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.