Density Functional Theory Investigation on Thiophene Hydrodesulfurization Mechanism Catalyzed by ReS2 (001) Surface

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• 作者：Yucheng Huang ; Hai Liu ; Xi Chen ; Danmei Zhou ; Chan Wang ; Jinyan Du ; Tao Zhou ; Sufan Wang
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：June 9, 2016
• 年：2016
• 卷：120
• 期：22
• 页码：12012-12021
• 全文大小：612K
• 年卷期：0
• ISSN：1932-7455

文摘

We present density functional theory calculations on the reaction mechanism of thiophene hydrodesulfurization (HDS) over ReS₂ (001) surface under typical HDS reaction conditions. It is found that thiophene adopts an “upright” adsorption configuration with the binding energy of 1.26 eV. Considering the factors such as Bader charge, two reaction mechanisms, named direct desulfurization (DDS) to the product of butadiene and hydrogenation (HYD) to 2-butene, 1-butene, and butane, are systematically investigated. Results show that H prefers to attack thiophenic C before the first C–S bond rupture but begins to hydrogenate S_T (S atom of thiophene) after ring-opening. Prehydrogenation has different effect on the activity of C–S bond breaking. When the ring is intact, it has nominal effect; but when the ring is open, appropriate prehydrogenation can dramatically decrease the energy barrier while complete hydrogenation makes the barrier rise again due to stereohindrance effect. The DDS mechanism is proved to be kinetically unfavorable while 2-butene is suggested to be a predominated product for HYD mechanism. The role of S_a (preadsorbed S) is a “ladder” which helps H approach the thiophenic molecule while S_T acts as an “intermediary” for H exchange. Changing reaction conditions through partial pressure of H₂ can only alter the rate-determining step but has nothing to do with the catalytic selectivity.