Carbon dioxide (CO2) utilization is an important area of research to potentially reduce CO2 concentrations in the environment.  The simplest chemical transformation of CO2 into a liquid product is the hydrogenation to formic acid.  Homogeneous (soluble) iridium catalysts have been employed to produce formic acid with relatively high turnover numbers.  However, catalyst separation is often difficult with soluble catalysts and leads to energy intensive separations to recover the catalysts.  As a means to minimize these costs, we report single-site inspired silica-tethered Ir catalysts that are active for the hydrogenation of CO2 to formic acid.  The synthesis of these well-defined ?2-iminophosphine iridium catalysts tethered to both silica and polyethyleneimine supports is discussed.  These materials have been characterized by FT-IR, ICP-OES, TGA, FT-Raman, UV-Vis, N2 physisorption, and XPS.  Our catalytic results indicate that tethered bidentate catalysts are more active than tethered monodentate phosphine-Ir catalysts.

Silica and polymer tethered iridium catalysts for the reduction of CO<sub>2</sub> to formic acid

245th National Meeting (2013)

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Silica and polymer tethered iridium catalysts for the reduction of CO2 to formic acid

Silica and polymer tethered iridium catalysts for the reduction of CO₂ to formic acid