CN111097376A - Molecular sieve for adsorbing normal alkane and preparation method and application thereof - Google Patents
Molecular sieve for adsorbing normal alkane and preparation method and application thereof Download PDFInfo
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- CN111097376A CN111097376A CN201811264095.2A CN201811264095A CN111097376A CN 111097376 A CN111097376 A CN 111097376A CN 201811264095 A CN201811264095 A CN 201811264095A CN 111097376 A CN111097376 A CN 111097376A
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- 239000002808 molecular sieve Substances 0.000 title claims abstract description 150
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 title claims abstract description 150
- 150000001335 aliphatic alkanes Chemical class 0.000 title claims abstract description 15
- 238000002360 preparation method Methods 0.000 title claims abstract description 14
- 238000000034 method Methods 0.000 claims abstract description 53
- 239000000463 material Substances 0.000 claims abstract description 50
- 238000001035 drying Methods 0.000 claims abstract description 37
- 238000010438 heat treatment Methods 0.000 claims abstract description 24
- 238000007598 dipping method Methods 0.000 claims abstract description 19
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 15
- 150000001924 cycloalkanes Chemical class 0.000 claims abstract description 14
- 239000000126 substance Substances 0.000 claims abstract description 13
- 238000003763 carbonization Methods 0.000 claims abstract description 5
- 239000003463 adsorbent Substances 0.000 claims description 117
- 238000007789 sealing Methods 0.000 claims description 33
- LVZWSLJZHVFIQJ-UHFFFAOYSA-N Cyclopropane Chemical compound C1CC1 LVZWSLJZHVFIQJ-UHFFFAOYSA-N 0.000 claims description 27
- 239000007789 gas Substances 0.000 claims description 23
- 239000002994 raw material Substances 0.000 claims description 19
- 229920006395 saturated elastomer Polymers 0.000 claims description 19
- 239000011261 inert gas Substances 0.000 claims description 13
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 claims description 9
- 239000001099 ammonium carbonate Substances 0.000 claims description 9
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 claims description 7
- 238000000926 separation method Methods 0.000 claims description 7
- 235000012501 ammonium carbonate Nutrition 0.000 claims description 5
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 claims description 4
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 4
- 235000012538 ammonium bicarbonate Nutrition 0.000 claims description 4
- MNNHAPBLZZVQHP-UHFFFAOYSA-N diammonium hydrogen phosphate Chemical compound [NH4+].[NH4+].OP([O-])([O-])=O MNNHAPBLZZVQHP-UHFFFAOYSA-N 0.000 claims description 3
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 2
- 230000000274 adsorptive effect Effects 0.000 claims description 2
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 claims description 2
- 229910000387 ammonium dihydrogen phosphate Inorganic materials 0.000 claims description 2
- 239000004202 carbamide Substances 0.000 claims description 2
- 235000013877 carbamide Nutrition 0.000 claims description 2
- 235000019837 monoammonium phosphate Nutrition 0.000 claims description 2
- 235000011007 phosphoric acid Nutrition 0.000 claims description 2
- 238000001179 sorption measurement Methods 0.000 abstract description 94
- 239000012188 paraffin wax Substances 0.000 description 43
- 238000011156 evaluation Methods 0.000 description 32
- 239000011148 porous material Substances 0.000 description 29
- 230000003068 static effect Effects 0.000 description 24
- 239000000243 solution Substances 0.000 description 22
- 238000001816 cooling Methods 0.000 description 20
- 239000012086 standard solution Substances 0.000 description 20
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 19
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 15
- 239000002245 particle Substances 0.000 description 13
- 238000003756 stirring Methods 0.000 description 13
- 239000007788 liquid Substances 0.000 description 12
- 230000003213 activating effect Effects 0.000 description 11
- 239000013065 commercial product Substances 0.000 description 11
- 239000003921 oil Substances 0.000 description 11
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 10
- 238000012856 packing Methods 0.000 description 10
- 239000007864 aqueous solution Substances 0.000 description 9
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 6
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 5
- 239000005977 Ethylene Substances 0.000 description 5
- 238000005342 ion exchange Methods 0.000 description 5
- 238000005406 washing Methods 0.000 description 5
- AFABGHUZZDYHJO-UHFFFAOYSA-N 2-Methylpentane Chemical compound CCCC(C)C AFABGHUZZDYHJO-UHFFFAOYSA-N 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 239000000084 colloidal system Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- DIOQZVSQGTUSAI-UHFFFAOYSA-N decane Chemical compound CCCCCCCCCC DIOQZVSQGTUSAI-UHFFFAOYSA-N 0.000 description 4
- 229930195733 hydrocarbon Natural products 0.000 description 4
- 150000002430 hydrocarbons Chemical class 0.000 description 4
- YCOZIPAWZNQLMR-UHFFFAOYSA-N pentadecane Chemical compound CCCCCCCCCCCCCCC YCOZIPAWZNQLMR-UHFFFAOYSA-N 0.000 description 4
- 238000009738 saturating Methods 0.000 description 4
- 229910052710 silicon Inorganic materials 0.000 description 4
- 239000010703 silicon Substances 0.000 description 4
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 3
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 3
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 3
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 3
- 229910021536 Zeolite Inorganic materials 0.000 description 3
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 3
- 229960000892 attapulgite Drugs 0.000 description 3
- 229910001424 calcium ion Inorganic materials 0.000 description 3
- 229910002091 carbon monoxide Inorganic materials 0.000 description 3
- 230000008021 deposition Effects 0.000 description 3
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 229910052625 palygorskite Inorganic materials 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 238000002791 soaking Methods 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- 229910052708 sodium Inorganic materials 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 239000010457 zeolite Substances 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- UFWIBTONFRDIAS-UHFFFAOYSA-N Naphthalene Chemical compound C1=CC=CC2=CC=CC=C21 UFWIBTONFRDIAS-UHFFFAOYSA-N 0.000 description 2
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 2
- 239000012670 alkaline solution Substances 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 238000001833 catalytic reforming Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 238000005470 impregnation Methods 0.000 description 2
- 239000013067 intermediate product Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 235000006408 oxalic acid Nutrition 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000003208 petroleum Substances 0.000 description 2
- 238000011069 regeneration method Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000004230 steam cracking Methods 0.000 description 2
- 239000005995 Aluminium silicate Substances 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229920000289 Polyquaternium Polymers 0.000 description 1
- 239000004115 Sodium Silicate Substances 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 235000012211 aluminium silicate Nutrition 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- 239000013064 chemical raw material Substances 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000006837 decompression Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000002149 hierarchical pore Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- -1 normal paraffin Chemical class 0.000 description 1
- 238000000643 oven drying Methods 0.000 description 1
- 235000019353 potassium silicate Nutrition 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 229910052911 sodium silicate Inorganic materials 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- 238000005303 weighing 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
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/20—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising 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
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/30—Processes for preparing, regenerating, or reactivating
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G25/00—Refining of hydrocarbon oils in the absence of hydrogen, with solid sorbents
- C10G25/02—Refining of hydrocarbon oils in the absence of hydrogen, with solid sorbents with ion-exchange material
- C10G25/03—Refining of hydrocarbon oils in the absence of hydrogen, with solid sorbents with ion-exchange material with crystalline alumino-silicates, e.g. molecular sieves
Abstract
The invention discloses a molecular sieve for adsorbing normal alkane and a preparation method and application thereof. The preparation method of the molecular sieve for adsorbing the normal alkane comprises the following steps: (1) fully contacting a material containing cycloalkane with a 5A molecular sieve, and quickly heating to carry out carbonization treatment on the 5A molecular sieve; (2) dipping the material obtained in the step (1) by adopting a solution containing a chemical pore-enlarging agent; (3) and (3) drying and roasting the material obtained in the step (2) to obtain the modified 5A molecular sieve. The molecular sieve for adsorbing the normal alkane prepared by the method has the advantages of high adsorption capacity, high adsorption rate and the like.
