Combustion Synthesis of Amorphous Al and Cr Composite as the Catalyst for Dehydrofluorination of 1,1-Difluoroethane

Interaction or lattice doping between Cr and Al contributes to the acidity and catalytic activity of Cr/Al catalysts, which is difficult to be achieved by the conventional preparation methods while maintaining nanostructures. We suggest that solution combustion synthesis (SCS) is one of the effective ways for this issue. Nanoscale Cr/Al composite catalysts of sheet structure with a thickness around 40-100 nm were fabricated via simple solution combustion method with Cr(NO3)(3)center dot 9H(2)O and Al(NO3)(3)center dot 9H(2)O as the precursors and glycine as the fuel. Following SCS and fluorination pretreatment, Cr species interact with Al species intimately forming an amorphous structure. The interaction provides relatively high amounts of defects and is favorable for the formation of active species, resulting in the enhanced Lewis acidity and catalytic activity. At 400 degrees C, a reaction rate of 33.9 mmol/h/g was achieved for the dehydrofluorination of HFC-152a over composite catalyst, which is 30-40% higher than that of Cr and Al catalysts.