Gábor Laurenczy

Efficient Dehydrogenation of Formic Acid Using an Iron Catalyst

Iron-catalyzed hydrogen generation raises prospects for a cheap hydrogen storage medium. Hydrogen is one of the essential reactants in the chemical industry, though its generation from renewable sources and storage in a safe and reversible manner remain challenging. Formic acid (HCO2H or FA) is a promising source and storage material in this respect. Here, we present a highly active iron catalyst system for the liberation of H2 from FA. Applying 0.005 mole percent of Fe(BF4)2·6H2O and tris[(2-diphenylphosphino)ethyl]phosphine [P(CH2CH2PPh2)3, PP3] to a solution of FA in environmentally benign propylene carbonate, with no further additives or base, affords turnover frequencies up to 9425 per hour and a turnover number of more than 92,000 at 80°C. We used in situ nuclear magnetic resonance spectroscopy, kinetic studies, and density functional theory calculations to explain possible reaction mechanisms.

Formic acid as a hydrogen source – recent developments and future trends

Formic acid has recently been suggested as a promising hydrogen storage material. The basic concept is briefly discussed and the recent advances in the development of formic acid dehydrogenation catalysts are shown. Both the state of research for heterogeneous and for homogeneous catalyst systems are reviewed in detail and an outlook on necessary development steps is presented. Formic acid is considered as one of the most promising materials for hydrogen storage today. There are a number of highly active and robust homogeneous catalysts that selectively decompose formic acid to H2 and CO2 near to room temperature. Although the activity and selectivity of heterogeneous catalysts have not yet reached the level of homogeneous systems, this gap is closing.

A Well-Defined Iron Catalyst for the Reduction of Bicarbonates and Carbon Dioxide to Formates, Alkyl Formates, and Formamides

Keywords: carbon dioxide ; formate ; homogeneous catalysis ; hydrogenation ; iron ; Formic-Acid ; Homogeneous Hydrogenation ; Aqueous-Solution ; Metal-Complexes ; Dihydrogen ; Efficient ; Ketones ; Co2 ; Hydrosilylation ; Conversion Reference EPFL-ARTICLE-172116doi:10.1002/anie.201004263View record in Web of Science Record created on 2011-12-16, modified on 2017-05-12

Direct synthesis of formic acid from carbon dioxide by hydrogenation in acidic media

The chemical transformation of carbon dioxide into useful products becomes increasingly important as CO2 levels in the atmosphere continue to rise as a consequence of human activities. In this article we describe the direct hydrogenation of CO2 into formic acid using a homogeneous ruthenium catalyst, in aqueous solution and in dimethyl sulphoxide (DMSO), without any additives. In water, at 40 °C, 0.2 M formic acid can be obtained under 200 bar, however, in DMSO the same catalyst affords 1.9 M formic acid. In both solvents the catalysts can be reused multiple times without a decrease in activity. Worldwide demand for formic acid continues to grow, especially in the context of a renewable energy hydrogen carrier, and its production from CO2 without base, via the direct catalytic carbon dioxide hydrogenation, is considerably more sustainable than the existing routes.

Hydrogen storage: beyond conventional methods.

The efficient storage of hydrogen is one of three major hurdles towards a potential hydrogen economy. This report begins with conventional storage methods for hydrogen and broadly covers new technology, ranging from physical media involving solid adsorbents, to chemical materials including metal hydrides, ammonia borane and liquid precursors such as alcohols and formic acid.

Selective Formic Acid Decomposition for High‐Pressure Hydrogen Generation: A Mechanistic Study

A homogenous catalytic system has been developed that efficiently and selectively decomposes formic acid into hydrogen and carbon dioxide. [Ru(H(2)O)(6)](2+), [Ru(H(2)O)(6)](3+) and RuCl(3) x xH(2)O are all excellent pre-catalysts in presence of TPPTS (TPPTS = meta-trisulfonated triphenylphosphine), the formic acid decomposition taking place in the aqueous phase, under mild conditions and over a large range of pressures. Optimisation of the reaction conditions is described together with a detailed mechanistic study leading to a tentative catalytic cycle. The performance of the catalytic system for continuous hydrogen generation is presented. Overall, the method proposed overcomes the limitations of other catalysts for the decomposition of formic acid making it a viable hydrogen-storage material.

Homogeneous hydrogenation of carbon dioxide and bicarbonate in aqueous solution catalyzed by water-soluble ruthenium(II) phosphine complexes

The water-soluble Ru(II)-phosphine complex, [{RuCl2(mTPPMS)(2)}(2)] was found a suitable catalyst for the hydrogenation of NaHCO3 to NaHCO2 in aqueous solution under mild conditions with catalyst turnover frequencies (TOFs) in the range of 35-50 h(-1) at 50degreesC and 10 bar total pressure. The suggested reaction mechanism involves the formation of Ru(II)-hydrides of the general formula [RuHX(mTPPMS)(4)] where X = H-, HCO3- or HCO2-. At 80degreesC and 95 bar total pressure, the reduction of NaHCO3 proceeded with high reaction rate (9600 h(-1)) hitherto unobserved in purely aqueous solutions. The reactions do not require the presence of organic amine additives, however, the addition of quinoline increased the rate considerably. Aqueous suspensions of calcium carbonate could also be hydrogenated with CO2/H-2 gas mixtures

Metal‐Free Catalyst for the Chemoselective Methylation of Amines Using Carbon Dioxide as a Carbon Source

N-methylation of amines is an important step in the synthesis of many pharmaceuticals and has been widely applied in the preparation of other key intermediates and chemicals. Therefore, the development of efficient methylation methods has attracted considerable attention. In this respect, carbon dioxide is an attractive C1 building block because it is an abundant, renewable, and nontoxic carbon source. Consequently, we developed a highly chemoselective, metal-free catalytic system that operates under ambient conditions for the N-methylation of amines.

Ruthenium-Catalyzed Hydrogenation of Bicarbonate in Water

Hydrogenation of bicarbonates in water: By using a ruthenium-based catalytic system hydrogenation of sodium bicarbonate was achieved in water in comparable high TONs and yields. The hydrogenation of sodium bicarbonate takes place with the catalytic system without addition of carbon dioxide.

A Charge/Discharge Device for Chemical Hydrogen Storage and Generation

Keywords: fuel cells · homogeneous catalysis · hydrogen · hydrogenation · ruthenium Reference EPFL-ARTICLE-169668doi:10.1002/anie.201104951View record in Web of Science Record created on 2011-10-21, modified on 2017-05-12