Reduction of NO_x by plasma-facilitated catalysis over in-doped gamma-alumina

摘要

Sol-gel derived gamma-alumina and its 2.5 wt% indium doped derivative were examined as plasma-activated catalysts for reduction of NO_x in model lean burn exhaust.The extent of promotional effect on catalysis due to indium doping depends both on the specialition of hydrocarbon used as a reducing agent in addition to reaction temperature.In/gamma-alumina catalysts were tested with either hydrocarbons (propane,propene,methanol,ethanol,1-propanol,2-propanol,acetaldehyde,isooctane) at a C_1:N ratio of 12 to investigate the effect of hydrocarbon structure and chemistry on activity for plasma-enhanced catalysis.The functionality,the location of the functional group,as well as the molecular size all proved to have an impact on the ability of the hydrocarbon to participate in NO_x reduction chemistry.Plasma assist provided benefits at moderate temperature,but NO_x reduction was dominated by thermal activity (no plasma required) at high temperature.The effect of aging on catalyst performance was also examined,and the most negative impact on thermal activity was observed at moderate temperatures.Plasma assist resulted in recovery of nearly all activity for most of the oxygenated hydrocarbons examined.At high temperature,aging had negligible impact on catalyst performance with the exception of catalytic reduction with methanol.