Acrolein Hydrogenation Catalyzed by Pt(111): Effect of Carbonaceous Deposits on Kinetics
Acrolein Hydrogenation Catalyzed by Pt(111): Effect of Carbonaceous Deposits on Kinetics
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DOI：
10.1021/acscatal.3c03870
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发表时间：
2023-10
期刊：
影响因子：
12.9
通讯作者：
Mindika Tilan Nayakasinghe;Yang Xu;F. Zaera
中科院分区：
文献类型：
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作者：
Mindika Tilan Nayakasinghe;Yang Xu;F. Zaera
以Pt（111）单晶为催化剂，测定了丙烯醛加氢反应的绝对翻转频率。该反应的动力学发现有些复杂，因为表面同时沉积了强吸附的碳质沉积物，通过原位反射-吸收红外吸收光谱（RAIRS）确定为乙炔，烯酮和一氧化碳的混合物。使用CO程序升温解吸法（TPD）滴定了仍具有催化活性的表面部分作为反应温度的函数，所得值用于估计真实的周转率，由此得出活化能为~ 15 kJ/mol。研究发现，与其它烯烃加氢过程一样，不可逆吸附碳质沉积物的积累显著影响丙烯醛加氢催化的活性和选择性；丙醛是这里的主要产物（约90%），这需要C = C双键优先加氢。在此基础上，建议通过对表面进行改性，减少或改变这些表面烃碎片的特征，可以提高Pt的催化性能。
Absolute turnover frequencies for the hydrogenation of acrolein were measured by using a Pt(111) single crystal as the catalyst. The kinetics of the reaction were found to be somewhat complex because of interference from the simultaneous deposition of strongly adsorbed carbonaceous deposits on the surface, identified here as a mix of ethylidyne, ketene, and carbon monoxide by using in situ reflection–absorption infrared absorption spectroscopy (RAIRS). The fraction of the surface still active for catalysis was titrated as a function of reaction temperature using CO temperature-programmed desorption (TPD), and the resulting values used to estimate true turnover frequencies, from which an activation energy of ∼15 kJ/mol was derived. It was found that the buildup of irreversibly adsorbed carbonaceous deposits significantly affects both the activity and the selectivity of the acrolein hydrogenation catalysis, as it does in other olefin hydrogenation processes; propanal is the main product here (∼90%), and that requires the preferential hydrogenation of the C═C double bond. On the basis of these results, it is suggested that the catalytic performance of Pt may be improved by modifying the surface to either minimize or change the character of these surface hydrocarbon fragments.