CN112723371B - Modified 5A molecular sieve and preparation method and application thereof - Google Patents
Modified 5A molecular sieve and preparation method and application thereof Download PDFInfo
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- 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 116
- 239000002808 molecular sieve Substances 0.000 title claims abstract description 114
- 238000002360 preparation method Methods 0.000 title claims abstract description 15
- 238000010335 hydrothermal treatment Methods 0.000 claims abstract description 67
- 238000000034 method Methods 0.000 claims abstract description 50
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 40
- 239000000463 material Substances 0.000 claims abstract description 31
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 26
- 238000001035 drying Methods 0.000 claims abstract description 22
- 238000010438 heat treatment Methods 0.000 claims abstract description 21
- 239000003463 adsorbent Substances 0.000 claims description 51
- 238000007789 sealing Methods 0.000 claims description 29
- LVZWSLJZHVFIQJ-UHFFFAOYSA-N Cyclopropane Chemical compound C1CC1 LVZWSLJZHVFIQJ-UHFFFAOYSA-N 0.000 claims description 26
- 239000002994 raw material Substances 0.000 claims description 21
- 239000007789 gas Substances 0.000 claims description 20
- 239000011261 inert gas Substances 0.000 claims description 13
- 229910021529 ammonia Inorganic materials 0.000 claims description 12
- 238000000926 separation method Methods 0.000 claims description 9
- 239000000203 mixture Substances 0.000 claims description 7
- 238000006243 chemical reaction Methods 0.000 claims description 6
- 150000001924 cycloalkanes Chemical class 0.000 claims description 6
- 239000013065 commercial product Substances 0.000 claims description 2
- 230000000274 adsorptive effect Effects 0.000 claims 1
- 238000001179 sorption measurement Methods 0.000 abstract description 58
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 abstract description 30
- 230000000694 effects Effects 0.000 abstract description 5
- 239000011148 porous material Substances 0.000 description 28
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 24
- 230000035515 penetration Effects 0.000 description 16
- 238000001291 vacuum drying Methods 0.000 description 16
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 15
- 239000003921 oil Substances 0.000 description 11
- 239000002245 particle Substances 0.000 description 11
- 238000001816 cooling Methods 0.000 description 10
- 238000003795 desorption Methods 0.000 description 10
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 10
- 229910052757 nitrogen Inorganic materials 0.000 description 10
- 150000001335 aliphatic alkanes Chemical class 0.000 description 9
- 238000011156 evaluation Methods 0.000 description 9
- 238000011049 filling Methods 0.000 description 9
- 238000010926 purge Methods 0.000 description 9
- 238000005303 weighing Methods 0.000 description 8
- 229920006395 saturated elastomer Polymers 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- AFABGHUZZDYHJO-UHFFFAOYSA-N 2-Methylpentane Chemical compound CCCC(C)C AFABGHUZZDYHJO-UHFFFAOYSA-N 0.000 description 5
- 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
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 4
- 239000000084 colloidal system Substances 0.000 description 4
- DIOQZVSQGTUSAI-UHFFFAOYSA-N decane Chemical compound CCCCCCCCCC DIOQZVSQGTUSAI-UHFFFAOYSA-N 0.000 description 4
- 238000009792 diffusion process Methods 0.000 description 4
- 229910001873 dinitrogen Inorganic materials 0.000 description 4
- 229930195733 hydrocarbon Natural products 0.000 description 4
- 150000002430 hydrocarbons Chemical class 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- YCOZIPAWZNQLMR-UHFFFAOYSA-N pentadecane Chemical compound CCCCCCCCCCCCCCC YCOZIPAWZNQLMR-UHFFFAOYSA-N 0.000 description 4
- 229910052710 silicon Inorganic materials 0.000 description 4
- 239000010703 silicon Substances 0.000 description 4
- 230000003068 static effect Effects 0.000 description 4
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 3
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- 229960000892 attapulgite Drugs 0.000 description 3
- 239000011230 binding agent Substances 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 230000000052 comparative effect 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
- 238000003756 stirring Methods 0.000 description 3
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical group [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 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 2
- 239000004115 Sodium Silicate Substances 0.000 description 2
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 2
- 229910021536 Zeolite Inorganic materials 0.000 description 2
- 230000003213 activating effect Effects 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000001354 calcination Methods 0.000 description 2
- 229910001424 calcium ion Inorganic materials 0.000 description 2
- 229910002091 carbon monoxide Inorganic materials 0.000 description 2
- 238000001833 catalytic reforming Methods 0.000 description 2
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 239000013067 intermediate product Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 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
- 239000011734 sodium Substances 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 2
- 229910052911 sodium silicate Inorganic materials 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000002336 sorption--desorption measurement Methods 0.000 description 2
- 238000004230 steam cracking Methods 0.000 description 2
- 239000010457 zeolite Substances 0.000 description 2
- 239000005995 Aluminium silicate Substances 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 description 1
- 229920000289 Polyquaternium Polymers 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
- 239000012670 alkaline solution 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
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 210000004556 brain Anatomy 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000010000 carbonizing Methods 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000013064 chemical raw material Substances 0.000 description 1
- 239000004927 clay 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
- 230000006837 decompression Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006356 dehydrogenation reaction Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000001027 hydrothermal synthesis Methods 0.000 description 1
- 238000005470 impregnation Methods 0.000 description 1
- 239000012535 impurity Substances 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
- -1 normal paraffins Chemical class 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B39/00—Compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites; Their preparation; After-treatment, e.g. ion-exchange or dealumination
- C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
- C01B39/14—Type A
-
- 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
- B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
- B01J20/16—Alumino-silicates
- B01J20/18—Synthetic zeolitic molecular sieves
- B01J20/186—Chemical treatments in view of modifying the properties of the sieve, e.g. increasing the stability or the activity, also decreasing the activity
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B39/00—Compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites; Their preparation; After-treatment, e.g. ion-exchange or dealumination
- C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
- C01B39/026—After-treatment
-
- 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
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Crystallography & Structural Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
Abstract
The invention discloses a preparation method of a modified 5A molecular sieve, which comprises the following steps: (1) Fully contacting a material containing cycloparaffin with a 5A molecular sieve, and quickly heating to carbonize the 5A molecular sieve; (2) carrying out hydrothermal treatment on the material obtained in the step (1); (3) Drying and roasting the material treated in the step (2); (4) And (3) treating the treated material in the step (3) in an ammonia gas and water vapor mixed atmosphere, and drying and roasting the treated material to obtain the modified 5A molecular sieve. The modified 5A molecular sieve prepared by the method not only has high adsorption capacity, but also has higher adsorption effect on monomethyl isoparaffin.
