This review aims to give a general overview of the recent use of tungsten-based catalysts for wide environmental applications, with first some useful background information about tungsten oxides. Tungsten oxide materials exhibit suitable behaviors for surface reactions and catalysis such as acidic properties (mainly Brønsted sites), redox and adsorption properties (due to the presence of oxygen vacancies) and a photostimulation response under visible light (2.6–2.8 eV bandgap). Depending on the operating condition of the catalytic process, each of these behaviors is tunable by controlling structure and morphology (e.g., nanoplates, nanosheets, nanorods, nanowires, nanomesh, microflowers, hollow nanospheres) and/or interactions with other compounds such as conductors (carbon), semiconductors or other oxides (e.g., TiO₂) and precious metals. WO_x particles can be also dispersed on high specific surface area supports. Based on these behaviors, WO₃-based catalysts were developed for numerous environmental applications. This review is divided into five main parts: structure of tungsten-based catalysts, acidity of supported tungsten oxide catalysts, WO₃ catalysts for DeNO_x applications, total oxidation of volatile organic compounds in gas phase and gas sensors and pollutant remediation in liquid phase (photocatalysis).

WO₃/Ce_xZr_1–xO₂ materials were evaluated as a possible NH₃-selective catalytic reduction (SCR) active catalyst in a NO_x storage reduction (NSR) + SCR combined system. The effect of the support composition was investigated at a constant WO₃ loading (9.1 wt % of WO₃). The impact of WO₃ promotion over textural, structural, acid–base, and redox properties of SCR samples was characterized by means of nitrogen adsorption–desorption isotherms, XRD, NO_x storage capacity, NH₃ temperature programmed desporption, pyridine adsorption followed by FTIR, and H₂-TPR. Catalytic activities in NH₃-SCR and NH₃-SCO reactions as well as corresponding kinetics parameters are also discussed. All WO₃/Ce–Zr materials are active and fully selective in N₂ for NO_x reduction by NH₃ and ammonia oxidation by O₂. For the SCR reaction, the rate of NO conversion is found approximately half-order with respect to NO, and negative to nearly zero-order with respect to NH₃. Tungstated ceria–zirconia materials were then associated downstream with a model Pt–Ba/Al NSR catalyst. Whatever the WO₃–Ce/Zr catalyst, the global NO_x conversion and N₂ yield are significantly enhanced by the addition of the SCR catalyst. Special attention is paid to the influence of the ceria content of the SCR catalyst on the ammonia reactivity in the combined NSR + SCR system. It is demonstrated that NH₃ produced during the regeneration step of Pt–Ba/Al catalyst can react either with NO_x (NH₃-SCR) or with O₂ (NH₃-SCO). This reactivity depends both on the Ce/Zr ratio of support and on the temperature. Finally, it is demonstrated that at high temperature (i.e., 400 °C), the strength of the acid sites of the WO₃–Ce/Zr catalysts is not sufficient to ensure no ammonia slip.