Jonathan Albo

Towards the electrochemical conversion of carbon dioxide into methanol

Various strategies have been proposed to date in order to mitigate the concentration of CO2 in the atmosphere, such as the separation, storage, and utilization of this gas. Among the available technologies, the electrochemical valorisation of CO2 appears to be an innovative technology, in which electrical energy is supplied to establish a potential between two electrodes, allowing CO2 to be transformed into value-added chemicals under mild conditions. It provides a method to recycle CO2 (in a carbon neutral cycle) and, at the same time, a way to chemically store the excess of renewable energy from intermittent sources, thus reducing our dependence on fossil fuels. Among the useful products that can be obtained, methanol is particularly interesting as a platform chemical, and it has gained renewed and growing attention in the research community. Accomplishments to date in the electroreduction of CO2 to methanol have been encouraging, although substantial advances are still needed for it to become a profitable technology able to shift society to renewable energy sources. This review presents a unified discussion of the significant work that has been published in the field of electrocatalytic reduction of CO2 to methanol. It emphasizes the aspects related to process design at different levels: cathode materials, reaction media, design of electrochemical cells, as well as working conditions. It then extends the discussion to the important conclusions from different electrocatalytic routes, and recommendations for future directions to develop a catalytic system that will convert CO2 to methanol at high process efficiencies.

Magnetic ionic liquids: synthesis, properties and applications

Magnetic ionic liquids are room temperature ionic liquids, which have paramagnetic properties by themselves without the need of adding magnetic particles. These paramagnetic properties are induced by the anion, the cation or both. Most common paramagnetic ionic liquids are those that contain transition metal or lanthanide complexes in their anion structure. These tuneable fluids present unique physicochemical properties, resulting in responsive materials to an external magnetic field. The reported studies on the synthesis and applications of magnetic ionic liquids have increased in the recent years. Therefore, this review attempts to highlight the achievements and current status concerning the synthesis, properties and main applications of magnetic ionic liquids, providing insights into this research frontier.

Ionic liquids in the electrochemical valorisation of CO2

The development of electrochemical processes for using captured CO2 in the production of valuable compounds appears as an attractive alternative to recycle CO2 and, at the same time, to store electricity from intermittent renewable sources. Among the different innovative attempts that are being investigated to improve these processes, the application of ionic liquids (ILs) has received growing attention in recent years. This paper presents a unified discussion of the significant work that involves the utilisation of ILs for the valorisation of CO2 by means of electrochemical routes. We discuss studies in which CO2 is used as one of the reactants to electrosynthesise value-added products, among which dimethyl carbonate has been the focus of particular attention in the literature. Approaches based on the electrochemical reduction of CO2 to convert it into products without the use of other carbon-based reactants are also reviewed, highlighting the remarkable improvements that the use of ILs has allowed in the CO2 electroreduction to CO. The review emphasises on different aspects related to process design, including the nature of IL anions and cations that have been used, the working conditions, the electrocatalytic materials, the electrode configurations, or the design of electrochemical cells, as well as discussing the most relevant observations, results and figures of merit that the participation of ILs has allowed to achieve in these processes. Several conclusions are finally proposed to highlight crucial challenges and recommendations for future research in this area.

Long-range magnetic ordering in magnetic ionic liquid: Emim[FeCl4].

Up to now most of the magnetic ionic liquids containing tetrachloroferrate ion FeCl(4) have evidenced a paramagnetic temperature dependence of the magnetic susceptibility, with only small deviations from the Curie law at low temperatures. However, we report on the physical properties of 1-ethyl-3-methylimidazolium tetrachloroferrate Emim[FeCl(4)], that clearly shows a long-range antiferromagnetic ordering below the Néel temperature T(N)≈3.8 K. In addition, the field dependence of the magnetization measured at 2 K is characterized by a linear behaviour up to around 40 kOe, while above this field the magnetization becomes saturated with a value of 4.3 μ(B)/Fe, which is near the expected fully saturated value of 5 μ(B)/Fe for an Fe(3+) ion.