Description
Technical Field
The invention relates to a modified 5A molecular sieve and a preparation method and application thereof, in particular to a modified 5A molecular sieve with high adsorption capacity and a preparation method and application thereof.
Background
The main pore canal of the 5A molecular sieve is an internal pore volume of 0.776 nm 3 The pore size is about 0.5. 0.5 nm and allows molecules having a molecular diameter of less than 0.5. 0.5 nm to pass through. Because of its shape selective adsorption, 5A molecular sieves are widely used in the separation process of normal paraffins and non-normal hydrocarbons in various petroleum feedstocks, forming a fixed bed process for gas-solid adsorption and a simulated moving bed process for liquid-solid adsorption.
The 5A molecular sieve is a high-efficiency adsorption material for selectively separating normal paraffins in naphtha fraction. Naphtha is composed of a mixture of various hydrocarbons such as normal paraffins, isoparaffins, naphthenes and aromatics. For steam cracking ethylene, the contribution of different kinds of hydrocarbons to ethylene production is different in size. The ethylene yield of normal paraffins is highest, followed by naphthenes, isoparaffins, and aromatics do not contribute to ethylene production. On the other hand, as a catalytic reforming raw material, the reaction rate of cyclized dehydrogenation of normal paraffins to aromatics is slow, and the conversion rate is low. Therefore, the 5A molecular sieve adsorbent is used for analyzing normal paraffins in the naphtha, and is an effective method for fully utilizing the naphtha.
The foreign UOP company and the Exxonmobil company take 5A molecular sieves as adsorbents to carry out research work of separating normal paraffins from non-normal hydrocarbons in naphtha, and have achieved remarkable research results. Based on the principle of molecular management, the university of eastern China develops a 5A molecular sieve fixed bed adsorption separation process which is respectively used as raw materials for preparing ethylene by steam cracking and for catalytic reforming, and improves the comprehensive utilization value of naphtha.
CN103170304a discloses a method related to the preparation of 5A molecular sieve for linear alkane adsorption using attapulgite. Calcining attapulgite at high temperature, soaking with hydrochloric acid solution, fully dissolving with sodium hydroxide aqueous solution, fully dissolving sodium hydroxide and sodium metaaluminate in water, rapidly mixing the two liquids, vigorously stirring to obtain milky colloid, crystallizing the colloid at 80-95 ℃ for 4-6h, cooling, filtering, washing to pH less than 9, and drying to obtain 4A molecular sieve raw powder; and finally, carrying out ion exchange on the mixture and a calcium chloride solution to obtain the 5A molecular sieve. The static saturated adsorption capacity of the 5A molecular sieve to n-decane can reach 0.0716g/g, and the static saturated adsorption capacity to n-pentadecane can reach 0.123g/g. The 5A molecular sieve is prepared from cheap and easily available attapulgite resources, replaces the traditional chemical raw material method, and has good saturated adsorption capacity on straight-chain alkane.
CN104045095A discloses a preparation method of 5A molecular sieve. Adding ethyl orthosilicate into a sodium hydroxide aqueous solution, stirring for a period of time, adding sodium metaaluminate into water for full dissolution, rapidly mixing the two liquids, vigorously stirring to obtain milky colloid, crystallizing the colloid at 80-95 ℃ for 4-6 hours, cooling, filtering, washing to pH less than 9, and drying to obtain 4A molecular sieve raw powder; and finally, carrying out ion exchange on the mixture and a calcium chloride solution to obtain the 5A molecular sieve. The static saturated adsorption capacity of the 5A molecular sieve to n-decane can reach 0.538g/g, and the static saturated adsorption capacity to n-pentadecane can reach 0.647g/g. The organic silicon source ethyl orthosilicate is used as a silicon source to prepare the 5A molecular sieve, and the inorganic silicon source sodium silicate is replaced, so that the pore canal of the 5A molecular sieve has diversity, and the molecular sieve has good saturated adsorption capacity to straight-chain alkane.
CN1530167a discloses a preparation method of high-performance pressure swing adsorption 5A molecular sieve, which comprises the following steps: (1) 80-90 parts by weight of 4A molecular sieve raw powder and 5-20 parts by weight of kaolin clay are mixed, 1-50 parts by weight of additive plant fiber is added, and the mixture is granulated in a high-speed granulator. (2) Sieving the granulated intermediate product according to the fineness requirement of the product, drying and roasting at 200-1000 ℃. (3) Immersing the calcined intermediate product in 4-25 wt.% sodium hydroxide solution for alkali treatment, washing, and adding 2-20 wt.% CaCl 2 Solution Ca 2+ Exchanging, washing and drying, and then carrying out secondary roasting on the granular product at 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, quicker diffusion rate and higher mechanical strength, and is used for pressure swing adsorption oxygen production, hydrogen production, petroleum dewaxing and other aspects.