Description
Technical Field
The invention relates to a molecular sieve for adsorbing normal alkane, a preparation method and application thereof, in particular to a modified 5A molecular sieve for adsorbing normal alkane, a preparation method and application thereof.
Background
The main pore canal of the 5A molecular sieve is an internal pore volume of 0.776 nm3The size of the pore diameter of the cubic sodium lattice is about 0.5 nm, and molecules with the molecular diameter of less than 0.5 nm can be allowed to pass through. Due to its shape selective adsorption, the 5A molecular sieve is widely used in the separation process of normal paraffin and non-normal hydrocarbon in various petroleum raw materials to form gas-solid adsorptionFixed bed process and simulated moving bed process of liquid-solid adsorption.
The 5A molecular sieve is a high-efficiency adsorption material for selectively separating normal paraffin in naphtha fraction. Naphtha is a mixture of various hydrocarbons such as normal paraffin, isoparaffin, naphthene and aromatic hydrocarbon. For steam cracking ethylene, different types of hydrocarbons contribute differently to the ethylene production. The yield of ethylene is highest in normal paraffin, and then in naphthene and isoparaffin, and aromatic hydrocarbon does not contribute to the generation of ethylene. On the other hand, as a catalytic reforming raw material, the reaction speed of cyclodehydrogenation of normal alkane into aromatic hydrocarbon is slow, and the conversion rate is low. Therefore, the method for analyzing the normal paraffin in the naphtha by using the 5A molecular sieve adsorbent is an effective method for fully utilizing the naphtha.
Foreign UOP company and Exxonmobil company have conducted research work for separating normal paraffins and non-normal hydrocarbons in naphtha by using a 5A molecular sieve as an adsorbent, and have achieved highly effective research results. The university of eastern China developed a 5A molecular sieve fixed bed adsorption separation process based on the concept of molecular management, which was used as raw materials for preparing ethylene by steam cracking and catalytic reforming, respectively, and the comprehensive utilization value of naphtha was improved.
CN103170304A discloses a method for preparing a 5A molecular sieve for straight-chain alkane adsorption by adopting attapulgite. Calcining attapulgite at high temperature, soaking in hydrochloric acid solution, dissolving in sodium hydroxide aqueous solution, dissolving sodium hydroxide and sodium metaaluminate in water, mixing the two liquids rapidly, stirring vigorously to obtain milky colloid, crystallizing the colloid at 80-95 deg.C for 4-6 hr, cooling, filtering, washing to pH less than 9, and oven drying to obtain 4A molecular sieve powder; and finally, carrying out ion exchange on the molecular sieve and a calcium chloride solution to obtain the 5A molecular sieve. The 5A molecular sieve has a static saturated adsorption capacity for n-decane up to 0.0716g/g, and a static saturated adsorption capacity for n-pentadecane up to 0.123 g/g. The 5A molecular sieve is prepared by cheap and easily available attapulgite resources, replaces the traditional chemical raw material method, and has good saturated adsorption capacity to straight paraffin.
CN104045095A discloses a preparation method of a 5A molecular sieve. Adding tetraethoxysilane into a sodium hydroxide aqueous solution, stirring for a period of time, adding sodium metaaluminate into the water to be fully dissolved, quickly mixing the two liquids, violently stirring to obtain a milky colloid, crystallizing the colloid at the temperature of 80-95 ℃ for 4-6 hours, cooling, filtering, washing until the pH value is less than 9, and drying to obtain 4A molecular sieve raw powder; and finally, carrying out ion exchange on the molecular sieve and a calcium chloride solution to obtain the 5A molecular sieve. The 5A molecular sieve has a static saturated adsorption capacity of n-decane up to 0.538g/g and a static saturated adsorption capacity of n-pentadecane up to 0.647 g/g. The 5A molecular sieve is prepared by adopting an organic silicon source of tetraethoxysilane as a silicon source to replace inorganic silicon source of sodium silicate, so that the pore passages of the 5A molecular sieve have diversity and the molecular sieve has good saturated adsorption capacity on straight paraffin.
