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Unravelling the Role of Oxygen Vacancies in the Mechanism of the Reverse Water–Gas Shift Reaction by Operando DRIFTS and Ultraviolet–Visible Spectroscopy
ACS Catalysis ( IF 11.3 ) Pub Date : 2018-07-03 00:00:00 , DOI: 10.1021/acscatal.8b02121
Luis F. Bobadilla 1 , José L. Santos 1 , Svetlana Ivanova 1 , José A. Odriozola 1 , Atsushi Urakawa 2
Affiliation  

The reaction mechanism of the reverse water–gas shift (RWGS) reaction was investigated using two commercial gold-based catalysts supported on Al2O3 and TiO2. The surface species formed during the reaction and reaction mechanisms were elucidated by transient and steady-state operando DRIFTS studies. It was revealed that RWGS reaction over Au/Al2O3 proceeds through the formation of formate intermediates that are reduced to CO. In the case of the Au/TiO2 catalyst, the reaction goes through a redox mechanism with the suggested formation of hydroxycarbonyl intermediates, which further decompose to CO and water. The Ti3+ species, the surface hydroxyls, and oxygen vacancies jointly participate. The absence of carbonyl species adsorbed on gold particles during the reaction for both catalysts indicates that the reaction pathway involving dissociative adsorption of CO2 on Au particles can be discarded. To complete the study, operando ultraviolet–visible spectroscopy was successfully applied to confirm the presence of Ti3+ and to understand the role of the oxygen vacancies of TiO2 support in activating CO2 and thus the subsequent RWGS reaction.

中文翻译:

通过操作DRIFTS和紫外-可见光谱揭示氧空位在逆向水煤气变换反应机理中的作用

利用两种负载在Al 2 O 3和TiO 2上的商品化金基催化剂,研究了逆水煤气变换(RWGS)反应的反应机理。通过瞬时和稳态操作DRIFTS研究阐明了在反应和反应机理过程中形成的表面物质。结果表明,在Au / Al 2 O 3上进行RWGS反应是通过形成还原为CO的甲酸酯中间体而进行的。在Au / TiO 2催化剂的情况下,该反应通过氧化还原机理进行,并建议形成羟基羰基。中间体,进一步分解为一氧化碳和水。钛3+物种,表面羟基和氧空位共同参与。对于两种催化剂,在反应期间在金颗粒上没有吸附的羰基物质表明,可以放弃涉及CO 2在金颗粒上的解离吸附的反应途径。完成研究,operando紫外可见分光法成功地应用于确认的Ti的存在3+和理解的TiO氧空位的作用2支持在激活CO 2,因此随后的反应RWGS。
更新日期:2018-07-03
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