Study In The N-Butane Oxidative Dehydrogenation Reaction Over Vanadium-based Oxide Catalysts

The selective oxidation of light saturated hydrocarbons into more valuable unsaturated hydrocarbons and organic compounds-containing oxygen has become one of the challenging research subjects in heterogeneous catalysts. As a vital reaction of the selective oxidation, the oxidative dehydrogenation (ODH) of n-butane is becoming increasingly important not only in academic research but also in industrial utilization.Four different VMgO catalysts containing thirty percent of V2O5 in weight have been studied in the n-butane oxidative dehydrogenation reaction and characterized by XRD and FT-IR. The VMgO catalyst prepared by impregnation method using a MgO as support, which had been obtained by treating a commercial MgO in refluxing distilled water followed by a calcination at 500 ℃, showed higher activity and selectivity for the n-butane oxidative dehydrogenation reaction, which are related to more Mg-orthovanadate (Mg3V2O8) and less Mg2V2O7 and V2O5 species contained in the catalyst. The VMgO catalyst was further modified with nickel component. By doping the VMgO catalyst with Ni component at Ni/V ratio of 0.3 in moles, the selectivity to butenes and butadiene in the n-butane oxidative dehydrogenation reaction was increased to 51.2 % at the n-butane conversion of 20.3 % from 46.7 % at the n-butane conversion of 18.3 %. The XRD and FT-IR characterization results indicate that the Ni-VMgO catalyst contains more Mg3V2Os, and less Mg2V2O7 species than the VMgO catalyst. The VMgO catalyst was modified with boron or bismuth component. The result indicates the capacity of B-VMgO catalyst was better than VMgO catalyst. However, the Bi- VMgO catalyst lost activity with adding bismuth.The various V/TiO2 catalysts were prepared and investigation of catalyststhat are effective for the oxidative dehydrogenation of n-butane at low temperatures. Although the. V/TiO2 catalysts can active o-butane at quite low temperature (~ 260 ℃), but overoxidation products, such as CO, CO2, are the main products. The V/TiO2 catalyst was modified with other metal elements or P component. The result indicated that the performance of V/TiO2 catalyst was improved with adding some metal element, such as Mg, Zn.