Use of different residues for high temperature desulphurisation of gasification gas

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H 2S 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 H 2S abatement. Thus, these materials could be a feasible and cheap alternative for H 2S 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 H 2S removal. Experiments were carried out in a fixed bed reactor at 700–900 °C, using a synthetic gas with 0.5 vol.% of H 2S (similar to that obtained by air gasification of sewage sludge). The highest H 2S 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.% H 2S after 2 h of experiment.