CN114505094B - Modification method of ZSM-5 molecular sieve and ZSM-5 molecular sieve catalyst - Google Patents
Modification method of ZSM-5 molecular sieve and ZSM-5 molecular sieve catalyst 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 185
- 239000002808 molecular sieve Substances 0.000 title claims abstract description 184
- 239000003054 catalyst Substances 0.000 title claims abstract description 39
- 238000002715 modification method Methods 0.000 title claims abstract description 26
- 239000002253 acid Substances 0.000 claims abstract description 88
- 238000006243 chemical reaction Methods 0.000 claims abstract description 49
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 39
- 239000007788 liquid Substances 0.000 claims abstract description 36
- 239000008367 deionised water Substances 0.000 claims abstract description 32
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 32
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 27
- 238000000034 method Methods 0.000 claims abstract description 20
- 238000010438 heat treatment Methods 0.000 claims abstract description 19
- 238000001035 drying Methods 0.000 claims abstract description 8
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 25
- 238000005406 washing Methods 0.000 claims description 22
- 229910052751 metal Inorganic materials 0.000 claims description 19
- 239000002184 metal Substances 0.000 claims description 19
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 9
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 8
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 6
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 5
- 229910017604 nitric acid Inorganic materials 0.000 claims description 5
- 230000035484 reaction time Effects 0.000 claims description 5
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 4
- 230000005484 gravity Effects 0.000 claims 2
- 239000011148 porous material Substances 0.000 abstract description 17
- 230000008901 benefit Effects 0.000 abstract description 11
- 230000008569 process Effects 0.000 abstract description 7
- 238000009826 distribution Methods 0.000 abstract description 6
- 238000005265 energy consumption Methods 0.000 abstract description 4
- 230000000052 comparative effect Effects 0.000 description 22
- 150000001335 aliphatic alkanes Chemical class 0.000 description 15
- 238000006317 isomerization reaction Methods 0.000 description 14
- 230000000694 effects Effects 0.000 description 12
- 239000000843 powder Substances 0.000 description 12
- 230000004048 modification Effects 0.000 description 10
- 238000012986 modification Methods 0.000 description 10
- TVMXDCGIABBOFY-UHFFFAOYSA-N octane Chemical compound CCCCCCCC TVMXDCGIABBOFY-UHFFFAOYSA-N 0.000 description 10
- QGZKDVFQNNGYKY-UHFFFAOYSA-O ammonium group Chemical group [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- 238000002360 preparation method Methods 0.000 description 7
- 238000005086 pumping Methods 0.000 description 7
- 239000012065 filter cake Substances 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- 238000003756 stirring Methods 0.000 description 6
- 238000010306 acid treatment Methods 0.000 description 5
- 230000003197 catalytic effect Effects 0.000 description 5
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 4
- 238000012216 screening Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 description 3
- 238000012512 characterization method Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 239000000706 filtrate Substances 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 238000010335 hydrothermal treatment Methods 0.000 description 3
- 230000007935 neutral effect Effects 0.000 description 3
- 229910000510 noble metal Inorganic materials 0.000 description 3
- 239000003755 preservative agent Substances 0.000 description 3
- 230000002335 preservative effect Effects 0.000 description 3
- 238000007789 sealing Methods 0.000 description 3
- 238000005303 weighing Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 239000002841 Lewis acid Substances 0.000 description 2
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 description 2
- 239000006004 Quartz sand Substances 0.000 description 2
- 241000219782 Sesbania Species 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- -1 amine cations Chemical class 0.000 description 2
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 2
- 235000019270 ammonium chloride Nutrition 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 150000001768 cations Chemical class 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 150000007517 lewis acids Chemical class 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000012856 packing Methods 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229920000742 Cotton Polymers 0.000 description 1
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 description 1
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 1
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 description 1
- 229910021536 Zeolite Inorganic materials 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- HQABUPZFAYXKJW-UHFFFAOYSA-N butan-1-amine Chemical compound CCCCN HQABUPZFAYXKJW-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 125000005842 heteroatom Chemical group 0.000 description 1
- 238000005470 impregnation Methods 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 239000000543 intermediate Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 description 1
- 238000002119 pyrolysis Fourier transform infrared spectroscopy Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- BGQMOFGZRJUORO-UHFFFAOYSA-M tetrapropylammonium bromide Chemical compound [Br-].CCC[N+](CCC)(CCC)CCC BGQMOFGZRJUORO-UHFFFAOYSA-M 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 229910001845 yogo sapphire Inorganic materials 0.000 description 1
- 239000010457 zeolite Substances 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
- B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
- B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
- B01J29/42—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively containing iron group metals, noble metals or copper
- B01J29/44—Noble metals
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
- B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
- B01J29/48—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively containing arsenic, antimony, bismuth, vanadium, niobium tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
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- B01J35/615—
-
- B01J35/633—
-
- 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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/02—Impregnation, coating or precipitation
- B01J37/0201—Impregnation
- B01J37/0207—Pretreatment of the support
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
- C07C5/22—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by isomerisation
- C07C5/27—Rearrangement of carbon atoms in the hydrocarbon skeleton
- C07C5/2767—Changing the number of side-chains
- C07C5/277—Catalytic processes
- C07C5/2775—Catalytic processes with crystalline alumino-silicates, e.g. molecular sieves
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
- B01J2229/10—After treatment, characterised by the effect to be obtained
- B01J2229/18—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
- B01J2229/30—After treatment, characterised by the means used
- B01J2229/37—Acid treatment
Abstract
The invention discloses a modification method of a ZSM-5 molecular sieve and a ZSM-5 molecular sieve catalyst, belonging to the field of catalysts. The modification method of the ZSM-5 molecular sieve comprises the following steps: providing a ZSM-5 molecular sieve without template removal; putting ZSM-5 molecular sieve without template removal agent into a super-gravity impact flow-rotating packed bed, heating to a reaction temperature, and adding acid liquor into the super-gravity impact flow-rotating packed bed through a liquid feed pipe; deionized water is continuously added into the supergravity impinging stream-rotating packed bed through the liquid feed pipe, the ZSM-5 molecular sieve modified by the acid liquor is washed, and then drying treatment is carried out, so that the modified ZSM-5 molecular sieve is obtained. The method can obtain the modified ZSM-5 molecular sieve with reasonable acid value distribution and a cascade pore channel structure, and has the advantages of simple process, low energy consumption, low pollution discharge and low cost.
