WO3 and Ionic Liquids: A Synergic Pair for Pollutant Gas Sensing and Desulfurization

Abstract

This review deals with the notable results obtained by the synergy between ionic liquids (ILs) and WO3 in the field of pollutant gas sensing and sulfur removal pretreatment of fuels. Starting from the known characteristics of tungsten trioxide as catalytic material, many authors have proposed the use of ionic liquids in order to both direct WO3 production towards controllable nanostructures (nanorods, nanospheres, etc.) and to modify the metal oxide structure (incorporating ILs) in order to increase the gas adsorption ability and, thus, the catalytic efficiency. Moreover, ionic liquids are able to highly disperse WO3 in composites, thus enhancing the contact surface and the catalytic ability of WO3 in both hydrodesulfurization (HDS) and oxidative desulfurization (ODS) of liquid fuels. In particular, the use of ILs in composite synthesis can direct the hydrogenation process (HDS) towards sulfur compounds rather than towards olefins, thus preserving the octane number of the fuel while highly reducing the sulfur content and, thus, the possibility of air pollution with sulfur oxides. A similar performance enhancement was obtained in ODS, where the high dispersion of WO3 (due to the use of ILs during the synthesis) allows for noteworthy results at very low temperatures (50 °C).

Recent Advances in Imidazolium-Based Dicationic Ionic Liquids as Organocatalysts: A Mini-Review

“…As an example, graphene oxide was frequently used as an ionic liquid support for many applications [ 39 , 40 ].…”

Review—Recent Development of WO3 for Toxic Gas Sensors Applications

“…Whereas the addition of carbon types and single conductive polymers on WO 3 -based sensors play a role in the process of improving sensing performance through a synergetic effect that allows reinforcement in the adsorption and desorption process of gas molecules. [217][218][219] As we have explained in the first paragraph, that under certain conditions, a WO 3 based toxic gas sensor can exhibit electrical properties identical to that of a semiconductor p-type. This can occur when the other materials that are mixed either homogeneously or heterogeneously are p-type semiconductors, thus forming a p-n composite sensor.…”

Metal Oxides

“…The review paper from D'Anna et al [3] deals with the notable synthesis of WO 3 (films and nanostructures) in ionic liquids (ILs). The synergy between ILs and metal oxides has been proposed recently to both direct oxides' production towards controllable nanostructures (nanorods, nanospheres, core-shell nanostructures, etc.)…”