Fluorinated Zirconia Prepared by Anionic Exchange of Zirconium Oxo/Hydroxide with Trifluoroacetic Acid: Structure, Acid‐Base and Catalytic Properties

Abstract

AbstractFluorinated zirconia were prepared by anionic exchange between commercial zirconium oxo/hydroxide of high surface area and trifluoracetic acid solutions. The new fluoride‐based catalysts contained high amount of F with superficial Zr/F ratio of 0.9 and 1.2 after calcination at 300 °C and 400 °C, respectively, and retained high surface areas. The impact of F insertion on the catalyst's acid‐base properties was studied by calorimetry of NH3 and CO2 adsorption and FTIR of pyridine adsorption. The insertion of F species was shown to inhibit the basicity of zirconia and to generate Brønsted acidity ascribed to the electron withdrawing of Fluorine. This is consistent with the selectivity changes observed in the gas phase isopropanol conversion leading to formation of propene at the expense of acetone over zirconia and selective aqueous phase dihydroxyacetone conversion into pyruvaldehyde with reduced formation of hexoses and Lactic acid upon F loading within zirconia framework. Fluorine atoms also made the catalyst's surface more hydrophobic.