Co-gasification of coal and wastes in a pilot-scale installation 1: Effect of catalysts in syngas treatment to achieve tar abatement

Co-gasification of poor quality coals mixed with wastes has the advantage of diversifying energy resources and of decreasing the dependency on imported fossil fuels. However, the use of wastes like plastics increased the production of tar and gaseous hydrocarbons. Although, the correct adjustment of gasification experimental conditions, like temperature and air flow, may lead to some reduction of undesirable compounds, this procedure is not usually enough to accomplish effective reductions of tar and hydrocarbons, thus obliging to the use of further gas treatment. Co-gasification studies were undertaken in a pilot-scale installation. The syngas produced, after going through a cyclone to decrease particulates content, was further treated in two catalytic fixed bed reactors. In the first fixed bed reactor was used a low cost catalyst, like dolomite, to reduce H2S content in the gas and also to promote some tar destruction. In the second fixed bed reactor, Ni based catalysts were employed to achieve effective reduction of tar and other undesirable compounds. After the second fixed bed reactor, H2 content was much higher than that of the gas leaving the gasifier, values higher than 50% were obtained, while gaseous hydrocarbons contents were much lower, particularly CnHm contents were quite low, usually below the detection limit of the method used. The presence of tar was never detected after the second fixed bed reactor.