Halogen containing VOCs, oxidation

Catalytic Oxidization. A principal technology for control of exhaust gas pollutants is the catalyzed conversion of these substances into innocuous chemical species, such as water and carbon dioxide. This is typically a thermally activated process commonly called catalytic oxidation, and is a proven method for reducing VOC concentrations to the levels mandated by the CAAA (see Catalysis). Catalytic oxidation is also used for treatment of industrial exhausts containing halogenated compounds. 

An efficient, low temperature oxidation catalyst was developed based on highly disperse metal catalyst on nanostructured Ti02 support. Addition of dopants inhibits metal sintering and prevents catalyst deactivation. The nanostructured catalyst was formulated to tolerate common poisons found in environments such as halogen- and sulfur-containing compounds. The nanocatalyst is capable of oxidizing carbon monoxide and common VOCs to carbon dioxide and water at near ambient temperatures (25-50 °C). 

In this work we have studied two commercial oxide-based catalysts with a variety of feeds containing hydrocarbons, chlorocarbons, and mixtures of the two. The experiments deal primarially with oxidation at constant total conversion (> 99%) over extended periods of time, and much data are presented as the temperature-required vs time-on-stream to maintain the set conversion level [4]. Hydrocarbon oxidation has, of course, been studied for many years. The total oxidation of halogenated VOC s is, though, a relatively new area [5,6] ... 

VOCs, such as short-chain alkanes and aromatics, and undoubtedly advances in terms of activity and stability have been achieved. Scope still exists to develop more active and stable catalysts for the total oxidation of more demanding VOCs, such as halogenated compounds and those containing heteroatoms like sulfur. There is also significant potential to improve our understanding of the catalysis at a molecular level and this endeavour should help to develop better total oxidation catalysts, and Impact on other areas like selective oxidation. 

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