Tsuneto Furuta

Electrochemical Synthesis of Sodium Peroxycarbonate at Boron-Doped Diamond Electrodes

An electrochemical method for the preparation of sodium peroxycarbonate at boron-doped diamond anodes has been described. Effects of experimental conditions such as current density, electrolyte concentration and anode materials on the formation of sodium peroxycarbonate have been investigated. The maximum current efficiency for producing sodium peroxycarbonate was found to be 82% at a current density of 0.05 A cm - 2 after 30 min of electrolysis in a solution of 1 M Na 2 CO 3 . The minimum energy consumption was found to be 2.2 Wh g - 1 at a current density of 0.05 A cm - 2 . The X-ray powder diffraction pattern was obtained in order to identify the products. The products were also analyzed using TG/DTA in order to determine the melting point.

Synthesis of peroxyacetic acid using in situ electrogenerated hydrogen peroxide on gas diffusion electrode

Abstract Peroxyacetic acid (PAA) has been first prepared from acetic acid in the presence of solid superacid, Nafion-H, as a catalyst at ambient temperature and atmospheric pressure using gas diffusion electrode (GDE) as an oxygen cathode. Hydrogen peroxide was electrogenerated by the reduction of oxygen on the GDE and PAA could be produced by a redox reaction between electrogenerated hydrogen peroxide and acetic acid. The continuous operation was carried out to examine the electrolysis performance of the present electrolysis system. The results demonstrate that the system can be continuously operated over one month with the production of PAA of ca. 1.9–2.3 mM.

Electrolytic Synthesis of Peroxyacetic Acid Using In Situ Generated Hydrogen Peroxide on Gas Diffusion Electrodes

An electrochemical method for the preparation of peroxyacetic acid (PAA) using in situ generated hydrogen peroxide on the gas diffusion electrode (GDE) as an oxygen cathode has been described. Effects of several experimental conditions, such as current density, oxygen feed rate, electrolyte concentration, electrolytic cell configuration, flow rate of electrolyte solution, and Pt catalyst incorporated into GDE upon the cathodic reaction of oxygen to hydrogen peroxide as well as the production of PAA solution, have been investigated. Hydrogen peroxide is electrogenerated by the reduction of oxygen on the GDE and the generated hydrogen peroxide can undergo a chemical reaction with acetic acid in the presence of solid superacid, Nafion-H as a catalyst to produce PAA. It is also suggested that the formation of PAA is initiated by the active oxygen, O*, electrogenerated on the cathode surface. The current efficiency for the production of PAA was found to be 28% at a current density of 1 A/dm 2 and electrolyte flow rate of 160 mL/h. A probable reaction mechanism for the formation of PAA is proposed.

A new method for the preparation of peroxyacetic acid using solid superacid catalysts

A new method for the preparation of peroxyacetic acid from acetic acid and hydrogen peroxide in the presence of solid superacids as a catalyst under mild conditions has been proposed. The preparation of peroxyacetic acid could be carried out in a batchwise operation as well as in a flow-system operation. Nafion-H was found to be active and very stable catalyst for the preparation of peroxyacetic acid and to be regenerated without the loss of catalytic activity.

Effect of solvent and hydrogen during selective hydrogenation

Abstract Described is the solvent effect for the chemoselective hydrogenation of alkenes having a benzyloxy group (Bn-O-) using a hydrogenation system employing atomic hydrogen permeating through a Pd sheet electrode.

Reduction of nitrate ion using hydrogen permeating Pd foil electrodes

The successive electrochemical reduction system using hydrogen-permeable Pd foil electrodes with Pd black catalyst was applied to reduction of nitrate ion. It was revealed that the second metals co-deposited to Pd black catalyst showed an excellent selectivity for decomposition of NO3− to N2, and was stable for at least 200 days. This system employing a compact and a simple electrolysis cell is expected to be an alternative or a supplement to conventional biological treatments for nitrate removal.

