Optimizing Both Catalyst Preparation and Catalytic Behaviour for the Oxidative Dehydrogenation of Ethane of Ni–Sn–O Catalysts

Bulk Ni–Sn–O catalysts have been synthesized, tested in the oxidative dehydrogenation of ethane and characterized by several physicochemical techniques. The catalysts have been prepared by evaporation of the corresponding salts using several additives in the synthesis gel, i.e. ammonium hydroxide, nitric acid, glyoxylic acid or oxalic acid, in the synthesis gel. The catalysts were finally calcined at 500 °C in air. Important changes in the catalytic behaviour have been observed depending on the additive. In fact, an important improvement in the catalytic performance is observed especially when some additives, such as glyoxylic or oxalic acid, are used. Thus the productivity to ethylene multiplies by 6 compared to the reference Ni–Sn–O catalyst if appropriate templates are used, and this is the result of an improvement in both the catalytic activity and the selectivity to ethylene. This improved performance has been explained in terms of the decrease of the crystallite size (and the increase in the surface area of catalyst) as well as the modification of the lattice parameter of nickel oxide.