Bimetallic Bi-Ni oxides over carbide supports for oxidative dehydrogenation of n-butane: Experimental and kinetic modelling

n-butane oxidative dehydrogenation was studied over Bi-Ni/TiC, Bi-Ni/SiC, Bi-Ni/Silicalite-1, and unsupported Bi-Ni catalyst. The co-impregnation technique was followed, with fixed 0.30 and 0.20 g/g for Bi and Ni respectively. The physico-chemical properties were measured by means of BET, XRD, CO₂/NH₃-TPD, and H₂-TPR techniques. The catalytic test results revealed that bimetallic Bi-Ni/TiC catalyst exhibited the highest n-butane conversion of 16.6% with dehydrogenation selectivity of 83.7%. As regards Bi-Ni/TiC catalyst, the main operating parameters including O₂/n-C₄H₁₀ feed ratio, space velocity, and reaction temperature were varied. The Bi-Ni/TiC catalyst showed adequate stability for a 10-hr time on stream test. The high performance of Bi-Ni-O/TiC catalyst is attributed to the synergistic role of reducibility, presence of strong basic sites and weak acidic sites, and an increased metal species dispersion over the TiC support. A kinetic study of n-butane oxidative dehydrogenation was carried out. The apparent activation energy for formation of butadiene was estimated to be the lowest, while the highest activation energy is required for the undesirable cracking reaction.