Enhanced catalytic performance with adjustable morphology and surface properties of alumina for propane dehydrogenation: Promote the catalytically active chromium sites, dispersion and anti-coking

To examine the effect of the morphology of alumina on the catalytic performance during non-oxidative dehydrogenation of propane, a series of Al2O3 supports with specific morphologies including sheet-like, rod, and nucleoshell were synthesized using a template-free hydrothermal route at different temperatures. The activity results show that catalysts with special morphology have better catalytic performance than the conventional alumina-based catalysts. Cr-AlNC catalyst with nucleoshell morphology cause a significant growth of Cr6+ species compared to other catalysts. The reduction of this species results in the creation of the most reactive Cr sites that are coordinatively unsaturated in the PDH reaction. This reduction also prevents the transformation of Cr species into α-Cr2O3. Cr-AlNC catalyst show anti-coking ability and great resistance against deactivation due to their unique morphology and more importantly, the strong metal-support interaction in addition to the low deactivation rate and coke deposition of 0.1 h−1 and 1.5%, respectively. However, the corresponding values for the reference catalyst are 0.44 h−1 and 6.1%, respectively.