Investigation of decomposition and partial oxidation of mixed acid gas and methane for syngas production

Abstract

Reaction processes of decomposition and partial oxidation of a mixture of acid gas (H2S and CO2) and methane (CH4) could enable the efficient production of valuable syngas resource (H2 and CO). In this work, the decomposition and partial oxidation of H2S–CH4–CO2 system was experimentally studied in a tube furnace. Effects of temperature, CH4 and CO2 addition, equivalence ratio and residence time were studied for syngas production and H2/CO variation. Extended temperature and pressure were then studied by equilibrium calculation for thermodynamic analysis in Aspen Plus software. The results showed the increasing temperature favored reactant conversion and syngas production. H2S decomposition was the dominant reaction at temperature below 1050 °C while threshold temperature for CH4 conversion over H2S was about 1100 °C. H2 was formed mainly via H2S decomposition at low temperatures. CH4 addition promoted H2 formation and conversely restrained H2S conversion. The introduction of O2 brought partial oxidation, favored the reaction rate, balanced H2/CO but reduced syngas production. H2/CO ratio also remained at an appropriate level at high CO2 addition since CO2 evidently adjusted the ratio via CO2+H2↔CO + H2O. However, this CO2 reactivity was only adequately expressed under high temperature and extended residence time. Equilibrium calculation confirmed experimental variation trends and revealed reducing pressure favored the syngas production. It could be inferred that extended residence time, higher temperature, suitable equivalence ratio, CH4 and CO2 addition and low pressure could enable improvement in both syngas production and H2/CO. This study revealed high syngas production and adjustment of H2/CO could be realized in H2S–CH4–CO2 system and this might be of great practical in industry.