Synthesis of acid functionalized mesoporous ZrOSO2CF3 catalysts; heterogenization of CF3SO3H over mesoporous Zr(OH)4 Original Research Article

Mesoporous Zr(OH)4 was synthesized using N-cetyl-N,N,N-trimethyl ammonium bromide (CTMABr) as surfactant at atmospheric pressure and reflux conditions for 48 h. After removal of the surfactant, the resulting mesoporous solid was functionalized with triflic acid (CF3SO3H, trifluoromethanesulfonic acid) in order to get the functionalized mesoporous ZrOSO2CF3 (ZrOSO2CF3 (M)) with enhanced acidity. The mesoporous Zr(OH)4 and ZrOSO2CF3 (M) catalysts were characterized by X-ray diffraction, N2 adsorption–desorption, FT-IR and solid-state NMR spectroscopy. The strength of acid sites in Zr(OH)4 and ZrOSO2CF3 (M) samples was evaluated by temperature programmed desorption (TPD) of ammonia using various steps of NH3 desorption (303–573 K). As the mesoporous Zr(OH)4 is functionalized with triflic acid, the surface area, pore volume and pore diameter of the functionalized catalyst decreased, whereas the acidity increased. A significant activity of the ZrOSO2CF3 (M) catalyst is observed in the benzoylation of biphenyl (BP) because of the enhanced acidity and mesoporosity. Amorphous Zr(OH)4 was also functionalized with triflic acid for comparison. The catalytic activity of functionalized mesoporous ZrOSO2CF3 was found to be 13 times higher than that of mesoporous Zr(OH)4, two times higher than that of functionalized amorphous ZrOSO2CF3 and six times higher than that of SO42−/ZrO2.