Vibrational spectroscopic studies on CO adsorption,NO adsorption CO + NO reaction on Pd model catalysts

摘要

CO adsorption,NO adsorption and CO + NO reaction on various Pd model catalysts have been studied using vibrational spectroscopy from ultrahigh vacuum (UHV) up to elevated pressures (~ 1 bar) and the kinetics of the reaction compared with the conventional high surface area Pd/y-Al_2O_3 catalysts.The structure sensitivity of the CO + NO reaction on different Pd surfaces is explained using Pd(lll),Pd(lOO) single crystals and planar Pd/ SiO_2/Mo(l 10),Pd/SiO_2/Mo(l 12),Pd/Al_2O_3/Ta(l 10) supported model catalysts by emphasizing the particle size/ morphology effects and particle-support interactions.A reaction intermediate,isocyanate (-NCO),is detected via in situ vibrational spectroscopy at elevated pressures on Pd(l 11) single crystal surface and the significance of this reaction intermediate on the improvement of the catalytic NO_x removal is discussed.