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Controlling Diphenyl Ether Hydrogenolysis Selectivity by Tuning the Pt Support and H-Donors under Mild Conditions
ACS Catalysis ( IF 11.3 ) Pub Date : 2021-10-01 , DOI: 10.1021/acscatal.1c03999
Chen Zhu 1 , Siyu Ding 1 , Hajime Hojo 1 , Hisahiro Einaga 1
Affiliation  

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-Al2O3 exhibited 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/TiO2 at 140 °C. The H2 evolution from 2-propanol dehydrogenation confirmed that the dehydrogenation activity of 2-propanol over Pt/γ-Al2O3 was 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 and ab initio molecular dynamics simulations, the detailed mechanisms of DPE hydrogenolysis over two Pt/oxide catalysts were proposed.

中文翻译:

通过在温和条件下调节 Pt 载体和 H 供体来控制二苯醚氢解选择性

将木质素衍生的芳基醚的 C-O 键选择性氢解为芳烃具有挑战性,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,显示了通过调整催化剂载体和反应条件来控制产品选择性的可行性。Pt/γ-Al 2 O 3当使用 2-丙醇作为氢源时,在 160 °C 下,芳烃产物(苯和苯酚)的转化率接近 100%,显示出更高的选择性(95.7%)。相比之下,在 140 °C 下,在 Pt/TiO 2上产生了高达 99% 的饱和芳烃产物(环己烷和环己醇)选择性和 DPE 的完全转化率。2-丙醇脱氢析出H 2证实2-丙醇在Pt/γ-Al 2 O 3上的脱氢活性低于在Pt/TiO 2 上的脱氢活性,这有效地抑制了形成的芳烃的深度 HYD。通过第一性原理计算研究了载体和反应活性位点在 2-丙醇脱氢中的作用。基于实验结果和从头分子动力学模拟,提出了两种 Pt/氧化物催化剂上 DPE 氢解的详细机制。
更新日期:2021-10-15
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