Nanosized sulfated zinc ferrite as catalyst for the synthesis of nopol and other fine chemicals

A nanosized highly ordered mesoporous zinc ferrite (ZnFe2O4; ZF) was synthesized via co-precipitation method, further sulfated with ammonium sulfate solution to obtain sulfated ZF (SZF) and have been used for the synthesis of nopol by Prins condensation of β-pinene and paraformaldehyde. The NH3-TPD and pyridine sorption DRIFT-IR studies revealed the significant enhancement in Lewis acidic sites of the zinc ferrite on sulfatation. The influence of various reaction parameters such as reaction temperature, effect of substrate stoichiometry and catalyst loading has been investigated. It gave 70% conversion of β-pinene with 88% selectivity to nopol. The spent catalyst was regenerated and reused successfully up to four cycles with slight loss in catalytic activity. The nanosized SZF catalyst was found to be highly active towards several other commercially important acid catalyzed reactions such as isomerization, acetalization and aldol condensation.

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► ZnFe2O4 catalyst was synthesized by co-precipitation method.
► Lewis acidity of ZnFe2O4 was observed to increase on sulfatation.
► 70% β-pinene conversion with 88% selectivity to nopol achieved.
► Aldol condensation, isomerization and acetalization reactions were investigated.