A novel catalytic process for SNG synthesis

Methane rich city gas has been synthesized by means of steam retorming of naphtha; however, the produced gas always contains significant concentration of CO and CO₂. Therefore, development of a methane production process containing no CO and CO₂ removal processes is strongly requested. Authors reported in the previous paper that C₃H₈→2CH₄+C(1) took place over Ni/SiO₂ with 90% selectivity. In this paper, the catalyst supports were studied and found that neutral SiO₂ and α-Al₂O₃ are suitable but the activity was much reduced over Ni supported on acidic SiO₂-Al₂O₃. Catalyst was diluted by various materials to avoid blocking-up by the deposited carbon. Several diluted materials affected the conversion, α-Al₂O₃ and basic MgO accelerated the reaction which may be due to interaction between Ni and dilution materials with direct contact. Over Ni/SiO₂, reaction (1) took place with 90% selectivity, so that the produced gas always contained H₂ formed by the C₃H₈→3C+4H₂(2). It has confirmed that H₂ in a high concentration of CH₄ can be reacted with C₃H₈ to produce CH₄. From these results, a following simple synthesis process can be constituted; the first step is CH₄, H₂, and solid C formation from C₃H₈, and the second step is succeeding H₂ consumption process of the produced gas in the first step.