Continuous electroreduction of CO2 towards formate in gas-phase operation at high current densities with an anion exchange membrane

The carbon dioxide (CO2) electroreduction to formate is nowadays considered as a promising approach to convert CO2 into a value-added product and simultaneously, in the context of strategies for mitigating climate change. However, there is a scarce number of studies published in the literature operating with a current density higher than 200 mA cm- 2 , and there is the need of operating at higher current densities, with acceptable performance and low penalty in terms of energy consumption, for future implementation at industrial scale. Thus, in this work, a novel configuration is studied using a filter press reactor in a continuous mode, with a single pass of the reactants through the cell, employing a Sustainion anion exchange membrane and working with a current density up to 600 mA cm-2 . Using the same electrocatalysts, the configuration shows a similar performance to the GDE configuration with liquid electrolyte, but with the advantage of operating only with a vapour input to the cathode and avoiding the need for a liquid catholyte. Although at the expense of obtaining a more diluted product, excellent combinations of Faradaic Efficiency for formate (73.7 %), energy consumptions (342 kWh-kmol-1), and product rates (22.9 mmol m- 2 -s -1) can be achieved at high current densities. Therefore, the configuration with Sustainion membranes reported in this manuscript can be particularly interesting for future applications that do not involve a very concentrated formate product.Authors fully acknowledge the financial support received from the Spanish State Research Agency (AEI) through the projects PID2019-108136RB-C31 (AEI/10.13039/501100011033) and PID2020-112845RB-I00 (AEI/10.13039/501100011033). We are also grateful for the nanoparticles prepared and provided by the group of Prof. V. Montiel and Dr. José Solla-Gullón from the Institute of Electrochemistry of the University of Alicante. The authors also thank BioRender.com online software as this science illustration tool has allowed to create some of the figures of this manuscript

Continuous electrochemical reduction of CO2 to formate: comparative study of the influence of the electrode configuration with Sn and Bi-based electrocatalysts

Climate change has become one of the most important challenges in the 21st century, and the electroreduction of CO2 to value-added products has gained increasing importance in recent years. In this context, formic acid or formate are interesting products because they could be used as raw materials in several industries as well as promising fuels in fuel cells. Despite the great number of studies published in the field of the electrocatalytic reduction of CO2 to formic acid/formate working with electrocatalysts of different nature and electrode configurations, few of them are focused on the comparison of different electrocatalyst materials and electrode configurations. Therefore, this work aims at presenting a rigorous and comprehensive comparative assessment of different experimental data previously published after many years of research in different working electrode configurations and electrocatalysts in a continuous mode with a single pass of the inputs through the reactor. Thus, the behavior of the CO2 electroreduction to formate is compared operating with Sn and Bi-based materials under Gas Diffusion Electrodes (GDEs) and Catalyst Coated Membrane Electrodes (CCMEs) configurations. Considering the same electrocatalyst, the use of CCMEs improves the performance in terms of formate concentration and energy consumption. Nevertheless, higher formate rates can be achieved with GDEs because they allow operation at higher current densities of up to 300 mA·cm-2. Bi-based-GDEs outperformed Sn-GDEs in all the figures of merit considered. The comparison also highlights that in CCME configuration, the employ of Bi-based-electrodes enhanced the behavior of the process, increasing the formate concentration by 35% and the Faradaic efficiency by 11%.The authors gratefully acknowledge the Spanish Ministry of Economy and Competitiveness, through the project CTQ2016-76231-C2-1-R (AEI/FEDER, UE) for financial support

Integration of chemical engineering skills in the curriculum of a master course in industrial engineering

Promoting new teaching methodologies is essential to improve the participation, motivation, interest, and results of students in all educational stages. In this sense, flipped classroom and problem-based learning have emerged in the last years as fascinating options to be implemented in high education levels thanks to the students’ maturity and previously acquired background. Working with motivating case studies based on real processes with their restrictions appears as an opportunity to bring future professionals closer to the industrial problems; this will capacitate engineers to solve and understand complex procedures getting tangible results. In this context, the main goal of this work is to combine flipped classroom and problem-based learning methodologies to gain the interest of students of a Master course in Industrial Engineering in the subject of Chemical Processes using real data of local companies. A survey, designed by the academics involved, will help collecting the opinion of students as well as the acquired skills in the frame of the specific subject. Results demonstrated the satisfaction of the students with the course, highlighting mainly the acquisition or improvement of self-learning skills (survey 4.0/5.0), capacity for organization and planning (survey 4.0/5.0), analytical ability (survey 4.2/5.0), and teamwork (survey 4.3/5.0). In addition, the grades accomplished during the year of implementation show that although the success rate is quite similar to preceding years, the marks achieved are considerably higher

Electroreduction of CO2: advances in the continuous production of formic acid and formate

