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CN-122006793-A - Preparation method of iron cobalt oxide and Beta molecular sieve composite catalyst and application of iron cobalt oxide and Beta molecular sieve composite catalyst in lignin derivative vanillic acid demethoxy

CN122006793ACN 122006793 ACN122006793 ACN 122006793ACN-122006793-A

Abstract

The invention relates to the technical field of catalysts, in particular to a preparation method of an iron cobalt oxide and Beta molecular sieve composite catalyst and application thereof in removing methoxy groups of lignin derivative vanillic acid, wherein the prepared catalyst regulates and controls the reduction degree of cobalt species by introducing iron species with strong oxygen affinity so as to inhibit benzene ring hydrogenation side reaction, and meanwhile, the interaction of the iron and cobalt species enhances the acid sites of the catalyst, thereby being beneficial to adsorption and activation of substrates; the Co 0 /Fe 0.04 Co 0.96 O-Beta composite catalyst is used for the demethoxy catalytic reaction of vanillic acid, and reacts for 2 hours under the condition of 0.4MPaH 2 +0.4MPaCO 2 , the substrate conversion rate reaches 96.07%, the selectivity of p-hydroxybenzoic acid reaches 86.96%, and the target product yield is 83.54%.

Inventors

  • OUYANG XINPING
  • HUANG YUE
  • LI LIFENG
  • RUAN TAO

Assignees

  • 华南理工大学

Dates

Publication Date
20260512
Application Date
20260414

Claims (10)

  1. 1. The preparation method of the iron cobalt oxide and Beta molecular sieve composite catalyst is characterized by comprising the following steps of: s1, mixing ferric salt and cobalt salt in deionized water, dropwise adding citric acid solution, uniformly stirring, heating and evaporating to dryness to form foaming gel; S2, placing the foaming gel prepared in the step S1 in a muffle furnace, and calcining in an air atmosphere to obtain black iron cobalt oxide Fe X Co 1-X O; And S3, dispersing Fe X Co 1-X O and Beta molecular sieve of the iron-cobalt oxide in deionized water, uniformly stirring, drying, calcining in air, and carrying out reduction treatment under a hydrogen-containing argon mixed atmosphere to obtain the iron-cobalt oxide and Beta molecular sieve composite catalyst.
  2. 2. The preparation method of the iron-cobalt oxide-Beta molecular sieve composite catalyst according to claim 1, wherein iron salt and cobalt salt in S1 are ferric nitrate nonahydrate and cobalt nitrate hexahydrate respectively, the total concentration of the iron salt and the cobalt salt is 0.67mol/L, the concentration of the iron salt and the cobalt salt is lower than 0.67mol/L, the concentration of the iron salt and the cobalt salt is higher than 00.67mol/L, and the molar ratio of the iron to the cobalt is 1 (1-32).
  3. 3. The preparation method of the iron cobalt oxide and Beta molecular sieve composite catalyst according to claim 1, wherein citric acid in S1 is citric acid monohydrate, the concentration of the citric acid solution is 70-280 g/L, the molar quantity of the citric acid is 0.5-2 times of the total molar quantity of iron and cobalt, and the dropping speed of the citric acid solution is 2-4 mL/min.
  4. 4. The method for preparing the iron cobalt oxide and Beta molecular sieve composite catalyst according to claim 1, wherein the step S1 is heated and evaporated to dryness until the temperature for forming foaming gel is 60-140 ℃ for 2-6 hours.
  5. 5. The method for preparing the iron cobalt oxide and Beta molecular sieve composite catalyst according to claim 1, wherein the temperature of the calcination treatment in S1 is 300-550 ℃ and the time is 2-5 h, and the temperature rising rate of the calcination treatment is 3-10 ℃ per minute.
  6. 6. The preparation method of the composite catalyst of the iron cobalt oxide and the Beta molecular sieve according to claim 1, wherein in the step S3, the weight of Fe X Co 1-X O of the iron cobalt oxide accounts for 5-30% of the total weight of the composite catalyst of the iron cobalt oxide and the Beta molecular sieve, the silicon-aluminum ratio of the Beta molecular sieve is (25-50): 1, the stirring time of uniform stirring is 6-24 h, and the drying treatment method is that the drying is carried out at the temperature of 50-80 ℃ for 6-12 h.
  7. 7. The preparation method of the iron cobalt oxide and Beta molecular sieve composite catalyst according to claim 1, wherein in the step S3, grinding is performed before reduction treatment, the hydrogen volume ratio of a hydrogen-containing argon mixed atmosphere is 8%, the air flow speed of the hydrogen-containing argon mixed atmosphere is 40-150 mL/min, the temperature of the reduction treatment is 200-400 ℃, the time of the reduction treatment is 2-4 h, and the temperature rising speed of the reduction treatment is 3-10 ℃/min.
  8. 8. An application of the iron cobalt oxide and Beta molecular sieve composite catalyst prepared by the preparation method of the iron cobalt oxide and Beta molecular sieve composite catalyst according to any one of claims 1-7 in the demethoxy of lignin derivative vanillic acid, which is characterized in that the application method comprises the following steps: and (3) taking a solvent as a reaction medium in a high-pressure intermittent reaction kettle, and under the conditions of the temperature of 200-250 ℃ and the initial pressure of 0-1.2 MPa, performing demethoxy reaction on the lignin derivative vanillic acid under the action of a catalyst of the iron-cobalt oxide and Beta molecular sieve composite catalyst.
  9. 9. The application of the iron cobalt oxide and Beta molecular sieve composite catalyst according to claim 8, wherein the solvent is methanol, the ratio of the solvent to the lignin derivative vanillic acid is 20 (0.05-0.3) mL/g, and the weight ratio of the lignin derivative vanillic acid to the iron cobalt oxide to the Beta molecular sieve composite catalyst is (0.05-0.30).
  10. 10. The application of the iron cobalt oxide and Beta molecular sieve composite catalyst in removing methoxy of lignin derivative vanillic acid, which is characterized in that the initial hydrogen pressure of the initial pressure is 0-0.6 MPa, the initial carbon dioxide pressure is 0-0.6 MPa, the catalytic time of the catalyst is 1-4 h, and the catalytic temperature of the catalyst is 220 ℃.

