Venkata Dasireddy

Chromium molybdate supported on alumina catalyst was tested over oxidative dehydrogenation of n-butane with different oxidants like O2, CO2 and N2O. Effect of oxygen nature and oxygen mobility of CrMoO4/Al2O3 catalysts on the catalytic performance in the oxidative dehydrogenation of n-butane was investigated. Experimental results revealed that the large oxygen capacity and a high oxygen mobility of the catalyst were favourable for obtaining high catalytic activity during the catalytic reaction in the oxidative dehydrogenation of n-butane. The highest selectivity to 1,3-butadiene (BD) was achieved at an oxidant to butane molar ratio of 1.5 at a temperature of 350 °C. BD showed a low selectivity while the selectivity to carbon oxide increases, which may be due to the increasing the coke deposition at lower oxygen to butane molar ratios. In the presence of CO2, n-butane make significant amount of hydrogen and CO due to CO2 reforming reaction. The peak position in the low temperature region of TPRO profiles could be correlated to the selectivity of 1,3-butadiene and suggests the N2O had a stronger adsorption capability on the surface of the catalyst and it facilitates an easier migration of lattice oxygen from bulk to surface to complete the oxidation process. N2O which generates radical oxygen species Oα- which is named as α-oxygen gave significant amounts of BD, but no oxygenated products over CrMoO4/Al2O3 catalyst transition metal oxides. A partial oxidation of the catalyst was observed under N2O and CO2 atmospheres.

Keywords: butadiene, oxygen mobility and capacity, O2, CO2, N2O and CrMoO4/Al2O3 catalyst