Copper‐Based Metal–Organic Porous Materials for CO2 Electrocatalytic Reduction to Alcohols

The electrocatalytic reduction of CO2 has been investigated using four Cu-based metal-organic porous materials supported on gas diffusion electrodes, namely, (1) HKUST-1 metal-organic framework (MOF), [Cu3 (μ6 -C9 H3 O6 )2 ]n ; (2) CuAdeAce MOF, [Cu3 (μ3 -C5 H4 N5 )2 ]n ; (3) CuDTA mesoporous metal-organic aerogel (MOA), [Cu(μ-C2 H2 N2 S2 )]n ; and (4) CuZnDTA MOA, [Cu0.6 Zn0.4 (μ-C2 H2 N2 S2 )]n . The electrodes show relatively high surface areas, accessibilities, and exposure of the Cu catalytic centers as well as favorable electrocatalytic CO2 reduction performance, that is, they have a high efficiency for the production of methanol and ethanol in the liquid phase. The maximum cumulative Faradaic efficiencies for CO2 conversion at HKUST-1-, CuAdeAce-, CuDTA-, and CuZnDTA-based electrodes are 15.9, 1.2, 6, and 9.9 %, respectively, at a current density of 10 mA cm-2 , an electrolyte-flow/area ratio of 3 mL min cm-2 , and a gas-flow/area ratio of 20 mL min cm-2 . We can correlate these observations with the structural features of the electrodes. Furthermore, HKUST-1- and CuZnDTA-based electrodes show stable electrocatalytic performance for 17 and 12 h, respectively.

Tailoring gas-phase CO2 electroreduction selectivity to hydrocarbons at Cu nanoparticles

Copper-based surfaces appear as the most active catalysts for CO2 electroreduction to hydrocarbons, even though formation rates and efficiencies still need to be improved. The aim of the present work is to evaluate the continuous gas-phase CO2 electroreduction to hydrocarbons (i.e. ethylene and methane) at copper nanoparticulated-based surfaces, paying attention to particle size influence (ranging from 25-80 nm) on reaction productivity, selectivity, and Faraday efficiency (FE) for CO2 conversion. The effect of the current density and the presence of a microporous layer within the working electrode are then evaluated. Copper-based gas diffusion electrodes are prepared by airbrushing the catalytic ink onto carbon supports, which are then coupled to a cation exchange membrane (Nafion) in a membrane electrode assembly. The results show that the use of smaller copper nanoparticles (25 nm) leads to a higher ethylene production (1148 μmol m-2 s-1) with a remarkable high FE (92.8%), at the same time, diminishing the competitive hydrogen evolution reaction in terms of FE. This work demonstrates the importance of nanoparticle size on reaction selectivity, which may be of help to design enhanced electrocatalytic materials for CO2 valorization to hydrocarbons.

Synthesis of heterometallic metal–organic frameworks and their performance as electrocatalyst for CO2 reduction

Herein we report the solventless synthesis and doping of the benchmark HKUST-1(Cu) as a facile route to afford heterometallic metal–organic frameworks (MOFs) having proficient behavior as electrocatalytic materials in the reduction of carbon dioxide. Zn(II), Ru(III) and Pd(II) were selected as doping metals (MD) with the aim of partially replacing the Cu(II) atoms of the pristine structure to afford HKUST-1(Cu,MD) type materials. Apart from the high yield and good crystallinity of the obtained materials, the extremely high reagent concentration that the reaction conditions imply makes it feasible to control dopant loading in all cases. Prepared samples were processed as electrodes and assembled in a continuous flow filter-press electrochemical cell. Faraday efficiency to methanol and ethanol at Ru(III)-based electrodes resulted in activity as high as 47.2%, although the activity of the material decayed with time. The interplay of the dopant metal and copper(II), and the long-term performance are also discussed.

Electrochemical Conversion of CO2 to Value-Added Products

Abstract Climate change mitigation requires the development of new processes to reduce the amount of carbon dioxide in the atmosphere. The products of CO2 utilization can supplement or replace chemical feedstocks, fine chemicals, pharmaceutical, and polymers. Carbon capture and utilization based on innovative electroreduction processes is one of the suggested routes to reduce the use of coal and oil as carbon sources due to the recycling of carbon. Some chemicals may be produced using carbon dioxide, decreasing the use of natural resources. The electrocatalytic processes to obtain formate and methanol as derived products from CO2 are discussed in this chapter, taking into account the electro-catalysts and the reactor design in the development of innovative processes.

Modelling and process integration of carbon dioxide capture using membrane contactors

Abstract A zero solvent emission process is proposed using a membrane device and an ionic liquid as a solvent; integrating a non-dispersive absorption-desorption process, gas compression, and transport to sequestration area analysis. The study is based on a model of a hollow fibre module formulated with a system of partial differential equations in axial and radial directions, depending of the Graetz (Gz), solvent selection (H) and Sherwood (S h ) numbers. Numerical absorption results showing carbon dioxide (CO 2 ) recovery costs are presented, comparing them with those obtained in an integrated conventional process where Monoethanolamine (MEA) is applied as absorbent liquid.