Alkali- and Sulfur-Resistant Tungsten-Based Catalysts for NO_x Emissions Control

Abstract

The development of catalysts with simultaneous resistance to alkalis and sulfur poisoning is of great importance for efficiently controlling NOx emissions using the selective catalytic reduction of NOx with NH3 (SCR), because the conventional V2O5/WO3-TiO2 catalysts often suffer severe deactivation by alkalis. Here, we support V2O5 on a hexagonal WO3 (HWO) to develop a V2O5/HWO catalyst, which has exceptional resistance to alkali and sulfur poisoning in the SCR reactions. A 350 μmol g(-1) K(+) loading and the presence of 1,300 mg m(-3) SO2 do not almost influence the SCR activity of the V2O5/HWO catalyst, and under the same conditions, the conventional V2O5/WO3-TiO2 catalysts completely lost the SCR activity within 4 h. The strong resistance to alkali and sulfur poisoning of the V2O5/HWO catalysts mainly originates from the hexagonal structure of the HWO. The HWO allows the V2O5 to be highly dispersed on the external surfaces for catalyzing the SCR reactions and has the relatively smooth surfaces and the size-suitable tunnels specifically for alkalis' diffusion and trapping. This work provides a useful strategy to develop SCR catalysts with exceptional resistance to alkali and sulfur poisoning for controlling NOx emissions from the stationary source and the mobile source.

Efficient NH3-SCR removal of NOx with highly ordered mesoporous WO3(χ)-CeO2 at low temperatures

“…As for commercial V 2 O 5 -WO 3 /TiO 2 , there was 73% removal efficient. The sulfur-poisoning of catalysts may be caused by the formation of thermally stable sulfate species, which deposited on catalysts’ surface and blocked catalytic sites [42,43]. However, after cutting off inlet SO 2 , the NO x conversion ratio of mesoporous WO 3 (1)-CeO 2 recovered to 93% after 3 h, and remained at 93%, showing that the mesoporous WO 3 (1)-CeO 2 had better reversible inhibition effect.…”

Optimizing Selective Catalytic Reduction of NO with NH3 on Fe2O3/WO3 via Redox‐Acid Synergy

“…developed Fe 1− x W x O δ catalysts with wide operating temperature windows by introducing W to Fe 2 O 3 . We recently reported that hexagonal WO 3 with abundant Brønsted acid sites had simultaneous resistance against SO 2 and alkalis in SCR ,. Therefore, hexagonal WO 3 should be an appealing support to make Fe 2 O 3 ‐based catalysts for real stack gas applications.…”

Rational Design of Alkali‐Resistant NO Reduction Catalysts using a Stable Hexagonal V‐Doped MoO3 Support for Alkali Trapping

“…Finally, we used the stable alkali‐resistant V‐HMoO support for developing SCR catalysts by loading active V 2 O 5 on V‐HMoO ,. SCR experiments were conducted to investigate the resistance against alkali poisoning.…”

“…In addition, we recently established an ion exchange‐coordinate model as a guide for developing alkali‐resistant SCR catalysts . For instance, hexagonal WO 3 with strong acidity and abundant tunnels as the alkali‐trapping sites (ATSs) has been used as a support for loading V 2 O 5 ,. Another work reported by Chen et al.…”