Depolymerization of paraldehyde catalyzed by some silica- and alumina-​based binary oxide catalysts

Depolymerization of paraldehyde in C6H6 solns. is catalyzed by oxides supported on Al2O3 and SiO2. The acidity with pKa ≤-​3.0 is linearly related with catalytic activity (1st order rate const. k) for depolymerization of paraldehyde. Supported MoO3, WO3, and V2O5 have acid sites at pKa ≤-​3.0 and are catalytically active. Supported MgO, BeO, and ThO2 have very little acid strength at pKa ≤-​3.0 but have of weak acid sites at pKa ≤+3.3; these relatively weak acid sites are catalytically inactive. The obsd. rate consts. of SiO2-​supported catalysts are greater than those of the Al2O3 supported catalysts. The activation energies are inversely proportional to the acidity of the catalysts