International Journal of Energy Research, Vol.43, No.8, 3330-3345, 2019
H2S effect on dry reforming of biogas for syngas production
The effect of hydrogen sulfide (H2S) on dry reforming of biogas for syngas production was studied both experimentally and theoretically. In the experimental work, the H2S effect on Ni-based catalyst activity was examined for reaction temperatures ranging from 600 degrees C to 800 degrees C. It was found that the presence of H2S deactivated the Ni-based catalysts significantly because of sulfur poisoning. Although bimetallic Pt-Ni catalyst has better performance compared with monometallic Ni catalyst, deactivation was still found. The time-on-stream measured data also indicated that sulfur-poisoned catalyst can be regenerated at high reaction temperatures. In the theoretical work, a thermodynamic equilibrium model was used to analyze the H2S removal effect in dry reforming of H2S-contained biogas. Calcium oxide (CaO) and calcium carbonate (CaCO3) were used as the H2S sorbent. The results indicated that H2S removal depends on the initial H2S concentration and reaction temperature for both sorbents. Although CO2 was also removed by CaO, the results from equilibrium analysis indicated that the dry reforming reaction in the presence of CaO was feasible similar to the sorption enhanced water-gas shift and steam-methane reforming reactions. The simulation results also indicated that CaO was a more preferable H2S sorbent than CaCO3 because syngas with an H-2/CO ratio closer to 2 can be produced and requires lower heat duty.