Abstract: The influence of different Mg content of Cr2O3/Al2O3 catalysts for propane dehydrogenation reaction was investigated. The catalysts were characterized by N2 adsorption at low temperature，XRF，XRD，NH3-TPD，H2-TPR and SEM , to discuss the influence of different Mg content of Cr2O3/Al2O3 catalysts to catalyst physical structure, acidity, crystal type and valence state. Results showed that the major reason for MgO improves the reaction of propylene selectivity is that reducing the carrier surface acid amount, adjusting the valence distribution of Cr in the catalyst, and making the Cr better dispersion on the carrier. If the Cr2O3 content is 18% in the Cr2O3-MgO /Al2O3 catalyst, the appropriate addition of MgO is 1%—2% that catalyst had the best catalytic performance. Under the reaction condition, the propane average conversion of 33% was achieved with the corresponding propylene average selectivity of higher than 93% during reaction for 3 h.

Key words: propane dehydrogenation, chrome oxide, magnesia