Epoxides to cyclic carbonates conversion utilizing CO2 is one of the efficient approaches for CO2 fixation. Atmospheric fixation of CO2 generally required the use of halogen containing catalysts or additionally...
In this work we have achieved epoxide to cyclic carbonate conversion using a metal-free polymeric catalyst under ambient CO 2 pressure (1.02 atm) using a balloon setup. The triazine containing polymer (CYA-ANIS) was prepared from cyanuric chloride (CYAÀ Cl) and o-dianisidine (ANIS) in anhydrous DMF as solvent by refluxing under the N 2 gas environment. The presence of triazine and amine functional groups in the polymer results in the adsorption of CO 2 up to 7 cc/g at 273 K. This inspired us to utilize the polymer for the conversion of a series of functionalised epoxides into their corresponding cyclic carbonates in the presence of tetrabutyl ammonium iodide (TBAI) as cocatalyst. The product has wide range of applications like solvent in lithium ion battery, precursor for polycarbonate, etc. The catalyst was efficient for the conversion of different mono and di-epoxides into their corresponding cyclic carbonates under atmospheric pressure in the presence of TBAI as co-catalyst. The study indicates that epoxide attached with electron withdrawing groups (like, CH 2 Cl, glycidyl ether, etc.) displayed better conversion compared to simple alkane chain attached epoxides. This is mainly due to the stabilization of electron rich intermediates produced during the reaction (e. g. epoxide ring opening or CO 2 incorporation into the halo-alkoxide anion). This catalyst mixture was capable to maintain its reactivity up to five cycles without losing its activity. Post catalytic characterization clearly supports the heterogeneous and recyclable nature of the catalyst.[a] Dr.
The quest toward sustainability and decarbonization demands
the
development of methods for efficient carbon dioxide capture and utilization.
The nonreductive CO2 fixation into epoxides to prepare
cyclic carbonates has gained attention in recent years. In this work,
we report the development of guanidine hydrochloride-functionalized
γ alumina (γ-Al2O3), prepared using
green solvents, as an efficient bifunctional catalyst for CO2 fixation. The resulting guanidine-grafted γ-Al2O3 (Al–Gh) proved to be an excellent catalyst to
prepare cyclic carbonates from epoxides and CO2 with high
selectivity. The nitrogen-rich Al–Gh shows increased CO2 adsorption capacity compared to that of γ-Al2O3. The as-prepared catalyst was able to carry out CO2 fixation at 85 °C under atmospheric pressure in the
absence of solvents and external additives (e.g., TBAI or KI). The
material showed negligible loss of catalytic activity even after five
cycles of catalysis. The catalyst successfully converted many epoxides
into their respective cyclic carbonates under the optimized conditions.
The gram-scale synthesis of commercially important styrene carbonates
from styrene oxide and CO2 using Al–Gh was also
achieved. Density functional theory (DFT) calculations revealed the
role of alumina in activating the epoxide. This activation facilitated
the chloride ion to open the ring to react with CO2. The
DFT studies also validated the role of alumina in stabilizing the
electron-rich intermediates during the course of the reaction.
In this work a series of chitosan‐based catalysts with ranging hydrophobic/hydrophilic balance are successfully prepared by varying the ionic liquid and hydrocarbon chain length attached to chitosan. The chitosan modified with eight carbon units displayed efficient catalytic activity for the conversion of a wide range of epoxides to their corresponding cyclic carbonates under 1 atmosphere pressure of carbon dioxide without cocatalyst and solvent. The optimized catalyst was able to convert even diepoxides and sterically bulky epoxides like t‐butyl glycidyl ether to their corresponding cyclic carbonates. This study provides an insight into catalyst designing based on possible molecular interaction between reactants and active sites of the catalyst.
Utilization of carbon dioxide by converting it into value-added chemicals is a sustainable remedy approach which stipulates abundant, cheap, non-toxic and efficient catalytic materials. In this study, we have demonstrated...
Two new 2D microporous MOFs based on bent carboxylates and an unexplored N,N-donor spacer containing imine and amide functionalities exhibited high IAST selectivity for CO2/N2 and CO2/CH4 mixtures under ambient conditions.
The rising global warming and associated climate change demand efficient tactics to reduce CO2 concentration in the atmosphere. Conversion of epoxides to cyclic carbonates utilizing CO2 is a promising and sustainable approach towards CO2 fixation. However, the inert nature of CO2 and high activation energy requirement for the particular reaction necessitate the use of efficient catalysts. In this work, we have designed and developed a heterogeneous catalyst using catechol functionalized guanidinium based ligands (L1) and Fe(III) ions to perform the CO2 fixation reaction. The resulting amorphous material (Fe−L1) possesses metal‐organic network as revealed through different characterization methods. The optimized catalyst Fe−L1 is efficient for the conversion of a variety of epoxides into their corresponding cyclic carbonates in very good yield (>80 %). The reactions were performed under atmospheric pressure without solvent and external additives (e. g., TBAI or KI). The investigation of the mechanistic pathway indeed validates the synergistic effect of metal and halide ions that leads to the efficient conversion of different epoxides into cyclic carbonates. Furthermore, no significant loss in the catalytic activity of the Fe−L1 is noticed up to six cycles. The post catalytic analyses clearly indicate the robust nature of the catalyst. The developed one component bifunctional catalytic system can pave way towards transition to sustainable carbon capture and conversion.
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