Study On Partial Oxidation Of Methane To Syngas Over Ni-based Monolith Catalyst And Promotion Effects Of CeO₂

In the utilization of natural gas, research on the partial oxidation of natural gas to syngas has attracted increasing attention in the world. Compared with methane reforming with steam, catalytic partial oxidation of methane to syngas is a better approach for methane utilization, for it has many advantages such as less equipment investment, lower power cost, smaller reactor and H₂/CO ratio of syngas close to 2.0, which is favorable to synthesis of methanol or F-T synthesis.In this work, using PEG as dispersant, a series of monolith Ni and Ni-CeO₂ catalysts were prepared by steps of mixing, drying, moulding, calcinations and reduction. The prepared catalysts were characterized by means of particles analyzing, TPR, XRD, SEM and catalytic activity measurements. Additionally, the reaction conditions of n(CH₄)/n(O₂), reaction temperature and gas space velocity for partial oxidation of methane were optimized.Ceria was choosed as a promoter of Ni monolith catalyst in this paper because of its high oxygen-storage capacity and oxygen mobility. The addition methods have considerable effects on the catalyst performance. The results showed that, the addition of cerium nitrate solution made the catalyst has more pores on the surface, better crystal, better distribution ability and higher catalytic activity and stability. The effect of ceria content on activity of Ni-CeO₂ catalyst was also investigated; the results showed that the suitable addition amount of ceria is 10wt%. The proper preparation conditions of monolith Ni-CeO₂ catalyst were as follows:The dosage of PEG 3wt%, the content of ceria 10wt%, calcinations at 500℃for 2h, reduction at 500℃for 1h, sintering at 1000℃for 1h.Monolith Ni-CeO₂ catalyst showed good activity on partial oxidation of methane to syngas. The process conditions were optimized as follows: n (CH₄)/n (O₂)=1.9, reaction temperature 930℃and gas space velocity 1.2×105h-1. Under above conditions, the better results were obtained as follows: CH4 conversion 97%, H₂ selectivity 92% and CO selectivity 98%, and H2/CO in product 1.88.