Application Of Oxide Catalysts Synthesized By Solid Reaction For Total Oxidation Of Toluene

VOCs are the main exhausts coming from the petrol-chemical plants and automobiles. Many countries have made strict effluent standards to control the discharge of VOCs. Catalytic combustion has been recognized as one of the most important technologies to destroy VOCs at low temperature. This method has many advantages such as low temperature required for combustion ignition, high energy efficiency, and avoiding the formation of toxic byproducts. Toluene is the simplest, most volatile and least toxic of the aromatic hydrocarbons; it has been used as a model to develop catalysts with potential to effectively destroy aromatic hydrocarbons.Employed catalysts for catalytic combustion are mainly noble metals which are very active at low temperature; however, their use is limited due to the high price, low thermal stability and tendency to poisoning. On the other hand, transition metal oxides are a suitable alternative because of their higher thermal stability and lower price.The non-solvent solid reaction based on mechanochemical activation has been previously established, which was an effective and easily-scalable technique for a nitrate-free preparation of nanostructured metal oxide catalysts. In the present work we report a simple and green solid reaction procedure to synthesis nanocrystalline CeO2、Co3O4、Mn2O3. The catalysts were applied for total oxidation of toluene, and exhibited high activity, high stability and high selectivity to CO2 and H2O. Complete conversion has been achieved at reaction temperatures as low as 230℃. The influence of calcination temperature on structure and chemical characteristics was studied. Variation of calcination temperature of oxalic precursors resulted in differences in surface area, reducibility, morphology and crystallite size of the oxide catalysts, and hence differences in catalytic performance. It was found that the combination of high surface area, small crystallite size and high oxygen defect concentration was related to the activity of the oxide catalysts for the total oxidation of toluene.We also prepared nanocrystalline copper-cobalt spinel oxides through high energy ball milling procedure. The catalysts are exceptionally active for total oxidation of toluene. The superior activity of the present copper-cobalt spinel catalyst has been attributed to the formation of highly strained spinel nanocrystals as a consequence of the mechanochemical activation during the milling process. The prominent lattice distortion induced by high energy ball milling is suggested to play a key role in creating and maintaining a high density of surface defects, which leads to highly activity and stability of the spinel catalyst.