SYNTHESIS OF CATALYSTS BASED ON Ni-Ti MIXED OXIDES FOR THE PRODUCTION OF ETHYLENE FROM CATALYTIC DEHYDROGENATION OF ETHANE

Abstract

Catalysts based on titanium doped nickel oxides Ni1-αTiα O with α from 0.01 to 0.05, were prepared by a controlled evaporationmethod at 550 °Cforselective oxidative dehydrogenation (ODH) of ethane to ethylene. The introduction of small amounts of Ti into the NiO lattice had noticeable effects on the nickel simple oxide properties, increasing the BET surface. In addition, it was observed a sustained depletion of crystallite size following XRD analysis, a generation of new acid sites, evaluated by NH3-TPD, a redistribution of reducible species to lower and higher temperatures studied from H2 -TPR profile and a depression of nonstoichiometric oxygen with the increasing composition of titanium detected by O2 -TPD. The catalytic tests were carried out under steady state conditions at a constant W/F of 0.48 g.s/ mL in order to evaluate the conversion and modifying W/F from 0.24 to 0.48 g.s/mL, to quantify the selectivity to ethylene. In all the Ni1-αTiαO catalysts, the catalytic tests revealed a positive doping effect of Ti in the performance of the samples, improving the ethane conversion and selectivity levels to ethylene, in comparison to the pure NiO. The sample Ni0.95Ti0.05O achieved the best selectivity to ethylene (77%) at a moderated ethane conversion of 35%, probably due to the increasing of the nucleophilic species of surface oxygen.