Cr/Al2O3 catalysts with strong metal-support interactions for stable catalytic dehydrogenation of propane to propylene

Chromium oxide supported on aluminum oxide (Cr/Al2O3) is one of the most widely used catalysts in propane dehydrogenation (PDH). However, a major problem of this catalyst system is fast deactivation due to the serious coke formation. Here we propose a hydrogen reduction method to adjust the strong metal-support interaction (SMSI) between Cr species and Al2O3 support. It is found that the strength of SMSI increases with the increase of H-2 pretreated temperature, and the Cr/Al2O3 catalyst with stronger metal-support interaction exhibits higher catalytic stability toward PDH. Characterizations reveal that the SMSI over Cr/Al2O3 catalysts can decrease the desorption barrier of propylene, avoiding cracking and deep dehydrogenation, and thus, increasing the catalyst stability and anti-coking ability. After 20 h time on stream, no obvious catalytic activity loss can be observed over the 700 degrees C-reduced Cr/Al2O3 catalysts, demonstrating a very promising PDH catalyst. Furthermore, the SMSI in Cr/Al2O3 system can be extended to other Cr-based catalysts such as Cr/ZrO2. This study might open a new way to design and develop highly stable Cr-based catalysts with controlled catalytic activity and selectivity.