Ni@Silicalite-1催化剂的制备及其催化CO_(2)加氢制CH_(4)与CO性能研究  

Research on preparation of Ni@Silicalite-1 catalyst and its catalytic performance in hydrogenation of CO_(2) to CH_(4) and CO

作　　者：赵玉[1] 张嘉兴 王明瑞 周阿娟 党飞雄 张光辉[1] 张安峰[1] 郭新闻[1] ZHAO Yu;ZHANG Jiaxing;WANG Mingrui;ZHOU Ajuan;DANG Feixiong;ZHANG Guanghui;ZHANG Anfeng;GUO Xinwen(State Key Laboratory of Fine Chemicals,Frontiers Science Center for Smart Materials,School of Chemical Engineering,Dalian University of Technology,Dalian 116024,Liaoning,China)

机构地区：[1]大连理工大学化工学院精细化工国家重点实验室,智能材料化工前沿科学中心,辽宁大连116024

出　　处：《低碳化学与化工》2023年第5期38-45,54,共9页Low-Carbon Chemistry and Chemical Engineering

基　　金：自治区重点研发任务专项(2022B01033);辽宁省“兴辽英才”计划(XLYC2008032);中央高校基本科研业务费(DUT22LAB602,DUT22LK24)。

摘　　要：采用沸石封装策略,合成了用于CO_(2)加氢反应的结构可控的Ni基催化剂,选择性获得CH_(4)或CO产物。采用SiO_(2)纳米球和Silicalite-1(S-1)分子筛作为载体,通过浸渍-再晶化的方法合成了一系列不同载量的Ni/X@S-1催化剂(X为SiO_(2)或S-1分子筛)。SEM结果表明,S-1分子筛作为载体时,其导向作用有利于后续再晶化形成S-1包覆层,在较低模板剂四丙基氢氧化铵(TPAOH)加入量(n(TPAOH)/n(SiO_(2))=0.1)的情况下即可实现S-1分子筛对Ni物种的封装,且封装的金属催化剂外表面平整,呈现规则的六边形板状结构。大分子液相加氢实验与能谱分析结果表明,Ni物种主要分布在S-1分子筛的内部。原位XRD分析和H_(2)-TPR结果表明,S-1分子筛限域封装Ni有效增强了NiO与载体间的相互作用,抑制了NiO向金属Ni的还原(Ni0),有利于构筑稳定的NiO相。CO_(2)加氢反应结果表明,不经H_(2)-预还原,主要活性相为NiO的催化剂(N-5.0%Ni/S-1@S-1)的CO选择性为96.4%;经过400℃H_(2)-预还原处理,活性相为Ni0的催化剂(R-5.0%Ni/S-1@S-1)的CH_(4)的选择性超过98.0%。NiO为生成CO的活性相,而Ni0为生成CH_(4)的活性相,通过调控催化剂预还原温度,可以有效控制活性Ni物种的价态组成,进而实现加氢产物CO与CH_(4)的选择性生成。Using zeolite-encapsulated strategy,the Ni-based catalysts with controllable structure was synthesized for the hydrogenation of CO_(2) to selectively obtain CH_(4) or CO.SiO_(2) nanospheres and silicalite-1(S-1)zeolite molecular sieves were used as carriers to synthesize a series of Ni/X@S-1 catalysts with various Ni loadings by impregnation-recrystallization method(X is SiO_(2) or S-1 zeolite molecular).SEM results show that S-1 molecular sieves as the carrier is conducive to the subsequent crystallization to form the S-1 cladding layer,and when the amount of template agent tetra-propylammonium hydroxide(TPAOH)added is low(n(TPAOH)/n(SiO_(2))=0.1),the Ni-species could be encapsulated by S-1 zeolite molecular sieves,and the outer surface of encapsulated metal catalysts is flat,exhibiting a regular hexagonal plate morphology.Experimental results of macromolecules liquid phase hydrogenation and energy spectrum analysis reveal that the Ni species are mainly distributed inside S-1 zeolite molecular sieves.The results of in situ XRD and H_(2)-TPR indicate that the encapsulation of S-1 zeolite molecular sieves effectively enhances the interaction between NiO and carriers,inhibit the reduction of NiO towards metallic Ni(Ni0),which is beneficial to stable NiO phases.The results of CO_(2) hydrogenation indicate that without H_(2) pre-reduction,the CO selectivity of the main active phase of NiO(N-5.0%Ni/S-1@S-1)is 96.4%.After 400℃H_(2) prereduction,the CH_(4) selectivity of the main active phase of Ni0(R-5.0%Ni/S-1@S-1)is over 98.0%.NiO is the active phase for the formation of CO,while Ni0 is the active phase for the formation of CH_(4).The valence composition of active Ni species can be well controlled by tuning pre-reduction temperature to realize the selective generation of hydrogenation products CO and CH_(4).

关 键 词：CO_(2)加氢 NI基催化剂 分子筛封装 原位XRD 活性结构 

分 类 号：TQ426[化学工程]