The study of the electrochemical CO2 reduction to obtain formate (HCOO–) or formic acid (HCOOH) is receiving much attention as a promising technology. Since continuous–mode operation has become necessary for practical implementation of electrochemical CO2 reduction, recent years have seen a rapid increase in the number of research approaches focusing on this aspect. This Focus Review provides a unified discussion of the available studies on the continuous electroreduction of CO2 to HCOO–/HCOOH, considering the different important features of process design. Moreover, this paper quantitatively assesses the performance of different studies that involve continuous electrochemical reactors for converting CO2 to HCOOH/HCOO–, comparing relevant typically used figures of merit, including energy consumption. Although some relevant trade-offs have already been achieved, the simultaneous optimization of all the figures of merit remains a challenge. Finally, concluding remarks highlight the detected trends and discuss relevant aspects that will have to be tackled by future studies in this field.The authors acknowledge the financial support from the Spanish State Research Agency (AEI) through the projects PID2019-108136RB-C31 and PID2020-112845RB-I00 (MCIN/AEI/10.13039/501100011033)

Sistema de reacción para conversión de CO2

La presente invención está relacionada con la transformación del CO2 a productos de interés, tales como el formiato (HCOO¯) mediante un reactor el electroquímico tipo filtro prensa mejorado y adaptado para su uso en un aparato electroquímico. El reactor electroquímico tipo filtro prensa y su uso en un aparato electroquímico proporciona HCOO¯ con alta eficiencia (EF), alta concentración y velocidad de producción de HCOO¯ a la vez que se disminuye el consumo energético.Solicitud: 202030174 (28.02.2020)Nº Pub. de Solicitud: ES2823929A1 (10.05.2021

Single-Pass Electrooxidation of Glycerol on Bismuth-Modified Platinum Electrodes as an Anodic Process Coupled to the Continuous CO2 Electroreduction toward Formate

CO2 electroreduction has emerged as a promising strategy for reducing emissions while simultaneously generating valuable products, particularly formic acid/formate. To further enhance the sustainability of this process, the traditional oxygen evolution reaction at the anode can be replaced by a more interesting reaction like glycerol oxidation to high value-added products, in a covalorization approach. In this study, the effect of the presence of a bismuth (Bi) atom supplier (Bi2O3 particles) in the anolyte solution during the glycerol electrooxidation process on platinum (Pt) electrodes coupled with the electroreduction of CO2 to formate is investigated for the first time, operating in a continuous mode with a single pass through the reactor. The results reveal that in the cathode, significant HCOO– production, with Faradaic efficiencies reaching 93%, and modest energy consumption of 208 kW h·kmol–1 were obtained in the continuous CO2 electroreduction to formate using Bi gas diffusion electrodes. On the other hand, in the anode, the presence of Bi2O3 particles leads to a significant alteration in the distribution of high-value-added oxidation products obtained. For instance, the anode demonstrates remarkable dihydroxyacetone (DHA) production of 283 μmol·m–2·s–1, surpassing the results obtained with the nonmodified Pt electrodes. The performance of this system offers a promising pathway for the simultaneous coproduction of high-value-added products from both CO2 and glycerol.The authors gratefully acknowledge the financial support through MCIN/AEI/10.13039/501100011033 projects PID2019-108136RB-C31 and PID2019-108136RB-C32

Coupling continuous CO2 electroreduction to formate with efficient Ni-based anodes

CO2 electroreduction to formic acid and formate has been focus of great research attention in the last years. Thus, considerable and relevant efforts have been accomplished in this field, mainly by operating with different types of catalysts and electrode configurations in the cathodic compartment. Still, Pt-based anodes, which are expensive and scarce, are typically the preferred materials to carry out the oxygen evolution reaction in alkaline medium. However, it is crucial to search for new materials of lower prices, with high stability, and good performances able to be competitive with traditional Pt-based electrodes. Hence, we study hand-made NiO-based anodes for the continuous CO2 electroreduction for formate in a filter press reactor with a single pass of the reactants through the electrochemical reactor. The use of the NiO-based anodes enhances the results obtained in previous studies with DSA/O2 anodes, combining excellent values of Faradaic Efficiency for formate of 100 %, and energy consumptions values close to only 200 kWh·kmol-1. In addition, employing Sustainion® as a binder in the fabrication of the anode results in a significant improvement in the durability, maintaining similar performance in terms of key metrics.Authors fully acknowledge the financial support received from the Spanish State Research Agency (AEI) through the projects PID2019-108136RB-C31 and PID2020-112845RB-I00 (AEI/10.13039/501100011033). We are also grateful for the Bi carbon-supported nanoparticles prepared and provided by the group of Prof. V. Montiel and Dr. José Solla-Gullón from the Institute of Electrochemistry of the University of Alicante. Guillermo Díaz-Sainz would like to thank the Academic Planning and Teaching Staff Vice-chancellorship of University de Cantabria and the Young Chemical Researchers Group, belonging to the Royal Spanish Society of Chemistry (JIQ-RSEQ) for financial help to carry out the research stay at the Faculty of Engineering of the University of Porto in which the present work was developed

