Energy-Saving Cathodic Hydrogen Production Enabled by Anodic Oxidation of Aqueous Sodium Sulfite Solutions (original) (raw)
2020, Energy & Fuels
The potential energy of SO 2 is wasted in the process of converting Na 2 SO 3 to Na 2 SO 4 via air oxidation during conventional treatment of SO 2-contaminated air. Considering that the oxidation of Na 2 SO 3 is thermodynamically and kinetically much easier than the oxygen evolution reaction (OER), this study proposes replacing the OER with Na 2 SO 3 oxidation to recover the potential energy of SO 2 and simultaneously reduce the energy consumption of water electrolysis. First, the influences of the reaction temperature and Na 2 SO 3 concentration on Na 2 SO 3-assisted water electrolysis (SAWE) were studied. Then, the difference between Na 2 SO 3 electrolysis and water electrolysis was compared under optimum conditions. Furthermore, the long-term stability of SAWE was assessed. The results of this study suggest that the onset potential of water electrolysis decreases from 0.73 V vs saturated calomel electrode (SCE) to 0.28 V vs SCE by replacing the OER with Na 2 SO 3 oxidation. The energy consumption of producing hydrogen by water electrolysis is reduced with the use of the potential energy of SO 2. For SAWE, the Na 2 SO 3 oxidation kinetics and hydrogen production rate are improved as the reaction temperature and Na 2 SO 3 concentration increase.
Related papers
An alternative approach to selective sea water oxidation for hydrogen production
Sea water electrolysis is one of the promising ways to produce hydrogen since it is available in plentiful supply on the earth. However, in sea water electrolysis toxic chlorine evolution is the preferred reaction over oxygen evolution at the anode. In this work, research has been focused on the development of electrode materials with a high selectivity for oxygen evolution over chlorine evolution. Selective oxidation in sea water electrolysis has been demonstrated by using a cation-selective polymer. We have used a perm-selective membrane (Nafion®), which electrostatically repels chloride ions (Cl−) to the electrode surface and thereby enhances oxygen evolution at the anode. The efficiency and behaviour of the electrode have been characterized by means of anode current efficiency and polarization studies. The surface morphology of the electrode has been characterized by using a scanning electron microscope (SEM). The results suggest that nearly 100% oxygen evolution efficiency could be achieved when using an IrO2/Ti electrode surface-modified by a perm-selective polymer.
Effect of operating parameters on hydrogen production by electrolysis of water
International Journal of Hydrogen Energy , 2017
This paper presents an experimental study of hydrogen production by alkaline water electrolysis using Zinc alloys as materials for cathode. The aim of this study is to select the best alloy for producing hydrogen on testing the effect of some operating parameters. Experiments were conducted on a water electrolysis cell with two electrodes (anode/ cathode). Throughout these experiments, we have chosen to use NaOH solution with different concentrations as an electrolyte. Binary alloys: Zn95%Fe5%, Zn90%Fe10%, Zn85% Fe15%, Zn95%Cu5%, Zn90%Cu10%, Zn85%Cu15%, Zn95%Co5%, Zn90%Co10%, Zn95%Cr5% and Zn90%Cr10% (mass %) were prepared as electrodes for the cathode. The effect of electrode composition, the electrolyte concentration, the voltage and amperage applied on volume of hydrogen produced are experimentally investigated. The results showed that the performance of alkaline water electrolysis is significantly affected by these various factors. Indeed, this preliminary study revealed that cathodes elaborated by (Zn95%Cr5%) and (Zn90%Cr10%) (mass %) produce more hydrogen gas than other alloys, in a minimum durations over the range of operating parameters tested.
ChemInform
Water electrolysis derived by renewable energy such as solar energy and wind energy is a sustainable method for hydrogen production due to high purity, simple and green process. One of the challenges is to reduce energy consumption of water electrolysis for large-scale application in future. Cell voltage, an important criterion of energy consumption, consists of theoretical decomposition voltage (U-theta), ohmic voltage drop (i*Sigma R) and reaction overpotential (eta). The kinetic and thermodynamic roots of high cell voltage are analyzed systemically in this review. During water electrolysis, bubble coverage on electrode surface and bubble dispersion in electrolyte, namely bubble effect, result in high ohmic voltage drop and large reaction overpotential. Bubble effect is one of the most key factors for high energy consumption. Based on the theoretical analysis, we summarize and divide recent intensification technologies of water electrolysis into three categories: external field, n...
Loading Preview
Sorry, preview is currently unavailable. You can download the paper by clicking the button above.