Novelties of combustion synthesized and functionalized solid superacid catalysts in selective isomerization of styrene oxide to 2-phenyl acetaldehyde

Combustion synthesis leads to very interesting characteristics to inorganic oxides which could be further modified to render them catalytic properties. Several new approaches were studied to make a novel superacidic sulfated zirconia called fuel lean sulfated zirconia (FLSZ), by combustion synthesis. FLSZ was fully characterized and used in a reaction of industrial relevance. The isomerization of styrene oxide to 2-phenyl acetaldehyde was studied by using several solid acid catalysts. 2-Phenyl acetaldehyde finds applications in the synthesis of fine chemicals, intermediates, speciality chemicals, flavors and fragrances. Among various catalysts studied FLSZ was found to give the best activity and selectivity to 2-phenyl acetaldehyde at 100 °C using cyclohexane as a solvent. Process parameters were optimized by conducting a systematic investigation. The kinetics of the reaction was also studied. The catalyst is robust, recyclable and found to be highly active and selective. The overall process is 100% atom economical, green and clean.

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► Combustion synthesis to prepare sulfated zirconia called FLSZ.
► Full characterization reveals maximum sulfur content and preservation of tetragonal phase.
► Isomerization of styrene oxide to 2-phenyl acetaldehyde at 100 °C.
► 100% conversion in 1 h with 92% selectivity to product.
► Kinetic model is proposed and validated.