Ruthenium-Based Macromolecules as Potential Catalysts in Homogeneous and Heterogeneous Phases for the Utilization of Carbon Dioxide

Ruthenium-containing tetraphenylporphyrin (Ru-TPP) molecule was prepared, and the structural elucidation was confirmed using 1H nuclear magnetic resonance (NMR), CHN, and mass spectral analyses. The incorporation of ruthenium ion into the cavities of the macromolecule was confirmed from the disappearance of the 1H NMR signal, characteristic of the N-H bond (-2.72 ppm in TPP). The CHN and mass spectral analyses of the ligand and metallomacromolecules are consistent with the theoretically calculated values. The homogeneous Ru-TPP macromolecule is grafted on the surface of aminosilane-, diaminosilane-, and iodosilane-functionalized SBA-15 molecular sieves. The successful grafting of Ru-TPP on functionalized mesoporous molecular sieve materials was evident from low-angle powder X-ray diffraction, 13C magic angle spinning NMR, and scanning electron microscopy-energy-dispersive X-ray analyses. The resultant homogeneous and heterogenized Ru-TPP catalysts were used for the utilization of carbon dioxide (CO2) under moderate reaction conditions. The homogeneous Ru-TPP catalyst showed first-order kinetics with respect to epoxide with the exclusive formation of cyclic carbonate (about 98%) and an activation energy of 16.07 kg/mol, which is much lower than some of the reported catalysts. Ru-TPP grafted on aminosilane- and iodosilane-functionalized materials showed better catalytic activity (above 90% conversion and 83-96% cyclic carbonate selectivity) and reusability for the chosen reaction.

Mechanistic insights into CO2 cycloaddition of styrene oxide on paddle-wheel metal clusters: a theoretical study

The reaction mechanisms for the CO₂ cycloaddition of styrene oxide catalyzed by M–BTC clusters have been systematically elucidated by means of the M06-L functional.

Carbon dioxide adsorption and cycloaddition reaction of epoxides using chitosan-graphene oxide nanocomposite as a catalyst

One of today's major challenges is to provide green materials for a cleaner environment. We have conducted studies on carbon dioxide (CO₂) adsorption and conversion to valuable products by an ecofriendly approach based in chitosan/graphene oxide (CSGO) nanocomposite film. Rheological behavior indicates that the CSGO has a better solvation property than the pure chitosan. An adsorption capacity of 1.0152mmolCO₂/g of CSGO nanocomposite at 4.6bar was observed. The catalytic behavior of the CSGO nanocomposite in the presence of tetra-n-butylammonium iodide (n-Bu₄NI) as co-catalyst was evaluated for the cycloaddition of CO₂ to epoxides, to give cyclic carbonates, in the absence of any solvent. These results strongly suggest that the CSGO nanocomposite may open new vistas towards the development of ecofriendly material for catalytic conversion and adsorption of CO₂ on industrial scale.

A chiral salen-based MOF catalytic material with high thermal, aqueous and chemical stabilities

A highly stable chiral Ni(salen)-based MOF material possessing a 1D open channel can efficiently catalyze the cycloaddition of simulated industrial CO₂ with epoxides, as well as the cycloaddition of epoxides with azides and alkynes under mild conditions.

Two dimensional covalent organic framework materials for chemical fixation of carbon dioxide: excellent repeatability and high selectivity

Two dimensional (2D) metalloporphyrin-based covalent organic framework (COF) composites were synthesized and employed to catalyze the coupling of CO₂ and epoxides to form cyclic carbonates.

Design, synthesis and characterization of novel dioxime ligand-based cobaloxime compounds for application in the coupling of CO2 with epoxides

Novel dioxime-based cobaloxime complexes have been obtained by click chemistry and used as catalysts for the conversion of CO₂ to a cyclic carbonate without using any solvent.