CN106861614A discloses a 5A molecular sieve adsorbent containing n-alkane distillate oil for adsorption separation and a preparation method thereof, wherein the preparation method takes polyquaternium as a crystallization synthesis soft template agent to be added into a sol system mixed by a silicon source and an aluminum source, and a multistage pore 4A molecular sieve with a micropore-mesopore structure is synthesized by hydrothermal method; removing the soft template agent from the 4A molecular sieve, forming the soft template agent and the binder into small balls with the particle size of 0.2-0.8 mm by rolling balls, drying, roasting, performing calcium ion exchange, and activating to obtain the 5A molecular sieve adsorbent with a micropore-mesopore structure; the proportion of the 5A molecular sieve in the adsorbent is 90-97 wt% and the proportion of the binder is 3-10%. The multistage pore passage 5A molecular sieve synthesized by the method has higher equilibrium adsorption capacity on normal alkane, and simultaneously obviously improves the diffusion coefficient of the normal alkane in the molecular sieve, thereby improving the adsorption separation rate.
CN200510012550.6 is a preparation method of high adsorption quantity zeolite molecular sieve adsorbent, belonging to the technical field of zeolite molecular sieve preparation and modification. The method is characterized by comprising the following steps of: and (3) carrying out ion exchange on the non-binder type 4A molecular sieve and a calcium chloride solution to balance, washing with water, drying to obtain a 5A molecular sieve, then soaking with a dilute solution of sodium hydroxide or sodium silicate, drying and activating to obtain the modified 5A molecular sieve adsorbent with high carbon monoxide adsorption quantity. The adsorption performance of the 5A molecular sieve to carbon monoxide can be obviously improved by modifying the 5A molecular sieve by 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 operate, 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 is obtained by soaking the 5A molecular sieve to be modified in ethanol solution of oxalic acid for dealumination treatment. Meanwhile, the invention discloses a regeneration method of the modified 5A molecular sieve after n-hexane is adsorbed. The method has the beneficial effects that: 1) The modified 5A molecular sieve has larger porosity and larger adsorption capacity to n-hexane, so that more isohexane (containing a small amount of n-hexane) can be treated; 2) The water vapor replacement method in the regeneration process avoids the phenomenon of carbon deposition caused by overhigh local temperature in the direct high-temperature decompression desorption of normal hexane.
The 5A molecular sieve synthesized by the traditional method only has a micropore channel structure. The slower molecular diffusion rate and longer molecular diffusion path in the micropores result in low utilization rate in the activity inside the molecular sieve crystal, and greatly limit the rate of the adsorption/desorption process, so that the cycle period of adsorption/desorption is longer. The molecular sieve is easy to be coked and blocked by impurities in the use process of the molecular sieve, so that a large number of pore channels are invalid, and the effective utilization rate and the service life of the molecular sieve are seriously influenced. Meanwhile, the micro-pore system with smaller pore diameter has the problem of poor separation effect on low-octane components formed by monomethyl isoparaffin.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a modified 5A molecular sieve, and a preparation method and application thereof. The modified 5A molecular sieve prepared by the method not only has high adsorption capacity, but also has higher adsorption effect on monomethyl isoparaffin.
A preparation method of a modified 5A molecular sieve comprises the following steps:
(1) Fully contacting a material containing cycloparaffin with a 5A molecular sieve, and quickly heating to carbonize the 5A molecular sieve;
(2) Carrying out hydrothermal treatment on the material obtained in the step (1);
(3) Drying and roasting the material treated in the step (2);
(4) And (3) treating the treated material in the step (3) in an ammonia gas and water vapor mixed atmosphere, and drying and roasting the treated material 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 the 4A molecular sieve to prepare the 5A molecular sieve. The 5A molecular sieve can be prepared or selected into proper particle forms according to the use requirement, such as bar, sheet, column, sphere and the like, preferably sphere. Shaping may be performed as is known in the art.
In the above method, the cycloalkane in the cycloalkane-containing material is cyclopropane, and the cyclopropane can be directly contacted with the 5A molecular sieve, or can be contacted with the 5A molecular sieve in the form of a mixed gas of cyclopropane and inert gas.
In the above method, it is preferable that a mixed gas of cyclopropane and an inert gas, the concentration of which is not more than 60% by volume, preferably not more than 50% by volume, more preferably 10 to 40% by volume, still more preferably 20 to 30% by volume, is contacted with the 5A molecular sieve.
In the above method, the contact mode is that the 5A molecular sieve is placed in the material containing cycloparaffin to make the material containing cycloparaffin fully contact, the typical placing time is 0.1-2h, preferably 0.5-1h, then the temperature is quickly raised to 350-650 ℃, preferably 400-500 ℃ under the sealing condition, the typical constant time is 0.5-1.5h, and the temperature raising speed is 50-100 ℃/min, preferably 60-80 ℃/min. The specific operation is that the 5A molecular sieve is placed in a reaction kettle or a tubular reactor, the material containing cycloalkane is introduced to replace the air in the reaction kettle or the tubular reactor, and the temperature rising treatment is carried out after the sealing placement.
In the above method, the hydrothermal treatment condition is that the hydrothermal treatment is carried out with steam at 150 to 600 ℃, preferably 300 to 450 ℃ for 0.5 to 20 hours, preferably 1 to 10 hours.
