Electrochemical Hydrogenation Reaction of Toluene with PtxRu Alloy Catalyst-Loaded Gas Diffusion Electrodes

Abstract

We used the modified Bonnemann method to prepare PtxRu (x = 1, 3, and 4) alloy-loaded carbon black (PtxRu/C) catalysts. And we performed galvanostatic electrolysis with the gas diffusion electrodes (GDEs) including PtxRu/C in the catalyst layer to evaluate hydrogenation activity of toluene (TL) and analyze hydrogenation product qualitatively and quantitatively. From X-ray diffraction patterns and X-ray photoelectron spectra, it was found that Pt was alloyed with Ru. In the activation, the surface Ru atoms of each alloy partially dissolved, and the surface area of Pt increased. The Pt3Ru/C-loaded GDE had highest specific surface area after initial activation. In addition, the Pt3Ru/C-loaded GDE after initial activation exhibited the highest apparent current densities for the TL hydrogenation over the whole potential in this study, suggesting that the Pt3Ru/C-loaded GDE exhibited the highest hydrogenation activity. Gas chromatograph/mass spectrometric measurements showed the sole hydrogenation product of TL at the Pt3Ru/C-loaded GDE was methylcyclohexane (MCH). The total production amount of MCH increased with the reaction time. After the galvanostatic electrolysis for 2 h, the production of hydrogen was confirmed by gas chromatography. Then, MCH production and the faradaic efficiency for hydrogen evolution were 84.6 and 7.1%, respectively, so the total faradaic efficiency is 91.7%.