Selective catalytic reduction of NO x with NH 3 over cerium–tungsten–titanium mixed oxide catalyst: Synergistic promotional effect of H 2 O 2 and Ce 4

• Published in: Journal of materials research 2020-08, Vol.35 (16), p.2218-2229
• Main Authors: Xiong, Zhi-bo, Qu, Xiao-ke, Du, Yan-ping, Li, Cheng-xu, Liu, Jing, Lu, Wei, Wu, Shui-mu
• Format: Article
• Language: English
• ISSN: 0884-2914; 2044-5326
• DOI: 10.1557/jmr.2020.203

A highly active catalyst of cerium–tungsten–titanium mixed oxide was synthesized by introducing Ce 4+ and H 2 O 2 in the base sample of Ce 20 W 10 Ti 100 O z –Ce 3+ . As a consequence, the NH 3 -SCR activity of Ce 20 W 10 Ti 100 O z –Ce 3+ is significantly improved as the additives of Ce 4+ and H 2 O 2 enlarge the Brunauer–Emmett–Teller (BET) surface area by refining its pore size. Meanwhile, the introduction of Ce 4+ increases the Lewis acid sites of Ce 20 W 10 Ti 100 O z –Ce 3+ and decreases its low-temperature Brønsted acid sites. The further addition of H 2 O 2 improves the Brønsted acid sites and dispersion of cerium/tungsten species, and thereby enhances the concentrations of the adsorbed oxygen (O α ) and the adsorbed oxygen $\lpar {\rm {O}^{\prime}}_{\rm \alpha} \rpar$ due to the activation of chemisorbed water on the surface of the catalyst. The addition of Ce 4+ and H 2 O 2 shows a synergistic promotional effect, which is due to the largest BET surface area and the highest concentrations of O α or/and ${\rm {O}^{\prime}}_{\rm \alpha}$ . Ce 20 W 10 Ti 100 O z –Ce 3+ :Ce 4+ = 17.5:2.5 + H 2 O 2 exhibits the highest catalytic activity compared with the conventional ones (Fig. 5).