Revisiting the Behaviour of Vanadia-Based Catalysts in the Abatement of (Chloro)-Aromatic Pollutants: Towards an Integrated Understanding

Abstract

For several years, the authors study VO x /TiO 2 catalytic formulations in the context of the oxidative abatement of aromatics, possibly chlorinated, from polluted air. This paper revisits their main findings and understandings. Although VO x /TiO 2 catalysts, when upgraded with Mo or W oxides, are already used in industrial applications, it is shown that the systematic investigation (i) of the reasons why optimized synthesis and formulations are indeed efficient, (ii) of the nature of the sites responsible for the adsorption of the pollutants and their catalytic transformation, and (iii) of the corresponding mechanisms, is a valuable approach to identify guidelines and strategies for further improving the catalysts. The origin of the beneficial effects brought by WO x and MoO x to VO x /TiO 2 , and by the use of a sulphated titania support, is addressed, as well as the impact on the catalysts behaviour and performances of molecules inevitably present in a combustion exhaust gas, like CO and NO x co-pollutants and water. The behaviours of a chloroaromatic molecule, like chlorobenzene, and an oxygen containing-heterocyclic molecule, like furan and dimethylfuran, are then compared and discussed in the debate of their selection as representative model compounds for the catalytic abatement of dioxins. In this context, it is shown that strategies developed to improve the performances of VO x /TiO 2 formulations to abate Cl-aromatics, could be detrimental for cyclic molecules containing O-heteroatom, as entire dioxins. Finally, an integrated view of the catalytic process is presented by envisaging the case of a complex mixture, closer to the real application of gaseous effluent cleaning.

Catalytic decomposition of gaseous PCDD/Fs over V2O5/TiO2-CNTs catalyst: Effect of NO and NH3 addition

“…Meanwhile, the catalyst is participated in the two reactions and converts between V 5þ O x and V 4þ O x (Roy et al, 2009;Delaigle et al, 2009). Considering the similarity, NOeNH 3 reaction and PCDD/Fs catalytic decomposition may interfere with each other when NO, NH 3 and PCDD/Fs moleculars are simultaneously exposed to the catalyst.…”

Catalytic Oxidation of Chlorobenzene over Ruthenium-Ceria Bimetallic Catalysts

“…In comparison to other VOCs, chlorinated volatile organic compounds (CVOCs) are more toxic and difficult to remove from the flue gas [3][4][5][6]. Many strategies have been developed for CVOC abatement, including incineration, catalytic oxidation, and adsorption-based techniques [7][8][9].…”

Electrospinning synthesis of vanadium–TiO2–carbon composite nanofibrous membranes as effective catalysts for the complete oxidation of low-concentration acetone

“…Transition metal-based catalysts, such as those containing cobalt [7], manganese [8], and vanadium [9], became appealing because of their low cost and abundance [10]. Among these catalysts, vanadium-based ones are believed to be good candidates for VOC oxidation [11,12].…”