Acid SAPO-34 catalysts for oxidative dehydrogenation of ethane

Acid SAPO-34-based microporous catalysts with chabasite structure have been tested for the oxidative dehydrogenation of ethane in the temperature range 550-700°C. Pure acid and La/Na-containing samples were monitored and very interesting catalytic performances were achieved at 550-700°C (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 Brønsted acidity probed by FTIR spectroscopy and temperature-programmed desorption of NH₃. The number of Brønsted 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.