Abstract
The different type of halide modified mesoporous silica catalysts were prepared via post-grafting technique using meso-silica derived from rich husk by simple sol-gel method. The physico chemical characterizations of as prepared catalysts were characterized using FT-IR, N2-sorption-desorption study, 13C CP/MAS NMR and SEM techniques. FT-IR and 13C CP/MAS NMR revealed the effective anchorage of imidazole and 1,2-dihaloethane on the MCM-41. SEM analysis images shows the comprise worm-like agglomerated structure which was similar to MCM-41. The catalysts were then used in cycloaddition of carbon dioxide and phenyl glycidyl ether under solvent free or less conditions. Among the prepared catalyst, Br-immobilized MCM-41 shows higher catalytic activity (96.7%) under ambient reaction by adopting following conditions such as 100 °C, 20 bar initial CO2 pressure, 300 mg catalyst mass and 3 h. The conversion of phenyl glycidyl ether using ImI-MCM-41 and ImCl-MCM-41 are 77.3% and 26.4% respectively. The catalytic results are confirmed that the synergistic effect owing to the stronger nucleophilicity of bromide− and amine could be promoted the reaction smoothly. The catalyst was recovered and reused for four times without a significant decrease in activity or product selectivity. A possible site for CO2 activation by ImBr-MCM-41 catalyst could be the potential ionic liquid mimic's halide immobilized MCM-41 like material for efficient conversion of the substrates such as phenyl glycidyl ether and Epoxy hexane for cycloaddition reactions have been demonstrated.
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•Halide modified MCM-41 was synthesized successfully by sol-gel formation followed by halide immobilization process.•ImBr-MCM-41 modified ionic liquid type catalyst shows higher catalytic activity due to the synergistic effect.•Solvent free method developed for phenyl glycidyl carbonates (PGC) formation.