Producing Of Syngas By Catalytic Reforming Of Methane In Short Contact Time Reactor

Reforming of natural gas has become the dominant route of natural gas utilization in chemical industry. On the other hand, reforming of natural gas by short contact time reactor (SCTR) can be used as the source of H₂ for natural gas engine. In this study, a test bench was designed and built to study the laws of natural gas reforming in SCTR. Both partial oxidation of methane and autothermal reforming of methane with CO₂ were carried out over two noble metal catalysts, Pt/α-Al₂O₃ and Rh/α-Al₂O₃, which were prepared by conventional impregnation method.In the experiments of partial oxidation of methane, the conversion rate of CH₄, selectivity of H₂ and CO, the ratio of H₂/CO in the exhaust, temperature in the catalyst bed was recorded when the ratio of CH₄/O₂, N₂ consentration, feed gas temperature and the total flow rate of the feed gas were changed.It was found that the majority of syngas was produced by direct oxidation of methane when CH₄/O₂/N₂ gas-mixture went through the reactor packed with Pt catalyst. On the Rh catalyst, however, most of methane was firstly oxidized into H₂O and CO₂, and then the residual methane was reformed by the products of H₂O and CO₂. Partial oxidation of methane on Rh shows higher conversion of CH₄, higher selectivity of H₂ and CO, higher ratio of H₂/CO in the exhaust, but lower temperature than that on Pt. To increase the reaction temperature will help to increase the selectivity of CO and H₂. And lower partial pressure of O₂ also benefits the selectivity of CO and H₂. The concentration of the catalyst surface O* has greater effect on reforming reaction than temperature; the concentration of the catalyst surface O* has greater effect on steam reforming than on CO₂ reforming. The effect of temperature on H₂ desorption is greater than that on CO desorption; the effect of temperature on steam reforming reaction is greater than that on CO₂ reforming reaction.In autothermal reforming of methane with CO₂, the conversion rate of CH₄ and CO₂, selectivity of H₂, yields of H₂ and CO, the ratio of H₂/CO in the exhaust, temperature in the catalyst bed was recorded when the ratio of CH₄/CO₂/O₂, feed gas temperature and the total flow rate of the feed gas were changed.It was found that the reaction on Rh shows higher conversion of CH₄ and CO₂, higher selectivity of H₂, higher ratio H₂/CO in the exhaust, larger H₂ and CO yields, but lower temperature than that on Pt. Both conversion rates of CH₄ and CO₂ rises, when the concentration of O₂ in the feed gas increases, this suggests that temperature has greater effect on the conversion rate of CO₂ than the concentration of O₂ in the feed gas. During the reforming process over Rh and Pt catalysts, the coversion rates of CH₄ and CO₂ increases more and more slower when the total flow rate of the feed gas increases.