Controlling Diphenyl Ether Hydrogenolysis Selectivity by Tuning the Pt Support and H-Donors under Mild Conditions
Controlling Diphenyl Ether Hydrogenolysis Selectivity by Tuning the Pt Support and H-Donors under Mild Conditions
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DOI：
10.1021/acscatal.1c03999
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发表时间：
2021-10
期刊：
影响因子：
12.9
通讯作者：
Chen Zhu;Siyu Ding;H. Hojo;H. Einaga
中科院分区：
文献类型：
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作者：
Chen Zhu;Siyu Ding;H. Hojo;H. Einaga
木质素衍生的芳基醚的C-O键的选择性氢解成芳族化合物是具有挑战性的，因为它总是伴随着氢化（HYD）。迄今为止测试的大多数金属负载催化剂对二苯醚（DPE，木质素中的4-O-5键）的C-O键断裂表现出高效率，但对有价值的芳香族化合物的选择性低。在这里，我们报告了我们的发现，显示了通过调节催化剂载体和反应条件来控制产物选择性的可行性。以异丙醇为氢源，Pt/γ-Al 2 O3催化剂在160 °C下对苯和苯酚的选择性高达95.7%，转化率接近100%。相比之下，在140 °C下，Pt/TiO 2催化剂对饱和芳香族产物（环己烷和环己醇）的选择性高达99%，DPE完全转化。异丙醇脱氢放氢实验表明，Pt/γ-Al 2 O3催化剂上的异丙醇脱氢活性低于Pt/TiO 2催化剂，有效抑制了生成芳烃的深度加氢反应。采用第一性原理计算研究了异丙醇脱氢反应中载体和反应活性中心的作用。基于实验结果和从头算分子动力学模拟，提出了两种Pt/氧化物催化剂上DPE氢解反应的详细机理。
The selective hydrogenolysis of the C–O bonds of lignin-derived aryl ethers into aromatics is challenging because it is always accompanied by hydrogenation (HYD). Most metal-supported catalysts tested so far exhibit high efficiency for the C–O bond cleavage of diphenyl ether (DPE, 4-O-5 linkage in lignin) but low selectivity toward valuable aromatic compounds. Here, we report our discovery showing the feasibility of controlling the selectivity of products by tuning the catalyst support and reaction conditions. Pt/γ-Al2O3exhibited a higher selectivity (95.7%) for aromatic products (benzene and phenol) with a nearly 100% conversion at 160 °C when 2-propanol was used as a hydrogen source. In contrast, up to 99% selectivity for saturated aromatic products (cyclohexane and cyclohexanol) and the full conversion of DPE were yielded over Pt/TiO2at 140 °C. The H2evolution from 2-propanol dehydrogenation confirmed that the dehydrogenation activity of 2-propanol over Pt/γ-Al2O3was lower than that over Pt/TiO2, which effectively suppressed the deep HYD of the formed aromatics. The role of supports and reaction active sites for 2-propanol dehydrogenation was studied by first-principles calculations. Based on the experimental results andab initiomolecular dynamics simulations, the detailed mechanisms of DPE hydrogenolysis over two Pt/oxide catalysts were proposed.