Canadian Journal of Chemical Engineering, Vol.96, No.6, 1367-1376, 2018
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 H-2-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% (1,3-butadiene and butenes selectivity of 50.7 % and 33% respectively). As regards Bi-Ni/TiC catalyst, the main operating parameters including O-2/n-C4H10 feed ratio, space velocity, and reaction temperature were varied. The Bi-Ni/TiC catalyst showed adequate stability for a 10 h 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 (15 kJ/mol), while the highest activation energy (105 kJ/mol) is required for the undesirable cracking reaction.