Study On Selective Oxidation Of Propane Into Acrylic Acid By Using Composite Metal Oxide Catalysts

Acrylic acid is a basic raw material and monomer for resin syntheses. The process toproduce acrylic acid by using propylene from refineries is relatively mature. However, theraw material, propylene, is expensive and the process to produce propylene by oxidation ofpropane is complex. Preparation of acrylic acid by direct oxidation of propane not onlyrepresents great advantages on the source and price of raw material but also simplify theproduction process greatly. In recent years, this rearch area had attracted extensive attensions.Metal oxide composite catalysts containing molybdenum, vanadium, tellurium and niobiumwas considered to be one of the best catalysts for preparation of acrylic acid by selectiveoxidation of propane. In this work, the preparation and catalytic performance of the metaloxide composites were investigated and discussed.First, X-ray diffraction, scanning electron microscopy and other modern characterizationtechniques were employed to study the effect of preparation method, drying temperature andpH on the structures, conversion ratio of propane and selectivity and yield of acrylic acid ofthe metal oxide composite catalysts. The experimental results showed that the MoVTeNboxide catalyst prepared by the solution mixing method, in which the drying temperature wasset at60°C and pH around4.0, presented excellent catalytic performance by activating thepropane effectively.Effect of the composition of the metal elements, atomic ratio, and the experimentalconditions such as preparation method, preparation process, drying temperature, pH etc.during the preparation of the catalysts on the catalytic perfomnce of the composite metaloxide catalysts were further discussed in this thesis. The experimental conditions forpreparation of the catalysts were optimized based on these results. In the catalysts preparedand evaluated, it was found that the four metal components, Mo, V, Te and Nb, played keyroles to improve the catalytic performance of the metal oxide composites. When the ratio ofMo, V, Te and Nb were set at1.0:0.3:0.23:0.12, the resulting catalyst showed the best catalyticperformance. The optimized experimental conditions for prepareation of the metal oxidecomposite catalysts were derived to be pH around4.0and dring temperature at60°C byusaing the solution mixing method. When the catalytic reaction temperature was set at400°C, the conversion ration of propane, yield and selectivlty of of acrylic acid were determindedto be50.12%,26.87%, and53.61%respectively.