Carbon dioxide conversion to dimethyl carbonate: The effect of silica as support for SnO2 and ZrO2 catalysts

Abundant in nature, CO2 poses few health hazards and consequently is a promising alternative to phosgene feedstock according with the principles of Green Chemistry and Engineering. The synthesis organic carbonates from CO2 instead of phosgene is highly challenging as CO2 is much less reactive. As part of our ongoing research on the investigation of catalysts for dimethyl carbonate (DMC) synthesis from methanol and CO2, we herein report results aimed at comparing the catalytic behavior of new SnO2-based catalysts with that of ZrO2. Silica-supported SnO2 and ZrO2 exhibit turnover numbers which are an order of magnitude higher than those of the unsupported oxides. Tin-based catalysts also promote methanol dehydration which makes them less selective than the zirconium analogues. Last but not least, comparison with soluble Bu2Sn(OCH3)(2) highlights the superiority of the organometallic precursor for achieving 100% selectivity to DMC but it deactivates by intermolecular rearrangement into polynuclear tin species. (C) 2010 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.