In the above method, the water vapor used in the hydrothermal treatment may be 50% -100% water vapor, and may contain nitrogen, helium, and other components. The hydrothermal treatment can be carried out under one temperature condition or can be carried out in multiple stages under different temperature conditions, and the mode of high-temperature treatment and low-temperature treatment is preferred, wherein the temperature difference between the high-temperature treatment and the low-temperature treatment is 100-200 ℃. The preferred mode of operation is, for example, first a hydrothermal treatment at 250-500℃for 0.5-10 hours, then a hydrothermal treatment at 150-200℃for a further 0.5-10 hours. The pressure (absolute pressure) of the hydrothermal treatment is generally 0.01-3 MPa, and the adsorption capacity of the modified 5A molecular sieve can be further improved by adopting a sectional treatment mode of firstly increasing and secondly decreasing.
In the method, the volume content of ammonia in the ammonia vapor mixed atmosphere is 10-45%, the treatment temperature is 120-150 ℃ and the treatment time is 0.5-6h.
In the above method, the drying temperature in the step (3) or the step (4) may be 50 to 200 ℃, preferably 60 to 150 ℃, more preferably 80 to 120 ℃; the drying time is 1 to 24 hours, preferably 4 to 8 hours; the drying can be vacuum drying, drying under the protection of inert gas or drying under the air atmosphere; the roasting temperature is 200-800 ℃, preferably 400-600 ℃; the roasting time is 1 to 24 hours, preferably 4 to 8 hours; the calcination is performed in an air atmosphere or an oxygen atmosphere.
The modified 5A molecular sieve prepared by the method. The modified 5A molecular sieve is used as an adsorbent for adsorption separation of naphtha, and the specific separation process is as follows: naphtha is used as raw material, the bed temperature is 100-300 ℃, the bed pressure is 0.1-2.5 Mpa, and the mass airspeed is 0.2-4 h -1 The feedstock is contacted with an adsorbent, wherein the adsorbent particles used are 1.6mm to 2.3mm.
The method comprises the steps of carbonizing the outer surface of the 5A molecular sieve, stabilizing the pore opening on the outer surface of the 5A molecular sieve, performing hydrothermal treatment on the 5A molecular sieve, reaming and modifying the inner pores of the 5A molecular sieve, and performing proper reaming on the pore opening on the surface of the 5A molecular sieve, wherein the modified 5A molecular sieve has better adsorption selectivity on low-octane components such as normal alkane, methylpentane, monomethyl hexane and the like as an adsorbent.
Detailed Description
The technical aspects and effects obtained by the method of the present invention will be further described with reference to examples and comparative examples, but the following examples do not limit the method of the present invention.
Example 1
(1) Weighing a proper amount of spherical 5A molecular sieve ((commercial commodity, main performance is as follows: specific surface: 680 cm) 2 Per g pore volume: 0.18cm 3 /g, average pore size: 1.7nm, particle diameter: 1.6 mm-2.3 mm), placing a 5A molecular sieve in a tube furnace, introducing a mixed gas of cyclopropane and inert gas to completely replace air in the tube furnace, sealing, wherein the concentration of the cyclopropane in the mixed gas is 20 vol%, placing for 0.5h after sealing, then quickly heating to 400 ℃ under a sealing condition for 0.5h, cooling to normal temperature, and heating up at a speed of 60 ℃/min;
(2) Carrying out hydrothermal treatment on the sample obtained in the step (1), wherein the hydrothermal treatment condition is that 100v% steam is used for carrying out hydrothermal treatment for 5 hours at the temperature of 450 ℃, and the pressure (absolute pressure) of the hydrothermal treatment is 3MPa;
(3) Carrying out vacuum drying at 120 ℃ for 4 hours after the hydrothermal treatment, and roasting at 600 ℃ in an air atmosphere for 4 hours;
(4) The material treated in the step (3) is treated in an ammonia gas and water vapor mixed atmosphere; the volume content of ammonia in the ammonia vapor mixed atmosphere is 20%, the treatment temperature is 150 ℃, the treatment time is 5 hours, the modified molecular sieve is prepared by vacuum drying at 120 ℃ for 4 hours after the treatment and roasting at 600 ℃ in air atmosphere for 4 hours.
Dynamic evaluation of adsorbent on fixed bed adsorption unit: the laboratory raw material is naphtha, wherein the total weight content of C4 to C8 normal paraffins is 21.25 percent, and the monomethyl iso-alkane isThe content of the alkane is as follows; the experimental conditions are that the temperature of the adsorbent bed is 235 ℃, the pressure of the bed is 0.4Mpa, the filling content of the adsorbent is 25g, the height of the bed is 25cm, and the mass airspeed is 1.5h -1 Under the condition that the raw materials are contacted with an adsorbent, the adsorption quantity (the main components are n-alkane and monomethyl isoparaffin) of the n-alkane in naphtha at the penetration point and the content of the n-alkane and the monomethyl isoparaffin in the naphtha after adsorption are measured by taking the content of the n-alkane in the raffinate oil of 1wt% as the penetration point, and the results are shown in Table 1; stopping feeding nitrogen to purge and desorb, and feeding and adsorbing after the desorption.
