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首页> 外文期刊>Catalysis science & technology >Formation and stability of an active PdZn nanoparticle catalyst on a hydrotalcite-based support for ethanol dehydrogenation
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Formation and stability of an active PdZn nanoparticle catalyst on a hydrotalcite-based support for ethanol dehydrogenation

机译：一个活跃的PdZn的形成和稳定hydrotalcite-based纳米催化剂支持乙醇脱氢

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摘要

A hydrotalcite-based PdZn nanoparticle catalyst, PdZn/Mg(Al)(Pd)(Zn)O-x has been synthesized via a one-pot procedure. The activation comprising H-2 and air treatment(s) allows tuning the nanoparticle formation and, hence, the catalyst performance. Based on an elaborate set of characterization data from EXAFS, in situ XRD, STEM and CO chemisorption, it is concluded that single reduction leads to the formation of Pd-rich alloy nanoparticles, i.e., a PdZn shell with a Pd core. Cycled reduction, i.e., 3 subsequent hydrogen and air treatments, ensures the formation of more homogeneously mixed PdZn nanoparticles. Compared with a PdZn/ZnO reference catalyst, the nanoparticles obtained after cycled reduction exhibit a higher initial average turnover frequency in ethanol dehydrogenation, i.e., 7.0 molEtOH (mol(Pd) s)(-1) rather than 3.2 molEtOH (mol(Pd) s)(-1). An activity loss is observed during the first hours on stream. It is attributed to coking of the Pd sites which are also deemed responsible for acetaldehyde decomposition. Hence, the acetaldehyde selectivity steadily increases during the first hours on stream. Subsequently, the acetaldehyde space time yield and selectivity stabilize at 0.7 x 10(-4) mol s(-1) kg(Pd)(-1) and 98%, respectively.
机译：一个hydrotalcite-based PdZn纳米颗粒催化剂,PdZn /毫克(Al) (Pd)(锌)O-x被合成通过锅的过程。和空气处理(s)允许调整纳米颗粒的形成,因此,催化剂的性能。表征数据从EXAFS、原位XRD、阀杆和化学吸收作用,得出单级减速导致的形成Pd-rich合金纳米粒子,即PdZn shellPd的核心。随后的氢和空气处理,确保形成更均匀的混合PdZn纳米粒子。催化剂,骑车后获得的纳米颗粒表现出更高的初始平均减少在乙醇脱氢,周转频率例如,7.0 molEtOH(摩尔(Pd) s)(1),而不是3.2molEtOH(摩尔(Pd) s)(1)。观察到在第一小时流。归因于炼焦的Pd网站也被视为负责乙醛分解。在第一个选择性稳步增加小时流。时空收率和选择性稳定在0.7x 10(4)摩尔s(1)千克(Pd)(1)和98%,分别。

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