Catalytic combustion of natural gas as the role of on-site heat supply in rapid catalytic CO2-H2O reforming of methane

Development in highly active catalysts for the reforming of methane with H2O, CO2, and H2O + CO2, and partial oxidation of methane was conducted to produce hydrogen with high reaction rates. A Ni-based three-component catalyst such as Ni-La2O3-Ru or Ni-Ce2O3-Pt supported on alumina wash-coated ceramic fiber in a plate shape was very suitable for both reactions. The catalyst composition was set at 10 wt.-% Ni, 5.6 wt.-% La2O3, and 0.57 wt.-% Ru for example, or molar ratios of these components were 1:0.2:0.03. Even with such a low concentration, the precious metal enhanced the reaction rate markedly, and this synergistic effect was ascribed to the hydrogen spillover effect through the part of precious metal and it resulted in a more reduced surface of the main catalyst component. In particular, a marked enhancement in the reaction rate of CO2-reforming of methane was observed by the modification of a low concentration Rh to the Ni-Ce2O3-Pt catalyst. Very high space-time yields of H-2 (i.e., 8300 mol/l h in partial oxidation of methane at 600 degrees C with a methane conversion of 37.5%, and 3585 mol/l h in CO, reforming of methane at 600 degrees C with a methane conversion of 58%) were realized in those reactions. By combining the catalytic combustion reaction, methane conversion to syngas was markedly enhanced, and even with a very short contact time (10 ms) the conversion of methane increased more than that at 50 ms. The space-time yield of hydrogen amounted to 2,780 mol/l h with a methane conversion of 90% at 700 degrees C. Furthermore, in a reaction of CH4-CO2-H2O-O-2 on the four components catalyst, an extraordinarily high space-time yield of hydrogen, 12 190 mol/l h, could be realized under the conditions of very high space velocity (5 ms).