Use of different residues for high temperature desulphurisation of gasification gas

H2S is an important constraint for the final use of gas from coal or biomass gasification. Its content varies depending on the sulphur present in the feedstock raw material. In parallel, char and ash from biomass and coal gasification or combustion usually have significant amounts of metals, some of which have shown activity towards H2S abatement. Thus, these materials could be a feasible and cheap alternative for H2S removal, as they are generated inside the gasification process. This work evaluates the feasibility of using ash and char from several materials (lignite, bituminous coal and sewage sludge) for H2S removal. Experiments were carried out in a fixed bed reactor at 700–900 °C, using a synthetic gas with 0.5 vol.% of H2S (similar to that obtained by air gasification of sewage sludge).The highest H2S removal was achieved using lignite ash (at all temperatures) and bituminous coal (at T > 700 °C), obtaining, in these conditions, an outlet gas with less than 0.05 vol.% H2S after 2 h of experiment.

► Synthetic gasification gas with a 0.5 vol% of H2S desulfuration was studied. ► Char and ash from coal, lignite and sewage sludge and calcined dolomite were used at 700, 800 and 900 °C. ► Ash from coal and lignite show desulfurization efficiencies similar to calcined dolomite.