Catalytic Reduction Of Carbon Dioxide Research Articles

Aromaticity as stabilizing element in the bidentate activation for the catalytic reduction of carbon dioxide.

A new transition-metal-free mode for the catalytic reduction of carbon dioxide via bidentate interaction has been developed. In the presence of Li2[1,2-C6H4(BH3)2], CO2 can be selectively transformed to either methane or methanol, depending on the reducing agent. The bidentate nature of binding is supported by X-ray analysis of an intermediate analogue, which experiences special stabilization due to aromatic character in the bidentate interaction. Kinetic studies revealed a first-order reaction rate. The transformation can be conducted without any solvent.

Function of the Support and Metal Loading on Catalytic Carbon Dioxide Reduction Using Ruthenium Nanoparticles Supported on Carbon Nanofibers

AbstractCatalytic CO2 reduction has been performed using carbon nanofibers or nitrogen‐doped carbon nanofibers as a support for Ru nanoparticles. The catalyst that consists of 5 wt % Ru on nitrogen‐doped carbon nanofibers exhibited the highest conversion at a relatively low temperature, complete selectivity to CH4, and stable catalytic performance. The catalytic performance was substantially superior to catalysts supported on carbon nanotubes and akin to the best metal‐oxide‐supported catalyst in the literature. The characterization of the prepared catalyst by transient experiments (CO2 temperature‐programmed desorption, temperature‐programmed surface reaction, and transient response to CO2 removal) revealed that the catalyst support participates actively in the reaction. The Ru content governed the selectivity, which either favored CO formation for lower Ru contents (0.5–2 wt %) or CH4 formation for 5 wt % Ru loading. The mean Ru particle size determined by TEM was similar for each of the metal loadings. Therefore, the substantially different selectivity patterns cannot be attributed to structure sensitivity. The higher selectivity to CH4 can be explained by the enhanced supply of adsorbed hydrogen to the activated adsorbed CO intermediate, which was demonstrated to be the rate‐determining step.

Cooperative Bond Activation and Catalytic Reduction of Carbon Dioxide at a Group 13 Metal Center

AbstractA single‐component ambiphilic system capable of the cooperative activation of protic, hydridic and apolar HX bonds across a Group 13 metal/activated β‐diketiminato (Nacnac) ligand framework is reported. The hydride complex derived from the activation of H2 is shown to be a competent catalyst for the highly selective reduction of CO2 to a methanol derivative. To our knowledge, this process represents the first example of a reduction process of this type catalyzed by a molecular gallium complex.

Cooperative bond activation and catalytic reduction of carbon dioxide at a group 13 metal center.

A single-component ambiphilic system capable of the cooperative activation of protic, hydridic and apolar HX bonds across a Group 13 metal/activated β-diketiminato (Nacnac) ligand framework is reported. The hydride complex derived from the activation of H2 is shown to be a competent catalyst for the highly selective reduction of CO2 to a methanol derivative. To our knowledge, this process represents the first example of a reduction process of this type catalyzed by a molecular gallium complex.

Theoretical study on the reaction mechanism of carbon dioxide reduction to methanol using a homogeneous ruthenium(II) phosphine catalyst

Quantum-chemical calculations using the density functional TPSS were carried out for the catalytic reduction of carbon dioxide to methanol using a ruthenium catalyst and hydrogen gas. Preparation of the active species as well as the catalytic cycle were modeled on the quantum-chemical level with solvent effects included by means of a continuum solvation model. Outer as well as inner sphere mechanisms were considered to gain insight into the details of carbon dioxide reduction using a ruthenium(II) catalyst. The overall Gibbs free reaction energy for CO2+3 H2→MeOH+H2O is computed to be −13.0kJ/mol. The highest reaction barrier (112.4kJ/mol) is found for the outer sphere hydrogen transfer from the active ruthenium species to carbon dioxide via a five-membered transition state structure.

Trapping Formaldehyde in the Homogeneous Catalytic Reduction of Carbon Dioxide

Trapping Formaldehyde in the Homogeneous Catalytic Reduction of Carbon Dioxide

Trapping Formaldehyde in the Homogeneous Catalytic Reduction of Carbon Dioxide

Trapping Formaldehyde in the Homogeneous Catalytic Reduction of Carbon Dioxide

Application of photo catalysis for mitigation of carbon dioxide

Photo catalytic reduction of carbon dioxide by water or artificial photosynthesis to yield hydrocarbons (methane and methanol, etc., termed “solar fuels”) is being studied extensively, with the twin objectives of developing an effective means of limiting atmospheric CO2 levels and evolving a sustainable alternative route for production of fuels and chemicals. This short review covers the origin and thermodynamic and kinetic features of the process, the basic photocatalytic principles involved, the rationale behind the choice of different catalysts and their performance, the effect of process conditions, the effect of the structural and photophysical properties of the different catalysts on their performance, mechanistic pathways, surface transformations, challenges involved in the practical application of the process, and future directions for research.

