Owing to the increasing emissions of carbon dioxide (CO2), human life and the ecological environment have been affected by global warming and climate changes. To mitigate the concentration of CO2 in the atmosphere various strategies have been implemented such as separation, storage, and utilization of CO2. Although it has been explored for many years, hydrogenation reaction, an important representative among chemical conversions of CO2, offers challenging opportunities for sustainable development in energy and the environment. Indeed, the hydrogenation of CO2 not only reduces the increasing CO2 buildup but also produces fuels and chemicals. In this critical review we discuss recent developments in this area, with emphases on catalytic reactivity, reactor innovation, and reaction mechanism. We also provide an overview regarding the challenges and opportunities for future research in the field (319 references).

Recent advances in catalytic hydrogenation of carbon dioxide

Catalysis for the valorization of exhaust carbon: from CO2 to chemicals, materials, and fuels. technological use of CO2.

The Golden Age of Transfer Hydrogenation

The direct and catalyzed electrochemistry of CO2 partake in the contemporary attempts to reduce this inert molecule to fuels by means of solar energy, either directly, after conversion of light to electricity, or indirectly in that all elements of comprehension derived from electrochemical experiments can be used in the design and interpretation of photochemical experiments. Following reviews of the activity in the field until 2007–2008, the present review reports more recent findings even if their interpretation remains uncertain. It also develops useful notions that allow analyzing and comparing more rigorously the performances of existing catalysts when the necessary data are available. Among the general trends that transpire presently and are likely to be the object of active future work emphasis is put on the favorable role of acid addition in homogeneous catalytic systems and on the crucial chemical role of the electrode material in heterogeneous catalysis.

Catalysis of the electrochemical reduction of carbon dioxide

Photoand Electrochemical CO2 Reduction Wan-Hui Wang,*,† Yuichiro Himeda,*,‡,§ James T. Muckerman, Gerald F. Manbeck, and Etsuko Fujita* †School of Petroleum and Chemical Engineering, Dalian University of Technology, Panjin 124221, China ‡National Institute of Advanced Industrial Science and Technology, Tsukuba Central 5-1, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan JST, ACT-C, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973-5000, United States

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CO2 Hydrogenation to Formate and Methanol as an Alternative to Photo- and Electrochemical CO2 Reduction

This tutorial review describes recent progress in the development of homogeneous catalytic methodology for the direct generation of hydrogen gas from formic acid and alcohols.

Hydrogen generation from formic acid and alcohols using homogeneous catalysts

Ruthenium dimer 6 (readily available in two steps from TsDPEN) is converted directly to monomeric asymmetric transfer hydrogenation catalyst 3 in situ under the conditions employed for ketone reduction. Catalyst 3 is a significantly more active catalyst for this application than the untethered derivative, exhibits higher enantioselectivities across a range of substrates, and appears to be highly stable to the reaction conditions. It is active at loadings of as low as 0.01 mol %, and reductions at the 0.1 mol % level are complete within 20 min at 80 °C without significant loss of enantioselectivity.

A class of ruthenium(II) catalyst for asymmetric transfer hydrogenations of ketones.

The attachment of a tethering group from the basic nitrogen atom to the arene ligand of a ruthenium(II) catalyst greatly improves its ability to catalyze asymmetric transfer hydrogenation (ATH) reactions. In this paper, we describe further applications of this versatile system to an extended substrate range.

David J. Morris

Papers

Hydrogen generation from formic acid and alcohols using homogeneous catalysts

A class of ruthenium(II) catalyst for asymmetric transfer hydrogenations of ketones.

The "reverse-tethered" ruthenium (II) catalyst for asymmetric transfer hydrogenation: further applications.

A stereochemically well-defined rhodium(III) catalyst for asymmetric transfer hydrogenation of ketones.

Insights into hydrogen generation from formic acid using ruthenium complexes