Abstract: A series of Cr catalysts supported on submicro NaZSM-5 zeolite was prepared. The obtained samples were characterized by N₂ adsorption, XRD, UV-Vis and H₂-TPR, and tested as catalysts for dehydroge-nation of propane to propylene in the presence of CO₂. The highest activity was achieved on the catalyst with a Cr content of 3% and a Si/Al molar ratio of 60. In this case, the propane conversion and propylene selectivity were 48.3%, 86.0% and 30.1%, 91.8%, respectively after the reaction at 550 ℃ for 10 min and 8 h. There is a good relationship between the initial activity and Cr⁶⁺ content of the catalysts, showing that a high content of Cr⁶⁺ species in the calcined catalyst is crucial for its high catalytic activity in dehydrogenation of propane to propylene with CO₂. A higher propylene yield was obtained during propane dehydrogentaion in the presence of CO₂ than N₂. This can be attributed to a higher surface concentration of Cr⁶⁺ retained on the catalyst in the presence of CO₂ as well as the elimination of hydrogen produced by propane dehydrogenation.

Key words: Cr/NaZSM-5, Propane, Dehydrogenation, Propylene, Carbon dioxide