CN115160182B - Method for producing salicylonitrile by methyl salicylate continuous method - Google Patents
Method for producing salicylonitrile by methyl salicylate continuous method Download PDFInfo
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- CN115160182B CN115160182B CN202210965660.8A CN202210965660A CN115160182B CN 115160182 B CN115160182 B CN 115160182B CN 202210965660 A CN202210965660 A CN 202210965660A CN 115160182 B CN115160182 B CN 115160182B
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- methyl salicylate
- salicylonitrile
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- OSWPMRLSEDHDFF-UHFFFAOYSA-N methyl salicylate Chemical compound COC(=O)C1=CC=CC=C1O OSWPMRLSEDHDFF-UHFFFAOYSA-N 0.000 title claims abstract description 178
- CHZCERSEMVWNHL-UHFFFAOYSA-N 2-hydroxybenzonitrile Chemical compound OC1=CC=CC=C1C#N CHZCERSEMVWNHL-UHFFFAOYSA-N 0.000 title claims abstract description 90
- 229960001047 methyl salicylate Drugs 0.000 title claims abstract description 89
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 29
- 238000011437 continuous method Methods 0.000 title claims abstract description 12
- 238000006243 chemical reaction Methods 0.000 claims abstract description 96
- 229910052751 metal Inorganic materials 0.000 claims abstract description 61
- 239000002184 metal Substances 0.000 claims abstract description 61
- 238000000034 method Methods 0.000 claims abstract description 56
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims abstract description 51
- 239000002808 molecular sieve Substances 0.000 claims abstract description 49
- 239000003054 catalyst Substances 0.000 claims abstract description 48
- URRHWTYOQNLUKY-UHFFFAOYSA-N [AlH3].[P] Chemical class [AlH3].[P] URRHWTYOQNLUKY-UHFFFAOYSA-N 0.000 claims abstract description 37
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 35
- 238000004821 distillation Methods 0.000 claims abstract description 35
- 239000000047 product Substances 0.000 claims abstract description 29
- 230000008569 process Effects 0.000 claims abstract description 23
- 238000000746 purification Methods 0.000 claims abstract description 21
- 239000012043 crude product Substances 0.000 claims abstract description 16
- -1 nitrile compounds Chemical class 0.000 claims abstract description 12
- 238000003756 stirring Methods 0.000 claims description 63
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 40
- 239000000843 powder Substances 0.000 claims description 38
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 37
- ILRRQNADMUWWFW-UHFFFAOYSA-K aluminium phosphate Chemical compound O1[Al]2OP1(=O)O2 ILRRQNADMUWWFW-UHFFFAOYSA-K 0.000 claims description 30
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical group CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 claims description 24
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 24
- 239000008367 deionised water Substances 0.000 claims description 24
- 229910021641 deionized water Inorganic materials 0.000 claims description 24
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 20
- 238000001035 drying Methods 0.000 claims description 19
- 239000007787 solid Substances 0.000 claims description 19
- 229910052782 aluminium Inorganic materials 0.000 claims description 14
- 238000001354 calcination Methods 0.000 claims description 11
- 239000007864 aqueous solution Substances 0.000 claims description 10
- 150000003839 salts Chemical class 0.000 claims description 10
- VXAUWWUXCIMFIM-UHFFFAOYSA-M aluminum;oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Al+3] VXAUWWUXCIMFIM-UHFFFAOYSA-M 0.000 claims description 9
- 238000001816 cooling Methods 0.000 claims description 9
- 238000002425 crystallisation Methods 0.000 claims description 9
- 230000008025 crystallization Effects 0.000 claims description 9
- 230000007935 neutral effect Effects 0.000 claims description 9
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 9
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 9
- 238000012216 screening Methods 0.000 claims description 9
- 239000011949 solid catalyst Substances 0.000 claims description 9
- 238000005406 washing Methods 0.000 claims description 9
- 239000003795 chemical substances by application Substances 0.000 claims description 8
- 230000032683 aging Effects 0.000 claims description 3
- 229910021529 ammonia Inorganic materials 0.000 claims description 3
- 238000010790 dilution Methods 0.000 claims description 3
- 239000012895 dilution Substances 0.000 claims description 3
- 238000003837 high-temperature calcination Methods 0.000 claims description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 2
- 238000010924 continuous production Methods 0.000 claims description 2
- 239000007788 liquid Substances 0.000 claims description 2
- 229910052759 nickel Inorganic materials 0.000 claims description 2
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 abstract description 16
- 239000006227 byproduct Substances 0.000 abstract description 15
- 239000002994 raw material Substances 0.000 abstract description 8
- 238000002360 preparation method Methods 0.000 abstract description 6
- 239000000126 substance Substances 0.000 abstract description 3
- 239000005457 ice water Substances 0.000 description 22
- 238000011084 recovery Methods 0.000 description 18
- 239000006185 dispersion Substances 0.000 description 14
- 238000006297 dehydration reaction Methods 0.000 description 11
- 239000000203 mixture Substances 0.000 description 11
- SKZKKFZAGNVIMN-UHFFFAOYSA-N Salicilamide Chemical compound NC(=O)C1=CC=CC=C1O SKZKKFZAGNVIMN-UHFFFAOYSA-N 0.000 description 10
- 229960000581 salicylamide Drugs 0.000 description 10
- 238000011068 loading method Methods 0.000 description 9
- 229910021645 metal ion Inorganic materials 0.000 description 9
- 239000002253 acid Substances 0.000 description 8
- 230000018044 dehydration Effects 0.000 description 8
- YGSDEFSMJLZEOE-UHFFFAOYSA-N salicylic acid Chemical compound OC(=O)C1=CC=CC=C1O YGSDEFSMJLZEOE-UHFFFAOYSA-N 0.000 description 8
- 230000003197 catalytic effect Effects 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 239000002245 particle Substances 0.000 description 7
- 239000000243 solution Substances 0.000 description 6
- 229910001220 stainless steel Inorganic materials 0.000 description 6
- 239000010935 stainless steel Substances 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 4
- 239000000543 intermediate Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- FJKROLUGYXJWQN-UHFFFAOYSA-N papa-hydroxy-benzoic acid Natural products OC(=O)C1=CC=C(O)C=C1 FJKROLUGYXJWQN-UHFFFAOYSA-N 0.000 description 4
- 229960004889 salicylic acid Drugs 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 238000006114 decarboxylation reaction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 238000001953 recrystallisation Methods 0.000 description 3
- 238000003786 synthesis reaction Methods 0.000 description 3
- 230000002194 synthesizing effect Effects 0.000 description 3
- BURBNIPKSRJAIQ-UHFFFAOYSA-N 2-azaniumyl-3-[3-(trifluoromethyl)phenyl]propanoate Chemical compound OC(=O)C(N)CC1=CC=CC(C(F)(F)F)=C1 BURBNIPKSRJAIQ-UHFFFAOYSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 238000007171 acid catalysis Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 150000001408 amides Chemical class 0.000 description 2
- 238000004176 ammonification Methods 0.000 description 2
- 229940063284 ammonium salicylate Drugs 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- ORIHZIZPTZTNCU-YVMONPNESA-N salicylaldoxime Chemical compound O\N=C/C1=CC=CC=C1O ORIHZIZPTZTNCU-YVMONPNESA-N 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000007806 chemical reaction intermediate Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 125000005842 heteroatom Chemical group 0.000 description 1
