Comparative study of the texture and structure of aerogel and xerogel sulphated zirconia doped with nickel

Aerogels and xerogels based on sulphated zirconia doped with nickel in the same atomic ratios S/Zr = 0.5 and Ni/Zr = 0.1 have been synthesized by sol–gel method using two drying ways of the solvent in solid preparation steps. Aerogels obtained by drying in supercritical conditions of solvent stabilize zirconia tetragonal phase even at high calcination temperatures and present a developed surface area, whereas xerogels obtained by ordinary solvent drying in an oven are amorphous. TPR and XPS studies revealed that Ni seems to exist in different species in the two kinds of solids and it is more reducible in aerogels.