Automatic ankle angle detection by integrated RGB and depth camera system

Depth cameras are developing widely. One of their main virtues is that, based on their data and by applying machine learning algorithms and techniques, it is possible to perform body tracking and make an accurate three-dimensional representation of body movement. Specifically, this paper will use the Kinect v2 device, which incorporates a random forest algorithm for 25 joints detection in the human body. However, although Kinect v2 is a powerful tool, there are circumstances in which the device’s design does not allow the extraction of such data or the accuracy of the data is low, as is usually the case with foot position. We propose a method of acquiring this data in circumstances where the Kinect v2 device does not recognize the body when only the lower limbs are visible, improving the ankle angle’s precision employing projection lines. Using a region-based convolutional neural network (Mask RCNN) for body recognition, raw data extraction for automatic ankle angle measurement has been achieved. All angles have been evaluated by inertial measurement units (IMUs) as gold standard. For the six tests carried out at different fixed distances between 0.5 and 4 m to the Kinect, we have obtained (mean ± SD) a Pearson’s coefficient, r = 0.89 ± 0.04, a Spearman’s coefficient, ρ = 0.83 ± 0.09, a root mean square error, RMSE = 10.7 ± 2.6 deg and a mean absolute error, MAE = 7.5 ± 1.8 deg. For the walking test, or variable distance test, we have obtained a Pearson’s coefficient, r = 0.74, a Spearman’s coefficient, ρ = 0.72, an RMSE = 6.4 deg and an MAE = 4.7 deg.This work has been supported by the Spanish Ministry of Science, Innovation and Universities and European Regional Development Fund (ERDF) across projects RTC-2017-6321-1 AEI/FEDER, UE, PID2019-107270RB-C21 AEI/FEDER, UE and FEDER founds

Continuous carbon dioxide electroreduction to formate coupled with the single-pass glycerol oxidation to high value-added products

CO2 electroreduction has been considered a promising alternative to simultaneously reduce CO2 emissions and produce value-added products. Among others, the production of formic acid/formate is particularly attractive. Although promising results have already been obtained in the literature, one of the recent approaches to improve the process deals with the use of an alternative reaction at the anode instead of the traditional oxygen evolution reaction (OER). In this context, this work reports, for the first time, the study of the CO2 electroreduction to formate coupled with the electrooxidation of glycerol to high-added value products where both half-reactions operate in a continuous mode with a single pass of the reactants through the electrochemical cell. Interestingly, at the cathode, similar results to those previously reported were obtained, reaching formate concentrations of about 18 g·L-1 at a 200 mA·cm-2. In addition, at the anode, promising dihydroxyacetone productions of 196 µmol·m-2·s-1 were simultaneously achieved in the output stream of the anodic compartment. These findings represent a significant step forward for the development and application of the technology.The authors gratefully acknowledge financial support through projects PID2019–108136RB-C31, PID2019–108136RB-C32 and PID2020–112845RB-I00 (AEI/10.13039/501100011033)

Optimized manufacturing of gas diffusion electrodes for CO2 electroreduction with automatic spray pyrolysis

Despite being one of the most promising CO2 utilization strategies some aspects still hinder the scaling up of CO2 electroreduction processes. One of them is the fabrication of the electrodes, which is currently rudimentary and depends fundamentally on the human factor. Here, we report an automated spray pyrolysis technique coupled with a plasma surface treatment to fabricate Bi-based gas diffusion electrodes for a enhanced CO2 electroreduction to formate. Three fabrication parameters, namely i) spraying nozzle height, ii) step distance, and iii) ink flow rate, are evaluated to determine the optimal fabrication conditions. The results confirm the reproducibility of the fabrication method, improving the overall performance of the electrodes fabricated with a manual airbrushing method, and leading to formate rates of up to 10.1 mmol m-2 s-1 at 200 mA cm-2. Besides, plasma treatment can improve formate concentration by up to 12 % in comparison with the untreated electrode. As a result, this work provides novel insights into the development of more efficient methods to manufacture electrodes for CO2 electroreduction, which will eventually bring this technology closer to an industrial scale.The authors fully acknowledge the financial support received from the Spanish State Research Agency (AEI) through the projects PID2020-112845RB-I00, TED2021–129810B-C21, PID2019-104050RA-I00, and PLEC2022-009398 (MCIN/AEI/10.13039/501100011033). Jose Antonio Abarca gratefully acknowledges the predoctoral research grant (FPI) PRE2021-097200