• Energy Research

Abstract Ruthenium and copper nanoparticles were incorporated into MCM-41-like mesoporous silica via a fast sol-gel method at 80 °C using rice husk ash (RHA) as the silica source. The physico-chemical characterization of the synthesized materials was carried out using various analytical techniques. The X-ray diffraction results indicated that the mesoporous silica synthesized in this study had the standard MCM-41 structure. The Fourier transform infrared spectroscopy results showed that ruthenium and copper ions were successfully incorporated into the hexagonal framework of the mesoporous materials. The transmission electron microscopy results revealed that the RHA-MCM-41, MCM-41-10Ru, and MCM-41-10Ru10Cu samples consisted of ordered mesoporous straight channels. MCM-41-10Cu consisted of copper nanospheres. MCM-41-10Ru and MCM-41-10Ru10Cu showed ruthenium nanoparticle agglomerates distributed on their external MCM-41 framework surfaces. In the case of MCM-41-10Cu and MCM-41-10Ru10Cu, copper ions were homogeneously dispersed on the internal surface of the agglomerated porous silica matrix. The as-prepared Ru- and Cu-doped MCM-41 catalyst was used for the acetylation of glycerol. The catalyst showed a high conversion of 98% and high shape selectivity towards the formation of diacetin and triacetin unlike conventional silica-based catalysts, which show selectivity towards the formation of monoacetin.

The storage, utilization, and control of the greenhouse (CO2) gas is a topic of interest for researchers in academia and society. The present review article is dedicating to cover the overall role of ionic liquid-modified hybrid materials in cycloaddition reactions. Special emphasis is on the synthesis of various cyclic carbonate using ionic liquid-based modified catalysts. Catalytic activity studies have discussed with respect to process conditions and their effects on conversion and product selectivity for the reaction of cycloaddition of CO2 with styrene oxide. The reaction temperature and the partial pressure of CO2 have found to play a key role in cyclic carbonate formation. The role of other influential parameter (solvent effect) is also discussed for the conversion of cyclic/aromatic oxides to polycarbonate production. Our own research work that deals with ionic liquid-based halide-modified mesoporous catalyst (MCM-41 type) derived from rice husk waste has also been discussed. Finally, the role of carbon dioxide activation and ring-opening mechanisms involved in the cyclic carbonate product formation from CO2 have been discussed.