TITANIA ZIRCONIA MIXED-OXIDE AEROGELS AS SUPPORTS FOR HYDROTREATING CATALYSTS

Supercritical fluid (SFC) extraction was used to make aerogels of TiO2, ZrO2 and two TiO2/ZrO2 mixed oxides, having surface areas from two to five times greater than their conventionally prepared equivalents; additionallY the mixed oxides have higher surface acidities than the two single component oxides. Heat treatments, either during catalyst preparation or reactor testing, always resulted in small to significant decreases in surface areas in the aerogel-containing samples. These samples were used as supports for Mo-Ni catalysts for the hydroprocessing of gas oil in a pilot-plant scale reactor. The high ZrO2 Containing materials were found to be unstable under reaction conditions and were nearly inactive; in contrast, the high TiO2 containing catalysts, while somewhat unstable, are more active on a surface area basis than Al2O3 or conventional TiO2 equivalent supported Mo-Ni catalysts. This improvement is attributed to properties inherent in the SCF prepared supports; these results also indicate that support acidity contributes to hydrotreating activity.