Description
Technical Field
The invention relates to the field of catalysts, in particular to a modification method of a ZSM-5 molecular sieve and a ZSM-5 molecular sieve catalyst.
Background
ZSM-5 molecular sieve is a novel zeolite molecular sieve containing organic amine cations, and the chemical composition of the molecular sieve can be expressed by the mole ratio of oxides: 0.9 + -0.2M 2/nO:Al2O3:5---100SiO2:ZH2 O, wherein M is a cation (alkali metal sodium ion and organic amine ion); n is the valence of the cation; z is from 0 to 40. The ZSM-5 molecular sieve contains two crossed pore channel systems: the unique micropore structures of the longitudinal straight-barrel-shaped pore channels and the transverse sine-shaped pore channels can provide excellent shape selectivity performance for the reaction, but on the other hand, the diffusion and mass transfer of reactants, intermediates and products with larger steric hindrance in the pore channels are limited, so that the pore channels of the molecular sieve are required to be regulated to optimize the pore channel structure of the molecular sieve. In addition, the ZSM-5 molecular sieve has stronger acidity and higher acid density, so that the corresponding catalyst has higher initial activity and is rapidly deactivated due to the rapid generation of carbon deposit, and the activity, the product selectivity and the service life of the catalyst are all important influences, so that the acidity of the ZSM-5 molecular sieve also needs to be properly adjusted to adapt to specific reactions.
Currently, modifications to ZSM-5 molecular sieves typically include hydrothermal treatment, acid-base modification, heteroatom modification, and the like. For example, the related art utilizes a hydrothermal-citric acid modification process to treat a ZSM-5 molecular sieve, the basic treatment process of which is as follows: the template removing agent comprises ammonium exchange, roasting, high-temperature hydrothermal treatment and citric acid treatment. Removing a template agent generated in the synthesis process of the ZSM-5 molecular sieve by roasting, and exchanging NaZSM-5 into HZSM-5 by twice ammonium exchange and roasting; then, the framework aluminum is partially removed through high-temperature hydrothermal treatment, so that the acidity of the molecular sieve is reduced, and the hole expanding effect is achieved, namely, the microporous ZSM-5 molecular sieve is modified into a stepped hole molecular sieve; finally, citric acid is used for treatment to remove non-framework aluminum in the framework. Finally, the modified ZSM-5 molecular sieve is obtained, the pore channels are more open due to the reduction of the acidity, and the acid strength distribution of the molecular sieve tends to be average.
In carrying out the invention, the inventors have found that there are at least the following problems in the prior art:
The modification method provided by the related technology has the advantages of complicated steps, overlarge energy consumption for repeated roasting, emission of pollutants such as ammonia, acid and the like, and poor environmental protection.
Disclosure of Invention
In view of the above, the present invention provides a modification method of ZSM-5 molecular sieve and ZSM-5 molecular sieve catalyst, which can solve the above technical problems.
Specifically, the method comprises the following technical scheme:
in one aspect, the embodiment of the invention provides a modification method of a ZSM-5 molecular sieve, wherein the modification method of the ZSM-5 molecular sieve comprises the following steps: providing a ZSM-5 molecular sieve without template removal;
Placing the ZSM-5 molecular sieve without the template agent in a supergravity impact flow-rotating packed bed, heating to a reaction temperature, and adding acid liquor into the supergravity impact flow-rotating packed bed through a liquid feed pipe for reaction;
And after the reaction is finished, deionized water is continuously added into the supergravity impinging stream-rotating packed bed through the liquid feed pipe, the ZSM-5 molecular sieve modified by the acid liquor is washed, and then the drying treatment is carried out, so that the modified ZSM-5 molecular sieve is obtained.
In some possible implementations, the non-template ZSM-5 molecular sieve has a silica to alumina ratio of from 30 to 60.
In some possible implementations, the rotational speed of the supergravity impinging stream-rotating packed bed is 800r/min to 2000r/min when the acid solution is used to react with the non-template ZSM-5 molecular sieve.
In some possible implementations, the acid solution is selected from at least one of nitric acid, hydrochloric acid, citric acid, phosphoric acid, and the mass space velocity of the acid solution is 0.5h -1～8.0h-1.
In some possible implementations, when the acid solution is used to react with the non-template ZSM-5 molecular sieve, the reaction temperature is 400-700 ℃, the temperature is raised to the reaction temperature at a rate of 5-20 ℃/min, and the reaction time is 3-8 hours.
In some possible implementations, the rotational speed of the supergravity impinging stream-rotating packed bed is 800r/min to 1000r/min when the acid-modified ZSM-5 molecular sieve is washed with deionized water.