Electrolysis of (CH3)4NF•5HF Melt with Boron-doped Diamond Anode

Introduction Although electrolytic synthesis of (CF3)3N was conducted by Simons method, this process had a few disadvantages. One of them was an operation at temperatures less than 0 degree Celsius. Use of a room temperature molten salt (CH3)4NF·mHF as electrolyte enables to solve this problem. Recently, electrolysis of the (CH3)4NF·mHF melt using the Ni anode has been developed for electrolytic synthesis of (CF3)3N. In this case, electrolysis was stopped for shorter duration because of formation of NiF2 film on the Ni anode. Hence, it is necessary to develop a new anode for electrolytic production of (CF3)3N from only the (CH3)4NF·mHF melt. Since Boron-doped diamond (BDD) has a high electric conductivity and stability of structure such as diamond, it is expected that BDD electrode can be used as a new anode material in this process. Hence, the performance of a BDD anode for electrolytic production of (CF3)3N was investigated in the (CH3)4NF·mHF melt. Experimental A room temperature molten salt of (CH3)4NF·5HF was used as an electrolyte. Electrochemical measurements and electrolysis were carried out in a three-electrode cell. Anode potential was determined galvanostatically in the range of current density from the 5 mA cm to 100 mA cm in the (CH3)4NF·5HF melt with BDD and Ni electrodes. Electrolysis of the (CH3)4NF·5HF melt was conducted at 40 or 100 mA cm for 200h at room temperature with BDD electrode. The anode gas was analyzed by gas chromatography mass spectroscopy and gas chromatography. The anode surface after electrolysis was also analyzed by X-ray diffraction (XRD). Result and discussion Fig. 1 shows the galvanostatic polarization curves of BDD electrode and Ni electrode in the (CH3)4NF·5HF. In the Ni electrode, anode potential was larger even at low current density. On the other hand, anode potential increased slightly with increasing current density and no anode effect took place at 100 mA cm in the BDD electrode. The compositions of anode gas evolved at the BDD anode in electrolysis of the (CH3)4NF·5HF melt at room temperature are shown in Table 1. The anode gas was composed of CF4, NF3, CHF3, CH2F2, C2F6, (CF3)3N, (CF3)2CHF2N, CF3(CHF2)2N, and (CHF2)3N. The ratios of (CF3)3N and (CF3)2CHF2N increased with increasing current density. This result suggests that electrolytic fluorination may be promoted at high current density. XRD patterns of the BDD anodes before and after electrolysis are shown in Fig. 2. Both XRD patterns have (1 1 1) peak and (2 2 0) peak. They are assigned to BDD. The structure of BDD was maintained after electrolysis. From these results, the electrolytic production of (CF3)3N from (CH3)4NF·5HF melt using the BDD anode is an appropriate process because the electrolytic conductivity of BDD anode surface is kept higher during electrolysis.

A Fabrication Method for MEAs for PEFCs Using Nafion Precursor

A fabrication method of membrane electrode assemblies (MEAs) for polymer electrolyte fuel cells (PEFCs) using a thin preformed precursor sheet has been described. A preformed precursor sheet was sandwiched between two gas-diffusion electrodes, and the resulting precursor electrode assembly is hot pressed at 150°C for 2 min. Due to thermoplastic property of the precursor sheet, the catalyst layer of the gas-diffusion electrode may be embedded into the preformed precursor sheet and more effective three-phase boundaries are formed. The MEAs prepared by the present method give, in single-cell tests at 75°C, current density of 0.4 A cm - 2 at 0.5 V.

Effect of Electrolyte Composition and Anode Material on Current Efficiency for NF3 Formation in Electrolytic Synthesis using Diamond Anode

The current efficiency for NF3 formation was investigated using Boron-Doped Diamond (BDD) anode in NH4FnHF melts. It depended on both the current density and the NH4F-concentration. The best current efficiency was obtained at 40 mA/cm2 and the NH4F-concentration of 33.3 mol% (the NH4F2HF melt), and its value was 72.4%.