Propyne Hydrogenation over a Pd/Cu(111) Single-Atom Alloy Studied using Ambient Pressure Infrared Spectroscopy
Propyne Hydrogenation over a Pd/Cu(111) Single-Atom Alloy Studied using Ambient Pressure Infrared Spectroscopy
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DOI：
10.1021/acscatal.0c02475
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发表时间：
2020-09-04
期刊：
影响因子：
12.9
通讯作者：
Trenary, Michael
中科院分区：
文献类型：
--
作者：
Abdel-Rahman, Mohammed K.;Trenary, Michael
用偏振依赖反射吸收红外光谱法研究了Pd/Cu（111）单原子合金催化丙炔加氢制丙烯的反应。该方法允许同时监测气相中的反应物和产物以及反应期间吸附在表面上的物质。并与无Pd Cu（111）催化剂的丙炔加氢反应以及以前的Pd/Cu SAA/Al 2 O3催化剂的研究结果进行了比较。丙烯的产生发生在383 K及以上的温度，如在912 cm（-1）处出现红外峰所示，这是气相丙烯的独特特征。在300 K时，丙炔在Cu（111）表面上形成双-s/双-p结构，其光谱与文献报道的150 K时丙炔在Cu（111）表面上的吸附光谱一致.当温度高于400 K时，2968 cm（-1）处的峰强度急剧增加，表明表面上存在碳质层。在912和3322 cm-1处的气相峰的级数分别用于计算丙烯的生产速率和丙炔的消耗速率。该反应速率用于确定Pd/Cu（111）SAA表面上的反应在383 K下的转换频率为25.4 s（-1）。该反应不受碳质层的存在的阻碍，即使对于如此厚的层，只有碳是可检测的表面上的俄歇电子能谱。
The hydrogenation of propyne (C3H4) to propene (C3H6) using a Pd/Cu(111) single-atom alloy (SAA) has been studied using polarization-dependent reflection absorption infrared spectroscopy. This method allows for simultaneous monitoring of reactants and products in the gas phase and species adsorbed on the surface during the reaction. The results were compared with the hydrogenation of propyne using Pd-free Cu(111) as well as with previous studies on Pd/Cu SAA catalysts supported on alumina. Propene production occurs at temperatures of 383 K and above as indicated by the appearance of an infrared peak at 912 cm(-1), which is a unique characteristic feature of gas phase propene. Propyne was found to adsorb on the surface at 300 K in the presence of gas phase propyne to form a di-s/di-p structure, as the spectrum was identical to that reported in the literature for propyne adsorbed on Cu(111) at 150 K in ultrahigh vacuum. The presence of a carbonaceous layer on the surface is indicated by a dramatic increase in the intensity of a peak at 2968 cm(-1) at temperatures above 400 K. The progression of gas phase peaks at 912 and 3322 cm-1 was used to calculate the rate of production of propene and the rate of consumption of propyne, respectively. This reaction rate was used to determine a turnover frequency of 25.4 s(-1) at 383 K for the reaction on the Pd/Cu(111) SAA surface. The reaction was not impeded by the presence of the carbonaceous layer, even for a layer so thick that only carbon was detectable on the surface with Auger electron spectroscopy.