On the enhanced catalytic activity of acid-treated, trimetallic Ni-Mo-W sulfides for quinoline hydrodenitrogenation
On the enhanced catalytic activity of acid-treated, trimetallic Ni-Mo-W sulfides for quinoline hydrodenitrogenation
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DOI：
10.1016/j.jcat.2019.09.034
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发表时间：
2019-12
影响因子：
7.3
通讯作者：
Sylvia Albersberger;Hui Shi;Manuel F. Wagenhofer;Jinyi Han;O. Gutiérrez;J. Lercher
中科院分区：
文献类型：
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作者：
Sylvia Albersberger;Hui Shi;Manuel F. Wagenhofer;Jinyi Han;O. Gutiérrez;J. Lercher
双金属和三金属 Mo(W)S2 硫化物的水酸处理去除了大部分 Ni 硫化物，而不影响 Mo(W)S2 板的完整性。对这些样品的喹啉加氢脱氮 (HDN) 反应路径分析表明，所有催化剂上的活性位点相同，不受 Mo(W)S2 相组成的影响。喹啉的 HDN 主要通过两个环的完全氢化进行，然后脱氮。随着活性位点浓度的增加，沿着这条路线的速率决定步骤转移到稍后的 H 加成，这反映在 H2 中反应级数的增加。虽然氢化速率与喹啉浓度无关，但开环速率（次要路线）取决于喹啉浓度。这种差异归因于介导两种途径的不同吸附物质，即用于开环的N配位中间体到配位不饱和位点（CUS）和用于氢化的质子化中间体。我们推断氢化和开环需要两种类型的表面位点，它们在研究的样品中以几乎相同的比例存在。 HDN 速率与 H2-D2 交换速率的相关性使我们得出结论，Mo(W)S2 相成分控制着 Ni 掺入板坯边缘，从而导致活性位点的浓度不同。通过 H2-D2 交换间接探测到的 SH 基团浓度在富含 W 的三元硫化物相中最高，导致 HDN 比活性比双金属（Ni-Mo 和 Ni-W）样品高 5-10 倍。
Aqueous acid treatment of bi- and trimetallic Mo(W)S2sulfides removed a majority of Ni sulfides without affecting the intactness of the Mo(W)S2slabs. Reaction path analysis of quinoline hydrodenitrogenation (HDN) on these samples suggests identical active sites on all catalysts, unaffected by the composition of the Mo(W)S2phase. HDN of quinoline proceeds primarily via full hydrogenation of both rings followed by the removal of nitrogen. The rate-determining step along this route shifts to a later H-addition as the concentration of active site increases, reflected by the increasing reaction order in H2. While the rate of the hydrogenation was independent of quinoline concentration, the rate of ring opening (the minor route) depended on the quinoline concentration. This difference is attributed to different adsorbed species mediating the two routes, i.e., N-coordinated intermediate to coordinatively unsaturated sites (CUS) for ring opening and protonated intermediate for hydrogenation. We infer that hydrogenation and ring opening require two types of surface sites that are present at nearly identical proportions on the samples studied. The correlation of HDN rates with H2-D2exchange rates led us to conclude that the Mo(W)S2phase composition governs the incorporation of Ni into the slab edge, leading to different concentrations of active sites. The concentration of SH groups, indirectly probed by H2-D2exchange, was highest in a W-rich ternary sulfide phase, leading to 5–10 times higher specific HDN activity than bimetallic (Ni-Mo and Ni-W) samples.