The mechanism of Pd, K co-doping on Mg–Al hydrotalcite for simultaneous removal of diesel soot and NOx in SO2-containing atmosphere

Abstract

A Pd/K/MgAlO mixed oxide was obtained by coprecipitation. The effect of Pd, K co-doping on the structure and catalytic activity of the Mg–Al hydrotalcite in a high concentration of SO2 atmosphere was characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), Temperature-programmed reduction (H2-TPR), and the transient response method. Studied the reaction mechanism and action mechanism of the doped K and Pd with the polluted gas in the catalytic, and calculated the kinetic parameters of the catalytic reaction. Our results show that potassium was highly dispersed on the surface of Mg–Al hydrotalcite and that incorporating potassium into the catalyst resulted in smaller grains than those of the original catalyst. After potassium doping K, K+ cations substituted protons of the weakly basic OH on MgAlO to form Mg(Al)-O-K., and the formation of this new basic valence bond conducive to the combustion of diesel soot. The ignition temperature of soot decreased from 380 to 217 °C. Moreover, modification of this Mg–Al hydrotalcite catalyst with potassium and palladium significantly reduces the activation energy of the reaction which form CO2 and N2 and benefit the combustion of soot and removal of NOx.