화학공학소재연구정보센터
Materials Chemistry and Physics, Vol.200, 223-232, 2017
Sulfated CexZr1-xO2 oxides. Surface properties and performance for methane oxidation under fuel-rich conditions
Two series of sulfated zirconia-ceria based catalysts have been prepared by coprecipitation of the Zr4+ and Ce3+ salts, which were then sulfated by impregnation using H2SO4 and [(NH4)(2)S2O8] and calcined at 650 degrees C for 4 h. The sulfated and persulfated Zr-Ce-O samples were synthesized with Zr/Ce ratios ranging from 1 to 15. The textural, structural and surface characteristics of the resulting modified catalysts were determined by N-2 adsorption-desorption, XRD, XPS spectroscopy and TPD of NH3, and results were related to their catalytic behaviour. The catalysts were tested in the direct conversion of methane at high temperature (650 degrees C) under fuel-rich conditions to obtain C-1 oxygenates (CH3OH and HCHO). Experiments were conducted using low O-2/CH4 ratio mixtures and high space velocity. It was shown that O-2/CH4 feeds resulted in practically total combustion of CH4 when sulfated/persulfated ceria-zirconia catalysts are used, while the nature of the different phases modifies the surface acidity, which plays a crucial role on the extent of deep oxidation reactions. (C) 2017 Elsevier B.V. All rights reserved.