The conversion of waste CO2 to value‐added chemicals through electrochemical reduction is a promising technology for mitigating climate change while simultaneously providing economic opportunities. The use of non‐aqueous solvents like methanol allows for higher CO2 availability and novel products. In this work, the electrochemistry of CO2 reduction in acidic methanol catholyte at a Pb working electrode was investigated while using a separate aqueous anolyte to promote a sustainable water oxidation half‐reaction. The selectivity among methyl formate (a product unique to reduction of CO2 in methanol), formic acid, and formate was critically dependent on the catholyte pH, with higher pH conditions leading to formate and low pH favoring methyl formate. The potential dependence of the product distribution in acidic catholyte was also investigated, with a faradaic efficiency for methyl formate as high as 75 % measured at −2.0 V vs. Ag/AgCl.

Electrochemical CO2 reduction has promise as a technology that could help society reach carbon neutrality while producing valuable fuels and chemicals. Herein, the electrochemical synthesis of methyl formate, a product not observed in aqueous CO2 electrolysis, has been analyzed by a rigorous technoeconomic model to evaluate its commercial viability. Methyl formate synthesis has been demonstrated with high faradaic efficiency through the electroreduction of CO2 in methanol. Four competing approaches were analyzed: (1) electroreduction of captured CO2 in a dual CH3OH/H2O electrolyzer, (2) direct electroreduction of flue gas CO2 in a dual CH3OH/H2O electrolyzer, (3) electroreduction of captured CO2 in a CH3OH/CH3OH electrolyzer, and (4) electroreduction of captured CO2 in a H2O/H2O electrolyzer with a downstream CH3OH reactor. Sensitivity analyses, cost contour plots, and comparison plots were generated. The dual methanol/water electrolysis approach was the most cost competitive, with a levelized cost of methyl formate below the present market price. The all-methanol electrolysis route was more expensive due to increased methanol consumption and greater distillation costs. Methyl formate production through aqueous CO2 electrolysis to formic acid with a secondary esterification reaction was by far the most expensive approach, primarily due to the energy-intensive nature of distilling formic acid from water.

Electrochemical CO 2 reduction from renewable energy is a promising route to mitigate greenhouse gas emissions from waste sources while generating value-added products. CO 2 electroreduction in methanol is particularly interesting due to the increased CO 2 solubility compared to water and the propensity to form methyl formate, a product absent in aqueous electrolysis. Four factors have been identified as critical to achieving prolonged high selectivity for methyl formate production on a Pb cathode in methanol: high pH near the electrode, low bulk pH, low water content, and regeneration of Pb 2+ sites. Increasing concentration of the formic acid product was observed to induce a selectivity shift toward hydrogen, which was mitigated by the in situ conversion of the formic acid to methyl formate via an esterification reaction. Furthermore, co-electrolysis of CO 2 with dilute molecular oxygen (4% O 2 ) led to Pb catalyst repair through in situ surface oxidation. Using CO 2 and dilute O 2 along with single-pass catholyte flow to maintain a low formic acid concentration, sustained high selectivity for methyl formate was attained at ∼60% faradaic efficiency at −20 mA cm −2 for over 72 h.

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This paper presents results of the Electrochemical Machining (ECM) process, which was used to machine the SS AISI 202. Specifically, the Material Removal Rate (MRR) and Surface Roughness (SR) as a function of ECM were determined. The experimental work was based on the Taguchi approach of experimentation and table L 32 was used. Furthermore, a theoretical and computational model is presented to illustrate the influence parameter variations in results. In addition to this the influence of independent parameters such as time of electrolysis, voltage, current, concentration of electrolyte, feed rate and pressure upon the amount of material removed and SR. The results indicated that MRR was remarkably affected by variation in current and Surface Roughness decreased with increase in current. Hence, it was apparent that irregular MRR was more likely to occur at high currents. The results showed that MRR increased with increasing electrical voltage, molar concentration of electrolyte, time of electrolysis and feed rate. However, the time of electrolysis was the most influential parameter on the produced surface finish.