Hydrodesulfurization (HDS) of crude oil plays a vital role in the refining of petroleum products. With ever-increasing regulations restricting the allowable concentrations of sulfur in fuel, further research is required to produce more efficient and effective catalysts. Herein, we have synthesized carbon nanotube (CNT)-supported cobalt-molybdenum (CoMo) catalysts for HDS of dibenzothiophene (DBT) via Co-first and Mo-first sequential impregnation as well as co-impregnation. Spectroscopic analysis shows the formation of a CoMo catalyst with no free sulfided Co phase present. Additionally, CoMo catalysts are found to be predominantly single-layered nanocatalysts layered on the CNT support. Temperature-programmed reduction (TPR) measurements show differences in reducing temperature of the sulfided CoMo catalysts prepared by the different methods, but catalyst activities for HDS of DBT did not fully align with the TPR-predicted order. Thus, provided the reaction temperature is high enough, reducibility may not always be an adequate gauge of catalytic activity. Conversion of DBT was highest in Mo-first sequential impregnation (81.5%), followed by co-impregnation (64%) and Co-first sequential impregnation (60%) on a CNT support. While these results contrast with some others regarding the order of impregnation, we propose that the preferred impregnation order is actually support-dependent, rather than an absolute quality.

中文翻译：

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碳纳米管上修饰的钴钼单层纳米催化剂及其制备条件对其加氢脱硫催化活性的影响

原油的加氢脱硫（HDS）在石油产品的精炼中起着至关重要的作用。随着越来越多的法规限制燃料中硫的允许浓度，需要进一步研究以生产更有效的催化剂。在这里，我们已经合成了碳纳米管（CNT）负载的钴钼（CoMo）催化剂，用于通过Co-first和Mo-first顺序浸渍以及共浸渍来制备二苯并噻吩（DBT）的HDS。光谱分析表明形成了不存在游离硫化的Co相的CoMo催化剂。另外，发现CoMo催化剂主要是在CNT载体上分层的单层纳米催化剂。程序升温还原（TPR）测量表明，采用不同方法制备的硫化CoMo催化剂在还原温度方面存在差异，但是DBT HDS的催化剂活性与TPR预测的顺序不完全一致。因此，如果反应温度足够高，则还原性可能不总是催化活性的适当量度。DBT的转化率最高的是Mo-first顺序浸渍（81.5％），然后是CNT载体上的共浸渍（64％）和Co-first顺序浸渍（60％）。虽然这些结果在浸渍顺序方面与其他一些结果相反，但我们建议首选的浸渍顺序实际上是依赖于支撑的，而不是绝对的质量。DBT的转化率最高的是Mo-first顺序浸渍（81.5％），然后是CNT载体上的共浸渍（64％）和Co-first顺序浸渍（60％）。虽然这些结果在浸渍顺序方面与其他一些结果相反，但我们建议首选的浸渍顺序实际上是依赖于支撑的，而不是绝对的质量。DBT的转化率最高的是Mo-first顺序浸渍（81.5％），然后是CNT载体上的共浸渍（64％）和Co-first顺序浸渍（60％）。虽然这些结果在浸渍顺序方面与其他一些结果相反，但我们建议首选的浸渍顺序实际上是依赖于支撑的，而不是绝对的质量。