BACKGROUND Glycerol, which is a coproduct of biodiesel production, has been identified as a key platform compound for producing various valuable chemicals. The selective catalytic oxidation of glycerol to dihydroxyacetone is very attractive. RESULTS A series of Au catalysts supported on metallic oxides, i.e. ZnO, CuO, Al2O3, Fe2O3 and NiO, were studied for selective catalytic oxidation of glycerol to dihydroxyacetone under base‐free conditions. Among the catalysts, Au/CuO showed the best catalytic activity (glycerol conversion of 89% and dihydroxyacetone selectivity of 82.6% at 80 °C under 10 bar of O2), followed by Au/ZnO ≫ Au/NiO > Au/Al2O3 ≈ Au/CuO‐SD ≈ Au/Fe2O3. The catalytic behaviors of these supported Au catalysts varied depending on the Au particle size, Au oxidation state, Au–support interactions and lattice oxygen reducibility. CONCLUSION The main reasons for the high catalytic activity of Au/CuO are as follows. Firstly, the catalyst has small metallic Au particles, which are more active in cleavage of the secondary CH bond in glycerol molecules. Secondly, the interactions between Au and CuO facilitate lattice oxygen reduction, and this increases oxygen mobility, which may promote regeneration of Au–support perimeter active sites by gaseous oxygen. © 2019 Society of Chemical Industry

BACKGROUND Glycerol is a versatile platform compound to produce valuable chemicals. One‐pot direct conversion of glycerol into methyl lactate with methanol as solvent is very attractive, because it can reduce intermediate steps and avoid the separation of glycerol/methanol mixtures. RESULTS A series of tin (Sn)‐exchanged montmorillonite(M)‐supported Au catalysts were prepared by a combination of ion exchange and colloidal deposition methods, and designed as bifunctional catalysts containing gold (Au) and solid acid. These catalysts were employed for one‐pot conversion of glycerol to methyl lactate in methanol. The Au/Sn(20)‐Mt catalyst gave a high yield of methyl lactate of 54% upon conversion of 0.25 mol L–1 glycerol methanol solution over 0.07 g catalyst at 210 °C under 3 MPa air for 5 h. The good performance of Au/Sn(20)‐Mt was ascribed to the coexistence of small Au particle and abundance of acid sites. The glycerol conversion remained almost unchanged in the five recycled runs, whereas the methyl lactate yield decreased after the first run but kept stably in the later four catalytic runs. CONCLUSIONS Among the series of Sn‐exchanged Mt‐supported Au catalysts, Au/Sn(20)‐Mt showed the highest glycerol conversion and methyl lactate yield. Containing both small Au particles and having an abundance of acid sites contributed to the excellent catalytic activity of Au/Sn(20)‐Mt. © 2019 Society of Chemical Industry

BACKGROUND: The chemical catalytic conversion of carbohydrates into -valerolactone (GVL) is a sustainable alternative to the petrochemical process starting from the depleting fossil resources. Direct conversion of carbohydrates (fructose, glucose, starch and cellulose) into GVL was achieved via the combined heteropoly acid based SO 3 H-functionalized ionic liquid (HAIL) and supported ruthenium (Ru) catalyst system in one pot and in water media. RESULTS: A 63% GVL yield (based on fructose) was obtained under the catalysis of 1-methyl-3-(3-sulfopropylimidazolium) silicotungstate ([MIMPS] 4 SiW) and Ru/ZrO2 at 180 ∘ C, first in 0.1 MPa nitrogen (N 2 ) for 3 h (dehydration), and then in 4 MPa hydrogen (H 2 ) for 10 h (hydrogenation). Under the same reaction conditions, the GVL yields from glucose, starch and cellulose were 68%, 60% and 60%, respectively. The recyclability of the catalytic system consisting of [MIMPS] 4 SiW and Ru/ZrO 2 was investigated in four runs. The activity for [MIMPS] 4 SiW did not change after use. Partial deactivation of Ru/ZrO 2 was observed, which was ascribed to the severe carbon deposition.CONCLUSIONS: In the present method, HAIL and Ru/ZrO 2 catalysts were loaded together. No separation and/or neutralization step reported in the literature was needed and only an atmosphere change (from N 2 to H 2 ) step was involved. Therefore, we provide a promising method for efficient conversion of carbohydrates into GVL.

A series of SO42−/W−Zr catalysts with different W/Zr mole ratios were synthesized by solvent evaporation self‐assembly followed by impregnation of sulfuric acid. The catalysts were examined in the glycerol esterification with acetic acid, and fully characterized by XRD, BET, TEM, XPS, NH3‐TPD, H2O‐TPD and pyridine adsorption infrared spectroscopy. The results revealed that W/Zr mole ratio and calcination temperature significantly affected the structure, acidity and catalytic performance of the catalysts. SO42−/W−Zr(1:1)‐500 (with a W/Zr mole ratio of 1:1, calcined at 500 °C) exhibited the highest catalytic activity, which is mainly due to the fact that the catalyst had more acidic sites and good water tolerance. In addition, the catalyst also showed excellent recyclability, in five repeated runs the conversion of glycerol and yields of products remained stable.