Electrochemical Hydrogenation of Soybean Oil with Hydrogen Gas

Developing electrochemical hydrogenation towards industrial application

Electrochemical hydrogenation reactions gained significant attention as a sustainable and efficient alternative to conventional thermocatalytic hydrogenations. This tutorial review provides a comprehensive overview of the basic principles, the practical application, and recent advances of electrochemical hydrogenation reactions, with a particular emphasis on the translation of these reactions from lab-scale to industrial applications. Giving an overview on the vast amount of conceivable organic substrates and tested catalysts, we highlight the challenges associated with upscaling electrochemical hydrogenations, such as mass transfer limitations and reactor design. Strategies and techniques for addressing these challenges are discussed, including the development of novel catalysts and the implementation of scalable and innovative cell concepts. We furthermore present an outlook on current challenges, future prospects, and research directions for achieving widespread industrial implementation of electrochemical hydrogenation reactions. This work aims to provide beginners as well as experienced electrochemists with a starting point into the potential future transformation of electrochemical hydrogenations from a laboratory curiosity to a viable technology for sustainable chemical synthesis on an industrial scale.

Production of partially hydrogenated soybean oil with low trans-fatty acids using surface dielectric barrier discharge cold plasma

This study examined the feasibility of applying surface dielectric barrier discharge cold plasma (SDBDCP) to partially hydrogenate crude soybean oil. The oil sample was treated for 13 h using SDBDCP at 15 kV with 100% hydrogen gas under room temperature and atmospheric pressure. Fatty acid composition, iodine value, refractive index, carotenoid content, melting point, peroxide value, and free fatty acids content (FFA) were investigated during SDBDCP treatment. Analysis of fatty acid composition demonstrated an increase in the content of saturated and monounsaturated fatty acids (from 41.32% to 55.3%) and a decrease in the content of polyunsaturated fatty acids (from 58.62% to 40.98%), which resulted in a reduction of the iodine value to 98.49 over the treatment time. Also, the fatty acid profile indicated that the total detected level of trans-fatty acids was very low (0.79%). After a 13-h treatment, the samples showed a refractive index of 1.4637, melting point of 10°C, peroxide value of 4.1 meq/kg, and FFA content of 0.8%. In addition, the results revealed a 71% decline in the carotenoid content of the oil sample due to the saturation of their double bonds. Therefore, these findings suggest that SDBDCP can be effectively used for hydrogenation along with bleaching oil.

Electrochemical hydrogenation of enones using a proton-exchange membrane reactor: selectivity and utility

Electrochemical hydrogenation of enones using a proton-exchange membrane reactor is described. The reduction of enones proceeded smoothly under mild conditions to afford ketones or alcohols. The reaction occurred chemoselectively with the use of different cathode catalysts (Pd/C or Ir/C).

Electrocatalytic Hydrogenation of Biomass-Derived Organics: A Review

Sustainable energy generation calls for a shift away from centralized, high-temperature, energy-intensive processes to decentralized, low-temperature conversions that can be powered by electricity produced from renewable sources. Electrocatalytic conversion of biomass-derived feedstocks would allow carbon recycling of distributed, energy-poor resources in the absence of sinks and sources of high-grade heat. Selective, efficient electrocatalysts that operate at low temperatures are needed for electrocatalytic hydrogenation (ECH) to upgrade the feedstocks. For effective generation of energy-dense chemicals and fuels, two design criteria must be met: (i) a high H:C ratio via ECH to allow for high-quality fuels and blends and (ii) a lower O:C ratio in the target molecules via electrochemical decarboxylation/deoxygenation to improve the stability of fuels and chemicals. The goal of this review is to determine whether the following questions have been sufficiently answered in the open literature, and if not, what additional information is required:(1)What organic functionalities are accessible for electrocatalytic hydrogenation under a set of reaction conditions? How do substitutions and functionalities impact the activity and selectivity of ECH?(2)What material properties cause an electrocatalyst to be active for ECH? Can general trends in ECH be formulated based on the type of electrocatalyst?(3)What are the impacts of reaction conditions (electrolyte concentration, pH, operating potential) and reactor types?

Electrochemical Hydrogen Production Using Separated-Gas Cells for Soybean Oil Hydrogenation

Although hydrogen is the most abundant element in the universe, it is not possible to find it in its purest state in nature. In this study, two-stage experimentation was carried out. The first stage was hydrogen production. The second stage was an electrochemical process to hydrogenate soybean oil in a PEM fuel cell. In the fist stage a Zirfon Perl UTP 500 membrane was used in an alkaline hydrolizer of separated gas to produce hydrogen, achieving 9.6 L/min compared with 5.1 L/min, the maximum obtained using a conventional membrane. The hydrogen obtained was used in the second stage to feed the fuel cell hydrogenating the soybean oil. Hydrogenated soybean oil showed a substantial diminished iodine index from 131 to 54.85, which represents a percentage of 58.13. This happens when applying a voltage of 90 mV for 240 min, constant temperature of 50 °C and one atm. This result was obtained by depositing 1 mg of Pt/cm 2 in the cathode of the fuel cell. This system represents a viable alternative for the use of hydrogen in energy generation.

