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).
Highlights
Tungsten trioxide (WO3 ) is a n-type semiconductor widely investigated both in its doped and undoped forms, in powders, films and nanostructures, because of its good gas sensing, antibacterial and antimicrobial properties, its pH sensitivity, its photocatalytic activity for water-splitting, etc
The synergic effect of WO3 and ionic liquids in gas sensing and desulfurization reactions has been only recently studied, and this can be attributed to the ability of ILs to dissolve inorganic compounds and to the solubility of water and permeability of some gases in certain ionic liquids, allowing the concentration of analytes on the surface of the sensor, while lowering the negative effect of high levels of humidity
ILs were demonstrated to be able to enhance the ability of tungsten trioxide in polluting gas sensing and in desulfurization processes, and the increasing number tungsten trioxide in polluting gas sensing and in desulfurization processes, and the increasing of publications on this topic gives an idea of future developments
Summary
Tungsten trioxide (WO3 ) is a n-type semiconductor widely investigated both in its doped and undoped forms, in powders, films and nanostructures, because of its good gas sensing, antibacterial and antimicrobial properties, its pH sensitivity, its photocatalytic activity for water-splitting, etc. In WO3 powders, doped with H, Na, Li or other impurity atoms or in WO3 thin film form, the cubic c-WO3 phase occurs [18,19]. The cubic perovskite-like structure is shown in Figure 1 and consists of corner sharing of regular octahedra with oxygen atoms at the corners and tungsten atoms at the center of each octahedron. The semiconductors is due to the resistivity changes in the the presence of the adsorbed gas. The depth of the space-charge layer is function of the surface adsorbates and oxygen adsorbates and intrinsic electron concentration in the bulk.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