- 239000013067 intermediate product Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000004973 liquid crystal related substance Substances 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000012229 microporous material Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 239000000575 pesticide Substances 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 229960001860 salicylate Drugs 0.000 description 1
- 239000011973 solid acid Substances 0.000 description 1
- 235000013599 spices Nutrition 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C253/00—Preparation of carboxylic acid nitriles
- C07C253/22—Preparation of carboxylic acid nitriles by reaction of ammonia with carboxylic acids with replacement of carboxyl groups by cyano groups
-
- 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
- B01J29/82—Phosphates
- B01J29/84—Aluminophosphates containing other elements, e.g. metals, boron
-
- 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
- B01J2229/10—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
- B01J2229/183—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself in framework positions
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/584—Recycling of catalysts
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Catalysts (AREA)
Abstract
The application belongs to the field of organic chemical industry, relates to preparation of nitrile compounds, and in particular relates to a method for producing salicylonitrile by using a methyl salicylate continuous method. Specifically, methyl salicylate and ammonia gas are introduced into a fixed bed reactor filled with a catalyst, and react at the reaction temperature of 320-420 ℃ and under normal pressure, and a crude product is purified to obtain a salicylonitrile product; the catalyst is a metal modified phosphorus-aluminum molecular sieve. According to the application, methyl salicylate is used as a raw material, a metal modified phosphorus-aluminum molecular sieve is used as a catalyst, the salicylonitrile is continuously produced in a fixed bed reactor, and the crude product is purified by a two-stage reduced pressure distillation process to obtain a salicylonitrile product, so that the continuity of the salicylonitrile purification process is realized, the process flow is simplified, and the production efficiency is improved. Compared with the prior art, the method reduces the generation of byproduct phenol, improves the conversion rate of methyl salicylate and the selectivity of salicylonitrile, and reduces the difficulty of purifying the salicylonitrile.
Description
Technical Field
The application belongs to the field of organic chemical industry, relates to preparation of nitrile compounds, and in particular relates to a method for producing salicylonitrile by using a methyl salicylate continuous method.
Background
Salicylonitrile is an important chemical intermediate and is widely used for synthesis and production of medicines, pesticides, spices and liquid crystal materials. The prior production process of salicylonitrile mainly comprises a salicylaldoxime dehydration method, a salicylamide dehydration method, an ammonium salicylate dehydration method, a methyl salicylate ammoniation dehydration method and the like. Wherein, the salicylaldoxime dehydration method and the salicylamide dehydration method adopt raw materials with larger toxicity as dehydrating agents and generate a large amount of acid wastewater to cause environmental pollution, and the patent CN102174002A discloses a method for synthesizing salicylonitrile by taking ammonium salicylate as raw materials. However, the preparation process of the catalyst in the method is complex, the solvent is various, the reaction time is long, and the method is unfavorable for practical production and application.
In comparison, the continuous production can be realized by adopting methyl salicylate and ammonia gas as raw materials, and the process flow is simplified. Patent CN110698362a discloses a process for synthesizing salicylonitrile by adopting a continuous method, wherein methyl salicylate, a water vapor mixture and ammonia gas from a gasification chamber are respectively introduced into a two-stage fluidized bed and reacted under the action of a vanadium-supported catalyst to obtain salicylonitrile gas, so that reacted materials are rapidly mixed in the fluidized bed and reaction heat is timely removed, uneven concentration distribution and local overheating in a traditional reactor can be overcome, and the mixing of the reacted materials and the mass transfer and heat transfer processes can be effectively controlled. The generating capacity is improved, and the labor intensity is reduced. However, the water vapor treatment process increases the generation of byproduct phenol, which results in reduced yield of salicylnitrile and further increases the difficulty of purifying salicylnitrile. Impurities in the crude salicylnitrile product mainly include unreacted methyl salicylate, by-product salicylamide, and phenol. At present, a recrystallization method is mainly adopted for purifying the salicylonitrile, a large amount of solvent is needed, the recovery of the solvent, the drying of the product salicylonitrile and the like are involved in the process, the operation process is complex, and the efficiency is low. Therefore, how to reduce the generation of byproducts in the reaction and improve the conversion rate of methyl salicylate and the selectivity of salicylonitrile is a technical problem to be solved.
The information disclosed in this background section is only for enhancement of understanding of the general background of the application and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is known to a person skilled in the art.
Disclosure of Invention
The application aims to provide a method for continuously producing salicylonitrile by taking methyl salicylate as a raw material. By modifying the catalyst, the generation of byproducts in the reaction is reduced, and the conversion rate of methyl salicylate and the selectivity of salicylonitrile are improved.
In order to achieve the above purpose, the application adopts the following technical scheme:
a method for producing salicylonitrile by using methyl salicylate continuous method comprises the steps of introducing methyl salicylate and ammonia gas into a fixed bed reactor filled with a catalyst, reacting at 320-420 ℃ under normal pressure, and purifying a crude product to obtain a salicylnitrile product; the catalyst is a metal modified phosphorus-aluminum molecular sieve. According to the application, metal modification is carried out on the phosphorus-aluminum molecular sieve, hetero atoms are introduced into the phosphorus-aluminum molecular sieve skeleton through unequal substitution of skeleton atoms, at the moment, charge balance in the phosphorus-aluminum molecular sieve skeleton is broken, and through isomorphous substitution, the phosphorus-aluminum molecular sieve generates an acid center, so that the phosphorus-aluminum molecular sieve modified by metal has the property of solid acid, methyl salicylate can be ensured to react under the condition of acid catalysis, the conversion rate of methyl salicylate is improved, in addition, the phosphorus-aluminum molecular sieve has good thermal stability and hydrothermal stability as a typical microporous material, can resist the influence of high temperature and water generation in the process of ammonification-dehydration of methyl salicylate to salicylonitrile, has excellent structural stability, thereby avoiding the influence of generated water on the surface acidity of a catalyst and ensuring the stable catalytic reaction.
