Removal of hydrogen sulfide from a steam-hydrogasifier product gas by zinc oxide sorbent: Effect of non-steam gas components

Abstract Removal of H 2 S from a steam-hydrogasifier product gas was studied at 636 K and 1 atm using a commercially available zinc oxide sorbent in a packed-bed reactor. A mixture gas containing 22% CH 4 , 18.7% H 2 , 8.8% CO and 5.5% CO 2 (non-steam components subtotaling to 55%) balanced with steam was used to simulate the steam-hydrogasifier product gas. Sorbent particles of 150–250 μm size were used to eliminate the effect of intraparticle mass transfer limitation. Experiments were conducted to monitor H 2 S breakthrough of reactor effluent stream for operation parameters such as space velocity and inlet H 2 S concentration. With space velocity varied from 6000 to 8000 to 12,000 h −1 for inlet H 2 S concentration in the range of 100–800 ppmv, sulfur capture capacity of the sorbent ( S cap ) for 2 ppmv H 2 S breakthrough did not change notably, indicating that, for each inlet H 2 S concentration tested, sorbent utilization for sulfur removal was not affected by the space velocity. Meanwhile, for each space velocity tested, S cap increased monotonically as the inlet H 2 S concentration increased from 100 to 500 to 800 ppmv, which is opposite to the result observed for the mixture gas devoid of CH 4 , H 2 , CO and CO 2 . As the overall content of these non-steam components of the simulation gas was halved for each inlet H 2 S concentration tested at 8000 h −1 space velocity, S cap for non-steam gas components of 27.5% content corresponded approximately to the median value of those for the non-steam gas components of 55% and 0% content, suggestive of linear dependency of S cap upon the content of the non-steam components for the inlet H 2 S concentration tested.