The effect of H2S on the CO2 + CH4 reaction in the presence of different titania supported noble metal catalysts was studied. The reaction between CO2 and CH4 proceeded rapidly above 673 K on TiO2 supported noble metals to give CO and H2 with different ratios. In the presence of H2S, the initial rate of H2 or CO formation and the conversion of the reactants decreased in time in all cases. When the H2S concentration was increased in the reacting gas mixture (116 ppm) the conversion of CH4 or CO2 decreased more rapidly. In the absence of H2S on TiO2 supported samples, the CH4, CO2 conversion, and the CO/H2 ratio did not change significantly during the reaction. H2S poisoned the CO2 + CH4 reaction, while the CO2 + H2 reaction was only effected slightly by the same amount of H2S. The rate of hydrogen formation in the CO2 + CH4 reaction decreased while the consumption rate of it in a secondary reaction remained the same. The most part of the adsorbed H2 desorbed from the TiO2 and from TiO2 supported noble metals as SO2.
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