Example 2
(1) Weighing a proper amount of spherical 5A molecular sieve ((commercial commodity, main performance is as follows: specific surface: 680 cm) 2 Per g pore volume: 0.18cm 3 /g, average pore size: 1.7nm, particle diameter: 1.6 mm-2.3 mm), placing a 5A molecular sieve in a tube furnace, introducing a mixed gas of cyclopropane and inert gas to completely replace air in the tube furnace, sealing, wherein the concentration of the cyclopropane in the mixed gas is 30 vol%, placing for 1h after sealing, and then quickly heating to 500 ℃ under a sealing condition for 1.5h, and then cooling to normal temperature, wherein the heating rate is 80 ℃/min;
(2) Carrying out hydrothermal treatment on the sample obtained in the step (1), wherein the hydrothermal treatment condition is that 100v% steam is used for carrying out hydrothermal treatment for 8 hours at the temperature of 300 ℃, and the pressure (absolute pressure) of the hydrothermal treatment is 3MPa;
(3) After the hydrothermal treatment, carrying out vacuum drying at 80 ℃ for 8 hours, and roasting at 400 ℃ for 8 hours in an air atmosphere;
(4) The material treated in the step (3) is treated in an ammonia gas and water vapor mixed atmosphere; the volume content of ammonia in the ammonia gas and water vapor mixed atmosphere is 40%, the treatment temperature is 120 ℃, the treatment time is 2 hours, the modified 5A molecular sieve is prepared by carrying out vacuum drying for 4 hours at 120 ℃ and roasting for 4 hours in an air atmosphere at 600 ℃ after the hydrothermal treatment.
Dynamic evaluation of adsorbent on fixed bed adsorption unit: the laboratory raw material is naphtha, wherein the total weight content of C4 to C8 normal paraffins is 21.25 percent, and the content of monomethyl isoparaffin is; the experimental condition is that the temperature of the adsorbent bed layer is 235 ℃, the pressure of the bed layer is 0.4Mpa, and the adsorbent is adsorbedThe filling content of the catalyst is 25g, the height of the bed layer is 25cm, and the mass airspeed is 1.5h -1 Under the condition that the raw materials are contacted with an adsorbent, the adsorption quantity (the main components are n-alkane and monomethyl isoparaffin) of the n-alkane in naphtha at the penetration point and the content of the n-alkane and the monomethyl isoparaffin in the naphtha after adsorption are measured by taking the content of the n-alkane in the raffinate oil of 1wt% as the penetration point, and the results are shown in Table 1; stopping feeding nitrogen to purge and desorb, and feeding and adsorbing after the desorption.
Example 3
(1) Weighing a proper amount of spherical 5A molecular sieve ((commercial commodity, main performance is as follows: specific surface: 680 cm) 2 Per g pore volume: 0.18cm 3 /g, average pore size: 1.7nm, particle diameter: 1.6 mm-2.3 mm), placing a 5A molecular sieve in a tube furnace, introducing a mixed gas of cyclopropane and inert gas to completely replace air in the tube furnace, sealing, wherein the concentration of the cyclopropane in the mixed gas is 50 vol%, placing for 1h after sealing, and then quickly heating to 550 ℃ under a sealing condition for constant 0.5h, and then cooling to normal temperature, wherein the heating rate is 70 ℃/min;
(2) Carrying out hydrothermal treatment on the sample obtained in the step (1), wherein the hydrothermal treatment condition is that 80v% of water vapor and 20v% of nitrogen gas are used for carrying out hydrothermal treatment for 8 hours at 400 ℃, and the pressure (absolute pressure) of the hydrothermal treatment is 2.5MPa;
(3) After the hydrothermal treatment, vacuum drying is carried out for 8 hours at 120 ℃, and roasting is carried out for 8 hours in an air atmosphere at 500 ℃;
(4) The material treated in the step (3) is treated in an ammonia gas and water vapor mixed atmosphere; the volume content of ammonia in the ammonia gas and water vapor mixed atmosphere is 30%, the treatment temperature is 135 ℃, the treatment time is 4 hours, the modified 5A molecular sieve is prepared by carrying out vacuum drying at 120 ℃ for 4 hours after hydrothermal treatment and roasting at 600 ℃ for 4 hours in an air atmosphere.
Dynamic evaluation of adsorbent on fixed bed adsorption unit: the laboratory raw material is naphtha, wherein the total weight content of C4 to C8 normal paraffins is 21.25 percent, and the content of monomethyl isoparaffin is 11.21 percent; the experimental conditions are that the temperature of the adsorbent bed is 235 ℃, the pressure of the bed is 0.4Mpa, the filling content of the adsorbent is 25g, the height of the bed is 25cm, and the mass airspeed is 1.5h -1 Under the condition that the raw materials are contacted with an adsorbent, the adsorption quantity (the main components are n-alkane and monomethyl isoparaffin) of the n-alkane in naphtha at the penetration point and the content of the n-alkane and the monomethyl isoparaffin in the naphtha after adsorption are measured by taking the content of the n-alkane in the raffinate oil of 1wt% as the penetration point, and the results are shown in Table 1; stopping feeding nitrogen to purge and desorb, and feeding and adsorbing after the desorption.
Example 4
(1) Weighing a proper amount of spherical 5A molecular sieve ((commercial commodity, main performance is as follows: specific surface: 680 cm) 2 Per g pore volume: 0.18cm 3 /g, average pore size: 1.7nm, particle diameter: 1.6 mm-2.3 mm), placing a 5A molecular sieve in a tube furnace, introducing a mixed gas of cyclopropane and inert gas to completely replace air in the tube furnace, sealing, wherein the concentration of the cyclopropane in the mixed gas is 40 vol%, placing for 1h after sealing, and then quickly heating to 500 ℃ under a sealing condition for constant 0.5h, and then cooling to normal temperature, wherein the heating rate is 65 ℃/min;
(2) Carrying out hydrothermal treatment on the sample obtained in the step (1), wherein the hydrothermal treatment condition is that 80v% of water vapor and 20v% of nitrogen gas are used for carrying out hydrothermal treatment for 8 hours at the temperature of 450 ℃, and the pressure (absolute pressure) of the hydrothermal treatment is 2.5MPa;
(3) After the hydrothermal treatment, vacuum drying is carried out for 8 hours at 120 ℃, and roasting is carried out for 8 hours in an air atmosphere at 500 ℃;
(4) The material treated in the step (3) is treated in an ammonia gas and water vapor mixed atmosphere; the volume content of ammonia in the ammonia gas and water vapor mixed atmosphere is 30%, the treatment temperature is 135 ℃, the treatment time is 4 hours, the modified 5A molecular sieve is prepared by carrying out vacuum drying at 120 ℃ for 4 hours after hydrothermal treatment and roasting at 500 ℃ in air atmosphere for 4 hours.
