbons, the use of an oxidation catalyst eliminates unreacted or generated hydrocarbons, carbon monoxide, or other oxidized substances that may flow out depending on the reaction conditions. This is because the intermediate product can be completely oxidized to carbon dioxide and water vapor. As described above, the method of the present invention efficiently removes NO x from diesel engine exhaust gas and exhaust gas from various equipment by combining both types of catalysts.
At the same time, it can prevent the discharge of harmful components, and has extremely high industrial value.
Claims (1)
素の存在下において、プロトン型ゼオライト、ア
ルカリ金属型ゼオライト又は酸性を有する金属酸
化物から選ばれる1種以上の触媒と窒素酸化物を
含む排ガスとを接触させ、次いで該排ガスを酸化
触媒に接触させることを特徴とする排ガス浄化方
法。 2 酸性を有する金属酸化物が、硫酸根を有する
化合物により処理した金属酸化物であることを特
徴とする請求項1記載の排ガス浄化方法。[Claims] 1 Nitrogen oxidation with one or more catalysts selected from proton type zeolites, alkali metal type zeolites, or acidic metal oxides in an oxidizing atmosphere containing excess oxygen and in the presence of hydrocarbons. 1. A method for purifying exhaust gas, which comprises bringing the exhaust gas into contact with an oxidation catalyst, and then bringing the exhaust gas into contact with an oxidation catalyst. 2. The exhaust gas purification method according to claim 1, wherein the acidic metal oxide is a metal oxide treated with a compound having a sulfate group.
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2204102A JPH0490826A (en) | 1990-08-01 | 1990-08-01 | Exhaust gas purification method |
EP91108690A EP0459396B1 (en) | 1990-05-28 | 1991-05-28 | Process for removing nitrogen oxides from exhaust gases |
DE69125649T DE69125649T2 (en) | 1990-05-28 | 1991-05-28 | Process for removing nitrogen oxides from exhaust gases |
KR1019910008697A KR100201748B1 (en) | 1990-05-28 | 1991-05-28 | Process for removing nitrogen oxides from exhaust gases |
US07/967,578 US5336476A (en) | 1990-05-28 | 1992-10-27 | Process for removing nitrogen oxides in exhaust gases to nitrogen |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2204102A JPH0490826A (en) | 1990-08-01 | 1990-08-01 | Exhaust gas purification method |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH0490826A JPH0490826A (en) | 1992-03-24 |
JPH0516886B2 true JPH0516886B2 (en) | 1993-03-05 |
Family
ID=16484834
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP2204102A Granted JPH0490826A (en) | 1990-05-28 | 1990-08-01 | Exhaust gas purification method |
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JP (1) | JPH0490826A (en) |
Families Citing this family (7)
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JP2691644B2 (en) * | 1991-01-08 | 1997-12-17 | 財団法人石油産業活性化センター | Method for removing nitrogen oxides in exhaust gas |
CA2138133C (en) * | 1993-04-28 | 2002-04-23 | Kazuo Tsuchitani | Method for removal of nitrogen oxides from exhaust gas |
JPH07246318A (en) * | 1994-03-11 | 1995-09-26 | Toyota Central Res & Dev Lab Inc | Method for reducing nox |
JP2006116445A (en) * | 2004-10-22 | 2006-05-11 | Japan Energy Corp | Exhaust gas purifying catalyst and manufacturing method therefor |
JP2006116444A (en) * | 2004-10-22 | 2006-05-11 | Japan Energy Corp | Exhaust gas purifying catalyst and manufacturing method therefor |
KR20090060268A (en) * | 2006-08-15 | 2009-06-11 | 이데미쓰 고산 가부시키가이샤 | Method for decomposing dinitrogen monoxide |
JP6524665B2 (en) * | 2015-01-09 | 2019-06-05 | 株式会社デンソー | Waste water treatment method and waste water treatment apparatus |
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JPS501088A (en) * | 1973-05-08 | 1975-01-08 | ||
US4297328A (en) * | 1979-09-28 | 1981-10-27 | Union Carbide Corporation | Three-way catalytic process for gaseous streams |
JPS63100919A (en) * | 1986-10-17 | 1988-05-06 | Toyota Central Res & Dev Lab Inc | Purifying method for exhaust gas and catalyst |
JPS63283727A (en) * | 1987-04-17 | 1988-11-21 | バイエル・アクチエンゲゼルシヤフト | Method and apparatus for reducing nitrogen oxide |
JPH01139145A (en) * | 1987-11-25 | 1989-05-31 | Toyota Motor Corp | Catalyst for controlling exhaust emission |
JPH02149317A (en) * | 1988-11-29 | 1990-06-07 | Ind Res Inst Japan | Removing nitrogen oxide in flue-gas |
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1990
- 1990-08-01 JP JP2204102A patent/JPH0490826A/en active Granted
Patent Citations (6)
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JPS501088A (en) * | 1973-05-08 | 1975-01-08 | ||
US4297328A (en) * | 1979-09-28 | 1981-10-27 | Union Carbide Corporation | Three-way catalytic process for gaseous streams |
JPS63100919A (en) * | 1986-10-17 | 1988-05-06 | Toyota Central Res & Dev Lab Inc | Purifying method for exhaust gas and catalyst |
JPS63283727A (en) * | 1987-04-17 | 1988-11-21 | バイエル・アクチエンゲゼルシヤフト | Method and apparatus for reducing nitrogen oxide |
JPH01139145A (en) * | 1987-11-25 | 1989-05-31 | Toyota Motor Corp | Catalyst for controlling exhaust emission |
JPH02149317A (en) * | 1988-11-29 | 1990-06-07 | Ind Res Inst Japan | Removing nitrogen oxide in flue-gas |
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