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4261825 
Journal Article 
Effects of Potassium and Manganese Promoters on Nitrogen-Doped Carbon Nanotube-Supported Iron Catalysts for CO2 Hydrogenation 
Kangvansura, P; Chew, LyMay; Kongmark, C; Santawaja, P; Ruland, H; Xia, Wei; Schulz, H; Worayingyong, A; Muhler, M 
2017 
0 
Engineering
ISSN: 1947-3931 
3 
3 
385-392 
WOS:000412748100015 
Nitrogen-doped carbon nanotubes (NCNTs) were used as a support for iron (Fe) nanoparticles applied in carbon dioxide (CO2) hydrogenation at 633 K and 25 bar (1 bar = 10(5) Pa). The Fe/NCNT catalyst promoted with both potassium (K) and manganese (Mn) showed high performance in CO2 hydrogenation, reaching 34.9% conversion with a gas hourly space velocity (GHSV) of 3.1 L.(g.h)(-1). Product selectivities were high for olefin products and low for short-chain alkanes for the K-promoted catalysts. When Fe/NCNT catalyst was promoted with both K and Mn, the catalytic activity was stable for 60 h of reaction time. The structural effect of the Mn promoter was demonstrated by X-ray diffraction (XRD), temperature-programmed reduction (TPR) with molecular hydrogen (H-2), and in situ X-ray absorption near-edge structure (XANES) analysis. The Mn promoter stabilized wustite (FeO) as an intermediate and lowered the TPR onset temperature. Catalytic ammonia (NH3) decomposition was used as an additional probe reaction for characterizing the promoter effects. The Fe/NCNT catalyst promoted with both K and Mn had the highest catalytic activity, and the Mn-promoted Fe/NCNT catalysts had the highest thermal stability under reducing conditions. (C) 2017 THE AUTHORS. Published by Elsevier LTD on behalf of the Chinese Academy of Engineering and Higher Education Press Limited Company. 
CO2 hydrogenation; Iron catalyst; Nitrogen-doped carbon nanotubes; Manganese promoter; Potassium promoter