CN1530167A discloses a preparation method of a high-performance pressure swing adsorption 5A molecular sieve, which comprises the following process steps: (1) mixing 80-90 parts by weight of 4A molecular sieve raw powder and 5-20 parts by weight of kaolin clay, adding 1-50 parts by weight of additive plant fiber, and granulating in a high-speed granulator. (2) And screening the granulated intermediate product according to the fineness requirement of the product, drying, and roasting at a high temperature of 200-1000 ℃. (3) Immersing the intermediate product after roasting in 4-25 wt% sodium hydroxide solution for alkali treatment, washing, and adding 2-20 wt% CaCl2Solution of Ca2+Exchanging, washing and drying, and then roasting the granular product for the second time at the temperature of 100-800 ℃ to obtain the high-performance pressure swing adsorption 5A molecular sieve product. The 5A molecular sieve prepared by the method has larger adsorption capacity, faster diffusion rate and higher mechanical strength, and is used for the aspects of pressure swing adsorption oxygen generation, hydrogen production, petroleum dewaxing and the like.
CN106861614A discloses a 5A molecular sieve adsorbent containing normal paraffin distillate oil for adsorptive separation and a preparation method thereof, the preparation method comprises the steps of adding polyquaternium as a crystallization synthesis soft template agent into a sol system mixed by a silicon source and an aluminum source, and hydrothermally synthesizing a hierarchical pore 4A molecular sieve with a micropore-mesopore structure; removing the soft template agent from the 4A molecular sieve, forming the 4A molecular sieve and a binder rolling ball into small balls with the particle size of 0.2-0.8 mm, drying, roasting, and then performing calcium ion exchange and activation to obtain a 5A molecular sieve adsorbent with a micropore-mesopore structure; in the adsorbent, the proportion of the 5A molecular sieve is 90-97 wt%, and the proportion of the binder is 3-10%. The multistage pore canal 5A molecular sieve synthesized by the method keeps higher equilibrium adsorption capacity to normal paraffin, and simultaneously remarkably improves the diffusion coefficient of the normal paraffin in the molecular sieve, thereby improving the speed of adsorption separation.
CN200510012550.6 a method for preparing a zeolite molecular sieve adsorbent with high adsorption quantity, belonging to the technical field of preparation and modification of zeolite molecular sieves. The method is characterized in that the method for preparing the zeolite molecular sieve adsorbent with high carbon monoxide adsorption quantity comprises the following steps: carrying out ion exchange on the binderless 4A molecular sieve and a calcium chloride solution to balance, washing with water, drying to prepare a 5A molecular sieve, then soaking with a dilute solution of sodium hydroxide or water glass, drying and activating to obtain the modified 5A molecular sieve adsorbent with high carbon monoxide adsorption capacity. The invention can obviously improve the adsorption performance of the 5A molecular sieve on carbon monoxide by modifying the molecular sieve by using an alkaline solution impregnation method, and the adsorption capacity of the modified adsorbent is improved by 1-15% compared with that before modification. The method is simple and easy to implement, low in cost and extremely wide in application prospect.
CN201510365330.5 discloses a modified 5A molecular sieve for removing a small amount of n-hexane in isohexane, which refers to that 5A molecular sieve to be modified is subjected to soaking dealumination treatment by using an ethanol solution of oxalic acid to obtain the modified 5A molecular sieve. Meanwhile, the invention discloses a regeneration method of the modified 5A molecular sieve after adsorbing n-hexane. The method has the advantages that: 1) the modified 5A molecular sieve has higher porosity and higher adsorption capacity to n-hexane, so that more isohexane (containing a small amount of n-hexane) can be treated; 2) the steam replacement method in the regeneration process avoids the phenomenon of carbon deposition caused by overhigh local temperature in the process of directly desorbing normal hexane by high-temperature decompression.
In summary, the adsorption capacity, adsorption rate and stability of the 5A molecular sieve adsorbent prepared in the prior art need to be further improved, and the 5A molecular sieve adsorbent impregnated with the alkaline solution or the ethanol solution of oxalic acid for modification treatment may have a certain influence on the orifice of the 5A molecular sieve adsorbent, thereby affecting the selective adsorption performance.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a molecular sieve for adsorbing normal alkane and a preparation method and application thereof. The molecular sieve for adsorbing the normal alkane prepared by the method has the advantages of high adsorption capacity, high adsorption rate and the like.
A preparation method of a molecular sieve for adsorbing normal alkane comprises the following steps:
(1) fully contacting a material containing cycloalkane with a 5A molecular sieve, and quickly heating to carry out carbonization treatment on the 5A molecular sieve;
(2) dipping the material obtained in the step (1) by adopting a solution containing a chemical pore-enlarging agent;
(3) and (3) drying and roasting the material obtained in the step (2) to obtain the modified 5A molecular sieve.
In the above method, the 5A molecular sieve may be an existing commercial product, or may be prepared according to a method well known to those skilled in the art, for example, a calcium ion solution may be used to perform ion exchange with a 4A molecular sieve to prepare a 5A molecular sieve. The 5A molecular sieve can be prepared or selected from proper particle forms according to the use requirement, such as strips, tablets, columns, spheres and the like, and is preferably spherical. Shaping can be carried out according to the general knowledge in the art.
In the method, the cycloalkane in the cycloalkane-containing material is cyclopropane, and the cyclopropane can be directly contacted with the 5A molecular sieve or contacted with the 5A molecular sieve in the form of a mixed gas of the cyclopropane and an inert gas.
In the above method, it is preferable that a mixed gas of cyclopropane and an inert gas is contacted with the 5A molecular sieve, and the concentration of cyclopropane in the mixed gas is not higher than 60 vol%, preferably not higher than 50 vol%, more preferably 10 to 40 vol%, and still more preferably 20 to 30 vol%.
In the method, the contact mode is that the 5A molecular sieve is placed in a material containing cycloalkane to enable the material containing cycloalkane to fully contact, the placing time is generally 0.1-2h, preferably 0.5-1h, then the temperature is rapidly raised to 350-650 ℃, preferably 400-500 ℃, generally the constant time is 0.5-1.5h, the temperature raising speed is 50-100 ℃/min, preferably 60-80 ℃/min under the sealing condition. The specific operation is that the 5A molecular sieve is placed in a reaction kettle or a tubular reactor, a material containing cycloalkane is introduced to replace the air in the reaction kettle or the tubular reactor, and the temperature rise treatment is carried out after the sealing placement.
