Acidity of sulfated oxides: Al₂O₃, TiO₂and SiO₂. Application of test reactions

Decomposition of styrene dimers: the influence of the acid strength of the catalyst

“…The acidity of c-Al 2 O 3 /SO 4 2-catalytic system depends on the surface concentration of H 2 SO 4 [19]. This can be seen from the results of the test reactions (Fig.…”

“…Sulfated alumina is a solid acid of high acid strength [16], which can even pass superacid limits [17,18]. In our previous work [19], we showed that the acid strength of the c-Al 2 O 3 /SO 4 2-system strongly depends on the concentration of sulfuric acid. Acid strength was measured using the test reaction method.…”

Styrene and styrene dimer derivatives, cyclohexene, tert-butylbenzene and cumene as test reactions for acid strength measurements of crystalline and amorphous silica-aluminas, sulfated oxides and Amberlyst

“…Thus, the acid strength of sulfated alumina with H 2 SO 4 content equal to 8 % attains the level of -11. The results of acid strength measurements for sulfated oxides studied are gathered in the On the basis of our results, both sulfated oxides cannot be classified as superacids though they catalyze pentane isomerization at ambient temperature [41]. However, they possess strong protic sites (-11.5 \ H O B -10.8).…”

“…The reported reaction conditions (Table 1) indicate that acid solutions of low acid strength (H O = -2.2) at elevated temperature can catalyze only a-methylstyrene dimerization. The same reaction for styrene is reported on alumina and titania [41]. All organic reactants, sulfuric, trifluoromethanesulfuric and trifluoroacetic acids were supplied by Aldrich.…”

“…All the studied catalysts were able to initiate diphenylmethane transformation and were classified as superacids. In our previous works [41][42][43][44], the acid properties of sulfated titania and alumina as well as sodium and chromium doped silica-aluminas and alumina were studied. A (1) and low (2) proton affinity semiquantitative test reaction method was applied since the minimal acid strength required for the reactions to proceed was not measured, but taken from the literature.…”