Beijing Engineering Research Center for Biofuels

Beijing, China

Beijing Engineering Research Center for Biofuels

Beijing, China
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Wu X.,Tsinghua University | Wu X.,Dongfeng Peugeot Citroen Automobile Co. | Liang J.,Tsinghua University | Wu Y.,Tsinghua University | And 4 more authors.
RSC Advances | Year: 2017

In the current study, Dunaliella tertiolecta (D. tertiolecta) and polypropylene (PP) were chosen to investigate the co-liquefaction process of microalgae and plastic. The results show that a maximum synergistic effect was found when the mass ratio of D. tertiolecta to PP was 8 : 2. The addition of PP mainly impacts the composition of the bio-oil products, particularly reducing the acid content. When D. tertiolecta was liquefied individually, the relative content of acid in bio-oil could reach 18.73%, while for D. tertiolecta and PP co-liquefaction in a ratio of 8 : 2, the acid content of bio-oil was lower than the detection limit of GC-MS (lower than 100 ppm). The reaction mechanism for the co-liquefaction process of PP and the main components of microalgae has also been studied. The addition of PP has a significant effect on the transformation pathways of carbohydrates in microalgae, and this also promotes the Maillard reaction between carbohydrates and proteins or their hydrolysates. © The Royal Society of Chemistry.

Shi Y.,Tsinghua University | Xing E.,Sinopec | Wu K.,Tsinghua University | Wang J.,Tsinghua University | And 3 more authors.
Catalysis Science and Technology | Year: 2017

Upgrading of bio-oil is of high necessity and popularity in converting biomass to high-quality hydrocarbons (transportation fuels and petrochemicals) to reduce the overall CO2 emissions of fossil based materials. There are hundreds of different oxygenated compounds identified in bio-oil, resulting in a high oxygen content (30% to 50%). This review focuses on recent progress in the upgrading of bio-oil over metal/zeolite bifunctional catalysts, with model compounds and real bio-oil included. Firstly, typical model compounds and corresponding reaction routes are summarized, based upon the composition of the bio-oil and a basic knowledge of chemical reactions. Secondly, careful analyses are conducted on the deoxygenation mechanisms over different metal active centers and acid-catalyzed reactions, such as isomerization and cracking, over zeolitic acid sites, respectively. Moreover, detailed analyses have focused on the effect of metal loadings on zeolites, the effects of zeolitic porosity and acidity on the metal, and their overall effects on reaction activity, selectivity and stability. Thirdly, the fundamental understanding of the interaction between the metal centers and zeolite acid sites in bifunctional catalysts and their influences on complex reaction networks, including deoxygenation and acid-catalyzed reactions, is analyzed. The metal/acid balance may be the key in improving the catalytic activity and product selectivity in the upgrading of bio-oil, which needs further careful design. Finally, the potential challenges and opportunities for the upgrading of bio-oil over metal/zeolite bifunctional catalysts are outlined. © The Royal Society of Chemistry 2017.

Fang X.,Tsinghua University | Shi Y.,Tsinghua University | Wu K.,Tsinghua University | Liang J.,Tsinghua University | And 3 more authors.
RSC Advances | Year: 2017

The addition of phosphotungstic acid (PTA) to the synthesis mixture of PdCu@FeIII-MOF-5 yields the direct encapsulation of PTA inside the MOF structure (i.e. PTA@PdCu@FeIII-MOF-5) through a facile solvothermal approach. The deoxygenation reaction of palmitic acid has been investigated over PdCu@FeIII-MOF-5 and PTA@PdCu@FeIII-MOF-5 under a hydrogen atmosphere in the supercritical fluid (SCF) of n-hexane. The results showed that palmitic acid can be converted completely at 240 °C on PTA@PdCu@FeIII-MOF-5 with a high selectivity of hexadecane. Owning to the improvement of acidity of the MOF catalyst by the encapsulation of PTA inside the hollow octahedral nanostructures of PdCu@FeIII-MOF-5, the selectivity for hexadecane over the PTA@PdCu@FeIII-MOF-5 catalyst is higher than that over PdCu@FeIII-MOF-5. The excellent performance in the catalytic hydrodeoxygenation (HDO) of palmitic acid is associated with the synergistic effect between yolk-shell PTA@PdCu@FeIII-MOF-5 nanostructures and SCF medium. © 2017 The Royal Society of Chemistry.

