Effects of Potassium Doping on CO Hydrogenation Over MoS2 Catalysts: A First-Principles Investigation

Journal Article · Tue Jul 01 04:00:00 EDT 2014 · Catalysis Communications, 52:92-97

DOI:https://doi.org/10.1016/j.catcom.2014.02.011· OSTI ID:1136579

Andersen, Amity; Kathmann, Shawn M.; Lilga, Michael A.; Albrecht, Karl O.; Hallen, Richard T.; Mei, Donghai

Periodic density functional theory calculations were performed to explore the effects of doping potassium (K) on the reactivity of CO hydrogenation to mixed higher alcohols over MoS2 catalysts. We found that the doped K species over the model MoS2(100) catalyst surface acts as a unique site for CO adsorption where either the K-C or the K-O bonding is allowed. The charge transfer from the K 4s electron to the conduction band of the MoS2(100) surface slightly enhances CO adsorption at the edge Mo sites. Due to the large electropositive nature, the presence of the surface K species, however, will hinder the dissociative adsorption of hydrogen. As a result, the doping K species drive CO hydrogenation selectivity toward the C2+ alcohols instead of hydrocarbons by increasing CO and decreasing hydrogen coverages on the MoS2 catalysts. To further elucidate the effect of doping K on the shifting of the selectivity toward CO hydrogenation, we calculated several key reaction steps leading to the H2CCO precursor formation, i.e., CO hydrogenation, the C-O bond scission and the C-C coupling (CH2+CO). The C-C coupling step is favorable for both the Mo and S edges. However, the undoped S edge has an overall more thermodynamically favorable reaction profile up to C-O scission compared with the Mo edge. This work was funded by a CRADA project (No. PNNL/297) with Range Fuels. The research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. The work involving the results analysis and mansucript writing was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1136579
• Report Number(s): PNNL-SA-93304; 42295; KC0301020
• Journal Information: Catalysis Communications, 52:92-97, Journal Name: Catalysis Communications, 52:92-97
• Country of Publication: United States
• Language: English

Related Subjects

Environmental Molecular Sciences Laboratory