Structural changes in PdO/Al2O3 catalysts in liquid phase: from PdO reduction to hydrogenation reaction.

Based on previous knowledge on the effects of pre-reducing agents on the reducibility of PdO/Al2O3 catalysts and on the properties of the supported Pd nanoparticles (NPs), this proposal aims to investigate by High-Q XRD/PDF in situ measurements the isothermal reduction of PdO/Al2O3 catalysts in water in the presence of different reducing agents. The results will contribute to establish the thermodynamics (activation energy) and kinetics (mechanism) of liquid phase PdO reduction as a function of the reducing agents. The same techniques will be applied to investigate the kinetic of consumption of Pd-hydrides and the structural changes in the Pd NPs during the selective hydrogenation of para-chloro-nitrobenzene as probe reaction in the presence of different solvents. This proposal is part of the work of a PhD student sponsored by ESRF and PSI. The measurements performed at ID15A will be complemented by ATR-IR and XAS measurements performed adopting the same experimental set-up.

本提案基于此前关于预还原剂对PdO/Al₂O₃催化剂还原性能以及负载型钯纳米颗粒（Pd nanoparticles, NPs）性质的研究认知，拟通过高Q X射线衍射/对分布函数（High-Q XRD/PDF）原位（in situ）测量技术，探究不同还原剂存在下PdO/Al₂O₃催化剂在水溶液中的等温还原过程。研究结果将助力建立液相PdO还原过程的热力学（活化能）与动力学（反应机理）随还原剂种类变化的关联规律。本研究还将采用相同实验手段，以对氯硝基苯选择性加氢为探针反应，探究不同溶剂条件下钯氢化物的消耗动力学以及Pd纳米颗粒的结构演变。本提案为由欧洲同步辐射光源（ESRF）与保罗·谢尔研究所（PSI）资助的博士生研究工作的一部分。在ID15A光束线开展的同步辐射测量，将辅以采用相同实验配置的衰减全反射红外光谱（ATR-IR）与X射线吸收光谱（XAS）测量。