Dynamic evaluation of adsorbent on fixed bed adsorption unit: the laboratory raw material is naphtha, wherein the total weight content of C4 to C8 normal paraffins is 21.25 percent, and the content of monomethyl isoparaffin is 11.21 percent; the experimental conditions are that the temperature of the adsorbent bed is 235 ℃, the pressure of the bed is 0.4Mpa, the filling content of the adsorbent is 25g, the height of the bed is 25cm, and the mass airspeed is 1.5h -1 Under the condition that the raw material is contacted with the adsorbent to ensure that the normal alkane content in the raffinate oil is 1The weight percent is a penetration point, the adsorption quantity (the main components are normal paraffins and monomethyl isoparaffin) of the normal paraffins in the naphtha at the penetration point and the content of the normal paraffins and the monomethyl isoparaffin in the naphtha after adsorption are measured, and the results are shown in Table 1; stopping feeding nitrogen to purge and desorb, and feeding and adsorbing after the desorption.
Example 5
(1) Weighing a proper amount of spherical 5A molecular sieve ((commercial commodity, main performance is as follows: specific surface: 680 cm) 2 Per g pore volume: 0.18cm 3 /g, average pore size: 1.7nm, particle diameter: 1.6 mm-2.3 mm), placing a 5A molecular sieve in a tube furnace, introducing a mixed gas of cyclopropane and inert gas to completely replace air in the tube furnace, sealing, wherein the concentration of the cyclopropane in the mixed gas is 25 vol%, placing for 1.5h after sealing, then quickly heating to 500 ℃ under a sealing condition for 0.5h, cooling to normal temperature, and heating up to 65 ℃/min;
(2) Carrying out hydrothermal treatment on the sample obtained in the step (1), wherein the hydrothermal treatment condition is that 90v% water vapor and 10v% nitrogen gas mixture are used for carrying out hydrothermal treatment for 8 hours at the temperature of 450 ℃, and the pressure (absolute pressure) of the hydrothermal treatment is 2.5MPa;
(3) After the hydrothermal treatment, vacuum drying is carried out for 8 hours at 120 ℃, and roasting is carried out for 8 hours in an air atmosphere at 500 ℃;
(4) The material treated in the step (3) is treated in an ammonia gas and water vapor mixed atmosphere; the volume content of ammonia in the ammonia gas and water vapor mixed atmosphere is 30%, the treatment temperature is 135 ℃, the treatment time is 4 hours, the modified 5A molecular sieve is prepared by carrying out vacuum drying at 120 ℃ for 4 hours after hydrothermal treatment and roasting at 500 ℃ in air atmosphere for 4 hours.
Dynamic evaluation of adsorbent on fixed bed adsorption unit: the laboratory raw material is naphtha, wherein the total weight content of C4 to C8 normal paraffins is 21.25 percent, and the content of monomethyl isoparaffin is 11.21 percent; the experimental conditions are that the temperature of the adsorbent bed is 235 ℃, the pressure of the bed is 0.4Mpa, the filling content of the adsorbent is 25g, the height of the bed is 25cm, and the mass airspeed is 1.5h -1 Under the condition that the raw material is contacted with an adsorbent, the adsorption quantity of normal paraffins in naphtha at the breakthrough point is measured by taking the content of normal paraffins in raffinate oil of 1wt% as the breakthrough point(the main components are normal paraffins and monomethyl isoparaffins) and the content of the normal paraffins and the monomethyl isoparaffins in the naphtha after adsorption, and the results are shown in Table 1; stopping feeding nitrogen to purge and desorb, and feeding and adsorbing after the desorption.
Example 6
(1) Weighing a proper amount of spherical 5A molecular sieve ((commercial commodity, main performance is as follows: specific surface: 680 cm) 2 Per g pore volume: 0.18cm 3 /g, average pore size: 1.7nm, particle diameter: 1.6 mm-2.3 mm), placing a 5A molecular sieve in a tube furnace, introducing a mixed gas of cyclopropane and inert gas to completely replace air in the tube furnace, sealing, wherein the concentration of the cyclopropane in the mixed gas is 55 vol%, placing for 0.8h after sealing, then quickly heating to 480 ℃ under a sealing condition for 0.8h, cooling to normal temperature, and heating up at a speed of 55 ℃/min;
(2) Carrying out hydrothermal treatment on the sample obtained in the step (1), wherein the hydrothermal treatment condition is that 80v% of water vapor and 20v% of nitrogen gas are used for carrying out hydrothermal treatment for 8 hours at the temperature of 450 ℃, and the pressure (absolute pressure) of the hydrothermal treatment is 2.5MPa;
(3) After the hydrothermal treatment, vacuum drying is carried out for 8 hours at 120 ℃, and roasting is carried out for 8 hours in an air atmosphere at 500 ℃;
(4) The material treated in the step (3) is treated in an ammonia gas and water vapor mixed atmosphere; the volume content of ammonia in the ammonia gas and water vapor mixed atmosphere is 30%, the treatment temperature is 135 ℃, the treatment time is 4 hours, the modified 5A molecular sieve is prepared by carrying out vacuum drying at 120 ℃ for 4 hours after hydrothermal treatment and roasting at 500 ℃ in air atmosphere for 4 hours.
