The Preparation Of Hierarchical Mesoporous Beta Zeolite And Desulfurization Performance

Beta zeolite is a very important kind of microporous zeolite and widely used in the chemical industry.But its small pore diameter limites its application in the macromolecular reaction.So the the design,synthesis and catalytic applications of hierarchical mesoporous beta zeolite have been drawn a great deal of attention.In this thesis,we prepared hierarchical structure beta zeolites by post-treatment method(also called "secondary mesopore method")and soft template method that characterized by XRD,SEM,FT-IR,NH3-TPD,XRF and N2 adsortion-desorption.The hierarchical mesoporous beta zeolites were applied in thiophene alkylation in order to overcome the diffusion limitation of macromolecule reactants and products and improve the catalytic performance of the catalysts.The main results were as follows:(1)Commercial beta zeolite was subjected to hydrothermal alkali treatment and the specific surface area and volume of mesopore were 216 m2 g-1 and 0.65 cm3·g-1 when treated with 0.1 mol·L-1 NaOH for 60 min at 650℃ When the hierarchical mesoporous beta zeolite was applied n under the conditions of reaction pressure 0.85 MPa,reaction temperature 160℃,reaction time 2 h and catalyst dosage 1 g,the thiophene conversion was 94.57%.The catalytic performance was recovered to some extent after the catalyst was regenerated.(2)The surfactant CTAB and ethanol assisted the synthesis of hierarchical mesoporous beta zeolite.Characterized by SEM and N2 adsortion-desorption,it was found that the addition of CTAB could affect the morphology of the molecular sieve while it generated mesopores.when the hierarchical mesoporous beta zeolite were applied in thiophene alkylation reaction and its catalytic performance was slightly better than that of commercial zeolite,the thiophene conversion of the best one can reach to 97.02%.The catalytic performance was recovered completely after the catalyst was regenerated.(3)The template-free beta zeolites were prepared by seed induction method under the conditions of crystallization temperature 120℃,crystallization time 96 h and seed addition amount of 5wt%.The synthetic template-free beta zeolites were treated with NaOH to obtain a little amount of mesopores,which had some effect on the adsorptive desulfurization and thiophene alkylation reaction.