Methanation and Fischer-Tropsch studies on potassium-promoted silica-supported Ru catalysts

• Published in: Journal of catalysis Vol. 77; no. 2; pp. 338 - 347
• Main Authors: Gonzalez, Richard D., Miura, Hiroshi
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.01.1982
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/0021-9517(82)90177-4

The role of potassium as a promoter in the methanation and Fischer-Tropsch reaction has been studied. When the potassium content of a series of silica-supported Ru catalysts was increased, turnover numbers for both methane and hydrocarbon formation decreased. Significant increases in the selectivity for higher hydrocarbon and olefin formation occurred as the potassium concentration was increased. The results of a temperature-programmed desorption study showed that the binding sites of CO on Ru were significantly changed due to the presence of the potassium. When the potassium concentration was increased, the high-temperature desorption maxima centered at 370 °C increased relative to the low-temperature desorption maxima at 200 °C. This result is interpreted in terms of the stronger CRu bond resulting from the presence of the potassium. The results of the temperature-programmed desorption study were verified using in situ infrared spectroscopy. As the potassium content of the RuSiO 2 catalysts was increased, additional CO infrared bands assigned to more strongly bound CO were observed. An in situ infrared temperature-programmed reaction study for the potassium-promoted catalyst showed that the more weakly bound CO desorbed without undergoing reaction to form methane.