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CN-122006790-A - Preparation method of alkali treatment-ytterbium ion exchange ZSM-5 molecular sieve catalyst and application of catalyst in preparation of phenol by dealkylation of biomass-derived alkylphenols

CN122006790ACN 122006790 ACN122006790 ACN 122006790ACN-122006790-A

Abstract

The invention relates to the technical field of molecular sieve catalysts, in particular to a preparation method of an alkali treatment-ytterbium ion exchange ZSM-5 molecular sieve catalyst and application thereof in preparing phenol by dealkylation of biomass derived alkylphenols, wherein a stepped preparation route of a hierarchical pore-ammonium chloride three-time exchange recovery hydrogen-ytterbium ion exchange acid regulation is constructed by the cooperation of sodium hydroxide/tetrapropylammonium hydroxide and alkali treatment, the definition of process steps and the accurate control of parameters are realized, the route not only maintains the MFI topological structure of a zeolite molecular sieve, but also forms a micro-mesoporous hierarchical structure by alkali treatment, and the mass transfer efficiency is remarkably improved; and the Bronsted/Lewis acid position proportion regulation of the Bronsted/Lewis acid position is matched with the ytterbium ion exchange to form a Lewis acid enrichment surface, a structural basis is provided for efficient catalysis, and unified process parameters are set at key nodes such as 550 ℃ calcination, 80 ℃ stirring and the like in the preparation process, so that the batch stability and the feasibility of amplification implementation are ensured.

Inventors

  • OUYANG XINPING
  • HE WENTING
  • YAO SHIHUA
  • LI LIFENG

Assignees

  • 华南理工大学

Dates

Publication Date
20260512
Application Date
20260414

Claims (6)

  1. 1. The preparation method of the alkali treatment-ytterbium ion exchange ZSM-5 molecular sieve catalyst is characterized by comprising the following steps: s1, preprocessing a ZSM-5-P molecular sieve to obtain a preprocessed ZSM-5-P molecular sieve; s2, carrying out alkali treatment on the pretreated ZSM-5-P molecular sieve to construct a classification hole, and obtaining the ZSM-5 molecular sieve with the classification hole; S3, performing ammonium chloride ion exchange and roasting on the hierarchical pore ZSM-5 molecular sieve in the S2 to recover a hydrogen type, and obtaining the hydrogen type hierarchical pore molecular sieve ZSM-5-4; S4, performing ytterbium ion exchange modification treatment on the hydrogen type hierarchical pore molecular sieve ZSM-5-4, and obtaining the alkali treatment-ytterbium ion exchange ZSM-5 molecular sieve catalyst.
  2. 2. The method for preparing the alkali treatment-ytterbium ion exchange ZSM-5 molecular sieve catalyst according to claim 1, wherein the pretreatment method in S1 is as follows: And calcining the ZSM-5-P molecular sieve in an air atmosphere at 550 ℃ for 5.5 hours to obtain the pretreated ZSM-5-P molecular sieve.
  3. 3. The method for preparing the alkali treatment-ytterbium ion exchange ZSM-5 molecular sieve catalyst according to claim 1, wherein the method for constructing the hierarchical pore by alkali treatment in S2 is as follows: s2.1, mixing a sodium hydroxide solution and a tetrapropylammonium hydroxide solution to prepare an alkali solution with the total hydroxyl concentration of 0.2 mol/L; S2.2, weighing 3-6 g of pretreated ZSM-5-P molecular sieve, pouring the pretreated ZSM-5-P molecular sieve into 90-180 mL of alkali solution, stirring the mixture at 80 ℃ for 4 hours, immediately transferring the mixture into ice water for quenching, centrifugally separating out solid components, washing the solid components to be neutral by deionized water, drying the solid components at 60 ℃ for 12 hours, and finally calcining the solid components at 550 ℃ for 5.5 hours in an air atmosphere to obtain the hierarchical pore ZSM-5 molecular sieve.
  4. 4. The method for preparing the alkali treatment-ytterbium ion exchange ZSM-5 molecular sieve catalyst according to claim 1, wherein the method for carrying out the ion exchange and roasting recovery hydrogen treatment of ammonium chloride in S3 is as follows: Immersing the hierarchical pore ZSM-5 molecular sieve in the S2 into 90-180 mL of ammonium chloride solution with the concentration of 0.5mol/L, carrying out ion exchange under the conditions of 80 ℃ and 300r/min, separating and exchanging again after each exchange, and calcining for 5.5h in the air atmosphere at 550 ℃ after three ion exchange-washing cycles, thus obtaining the hydrogen hierarchical pore molecular sieve ZSM-5-4.
  5. 5. The method for preparing the alkali treatment-ytterbium ion exchange ZSM-5 molecular sieve catalyst according to claim 1, wherein the method for modifying ytterbium ion exchange in S4 is as follows: Adding 1-2 g of hydrogen type hierarchical pore molecular sieve ZSM-5-4 and calculated ytterbium nitrate pentahydrate into 15-30 mL of deionized water, mixing, stirring at room temperature for 24h, drying at 80 ℃ for 12h, and finally calcining at 550 ℃ in air atmosphere for 5.5h to obtain the alkali treatment-ytterbium ion exchange ZSM-5 molecular sieve catalyst, wherein the ytterbium element accounts for 0.52-13.0% of the total weight of the hydrogen type hierarchical pore molecular sieve ZSM-5-4.
  6. 6. Use of an alkali treated-ytterbium ion exchanged ZSM-5 molecular sieve catalyst prepared according to the method of preparation of any of claims 1-5 in the dealkylation of biomass derived alkylphenols to phenol, characterized in that the method of use is: Placing 0.5g of alkali treatment-ytterbium ion exchange ZSM-5 molecular sieve catalyst with the mesh number of 40-80 in the middle section of a reactor, fixing quartz cotton, introducing nitrogen at the flow rate of 15mL/min, pumping mixed liquid of 4-n-propyl phenol and water in biomass derived alkylphenols by a high-pressure sample inlet pump at the molar ratio of 1:6, wherein the feeding flow rate is 0.017-0.050 mL/min, maintaining 453K in a preheating section of the fixed bed reactor, and maintaining 573-673K in a reaction section for dealkylation reaction.