Shi Y.,Tsinghua University | Cao Y.,Tsinghua University | Duan Y.,Tsinghua University | Chen H.,Tsinghua University | And 4 more authors.
Green Chemistry | Year: 2016

Bi-functional Mo/ZSM-22 catalysts were designed to upgrade palmitic acid and further to isomerize n-alkanes. Besides the effects on acidity, H+ cations might be beneficial for the distribution of MoOx particles, the higher surface Mo/Si ratio and the greater surface Mo4+ content of bi-functional Mo/ZSM-22 catalysts. In the upgrading of palmitic acid, strong acid sites of catalysts were proven to favor hydrodecarbonylation (HDC), isomerization and cracking. Mo6+ (or MoO3) preferred to support the HDC reaction, whereas Mo4+ (or MoO2) suitably improved the hydrodeoxygenation (HDO) reaction without carbon atom loss. That is, the Mo4+/Mo6+ ratio of Mo/ZSM-22 catalysts significantly influenced HDO/HDC selectivity. More importantly the improvement in HDO rather than HDC with the complete conversion of palmitic acid, could significantly decrease the negative effects of strong acid sites (such as HDC and cracking) to facilitate isomerization of n-alkanes to afford more branched alkanes with a higher iso-alkanes/n-alkanes ratio. © The Royal Society of Chemistry 2016.

Wu K.,Tsinghua University | Liu J.,Tsinghua University | Wu Y.,Tsinghua University | Wu Y.,Beijing Engineering Research Center for Biofuels | And 4 more authors.
Bioresource Technology | Year: 2014

The differences in pyrolysis process of three species of aquatic biomass (microalgae, macroalgae and duckweed) were investigated by thermogravimetric analysis (TGA). Three stages were observed during the pyrolysis process and the main decomposition stage could be divided further into three zones. The pyrolysis characteristics of various biomasses were different at each zone, which could be attributed to the differences in their components. A stepwise procedure based on iso-conversional and master-plots methods was used for the kinetic and mechanism analysis of the main decomposition stage. The calculation results based on the kinetic model was in good agreement with the experimental data of weight loss, and each biomass had an increasing activation energy of 118.35-156.13. kJ/mol, 171.85-186.46. kJ/mol and 258.51-268.71. kJ/mol in zone 1, 2 and 3, respectively. This study compares the pyrolysis behavior of various aquatic biomasses and provides basis for further applications of the biomass thermochemical conversion. © 2014.

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.

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.

Yu M.,Tsinghua University | Li J.,Tsinghua University | Li S.,Tsinghua University | Du R.,Tsinghua University | And 4 more authors.
Applied Energy | Year: 2014

A cost competitive integrated technology to convert solid state fermented sweet sorghum bagasse (SS) into cellulosic ethanol which combined ethanol distillation, NaOH pretreatment and simultaneous saccharification and co-fermentation (SSCF) was presented in this study. After solid-state fermentation, the SS was distilled with 10% (w/w dry material, DM) NaOH to separate sugar-based ethanol and pretreat lignocelluose simultaneously in one step and one distillation stripper, then the NaOH pretreated SS was subsequently converted into cellulosic ethanol by SSCF. Results showed that 69.49% ethanol theoretical yield was achieved under the optimal condition based on this novel integrated process. This integrated technology can significantly reduce the energy consumption and capital cost for cellulosic ethanol production, and ensure cellulosic ethanol produced from SS cost-effectively. © 2013.

Wu K.,Tsinghua University | Wu Y.,Tsinghua University | Wu Y.,Beijing Engineering Research Center for Biofuels | Chen Y.,Tsinghua University | And 3 more authors.
ChemSusChem | Year: 2016

Different biobased chemicals are produced during the conversion of biomass into fuels through various feasible technologies (e.g., hydrolysis, hydrothermal liquefaction, and pyrolysis). The challenge of transforming these biobased chemicals with high hydrophilicity is ascribed to the high water content of the feedstock and the inevitable formation of water. Therefore, aqueous-phase processing is an interesting technology for the heterogeneous catalytic conversion of biobased chemicals. Different reactions, such as dehydration, isomerization, aldol condensation, ketonization, and hydrogenation, are applied for the conversion of sugars, furfural/hydroxymethylfurfural, acids, phenolics, and so on over heterogeneous catalysts. The activity, stability, and reusability of the heterogeneous catalysts in water are summarized, and deactivation processes and several strategies are introduced to improve the stability of heterogeneous catalysts in the aqueous phase. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Wu X.,Tsinghua University | Wu Y.,Tsinghua University | Wu Y.,Beijing Engineering Research Center for Biofuels | Wu K.,Tsinghua University | And 3 more authors.
Bioresource Technology | Year: 2015

In the current work, the co-pyrolysis kinetics of Dunaliella tertiolecta and PP were investigated via TGA, while TG-FTIR and TG-MS were used for the analysis of gas-phase components and volatiles transition. The TGA results show that PP with certain small particle size accelerates the pyrolysis process of the microalgae, while the existence of D. tertiolecta delayed that of PP. This significant interaction achieves maximum when mass ratio of PP and D. tertiolecta is 6:4. The activation energy estimated from FWO kinetic model also supports this interaction. The TG-FTIR and TG-MS results show that a significant decrease of CO2 occurs at PP and D. tertiolecta mass ratio of 6:4, indicating that small molecules (such as radicals) released by PP might react with CO2 produced by D. tertiolecta or carbonyl groups in the microalgae. © 2015 Elsevier Ltd.

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