The process of generating salicylonitrile by methyl salicylate reaction comprises ammonolysis-dehydration reaction, namely, methyl salicylate is ammonolyzed under the action of ammonia to generate salicylamide, the salicylamide is dehydrated to generate salicylonitrile, the two steps of reactions are carried out under the condition of acid catalysis, but the strong acid site in the system easily causes hydrolysis-decarboxylation reaction of methyl salicylate and intermediate salicylamide, so that water sample amide is hydrolyzed to generate salicylic acid, and then salicylic acid is decarboxylated to generate phenol, so that the content of byproduct phenol is increased.
Further, the liquid hourly space velocity of the methyl salicylate in the reaction process is 0.1-0.5 h -1 . When the airspeed is too low, the salicylnitrile generated by the reaction isThe residence time in the system is prolonged, so that byproducts such as phenol and the like are generated, and the selectivity of target products is influenced; if the airspeed is too high, incomplete conversion of methyl salicylate and intermediate salicylamide can be caused, and the product yield is affected.
Further, the molar ratio of ammonia gas to methyl salicylate is 6-16:1. When the amount of ammonia is too low, not only the conversion rate of methyl salicylate is reduced, but also the formation of by-product phenol is easily caused. Too high ammonia gas can increase subsequent recovery processing load, affecting process economy. The application sets a little excessive ammonia gas, ensures that the salicylamide as a reaction intermediate is converted into salicylonitrile with high selectivity, and does not influence the difficulty of recovery treatment.
Further, in the metal modified phosphorus aluminum molecular sieve, the modified metal is one or more of Co, fe, ni, mn, zn and Cu, the mole fraction of the modified metal in the total metal is 1-10%, and the total metal is the sum of the modified metal and aluminum. When the content of the modified metal is too low, the number of acid sites on the surface of the catalyst is low, so that the catalytic reaction efficiency is reduced, and the conversion rate of methyl salicylate is affected; when the content of the modified metal is too high, the number of the surface acidity is high, so that hydrolysis-decarboxylation reaction of raw material methyl salicylate and intermediate salicylamide is easy to occur, phenol byproducts are generated, and the selectivity of the product salicylnitrile is further reduced. According to the application, the metal modified phosphorus-aluminum molecular sieve catalyst is used, and the content of modified metal is controlled, so that the generation of byproduct phenol is reduced in the reaction process, and the subsequent purification difficulty is reduced.
Further, the metal modified phosphorus aluminum molecular sieve is prepared according to the following method:
s1: placing pseudo-boehmite and deionized water in a reaction bottle, vigorously stirring at normal temperature for 20-40 min to obtain alumina sol, slowly dripping phosphoric acid into the alumina sol after dilution, vigorously stirring, keeping the temperature of a reaction system within 45 ℃, and continuously stirring for 20-40 min after dripping is completed to obtain uniformly dispersed aluminum phosphate sol;
s2: preparing a modified metal salt aqueous solution, dropwise adding the modified metal salt aqueous solution into the aluminum phosphate sol at room temperature, and stirring vigorously, and continuing stirring for 20-40 min after the dropwise adding is finished;
s3: slowly dropwise adding a template agent into the aluminum phosphate sol treated in the step S2, and vigorously stirring, wherein the temperature of a reaction system is kept within 30 ℃, and after the dropwise adding is finished, stirring is continued for 100-150 min to obtain an initial sol;
s4: aging the initial sol for 10-15 hours, transferring the initial sol into a high-pressure reaction kettle with polytetrafluoroethylene as a lining, raising the temperature to 170-200 ℃ at a speed of 5 ℃/min, crystallizing at constant temperature for 36-50 hours after the temperature is stable, cooling after crystallization, and washing the obtained sol with deionized water until the pH value of an eluate is neutral to obtain phosphorus-aluminum molecular sieve raw powder;
s5: drying the phosphorus-aluminum molecular sieve raw powder in a constant-temperature drying oven at 50-70 ℃ for 10-15 hours, and calcining at high temperature for 20-30 hours to obtain metal modified APO-5 molecular sieve solid powder;
s6: and tabletting, forming, crushing and screening the solid powder to obtain the solid catalyst with 20-40 meshes.
Preferably, the metal modified phosphorus aluminum molecular sieve is prepared according to the following method:
s1: placing pseudo-boehmite and deionized water into a reaction bottle, vigorously stirring for 25-35 min at normal temperature to obtain milky alumina sol, slowly dripping 85% phosphoric acid into the alumina sol after dilution, vigorously stirring, controlling the dripping speed, and placing the reaction bottle into ice water to keep the temperature of a reaction system within 45 ℃. And after the dripping is finished, continuing stirring for 25-35 min to obtain the aluminum phosphate sol with uniform dispersion.
S2: preparing a modified metal salt aqueous solution, dropwise adding the modified metal salt aqueous solution into the aluminum phosphate sol at room temperature, and stirring vigorously to ensure uniform metal ion dispersion. And after the dripping is finished, continuing stirring for 25-35 min.
S3: slowly dripping the template agent into the aluminum phosphate sol treated in the step S2, vigorously stirring, controlling the dripping speed, and placing a reaction bottle in ice water to keep the temperature of a reaction system within 30 ℃. And after the dripping is finished, continuously stirring for 120-150 min to obtain initial sol.
S4: and (3) aging the initial sol for 11-13 hours, transferring the initial sol into a high-pressure reaction kettle with polytetrafluoroethylene as a lining, raising the temperature to 170-190 ℃ at a speed of 5 ℃/min, and crystallizing at constant temperature for 40-50 hours after the temperature is stable. And after crystallization, the high-pressure reaction kettle is placed into ice water for rapid cooling. And then washing the obtained sol with deionized water until the pH value of the eluate is neutral, thus obtaining the phosphorus-aluminum molecular sieve raw powder.
S5: and drying the phosphorus-aluminum molecular sieve raw powder in a constant temperature drying oven at 60-70 ℃ for 12-14 h, and then calcining at high temperature for 20-25 h to obtain metal modified APO-5 molecular sieve solid powder.
S6: and tabletting, forming, crushing and screening the solid powder to obtain the solid catalyst with 20-40 meshes.
