Preparation,Characterization Of Hierarchical Pore ZSM-5 Molecular Sieve And Application In Reaction Of Tertiary Butylation Of Phenol

Microporous,mesoporous and macroporous materials have great adjustability in morphology,composition and structure,so they are widely used in petrochemical industry,adsorption separation,biosensing and other scientific and technological fields.As we all know,silicon-aluminum materials with pore structure as a good solid acid catalyst have a wide range of applications in petrochemical industry,medicine and other fields.However,microporous,mesoporous,and macroporous materials have their own advantages and disadvantages,and there is an urgent need to prepare new composite porous materials that combine the advantages of various pores.The multi-stage pore material with pore composite has many types of pore size,good hydrothermal stability,excellent shape-selective catalytic performance and strong acidity,and also has a large pore volume,high specific surface area,and small Advantages such as mass transfer resistance.However,the current common problems in preparing multi-stage pore molecular sieves are long preparation time and high manufacturing cost.This paper mainly studies the preparation,characterization and application of multi-level porous materials.Using Fourier infrared(FT-IR),X-ray powder diffraction(XRD),physical adsorption,scanning electron microscopy(SEM),transmission electron microscopy(TEM),NH3-TPD and other characterization methods to structure and morphology of multi-level porous materials,Physical parameters,etc.The research progress of microporous,mesoporous and macroporous materials are described respectively,and their respective advantages and disadvantages,as well as the characteristics and research status of multi-level porous materials are introduced.The mesoporous porogen citric acid was added to the pre-crystallized silica-alumina sol at different times to prepare microporous-mesoporous ZSM-5 multi-stage porous materials,which were applied to the phenol tert-butylation reaction to investigate the catalytic performance and screened by conditions The conversion rate of NM-ZSM-5-16h multi-stage porous material to phenol is as high as 87.5%,of which the selectivity to 4-tert-butylphenol reaches 62.7%,and that to 2,4-di-tert-butylbenzene The selectivity is 21.6%.By introducing macropores into the microporous-mesoporous composite material,a multi-level porous material with microporous-mesoporous-macropores is prepared.In addition,the specific preparation method of the hard template-carboxy polystyrene microsphere emulsion is introduced in detail.The macropore is introduced into the micropore-mesopore by using the carboxypolystyrene microsphere emulsion as the macropore hard template agent.After a series of conditions optimization,polydiallyl dimethyl ammonium chloride(PDDA)with different dilution ratios was used to modify the carboxy polystyrene microspheres to prepare different series of multi-stage porous materials,using FT-IR,Characterized by XRD,physical adsorption.The effects of PDDA with different dilution ratios on the pore formation of multi-stage porous molecular sieve materials were initially explored.The carboxyl polystyrene microsphere emulsion was dried into powder and used as a macroporous pore-forming agent.The microporous-mesoporous-macroporous composite multi-level pore material was prepared by steam crystallization method.Through a series of characterization,pore wall crystals were obtained A more complete microporous-mesoporous-macroporous composite multi-level porous material.The result of phenol tert-butylation reaction showed that the conversion rate of H-ZSM-5-12h multi-stage molecular sieve to phenol reached 84.5%,and the selectivity of the reaction product 4-tert-butylphenol reached 67.6%.Using polydiallyl dimethyl ammonium chloride(PDDA)diluted twice,the carboxy polystyrene microsphere emulsion is modified and dried into powder,so that the monodispersed carboxy polystyrene microspheres are gathered together as The hard template successfully prepared a multi-stage pore molecular sieve.Using the same characterization method for characterization,through the analysis of the phenol tert-butylation reaction results,the conversion rate of the sample HP-ZSM-5-12h to phenol reached 92.3%,and the selectivity of the reaction product 4-tert-butylphenol reached 75.4%,with good macromolecular selectivity.This paper elaborated on the preparation conditions and methods of multi-level porous materials,and through a series of characterization methods to characterize the morphology,structure,characteristics and catalytic performance of the materials,for the preparation and industrial application of multi-level porous silicon aluminum materials Provide a certain reference basis.