Oxidative dehydrogenation of ethane over Dy2O3/MgO supported LiCl containing eutectic chloride catalysts

Abstract

The catalytic oxidative dehydrogenation of ethane with alkali and alkaline earth metal chloride modified LiCl supported on Dy2O3/MgO (MD) was studied. Eutectic mixtures of alkali and alkaline earth metal chloride with LiCl are formed on the support surface decreasing so the melting point of pure LiCl to temperatures as low as 366°C (Li-K-MD). All samples had weak basicity decreasing in the order: Li-K-MD<Li-Sr-MD Li-Ba-MD<Li-Na-MD<Li-MD. Physisorbed and chemisorbed CO2 species are identified for all materials studied by in situ IR spectroscopy. Bidentate carbonate species are the most abundant on Li-MD, while on modified samples bi- and unidentate carbonate species exist. The catalyst activity increases with decreasing basicity. Catalyst selectivity increases with increasing reaction temperature and is constant above a threshold temperature. The maximum ethene selectivity is directly correlated with the melting point of the eutectic melt on the catalyst support.