High temperature hydrogen sulfide adsorption on activated carbon I. Effects of gas composition and metal addition

Various types of activated carbon sorbents were evaluated for their ability to remove H2S from a simulated coal gas stream at a temperature of 550 deg rees C. The ability of activated carbon to remove H2S at elevated temperatu re was examined as a function of carbon surface chemistry (oxidation, therm al desorption, and metal addition), and gas composition. A sorbent prepared by steam activation, HNO3 oxidation and impregnated with Zn, and tested in a gas stream containing 0.5% H2S, 50% CO2 and 49.5% N-2, had the greatest H2S adsorption capacity. Addition of H-2, CO, and H2O to the inlet gas stre am reduced H2S breakthrough time and H2S adsorption capacity. A Zn impregna ted activated carbon, when tested using a simulated coal gas containing 0.5 % H2S, 49.5% N-2, 13% H-2, 8.5% H2O, 21% CO, and 7.5% CO2, had a breakthrou gh time of 75 min, which was less than 25 percent of the length of breakthr ough for screening experiments performed with a simplified gas mixture of 0 .5% H2S, 50% CO2, and 49.5% N-2. (C) 2000 Elsevier Science Ltd. All rights reserved.