Poisoning effects of lead species on the V2O5‐WO3/TiO2 type NH3‐selective catalytic reduction catalyst

Abstract

AbstractHeavy metal Pb is an inevitable ingredient of coal‐fired flue gas and has been proven to be a source of inhibiting effect on the selective catalytic reduction (SCR) catalyst. In this paper, two types of Pb‐poisoned catalyst, prepared by the incipient wetness impregnation and solid diffusion methods, are studied to unveil the poisoning effects of lead species on the V2O5‐WO3/TiO2 catalyst. The activity test results showed that lead species loaded by the incipient wetness impregnation method exhibited a significant inhibiting effect on the denitrification efficiency of the catalyst although a negligible activity loss was observed on the samples from the solid diffusion method. Characterizations of fresh and Pb‐poisoned catalysts from incipient wetness impregnation method were applied using comprehensive techniques such as X‐Ray diffraction (XRD), field emission scanning electron microscopy (FE‐SEM), X‐ray fluorescence (XRF), NH3‐temperature programmed desorption (NH3‐TPD), X‐Ray photoelectron spectroscopy (XPS), and so forth. The analytical results indicated that a phase transformation occurred in tungsten species and the amorphous WO3 converted into PbWO4, causing the accumulation and valence imbalance of active vanadium phase, which further decreased the surface acidity and activity of the V2O5‐WO3/TiO2 catalyst.