Dynamic evaluation of adsorbent on fixed bed adsorption unit: the laboratory raw material is naphtha, wherein the total weight content of C4 to C8 normal paraffins is 21.25 percent, and the content of monomethyl isoparaffin is 11.21 percent; the experimental conditions are that the temperature of the adsorbent bed is 235 ℃, the pressure of the bed is 0.4Mpa, the filling content of the adsorbent is 25g, the height of the bed is 25cm, and the mass airspeed is 1.5h -1 Under the condition that the raw material is contacted with an adsorbent, the adsorption quantity (the main components are n-alkane and monomethyl isoparaffin) of the n-alkane in naphtha at the penetration point and the adsorbed stone are measured by taking the n-alkane content of 1wt% in raffinate oil as the penetration pointThe content of normal alkane and monomethyl isoparaffin in the brain oil is shown in Table 1; stopping feeding nitrogen to purge and desorb, and feeding and adsorbing after the desorption.
Example 7
(1) Weighing a proper amount of spherical 5A molecular sieve ((commercial commodity, main performance is as follows: specific surface: 680 cm) 2 Per g pore volume: 0.18cm 3 /g, average pore size: 1.7nm, particle diameter: 1.6 mm-2.3 mm), placing a 5A molecular sieve in a tube furnace, introducing a mixed gas of cyclopropane and inert gas to completely replace air in the tube furnace, sealing, wherein the concentration of the cyclopropane in the mixed gas is 20 vol%, placing for 0.5h after sealing, then quickly heating to 400 ℃ under a sealing condition for 0.5h, cooling to normal temperature, and heating up at a speed of 60 ℃/min;
(2) Carrying out hydrothermal treatment on the sample obtained in the step (1), wherein the hydrothermal treatment condition is that firstly 100v% steam is used for carrying out hydrothermal treatment for 3 hours at 300 ℃, the pressure of the hydrothermal treatment is (absolute pressure) 3MPa, then 100v% steam is used for carrying out hydrothermal treatment for 4 hours at 180 ℃, and the pressure of the hydrothermal treatment is (absolute pressure) 1.5MPa;
(3) After the hydrothermal treatment, vacuum drying is carried out for 8 hours at 120 ℃, and roasting is carried out for 8 hours in an air atmosphere at 500 ℃;
(4) The material treated in the step (3) is treated in an ammonia gas and water vapor mixed atmosphere; the volume content of ammonia in the ammonia gas and water vapor mixed atmosphere is 30%, the treatment temperature is 135 ℃, the treatment time is 4 hours, the modified 5A molecular sieve is prepared by carrying out vacuum drying at 120 ℃ for 4 hours after hydrothermal treatment and roasting at 500 ℃ in air atmosphere for 4 hours.
Dynamic evaluation of adsorbent on fixed bed adsorption unit: the laboratory raw material is naphtha, wherein the total weight content of C4 to C8 normal paraffins is 21.25 percent, and the content of monomethyl isoparaffin is 11.21 percent; the experimental conditions are that the temperature of the adsorbent bed is 235 ℃, the pressure of the bed is 0.4Mpa, the filling content of the adsorbent is 25g, the height of the bed is 25cm, and the mass airspeed is 1.5h -1 Under the condition that the raw material is contacted with an adsorbent, the adsorption quantity of normal paraffins in naphtha at the penetration point is measured by taking the content of normal paraffins in raffinate oil of 1wt% as the penetration point (the main components are normal paraffins and monomethyl isoparaffin)) And the content of normal paraffins and monomethyl isoparaffin in the naphtha after adsorption, and the results are shown in Table 1; stopping feeding nitrogen to purge and desorb, and feeding and adsorbing after the desorption.
Comparative example 1 [ same as example 1 except that there is no step (4) ]
(1) Weighing a proper amount of spherical 5A molecular sieve ((commercial commodity, main performance is as follows: specific surface: 680 cm) 2 Per g pore volume: 0.18cm 3 /g, average pore size: 1.7nm, particle diameter: 1.6 mm-2.3 mm), placing a 5A molecular sieve in a tube furnace, introducing a mixed gas of cyclopropane and inert gas to completely replace air in the tube furnace, sealing, wherein the concentration of the cyclopropane in the mixed gas is 20 vol%, placing for 0.5h after sealing, then quickly heating to 400 ℃ under a sealing condition for 0.5h, cooling to normal temperature, and heating up at a speed of 60 ℃/min;
(2) Carrying out hydrothermal treatment on the sample obtained in the step (1), wherein the hydrothermal treatment condition is that 100v% steam is used for carrying out hydrothermal treatment for 5 hours at the temperature of 450 ℃, and the pressure (absolute pressure) of the hydrothermal treatment is 3MPa;
(3) And (3) carrying out vacuum drying at 120 ℃ for 4 hours after the hydrothermal treatment, and roasting at 600 ℃ in an air atmosphere for 4 hours to obtain the modified molecular sieve.
Dynamic evaluation of adsorbent on fixed bed adsorption unit: the laboratory raw material is naphtha, wherein the total weight content of C4 to C8 normal paraffins is 21.25 percent, and the content of monomethyl isoparaffin is 11.21 percent; the experimental conditions are that the temperature of the adsorbent bed is 235 ℃, the pressure of the bed is 0.4Mpa, the filling content of the adsorbent is 25g, the height of the bed is 25cm, and the mass airspeed is 1.5h -1 Under the condition that the raw materials are contacted with an adsorbent, the adsorption quantity (the main components are n-alkane and monomethyl isoparaffin) of the n-alkane in naphtha at the penetration point and the content of the n-alkane and the monomethyl isoparaffin in the naphtha after adsorption are measured by taking the content of the n-alkane in the raffinate oil of 1wt% as the penetration point, and the results are shown in Table 1; stopping feeding nitrogen to purge and desorb, and feeding and adsorbing after the desorption.
