Geometric effect promoted hydrotalcites catalysts towards aldol condensation reaction  

几何效应促进水滑石催化剂实现对羟醛缩合反应性能提升

作　　者：Huimin Wang Weihan Bing Chunyuan Chen Yusen Yang Ming Xu Lifang Chen Lei Zheng Xiaolin Li Xin Zhang Jianjun Yin Min Wei 王慧敏;邴威瀚;陈春源;杨宇森;徐明;陈利芳;郑雷;李晓林;张欣;殷建军;卫敏(北京化工大学化工资源有效利用国家重点实验室,北京100029;中国天辰工程公司技术研发中心,天津300400;中国科学院高能物理研究所,北京100049;中国石油化工股份有限公司北京化工研究院,北京100013)

机构地区：[1]State Key Laboratory of Chemical Resource Engineering,Beijing Advanced Innovation Center for Soft Matter Science and Engineering,Beijing University of Chemical Technology,Beijing 100029,China [2]China Tianchen Engineering Corporation Technology Research and Development Center,Tianjin 300400,China [3]Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China [4]SINOPEC Beijing Research Institute of Chemical Industry,Beijing 100013,China

出　　处：《Chinese Journal of Catalysis》2020年第8期1279-1287,共9页催化学报（英文）

基　　金：国家自然科学基金(21871021,21521005,91741104);国家重点研发计划(2017YFA0206804);中央高校基本科研业务费专项资金(buctylkxj01,XK1802-6).

摘　　要：In solid basic catalysis field,how to achieve optimized activity and desired stability through elaborate control over basic site properties remains a challenge.In this work,taking advantage of the structure memory effect of layered double hydroxides(LDHs),rehydrated Ca4 Al1-x Gax-LDHs and Ca4 Al1-x Inx-LDHs catalysts were prepared and applied in aldol condensation reaction that isobutyraldehyde(IBD)reacts with formaldehyde(FA)to obtain hydroxypivalaldehyde(HPA).Notably,the resulting re-Ca4 Al0.90Ga0.10-LDHs exhibits an extraordinarily-high catalytic activity(HPA yield:72%),which is to our best knowledge the highest level in this reaction.The weak Br?nsted basic site,7-coordinated Ca-OH group,which serves as an active site,catalyzes the condensation process and promotes the product desorption.Studies on structure-property correlations demonstrate that Ga as a structural promoter induces a moderate expansion of the laminate lattice,which results in a significant increase in the concentration of weak basic sites in re-Ca4Al0.90Ga0.10-LDHs,accounting for its high catalytic activity.This work illuminates that geometric structure of basic active sites can be tuned via introducing catalyst additive,which leads to a largely improved performance of hydrotalcite solid basic catalysts towards aldol condensation reaction.近年来,绿色发展观念深入人心.与液体碱相比,固体碱催化剂由于其环境友好、腐蚀性小、易于回收等优点引起了科研工作者的广泛关注.但是,在固体碱催化领域,如何对碱性位点进行调控从而使羟醛缩合反应获得优异性能仍然是一个很大挑战.甲醛和异丁醛反应生成的产物羟基新戊醛是精细化工合成中一类非常重要的有机中间体,广泛应用于药物、润滑油、聚酯树脂等化工产品生产.目前,应用于该反应的固体碱催化剂催化活性较低,性能有待进一步提升.因此,设计一类结构可调、性能优异的固体碱催化剂材料迫在眉睫.本文利用水滑石材料结构特有的记忆效应制备了一系列掺杂镓、铟的钙铝水滑石催化剂,并将其应用于甲醛与异丁醛缩合生成羟基新戊醛反应,并探讨了不同离子半径的元素掺杂对钙铝水滑石结构产生的影响和作用.结果表明,复原后的re-Ca4Al0.90Ga0.10-LDH对羟基新戊醛的生成表现出优异的性能(HPA产率为72%),达到固体碱催化剂催化该反应的最高水平,甚至与液体碱催化剂水平相当.通过氘代氯仿原位红外光谱对催化剂的活性位点进行表征,结果证明掺入镓之后使弱碱性位点的相对浓度增加,而掺入铟后使弱碱性位点的相对浓度减小.进而将弱碱性位点的数量和中强碱性位点的数量与催化性能结果进行构效关联,证明了该反应中的活性中心为弱碱性位点(7配位Ca-OH).该弱碱性位点不仅促进了产物羟基新戊醛的脱附,还提高了反应的活性和选择性,使得羟基新戊醛的产率大大提升.通过EXAFS手段对催化剂的精细结构进行表征,证明了掺入镓和铟后,钙铝水滑石晶格发生了膨胀,Ca-O键长增加.其中,掺杂铟元素使得铟与水滑石层间羟基形成额外的In-OH化学键,从而使七配位的Ca-OH位点浓度降低.通过XPS和DFT计算证明了掺入镓和铟后催化剂的碱性强度没有发生变化,�

关 键 词：Solid basic catalyst Geometric structure Structural promoter Aldol condensation Reconstructed hydrotalcite material 

分 类 号：TQ224.1[化学工程—有机化工] TQ426