In the method, the chemical pore-enlarging agent is one or more of urea, ammonium bicarbonate, ammonium carbonate, phosphoric acid, ammonium hydrogen phosphate and ammonium dihydrogen phosphate.
In the method, the solution containing the chemical pore-expanding agent is subjected to saturated dipping treatment for 0.5 to 5 hours by using a solution containing the chemical pore-expanding agent with the mass content of 15 to 50 percent at the temperature of 30 to 120 ℃, preferably 60 to 90 ℃, and is preferably subjected to saturated dipping treatment for 1 to 3 hours by using a solution containing the chemical pore-expanding agent with the mass content of 20 to 35 percent.
In the method, the 5A molecular sieve material after saturated dipping treatment is further placed in a sealing device, the temperature is raised to 200-450 ℃, preferably 250-400 ℃, and the treatment is carried out for 0.1-5h, preferably 0.5-2h, and the treatment pressure is autogenous pressure. The adsorption capacity of the modified 5A molecular sieve can be further improved by adopting a further treatment mode.
In the above method, the drying temperature may be 50 to 200 ℃, preferably 60 to 150 ℃, and more preferably 80 to 120 ℃; the drying time is 1-24 h, preferably 4-8 h; the drying can be vacuum drying, or drying under the protection of inert gas, or drying in air atmosphere; the roasting temperature is 200-800 ℃, and preferably 400-600 ℃; the roasting time is 1-24 h, preferably 4-8 h; the carbon deposit is removed by roasting in an air atmosphere or an oxygen atmosphere.
A modified 5A molecular sieve prepared by the method. The modified 5A molecular sieve is used as an adsorbent for adsorption separation of normal paraffin in naphtha, and the specific separation process is as follows: taking naphtha containing 5-45% of normal alkane as a raw material in percentage by weight, and performing reaction at the temperature of 100-300 ℃ and the pressure of 0.1-2.5 Mpa in a bed layer and at the mass space velocity of 0.2-4 h-1Under the condition of (1), the raw material is contacted with an adsorbent, wherein the used adsorbent particles are 1.6 mm-2.3 mm.
According to the method, firstly, cycloalkane with a large molecular diameter is adopted to carry out carbonization treatment on the outer surface of the 5A molecular sieve and a large pore path in the 5A molecular sieve, the purpose of the carbonization treatment is to stabilize the pore opening of the 5A molecular sieve through a small amount of carbon deposition to ensure that the subsequent pore-enlarging treatment damages the pore opening of the molecular sieve so as to influence the selective adsorption performance, then, chemical pore-enlarging agent pore-enlarging treatment is carried out on the 5A molecular sieve to enlarge and modify the internal micropore of the 5A molecular sieve, finally, the carbon deposition is burnt off to recover the normal structure of the pore path of the 5A molecular sieve, and the selective adsorption performance of the 5A molecular sieve is remarkably improved.
Detailed Description
The technical solution and the technical effects obtained by the method of the present invention will be further described below with reference to examples and comparative examples, but the following examples do not limit the method of the present invention.
(1) An appropriate amount of spherical 5A molecular sieve ((commercial product, main properties are as follows: specific surface: 680 cm)2The pore volume per gram: 0.18cm3Per g, average pore diameter: 1.7nm, particle diameter: 1.6 mm-2.3 mm), placing a 5A molecular sieve in a tubular furnace, introducing a mixed gas of cyclopropane and an inert gas to completely replace air in the tubular furnace, sealing, wherein the concentration of the cyclopropane in the mixed gas is 20 volume percent, placing for 0.5h after sealing, rapidly heating to 400 ℃ under a sealing condition, keeping constant for 0.5h, and then cooling to normal temperature at the heating speed of 60 ℃/min;
(2) saturated dipping treatment is carried out on the material in the step 1 for 1h by using an ammonium carbonate aqueous solution with the mass content of 35% at the temperature of 60 ℃;
(3) and (3) drying the material obtained in the step (2) at 120 ℃ in vacuum for 4h, roasting at 600 ℃ for 4h, and roasting in an air atmosphere to obtain the modified 5A molecular sieve.
Evaluation of static properties of modified 5A molecular sieve adsorbent: drying the modified 5A molecular sieve adsorbent, activating for 2h at 350 ℃, and cooling to room temperature for later use; at room temperature and adsorbent: the weight ratio of the adsorption liquid is 3: 5, under the condition of rapid stirring, measuring the adsorption quantity of the adsorbent to normal paraffin in the standard solution and the initial adsorption rate of 5 minutes by taking a cyclohexane solution containing 10 percent of normal hexane by weight percent as an adsorbent to evaluate the standard solution, wherein the evaluation result of the static adsorption performance of the adsorbent is shown in table 1.
Dynamic evaluation of the adsorbent on a fixed bed adsorption apparatus: the laboratory material is naphtha, wherein the total weight content of the normal paraffin of C4 to C8 is 21.25 percent; the experimental conditions are that the temperature of the adsorbent bed layer is 240 ℃, the pressure of the bed layer is 0.4Mpa, the packing content of the adsorbent is 25g, the height of the bed layer is 25cm, and the mass space velocity is 1.5h-1Under the conditions, the raw material was contacted with an adsorbent, and the adsorption amount of n-paraffins in naphtha at the breakthrough point was measured with the n-paraffin content of 1wt% in the raffinate oil as the breakthrough point, and the results are shown in Table 1.
Example 2
(1) An appropriate amount of spherical 5A molecular sieve ((commercial product, main properties are as follows: specific surface: 680 cm)2The pore volume per gram: 0.18cm3Per g, average pore diameter: 1.7nm, particle diameter: 1.6 mm-2.3 mm), placing a 5A molecular sieve in a tubular furnace, introducing a mixed gas of cyclopropane and an inert gas to completely replace air in the tubular furnace, sealing, wherein the concentration of the cyclopropane in the mixed gas is 30 volume percent, placing for 1h after sealing, rapidly heating to 500 ℃ under a sealing condition, keeping the temperature constant for 1.5h, and then cooling to normal temperature at the heating speed of 80 ℃/min;
(2) saturating and dipping the material in the step (1) for 1h by using an ammonium bicarbonate aqueous solution with the mass content of 20% at the temperature of 90 ℃;
(3) and (3) drying the material obtained in the step (2) at 80 ℃ in vacuum for 8h, roasting at 400 ℃ for 8h, and roasting in an air atmosphere to obtain the modified 5A molecular sieve.
