Exhaust gas catalysts for heavy-duty vehicles fuelled by alcohol or biogas

摘要

The long-term objective for the project is to develop tailor-made exhaust gas catalysts for heavy-duty ethanol fuelled diesel vehicles operating in urban traffic. Due to special problems, related to emissions of unregulated compounds emanating from ethanol fuelled buses in Swedish fleet tests, a catalyst research programme has been initiated. The engineering target was to achieve a light-off temperature (T(sub 50)) for ethanol conversion below 110 deg C and a selectivity for total oxidation over 90 %. In this report results from laboratory-reactor tests are described. The results indicate that by combining two different precious metals both activity and selectivity can be positively affected compared to the properties of the corresponding mono metallic catalysts. The best results show a light-off temperature for ethanol conversion below 100 deg C. The base metal oxides were more selective for total oxidation than the corresponding precious metal catalysts. The results also indicate a considerable interaction between support and active material which affects the product distribution in catalytic oxidation of ethanol. At temperatures below 250 deg C the by-product formation can be quite high and the major by-product is acetaldehyde. The metal support interaction also has a certain influence on the oxidation of NO to NO(sub 2). The results show that the NO(sub 2) formation can be suppressed without considerably affecting the activity of the catalyst. This report also includes a preliminary life cycle analysis (LCA) and life cycle cost (LCC) estimate for exhaust gas catalysts intended for heavy-duty ethanol vehicles in urban traffic. 22 refs, numerous figs and tabs