Solution Combustion Synthesis of Cr₂O₃ Nanoparticles and the Catalytic Performance for Dehydrofluorination of 1,1,1,3,3-Pentafluoropropane to 1,3,3,3-Tetrafluoropropene

Cr₂O₃ nanoparticles were prepared by solution combustion synthesis (SCS) with chromium nitrate as the precursor and glycine as the fuel. Commercial Cr₂O₃ and Cr₂O₃ prepared by a precipitation method were also included for comparison. The morphology, structure, acidity and particle size of fresh and spent Cr₂O₃ catalysts were investigated by techniques such as XRD, SEM, TEM, BET and NH₃-TPD. In addition, catalytic performance was evaluated for the dehydrofluorination of 1,1,1,3,3-pentafluoropropane (CF₃CH₂CHF₂, HFC-245fa) to 1,3,3,3-tetra-fluoropropene (CF₃CH=CHF, HFO-1234ze). The catalytic reaction rate of Cr₂O₃ prepared by SCS method is as high as 6 mmol/h/g, which is about 1.5 times and 2 times higher than that of precipitated Cr₂O₃ and commercial Cr₂O₃, respectively. The selectivity to HFO-1234ze for all the catalysts maintains at about 80%. Compared with commercial and precipitated Cr₂O₃, Cr₂O₃-SCS prepared by SCS possesses higher specific surface area and acid amount. Furthermore, significant change in the crystal size of Cr₂O₃ prepared by SCS after reaction was not detected, indicating high resistance to sintering.