Description

Preparation method of iron cobalt oxide and Beta molecular sieve composite catalyst and application of iron cobalt oxide and Beta molecular sieve composite catalyst in lignin derivative vanillic acid demethoxy Technical Field The invention relates to the technical field of catalysts, in particular to a preparation method of an iron cobalt oxide and Beta molecular sieve composite catalyst and application of the iron cobalt oxide and Beta molecular sieve composite catalyst in lignin derivative vanillic acid demethoxy. Background Under the dual-carbon background, biomass is used as the only renewable carbon source in the nature, and can effectively solve the problems of energy shortage and environmental pollution, so that the renewable biomass resource is used for replacing the traditional fossil energy to produce high-added-value chemicals, and the method has important significance. A series of derivatives of lignin obtained by depolymerization contain different numbers of methoxy groups, which need to be subjected to catalytic hydrodemethoxy to produce a single chemical. The technology of the invention aims at lignin-derived vanillic acid to prepare p-hydroxybenzoic acid by selective demethoxy, and the p-hydroxybenzoic acid is an important fine chemical raw material and is widely applied to the fields of food and cosmetic corrosion prevention and medical antibacterial. Problems in the process of the catalytic demethoxylation reaction of the vanillic acid include that the hydrogenation activity is too strong, which easily causes side reactions of benzene ring hydrogenation and phenolic hydroxyl removal, and the decarboxylation reaction of the vanillic acid easily occurs under the high-temperature catalytic condition. Therefore, it is necessary to develop a catalytic system for efficient selective demethoxy, which can selectively remove methoxy under milder conditions, and avoid excessive hydrogenation of benzene rings, removal of phenolic hydroxyl groups and decarboxylation side reactions, thereby realizing high-value utilization of lignin derivatives. The demethoxylation catalysts studied at present are mainly classified into noble metal type catalysts, transition metal type catalysts and molybdenum based catalysts. Noble metals Au and Ag have weaker hydrogenation activity, and can reduce the generation of benzene ring hydrogenation byproducts while removing methoxy groups, but the cost is higher. The oxygen affinity of the transition metals Fe and Co is favorable for adsorbing and activating methoxy, and the transition metals Fe and Co have rich resource content and low price. Although molybdenum-based catalysts have better demethoxylation properties, the reaction conditions generally require higher hydrogen pressures and the catalyst is too acidic and can easily lead to catalyst deactivation. Liu et al [ journal catalysis.2019,369,396-404] studied that Ag/TiO 2 catalyst catalyzes the demethoxylation of guaiacol at 300℃under 3MPa of hydrogen with phenol yields of about 45% and all phenols yields of about 64%. The FeOx/CeO 2 catalyst prepared by Li et al [ ACSCatal.2020,10,14624-14639] is used for the demethoxylation reaction of guaiacol, benzene is reacted under the hydrogen condition of 400 ℃ and 0.1MPa by adopting a fixed bed, the phenol yield is 56%, and the phenol yield is 87%. Bai et al [ ACSCatal.2016,6,6141-6145] catalyzed the demethoxy of vanillic acid and syringic acid by MoWBOx/AC and reacted under 400℃ C, H 2/CO2 atmosphere gave a yield of 71.6% of parahydroxybenzoic acid. Therefore, for lignin oxidative depolymerization derived vanillic acid, it is necessary to develop a catalyst system capable of selectively removing methoxy groups under milder conditions while retaining benzene rings and other functional groups. Disclosure of Invention Technical problem to be solved Aiming at the defects existing in the prior art, the invention provides a preparation method of an iron cobalt oxide and Beta molecular sieve composite catalyst and application thereof in the demethoxy of lignin derivative vanillic acid, and aims to ensure that the prepared iron cobalt oxide and Beta molecular sieve composite catalyst can selectively remove methoxy groups of lignin derivative vanillic acid under milder conditions, and avoid excessive hydrogenation of benzene rings, phenolic hydroxyl removal and decarboxylation side reactions, thereby realizing high-value utilization of lignin derivatives. Technical proposal In order to achieve the above purpose, the invention is realized by the following technical scheme: A preparation method of an iron cobalt oxide and Beta molecular sieve composite catalyst comprises the following steps: s1, mixing ferric salt and cobalt salt in deionized water, dropwise adding citric acid solution, uniformly stirring, heating and evaporating to dryness to form foaming gel; s2, placing the foaming gel prepared in the step S1 in a muffle furnace, and calcining in an air atmosphere to obtain black