Further, in the step S1, the concentration of the diluted phosphoric acid is 20-40%. When the volume of the alumina sol is about 50-mL, the dripping rate is 2-6 mL/min. In the step, phosphoric acid is dripped into the alumina sol to be a reaction process with obvious heat release, the heating speed of the reaction is controlled by controlling the concentration and dripping speed of the phosphoric acid, and the quality stability of the catalyst is ensured by placing a reaction bottle in ice water so as to keep the temperature of a reaction system within 45 ℃, the uniformity of a synthesis system is influenced by the overhigh system temperature, and molecular sieves with other structures are generated so as to influence the quality of a catalyst product and the stability of catalytic performance; and too low concentration of phosphoric acid or too low drop acceleration can affect the preparation efficiency of the catalyst, thereby increasing the production cost.
In the step S2, the concentration of the modified metal salt aqueous solution is 0.5-2.5 mol/L. When the volume of the aluminum phosphate sol is about 70 and mL, the dripping rate is 0.5-4 mL/min. The too high concentration or the too high dropping speed of the modified metal salt aqueous solution can influence the dispersibility of metal ions in the system, so that molecular sieves with other structures are generated, and the quality and the catalytic performance of the catalyst product are influenced; too low a concentration of the aqueous solution of the modified metal salt or too slow a dropping rate may affect the preparation efficiency of the catalyst.
Further, in the step S3, the template agent is triethylamine. When the volume of the aluminum phosphate sol is about 80 and mL, the dripping rate is 0.5-2 mL/min. The process is a strong exothermic process, and if the system temperature is too high, the effective synthesis of the phosphorus-aluminum molecular sieve can be influenced, and aluminum phosphate or hydrated phosphate with a compact structure is generated, so that the temperature of a reaction system is kept within 30 ℃. The dropping speed is too high, so that the system temperature is easy to rise, and the dropping speed is too low, so that the preparation efficiency of the catalyst is affected, and the dropping speed is not too high.
Further, in the step S5, the high-temperature calcination temperature is 500-700 ℃. The template agent is removed from the raw powder of the phosphorus-aluminum molecular sieve through high-temperature calcination, so that the metal modified APO-5 molecular sieve solid powder is prepared, if the calcination temperature is too low, the template agent cannot be completely removed, the catalyst quality is further affected, the calcination temperature is too high, the molecular sieve structure is easily damaged, and the structural stability of the metal modified phosphorus-aluminum molecular sieve catalyst is reduced.
Furthermore, the purification process adopts a two-stage reduced pressure distillation process, and the two-stage distillation process can realize the serialization of the salicylnitrile purification process, simplify the process flow and improve the production efficiency.
The distillation temperature of the first-stage reduced pressure distillation is 18-30 ℃, and the pressure is 2000-4000 Pa. The purpose of the first-stage reduced pressure distillation is to remove low boiling impurities such as methanol, water and the like; when the pressure is too low, the salicylonitrile product is easily carried out, and the reaction yield is affected. When the pressure is too high or atmospheric distillation is performed, not only the product quality is affected, but also the distillation efficiency is lowered.
The distillation temperature of the second-stage reduced pressure distillation is 108-115 ℃, and the pressure is 350-450 Pa. The purpose of the second stage of reduced pressure distillation is to collect the salicylnitrile product. The main front cut in the process is the byproduct phenol, and the pressure is too low, so that not only can the distillation energy consumption be increased, but also the phenol is easily contained in the product, and the purity of the product is influenced; too high a pressure can result in too high a distillation temperature, affecting product quality.
Compared with the prior art, the application has the following advantages and effects:
(1) According to the application, methyl salicylate is used as a raw material, a metal modified phosphorus-aluminum molecular sieve is used as a catalyst, the salicylonitrile is continuously produced in a fixed bed reactor, and the crude product is purified by a two-stage reduced pressure distillation process to obtain a salicylonitrile product, so that the continuity of the salicylonitrile purification process is realized, the process flow is simplified, and the production efficiency is improved. Compared with the prior art, the method reduces the generation of byproduct phenol, improves the conversion rate of methyl salicylate and the selectivity of salicylnitrile, reduces the difficulty of purifying the salicylnitrile, avoids the recycling problem of a large amount of solvents in the purifying process without using a recrystallization process, and has the advantages of simple operation process, high purifying efficiency and stable product quality.
(2) According to the application, the metal modified phosphorus-aluminum molecular sieve is used as the catalyst, and the content of modified metal is controlled, so that the surface of the catalyst mainly generates an acid site with medium strength, the ammonolysis-dehydration reaction of methyl salicylate is promoted, the generation of byproduct phenol is reduced in the reaction process, the conversion rate of methyl salicylate and the selectivity of salicylonitrile are ensured, and the subsequent purification difficulty is further reduced. Meanwhile, the metal modified phosphorus-aluminum molecular sieve has extremely strong catalytic activity, improves the efficiency of acid catalytic conversion reaction from ammonification and dehydration of methyl salicylate to salicylonitrile, and has better process stability; compared with the prior art, the catalyst disclosed by the application is placed in the fixed bed reactor, so that the loss of active components caused by continuous collision friction of catalyst particles in a fluidized bed process is avoided, the structural stability in the reaction process is ensured, meanwhile, the purification difficulty of a product is reduced by reducing the generation of by-product phenol, the purification of a subsequent crude product is facilitated, the implementation of a two-stage reduced pressure distillation process is promoted, and the purity and recovery rate of the product are improved.
Drawings
Fig. 1 is an XRD pattern of catalyst samples prepared in example 1, example 4, example 5 and example 6 of the present application.
Detailed Description
The present application will be described in further detail with reference to examples, but embodiments of the present application are not limited thereto.
In the examples of the present application, commercially available materials were sourced as follows:
the XRD patterns of the catalyst samples prepared in example 1, example 4, example 5 and example 6 are shown in fig. 1. It can be seen that the prepared catalysts all have AFI topological structures, the diffraction peaks have high intensity and good symmetry, diffraction peaks of other crystal phases are not found, and the introduction of metal ions does not change the AFI structure of the crystal, so that the crystallinity is higher.
Example 1
A process for preparing salicylonitrile by continuous methyl salicylate method includes such steps as loading 10 mL catalyst 5% CoAPO-5 in fixed-bed reactor, and preheating to 380 deg.C by introducing ammonia gas. Methyl salicylate was introduced into the reactor at a space velocity of 0.2. 0.2 h -1 The molar ratio of ammonia gas to methyl salicylate is 10:1. After the reaction at 380 ℃, the crude product is cooled and analyzed by a gas chromatograph to obtain the composition, the conversion rate of methyl salicylate is 98%, the selectivity of salicylnitrile is 96%, the purity of the purified salicylnitrile reaches 99% after distillation, and the recovery rate is 93%.
