HC-SCR Catalyst Performance in Reducing NO_x Emissions from a Diesel Engine Running Heavy Duty Transient Test Cycles with Diesel Fuel and Ethanol as the Reductants

摘要

A unique silver/alumina selective catalytic reduction (SCR) catalyst which used hydrocarbons (HC-SCR) to reduce NO_x emissions was investigated. Diesel fuel or ethanol were used as the reductants to evaluate catalyst performance. Several full size 5.0L monolith 2.0 and 3.0 wt.% Ag_2O-Al_2O_3 catalysts were created. Testing was conducted using a 6.6L Duramax turbocharged heavy duty diesel engine. Dynamometer testing on the heavy duty FTP and SET 13 transient test cycles was conducted. The NO_x conversion efficiency was evaluated as a function of catalyst volume, inlet cone angle, hydrocarbon to NO_x ratio (HC:NO_x), and space velocity. Oxygen effects on the NO_x reaction and the HC slip past the HC-SCR catalyst were also determined. An FTIR was used to evaluate unregulated emissions. Testing on the heavy duty FTP and SET 13 test cycles, with diesel fuel as the reductant, resulted in a 60% and 65% NO_x conversion reduction respectively. With ethanol as the reductant the corresponding NO_x conversions were both 91%.