In some possible implementations, when the ZSM-5 molecular sieve modified by the acid solution is washed by deionized water, the mass space velocity of the deionized water is 3.0h -1～6.0h-1, the washing temperature is 100-120 ℃, and the washing time is 10-30 min.
In another aspect, the present invention also provides a ZSM-5 molecular sieve catalyst, the ZSM-5 molecular sieve catalyst comprising: a modified ZSM-5 molecular sieve, and an active component supported on the modified ZSM-5 molecular sieve;
Wherein the modified ZSM-5 molecular sieve is prepared by the modification method of any one of the ZSM-5 molecular sieves.
In some possible implementations, the active component is selected from at least one of Pt metal, pd metal, rh metal, ni metal, W metal, mo metal.
In some possible implementations, the ZSM-5 molecular sieve catalyst has a particle size of from 20 mesh to 40 mesh.
The technical scheme provided by the embodiment of the invention has the beneficial effects that at least:
According to the modification method of the ZSM-5 molecular sieve, provided by the embodiment of the invention, the ZSM-5 molecular sieve without the template removing agent is placed in a supergravity impinging stream-rotating packed bed to react with acid liquor under the supergravity condition, so that the modified ZSM-5 molecular sieve with reasonable acid value distribution can be obtained, wherein the B/L value of the modified ZSM-5 molecular sieve is @ Acid value/Lewis acid value) is less than 0.2, and (weak acid value + medium strong acid value)/strong acid value is more than 3. The ZSM-5 molecular sieve modified by the acid liquor has a cascade pore channel structure, and the modified ZSM-5 molecular sieve is used as a carrier to load a catalyst active component and applied to catalyzing alkane hydroisomerization reaction, and has the advantages of high medium-temperature reaction activity, high alkane isomer selectivity, high dual-branched alkane isomer selectivity, high liquid yield and the like. The modification method of the ZSM-5 molecular sieve provided by the embodiment of the invention has the advantages of simple process, low energy consumption (reducing the acid liquid consumption), low pollution discharge (eliminating ammonia nitrogen discharge), low cost and the like on the premise of obtaining the modified ZSM-5 molecular sieve with better performance.
Detailed Description
In order to make the technical scheme and advantages of the present invention more apparent, the following detailed description of the embodiments of the present invention will be provided.
The embodiment of the invention provides a modification method of a ZSM-5 molecular sieve, which comprises the following steps:
And step 1, providing ZSM-5 molecular sieve without template removal.
And 2, placing the ZSM-5 molecular sieve without the template agent in a supergravity impact flow-rotating packed bed, heating to a reaction temperature, and adding acid liquor into the supergravity impact flow-rotating packed bed through a liquid feeding pipe for reaction. Wherein, the purpose of the acid liquor reaction is to convert the Na-type molecular sieve into an H-type molecular sieve.
And step 3, after the reaction is finished, deionized water is continuously added into the supergravity impinging stream-rotating packed bed through a liquid feed pipe, the ZSM-5 molecular sieve modified by the acid liquor is washed, and then drying treatment is carried out, so that the modified ZSM-5 molecular sieve is obtained. The purpose of the washing is to wash away the acid liquid remaining in the molecular sieve.
According to the modification method of the ZSM-5 molecular sieve, provided by the embodiment of the invention, the ZSM-5 molecular sieve without the template removing agent is placed in a supergravity impinging stream-rotating packed bed to react with acid liquor under the supergravity condition, so that the modified ZSM-5 molecular sieve with reasonable acid value distribution can be obtained, wherein the B/L value of the modified ZSM-5 molecular sieve is @Acid value/Lewis acid value) is less than 0.2, and (weak acid value + medium strong acid value)/strong acid value is more than 3. The ZSM-5 molecular sieve modified by the acid liquor has a cascade pore channel structure, and the modified ZSM-5 molecular sieve is used as a carrier to load a catalyst active component and applied to catalyzing alkane hydroisomerization reaction, and has the advantages of high medium-temperature reaction activity, high alkane isomer selectivity, high dual-branched alkane isomer selectivity, high liquid yield and the like. The modification method of the ZSM-5 molecular sieve provided by the embodiment of the invention has the advantages of simple process, low energy consumption (reducing the acid liquid consumption), low pollution discharge (eliminating ammonia nitrogen discharge), low cost and the like on the premise of obtaining the modified ZSM-5 molecular sieve with better performance.
The following are descriptions of the steps involved in the modification method of the ZSM-5 molecular sieve:
For step1, the ZSM-5 molecular sieve without template removal is provided, and the ZSM-5 molecular sieve without template removal is selected as a raw material in the embodiment of the invention, because the ZSM-5 molecular sieve is usually required to be synthesized by using template to guide the formation of molecular sieve structures, and is filled in molecular sieve pore channels, and the template is usually required to be removed after the molecular sieve is synthesized, so that smooth pore channels can be formed. The traditional preparation process is that firstly, a Na type molecular sieve containing a template agent is synthesized, then the template agent is removed through high-temperature roasting, and then the Na type molecular sieve is converted into an H type molecular sieve through acid exchange. The method provided by the embodiment of the invention can remove the template agent at the same time of acid exchange.
Wherein the template agent is guided to all organic amine formed by ZSM-5 molecular sieve framework, such as tetrapropylammonium bromide, n-butylamine, triethylamine, ethylenediamine and the like. For example, a ZSM-5 molecular sieve without a template refers to a NaZSM-5 molecular sieve.
In some possible implementations, the non-template ZSM-5 molecular sieve has a silica to alumina ratio of greater than 20, for example from 30 to 60.
