The Synthesis And Modification Of Molecular Sieves With ZSM-35and Study On Performance Of Skeletal Isomerization Of1-butene

Zeolite molecular sieve as acid catalysts are widely used in petroleum chemical industry,for example, Y type molecular sieve used for fluidized catalytic cracking and hydrogenationcracking；ZSM-5zeolite used in xylene isomerization, hydrogenation dewaxing, alkylationand aromatization;Molecular sieve ZSM-35for butene skeleton isomerization and butenecracking;Based on the comparison of the main channel for ten yuan ring one dimensionalstructure of ZSM-35, SPAO-11, ZSM-22, ZSM-23on the basis of molecular sieves used incatalytic butene skeleton isomerization reaction;Of ZSM-35the influence factors of molecularsieve synthesis and modification methods of detailed study, at the same time by using XRD,NH3TPD, SEM characterization methods are analyzed, using the device for the evaluation offixed bed micro reactor is butene skeleton isomerization reaction performance test.By hydrothermal synthesis method to synthesize the one dimensional porous ten yuanring ZSM-35, SPAO-11, ZSM-22, ZSM-23molecular sieve, and compared its catalyticproperties are butene isomerization reaction.Four kinds of catalyst can be used in catalysis isbutene skeleton isomerization reaction, including molecular sieve ZSM-35shows excellentcatalytic performance and at atmospheric pressure, reaction temperature400℃, under thecondition of airspeed for7h-1, isobutene selectivity up to86%.Using tetrahydrofuran, ethylenediamine, pyrrolidine synthesis ZSM-35molecular sieveas template agent, XRD, SEM, biological microscope analysis.Tetrahydrofuran as templateagent thereof not successful synthesis of molecular sieve ZSM-35, ethylenediamineAs the template agent of synthetic products of magnesium alkali zeolite facies, but have amordenite.Pyrrolidine as template agent for molecular sieve ZSM-35pure phase synthesis,and retains the good crystallinity, as the best template agent.Pyrrolidine as the template agentof raw materials is studied in silica alumina ratio and the effect of basicity of the molecularsieve synthesis ZSM-35, found that reduce silica alumina ratio, increase alkalinity of reactionmaterials to improve the purity of product.Also studied the pyrrolidine as the template agentsynthesis of molecular sieve ZSM-35and transition temperature, crystallization time foundthat change extended crystallization temperature, crystallization time product can effectivelyreduce the content of mordenite.In order to optimize the ZSM-35molecular sieve catalytic properties, this paper attemptsto further modification of the molecular sieve ZSM-35,550℃,600℃,650℃temperaturesteam processing, NH3-TPD results show that the treatment can reduce the amount of B acid,high temperature steam treatment can cause Al-OH-Si bridge hydroxyl removal, theevaluation results also reflect the high temperature steam after processing are buteneconversion rate from54%to54%, this shows off excessive aluminum can lead to excessivenon-framework aluminum species blocking channel, skeleton and even collapse.Hydrochloricacid, citric acid, oxalic acid, nitric acid modified molecular sieve ZSM-35, the results show that modified by oxalic acid and citric acid, molecular sieve ZSM-35selectivity increasedfrom86%to91%, yield increased from41%to41%, and can maintain good stability, achievethe goal of the modification.Since then, looked at the reaction temperature is350℃,400℃,450℃of citric acid on the modified molecular sieve ZSM-35are butene skeletonisomerization performance, the influence of the reaction temperature is400℃when the bestcatalytic performance.Examines the reaction space velocity of3.5h-1,7h-1,14h-1is of oxalicacid on the modified molecular sieve ZSM-35butene skeleton isomerization reaction, theeffect of the airspeed for7h-1when the best catalytic performance.