SULFUR POISONING OF NICKEL-CATALYSTS IN CATALYTIC HOT GAS CLEANING CONDITIONS OF BIOMASS GASIFICATION

Biomass-derived gasification gas contains tar that can plug the particulate filters, and ammonia that forms nitrogen oxides when burned. The use of a catalytic gas purification unit before particulate filters to decompose tar and ammonia is a promising method to solve these problems. Sulphur poisoning studies of nickel catalyst were performed in fixed-bed reactors at 800 - 950 degrees C under 1 - 20 bar pressure with real and simulated gasification gas mixtures containing various amounts of H2S. The results indicated that the operation temperature had a great influence on the poisoning effect of sulphur. The higher the temperature the more sulphur the gas may contain without catalyst deactivation. The ammonia-decomposing activity declined due to sulphur more than the tar-decomposing activity. The catalyst was regenerated by removing H2S from the gas and the regeneration was enhanced by increasing the steam content ofthe gas.