The need to reduce the accumulation of CO2 into the atmosphere requires new technologies able to reduce the CO2 emission. The utilization of CO2 as a building block may represent an interesting approach to synthetic methodologies less intensive in carbon and energy. In this paper the general properties of carbon dioxide and its interaction with metal centres is first considered. The potential of carbon dioxide as a raw material in the synthesis of chemicals such as carboxylates, carbonates, carbamates is then discussed. The utilization of CO2 as source of carbon for the synthesis of fuels or other C1 molecules such as formic acid and methanol is also described and the conditions for its implementation are outlined. A comparison of chemical and biotechnological conversion routes of CO2 is made and the barriers to their exploitation are highlighted.

Utilisation of CO2 as a chemical feedstock: opportunities and challenges

Bicarbonate ion is an effective activator for hydrogen peroxide in the oxidation of sulfides. Kinetic and spectroscopic results support the formation of peroxymonocarbonate ion (HCO4-) as the oxidant in the catalytic reactions. The reaction of hydrogen peroxide and bicarbonate to form HCO4- occurs rapidly at 25 °C (t1/2 ≈ 300 s) near neutral pH in aqueous solution and alcohol/water mixtures, and an equilibrium analysis of the reaction by 13C NMR leads to an estimate of the electrode potential for the HCO4-/HCO3- couple (1.8 V vs NHE). Solubility of the bicarbonate catalyst is enhanced by the use of NH4HCO3 rather than by the use of group 1 salts, which tend to have lower solubility in the mixed solvents and can lead to phase separation. Rate laws and mechanistic analyses are presented for the oxidation of ethylphenylsulfide and related sulfides. The second-order rate constants for sulfide oxidations by HCO4- are ∼300-fold greater than those for H2O2, and this increase is consistent with expectations based...

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Equilibria, Kinetics, and Mechanism in the Bicarbonate Activation of Hydrogen Peroxide: Oxidation of Sulfides by Peroxymonocarbonate

This critical review describes the reactivity of heterogeneous catalysts from the point of view of four simple, but essential for Chemistry, molecules (namely dihydrogen, carbon monoxide, nitrogen monoxide and ethylene) that are considered as probes or as reactants in combination with “in situ” controlled temperature and pressure Infrared spectroscopy. The fundamental properties of H2, CO, NO and C2H4 are shortly described in order to justify their different behaviour in respect of isolated sites in different environments, extended surfaces, clusters, crystalline or amorphous materials. The description is given by considering some “key studies” and trying to evidence similarities and differences among surfaces and probes (572 references).

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Probing the surfaces of heterogeneous catalysts by in situ IR spectroscopy

State of the art and perspectives in catalytic processes for CO2 conversion into chemicals and fuels: The distinctive contribution of chemical catalysis and biotechnology

The utilization of CO2 as a soft oxidant and promoter is a promising concept for industrial applications that could not only contribute to the mitigation of CO2 levels, but also the development of economical and energy efficient syntheses of various chemicals. The abundant availability, non-toxic, economic and mild oxidizing properties of CO2 has resulted in immense interest in its use as an oxidant in several reactions, such as the oxidative coupling of CH4 and the oxidative dehydrogenation of alkanes and alkyl aromatics. At present, only a few processes based on CO2 as a soft oxidant have been realised on a technical scale in spite of dedicated research. This review is intended to trace the emergence, application and understanding of such systems and shed light on the further development that may lead to industrial scale operations in the near future.

Carbon dioxide utilization as a soft oxidant and promoter in catalysis

Extended labeling experiments have shown that formation of rhodium peroxocarbonate from CO2 and [RhCl(η2-O2)(P)3] (P is PEt2Ph or PEtPh2) proceeds through O−O bond cleavage and CO2 insertion. O-transfer to ancillary phosphine ligand to give R3PO selectively (>85%) involves the Rh-linked O atom of the peroxo group of RhCl(CO4)(P)3.

Mechanism of Formation of Peroxocarbonates RhOOC(O)O(Cl)(P)(3) and Their Reactivity as Oxygen Transfer Agents Mimicking Monooxygenases. The First Evidence of CO(2) Insertion into the O-O Bond of Rh(eta(2)-O(2)) Complexes.

The cocondensation products of nickel atoms with pure ethylene or ethylene-argon futures trapped at 12 K were reinvestigated by IR and UV-visible spectroscopies. The first Raman spectra were obtained. Isotopic H/D experiments and comparison of IR and Raman spectra indicate unambiguously that three complexes are formed, Ni(C 2 H 4 ) 3 , Ni(C 2 H 4 ) 2 , and Ni(C 2 H 4 ), with a normal order of increasing perturbation of ethylene vibration modes from the 1:3 to the 1:1 stoichiometries

Florence Galan

Papers

Mechanism of Formation of Peroxocarbonates RhOOC(O)O(Cl)(P)(3) and Their Reactivity as Oxygen Transfer Agents Mimicking Monooxygenases. The First Evidence of CO(2) Insertion into the O-O Bond of Rh(eta(2)-O(2)) Complexes.

Raman infrared, and UV-visible studies of matrix-isolated nickel(0) complexes with ethylene, propylene, and butadiene