Catalytic hydrogenation of organic carbonates, carbamates and formates is of significant interest both conceptually and practically, because these compounds can be produced from CO2 and CO, and their mild hydrogenation can provide alternative, mild approaches to the indirect hydrogenation of CO2 and CO to methanol, an important fuel and synthetic building block. Here, we report for the first time catalytic hydrogenation of organic carbonates to alcohols, and carbamates to alcohols and amines. Unprecedented homogeneously catalysed hydrogenation of organic formates to methanol has also been accomplished. The reactions are efficiently catalysed by dearomatized PNN Ru(II) pincer complexes derived from pyridine- and bipyridine-based tridentate ligands. These atom-economical reactions proceed under neutral, homogeneous conditions, at mild temperatures and under mild hydrogen pressures, and can operate in the absence of solvent with no generation of waste, representing the ultimate 'green' reactions. A possible mechanism involves metal-ligand cooperation by aromatization-dearomatization of the heteroaromatic pincer core.

Efficient hydrogenation of organic carbonates, carbamates and formates indicates alternative routes to methanol based on CO2 and CO

The activity and state of the copper surface in methanol synthesis catalysts

Methanol reforming for fuel-cell applications: development of zirconia-containing Cu–Zn–Al catalysts

Copper-Zinc Oxide-Alumina Methanol Catalysts Revisited

Oxide-supported noble metal catalysts were tested in the preferential oxidation of carbon monoxide (PROX) reaction in the temperature range between 50 and 300 °C. Both the influence of the noble metal nature (Pt, Ir, Pd), the support physical and chemical properties (redox, acidity, basicity) and the reaction conditions (oxygen stoichiometry) on the catalyst activity and selectivity was evaluated. Platinum and iridium were shown to be the most active and selective catalysts in the whole temperature range compared with palladium. Furthermore, noble metals supported over ceria-based oxides were shown to be active and selective, especially at low temperature. Additionally, it was observed that the higher the molar fraction in ceria in the oxide, the higher the activity and the selectivity in the PROX reaction. Ceria, with the highest oxygen mobility at the oxide surface, was shown to be the best support. Accordingly, on simple oxides (CeO2, SiO2–Al2O3, Al2O3, SiO2, La2O3 and MgO), the induced mobility of the oxygen atoms at the surface of the support determined elsewhere, well correlated with the basicity of the support, was shown to be one key parameter for the performances of the catalysts in the PROX reaction. Finally, the formation of water (hydrogen oxidation) at high temperature and high oxygen excess was shown to be responsible for the increasing activity of the catalysts in the conversion of CO to CO2 via the water gas shift reaction (WGSR).

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Noble metal catalysts for the preferential oxidation of carbon monoxide in the presence of hydrogen (PROX)

On the determination of copper surface area by reaction with nitrous oxide

Hydrogenolysis of alkyl formates over a copper chromite catalyst

Hydrogenolysis of ethyl formate to methanol and ethanol has been found to proceed at moderate temperatures and pressures. Copper-based catalysts having an open pore structure have the greatest activity and selectivity for the hydrogenolysis reaction. Small amounts of CO, CO2 and ethyl acetate are formed as byproducts at atmospheric pressure, but these are reduced by operation at higher hydrogen pressures.

J.W. Evans

Papers

On the determination of copper surface area by reaction with nitrous oxide

Hydrogenolysis of alkyl formates over a copper chromite catalyst

Hydrogenolysis of ethyl formate over copper-based catalysts

Kinetic studies of gas-phase hydrogenolysis of methyl formate to methanol over copper-based catalyst