Carbon Dioxide to Methanol: The Aqueous Catalytic Way at Room Temperature

Abstract

Carbon dioxide may constitute a source of chemicals and fuels if efficient and renewable processes are developed that directly utilize it as feedstock. Two of its reduction products are formic acid and methanol, which have also been proposed as liquid organic chemical carriers in sustainable hydrogen storage. Here we report that both the hydrogenation of carbon dioxide to formic acid and the disproportionation of formic acid into methanol can be realized at ambient temperature and in aqueous, acidic solution, with an iridium catalyst. The formic acid yield is maximized in water without additives, while acidification results in complete (98 %) and selective (96 %) formic acid disproportionation into methanol. These promising features in combination with the low reaction temperatures and the absence of organic solvents and additives are relevant for a sustainable hydrogen/methanol economy.

Catalytic Disproportionation of Formic Acid to Methanol by an Iridium Complex Immobilized on Bipyridine‐Periodic Mesoporous Organosilica

“…[2,11] This is reasonable because the H 2 / CO 2 pressure suppresses the excess FA dehydrogenation (Scheme 2) and promotes the FA hydrogenation to produce MeOH (Scheme 3). [2,11] This is reasonable because the H 2 / CO 2 pressure suppresses the excess FA dehydrogenation (Scheme 2) and promotes the FA hydrogenation to produce MeOH (Scheme 3).…”

“…[2] However, there were problems in improving the catalysis for hydrogenation of CO 2 to FA and subsequent hydrogenation of FA to MeOH. [2] However, there were problems in improving the catalysis for hydrogenation of CO 2 to FA and subsequent hydrogenation of FA to MeOH.…”

“…[11] Cantat et al reported the highly selective MeOH generation using ruthenium catalysts and methanesulfonic acid as an acid additive in a closed system at 150°C (selectivity: 50.2 %). [2,11] Since reaction system under atmospheric pressure (open system) would be more desirable for easy handling, a new approach is needed to improve MeOH selectivity of the disproportionation of FA under atmospheric pressure. It is known that the disproportionation of FA is composed of dehydrogenation of FA (Scheme 2) and hydrogenation of FA by produced H 2 (Scheme 3).…”

Supported Porous Nanomaterials as Efficient Heterogeneous Catalysts for CO2 Fixation Reactions

“…Sordakis et al. have reported a convenient catalytic pathway over a homogeneous iridium catalyst in which CO 2 can be directly reduced to formic acid (FA) under 20 bar pressure of CO 2 and 60 bar pressure of H 2 . Later FA can be selectively converted in the presence of H 2 SO 4 into methanol by a disproportionation in high yield.…”

Making a Splash in Homogeneous CO2 Hydrogenation: Elucidating the Impact of Solvent on Catalytic Mechanisms

“…Both of these approaches, indirect and direct conversion, require high temperatures (>130 °C) to obtain MeOH at a reasonable rate. One exception to the requirement of high temperature comes from Himeda and Laurenczy, who showed that direct hydrogenation of CO 2 to MeOH could be achieved at ambient temperature using [Cp*Ir(dhbp)(H 2 O)] 2+ (dhbp=4,4′‐dihydroxy‐2,2′‐bipyridine) as the catalyst in 2 M aqueous H 2 SO 4 (pH≈0) . The acidic conditions were critical for MeOH production, as the same Ir catalyst only produces formic acid at pH 3 …”