Study On Redox Performance Of Complex Metal Oxides

Complex mental oxides are important catalysts during the selective oxidation andammoxidation process of hydrocarbon. They have played an important role in the heterogeneouscatalysis field for long because of their excellent properties, such as excellent redox property,thermal stability and mechanical intensity, strong acidity-basicity. The understanding on reactionmechanism of complex mental oxides is very limited even though they have been widely used.Selective catalytic oxidation of propane has been a problem from the industrial point ofview because it is less expensive but difficult to functionalize. It is promising to convert thepropane into acrylic acid and complex mental oxides have been proposed as the most active andselective catalysts in the oxidation of propane to acrylic acid. Complex mental oxides canactivate both the oxygen and the alkane through the redox reaction of itself. Catalysis of thecomplex mental oxides can be greatly effected by it's redox property.In the present work, a significant study on the oxidation performance and re-oxidationperformance of Mo-V-Te-Nb-O catalyst was carried out using a pulse reactor in which theoxidation of propane and the reoxidation of catalyst were taken place alternatively. theconfiguration of the catalyst was also charactered. It is confirmed that propane reacts with latticeoxygen of Mo-V-Te-Nb-O catalyst to form AA under the condition of no molecule oxygen. Thequantity and activity of the oxygen species will be improved through the increasing ofpre-oxidation time and enhancing of pre-oxidation temperature, the surface configuration of thecatalyst will be improved with the presence of water in regeneration atmosphere and theselectivity of the product can also be heightened. The results showed that the consuming speed ofthe oxygen species that helping to the oxidation dehydrogenation of propane is more prompt thanthe oxygen species that selectively oxidation to acrylic acid after the study of the catalyst'sstoring oxygen using different material propane and propylene. Different oxygen species has it'sown role in the catalytic process. The desorption behaviour of ammonia on the catalysts wasstudied by means of TPD. One key desorption peak was found at the temperature about 200 ℃and an obvious desorption peak was found on the spent catalyst at the high temperature region.