Yulei Zhu

Graphene oxide as a facile acid catalyst for the one-pot conversion of carbohydrates into 5-ethoxymethylfurfural

Graphene oxide obtained by the Hummers method was discovered to be an efficient and recyclable acid catalyst for the conversion of fructose-based biopolymers into 5-ethoxymethylfurfural (EMF). EMF yields of 92%, 71%, 34% and 66% were achieved when 5-hydroxymethylfurfural (HMF), fructose, sucrose and inulin were used as starting materials, respectively.

Efficient catalytic system for the conversion of fructose into 5-ethoxymethylfurfural

DMSO can improve the selectivity of 5-hydroxymethylfurfural (HMF) in the conversion of carbohydrates. However, one of the bottlenecks in its application is product separation. Thus a one-pot synthesis of 5-ethoxymethylfurfural (EMF) rather than HMF from fructose in ethanol-DMSO was investigated. Phosphotungstic acid was used as an effective catalyst. The yield of EMF can be reached as high as 64% in the mixed solvent system of DMSO and ethanol within 130 min at 140 °C. Ethyl levulinate (LAE) was detected as the main by-product, the yield of which increased with the reaction time, temperature and the amount of catalyst. In addition, the existence of water could significantly reduce the yield of EMF and increased the yield of LAE. Most importantly, it was discovered that EMF could be much more efficiently extracted from the reaction solvent system by some organic solvents than HMF.

Production of bioadditives from glycerol esterification over zirconia supported heteropolyacids.

The synthesis of bioadditives for biofuels from glycerol esterification with acetic acid was performed over zirconia supported heteropolyacids catalysts using H(4)SiW(12)O(40) (HSiW), H(3)PW(12)O(40) (HPW) and H(3)PMo(12)O(40) (HPMo) as active compounds. The as-prepared catalysts were characterized by N(2)-physisorption, XRD, Raman spectroscopy, NH(3)-TPD, FTIR of pyridine adsorption and H(2)O-TPD. Among the catalysts tested, HSiW/ZrO(2) achieved the best catalytic performance owing to the better combination of surface Brønsted acid sites and hydrothermal stability. A 93.6% combined selectivity of glyceryl diacetate and glyceryl triacetate with complete glycerol conversion was obtained at 120°C and 4h of reaction time in the presence of HSiW/ZrO(2). This catalyst also presented consistent activity for four consecutive reaction cycles, while HPW/ZrO(2) and HPMo/ZrO(2) exhibited distinct deactivation after reusability tests. In addition, HSiW/ZrO(2) can be resistant to the impurities present in bulk glycerol.

One-step hydrogenolysis of glycerol to biopropanols over Pt–H4SiW12O40/ZrO2 catalysts

The one-step hydrogenolysis of biomass-derived glycerol to propanols (1-propanol + 2-propanol), which are known as biopropanols, was investigated over different supported Pt–H4SiW12O40 (HSiW) bi-functional catalysts in aqueous media. Among the catalysts/supports tested, Pt–HSiW supported over ZrO2 converted glycerol to biopropanols with high selectivity and high yield (94.1%), while exhibiting long-term stability (160 h). In addition, this catalyst can be resistant to the impurities present in crude glycerol. The reaction pathway to propanols from glycerol is proposed to proceed mainly through 1,2-propanediol. With the strategy toward one-step hydrogenolysis of glycerol to biopropanols sustainably, the biomass can be readily transformed to biodiesel and biopropanols via glycerol, which will bring about the benign development of the biodiesel industry.

Rational design of Ni-based catalysts derived from hydrotalcite for selective hydrogenation of 5-hydroxymethylfurfural

Selective hydrogenation of 5-hydroxymethylfurfural (HMF) is of great importance for future energy and chemical supply. Herein, we propose for the first time that non-noble Ni-Al2O3 catalysts derived from hydrotalcite-like compounds can efficiently and selectively convert HMF into 2,5-dimethylfuran (DMF), 2,5-dimethyltetrahydrofuran (DMTHF) and 2,5-dihydroxymethyltetrahydrofuran (DHMTHF). Homogeneous elemental distributions of the hydrotalcite-like precursor facilitate good dispersion of Ni and Al2O3 species and strong interaction between them over the resulting catalysts. The catalysts therefore exhibited superior reactivity. Through fine modulation of surface metal–acid bifunctional sites and control of reaction conditions, high yields of DMF (91.5%), DMTHF (97.4%) and DHMTHF (96.2%) can be diversely achieved. The results demonstrate the feasibility of Ni catalysts for selective hydrogenation of CO, CC and C–O bonds, which have great potential for biomass utilization.

