Platinum catalysed aerobic selective oxidation of cinnamaldehyde to cinnamic acid
Platinum catalysed aerobic selective oxidation of cinnamaldehyde to cinnamic acid
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DOI：
10.1016/j.cattod.2018.02.052
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发表时间：
2019-08-01
期刊：
影响因子：
5.3
通讯作者：
Lee, Adam F.
中科院分区：
文献类型：
--
作者：
Durndell, Lee J.;Cucuzzella, Costanza;Lee, Adam F.
烯丙醛的有氧选择性氧化为制备不饱和羧酸提供了一种原子和能量有效的途径，然而迄今为止，提供高选择性和生产率的合适的多相催化剂仍难以实现。在此，我们演示了在无碱、间歇和连续流动操作下，使用二氧化硅负载的 Pt 纳米颗粒将肉桂醛直接有氧氧化为肉桂酸。通过 XRD、XPS、HRTEM、CO 化学吸附和 N-2 孔隙率测定法对四个系列相关 Pt/二氧化硅催化剂进行表面和本体表征，证明表面 PtO2 是肉桂醛氧化的常见活性位点，其常见周转频率为 49,000 +/- 600 h(-1)；竞争性肉桂醛氢解作用优于金属铂。由于优异的铂分散性，与小面积气相二氧化硅相比，高面积介孔（SBA-15 或 KIT-6）和大孔-介孔 SBA-15 二氧化硅可显着提高产率和肉桂酸产率。高氧分压和连续流动操作可稳定 PtO2 活性位点，防止原位还原和随之而来的失活，进一步提高肉桂酸生产率。
Aerobic selective oxidation of allylic aldehydes offers an atom and energy efficient route to unsaturated carboxylic acids, however suitable heterogeneous catalysts offering high selectivity and productivity have to date proved elusive. Herein, we demonstrate the direct aerobic oxidation of cinnamaldehyde to cinnamic acid employing silica supported Pt nanoparticles under base-free, batch and continuous flow operation. Surface and bulk characterisation of four families of related Pt/silica catalysts by XRD, XPS, HRTEM, CO chemisorption and N-2 porosimetry evidence surface PtO2 as the common active site for cinnamaldehyde oxidation, with a common turnover frequency of 49,000 +/- 600 h(-1); competing cinnamaldehyde hydrogenolysis is favoured over metallic Pt. High area mesoporous (SBA-15 or KIT-6) and macroporous-mesoporous SBA-15 silicas confer significant rate and cinnamic acid yield enhancements versus low area fumed silica, due to superior platinum dispersion. High oxygen partial pressures and continuous flow operation stabilise PtO2 active sites against in-situ reduction and concomitant deactivation, further enhancing cinnamic acid productivity.