Tailoring Bimetallic Alloy Surface Properties by Kinetic Control of Self-Diffusion Processes at the Nanoscale

Achieving control of the nanoscale structure of binary alloys is of paramount importance for the design of novel materials with specific properties, leading to, for example, improved reaction rates and selectivity in catalysis, tailored magnetic behavior in electronics, and controlled growth of nanostructured materials such as graphene. By means of a combined experimental and theoretical approach, we show that the complex self-diffusion mechanisms determining these key properties can be mostly defined by kinetic rather than energetic effects. We explain how in the Ni-Cu system nanoscale control of self-diffusion and segregation processes close to the surface can be achieved by finely tuning the relative concentration of the alloy constituents. This allows tailoring the material functionality and provides a clear explanation of previously observed effects involved, for example, in the growth of graphene films and in the catalytic reduction of carbon dioxide.

Catalytic reduction of carbon dioxide into methanol over copper under hydrothermal conditions

A novel method for the catalytic synthesis of methanol from CO2 over Cu in the presence of Zn under hydrothermal conditions was investigated. The results showed Cu acts as an active catalyst in conversion of CO2 into methanol. The methanol yield of 11.4% was achieved at 350°C for 3h with Cu 70mmol, Zn 60mmol, HCl 2.0M and water filling 50%. The plausible mechanism for the hydrothermal conversion of CO2 into methanol was also discussed.

Pincer-Ligated Nickel Hydridoborate Complexes: the Dormant Species in Catalytic Reduction of Carbon Dioxide with Boranes

Nickel pincer complexes of the type [2,6-(R(2)PO)(2)C(6)H(3)]NiH (R = (t)Bu, 1a; R = (i)Pr, 1b; R = (c)Pe, 1c) react with BH(3)·THF to produce borohydride complexes [2,6-(R(2)PO)(2)C(6)H(3)]Ni(η(2)-BH(4)) (2a-c), as confirmed by NMR and IR spectroscopy, X-ray crystallography, and elemental analysis. The reactions are irreversible at room temperature but reversible at 60 °C. Compound 1a exchanges its hydrogen on the nickel with the borane hydrogen of 9-BBN or HBcat, but does not form any observable adduct. The less bulky hydride complexes 1b and 1c, however, yield nickel dihydridoborate complexes reversibly at room temperature when mixed with 9-BBN and HBcat. The dihydridoborate ligand in these complexes adopts an η(2)-coordination mode, as suggested by IR spectroscopy and X-ray crystallography. Under the catalytic influence of 1a-c, reduction of CO(2) leads to the methoxide level when 9-BBN or HBcat is employed as the reducing agent. The best catalyst, 1a, involves bulky substituents on the phosphorus donor atoms. Catalytic reactions involving 1b and 1c are less efficient because of the formation of dihydridoborate complexes as the dormant species as well as partial decomposition of the catalysts by the boranes.

Catalytic Generation of Hydrogen from Formic acid and its Derivatives: Useful Hydrogen Storage Materials

In this account the concept of using formic acid as a hydrogen storage material is presented. Catalytic reduction of carbon dioxide and heterogeneously catalyzed decomposition of formic acid to hydrogen and carbon dioxide are briefly discussed. In the main part the historic development and recent examples of homogeneously catalyzed hydrogen generation from formic acid are covered in detail.

Unexpected CO2 Splitting Reactions To Form CO with N-Heterocyclic Carbenes as Organocatalysts and Aromatic Aldehydes as Oxygen Acceptors

The catalytic reduction of carbon dioxide to carbon monoxide under mild conditions using aromatic aldehydes as reductants and NHCs as organocatalysts was developed. This carbon dioxide splitting reaction provides a new method for metal-free carbon dioxide reduction and steps forward in utilizing carbon dioxide as a renewable "green" source under mild conditions. On the other hand, this reaction also shows a new economical way to oxidize aromatic aldehydes under mild conditions with carbon dioxide and could be applied in pharmaceutical synthesis.

