Oxidative dehydrogenation of n-butane to butadiene over Bi-Ni-O/γ-alumina catalyst

Oxidative dehydrogenation of n-butane to 1,3-butadiene over Bi-Ni oxide/gamma-Al2O3 catalyst was studied with fixed bed/flow-type reactor at 400-500 degrees C. The gamma-Al2O3 support itself showed activity for oxidative dehydrogenation from n-butane to n-butenes as well as partial oxidation to CO. The role of Ni oxide on gamma-Al2O3 was confirmed that sole Ni oxide loading until 30 wt% Ni on gamma-Al2O3 resulted higher activity and selectivity to butadiene by diminishing partial oxidation related to,y-Al203 and enhancing conversion to butadiene. The concerted effect of Bi and Ni in Bi-Ni oxide/y-Al203 catalyst was confirmed with two methods: (1) partial or full substitution of Bi for 1/3, 2/3 and 3/3 Ni of 30 wt% Ni on gamma-Al2O3, and (2) various amounts of Bi addition to 20 wt% Ni on gamma-Al2O3. As for (1) Bi substitution, 10 wt% Bi-20 wt% Ni showed higher activity and selectivity than the others. As for (2) Bi addition, it until Bi/Ni = 0.82 (60 wff Bi-20 wt% Ni) lead to suppressed CO/H-2 production and improved conversion to butadiene. 30 wt% Bi-20 wt% Ni oxide/gamma-Al2O3 catalyst showing the highest butadiene selectivity of about 47% at 450 degrees C was used to confirm the relation between the state of oxygen and the reaction pathways by changing reaction condition factors, oxygen-to-butane ratio and temperature. It was revealed by catalyst characterization that the catalyst of Bi modified and Ni oxide highly loaded on gamma-Al2O3 has high activity and selectivity for oxidative dehydrogenation of n-butane to butadiene due to either an improved Ni dispersion and redox property or a couple of weak acidity and moderate basicity. (C) 2015 Elsevier B.V. All rights reserved.