Effects of Potassium and Manganese Promoters on Nitrogen-Doped Carbon Nanotube-Supported Iron Catalysts for CO2 Hydrogenation

• Published in: Engineering (Beijing, China) Vol. 3; no. 3; pp. 385 - 392
• Main Authors: Kangvansura, Praewpilin, Chew, Ly May, Kongmark, Chanapa, Santawaja, Phatchada, Ruland, Holger, Xia, Wei, Schulz, Hans, Worayingyong, Attera, Muhler, Martin
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-06-2017; Scientific Equipment Center, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand%Laboratory of Industrial Chemistry, Ruhr-University Bochum, Bochum 44780, Germany%Department of Materials Science, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand%Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand%Engler-Bunte-Institute, Karlsruhe Institute of Technology, Karlsruhe 76131, Germany; Elsevier
• Subjects: CO2 hydrogenation; Iron catalyst; Manganese promoter; Nitrogen-doped carbon nanotubes; Potassium promoter; Potassium promoter; Iron catalyst; Nitrogen-doped carbon nanotubes; CO2 hydrogenation; Manganese promoter
• ISSN: 2095-8099
• DOI: 10.1016/J.ENG.2017.03.013

Nitrogen-doped carbon nanotubes (NCNTs) were used as a support for iron (Fe) nanoparticles applied in carbon dioxide (CO2) hydrogenation at 633K and 25 bar (1 bar = 105 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 3.1L·(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 60h of reaction time. The structural effect of the Mn promoter was demonstrated by X-ray diffraction (XRD), temperature-programmed reduction (TPR) with molecular hydrogen (H2), and in situ X-ray absorption near-edge structure (XANES) analysis. The Mn promoter stabilized wüstite (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.