Hydrogen production by steam reforming (SR) of DME over Cu catalysts and de-NOx performance of a combined system of SR + LNT

This study was performed to develop a DME SR catalyst with high H2 selectivity using a heat source and water in the exhaust emissions of vehicles. The final goal of the research is to develop a combined system of SR + LNT for improving the de-NOx performance of the catalyst system in a DME engine. The scope of this research encompasses the optimization of the Cu concentration for the SR catalyst, evaluation of the NOx conversion efficiency of the LNT catalyst according to the kind of reductant (H2, CO, and DME), and evaluation of the de-NOx performance of the LNT catalyst and a combined system of SR + LNT. As a result of experiments concerning DME SR catalysts manufactured through the sol–gel method, the Cu20%/γ-Al2O3 catalyst showed the highest DME conversion and H2 selectivity. The combined system of SR + LNT using a Cu20%/γ-Al2O3 SR catalyst increased the NOx conversion by about 20% compared to the LNT catalyst alone at temperatures over 300 °C. In the combined system of SR + LNT, a supply of 1% of DME results in a higher NOx conversion than a supply of 0.75%, but results in NH3 slip and higher fuel consumption; therefore, supplying 0.75% of DME is favorable.