Zhang Yaowen, Wei Shaoping, Lin Yanjun, Fan Guoli, Li Feng
State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, No.15, Beisanhuan East Road, Beijing 100029, China.
ACS Omega. 2018 Oct 8;3(10):12778-12787. doi: 10.1021/acsomega.8b02114. eCollection 2018 Oct 31.
Layered double hydroxides (LDHs), a category of two-dimensional nanostructured layered materials, can be employed widely as supports, catalyst precursors, and actual catalysts in a variety of heterogeneous catalytic reactions. In this work, we reported a series of Fe-containing LDHs-supported Pt-based catalysts for base-free selective hydrogenation of cinnamaldehyde into cinnamyl alcohol. It was revealed that their catalytic performances were closely correlated to the compositions of LDH supports. Especially, highly selective hydrogenation of cinnamaldehyde could be achieved over the Fe(II)-Fe(III)-LDH (green rust, FeFe-LDH) supported Pt catalyst, with a high cinnamyl alcohol selectivity of about 92% at a conversion of 90% after a reaction of 2 h, superior to other Fe(III)-containing LDHs (e.g., NiFe-LDH, CoFe-LDH, and ZnFe-LDH) supported Pt ones. It was demonstrated that the high catalytic efficiency of Pt/FeFe-LDH mainly originated from highly electron-rich character of metallic Pt species and the presence of surface reductive Fe species, thereby being helpful for the chemisorption and activation of carbonyl group in cinnamaldehyde. Moreover, strong interactions between green rust matrix and metallic Pt species could stabilize the surface Pt nanoparticles, thereby inhibiting the metal leaching during the above reaction. The present study illustrates the validity of support control in supported Pt catalysts via tuning the compositions of LDHs, and thus the electronic structure of active metal sites and catalytic performance in the selective hydrogenation of cinnamaldehyde.
层状双氢氧化物（LDHs）是一类二维纳米结构的层状材料，在各种多相催化反应中可广泛用作载体、催化剂前体和实际催化剂。在本工作中，我们报道了一系列含Fe的LDHs负载的Pt基催化剂，用于肉桂醛无碱选择性加氢制备肉桂醇。结果表明，它们的催化性能与LDH载体的组成密切相关。特别是，在Fe（II）-Fe（III）-LDH（绿锈，FeFe-LDH）负载的Pt催化剂上可实现肉桂醛的高选择性加氢，在反应2 h后转化率为90%时，肉桂醇选择性高达约92%，优于其他含Fe（III）的LDHs（如NiFe-LDH、CoFe-LDH和ZnFe-LDH）负载的Pt催化剂。结果表明，Pt/FeFe-LDH的高催化效率主要源于金属Pt物种的高富电子特性和表面还原态Fe物种的存在，从而有利于肉桂醛中羰基的化学吸附和活化。此外，绿锈基体与金属Pt物种之间的强相互作用可稳定表面Pt纳米颗粒，从而抑制上述反应过程中的金属浸出。本研究通过调节LDHs的组成，说明了负载型Pt催化剂中载体控制的有效性，进而说明了活性金属位点的电子结构和肉桂醛选择性加氢中的催化性能。