In some possible implementations, the rotational speed of the supergravity impinging stream-rotating packed bed is 800r/min to 2000r/min, such as 800r/min, 1000r/min, 1200r/min, 1500r/min, 1700r/min, 2000r/min, etc., when reacting an acid solution with the non-template ZSM-5 molecular sieve.
The rotation speed of the super-gravity impact flow-rotary packed bed during acid liquor reaction is limited, because the super-gravity impact flow-rotary packed bed is impacted in opposite directions by two high-speed jet flows to form impact fog surfaces which enter the rotary packed bed along the radial direction, and the acid liquor fog surfaces are subjected to further enhanced mixing reaction in the rotary packed bed, so that the high-temperature acid treatment effect is improved through the rotation speed.
In some possible implementation manners, the acid solution used in the embodiment of the invention is at least one selected from nitric acid, hydrochloric acid, citric acid and phosphoric acid, and the mass airspeed of the acid solution is 0.5h -1～8.0h-1, so that the proper jet impact fog surface size, droplet particle size and the like are obtained, and further, a better high-temperature acid treatment effect is obtained.
In some possible implementations, when acid solution is used to react with the ZSM-5 molecular sieve without template, the reaction temperature is 400-700 ℃, the temperature is raised to the reaction temperature at a rate of 5-20 ℃ per minute, and the reaction time is 3-8 hours.
For example, the above reaction temperatures include, but are not limited to: 400 ℃, 450 ℃, 500 ℃, 550 ℃, 600 ℃, 650 ℃, 700 ℃, etc.
The rate of temperature increase includes, but is not limited to: 5 ℃/min, 10 ℃/min, 12 ℃/min, 15 ℃/min, 18 ℃/min, 20 ℃/min, etc.
Reaction times include, but are not limited to: 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, etc.
Under the operation parameters, the acid liquor is subjected to modification treatment on the ZSM-5 molecular sieve without the template removing agent, so that a better modification effect can be obtained, and the ZSM-5 molecular sieve modified by the acid liquor can obtain a desired cascade pore channel structure.
In some possible implementations, the rotational speed of the supergravity impinging stream-rotating packed bed is 800r/min to 1000r/min, such as 800r/min, 850r/min, 900r/min, 950r/min, 1000r/min, etc., when the acid modified ZSM-5 molecular sieve is washed with deionized water.
The above limitation is made to the rotation speed of the super-gravity impact flow-rotating packed bed during deionized water washing, because the super-gravity impact flow-rotating packed bed is impacted in opposite directions by two high-speed jet flows to form impact fog surfaces and enter the rotating packed bed along the radial direction, and the acid liquor fog surfaces are subjected to further enhanced mixing reaction in the rotating packed bed, so that the high-temperature acid treatment effect is improved through the rotation speed.
In some possible implementations, when the ZSM-5 molecular sieve modified by the acid solution is washed by deionized water, the mass space velocity of the deionized water is 3.0h -1～6.0h-1, the washing temperature is 100-120 ℃, and the washing time is 10-30 min.
For example, the above washing temperatures include, but are not limited to: 100 ℃, 110 ℃, 120 ℃, etc.
Washing times include, but are not limited to: 10 minutes, 15 minutes, 20 minutes, 25 minutes, etc.
The mass space velocity of deionized water includes, but is not limited to: 3.0h -1、4.0h-1、5.0h-1、6.0h-1, etc.
The deionized water is washed under the operation parameters, and a better washing effect can be obtained on the premise of not influencing the structure of the modified ZSM-5 molecular sieve.
On the other hand, the embodiment of the invention also provides a ZSM-5 molecular sieve catalyst, which comprises: modified ZSM-5 molecular sieve, and active component loaded on the modified ZSM-5 molecular sieve; wherein the modified ZSM-5 molecular sieve is prepared by the modification method of any one of the ZSM-5 molecular sieves.
The ZSM-5 molecular sieve catalyst provided by the embodiment of the invention uses the modified ZSM-5 molecular sieve prepared by the modification method of any one of the ZSM-5 molecular sieves, and when the modified ZSM-5 molecular sieve is used as a carrier loaded active component, the modified ZSM-5 molecular sieve can be used for catalyzing alkane hydroisomerization reaction, and the selectivity of high-octane products such as double-branched products can be effectively improved in the aspect of catalytic effect, so that the octane number of the isomerized products is improved. Even if the reaction is carried out at a low temperature of 200 ℃, a higher isomerization selectivity can be obtained.
In some possible implementations, the active component is selected from at least one of Pt metal, pd metal, rh metal, ni metal, W metal, mo metal.
The metal is selected, so that the ZSM-5 molecular sieve catalyst can be used for catalyzing alkane hydroisomerization reaction, and a good catalytic effect is obtained.
In some possible implementations, the ZSM-5 molecular sieve catalyst has a particle size of 20 meshes to 40 meshes, and the ZSM-5 molecular sieve catalyst with the mesh number has more proper specific surface area, which is further beneficial to improving the catalytic activity of the catalyst.
For the preparation of the above ZSM-5 molecular sieve catalyst, see the following steps:
The modified ZSM-5 molecular sieve obtained by the modification method provided by the embodiment of the invention is subjected to screening treatment, active components are loaded by adopting an isovolumetric impregnation method, naturally dried, and then baked to obtain the ZSM-5 molecular sieve catalyst.
The screening treatment modes include but are not limited to: tabletting screening or extrusion forming screening.
Further, the ZSM-5 molecular sieve catalyst provided by the embodiment of the invention further comprises: sesbania powder or alumina gel. In the preparation process, the modified ZSM-5 molecular sieve is doped with sesbania powder and alumina dry gel, extruded and molded, and then screened.