Evaluation of static properties of modified 5A molecular sieve adsorbent: drying the modified 5A molecular sieve adsorbent, activating for 2h at 350 ℃, and cooling to room temperature for later use; at room temperature and adsorbent: the weight ratio of the adsorption liquid is 3: 5, under the condition of rapid stirring, measuring the adsorption quantity of the adsorbent to normal paraffin in the standard solution and the initial adsorption rate of 5 minutes by taking a cyclohexane solution containing 10 percent of normal hexane by weight percent as an adsorbent to evaluate the standard solution, wherein the evaluation result of the static adsorption performance of the adsorbent is shown in table 1.
Dynamic evaluation of the adsorbent on a fixed bed adsorption apparatus: laboratoryThe raw material is naphtha, wherein the total weight content of the normal paraffin of C4 to C8 is 21.25 percent; the experimental conditions are that the temperature of the adsorbent bed layer is 240 ℃, the pressure of the bed layer is 0.4Mpa, the packing content of the adsorbent is 25g, the height of the bed layer is 25cm, and the mass space velocity is 1.5h-1Under the conditions, the raw material was contacted with an adsorbent, and the adsorption amount of n-paraffins in naphtha at the breakthrough point was measured with the n-paraffin content of 1wt% in the raffinate oil as the breakthrough point, and the results are shown in Table 1.
Example 3
(1) An appropriate amount of spherical 5A molecular sieve ((commercial product, main properties are as follows: specific surface: 680 cm)2The pore volume per gram: 0.18cm3Per g, average pore diameter: 1.7nm, particle diameter: 1.6 mm-2.3 mm), placing a 5A molecular sieve in a tubular furnace, introducing a mixed gas of cyclopropane and an inert gas to completely replace air in the tubular furnace, sealing, wherein the concentration of the cyclopropane in the mixed gas is 50 volume percent, placing for 1h after sealing, rapidly heating to 550 ℃ under a sealing condition, keeping constant for 0.5h, and then cooling to normal temperature at the heating speed of 70 ℃/min;
(2) saturated impregnation treatment with 30% by mass phosphoric acid aqueous solution at 75 ℃ (material 1 for 2 hours;
(3) and (3) drying the material obtained in the step (2) at 120 ℃ in vacuum for 8h, roasting at 500 ℃ for 8h, and roasting in an air atmosphere to obtain the modified 5A molecular sieve.
Evaluation of static properties of modified 5A molecular sieve adsorbent: drying the modified 5A molecular sieve adsorbent, activating for 2h at 350 ℃, and cooling to room temperature for later use; at room temperature and adsorbent: the weight ratio of the adsorption liquid is 3: 5, under the condition of rapid stirring, measuring the adsorption quantity of the adsorbent to normal paraffin in the standard solution and the initial adsorption rate of 5 minutes by taking a cyclohexane solution containing 10 percent of normal hexane by weight percent as an adsorbent to evaluate the standard solution, wherein the evaluation result of the static adsorption performance of the adsorbent is shown in table 1.
Dynamic evaluation of the adsorbent on a fixed bed adsorption apparatus: the laboratory material is naphtha, wherein the total weight content of the normal paraffin of C4 to C8 is 21.25 percent; the experimental conditions are that the temperature of the adsorbent bed layer is 240 ℃, the pressure of the bed layer is 0.4Mpa, the packing content of the adsorbent is 25g,the height of the bed layer is 25cm, and the mass space velocity is 1.5h-1Under the conditions, the raw material was contacted with an adsorbent, and the adsorption amount of n-paraffins in naphtha at the breakthrough point was measured with the n-paraffin content of 1wt% in the raffinate oil as the breakthrough point, and the results are shown in Table 1.
Example 4
(1) An appropriate amount of spherical 5A molecular sieve ((commercial product, main properties are as follows: specific surface: 680 cm)2The pore volume per gram: 0.18cm3Per g, average pore diameter: 1.7nm, particle diameter: 1.6 mm-2.3 mm), placing a 5A molecular sieve in a tubular furnace, introducing a mixed gas of cyclopropane and an inert gas to completely replace air in the tubular furnace, sealing, wherein the concentration of the cyclopropane in the mixed gas is 40 volume percent, placing for 1h after sealing, rapidly heating to 500 ℃ under a sealing condition, keeping the temperature constant for 0.5h, and then cooling to normal temperature at the heating speed of 65 ℃/min;
(2) saturating and dipping the material in the step (1) for 1.5h at 100 ℃ by using 25 mass percent of ammonium hydrogen phosphate aqueous solution;
(3) and (3) drying the material obtained in the step (2) at 100 ℃ in vacuum for 5h, roasting at 450 ℃ for 10h, and roasting in an air atmosphere to obtain the modified 5A molecular sieve.
Evaluation of static properties of modified 5A molecular sieve adsorbent: drying the modified 5A molecular sieve adsorbent, activating for 2h at 350 ℃, and cooling to room temperature for later use; at room temperature and adsorbent: the weight ratio of the adsorption liquid is 3: 5, under the condition of rapid stirring, measuring the adsorption quantity of the adsorbent to normal paraffin in the standard solution and the initial adsorption rate of 5 minutes by taking a cyclohexane solution containing 10 percent of normal hexane by weight percent as an adsorbent to evaluate the standard solution, wherein the evaluation result of the static adsorption performance of the adsorbent is shown in table 1.
Dynamic evaluation of the adsorbent on a fixed bed adsorption apparatus: the laboratory material is naphtha, wherein the total weight content of the normal paraffin of C4 to C8 is 21.25 percent; the experimental conditions are that the temperature of the adsorbent bed layer is 240 ℃, the pressure of the bed layer is 0.4Mpa, the packing content of the adsorbent is 25g, the height of the bed layer is 25cm, and the mass space velocity is 1.5h-1Under the condition, the raw material is contacted with an adsorbent, the content of normal paraffin in raffinate oil is 1wt% as a breakthrough point, and the normal paraffin in naphtha is measuredThe adsorption of the normal paraffins at the breakthrough point is shown in Table 1.
