Liquid hydrogen production via hydrogen sulfide methane reformation

Hydrogen sulfide (H2S) methane (CH4) reformation (H2SMR) (2H2S + CH4 = CS2 + 4H2) is a potentially viable process for the removal of H2S from sour natural gas resources or other methane containing gases. Unlike steam methane reformation that generates carbon dioxide as a by-product, H2SMR produces carbon disulfide (CS2), a liquid under ambient temperature and pressure—a commodity chemical that is also a feedstock for the synthesis of sulfuric acid. Pinch point analyses for H2SMR were conducted to determine the reaction conditions necessary for no carbon lay down to occur. Calculations showed that to prevent solid carbon formation, low inlet CH4 to H2S ratios are needed. In this paper, we analyze H2SMR with either a cryogenic process or a membrane separation operation for production of either liquid or gaseous hydrogen. Of the three H2SMR hydrogen production flowsheets analyzed, direct liquid hydrogen generation has higher first and second law efficiencies of exceeding 80% and 50%, respectively.