The catalytic performance of the modified ZSM-5 molecular sieve catalyst provided by the embodiment of the invention can be evaluated through alkane isomerization reaction, and the specific performance is as follows:
5g of modified ZSM-5 molecular sieve catalyst is placed in a catalyst bed layer of a 10mL miniature continuous flow fixed bed reactor, quartz sand is filled at the upper end, and an iron wire layer, a quartz cotton layer, porcelain balls and quartz sand are sequentially filled at the lower end from bottom to top.
N-octane is used as a model compound, and the reaction is carried out according to a certain reaction temperature, reaction pressure, hydrogen-oil volume ratio and mass airspeed.
For example, in carrying out the alkane isomerization reaction described above, the various operating parameters are as follows:
The reaction temperature T is 200 to 400 ℃, for example 200 to 250 to 300 to 350 to 400 ℃, etc.;
The reaction pressure P is 1MPa to 2MPa, for example, 1MPa, 1.2MPa, 1.5MPa, 1.7MPa, 2MPa and the like;
the hydrogen-oil volume ratio is 300-400, such as 300, 320, 340, 350, 370, 380, 400, etc.;
The mass space velocity WHSV is 1.0h -1～2.0h-1, for example 1.0h -1、1.2h-1、1.5h-1、1.7h-1、1.8h-1、2.0h-1, etc.
The following detailed description of the invention and the advantages of the invention will be presented by way of specific examples, which are intended to facilitate a better understanding of the nature and characteristics of the invention and are not intended to limit the scope of the invention.
Example 1
This example 1 provides a modified ZSM-5 molecular sieve modified by:
A certain amount of NaZSM-5 molecular sieve raw powder without template removal agent is weighed and fixed on a supergravity impact flow-rotating packed bed, and the temperature is raised to 480 ℃ by adopting a program of 5 ℃/min.
Setting the rotating speed of the super-gravity impact flow-rotating packed bed to be 1500r/min, circularly pumping dilute hydrochloric acid with the concentration of 0.5mol/L into the super-gravity impact flow-rotating packed bed through a liquid feed pipe by a liquid feed pump, enabling the mass airspeed to be 3.0h -1, and reacting for 6h by utilizing acid liquor.
After the acid liquor reaction is finished, deionized water is continuously added into the supergravity impinging stream-rotating packed bed through the liquid feed pipe, heating is stopped, and the ZSM-5 molecular sieve modified by the acid liquor is washed. Setting the rotating speed of the super-gravity impact flow-rotating packed bed to be 1000r/min, the mass space velocity WHSV to be 5.0h -1, stopping feeding deionized water after washing for 20 minutes, stopping rotating the super-gravity impact flow-rotating packed bed, and heating to 120 ℃ and keeping for 2h.
Example 2
This example 2 provides a modified ZSM-5 molecular sieve modified by:
A certain amount of NaZSM-5 molecular sieve raw powder without template removal agent is weighed and fixed on a supergravity impact flow-rotating packed bed, and the temperature is raised to 550 ℃ by adopting a program of 20 ℃/min.
Setting the rotating speed of the super-gravity impact flow-rotating packed bed to be 2000r/min, circularly pumping dilute hydrochloric acid with the concentration of 2.5mol/L into the super-gravity impact flow-rotating packed bed through a liquid feed pipe by a liquid feed pump, enabling the mass airspeed to be 0.5h -1, and reacting for 5h by utilizing acid liquor.
After the acid liquor reaction is finished, deionized water is continuously added into the supergravity impinging stream-rotating packed bed through the liquid feed pipe, heating is stopped, and the ZSM-5 molecular sieve modified by the acid liquor is washed. Setting the rotating speed of the super-gravity impact flow-rotating packed bed to be 1000r/min, the mass space velocity WHSV to be 5.0h -1, stopping feeding deionized water after washing for 22 minutes, stopping rotating the super-gravity impact flow-rotating packed bed, and heating to 115 ℃ and keeping for 2h.
Example 3
This example 3 provides a modified ZSM-5 molecular sieve modified by:
A certain amount of NaZSM-5 molecular sieve raw powder without template removal agent is weighed and fixed on a supergravity impact flow-rotating packed bed, and the temperature is raised to 700 ℃ by adopting a program of 15 ℃/min.
Setting the rotating speed of the super-gravity impact flow-rotating packed bed to be 800r/min, circularly pumping dilute nitric acid with the concentration of 1mol/L into the super-gravity impact flow-rotating packed bed through a liquid feed pipe by a liquid feed pump, and reacting for 3h by utilizing acid liquor, wherein the mass airspeed is WHSV and is 5h -1.
After the acid liquor reaction is finished, deionized water is continuously added into the supergravity impinging stream-rotating packed bed through the liquid feed pipe, heating is stopped, and the ZSM-5 molecular sieve modified by the acid liquor is washed. Setting the rotating speed of the super-gravity impact flow-rotating packed bed to be 900r/min, the mass space velocity WHSV to be 5.5h -1, stopping feeding deionized water after washing for 25 minutes, stopping rotating the super-gravity impact flow-rotating packed bed, and heating to 115 ℃ and keeping for 2h.
Example 4
This example 4 provides a modified ZSM-5 molecular sieve modified by:
A certain amount of NaZSM-5 molecular sieve raw powder without template removal agent is weighed and fixed on a supergravity impact flow-rotating packed bed, and the temperature is raised to 400 ℃ by adopting a program of 10 ℃/min.