Description

Preparation method of alkali treatment-ytterbium ion exchange ZSM-5 molecular sieve catalyst and application of catalyst in preparation of phenol by dealkylation of biomass-derived alkylphenols Technical Field The invention relates to the technical field of molecular sieve catalysts, in particular to a preparation method of an alkali treatment-ytterbium ion exchange ZSM-5 molecular sieve catalyst and application of the catalyst in preparation of phenol by dealkylation of biomass-derived alkylphenols. Background Fossil resources have long been an important source of human chemical raw materials and energy, but their non-renewable nature and the resources and environmental pressures resulting therefrom are increasingly prominent. Biomass, which is the only renewable organic carbon resource, has the advantages of abundant reserves, wide sources, sustainable utilization and the like, and has become an important raw material for preparing high-added-value chemicals by replacing part of fossil resources. Lignin is the only component rich in aromatic structural units in natural biomass, so that lignin is considered as an important renewable resource for preparing phenols and other aromatic chemicals, and has important research significance and application prospect in the field of biomass high-value utilization. Lignin can be subjected to depolymerization, hydrodeoxygenation and other conversion processes to generate a series of monophenols, wherein alkylphenols are important intermediate products. Lignin-derived alkylphenols represented by 4-n-propylphenol can be further used for preparing basic aromatic chemicals such as phenol by dealkylation. Phenol is an important basic organic chemical raw material and is widely applied to the fields of resin, plastics, synthetic fibers, medicines, pesticides, coatings and the like. Currently, industrial phenol production still mainly depends on fossil resources. Therefore, the method for dealkylating the lignin-derived alkylphenol as a substrate to prepare phenol provides an attractive technical route for green preparation of phenol, and is also an important research direction for directional conversion and high-value utilization of lignin. Currently, for alkylphenol dealkylation, studies have been directed to a variety of catalytic systems including basic oxides, fluorine modified solid acids, amorphous silica alumina materials, and zeolite molecular sieves, among others. Milnes et al [ J.Appl. chem. Biotechnol.,1971,21:287-296] have conducted earlier related studies on the dealkylation of alkylphenols, yoshikawa et al [ Catalyst today,2020,347:110-114], huang et al [ ACSCATALYSIS,2018,8:11184-11190], and Zhang et al [ ChineseJournalofCatalysis,2018,39:1445-1452], have also conducted studies on the dealkylation of phenols, respectively, from different catalytic systems. Compared with other catalytic materials, the zeolite molecular sieve has a regular pore structure, a higher specific surface area and rich acid sites, and has better application potential in alkylphenol dealkylation reaction. Among various acidic zeolites, ZSM-5 zeolite has an MFI topological structure, proper pore channel size, good thermal stability and good hydrothermal stability, and shows good catalytic activity and phenol selectivity in alkylphenol dealkylation, so that the ZSM-5 zeolite becomes a type of catalytic material which is most concerned in the research of the reaction. Verboekend et al [ Greenchemistry 2016,18:297-306] showed that acidic zeolites were able to catalyze the dealkylation of alkylphenols to phenol and lower olefins, and Liao et al [ ACSCATALYSIS,2018,8:7861-7878] further systematically compared the performance of different acidic zeolites in dealkylation of 4-n-propylphenol, indicating a better balance of ZSM-5 activity, selectivity and shape selectivity. Although ZSM-5 shows better catalytic performance in alkyl phenol dealkylation, the traditional microporous ZSM-5 still has the problems of obvious diffusion limitation, easy retention of reaction intermediates and products in pore channels, easy carbon deposition deactivation and the like, thereby reducing accessibility of acid sites and affecting the activity and stability of the catalyst. In view of the above problems, there have been studies on attempts to construct hierarchical pore ZSM-5 by alkali treatment or desilication to shorten the diffusion path and alleviate the pore blocking. Liao et al [ ACSSustainableChemistry & Engineering,2020,8:8713-8722] reported that classification of ZSM-5 was effective in improving product diffusion and increasing catalyst stability, while indicating that increasing the density and strength of Lewis acid sites helped to further enhance dealkylation performance. Apart from pore structure regulation, the acid site distribution, especially the synergy of the Bronsted acid site and the Lewis acid site, is also considered to be a key factor affecting the dealkylation activity and selectivity