Co-gasification of coal and wastes in a pilot-scale installation. 2: Effect of catalysts in syngas treatment to achieve sulphur and nitrogen compounds abatement

Coal mixed with different types of wastes was co-gasified in a pilot-scale installation. The syngas produced was hot treated in two catalytic fixed-bed reactors. In the first one, dolomite was used and in the second reactor, a nickel-based catalyst was employed. Two different grade coals were tested, Puertollano and Colombian. Puertollano coal had high ash and sulphur contents, 42.5% and 2.4%, respectively, while ash and sulphur contents of Colombian coal were, respectively, 12.7% and 0.9%. Pine, bagasse, RDF and PE were the wastes mixed with both coals. After dolomite fixed-bed reactor, H₂S and NH₃ contents in syngas were much lower than those of the gas leaving the gasifier. For most coal and waste blends, NH₃ reductions changed between 30% and 50% depending on feedstock nitrogen content, while H₂S reductions achieved values from 68% to 74%, also depending on H₂S concentration in syngas. After syngas had gone through the nickel-based catalyst, it presented H₂S and NH₃ contents that allowed its use in boilers and gas engines for most coal and waste blends. The overall syngas treatment led to H₂S and NH₃ reductions higher than 97%. For most experiments, final H₂S and NH₃ concentration in syngas were below 20 ppmv and 30 ppmv, respectively.