Setting the rotating speed of the super-gravity impact flow-rotating packed bed to be 1500r/min, circularly pumping dilute nitric acid with the concentration of 0.5mol/L into the super-gravity impact flow-rotating packed bed through a liquid feed pipe by a liquid feed pump, enabling the mass airspeed to be 2h -1, and reacting for 4h by utilizing acid liquor.
After the acid liquor reaction is finished, deionized water is continuously added into the supergravity impinging stream-rotating packed bed through the liquid feed pipe, heating is stopped, and the ZSM-5 molecular sieve modified by the acid liquor is washed. Setting the rotating speed of the super-gravity impact flow-rotating packed bed to be 1000r/min, the mass space velocity WHSV to be 5.0h -1, stopping feeding deionized water after washing for 20 minutes, stopping rotating the super-gravity impact flow-rotating packed bed, and heating to 120 ℃ and keeping for 2h.
Example 5
This example 5 provides a modified ZSM-5 molecular sieve modified by:
A certain amount of NaZSM-5 molecular sieve raw powder without template removal agent is weighed and fixed on a supergravity impact flow-rotating packed bed, and the temperature is raised to 640 ℃ by adopting a program of 10 ℃/min.
Setting the rotating speed of the super-gravity impact flow-rotating packed bed to be 1800r/min, circularly pumping citric acid with the concentration of 0.1mol/L into the super-gravity impact flow-rotating packed bed through a liquid feeding pipe by a liquid feeding pump, and reacting for 4h by utilizing acid liquor, wherein the mass airspeed is 8h -1 WHSV.
After the acid liquor reaction is finished, deionized water is continuously added into the supergravity impinging stream-rotating packed bed through the liquid feed pipe, heating is stopped, and the ZSM-5 molecular sieve modified by the acid liquor is washed. Setting the rotating speed of the super-gravity impact flow-rotating packed bed to 950r/min, the mass space velocity WHSV to 6.0h -1, washing for 15 min, stopping feeding deionized water, stopping rotating the super-gravity impact flow-rotating packed bed, heating to 120 ℃ and keeping for 2h.
Example 6
This example 6 provides a modified ZSM-5 molecular sieve modified by:
A certain amount of NaZSM-5 molecular sieve raw powder without template removal agent is weighed and fixed on a supergravity impact flow-rotating packed bed, and the temperature is raised to 550 ℃ by adopting a program of 15 ℃/min.
Setting the rotating speed of the super-gravity impact flow-rotating packed bed to be 1500r/min, circularly pumping phosphoric acid with the concentration of 0.5mol/L into the super-gravity impact flow-rotating packed bed through a liquid feeding pipe by a liquid feeding pump, and reacting for 4h by utilizing acid liquor, wherein the mass airspeed is WHSV (gas turbine speed) is 3h -1.
After the acid liquor reaction is finished, deionized water is continuously added into the supergravity impinging stream-rotating packed bed through the liquid feed pipe, heating is stopped, and the ZSM-5 molecular sieve modified by the acid liquor is washed. Setting the rotating speed of the super-gravity impact flow-rotating packed bed to be 1000r/min, the mass space velocity WHSV to be 4.5h -1, stopping feeding deionized water after washing for 20 minutes, stopping rotating the super-gravity impact flow-rotating packed bed, and heating to 110 ℃ and keeping for 2h.
Comparative example 1
Preparation of HZSM-5 molecular sieve
The HZSM-5 molecular sieve related to the comparative example 1 is obtained by adopting the traditional ammonium exchange and roasting, and the preparation method comprises the following steps:
(1) Roasting the template removing agent: a certain amount of NaZSM-5 molecular sieve raw powder without template agent is weighed and placed in a muffle furnace, the temperature is programmed to 550 ℃ at 2 ℃/min, and the mixture is roasted for 6 hours at 550 ℃ to obtain a 1.
(2) Ammonium exchange and roasting: weighing a certain amount of a 1 in a beaker, adding 1.0mol/L ammonium chloride solution, sealing by using a preservative film, and fully stirring. Stirring was continued in a constant temperature water bath at 80℃for 4h. And after the water bath is finished, cooling to room temperature, filtering, washing a filter cake with deionized water until the filtrate becomes neutral, and finally, placing the filter cake in a 120 ℃ oven and drying for 12 hours. Placing the mixture in a muffle furnace, programming the temperature to 520 ℃ at 2 ℃/min, and roasting the mixture at 520 ℃ for 6 hours to obtain a 2.
(3) Secondary ammonium exchange and roasting: repeating the ammonium exchange and roasting steps of a 2 to obtain the HZSM-5 molecular sieve a 3.
Comparative example 2
Preparation of non-supergravity modified ZSM-5 molecular sieve
The method for treating the modified ZSM-5 molecular sieve under the non-hypergravity condition in the comparative example 2 comprises the following steps:
(1) Modifying ZSM-5 molecular sieve under non-hypergravity condition: and (3) weighing a certain amount of NaZSM-5 molecular sieve raw powder without template removal agent, fixing the powder on a supergravity impact flow-rotating packing bed, heating to 480 ℃ by adopting a 5 ℃/min program, setting the rotating speed of the supergravity impact flow-rotating packing bed to be 0r/min, circularly pumping 0.5mol/L dilute hydrochloric acid by a liquid feeding pump, and reacting for 4 hours at a mass airspeed of WHSV=3h -1 to obtain b 1.
(2) Washing and drying: changing liquid feeding into deionized water, stopping heating, setting the rotating speed of a supergravity device to 1000r/min, setting the mass airspeed to WHSV=5.0 h -1, washing for 20min, stopping liquid feeding, stopping rotating, and heating to 120 ℃ and keeping for 2h to obtain b 2.