Further, the metal modified phosphorus aluminum molecular sieve is prepared according to the following method:
s1: 47.5g of pseudo-boehmite (70% Al) was weighed out 2 O 3 ) And 50 mL deionized water, and stirring vigorously in a reactor at normal temperature for 30 min to obtain milky alumina sol. Then 56.5g of phosphoric acid (85%) was weighed and diluted with 89 mL water. The diluted phosphoric acid solution was slowly added dropwise to the alumina sol described above. Stirring vigorously, controlling dropping speed, and placing the reaction bottle in ice water to keep the temperature of the reaction system within 50 ℃. After the dripping is finished, stirring is continued for 30 min, and the aluminum phosphate sol with uniform dispersion is obtained.
S2: 7.1g of Co (NO) was weighed out 3 ) 2 ·6H 2 O was dissolved in 20 mL deionized water (1.25 mol/L) and added dropwise to the above aluminum phosphate sol at room temperature with vigorous stirring to ensure uniform dispersion of the metal ions. After the completion of the dropwise addition, stirring was continued for 30 min.
S3: 49.6g of triethylamine is weighed and slowly added into the aluminum phosphate sol in a dropwise manner, the stirring is vigorously carried out, the dropping speed is controlled, and a reaction bottle is placed in ice water to keep the system temperature within 40 ℃. After the completion of the dropwise addition, stirring was continued for 2 h to obtain an initial sol.
S4: the initial sol obtained above is aged 12 h and then transferred into a stainless steel high-pressure reaction kettle with polytetrafluoroethylene as a lining. Raising the temperature to 180 ℃ at a speed of 5 ℃/min, and crystallizing at a constant temperature of 48 h after the temperature is stable. After crystallization, the autoclave is placed in ice water for rapid cooling. And then washing the obtained sample with deionized water until the pH value of the eluate is neutral, thus obtaining CoAPO-5 raw powder.
S5: drying the raw powder in a constant temperature drying oven at 60 ℃ for 12 h, and then calcining at 600 ℃ for 24 h to obtain solid powder, namely a molecular sieve sample with Co accounting for 5% of total metal (Co and Al) content, namely 5% CoAPO-5.
S6: and tabletting, forming, crushing and screening the solid powder to obtain the solid catalyst particles with 20-40 meshes.
Example 2
A process for preparing salicylonitrile by continuous methyl salicylate method includes such steps as loading 10 mL catalyst 1% CoAPO-5 in fixed-bed reactor, and preheating to 420 deg.C by introducing ammonia gas. Methyl salicylate was introduced into the reactor at a space velocity of 0.5. 0.5 h -1 The molar ratio of ammonia gas to methyl salicylate was 6:1. After the reaction at 420 ℃, the crude product is cooled and analyzed by a gas chromatograph to obtain the composition, the conversion rate of methyl salicylate is 87%, the selectivity of salicylnitrile is 92%, the purity of the salicylnitrile after distillation and purification reaches 98%, and the recovery rate is 92%.
Wherein, the metal modified phosphorus aluminum molecular sieve is prepared according to the following method:
s1: 49.5g of pseudo-boehmite (70% Al) was weighed out 2 O 3 ) And 52.1. 52.1 mL deionized water, and stirring vigorously in a reactor at room temperature for 30 min to give a milky alumina sol. Then 56.5g of phosphoric acid (85%) was weighed and diluted with 89 mL water. The diluted phosphoric acid solution was slowly added dropwise to the alumina sol described above. Stirring vigorously, controlling dropping speed, and placing the reaction bottle in ice water to keep the temperature of the reaction system within 50 ℃.After the dripping is finished, stirring is continued for 30 min, and the aluminum phosphate sol with uniform dispersion is obtained.
S2: 1.43g of Co (NO) was weighed out 3 ) 2 ·6H 2 O was dissolved in 10 mL deionized water (0.25 mol/L) and added dropwise to the above aluminum phosphate sol at room temperature with vigorous stirring to ensure uniform dispersion of the metal ions. After the completion of the dropwise addition, stirring was continued for 30 min.
S3: 49.6g of triethylamine is weighed and slowly added into the aluminum phosphate sol in a dropwise manner, the stirring is vigorously carried out, the dropping speed is controlled, and a reaction bottle is placed in ice water to keep the system temperature within 40 ℃. After the completion of the dropwise addition, stirring was continued for 2 h to obtain an initial sol.
S4: the initial sol obtained above is aged 12 h and then transferred into a stainless steel high-pressure reaction kettle with polytetrafluoroethylene as a lining. Raising the temperature to 180 ℃ at a speed of 5 ℃/min, and crystallizing at a constant temperature of 48 h after the temperature is stable. After crystallization, the autoclave is placed in ice water for rapid cooling. And then washing the obtained sample with deionized water until the pH value of the eluate is neutral, thus obtaining CoAPO-5 raw powder.
S5: drying the raw powder in a constant temperature drying oven at 60 ℃ for 12 h, and then calcining at 600 ℃ for 24 h to obtain solid powder, namely a molecular sieve sample with Co accounting for 1% of total metal (Co and Al), namely 1% CoAPO-5.
S6: and tabletting, forming, crushing and screening the solid powder to obtain the solid catalyst particles with 20-40 meshes.
Example 3
A process for preparing salicylonitrile by continuous methyl salicylate method includes such steps as loading 10% of mL catalyst 10% CoAPO-5 in fixed-bed reactor, and preheating to 380 deg.C by introducing ammonia gas. Methyl salicylate was introduced into the reactor at a space velocity of 0.1. 0.1 h -1 The molar ratio of ammonia gas to methyl salicylate was 16:1. After the reaction at 380 ℃, the crude product is cooled and analyzed by a gas chromatograph to obtain the composition, the conversion rate of methyl salicylate is 98%, the selectivity of salicylnitrile is 90%, the purity of the salicylnitrile after distillation and purification is 98%, and the recovery rate is 94%.
Wherein, the metal modified phosphorus aluminum molecular sieve is prepared according to the following method:
s1: 45.0g of pseudo-boehmite (70% Al) was weighed out 2 O 3 ) And 47.4. 47.4 mL deionized water, and stirring vigorously in a reactor at room temperature for 30 min to give milky alumina sol. Then 56.5g of phosphoric acid (85%) was weighed and diluted with 89 mL water. The diluted phosphoric acid solution was slowly added dropwise to the alumina sol described above. Stirring vigorously, controlling dropping speed, and placing the reaction bottle in ice water to keep the temperature of the reaction system within 50 ℃. After the dripping is finished, stirring is continued for 30 min, and the aluminum phosphate sol with uniform dispersion is obtained.
