两步晶化合成ZSM-22分子筛及其临氢异构反应性能

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中文摘要：采用两步晶化法,通过调节加入铝源的时间合成了一系列ZSM-22分子筛,并对其酸性位点的分布进行调控.采用XRD、SEM、N2吸附/脱附、NH3-TPD、FTIR、Py-IR、ICP、TEM-EDS等表征方法对其物相、形貌、织构性质、酸性和元素进行表征分析.结果表明,第二步晶化时,加入铝源,在模板剂诱导作用下,促使第一步晶化后高硅ZSM-22表面未晶化的无定形硅酸盐原位合成了 ZSM-22分子筛,使高硅ZSM-22表面生长一层低硅铝比ZSM-22分子筛,从而使分子筛的酸性位点发生改变.制备了 Pt负载双功能催化剂,研究其正十二烷的临氢异构化反应性能.结果表明,两步晶化ZSM-22分子筛可以抑制微孔内的裂化反应,获得更高异构产物选择性,其中S6-C在330℃时,转化率为89.3％,选择性89.4％,产率79.8％.通过两步晶化方式合成的ZSM-22分子筛,活性位点更多地位于分子筛的外表面和孔口附近,进而改变其异构体产物的分布,降低支链位于碳链端位异构体的比例,更倾向于生成支链位于碳链中间位置的异构体,S12-C的2-甲基十一烷分布比例比常规ZSM-22降低10％左右.

外文标题：Synthesis of ZSM-22 molecular sieve by two-step crystallization and its hydroisomerization performance

外文摘要：A series of ZSM-22 molecular sieves were synthesized by adjusting the time of adding aluminum source by two-step crystallization method,and the distribution of acid sites was regulated.XRD,SEM,N2adsorption/desorption,NH3-TPD,FTIR,Py-IR,ICP,TEM-EDS and other characterization methods were used to characterize the phase,morphology,texture properties,acidity and element.The results show that ZSM-22 molecular sieve is synthesized in situ from amorphous silicate which is not crystallized on the surface of high silicon ZSM-22 after the first step of crystallization with the addition of aluminum source under the induction of template agent,and a layer of ZSM-22 molecular sieve with low Si/Al ratio is grown on the surface of high silicon ZSM-22,thus changing the acid site of the molecular sieve.The Pt-supported bifunctional catalyst was prepared and its hydroisomerization performance of n-dodecane was studied.The results show that the two-step crystallization of ZSM-22 can inhibit the cracking reaction in micropores and obtain higher isomerization selectivity.The conversion of S6-C at 330℃ is 89.3％,the selectivity is 89.4％,and the yield is 79.8％.ZSM-22 molecular sieve synthesized by two-step crystallization had more active sites located on the outer surface and near the pore mouth of the molecular sieve,thus changing the distribution of its isomers,reducing the proportion of isomers with branch chains at the end of the carbon chain,and preferring to generate isomers with branch chains at the middle of the carbon chain.The distribution ratio of 2-methylundecane in S12-C is about 10％lower than that of conventional ZSM-22.

外文关键词：

molecular sievecatalysttwo-step crystallizationhydroisomerizationn-dodecane

作者：

王树振、王玉婷、马梦茜、张巍、向江南、鲁海莹、王琰、范彬彬、郑家军、代卫炯、李瑞丰

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作者单位：

太原理工大学化学工程与技术学院,山西太原 030024

关键词：

分子筛催化剂两步晶化临氢异构化正十二烷

基金：

国家重点研发计划项目山西省基础研究计划-自然科学研究面上项目国家自然科学基金项目国家自然科学基金项目国家自然科学基金项目国家自然科学基金项目国家自然科学基金青年基金项目中国石油化工股份有限公司资助项目中国石油化工股份有限公司资助项目中央引导地方科技发展资金项目

项目编号：

2020YFB0606405202203021221055U21B2010022378293223021432237828622302143121014-2122027YDZJSX2021A014

出版年：

2024

DOI：

10.11949/0438-1157.20240307

化工学报

中国化工学会化学工业出版社

化工学报

CSTPCD北大核心

影响因子：1.26

ISSN：0438-1157

年,卷(期)：2024.75(9)