Insight into the performance of VOx-WOx/TiO2 catalysts modified by various cerium precursors: A combined study on synergistic NOx and chlorobenzene removal

Abstract

Cerium is widely used as a modifier to enhance the catalytic performance of the selective catalytic reduction (SCR) catalysts due to its exceptional low-temperature properties. However, the effects of different cerium precursors on catalytic performance remains unclear. In this study, VO x -WO x /TiO 2 catalysts are modified using Ce(NO 3 ) 3 ·6H 2 O (cata-N), CeO 2 (cata-O), and Ce(OH) 4 (cata-OH), and their synergistic removal of NO x and chlorobenzene (CB), as well as their resistance to water and sulfur poisoning, were systematically investigated. Among the tested catalysts, cata-N demonstrated superior CB (45.0–93.3 %) and NO x (31.9–90.37 %) removal efficiencies under synergistic conditions, along with excellent water resistance (T 90 = 193 °C with 5 % H 2 O). In contrast, cata-OH exhibited the highest sulfur resistance, maintaining a denitrification efficiency of 20 % after 10 h of sulfur exposure, compared to 9 % for cata-N and 8 % for cata-O. Characterization revealed that Ce(NO 3 ) 3 ·6H 2 O improved cerium dispersion, leading to enhanced the redox properties and acidity (especially Brønsted acid sites (BAS)) in cata-N. Density functional theory (DFT) calculations and In-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy ( In-situ DRIFTS) results revealed that the well-dispersed cerium atoms contributed additional BAS in the form of Ce–OH, while also forming Ti–O–Ce bonds. These Ti–O–Ce bonds facilitated the formation of Ti–OH on the TiO 2 surface. Ti–OH significantly enhanced the adsorption of NH 3 and CB, thereby promoting both the NH 3 -SCR and CB oxidation processes . This study offers new insights into the role of cerium precursors and provides a practical strategy for tuning BAS of catalysts in multiple pollutants removal.

Topics & Concepts