Hydrogenation of lactic acid to propylene glycol over a carbon-supported ruthenium catalyst

•Ruthenium catalysts supported on various carbons were prepared using an incipient wetness impregnation method.•The ruthenium particle size is strongly dependent on the BET surface area of the carbon support.•Ru/ketjen black exhibited the highest catalytic activity for hydrogenation of lactic acid because of its fine dispersion of ruthenium.

Catalytic hydrogenation of lactic acid to propylene glycol is performed in a high-pressure batch reactor over ruthenium on various carbon supports (i.e., VulcanXC-72, ketjen black, CNTs, CNFs, and graphite) prepared using the incipient wetness impregnation method. The crystallinity of the synthesized catalyst is investigated via X-ray diffraction, and the particle sizes are determined using transmission electron microscopy. The surface areas of the synthesized catalysts are analyzed using the BET method; the catalytic activity correlates remarkably with the BET surface area. The yield of propylene glycol increases with pressure, and the highest yield is achieved at 130 °C. The catalytic activity is strongly dependent on the type of support. Among the catalysts tested, Ru on ketjen black shows the highest yield of propylene glycol.

Graphical abstractCatalytic activity of Ru is strongly dependent on carbon support.Figure optionsDownload full-size imageDownload high-quality image (60 K)Download as PowerPoint slide