Simultaneous catalytic removal of NOx and diesel soot over Cu-containing hydrotalcite derived catalysts

Abstract

Copper-containing mixed oxides (CuAlO) were derived from hydrotalcites and prepared by co-precipitation and thermal evolution methods. The catalytic activity of the CuAlO was investigated for the simultaneous catalytic removal of NOx and diesel soot particulates by a temperature-programmed reaction (TPR) technique in a fixed-bed flow reactor. CuAlO showed good activity for the NOx-soot removal reaction under both tight and loose contact conditions. When the contact conditions between catalyst and soot changed from tight to loose, the ignition temperature (Ti) increased from 260°C to 314°C while the maximum conversion of NO to N2 (XN2-max) decreased from 40.4% to 29.2%. Soot content had no effect on the ignition temperature and all the Ti values were about 260°C for different soot content. With an increase in NO concentration or O2 concentration the Ti value decreased. X N2-max values were about 40% when the O2 concentration changed from 2.5% to 7.5%. The total flow rate had no effect on the T i values, while the XN2-max decreased from 40.4% to 21.6% when the total flow rate increased from 20 to 80 mL·min-1. Catalytic activity decreased when the catalyst was reused and this decrease may be related to an intermediate absorbed on the catalyst surface. © Editorial office of Acta Physico-Chimica Sinica.