焙烧温度对Cr-K2O/Al2O3催化剂异丁烷脱氢性能的影响

Effect of calcination temperature on isobutane dehydrogenation performance of Cr-K2O/Al2O3 catalysts

以活性氧化铝为载体,采用等体积浸渍法制得Cr-K2O/Al2O3催化剂前驱体,经过不同温度焙烧制得Cr-K2O/Al2O3-t催化剂。通过BET、XRD和NH3-TPD对催化剂进行表征,在固定床中考察了Cr-K/Al2O3-t催化剂催化异丁烷脱氢制异丁烯的性能。结果表明,焙烧温度影响催化剂的异丁烯收率和异丁烯的选择性,500~600℃焙烧的催化剂可获得较多活性中心,高温焙烧的催化剂表面酸性位减少,适宜的焙烧温度为600℃。在常压、500℃、异丁烷体积空速400h^-1的反应条件下,Cr-K2O/Al2O3-600催化剂上异丁烯收率和选择性分别达到50.2%和94.9%。

A series of Cr-K2O/Al2O3-t catalysts were prepared by incipient wetness impregnation method and then calcined at different temperatures. The catalysts were characterized by BET, XRD and NH3-TPD, and their catalytic performance in dehydrogenation of isobutane to isobutene was investigated in a fixed bed reactor. The results show that the calcination temperature affects the yield and selectivity of isobutene. The catalysts calcined at 500-600℃ can obtain more active sites, and the surface acid sites of the catalysts calcined at higher temperature will be reduced, indicating that the suitable calcination temperature is 600℃. Under the reaction conditions of atmospheric pressure, 500℃ and isobutane volume space velocity 400h^-1, the yield and selectivity of isobutylene over the 600℃-calcined catalyst Cr-K2O/Al2O3-600 reached 50.2% and 94.9%, respectively.