Catalytic reduction of emissions from small-scale combustion of biofuels

There is a great potential for catalytic techniques, the emissions of primarily CO and unburnt hydrocarbons can be reduced and the emissions of NOx can indirectly be reduced. The aim of the project was to methodically indicate the requirements that both the catalyst and the stove must meet to enable the development of low emission stoves utilizing this technique. The project should also aim at the development of catalysts that meet these requirements and apply the technique on small-scale stoves. These appliances have been evaluated by experimental work, and conclusions drawn on the optimization of the technique. It has been verified experimentally that in a wood-fired stove a reduction of the CO-emissions of 60% can be achieved for the monolithic catalysts. This reduction could be achieved even without any optimization of the design. Experiments in small scale and under well controlled conditions have shown that almost 100% reduction of CO can be achieved. The parameters that limit the conversion over the catalyst have been identified as: Short residence time, Mass transport limitations caused by the large channel width, uneven temperature profile over the catalyst, Insufficient mixing before the catalyst. During the project is was shown that the emissions during the start-up phase could be reduced by preheating the catalyst. Minor alterations of the stove construction have also been made, resulting in in lower emissions before the catalyst. The result also show the need of an optimal integration of the catalyst in the stove 7 refs, 19 figs, 6 tabs