Conversion of Carbon Dioxide into Formaldehyde

As carbon dioxide (CO2) is an undesirable greenhouse gas inducing global warming, CO2 transformation to value-added chemicals emerges as one of the ideal approaches for environmental remediation and greenhouse gas mitigation. Formaldehyde is an essential base chemical in petrochemical industry and important building chain for the production of useful life commodities. Currently, formaldehyde is industrially produced from methane via multiple energy-intensive processes including reforming, methanol synthesis, and methanol partial oxidation. Thus, the direct conversion of CO2 to this important chemical has been extensively focused and explored in industrial production and academics. This chapter provides a comprehensive and recent review about the current catalytic approaches for converting unwanted CO2 greenhouse gas to formaldehyde. Particularly, photocatalytic CO2 reduction to formaldehyde was systematically reviewed in terms of thermodynamics, mechanism, catalyst design, and catalytic performance. Apart from photocatalytic method, CO2 hydrogenation, selective methane oxidation, and homogeneous CO2 reduction were also discussed thoroughly in this chapter.