Synthesis and Application of Encapsulating Metal/Sulfonic Dual-Acid Based Phosphotungstic Acid Ionic Liquids

Graphical In this study, we present a novel metal/sulfonic dual-acid based phosphotungstic acid ionic liquid catalyst for the ketone reaction of cyclohexanone with ethylene glycol. The ionic liquid was embedded into a B-SBA-16 carrier, and exhibited excellent catalytic properties and cycling stability. The conversion of cyclohexanone was 94.05 %, and the yield of ketal was 83.45 %. In recent years, ionic liquids have been widely used for industrial acid-catalysis. The enhancements of the acidity and immobilization of ionic liquids have been drawing increasing attention from researchers. In this study, dual-acid based phosphotungstic acid ionic liquids (PWILs) modified by a variety of metal ions (Fe 3+ , Cu 2+ , Al 3+ ) and sulfonic acid group (−SO 3 ) were synthesized. They were subsequently embeded into B-SBA-16 mesoporous molecular sieves with acidic sites to produce a plurality of encapsulating metal/sulfonic dual-acid based phosphotungstic acid ionic liquids (M n PWIL/B-SBA-16s) composite catalysts. The structural properties, thermal stability, and encapsulation of the as-fabricated composite catalysts were systematically investigated by FT-IR, BET, SAXD, TEM, TG-DSC and XPS. Moreover, the catalytic performances of the composite catalysts were evaluated using the ketalization of cyclohexanone with ethylene glycol as a model reaction. Among the different composite catalysts, Al 0.50 PWIL/B-SBA-16 showed the highest cyclohexanone conversion of 94.05 % and the maximum cyclohexanone glycol ketal yield of 83.45 %. Meanwhile, this catalyst still exhibited superior catalytic properties after five cycles of the catalytic reaction. These results demonstrate the high activity and durability of the novel ionic liquid composite catalyst.