S2: weigh 14.3g Co (NO) 3 ) 2 ·6H 2 O is dissolved in 20 mL deionized water (2.5 mol/L) and added dropwise to the aluminum phosphate sol at room temperature with vigorous stirring to ensure uniform dispersion of metal ions. After the completion of the dropwise addition, stirring was continued for 30 min.
S3: 49.6g of triethylamine is weighed and slowly added into the aluminum phosphate sol in a dropwise manner, the stirring is vigorously carried out, the dropping speed is controlled, and a reaction bottle is placed in ice water to keep the system temperature within 40 ℃. After the completion of the dropwise addition, stirring was continued for 2 h to obtain an initial sol.
S4: the initial sol obtained above is aged 12 h and then transferred into a stainless steel high-pressure reaction kettle with polytetrafluoroethylene as a lining. Raising the temperature to 180 ℃ at a speed of 5 ℃/min, and crystallizing at a constant temperature of 48 h after the temperature is stable. After crystallization, the autoclave is placed in ice water for rapid cooling. And then washing the obtained sample with deionized water until the pH value of the eluate is neutral, thus obtaining CoAPO-5 raw powder.
S5: drying the raw powder in a constant temperature drying oven at 60 ℃ for 12 h, and then calcining at 600 ℃ for 24 h to obtain solid powder, namely a molecular sieve sample with 10% of Co content of total metals (Co and Al), namely 10% CoAPO-5.
S6: and tabletting, forming, crushing and screening the solid powder to obtain the solid catalyst particles with 20-40 meshes.
Example 4
A process for preparing salicyl nitrile by continuous methyl salicylate method includes such steps as loading 10 in fixed-bed reactorThe mL catalyst was 5% FeAPO-5, and ammonia gas was introduced to preheat to 320 ℃. Methyl salicylate was introduced into the reactor at a space velocity of 0.2. 0.2 h -1 The molar ratio of ammonia gas to methyl salicylate is 10:1. After the reaction at 320 ℃, the crude product is cooled and analyzed by a gas chromatograph to obtain the composition, the conversion rate of methyl salicylate is 90%, the selectivity of salicylnitrile is 95%, the purity of the salicylnitrile after distillation and purification reaches 96%, and the recovery rate is 89%.
Further, the metal modified phosphorus aluminum molecular sieve is prepared according to the following method:
s1: 47.5g of pseudo-boehmite (70% Al) was weighed out 2 O 3 ) And 50 mL deionized water, and stirring vigorously in a reactor at normal temperature for 30 min to obtain milky alumina sol. Then 56.5g of phosphoric acid (85%) was weighed and diluted with 89 mL water. The diluted phosphoric acid solution was slowly added dropwise to the alumina sol described above. Stirring vigorously, controlling dropping speed, and placing the reaction bottle in ice water to keep the temperature of the reaction system within 50 ℃. After the dripping is finished, stirring is continued for 30 min, and the aluminum phosphate sol with uniform dispersion is obtained.
S2: weigh 9.9g of Fe (NO) 3 ) 3 ·9H 2 O is dissolved in 20 mL deionized water (2.5 mol/L) and added dropwise to the aluminum phosphate sol at room temperature with vigorous stirring to ensure uniform dispersion of metal ions. After the completion of the dropwise addition, stirring was continued for 30 min.
S3: 49.6g of triethylamine is weighed and slowly added into the aluminum phosphate sol in a dropwise manner, the stirring is vigorously carried out, the dropping speed is controlled, and a reaction bottle is placed in ice water to keep the system temperature within 40 ℃. After the completion of the dropwise addition, stirring was continued for 2 h to obtain an initial sol.
S4: the initial sol obtained above is aged 12 h and then transferred into a stainless steel high-pressure reaction kettle with polytetrafluoroethylene as a lining. Raising the temperature to 180 ℃ at a speed of 5 ℃/min, and crystallizing at a constant temperature of 48 h after the temperature is stable. After crystallization, the autoclave is placed in ice water for rapid cooling. And then washing the obtained sample with deionized water until the pH value of the eluate is neutral, thus obtaining FeAPO-5 raw powder.
S5: drying the raw powder in a constant temperature drying oven at 60 ℃ for 12 h, and then calcining at 600 ℃ for 24 h to obtain solid powder, namely a molecular sieve sample with 5% of Fe (Fe and Al) content in total metal, namely 5% FeAPO-5.
S6: and tabletting, forming, crushing and screening the solid powder to obtain the solid catalyst particles with 20-40 meshes.
Example 5
A method for producing salicylonitrile by using methyl salicylate continuous method comprises the following operation steps of filling 10 mL catalyst 5% MnAPO-5 in a fixed bed reactor, and introducing ammonia gas to preheat to 420 ℃. Methyl salicylate was introduced into the reactor at a space velocity of 0.2. 0.2 h -1 The molar ratio of ammonia gas to methyl salicylate is 10:1. After the reaction at 420 ℃, the crude product is cooled and analyzed by a gas chromatograph to obtain the composition, the conversion rate of methyl salicylate is 93%, the selectivity of salicylnitrile is 81%, the purity of the salicylnitrile after distillation and purification reaches 95%, and the recovery rate is 90%.
Further, the metal modified phosphorus aluminum molecular sieve is prepared according to the following method:
s1: 47.5g of pseudo-boehmite (70% Al) was weighed out 2 O 3 ) And 50 mL deionized water, and stirring vigorously in a reactor at normal temperature for 30 min to obtain milky alumina sol. Then 56.5g of phosphoric acid (85%) was weighed and diluted with 89 mL water. The diluted phosphoric acid solution was slowly added dropwise to the alumina sol described above. Stirring vigorously, controlling dropping speed, and placing the reaction bottle in ice water to keep the temperature of the reaction system within 50 ℃. After the dripping is finished, stirring is continued for 30 min, and the aluminum phosphate sol with uniform dispersion is obtained.
S2: weigh 7.0gMn (NO) 3 ) 2 ·6H 2 O is dissolved in 20 mL deionized water (2.5 mol/L) and added dropwise to the aluminum phosphate sol at room temperature with vigorous stirring to ensure uniform dispersion of metal ions. After the completion of the dropwise addition, stirring was continued for 30 min.
S3: 49.6g of triethylamine is weighed and slowly added into the aluminum phosphate sol in a dropwise manner, the stirring is vigorously carried out, the dropping speed is controlled, and a reaction bottle is placed in ice water to keep the system temperature within 40 ℃. After the completion of the dropwise addition, stirring was continued for 2 h to obtain an initial sol.
