Abstract

Key properties of silicate glasses are determined. These include the ability to stabilize the highly dispersed Pd nanoparticles in a bulk of fiberglass (FG), the high solubility of acetylene and hydrogen, and their increased mobility. Together, these ensure the high activity and selectivity of Pd/FG catalysts during the hydrogenation of acetylene in an excess of ethylene in a wide range of acetylene conversion up to its complete conversion. It is found that for a wide range of mono- and bimetallic systems, including catalysts with single palladium atoms, the TOF value depends weakly on the dispersion of the palladium and nature of the support, i.e., the reaction can be considered structure-insensitive. A tendency toward a lower frequency of turnover is nevertheless observed upon moving to single palladium atoms, due likely to the rate of hydrogen dissociation or its spillover slowing down. Based on kinetic isotope data, undesirable contributions to the selectivity of process resulting from the hydrogenation of acetylene and ethylene from the gas phase to ethane are determined quantitatively. The high selectivity of bimetallic alloyed systems with single palladium atoms is due to the low rate of hydrogenation of weakly absorbed ethylene to ethane, while that of Pd/FG catalysts results from the complete elimination of the hydrogenation of ethylene from the gas phase.

中文翻译：

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Pd玻璃纤维催化剂上乙炔的选择性加氢

摘要

确定了硅酸盐玻璃的关键性能。这些包括稳定大量玻璃纤维（FG）中高度分散的Pd纳米颗粒的能力，乙炔和氢的高溶解度以及增加的迁移率。在一起，它们确保了乙炔在过量乙炔中的乙炔加氢过程中的高活性和选择性，且乙炔的转化范围很广，直至完全转化为止。发现对于包括单钯原子的催化剂在内的广泛的单金属和双金属体系，TOF值在很小程度上取决于钯的分散性和载体的性质，即，该反应可被认为对结构不敏感。不过，在转移到单个钯原子时，观察到了较低的周转率趋势，可能是由于氢的解离速率或其溢出速度变慢。基于动力学同位素数据，定量确定了乙炔和乙烯从气相加氢成乙烷对过程选择性的不良影响。具有单个钯原子的双金属合金体系的高选择性是由于弱吸收的乙烯向乙烷的氢化率低，而Pd / FG催化剂的选择性则是由于从气相中完全消除了乙烯的氢化作用所致。