Comparative example 3
The comparative example relates to a traditional modified ZSM-5 molecular sieve treatment method, which comprises the following steps:
(1) Roasting the template removing agent: a certain amount of commercial ZSM-5 molecular sieve raw powder is weighed and placed in a muffle furnace, the temperature is programmed to 550 ℃ at 2 ℃/min, and the mixture is roasted for 6 hours at 550 ℃ to obtain c 1.
(2) Ammonium exchange and roasting: weighing a certain amount of c 1 in a beaker, adding 1.0mol/L ammonium chloride solution, sealing by using a preservative film, and fully stirring. Stirring was continued in a constant temperature water bath at 80℃for 4h. And after the water bath is finished, cooling to room temperature, filtering, washing a filter cake with deionized water until the filtrate becomes neutral, and finally, placing the filter cake in a 120 ℃ oven and drying for 12 hours. Placing the mixture in a muffle furnace, programming the temperature to 520 ℃ at 2 ℃/min, and roasting the mixture at 520 ℃ for 6 hours to obtain c 2.
(3) Secondary ammonium exchange and roasting: repeating the ammonium exchange and roasting steps of c 2 to obtain c 3.
(4) And (3) hydrothermal modification: the molecular sieve c 3 is treated at 480 ℃ for 4 hours by introducing 100% of water vapor according to the WHSV of 1h -1, thus obtaining c 4.
(5) Citric acid treatment: placing the c 4 in a beaker, adding 1.2mol/L citric acid, sealing with a preservative film, and stirring thoroughly, wherein the solid-liquid mass ratio is 1:10. Stirring was continued in a constant temperature water bath at 65℃for 6h. And after the water bath is finished, cooling to room temperature, filtering, washing a filter cake with deionized water until the filtrate becomes neutral, and finally, placing the filter cake in a baking oven at 120 ℃ and drying for 12 hours to obtain c 5.
Test example 1
In order to prove the technical effect of the method provided by the embodiment of the invention on the regulation and control of the acid distribution (B acid and L acid distribution) of the modified ZSM-5 molecular sieve, pyridine IS used as an adsorbant, and the content of B acid and L acid in the modified ZSM-5 molecular sieve provided by each embodiment and comparative example IS measured by using a Nicolet IS50 type Fourier transform infrared spectrometer of THERMAL FISHER company in the United states, and the test results are shown in Table 1.
TABLE 1 Py-FTIR characterization of ZSM-5 molecular sieves treated in examples and comparative examples
As is clear from Table 1, the acidity and acid amount of the sample of comparative example 3, which was subjected to the conventional hydrothermal modification method, were greatly improved as compared with the acid amount of HZSM-5 obtained in comparative example 1, but the B acid amount was still high, and the B/L value was 0.6, which easily caused cracking reaction. The modified ZSM-5 molecular sieves provided in examples 1 to 6 of the present invention have a greatly reduced amount of B acid, a suitably increased amount of L acid, and a greatly reduced amount of strong acid, and have a B/L ratio of less than 0.2, and a ratio of (weak acid + medium strong acid)/strong acid ratio of greater than 3.
Test example 2
In order to prove the technical effect of the scheme provided by the embodiment of the invention on the regulation and control of the ZSM-5 molecular sieve pore channel structure, the specific surface area, pore structure and other structural parameters of the different modified ZSM-5 molecular sieves are measured by adopting an ASAP 2460 full-automatic adsorption instrument of Mciromeritics company in the United states, and the results are shown in Table 2.
TABLE 2 BET characterization results of ZSM-5 molecular sieves treated in examples and comparative examples
As can be seen from the data in Table 2, the modified ZSM-5 molecular sieves of examples 1-6 of the invention have a much improved specific surface area and pore volume over the conventional HZSM-5 prior to modification (provided in comparative example 1). The conventional modification methods (comparative example 2 and comparative example 3) also have some improvement in the pore structure, but have some difference from the examples of the present invention.
Test example 3
Catalysts were prepared according to table 3 and used for the catalytic alkane isomerization under different conditions, respectively, with the above examples and comparative examples, and the results of the catalytic reactions obtained are shown in table 4.
As can be seen from the data in Table 4, ① the modified ZSM-5 molecular sieve provided by the embodiment of the invention has excellent medium temperature alkane isomerization reaction catalyzing capacity, even if the reaction is carried out at a low temperature of 200 ℃, the conversion rate can still reach more than 70%, and the total isomerization selectivity reaches 90%. Wherein the catalyst provided in example 1 has an n-octane conversion of 70.6% at 200 ℃ while the total selectivity of isomerization is maintained at 78.3%, the selectivity of C8 double branched chain is 12.0%, and the yield of C8 double branched chain isomer is 8.4%.
② Example 3 is a modified ZSM-5 molecular sieve obtained by using the modification method of the invention, and has higher isomerization performance even under the condition of loading non-noble metals such as Ni/Mo and the like.
③ The modification of the support of comparative example 1 resulted in cracking reactions occurring because the acidity was not improved.
④ The traditional modified ZSM-5 molecular sieve adopted in the comparative example 3 improves the acidity of the molecular sieve to a certain extent, improves the isomerization selectivity of octane, and has far worse effect than the modified ZSM-5 carrier catalyst obtained by the invention.