S4: the initial sol obtained above is aged 12 h and then transferred into a stainless steel high-pressure reaction kettle with polytetrafluoroethylene as a lining. Raising the temperature to 180 ℃ at a speed of 5 ℃/min, and crystallizing at a constant temperature of 48 h after the temperature is stable. After crystallization, the autoclave is placed in ice water for rapid cooling. And then washing the obtained sample with deionized water until the pH value of the eluate is neutral, thus obtaining MnAPO-5 raw powder.
S5: drying the raw powder in a constant temperature drying oven at 60 ℃ for 12 h, and then calcining at 600 ℃ for 24 h to obtain solid powder, namely a molecular sieve sample with Mn accounting for 5% of total metal (Mn and Al) content, namely 5% MnAPO-5.
S6: and tabletting, forming, crushing and screening the solid powder to obtain the solid catalyst particles with 20-40 meshes.
Example 6
A process for preparing salicylonitrile by continuous methyl salicylate method includes such steps as loading 10 mL catalyst 5% NiAPO-5 in fixed-bed reactor, and preheating to 400 deg.C by introducing ammonia gas. Methyl salicylate was introduced into the reactor at a space velocity of 0.2. 0.2 h -1 The molar ratio of ammonia gas to methyl salicylate is 10:1. After the reaction at 400 ℃, the crude product is cooled and analyzed by a gas chromatograph to obtain the composition, the conversion rate of methyl salicylate is 94%, the selectivity of salicylnitrile is 95%, the purity of the salicylnitrile after distillation and purification reaches 99%, and the recovery rate is 93%.
Further, the metal modified phosphorus aluminum molecular sieve is prepared according to the following method:
s1: 47.5g of pseudo-boehmite (70% Al) was weighed out 2 O 3 ) And 50 mL deionized water, and stirring vigorously in a reactor at normal temperature for 30 min to obtain milky alumina sol. Then 56.5g of phosphoric acid (85%) was weighed and diluted with 89 mL water. The diluted phosphoric acid solution was slowly added dropwise to the alumina sol described above. Stirring vigorously, controlling dropping speed, and placing the reaction bottle in ice water to keep the temperature of the reaction system within 50 ℃. After the dripping is finished, stirring is continued for 30 min, and the aluminum phosphate sol with uniform dispersion is obtained.
S2: weigh 7.1gNi (NO) 3 ) 2 ·6H 2 O is dissolved in10 mL deionized water (5.0 mol/L) was added dropwise to the above aluminum phosphate sol at room temperature with vigorous stirring to ensure uniform dispersion of the metal ions. After the completion of the dropwise addition, stirring was continued for 30 min.
S3: 49.6g of triethylamine is weighed and slowly added into the aluminum phosphate sol in a dropwise manner, the stirring is vigorously carried out, the dropping speed is controlled, and a reaction bottle is placed in ice water to keep the system temperature within 40 ℃. After the completion of the dropwise addition, stirring was continued for 2 h to obtain an initial sol.
S4: the initial sol obtained above is aged 12 h and then transferred into a stainless steel high-pressure reaction kettle with polytetrafluoroethylene as a lining. Raising the temperature to 180 ℃ at a speed of 5 ℃/min, and crystallizing at a constant temperature of 48 h after the temperature is stable. After crystallization, the autoclave is placed in ice water for rapid cooling. And then washing the obtained sample with deionized water until the pH value of the eluate is neutral, thus obtaining the NiAPO-5 raw powder.
S5: drying the raw powder in a constant temperature drying oven at 60 ℃ for 12 h, and then calcining at 600 ℃ for 24 h to obtain solid powder, namely a molecular sieve sample with 5% of Ni (Ni and Al) content, which is recorded as 5% of NiAPO-5.
S6: and tabletting, forming, crushing and screening the solid powder to obtain the solid catalyst particles with 20-40 meshes.
Comparative example 1
A process for preparing salicylonitrile by continuous methyl salicylate method includes such steps as loading 10 mL alumina catalyst in fixed-bed reactor, introducing ammonia gas, and preheating to 380 deg.C. Methyl salicylate was introduced into the reactor at a space velocity of 0.2. 0.2 h -1 The molar ratio of ammonia gas to methyl salicylate is 10:1. After the reaction at 380 ℃, the crude product is cooled and analyzed by a gas chromatograph to obtain the composition, the conversion rate of methyl salicylate is 73%, the selectivity of salicylonitrile is 80%, and the purity of the purified salicylnitrile reaches 91% after distillation and purification, and the recovery rate is 86%.
Comparative example 2
A process for preparing salicylonitrile by methyl salicylate continuous method includes such steps as loading 10 mL unmodified molecular sieve of phosphorus-aluminium catalyst in fixed-bed reactor, introducing ammonia gas, and preheating to 380 deg.C. Will beMethyl salicylate was introduced into the reactor at a space velocity of 0.2. 0.2 h -1 The molar ratio of ammonia gas to methyl salicylate is 10:1. After the reaction at 380 ℃, the crude product is cooled and analyzed by a gas chromatograph to obtain the composition, the conversion rate of methyl salicylate is 90%, the selectivity of salicylonitrile is 78%, the purity of the purified salicylnitrile reaches 92% after distillation, and the recovery rate is 82%.
Comparative example 3
A process for preparing salicylonitrile by continuous methyl salicylate method includes such steps as loading 10 mL catalyst 15% CoAPO-5 in fixed-bed reactor, and preheating to 380 deg.C by introducing ammonia gas. Methyl salicylate was introduced into the reactor at a space velocity of 0.2. 0.2 h -1 The molar ratio of ammonia gas to methyl salicylate is 10:1. After the reaction at 380 ℃, the crude product is cooled and analyzed by a gas chromatograph to obtain the composition, the conversion rate of methyl salicylate is 99%, the selectivity of salicylnitrile is 82%, the purity of the salicylnitrile after distillation and purification reaches 97%, and the recovery rate is 95%.
Comparative example 4
A process for preparing salicylonitrile by continuous methyl salicylate method includes such steps as loading 10 mL alumina catalyst in fixed-bed reactor, introducing ammonia gas, and preheating to 380 deg.C. Methyl salicylate was introduced into the reactor at a space velocity of 0.2. 0.2 h -1 The molar ratio of ammonia gas to methyl salicylate is 10:1. After the reaction at 380 ℃, the crude product is cooled and analyzed by a gas chromatograph to obtain the composition, the conversion rate of methyl salicylate is 72%, the selectivity of salicylonitrile is 81%, the purity of the recrystallized and purified salicylnitrile reaches 92%, and the recovery rate is 55%.
