Controlled atmosphere 13C and 1H MAS NMR study of reforming route of methane with carbon dioxide over Rh/SBA-15

The mechanism of methane reforming with carbon dioxide over 1.0 wt.% Rh/SBA-15 catalyst has been studied by the C-13 and H-1 magic-angle spinning (MAS) NMR spectroscopies under controlled atmosphere condition using (CH4)-C-13 + (CO2)-C-12 and (CH4)-C-12 + (CO2)-C-13 as reactants. The effect of temperature in the region of 298-1023 K on the reaction was investigated and the contents of various C-13 and H-1 species were obtained quantitatively by the NMR technique. When treated at 573 K, the carbon exchange between methane and carbon dioxide can be observed. With the temperature rising to 773 K, the adsorbed CH3O* species is formed but no reforming reaction occurs. In the high temperature range of 873-1023K, the reforming reaction was observed with concomitant appearance of the adsorbed CH2O* species and the intensity of both CH3O* and CH2O* increases with increasing temperature, indicating that the decomposition of CH3O* to CH2O* occurs and the products of dry reforming are formed from decomposition of the adsorbed CH2O* species. 2011 Elsevier B.V. All rights reserved.