As can be seen from Table 4, compared with each comparative example, the catalyst using the modified ZSM-5 molecular sieve as a carrier provided by the example of the invention has higher alkane isomer selectivity, double branched alkane isomer selectivity and liquid yield, and has remarkable isomerization performance advantages. Therefore, even if the catalyst taking the modified ZSM-5 molecular sieve obtained by the modification method as a carrier reacts at a low temperature of 200 ℃ with a dehydrogenation center serving as Ni/Mo non-noble metal, the catalyst still has higher reactivity, high isomerization selectivity and more excellent isomerization performance. In addition, the catalyst prepared by the modification method provided by the embodiment of the invention can use non-noble metal as an active component, has the advantages of simple process, low pollution discharge, energy conservation, low cost and good economic benefit and industrialization potential.
Table 3 preparation of catalyst and conditions for application in alkane isomerization reactions
Table 4 n-octane isomerization characterization results for each of the examples and comparative examples
| X％ | SMB | SDB | S | S＜C8 | Y | YDB | |
| Example 1 | 70.6 | 78.3 | 12.0 | 90.2 | 9.8 | 63.7 | 8.4 |
| Example 2 | 70.5 | 78.6 | 11.9 | 90.5 | 9.5 | 63.8 | 8.4 |
| Example 3 | 79.8 | 76.9 | 11.9 | 88.8 | 11.2 | 70.9 | 9.5 |
| Example 4 | 84.3 | 69.4 | 12.8 | 82.2 | 17.8 | 69.3 | 10.8 |
| Example 5 | 85.1 | 58.3 | 12.4 | 70.7 | 29.3 | 60.1 | 10.5 |
| Example 6 | 79.6 | 77.5 | 11.8 | 89.3 | 10.7 | 71.1 | 9.4 |
| Comparative example 1 | 91.2 | 8.5 | 1.4 | 9.9 | 90.1 | 9.1 | 1.3 |
| Comparative example 2 | 70.5 | 35.2 | 2.0 | 37.2 | 62.8 | 26.2 | 1.4 |
| Comparative example 3 | 77.2 | 39.5 | 2.3 | 41.8 | 58.2 | 32.3 | 1.8 |
Remarks: x-n-octane conversion; s MB -single branched octane isomer selectivity; s DB -selectivity of the two-branched octane isomer; total selectivity of S-isooctane product; s ＜C8 -cracking selectivity; y-octane isomer yield; y DB -di-branched octane isomer yield.
The foregoing description is only for the convenience of those skilled in the art to understand the technical solution of the present invention, and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The modification method of the ZSM-5 molecular sieve is characterized by comprising the following steps of: providing a ZSM-5 molecular sieve without template removal;
Placing the ZSM-5 molecular sieve without the template agent in a supergravity impact flow-rotating packed bed, heating to a reaction temperature, and adding acid liquor into the supergravity impact flow-rotating packed bed through a liquid feed pipe for reaction;
After the reaction is finished, deionized water is continuously added into the supergravity impinging stream-rotating packed bed through the liquid feed pipe, the ZSM-5 molecular sieve modified by the acid liquor is washed, and then drying treatment is carried out, so that the modified ZSM-5 molecular sieve is obtained;
When the acid liquor reacts with the ZSM-5 molecular sieve without the template agent, the reaction temperature is 400-700 ℃, the temperature is raised to the reaction temperature at the speed of 5-20 ℃/min, and the reaction time is 3-8 h;
the B/L value of the modified ZSM-5 molecular sieve is smaller than 0.2, and the weak acid value plus the medium strong acid value/strong acid value is larger than 3.
2. The method for modifying a ZSM-5 molecular sieve according to claim 1, wherein the ZSM-5 molecular sieve without the template agent has a silica-alumina ratio of 30 to 60.
3. The method for modifying a ZSM-5 molecular sieve according to claim 1, wherein the rotation speed of the super gravity impinging stream-rotating packed bed is 800r/min to 2000r/min when the acid solution is used to react with the ZSM-5 molecular sieve without the template agent.
4. The method for modifying a ZSM-5 molecular sieve according to claim 1, wherein the acid solution is at least one selected from the group consisting of nitric acid, hydrochloric acid, citric acid and phosphoric acid, and the mass space velocity of the acid solution is 0.5h -1～8.0h-1.
5. The method for modifying a ZSM-5 molecular sieve according to claim 1, wherein when the acid solution is reacted with the ZSM-5 molecular sieve without the template agent, the reaction temperature is 400 to 700 ℃, the temperature is raised to the reaction temperature at a rate of 5 to 20 ℃/min, and the reaction time is 3 to 8 hours.
6. The method for modifying a ZSM-5 molecular sieve according to claim 1, wherein the rotation speed of the super gravity impinging stream-rotating packed bed is 800r/min to 1000r/min when the ZSM-5 molecular sieve modified with an acid solution is washed with deionized water.
7. The method for modifying a ZSM-5 molecular sieve according to claim 6, wherein when the ZSM-5 molecular sieve modified by the acid solution is washed by deionized water, the mass space velocity of the deionized water is 3.0h -1～6.0h-1, the washing temperature is 100-120 ℃, and the washing time is 10-30 min.
8. A ZSM-5 molecular sieve catalyst, characterized in that the ZSM-5 molecular sieve catalyst comprises: a modified ZSM-5 molecular sieve, and an active component supported on the modified ZSM-5 molecular sieve;
Wherein the modified ZSM-5 molecular sieve is prepared by the modification method of the ZSM-5 molecular sieve according to any one of claims 1 to 7.
9. The ZSM-5 molecular sieve catalyst of claim 8, wherein the active component is selected from at least one of Pt metal, pd metal, rh metal, ni metal, W metal, mo metal.
10. The ZSM-5 molecular sieve catalyst according to claim 8 or 9, characterized in that the ZSM-5 molecular sieve catalyst has a particle size of 20-40 mesh.
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