Dry Reforming of Methane Over Novel Composite Catalysts for High Yield Synthesis Gas(PPT)

摘要

Dry reforming of methane using carbon dioxide is an environmentally friendly process for the conversion of two greenhouse gasses into synthesis gas. The conversion of methane and carbon dioxide, the yield of hydrogen and carbon monoxide, and the mole ratio of hydrogen to carbon monoxide are function of temperature and catalyst identity. Thus, we focused in the present work in preparing novel composite catalysts, made of y-alumina doped with 1 wt% lanthanide (Y, La, Ce, Pr, or Er) and bimetallic cobalt molybdenum carbide. The prepared catalysts were examined in a tubular, stainless steel, continuous flow, fixed bed reactor under atmospheric pressure with 1:1:1 mole ratio of methane to carbon dioxide to nitrogen. We found that the identity of lanthanide dopant was imperative for the performance of these catalysts. The conversion of reactants and hydrogen/carbon monoxide mole ratio increased with increasing temperature from 700°C to 850°C for all catalysts except for the one doped with lanthanum, which showed very high, stable conversion (>96%) and stable hydrogen/carbon monoxide mole ratio of ～1.0 over this temperature range. However, all catalysts exhibited stability for reactant conversion and product yield at the optimum temperature of 850°C upon testing for five hours. Catalysts doped with yttrium, praseodymium, or erbium resulted at 850°C in higher yield of hydrogen and carbon monoxide than those doped with lanthanum and cerium. However, all catalysts resulted in ～1.1 hydrogen/carbon monoxide mole ratio, which is higher than the ideal value of one. The findings might indicate that the ionic radius and electronegativity of the lanthanide dopant are key parameters. In addition, the findings explicitly showed that reverse water gas shift, methane cracking and reverse Boudouard are the main side reactions.