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Duan Y.,Tsinghua University | Wu Y.,Tsinghua University | Wu Y.,Beijing Engineering Research Center for Biofuels | Shi Y.,Tsinghua University | And 3 more authors.
Catalysis Communications | Year: 2016

In this paper, SO4 2 -/Al2O3-SiO2 (SAS) was prepared and used for the esterification of octanoic acid with methanol. The effect of introduction of SiO2 was characterized by nitrogen sorption, ICP-AES, XRD, NH3-TPD, TG, FTIR and FTIR-pyridine adsorption. The results demonstrated that the doping of SiO2 resulted in the increase of BET surface areas and amount of surface sulfur species which led to an increase of acid sites especially Brönsted acid sites, which consequently boosted the catalytic esterification activity. In addition, the introduction of SiO2 can also increase the thermal stability of SO4 2 - and its interaction with Al2O3 support which resulted in the alleviation of catalyst deactivation. © 2016 Elsevier B.V. All rights reserved.

Tang Y.,Shihezi University | Tang Y.,Tsinghua University | Chen Y.,Tsinghua University | Wu Y.,Tsinghua University | And 5 more authors.
Microporous and Mesoporous Materials | Year: 2016

SBA-15 and metal doped SBA-15 with different metal special ratios were prepared using Pluronic P123 as a structure-directing agent. SBA-15 and metal doped SBA-15 were extensively characterized via N2 adsorption-desorption isotherm analysis, small-angle X-ray diffraction (SXRD), and Fourier transform infrared (FT-IR) analysis. The hydrothermal stability of the obtained mesoporous materials was tested in a stainless autoclave at 593 K for 1 h. Results of adsorption-desorption isotherm analysis, transmission electron microscopy, and SXRD revealed that metal doping improved the hydrothermal stability of SBA-15. Metal species and their molar ratios also contributed to the enhancement of hydrothermal stability. SXRD results showed that the diffraction peaks of metal doped SBA-15 shifted to higher 2θ degrees possibly because of framework constriction. FT-IR results indicated that the decrease in doped SBA-15 surface hydroxyl groups and hydrophilicity may be responsible for the improvement in hydrothermal stability after the introduction of heteroatoms. This work may serve as a reference for exploiting mesoporous materials with a hydrothermal stability and catalytic performance under aqueous conditions at high temperatures. © 2016 Elsevier Inc. All rights reserved.

Yu M.,Tsinghua University | Li J.,Tsinghua University | Chang S.,Tsinghua University | Du R.,Tsinghua University | And 7 more authors.
Energies | Year: 2014

Ethanol production from NaOH-Pretreated solid state fermented sweet sorghum bagasse with an engineered strain of Z. mobilis TSH-ZM-01 was optimized. Results showed that: (1) residual solid removal during ethanol fermentation was unnecessary and 24 h fermentation duration was optimal for ethanol production; (2) ethanol yield of 179.20 g/kg of solid state fermented sweet sorghum bagasse achieved under the optimized process conditions of cellulase loading of 0.04 g/g-glucan, xylanase loading of 0.01 g/g-xylan, liquid to solid ratio of 9:1 and pre-hydrolysis duration for 72 h. © 2014 by the authors.

Du R.,Tsinghua University | Yan J.,Tsinghua University | Feng Q.,Tsinghua University | Li P.,Tsinghua University | And 3 more authors.
PLoS ONE | Year: 2014

The rising demand for bioethanol, the most common alternative to petroleum-derived fuel used worldwide, has encouraged a feedstock shift to non-food crops to reduce the competition for resources between food and energy production. Sweet sorghum has become one of the most promising non-food energy crops because of its high output and strong adaptive ability. However, the means by which sweet sorghum stalks can be cost-effectively utilized for ethanol fermentation in large-scale industrial production and commercialization remains unclear. In this study, we identified a novel Saccharomyces cerevisiae strain, TSH1, from the soil in which sweet sorghum stalks were stored. This strain exhibited excellent ethanol fermentative capacity and ability to withstand stressful solid-state fermentation conditions. Furthermore, we gradually scaled up from a 500-mL flask to a 127-m3 rotary-drum fermenter and eventually constructed a 550-m3 rotarydrum fermentation system to establish an efficient industrial fermentation platform based on TSH1. The batch fermentations were completed in less than 20 hours, with up to 96 tons of crushed sweet sorghum stalks in the 550-m3 fermenter reaching 88% of relative theoretical ethanol yield (RTEY). These results collectively demonstrate that ethanol solid-state fermentation technology can be a highly efficient and low-cost solution for utilizing sweet sorghum, providing a feasible and economical means of developing non-food bioethanol. © 2014 DU et al.

Ding R.,Tsinghua University | Wu Y.,Tsinghua University | Wu Y.,Beijing Engineering Research Center for Biofuels | Chen Y.,Tsinghua University | And 4 more authors.
Catalysis Science and Technology | Year: 2016

Novel Co-doped MoO2/CNTs catalysts were prepared by a wet-impregnation method and employed in catalytic hydrodeoxygenation (HDO) of palmitic acid. The obtained catalysts were systematically characterized using various techniques, namely, XRD, BET surface area, XPS, FT-IR spectroscopy of adsorbed pyridine, Raman, H2-TPD, and H2-TPR. Characterization studies revealed the doping of Co ions into the lattice of MoO2, the interaction between metal species modified the electrical properties of the catalytic active sites, and the formation of new active sites and defects. The catalytic results showed that Co ions could significantly improve catalytic performance, and the best selectivity to hexadecane reached 89.3% at an extremely low temperature of 180°C. The increased presence of Mo2C particles, Lewis acidic sites and oxygen vacancies were all responsible for the noticeable catalytic performance of the Co doped catalyst. The mechanistic insights from this work confirmed the bifunctional role of Co-doped MoO2/CNTs catalysts for HDO of palmitic acid, which was catalyzed either solely by Mo2C or synergistically by Mo2C and MoO2. Insights into the nature of the active site would provide a useful knowledge for rational design of effective Mo-based HDO catalysts and assist future studies on more efficient catalytic conversion systems. © The Royal Society of Chemistry 2016.

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