The direct synthesis of dimethyl carbonate out of carbon dioxide and methanol is catalyzed by D-metals supported on various matrices

Abstract

The chemical transformation of carbon dioxide (CO2) into valuable chemicals is a fascinating way to reduce CO2 concentration in the atmosphere. Dimethyl carbonate (DMC) exhibits low toxicity, biodegradability, and versatile reactivity. DMC production by direct synthesis using CO2 and methanol (CH3OH) may be one of the ever most promising green routes. On the other hand, direct synthesis of DMC shows some drawbacks including unfavorable thermochemistry and quick deactivation of catalysts. The development of new catalytic systems currently represents an urgent agenda to overcome these disadvantages. This study investigates the catalytic activity of iron (Fe) and copper (Cu) catalysts supported on alumina (AL), silica (SI), and eggshells (ES) during the course of DMC production by direct synthesis. The supported catalysts were synthesized using the impregnation method and characterized by TGA, BET, DTP-NH3, XRD, and FESEM/EDS. The contents of the impregnated iron in the matrices are ES-Fe (13%) > AL-Fe (6%) > SI-Fe (4%). The contents of the impregnated copper are ES-Cu (7%) > AL-Cu (3%) = SI-Cu (3%). The DMC conversions equal 8.9 (AL-Cu), 6.2 (SI-Cu), 11.3% (ES-Cu), 6.1 (AL-Fe), 7.2 (SI-Fe), and 12.7% (ES-Fe). The ES-Fe recycle demonstrated stability of the catalytic action in the first and second reuse, maintaining high conversion and selectivity of DMC. All tests reveal a DMC selectivity of over 99%. The reported results suggest that the catalytic DMC production depends both on the nature of d-metal and support, whereas the ES-Fe system exhibits the best performance.