Example 5
(1) An appropriate amount of spherical 5A molecular sieve ((commercial product, main properties are as follows: specific surface: 680 cm)2The pore volume per gram: 0.18cm3Per g, average pore diameter: 1.7nm, particle diameter: 1.6 mm-2.3 mm), placing a 5A molecular sieve in a tubular furnace, introducing a mixed gas of cyclopropane and an inert gas to completely replace air in the tubular furnace, sealing, wherein the concentration of the cyclopropane in the mixed gas is 20 volume percent, placing for 0.5h after sealing, rapidly heating to 400 ℃ under a sealing condition, keeping constant for 0.5h, and then cooling to normal temperature at the heating speed of 60 ℃/min;
(2) saturated dipping the material in the step 1 for 1h by using 35% ammonium carbonate aqueous solution at the temperature of 60 ℃, placing the 5A molecular sieve material subjected to saturated dipping treatment into a sealing device, heating to 250 ℃ and treating for 2h, wherein the treatment pressure is autogenous pressure;
(3) and (3) drying the material obtained in the step (2) at 120 ℃ in vacuum for 4h, roasting at 600 ℃ for 4h, and roasting in an air atmosphere to obtain the modified 5A molecular sieve.
Evaluation of static properties of modified 5A molecular sieve adsorbent: drying the modified 5A molecular sieve adsorbent, activating for 2h at 350 ℃, and cooling to room temperature for later use; at room temperature and adsorbent: the weight ratio of the adsorption liquid is 3: 5, under the condition of rapid stirring, measuring the adsorption quantity of the adsorbent to normal paraffin in the standard solution and the initial adsorption rate of 5 minutes by taking a cyclohexane solution containing 10 percent of normal hexane by weight percent as an adsorbent to evaluate the standard solution, wherein the evaluation result of the static adsorption performance of the adsorbent is shown in table 1.
Dynamic evaluation of the adsorbent on a fixed bed adsorption apparatus: the laboratory material is naphtha, wherein the total weight content of the normal paraffin of C4 to C8 is 21.25 percent; the experimental conditions are that the temperature of the adsorbent bed layer is 240 ℃, the pressure of the bed layer is 0.4Mpa, the packing content of the adsorbent is 25g, the height of the bed layer is 25cm, and the mass space velocity is 1.5h-1Under the condition, the raw material is contacted with an adsorbent, the content of normal paraffin in raffinate oil is 1wt% as a breakthrough point, and the adsorption quantity of the normal paraffin in naphtha at the breakthrough point is measured, and the result is shown in a table1。
Example 6
(1) An appropriate amount of spherical 5A molecular sieve ((commercial product, main properties are as follows: specific surface: 680 cm)2The pore volume per gram: 0.18cm3Per g, average pore diameter: 1.7nm, particle diameter: 1.6 mm-2.3 mm), placing a 5A molecular sieve in a tubular furnace, introducing a mixed gas of cyclopropane and an inert gas to completely replace air in the tubular furnace, sealing, wherein the concentration of the cyclopropane in the mixed gas is 30 volume percent, placing for 1h after sealing, rapidly heating to 500 ℃ under a sealing condition, keeping the temperature constant for 1.5h, and then cooling to normal temperature at the heating speed of 80 ℃/min;
(2) saturating and dipping the material in the step (1) for 1h at 90 ℃ by using 20 mass percent ammonium bicarbonate aqueous solution, placing the 5A molecular sieve material subjected to saturation and dipping treatment into a sealing device, heating to 400 ℃ and treating for 0.5h, wherein the treatment pressure is autogenous pressure;
(3) and (3) drying the material obtained in the step (2) at 80 ℃ in vacuum for 8h, roasting at 400 ℃ for 8h, and roasting in an air atmosphere to obtain the modified 5A molecular sieve.
Evaluation of static properties of modified 5A molecular sieve adsorbent: drying the modified 5A molecular sieve adsorbent, activating for 2h at 350 ℃, and cooling to room temperature for later use; at room temperature and adsorbent: the weight ratio of the adsorption liquid is 3: 5, under the condition of rapid stirring, measuring the adsorption quantity of the adsorbent to normal paraffin in the standard solution and the initial adsorption rate of 5 minutes by taking a cyclohexane solution containing 10 percent of normal hexane by weight percent as an adsorbent to evaluate the standard solution, wherein the evaluation result of the static adsorption performance of the adsorbent is shown in table 1.
Dynamic evaluation of the adsorbent on a fixed bed adsorption apparatus: the laboratory material is naphtha, wherein the total weight content of the normal paraffin of C4 to C8 is 21.25 percent; the experimental conditions are that the temperature of the adsorbent bed layer is 240 ℃, the pressure of the bed layer is 0.4Mpa, the packing content of the adsorbent is 25g, the height of the bed layer is 25cm, and the mass space velocity is 1.5h-1Under the conditions, the raw material was contacted with an adsorbent, and the adsorption amount of n-paraffins in naphtha at the breakthrough point was measured with the n-paraffin content of 1wt% in the raffinate oil as the breakthrough point, and the results are shown in Table 1.
Example 7
(1) An appropriate amount of spherical 5A molecular sieve ((commercial product, main properties are as follows: specific surface: 680 cm)2The pore volume per gram: 0.18cm3Per g, average pore diameter: 1.7nm, particle diameter: 1.6 mm-2.3 mm), placing a 5A molecular sieve in a tubular furnace, introducing a mixed gas of cyclopropane and an inert gas to completely replace air in the tubular furnace, sealing, wherein the concentration of the cyclopropane in the mixed gas is 50 volume percent, placing for 1h after sealing, rapidly heating to 550 ℃ under a sealing condition, keeping constant for 0.5h, and then cooling to normal temperature at the heating speed of 70 ℃/min;
(2) saturating and dipping the materials by using a phosphoric acid aqueous solution with the mass content of 30% at the temperature of 75 ℃ (1 material is placed in a sealing device for 2 hours, the 5A molecular sieve material after saturated dipping treatment is heated to 300 ℃ for treatment for 1 hour, and the treatment pressure is autogenous pressure;
(3) and (3) drying the material obtained in the step (2) at 120 ℃ in vacuum for 8h, roasting at 500 ℃ for 8h, and roasting in an air atmosphere to obtain the modified 5A molecular sieve.
