Preparation Of Hierarchical Porous Silica-aluminum Molecular Sieves By Hard And Soft Template

As is known to all,ZSM-5 microporous molecular sieve is one of the most important and widely used catalysts in petroleum refining and petrochemical industry due to its excellent acidity and good shape selection.In recent years with increasing oil chemical reaction of polymer and liquid phase reaction,traditional zeolite materials due to its small hole size(less than 2 nm),diffusion resistance is bigger,a lot of reactant and intermediate molecules are too large to enter the zeolite pore,cannot achieve the desired catalytic effect,make the practical application of micro Kong Feishi molecular sieve is restricted.If the strong acidity of ZSM-5 micropore is combined with the good mass transfer ability of mesopore or macropore to prepare a zeolite with multistage pore structure,give full play to the advantages of various pore channels and improve the disadvantages of single-stage pore channels,it will be an important for the petrochemical field.In this paper,polydiallyl dimethylammonium chloride,polyacrylic acid and polyurethane foam,which are environmentally friendly and cheap,were selected as templates to prepare multiporous silica-aluminum materials,and the catalytic activity of phenol tert-butyl reaction was investigated.In this paper,the research progress of microporous,mesoporous and macroporous materials is described,and their advantages and disadvantages are introduced,as well as the characteristics and research status of multiporous materials.To advance different crystallization time of adding different quality of soft template silica alumina sol agent poly diallyl dimethyl ammonium chloride,preparation of PDDA-N-ZSM-5multistage aperture sialic material,USES the Fourier infrared and X-ray powder diffraction,adsorption,scanning electron microscopy characterization methods,such physical parameters were characterized.Through the pre-crystallization of silica alumina sol at different time,adding different quality of template agent polyacrylic acid,the multiporous silica alumina material was successfully prepared under two different conditions.By characterizing the pore structure and morphology,tert-butylation reaction of phenol was used to study the catalytic performance,and it was found that the phenol conversion rate was the highest when the dosage of template was 1.5 m L for 0 h pre-crystallization of si-Al sol.In addition,polyurethane foam as hard template agent,preparation of microporous-mesoporous-macroporous structure materials are also introduced in detail.After a series of optimization conditions,the polyurethane foam was modified by immersing in silica alumina sol at different time of pre-crystallization to prepare different series of ZSM-5 multiporous molecular sieve materials.According to the tert-butyl reaction of phenol,when the template agent is polyurethane foam,the transformation of phenol tert-butyl group to silica aluminum sol changes at different time of precrystallization.The conversion rate of phenol to PAC-N-ZSM-5(0h)multiporous material is up to 95%.