Electrocatalytic and homogeneous approaches to conversion of CO2to liquid fuels

Research in the field of catalytic reduction of carbon dioxide to liquid fuels has grown rapidly in the past few decades. This is due to the increasing amount of carbon dioxide in the atmosphere and a steady climb in global fuel demand. This tutorial review will present much of the significant work that has been done in the field of electrocatalytic and homogeneous reduction of carbon dioxide over the past three decades. It will then extend the discussion to the important conclusions from previous work and recommendations for future directions to develop a catalytic system that will convert carbon dioxide to liquid fuels with high efficiencies.

Kinetic modelling for photosynthesis of hydrogen and methane through catalytic reduction of carbon dioxide with water vapour

In a photocatalytic reduction process when products formed are not effectively desorbed, they could hinder the diffusion of intermediates on the surface of the catalyst, as well as increase the chance of collisions among the products, resulting photo-oxidation in a reserve reaction on the surface. This paper analyses a simple kinetic model incorporating the coupled effect of the adsorptive photocatalytic reduction and oxidation. The development is based on Langmuir–Hinshelwood mechanism to model the formation rates of hydrogen and methane through photocatalytic reduction of carbon dioxide with water vapour. Experimental data obtained from literatures have achieved a very good fit. Such model could aid as a tool for related areas of studies. A comparative study using the model developed, showed that product concentration in term of ppm would be an effective measurement of product yields through photocatalytic reduction of carbon dioxide with water vapour.

The catalytic reduction of carbon dioxide to carbon onion particles by platinum catalysts

The catalytic reduction of carbon dioxide to carbon onion particles by platinum catalysts

A concept for immobilizing catalytic complexes on electrodes: cubic phase layers for carbon dioxide sensing.

Liquid crystalline cubic phases formed with monoolein and Myverol have been used as matrixes to host a catalytic complex of nickel(II) and 1-hexadecyl-1,4,8,11-tetraazacyclotetradecane for the reduction of carbon dioxide. The structures of the cubic phases, both with and without the catalyst, were established using small-angle X-ray scattering. The catalytic reduction of carbon dioxide was performed using thin mercury film and glassy carbon electrodes modified with cubic phases containing the catalyst. The linear dependence of the catalytic reduction current on the carbon dioxide concentration allowed use of the modified electrodes as sensing devices both in solution and in the gas phase. The high reproducibility of the measurements makes this method of monitoring carbon dioxide levels attractive compared to other methods based on modified electrodes.

Carbon dioxide electrochemical sensor based on lipid cubic phase containing tetraazamacrocyclic complexes of Ni(II)

Liquid-crystalline cubic phases formed by polar lipids in an aqueous medium were used as hosting layers for catalytic tetraazamacrocyclic Ni(II) complexes. The role of the cubic phase is to hold the catalyst close to the electrode surface, to retain its catalytic activity and to provide suitable environment for the catalytic reaction. The properties of the cubic phase Q 224 (monoolein:water:catalyst) were investigated by microscopy with polarized light and electrochemical techniques. Nickel (II) complexes with derivatives of 1,4,8,11-tetraazacyclotetradecane were incorporated into bicontinuous cubic liquid-crystalline layer modifying the thin mercury film or glassy carbon electrode and used for the study of catalytic reduction of carbon dioxide. The reproducibility of the catalytic current of CO 2 reduction was found better than obtained using other methods based on modified electrodes. The linear dependence of catalytic reduction current on the concentration of CO 2 allowed the use of the system for carbon dioxide sensing in the solution. The sensor described in the present report was found useful also in case of CO 2 determination in the gas phase. In such environmentally interesting measurements, CO 2 was absorbed directly by the cubic phase in which the three electrodes: working, counter and reference were placed.

00/03392 Isolation of oxygen-formed during catalytic reduction of carbon dioxide using a solid electrolyte membrane

00/03392 Isolation of oxygen-formed during catalytic reduction of carbon dioxide using a solid electrolyte membrane

Bis-bipyridine hexa-aza-macrocycle complexes of zinc(II) and nickel(II) and the catalytic reduction of carbon dioxide

Aza-macrocyclic complexes have gained importance in catalysis for the activation of small molecules, like carbon dioxide. Bis-bipyridine hexa-aza-macrocycles efficiently co-ordinate as a tetradentate ligand, to give complexes of Zn(II), Ni(II) and other transition metal ions that are essentially planar. Spectroscopic, electrochemical and chemical characterizations of these systems are presented in this article. Electrochemical studies performed in a carbon dioxide atmosphere render preliminary information about its electrocatalytical reduction. Quantum chemical calculations are used to understand the origin of the manifested properties of both the ligands and the metal complexes. They show, in this case, the importance of delocalized π interactions, which are responsible for their different structural and electronic characteristics in protic and non-protic media.