Evaluation of static properties of modified 5A molecular sieve adsorbent: drying the modified 5A molecular sieve adsorbent, activating for 2h at 350 ℃, and cooling to room temperature for later use; at room temperature and adsorbent: the weight ratio of the adsorption liquid is 3: 5, under the condition of rapid stirring, measuring the adsorption quantity of the adsorbent to normal paraffin in the standard solution and the initial adsorption rate of 5 minutes by taking a cyclohexane solution containing 10 percent of normal hexane by weight percent as an adsorbent to evaluate the standard solution, wherein the evaluation result of the static adsorption performance of the adsorbent is shown in table 1.
Dynamic evaluation of the adsorbent on a fixed bed adsorption apparatus: the laboratory material is naphtha, wherein the total weight content of the normal paraffin of C4 to C8 is 21.25 percent; the experimental conditions are that the temperature of the adsorbent bed layer is 240 ℃, the pressure of the bed layer is 0.4Mpa, the packing content of the adsorbent is 25g, the height of the bed layer is 25cm, and the mass space velocity is 1.5h-1Under the conditions, the raw material was contacted with an adsorbent, and the adsorption amount of n-paraffins in naphtha at the breakthrough point was measured with the n-paraffin content of 1wt% in the raffinate oil as the breakthrough point, and the results are shown in Table 1.
Comparative example 1 (No Dip treatment Process)
(1) An appropriate amount of spherical 5A molecular sieve ((commercial product, main properties are as follows: specific surface: 680 cm)2The pore volume per gram: 0.18cm3Per g, average pore diameter: 1.7nm, particle diameter: 1.6 mm-2.3 mm), placing a 5A molecular sieve in a tubular furnace, introducing a mixed gas of cyclopropane and an inert gas to completely replace air in the tubular furnace, sealing, wherein the concentration of the cyclopropane in the mixed gas is 20 volume percent, placing for 0.5h after sealing, rapidly heating to 400 ℃ under a sealing condition, keeping constant for 0.5h, and then cooling to normal temperature at the heating speed of 60 ℃/min;
(2) and (2) drying the material obtained in the step (1) at 120 ℃ in vacuum for 4h, roasting at 600 ℃ for 4h, and roasting in an air atmosphere to obtain the modified 5A molecular sieve.
Evaluation of static properties of modified 5A molecular sieve adsorbent: drying the modified 5A molecular sieve adsorbent, activating for 2h at 350 ℃, and cooling to room temperature for later use; at room temperature and adsorbent: the weight ratio of the adsorption liquid is 3: 5, under the condition of rapid stirring, measuring the adsorption quantity of the adsorbent to normal paraffin in the standard solution and the initial adsorption rate of 5 minutes by taking a cyclohexane solution containing 10 percent of normal hexane by weight percent as an adsorbent to evaluate the standard solution, wherein the evaluation result of the static adsorption performance of the adsorbent is shown in table 1.
Dynamic evaluation of the adsorbent on a fixed bed adsorption apparatus: the laboratory material is naphtha, wherein the total weight content of the normal paraffin of C4 to C8 is 21.25 percent; the experimental conditions are that the temperature of the adsorbent bed layer is 240 ℃, the pressure of the bed layer is 0.4Mpa, the packing content of the adsorbent is 25g, the height of the bed layer is 25cm, and the mass space velocity is 1.5h-1Under the conditions, the raw material was contacted with an adsorbent, and the adsorption amount of n-paraffins in naphtha at the breakthrough point was measured with the n-paraffin content of 1wt% in the raffinate oil as the breakthrough point, and the results are shown in Table 1.
Comparative example 2 (non-charring Process)
(1) An appropriate amount of spherical 5A molecular sieve ((commercial product, main properties are as follows: specific surface: 680 cm)2The pore volume per gram: 0.18cm3Per g, average pore diameter: 1.7nm, particle diameter: 1.6 mm-2.3 mm) at 60 deg.C, saturated with 35% ammonium carbonate aqueous solutionDipping the material in the step 1 for 1 hour;
(2) and (2) drying the material obtained in the step (1) at 120 ℃ in vacuum for 4h, roasting at 600 ℃ for 4h, and roasting in an air atmosphere to obtain the modified 5A molecular sieve.
Evaluation of static properties of modified 5A molecular sieve adsorbent: drying the modified 5A molecular sieve adsorbent, activating for 2h at 350 ℃, and cooling to room temperature for later use; at room temperature and adsorbent: the weight ratio of the adsorption liquid is 3: 5, under the condition of rapid stirring, measuring the adsorption quantity of the adsorbent to normal paraffin in the standard solution and the initial adsorption rate of 5 minutes by taking a cyclohexane solution containing 10 percent of normal hexane by weight percent as an adsorbent to evaluate the standard solution, wherein the evaluation result of the static adsorption performance of the adsorbent is shown in table 1.
Dynamic evaluation of the adsorbent on a fixed bed adsorption apparatus: the laboratory material is naphtha, wherein the total weight content of the normal paraffin of C4 to C8 is 21.25 percent; the experimental conditions are that the temperature of the adsorbent bed layer is 240 ℃, the pressure of the bed layer is 0.4Mpa, the packing content of the adsorbent is 25g, the height of the bed layer is 25cm, and the mass space velocity is 1.5h-1Under the conditions, the raw material was contacted with an adsorbent, and the adsorption amount of n-paraffins in naphtha at the breakthrough point was measured with the n-paraffin content of 1wt% in the raffinate oil as the breakthrough point, and the results are shown in Table 1.
Comparative example 3
Weighing appropriate amount of spherical 5A molecular sieve for direct evaluation (commercial product, main properties are as follows: specific surface: 680 cm)2The pore volume per gram: 0.18cm3Per g, average pore diameter: 1.7nm, particle diameter: 1.6 mm-2.3 mm).
