Hydrolysis–Hydrogenation of Arabinogalactan Catalyzed by Ru/Cs3HSiW12O40.

The hydrolysis–hydrogenation of arabinogalactan hemicellulose to valuable polyalcohols arabitol and galactitol, which are widely used in the food and pharmaceutical industries, is studied. The possibility of using a bifunctional catalyst containing disperse ruthenium supported on cesium salt of heteropolyacid Ru/Cs₃HSiW₁₂O₄₀ for the process is demonstrated. A series of catalysts with different contents of the noble metal (0.3, 0.6 and 1 wt %) were prepared. Physicochemical techniques (low temperature nitrogen adsorption, IR spectroscopy, XRD, TEM) are used to characterize the prepared catalysts and the Cs₃HSiW₁₂O₄₀ support. The effect the temperature and the substrate : catalyst ratio, and the content of ruthenium in the catalyst, have on the yields of the target products is studied. The highest yields of arabitol and galactitol were observed for a catalyst containing 0.6 wt % of Ru at a substrate : catalyst ratio of 1 : 1. Arabitol and galactitol can be produced with yields of 12 and 48%, respectively, at 200°C in the presence of 0.6%Ru/Cs₃HSiW₁₂O₄₀ catalyst. [ABSTRACT FROM AUTHOR]