Heterogeneous Catalysis for Chemical Fixation of CO₂ via Carbonylation Reactions

One of the major constituents of greenhouse gases is carbon dioxide whose concentration in the atmosphere is increasing at an alarming rate due to the disorganized human activities. Therefore, capturing CO₂ and utilizing it to make various value-added chemicals is regarded as a green transformation, which thereby balances the carbon footprint. In this chapter, the advances in CO₂ as the C₁ source by utilizing it as a carbonylating agent for important organic transformations for the synthesis of cyclic carbonate, substituted urea, cyclic urea, carbamates, glycerol carbonate and dimethyl carbonate are discussed. These products have a wide range of applications as specialty solvents, starting materials/intermediates for polymer, paint, agrochemicals, pesticides, herbicides and pharmaceutical industries. Also, a few products like dimethyl carbonate have potential applications as fuel additives. Although CO₂ is thermodynamically and kinetically stable molecule, it can be activated by basic sites in the catalyst due to the electron deficiency of the carbonyl carbon at appropriate reaction condition. Various catalyst systems such as metal oxides, mixed metal oxides, supported metal oxides, metal-organic framework, bifunctional catalysts and importance of solvent have been highlighted and discussed in detail for the efficient production of these commercially important chemicals from CO₂.