Acid SAPO-34 Catalysts for Oxidative Dehydrogenation of ehane

Acid SAPO-34-based microporous catalysts with chabasite structure have been tested for the oxidative dehydrogenation of ethane in the temperature range 550-700degreesC. Pure acid and La/Na-containing samples were monitored and very interesting catalytic performances were achieved at 550-700degreesC (75-60% C2H4 selectivity and 5-30% ethane conversion) with respect to those reported for both acid zeolites and metal oxides. These performances correlated to the Bronsted acidity probed by FTIR spectroscopy and temperature-programmed desorption of NH3. The number of Bronsted acid sites located at the bridging hydroxyls (3626-3600 cm(-1)) in acidic SAPO-34 was higher than in La- and Na-containing samples, which showed also a larger amount of P-OH at framework defects. Lewis acidity induced by the presence of La and Na ions also influenced the reactivity of the SAPO-34-based catalysts.