Decomposition of styrene dimers on Al2O3–Cr and Al2O3–SiO2–Cr catalysts of acid and redox nature

摘要: The transformations of styrene dimers at 753 K over catalysts possessing Lewis acid centers as well weak Bronsted sites HO > −2.2 (γ-Al2O3); acid, −3.5 < ≤ and redox (γ-Al2O3–Cr); strong −14 (SiO2–Al2O3(13 %)), 14 %)–Cr) have been studied. It was established that the following surface groups are responsible for catalytic activity in transformation dimers. γ-Al2O3: OH group adjacent to Al3+ cation (alkenyl chain protonation) (allylic anion generation); γ-Al2O3–Cr: originating from chromium ions high oxidation states Cr3+ SiO2–Al2O3(13 %)–Cr: silica–alumina aromatic ring generation). protonation dimer alkenyl leads β-cleavage toluene α-methylstyrene ethylbenzene. allylic species formed react different isomers through diphenylbutadiene intermediate coke. use methylcyclohexane solvent presence containing results aromatization reaction leading hydrogen. later reactant system causes hydrogenation ethylbenzene cumene.