Application of ZrO2-Al2O3 Aerogels to Catalysts

ZrO2-Al2O3 aerogels were prepared by hydrolysis of metal alkoxides in alcoholic solutions and supercritical drying in order to obtain an improved de-NOx catalyst with high activity in a wide temperature range. The aerogels have about 20–50% higher activity than the xerogels in the range 300–600°C. The higher activity of aerogels may be attributed to the higher effective gas diffusivity in them, estimated to be about 20–60 times higher than that of the xerogels, because of their high porosity and large pore size. The catalytic activity of aerogels containing 4–10 mol% ZrO2 is more than 20% higher than that of Al2O3 aerogels at temperatures <450°C.