Modification of Pd/SO4/ZrO2/Al2O3 Catalysts for n-Hexane Isomerization with HF, HNO3 and H2C2O4 Acids

Modification of Pd/SO4/ZrO2/Al2O3 catalysts with HF, HNO3 and H2C2O4 acids during the support synthesis upon mixing of aluminum and zirconium hydroxides was studied. The amount of HF and HNO3 inorganic acids was found to exert a significant effect on the textural characteristics, such as specific surface area, pore volume and effective pore diameter. In the case of oxalic acid used at the concentrations characterized by variation of acidic modulus from 0.001 to 0.1, the pore structure parameters of the catalysts remained virtually unchanged. The XRD study demonstrated that modification with HF, HNO3 and H2C2O4 acids allows controlling the ratio of tetragonal and monoclinic phases of zirconia. It was found that among the tested acids the most pronounced effect on n-hexane isomerization was exerted by the introduction of hydrofluoric acid.