Formation of Value-Added Cyclic Carbonates by Coupling of Epoxides and CO₂by Ruthenium Pincer Hydrazone Complexes under Atmospheric Pressure

Abstract

Transforming atmospheric CO2 into industrially valuable cyclic carbonates is of great importance and one of the attractive approaches for reducing CO2 concentration in the biosphere. However, the selectivity and conversion of ruthenium catalysts for cyclic carbonate formation via CO2 insertion to epoxides are low at high pressure. Here, a series of novel ruthenium complexes supported by ONN pincer-type hydrazone ligands were successfully generated, and their potential for CO2 valorization to cyclic carbonates was investigated. NMR, Fourier transform infrared (FT-IR), mass spectrometry, elemental analysis, and single-crystal diffraction analysis further confirmed the structures of these ruthenium compounds. These compounds were utilized for the CO2/coupling reaction after thorough characterization. Fortunately, these complexes outperform the reported ruthenium catalysts with a turn-over frequency of 833 h–1 and >99% selectivity at atmospheric pressure without any assisted cocatalyst. The designed catalyst showed consistent catalytic performance over five repeating cycles.

Environmentally Sustainable Large-Scale CO2 Sequestration through Hydrates in Offshore Basins: Ab Initio Comprehensive Analysis of Subsea Parameters and Economic Perspective

“…Carbon sequestration methodologies such as biotic carbon sequestration and abiotic/geological carbon sequestration methods have been studied in the recent past. − Carbon sequestration through biomass-producing plants in wetlands, terrestrial, biota and aquatic regions are some of the biotic carbon sequestration methods. Moreover, biotic carbon sequestration routes are not just cost-efficacious and sustainable but also produce value-integrated products such as biodiesel, bio-oils, bioethanol, biomethanol, and dimethyl ether. ,− In recent years, scientists have converted CO 2 into antioxidants, biochemicals and biofertilizers through different metabolic pathways in the presence of different heterotrophic and autotrophic microorganisms. − Even though soil and microbial carbon sequestration are highly effective, the rate of CO 2 fixation is low, and it requires a lot of soil and the entire life cycle to fix CO 2 . Abiotic or geological carbon sequestration methods are also utilized for carbon sequestration in depleted oil and natural gas reservoirs.…”

Nickel Supported on Mesoporous Organosilica Nanoparticles Incorporating Pyridine-Based SNS Ligand as an Efficient Recoverable Catalyst for Chemical Fixation of CO2

“…To design a metal catalytic system with high activity and selectivity for the synthesis of five-membered cyclic carbonate, the nature of ligands generally plays important roles through the tuning of electronic properties of the metal species . Along this line, the pincer ligands have emerged as a powerful candidate for metal-catalyzed CO 2 cycloaddition to epoxide. − It is well-documented that the strong binding of metal centers to tridentate coordination of a pincer ligand led to the high stability of metal centers in a pincer, properties that make them a robust catalyst candidate that can be operable at higher temperatures. , Moreover, it is possible to coordinate in well-defined ways with pincers as well as labile ligands can be firmly bound . Ideally, a metal-catalyzed CO 2 fixation requires thermally stable complexes, which a pincer can provide.…”