Oxy-CO_2 Reforming of Methane to Syngas over CoO_x/CeO_2/SA-5205 Catalyst

摘要

The oxy-CO_2 methane reforming (OCRM) process has been investigated over the CoO_x/CeO_2/SA-5205 catalyst at varying reaction temperatures (750-900℃), O_2/CH_4 ratios (0.3-0.45), and space velocities (20 000-100 000 cm~3/g/h). With an increasing OCRM reaction temperature, the contribution from the CO_2 methane reforming reaction increased while that from methane combustion reactions decreased. Correspondingly, there was an increase in the H_2/CO ratio and a sharp decrease in reaction exothermicity. At 900℃ (gas hourly space velocity = 46 000 cm~3/g/h and O_2/CH_4 = 0.4), the OCRM reaction over the CoO_x/CeO_2/SA-5205 catalyst was mildly endothermic with > 90% CH_4 conversion, > 95% H_2 selectivity, and a H_2/CO ratio of 1.63. CH_4 conversion was relatively unaffected by the O_2/CH_4 ratio used in the OCRM reaction; however, CO_2 conversion decreased on increasing the O_2/CH_4 ratio. While H_2 selectivity was not significantly affected by the O_2/CH_4 ratio, the H_2/CO ratio increased linearly with an increasing O_2/CH_4 ratio. The endothermicity of the reaction was found to decrease with an increasing CH_4/O_2 ratio, which can be explained on the basis of increased contribution from the methane partial oxidation reaction with an increasing O_2/CH_4 ratio.