Zirconia samples have been prepared from xerogels and aerogels obtained usi
ng zirconium n-propoxide as precursor. Structure and texture have been inve
stigated by X-ray diffraction, thermal analysis, transmission electron micr
oscopy, nitrogen adsorption/desorption. Surface acidity and basicity have b
een assessed by adsorption microcalorimetry, using ammonia and carbon dioxi
de as probe molecules. 4-Methylpentan-2-ol dehydration has been tested at a
tmospheric pressure in a fixed-bed flow microreactor. The xerogel gives tet
ragonal zirconia upon calcination, during which a mesoporous system is form
ed. The crystal phase depends on the presence of oxygen during the cooling
step in the case of the aerogel, whose texture is partially retained upon c
alcination. Both kinds of catalysts have well-balanced concentrations of ac
id and base sites, but the acid sites are weaker in comparison with the bas
ic ones. At 603 K the initial conversion of 4-methylpentan-2-ol over the ca
lcined xerogel and aerogel is 45 and 63%, respectively; the selectivity to
4-methylpent-1-ene is 77% for both. The occurrence of an E2-like mechanism
with the activated complex having a marked carbanionic character seems prob
able. The aerogel catalyst is quite stable during operation, whereas change
s in activity and selectivity are observed for the xerogel catalyst.