Cr/NaZSM-5催化剂上CO2氧化丙烷脱氢反应

以亚微米级NaZSM-5为载体合成了一系列负载型Cr催化剂, 采用氮气吸附、 XRD、 UV-Vis和H2-TPR对Cr/NaZSM-5催化剂的结构和织构性质进行了表征, 并评价了催化剂在CO2气氛下的丙烷脱氢性能. 硅铝摩尔比为60, Cr质量分数为3%的催化剂具有最高的反应活性, 于550 ℃反应10 min和8 h后的丙烷转化率分别为48.3%和30.1%, 丙烯选择性则分别为86.0%和91.8%. 催化剂中的Cr6+含量和反应初活性具有良好的对应关系, 表明高Cr6+含量对催化剂表现出高的丙烷脱氢活性是至关重要的. CO2气氛下的丙烯产率明显比氮气气氛下的高, 这是由于CO2气氛下催化剂表面有较多量的Cr6+, 并且CO2可通过逆水煤气变换反应除去脱氢反应生成的氢.

Oxidative Dehydrogenation of Propane to Propylene with CO2 over Cr/NaZSM-5 Catalysts

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.