Temperature program adsorption of hydrogen sulfide by NaOH-impregnated activated carbons for hot fuel gas purification

Natural gas, biogas and synthesis gas from coal gasification contain hydrogen sulfide (H 2 S) that is toxic and strong odorous for human. It is high corrosive for engine. Among various methods for H 2 S removal, the adsorption by activated carbon is known as an efficient process for low concentration H 2 S removal. Moreover, activated carbon is not only inexpensive but also produces from agricultural waste in Thailand. The objective of this work is for upgrading the commercial-grade activated carbon by sodium hydroxide (NaOH) impregnation and the combination of steam activation and NaOH impregnation. The aim of upgrading is to improve the performance of H 2 S removal from fuel gases. The commercial and NaOH-impregnated activated carbons were tested by the temperature program adsorption of H 2 S at 30 °C and 550 °C. The results showed that the adsorption capacities of the NaOH-impregnated activated carbons are significantly higher than the commercial activated carbon (in the range of 2–21 times higher depending on the temperature of adsorption). At high temperature of adsorption, the adsorption capacity of the NaOH-impregnated activated carbon was 30.10 mg of H 2 S per gram of activated carbon. It can be concluded that the upgraded activated carbons is applicable for hot fuel gas purification. The concentration of H 2 S comes out at the outlet gas after treatment by the upgraded materials was almost 0 ppmv, which is safe for utilizing in fuel cell system and power engine.