Selective conversion of furfuryl alcohol to 1,2-pentanediol over a Ru/MnOx catalyst in aqueous phase

The aqueous-phase hydrogenolysis of furfuryl alcohol (FFA) to 1,2-pentanediol (1,2-PeD) was carried out on a series of supported Ru catalysts and MnOx supported Pt, Pd and Rh catalysts. The Ru/MnOx catalysts showed high selectivity for 1,2-PeD, while the Pd and Rh catalysts displayed high selectivity for tetrahydrofurfuryl alcohol. The function of MnOx, the effects of solvent, temperature, H2 pressure and reaction time were further investigated. The support MnOx in the Ru/MnOx catalysts not only suppressed the polymerization of the FFA, but also enhanced the 1,2-PeD selectivity. Low pressure and high temperature favoured the generation of 1,2-PeD, and water significantly enhanced the reaction rate. At 150 °C, 1.5 MPa, the yield of 1,2-PeD was up to 42.1% over the Ru/MnOx catalyst. The proposed mechanism for FFA hydrogenolysis in aqueous medium over the Ru/MnOx catalyst is suggested to occur via a partially hydrogenated intermediate.

Graphene Oxide Catalyzed Dehydration of Fructose into 5‐Hydroxymethylfurfural with Isopropanol as Cosolvent

The design of green heterogeneous catalysts for the efficient conversion of biomass into platform molecules is a key aim of sustainable chemistry. Graphene oxide prepared from Hummers oxidation of graphite was proven to be a green and efficient carbocatalyst for the dehydration of fructose into 5‐hydroxymethylfurfural (HMF) in some three‐carbon and four‐carbon alcohol mediated solvent systems. HMF was obtained in up to 87 % yield in 90 vol % isopropanol‐mediated DMSO solvent. Some control experiments and analytical data showed that a small number of sulfonic groups and abundance of oxygen‐containing groups (alcohols, epoxides, carboxylates) have an important synergic effect in maintaining the high performance of graphene oxide.

A highly efficient and robust Cu/SiO2 catalyst prepared by the ammonia evaporation hydrothermal method for glycerol hydrogenolysis to 1,2-propanediol

A highly efficient and robust Cu/SiO2 catalyst from a pure-phase copper phyllosilicate precursor was successfully fabricated by the ammonia evaporation hydrothermal (AEH) method. The impregnation (IM) Cu/SiO2 catalyst was prepared for comparison. The structure, morphologies, thermal stability and surface chemical state of these catalysts were comprehensively characterized by ICP, BET, XRD (in situ XRD), N2O chemisorption, H2-TPR, IR and Raman spectroscopy, TEM and XPS. Compared to the IM sample, the AEH catalyst was exceedingly highly active and stable (300 h) for glycerol hydrogenolysis to 1,2-propanediol. The unprecedented catalytic performance was attributed to the strong interaction between Cu and SiO2 species derived from copper phyllosilicate, well-dispersed Cu nanoparticles and the cooperative effect of Cu0 and Cu+. Moreover, active Cu0 species were identified as the primary active sites for glycerol hydrogenolysis, as corroborated by the strong correlation between 1,2-propanediol yield and Cu surface area.

Water‐Promoted Hydrogenation of Levulinic Acid to γ‐Valerolactone on Supported Ruthenium Catalyst

A highly efficient and green process for the hydrogenation of biomass‐derived levulinic acid (LA) to γ‐valerolactone (GVL) has been developed. GVL was obtained in a yield of 99.9 mol % with a turnover frequency as high as 7676 h−1 in aqueous medium by using a Ru/TiO2 catalyst under mild reaction conditions (70 °C). The strong interaction between Ru and TiO2 facilitated both the dispersion of Ru nanoparticles and the stability of the catalyst. In addition, as solvent, water participated in the hydrogenation of LA, which was confirmed by an isotope‐ labeling experiment with D (D2O). Specifically, the H atom(s) in water took part in the hydrogenation of the CO group of LA, which promoted the catalytic activity and GVL yield remarkably.

A new strategy for the efficient synthesis of 2-methylfuran and γ-butyrolactone

A novel process involving the coupling of the hydrogenation of furfural and the dehydrogenation of 1,4-butanediol has been studied in the vapor phase for the synthesis of 2-methylfuran (2-MF) and γ-butyrolactone (γ-BL) over the same Cu-based catalyst. It was found that hydrogen and heat energy are utilized with high efficiency in this process.