Study on the Electrochemical Hydrogenation of Soybean Oil under H2 Conditions

The solubility of H₂ in electrolytes, H₂ reaction consumption and the conductivity of electrolytes under different pressures in an electrochemical hydrogenation reactor were studied. It was found that with an increase in H₂ pressure, H₂ was electrolyzed at the anode, accompanied by the generation of H⁺. The solubility of H₂ in the electrolytes and the conductivity of the electrolytes also increased. At first, the reaction consumption increased, followed by a tendency to be stable at 3 MPa. Therefore, the electrochemical hydrogenation of soybean oil was carried out at a H₂ pressure of 3 MPa. When the current was 120 mA, the temperature was 50°C, the agitation speed was 300 rpm, and the time was 7.5 h, the IV of hydrogenated soybean oil was 99.6 g I₂/100 g oil, and the TFA content of the oil was 4.3%.

Electrochemical Hydrogenation of Acetone to Produce Isopropanol Using a Polymer Electrolyte Membrane Reactor

Electrochemical hydrogenation (ECH) of acetone is a relatively new method to produce isopropanol. It provides an alternative way of upgrading bio-fuels with less energy consumption and chemical waste as compared to conventional methods. In this paper, Polymer Electrolyte Membrane Fuel Cell (PEMFC) hardware was used as an electrochemical reactor to hydrogenate acetone to produce isopropanol and diisopropyl ether as a byproduct. High current efficiency (59.7%) and selectivity (>90%) were achieved, while ECH was carried out in mild conditions (65 °C and atmospheric pressure). Various operating parameters were evaluated to determine their effects on the yield of acetone and the overall efficiency of ECH. The results show that an increase in humidity increased the yield of propanol and the efficiency of ECH. The operating temperature and power supply, however, have less effect. The degradation of membranes due to contamination of PEMFC and the mitigation methods were also investigated.

Ion-exchange membranes in chemical synthesis – a review

The applicability of ion-exchange membranes (IEMs) in chemical synthesis was discussed based on the existing literature. At first, a brief description of properties and structures of commercially available ion-exchange membranes was provided. Then, the IEM-based synthesis methods reported in the literature were summarized, and areas of their application were discussed. The methods in question, namely: membrane electrolysis, electro-electrodialysis, electrodialysis metathesis, ion-substitution electrodialysis and electrodialysis with bipolar membrane, were found to be applicable for a number of organic and inorganic syntheses and acid/base production or recovery processes, which can be conducted in aqueous and non-aqueous solvents. The number and the quality of the scientific reports found indicate a great potential for IEMs in chemical synthesis.

Effects of hydrophobicity of diffusion layer on the electroreduction of biomass derivatives in polymer electrolyte membrane reactors

For the first time, the hydrophobicity design of a diffusion layer based on the volatility of hydrogenation reactants in aqueous solutions is reported. The hydrophobicity of the diffusion layer greatly influences the hydrogenation performance of two model biomass derivatives, namely, butanone and maleic acid, in polymer electrolyte membrane reactors operated at atmospheric pressure. Hydrophobic carbon paper repels aqueous solutions, but highly volatile butanone can permeate in vapor form and achieve a high hydrogenation rate, whereas, for nonvolatile maleic acid, great mass transfer resistance prevents hydrogenation. With a hydrophilic stainless-steel welded mesh diffusion layer, aqueous solutions of both butanone and maleic acid permeate in liquid form. Hydrogenation of maleic acid reaches a similar level as that of butanone. The maximum reaction rate is 340 nmol cm(-2)  s(-1) for both hydrogenation systems and the current efficiency reaches 70 %. These results are better than those reported in the literature.

Selective Electrocatalytic Hydrogenation of Linolenic Acid onPd/Al2O3andPd-Co/Al2O3Catalysts

Electrochemical hydrogenation of linolenic acid as a model for polyunsaturated acids was studied on Pd and Pd/Al2O3catalysts in acidic and alkaline media. The results are presented in terms of number of double bonds in the polyunsaturated fatty acid and interpreted in terms of the adsorption capacity of the catalysts in these media. The highest hydrogenation yield was obtained with Pd/Al2O3at pH 13, in good correlation with the adsorption power of linolenic acid and its first hydrogenation product, linoleic acid, measured in this solution. A preliminary electrochemical hydrogenation study was conducted on Pd/Al2O3catalyst containing Co, in the optimum electrolysis conditions, showing a cooperative effect of the noble metals regarding thecis/transselectivity with preferential formation ofcis-oriented monounsaturated compound. All the products were characterized by gas chromatography after derivatization of the samples; fifteencis-transisomers of monounsaturated fatty acid which could be identified are presented here.