Vacuum promoted methane decomposition for hydrogen production with carbon separation: parameter optimization and economic assessment

Abstract Catalytic methane decomposition (CMD) is a promising method for directly extracting hydrogen from methane. Nevertheless, relatively low methane conversion and carbon deposition on the catalyst are two main shortcomings to be resolved. A new process, vacuum promoted methane decomposition with carbon separation (VPMDCS), is proposed and simulated by Aspen Plus. The VPMDCS system is comprised of two reactors, a methane decomposition reactor (MDR) and a carbon separation reactor (CSR), which continuously generates hydrogen in the MDR and converts carbon into CO basically in the CSR based on Le Chatelier’s principle. The effects of methane decomposition temperature and pressure, gasifying agent concentration, CO2/C molar ratio, carbon separation temperature and pressure were comprehensively investigated and optimized. Besides, an economic analysis was conducted compared with that of steam methane reforming, evaluating the competitiveness of VPMDCS. Results reveal that VPMDCS can produce high-purity H2 and CO in the MDR and CSR, respectively, obtaining CH4 conversion of 99.18%, and H2 and CO concentrations of both 99.59 vol%. Economic analysis indicates that the cost to produce hydrogen in the VPMDCS process is 5.40 €/kg, which is somewhat competitive compared to hydrogen produced by small-scale SRM (4.55 €/kg).