Comparative example 2
The 5A molecular sieve is directly used as an adsorbent. Dynamic evaluation of adsorbent on fixed bed adsorption unit: the laboratory feedstock is naphtha, whereinThe total weight content of C4 to C8 normal paraffins is 21.25 percent, and the content of monomethyl isoparaffin is 11.21 percent; the experimental conditions are that the temperature of the adsorbent bed is 235 ℃, the pressure of the bed is 0.4Mpa, the filling content of the adsorbent is 25g, the height of the bed is 25cm, and the mass airspeed is 1.5h -1 Under the condition that the raw materials are contacted with an adsorbent, the adsorption quantity (the main components are n-alkane and monomethyl isoparaffin) of the n-alkane in naphtha at the penetration point and the content of the n-alkane and the monomethyl isoparaffin in the naphtha after adsorption are measured by taking the content of the n-alkane in the raffinate oil of 1wt% as the penetration point, and the results are shown in Table 1; stopping feeding nitrogen to purge and desorb, and feeding and adsorbing after the desorption.
TABLE 1
Claims (20)
1. A preparation method of a modified 5A molecular sieve is characterized by comprising the following steps: the method comprises the following steps:
(1) Fully contacting a material containing cycloparaffin with a 5A molecular sieve, and quickly heating to carbonize the 5A molecular sieve;
(2) Carrying out hydrothermal treatment on the material obtained in the step (1);
(3) Drying and roasting the material treated in the step (2);
(4) Treating the treated material in the step (3) in an ammonia gas and steam mixed atmosphere, and drying and roasting the treated material to obtain a modified 5A molecular sieve;
the cycloalkane in the cycloalkane-containing material is cyclopropane.
2. The method according to claim 1, characterized in that: the 5A molecular sieve is an existing commercial product or is prepared according to methods well known to those skilled in the art.
3. The method according to claim 2, characterized in that: the 5A molecular sieve is one of strip, sheet, column or sphere.
4. The method according to claim 1, characterized in that: the cyclopropane is directly contacted with the 5A molecular sieve or the mixed gas of the cyclopropane and inert gas is contacted with the 5A molecular sieve.
5. The method according to claim 4, wherein: a mixture of cyclopropane and an inert gas, the mixture having a concentration of cyclopropane of not more than 60% by volume, is contacted with a 5A molecular sieve.
6. The method according to claim 5, wherein: the concentration of cyclopropane in the mixed gas is 10-40% by volume.
7. The method according to claim 1, characterized in that: the contact mode is that the 5A molecular sieve is placed in the material containing cycloparaffin to make the material containing cycloparaffin fully contact, the placing time is 0.1-2h, then the temperature is quickly raised to 350-650 ℃ under the sealing condition, the constant time is 0.5-1.5h, and the heating speed is 50-100 ℃/min.
8. The method according to claim 7, wherein: the standing time is 0.5-1h, and then the temperature is quickly raised to 400-500 ℃ under the sealing condition, and the temperature raising speed is 60-80 ℃/min.
9. The method according to claim 7, wherein: placing the 5A molecular sieve in a reaction kettle or a tubular reactor, introducing a material containing cycloalkanes to replace air in the reaction kettle or the tubular reactor, sealing and placing, and then heating.
10. The method according to claim 1, characterized in that: the hydrothermal treatment condition is that steam is used for carrying out hydrothermal treatment for 0.5-20 h at the temperature of 150-600 ℃.
11. The method according to claim 10, wherein: the hydrothermal treatment condition is that the hydrothermal treatment is carried out by using steam for 1-10 hours under the condition of 300-450 ℃.
12. The method according to claim 10, wherein: the water vapor used in the hydrothermal treatment is 50% -100%.
13. The method according to claim 10, wherein: the hydrothermal treatment adopts a mode of high-temperature treatment and then low-temperature treatment, and the temperature difference between the high-temperature treatment and the low-temperature treatment is 100-200 ℃.
14. The method according to claim 13, wherein: firstly, carrying out hydrothermal treatment for 0.5-10 h at 250-500 ℃, and then carrying out hydrothermal treatment for 0.5-10 h at 150-200 ℃.
15. The method according to claim 1, characterized in that: the volume content of ammonia in the ammonia vapor mixed atmosphere is 10-45%, the treatment temperature is 120-150 ℃ and the treatment time is 0.5-6h.
16. The method according to claim 1, characterized in that: the drying temperature in the step (3) or the step (4) is 50-200 ℃; the drying time is 1-24 hours; the roasting temperature is 200-800 ℃; the roasting time is 1-24 hours.
17. The method according to claim 16, wherein: the drying temperature is 60-150 ℃; the drying time is 4-8 hours; the roasting temperature is 400-600 ℃; the roasting time is 4-8 hours.
18. A modified 5A molecular sieve, characterized by: prepared by any one of methods 1 to 17.
19. The modified 5A molecular sieve of claim 18 applied as an adsorbent for adsorptive separation of naphtha.
20. The use according to claim 19, characterized in that: the specific separation process is as follows: naphtha is used as raw material, the bed temperature is 100-300 ℃, the bed pressure is 0.1-2.5 Mpa, and the mass airspeed is 0.2-4 h -1 The feedstock is contacted with the adsorbent.
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| 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 |
| CN107694562A (en) * | 2016-08-08 | 2018-02-16 | 中国科学院大连化学物理研究所 | A kind of integer catalyzer and its preparation and application |
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