Description of Performance results
From the above examples 1 to 6, it can be seen that the method provided by the application uses methyl salicylate and ammonia gas as raw materials, uses metal modified phosphorus-aluminum molecular sieve as catalyst, and has higher conversion rate, selectivity and yield in the reaction of synthesizing salicylonitrile by reacting at 320-420 ℃ and normal pressure.
Compared with the example 1, the conversion rate of methyl salicylate is reduced by 25%, the selectivity of target product salicylnitrile is reduced by 16%, the purity of salicylnitrile is reduced by 8% after distillation purification, and the recovery rate is reduced by 7% by using the conventional alumina catalyst, which shows that the catalyst has extremely strong catalytic activity by using the metal modified phosphorus-aluminum molecular sieve as the catalyst, improves the efficiency of acid catalytic conversion reaction from ammonification and dehydration of methyl salicylate to salicylnitrile, and has better process stability. The excellent catalytic performance of the metal modified aluminophosphate molecular sieve in the above reaction can be demonstrated.
Comparative example 2 compared with example 1, the phosphorus-aluminum molecular sieve catalyst is not modified by metal, and the conversion rate of methyl salicylate is reduced by 8%, the selectivity of target product salicylnitrile is reduced by 18%, the purity of salicylnitrile after distillation purification is reduced by 7%, and the recovery rate is reduced by 11%, which means that when the phosphorus-aluminum molecular sieve catalyst is not modified by metal, the acid site on the surface of the catalyst is few, the activity of the catalyst is poor, the reaction rate is reduced, and the conversion rate of methyl salicylate is further influenced.
Compared with the example 1, the modified metal content is 15%, the conversion rate of methyl salicylate is increased by 1%, but the selectivity of the target product salicylnitrile is reduced by 14%, which indicates that too many acid sites in the system are easy to cause hydrolysis-decarboxylation reaction of methyl salicylate and intermediate product salicylamide, so that water sample amide is hydrolyzed to generate salicylic acid, and then salicylic acid is decarboxylated to generate phenol, further the content of byproduct phenol is increased, and the selectivity of the product salicylnitrile is reduced.
Comparative example 4 compared with example 1, the target product was purified by using a conventional alumina catalyst and using a recrystallization method, it was found that the conversion of methyl salicylate was reduced by 26%, the selectivity of the target product salicylnitrile was reduced by 15%, the purity of salicylnitrile after distillation purification was reduced by 7%, and the recovery rate was only 55%, which was significantly lower than that of the distillation method. The application is illustrated by combining comparative example 1 that the two-stage reduced pressure distillation process not only improves the purity of the product, but also remarkably improves the recovery rate of the salicylonitrile product. Meanwhile, the continuous purification process of the salicylonitrile is realized, the process flow is simplified, and the production efficiency is improved. Thus, it can be demonstrated that the two-stage reduced pressure distillation process has excellent effects on continuous purification.
The present application is not limited to the above-mentioned embodiments, but is not limited to the above-mentioned embodiments, and any simple modification, equivalent changes and modification made to the above-mentioned embodiments according to the technical matters of the present application can be made by those skilled in the art without departing from the scope of the present application.
Claims (6)
1. A method for producing salicylonitrile by using methyl salicylate continuous method is characterized in that methyl salicylate and ammonia gas are introduced into a fixed bed reactor filled with a catalyst, and reacted under the conditions of a reaction temperature of 320-420 ℃ and normal pressure, and a crude product is purified to obtain a salicylonitrile product; the catalyst is a metal modified phosphorus-aluminum molecular sieve;
in the metal modified phosphorus-aluminum molecular sieve, the modified metal is one or more of Co, fe and Ni, the mole fraction of the modified metal in the total metal is 1-10%, and the total metal is the sum of the mole amounts of the modified metal and aluminum;
the liquid hourly space velocity of the methyl salicylate in the reaction process is 0.1-0.5 h -1 ；
The molar ratio of ammonia to methyl salicylate is 6-16:1;
the metal modified phosphorus aluminum molecular sieve is prepared according to the following method:
s1: placing pseudo-boehmite and deionized water in a reaction bottle, vigorously stirring at normal temperature for 20-40 min to obtain alumina sol, slowly dripping phosphoric acid into the alumina sol after dilution, vigorously stirring, keeping the temperature of a reaction system within 45 ℃, and continuously stirring for 20-40 min after dripping is completed to obtain uniformly dispersed aluminum phosphate sol;
s2: preparing a modified metal salt aqueous solution, dropwise adding the modified metal salt aqueous solution into the aluminum phosphate sol at room temperature, and stirring vigorously, and continuing stirring for 20-40 min after the dropwise adding is finished;
s3: slowly dropwise adding a template agent into the aluminum phosphate sol treated in the step S2, and vigorously stirring, wherein the temperature of a reaction system is kept within 30 ℃, and after the dropwise adding is finished, stirring is continued for 100-150 min to obtain an initial sol;
s4: aging the initial sol for 10-15 hours, transferring the initial sol into a high-pressure reaction kettle with polytetrafluoroethylene as a lining, raising the temperature to 170-200 ℃ at a speed of 5 ℃/min, crystallizing at constant temperature for 36-50 hours after the temperature is stable, cooling after crystallization, and washing the obtained sol with deionized water until the pH value of an eluate is neutral to obtain phosphorus-aluminum molecular sieve raw powder;
s5: drying the phosphorus-aluminum molecular sieve raw powder in a constant-temperature drying oven at 50-70 ℃ for 10-15 hours, and calcining at high temperature for 20-30 hours to obtain metal modified APO-5 molecular sieve solid powder;
s6: and tabletting, forming, crushing and screening the solid powder to obtain the solid catalyst with 20-40 meshes.
2. The method for producing salicylonitrile by using the methyl salicylate continuous method according to claim 1, wherein in the step S1, the concentration of the diluted phosphoric acid is 20-40%.
3. The method for producing salicylonitrile by using the methyl salicylate continuous method according to claim 1, wherein in the step S2, the concentration of the modified metal salt aqueous solution is 0.25-2.5 mol/L.
4. The method for producing salicyl nitrile by using the continuous methyl salicylate process according to claim 1, wherein in the step S3, the template agent is triethylamine.
5. The method for producing salicylonitrile by using the methyl salicylate continuous process according to claim 1, wherein in the step S5, the high-temperature calcination temperature is 500-700 ℃.
6. The method for producing salicylonitrile by using the methyl salicylate continuous method according to claim 1, wherein the purification process adopts a two-stage reduced pressure distillation process, the distillation temperature of the first-stage reduced pressure distillation is 18-30 ℃, and the pressure is 2000-4000 Pa; the distillation temperature of the second-stage reduced pressure distillation is 108-115 ℃ and the pressure is 350-450 Pa.
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