Hydrogen production in ultra-rich filtration combustion of methane and hydrogen sulfide

Filtration combustion waves formed in an inert porous media were analyzed comparatively for methane (CH4)/air and diluted hydrogen sulfide (20% H2S+80% N2)/air mixtures. Temperature, velocity, and chemical products of the combustion waves were studied experimentally in the range of equivalence ratios (ϕ) from 1 to 2.5 for methane and from 1 to 5.5 for hydrogen sulfide, at a filtration velocity of 12 cm/s. The practical goal of the study in the rich and ultra-rich region was to explore the extent of conversion of these reactants into commercially viable products such as hydrogen (H2), syngas (H2+CO), and sulfur (S2). For both methane and hydrogen sulfide combustion, upstream (underadiabatic) propagation corresponds to the range of equivalence ratios from stoichiometry to 1.7, and downstream (superadiabatic) wave propagation was observed for ultrarich (ϕ⩾1.7) mixtures. The products of methane partial oxidation, dominant for ultra-rich waves, were: H2, CO, and C2 hydrocarbons where up to 60% of the methane was converted to CO and H2. Similar observation for H2S partial oxidation products reveals a maximum conversion rate of 20% to H2 and 50% for S2.