Evaluation of static properties of 5A molecular sieve adsorbent: drying the 5A molecular sieve adsorbent, activating for 2h at 350 ℃, and cooling to room temperature for later use; at room temperature and adsorbent: the weight ratio of the adsorption liquid is 3: 5, under the condition of rapid stirring, measuring the adsorption quantity of the adsorbent to normal paraffin in the standard solution and the initial adsorption rate of 5 minutes by taking a cyclohexane solution containing 10 percent of normal hexane by weight percent as an adsorbent to evaluate the standard solution, wherein the evaluation result of the static adsorption performance of the adsorbent is shown in table 1.
Dynamic evaluation of the adsorbent on a fixed bed adsorption apparatus: laboratoryThe raw material is naphtha, wherein the total weight content of the normal paraffin of C4 to C8 is 21.25 percent; the experimental conditions are that the temperature of the adsorbent bed layer is 240 ℃, the pressure of the bed layer is 0.4Mpa, the packing content of the adsorbent is 25g, the height of the bed layer is 25cm, and the mass space velocity is 1.5h-1Under the conditions, the raw material was contacted with an adsorbent, and the adsorption amount of n-paraffins in naphtha at the breakthrough point was measured with the n-paraffin content of 1wt% in the raffinate oil as the breakthrough point, and the results are shown in Table 1.
TABLE 1 evaluation results
Claims (19)
1. A preparation method of a molecular sieve for adsorbing normal alkane is characterized by comprising the following steps: the method comprises the following steps:
(1) fully contacting a material containing cycloalkane with a 5A molecular sieve, and quickly heating to carry out carbonization treatment on the 5A molecular sieve;
(2) dipping the material obtained in the step (1) by adopting a solution containing a chemical pore-enlarging agent;
(3) and (3) drying and roasting the material obtained in the step (2) to obtain the modified 5A molecular sieve.
2. The method of claim 1, wherein: the 5A molecular sieves are currently commercially available products or are prepared according to methods well known to those skilled in the art.
3. The method of claim 2, wherein: the 5A molecular sieve is one of a strip, a sheet, a column or a sphere.
4. The method of claim 1, wherein: the cycloalkane in the cycloalkane-containing material is cyclopropane, and the cyclopropane is directly contacted with the 5A molecular sieve or the mixed gas of the cyclopropane and the inert gas is contacted with the 5A molecular sieve.
5. The method of claim 4, wherein: a mixed gas of cyclopropane and inert gas is contacted with the 5A molecular sieve, and the concentration of the cyclopropane in the mixed gas is not higher than 60% by volume.
6. The method of claim 5, wherein: the concentration of cyclopropane in the mixed gas is 10-40 vol%.
7. The method of claim 1, wherein: the contact mode is that the 5A molecular sieve is placed in a material containing cycloalkane to enable the material containing cycloalkane to be in full contact, the placing time is 0.1-2h, then the temperature is rapidly raised to 350-650 ℃ under a sealed condition, the constant time is 0.5-1.5h, and the temperature raising speed is 50-100 ℃/min.
8. The method of claim 7, wherein: standing for 0.5-1h, and then rapidly heating to 400-500 ℃ under a sealed condition at a heating rate of 60-80 ℃/min.
9. The method of claim 7, wherein: placing the 5A molecular sieve in a reaction kettle or a tubular reactor, introducing a material containing cycloalkane to replace air in the reaction kettle or the tubular reactor, sealing and placing, and then heating.
10. The method of claim 1, wherein: the chemical pore-enlarging agent is one or more of urea, ammonium bicarbonate, ammonium carbonate, phosphoric acid, ammonium hydrogen phosphate and ammonium dihydrogen phosphate.
11. The method of claim 1, wherein: the solution containing the chemical pore-expanding agent is subjected to saturated dipping treatment for 0.5-5 h by using a solution containing the chemical pore-expanding agent with the mass content of 15-50% at the temperature of 30-120 ℃.
12. The method of claim 11, wherein: the solution containing the chemical pore-expanding agent is subjected to saturated dipping treatment for 1-3 hours at the temperature of 60-90 ℃ by using a solution containing the chemical pore-expanding agent and with the mass content of 20-35%.
13. The method of claim 11, wherein: the 5A molecular sieve material after saturated dipping treatment is put into a sealing device and is heated to 200-450 ℃ for treatment for 0.1-5 h.
14. The method of claim 13, wherein: the 5A molecular sieve material after saturated dipping treatment is put into a sealing device and is heated to 250-400 ℃ for treatment for 0.5-2 h.
15. The method of claim 1, wherein: the drying temperature is 50-200 ℃; the drying time is 1-24 h; the roasting temperature is 200-800 ℃; the roasting time is 1-24 h.
16. The method of claim 15, wherein: the drying temperature is 60-150 ℃; the drying time is 4-8 h; the roasting temperature is 400-600 ℃; the roasting time is 4-8 h.
17. A molecular sieve for adsorbing n-alkanes made by the process of any of claims 1-16.
18. The molecular sieve for adsorbing n-paraffins as claimed in claim 17 is used as an adsorbent for the adsorptive separation of n-paraffins from naphtha.
19. Use according to claim 18, characterized in that: taking naphtha containing 5-45% of normal alkane as a raw material in percentage by weight, and performing reaction at the temperature of 100-300 ℃ and the pressure of 0.1-2.5 Mpa in a bed layer and at the mass space velocity of 0.2-4 h-1Under the conditions of (1), the raw material is contacted with the adsorbent.
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| CN104888695A (en) * | 2015-06-29 | 2015-09-09 | 岳阳金瀚高新技术股份有限公司 | Modified 5A molecular sieve used for removing small-amount n-hexane from isohexane and regeneration method thereof |
| CN106669773A (en) * | 2015-11-11 | 2017-05-17 | 中国石油化工股份有限公司 | Method for modifying Y-type molecular sieve |
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| CN104888695A (en) * | 2015-06-29 | 2015-09-09 | 岳阳金瀚高新技术股份有限公司 | Modified 5A molecular sieve used for removing small-amount n-hexane from isohexane and regeneration method thereof |
| CN106669773A (en) * | 2015-11-11 | 2017-05-17 | 中国石油化工股份有限公司 | Method for modifying Y-type molecular sieve |
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