Zheng Shen

Tongji University, Shanghai, Shanghai Shi, China

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Publications (14)24.43 Total impact

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    ABSTRACT: Extrusion pretreatment was applied to enhance fermentative methane production from rice straw. The extrusion-pretreated rice straw (EPRS) showed significant particle size reduction, physical properties improvement and volume expansion, as compared to the milling-pretreatment rice straw (MPRS) and unpretreated rice straw (UPRS). The anaerobic digestion of EPRS, MPRS and UPRS with different inoculum-to-substrate ratios (ISRs) and solid loading rates (SLRs) was investigated. The highest specific methane production (SMP) of the EPRS was 227.3 L/g VS with an ISR of 0.4 and SLR of 50 kg/m3, which was 32.5% and 72.2% greater than that of the MPRS and UPRS at the corresponding ISR and SLR, respectively. Furthermore, the volumetric methane production (VMP) increased with increasing SLR. The highest VMP (17.0 m3/m3) of the EPRS was obtained with an SLR of 90 kg/m3, which was 1.5 times that of the MPRS. In addition, the EPRS had significantly shorter technical digestion time and higher cellulose and hemicellulose degradation efficiencies, which was due to the smaller particle size and larger specific surface area of the EPRS, thus contributing to the enhancement of methane production. The SEM analyses further demonstrated that the cellulose of the rice straw was devillicated after extrusion pretreatment, which was in agreement with the higher cellulose and hemicellulose degradation efficiencies of the EPRS.
    Applied Energy. 01/2014; 122:34–41.
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    ABSTRACT: BACKGROUND: Glycerine, a main by-product of the biodiesel manufacturing process, has potential to be an important biorefinery feedstock with the rapid increase in biodiesel production all over the world. Hydrothermal experiments with glycerine were carried out at 250 °C using H2O2 as an oxidant. RESULTS: Glycerine was converted into formic acid with a yield of 31.0% based on the starting mass of carbon in glycerine. A possible oxidation pathway for the formation of formic acid from glycerine is proposed. In the proposed pathway, glycerine may first be oxidised and then decomposed into formic acid and oxalic acid. Oxalic acid was indirectly attributed to the increase of formic acid production from glycerine, but it instead acts as a retardant to prevent further oxidation of formic acid. However, when an alkali was added to the experimental conditions, the yield of formic acid was not greatly improved, reaching only 34.7%. CONCLUSION: The present work should help to facilitate further studies to develop a new green process for the production of formic acid from renewable biomass. © 2012 Society of Chemical Industry
    Journal of Chemical Technology & Biotechnology 05/2013; 88(5). · 2.50 Impact Factor
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    ABSTRACT: To discover the reaction mechanism for the production of hydrogen and lactic acid from glycerol under alkaline hydrothermal conditions, we identified the different intermediates involved during reactions by investigating the solvent isotope effect with 1H-NMR, 2H-NMR, LC-MS and Gas-MS analyses, and then proposed and proved a potential reaction mechanism.
    Green Chemistry 11/2012; 14(12):3285-3288. · 6.83 Impact Factor
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    ABSTRACT: This study examined the impacts of bacteria on the algal biomass, lipid content and efficiency of wastewater treatment during the heterotrophic cultivation of Chlorella pyrenoidosa. Our results showed that soybean-processing wastewater can enhance the accumulation of lipids in algal cells and thus raise the lipid yield in the pure culture. The bacteria coexisting with algae improved the degradation of total nitrogen (TN), total phosphorus (TP), glucose and chemical oxygen demand (COD). Although the biomass productivity of algae was not significantly affected, the total algal lipid content and lipid production rate were slightly reduced when bacteria coexisted with algae. The difference in the compositions of the medium is presumed to be the main contributing factor for the variation in total lipid content in presence and absence of bacteria. The TN, TP, and COD decreased during the assimilatory process undertaken by C. pyrenoidosa, and the removal efficiency of TN by bacteria depended on the type of nitrogen species in the medium. Additionally, the apparent interaction between the bacterial and algal cultures varied with the changes in experimental conditions. Algae could compete with bacteria for the carbon and energy sources, and inhibit the growth of the bacteria in the presence of high organic matter concentration in the medium.
    Water Research 07/2012; 46(17):5509-16. · 4.66 Impact Factor
  • Zheng Shen, Yalei Zhang, Fangming Jin
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    ABSTRACT: A hydrothermal method for the hydrogen-transfer reduction of CO2 or NaHCO3 is presented. This process uses glycerine as a reducing agent, which is ultimately converted to lactate, and can convert NaHCO3 into formate in about a 90% yield with respect to the initial amount of glycerine.
    RSC Advances 01/2012; 2(3):797-801. · 2.56 Impact Factor
  • Zheng Shen, Yalei Zhang, Fangming Jin
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    ABSTRACT: In high-temperature water (HTW), NaHCO3 is reduced into formate using isopropanol as a reducing agent. Based on the initial reducing agent isopropanol, a relatively high yield of formate was obtained of about 70%. Another curious aspect in HTW is that water molecules may act as a catalyst for hydrogen-transfer reduction of NaHCO3 with isopropanol, taking the place of the metal catalysts used in heterogeneous and homogeneous catalytichydrogenation of CO2. The present work should help facilitate studies for developing new green processes for the transformation of CO2 using organic hydrogen sources as the reducing agents.
    Green Chemistry 04/2011; 13(4):820-823. · 6.83 Impact Factor
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    ABSTRACT: Microalgae for carbon dioxide mitigation was converted into acetic acid by hydrothermal reaction with H202 oxidant. Results showed that the greatest yield acetic acid was 14.9% based on a carbon base at 300 DC for 80 s with 100% H202 supply. This result should be helpful to facilitate studies for developing a new green and sustainable process in order to produce acetic acid from micro algae, which are the fastest growing sunlight-driven cell factories. acetic acid n (\'fJOnwm)
    01/2011;
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    ABSTRACT: Microalgae for carbon dioxide mitigation was applied to the production of acetic acid under hydrothermal conditions with H2O2 oxidant. Results showed that acetic acid was obtained with a good yield of 14.9% based on a carbon base at 300 °C for 80 s with 100% H2O2 supply. This result should be helpful to facilitate studies for developing a new green and sustainable process in order to produce acetic acid from microalgae, which are the fastest growing sunlight-driven cell factories. These results show that it is possible to develop a process for conversion of microalgae biomass into acetic acid.
    Applied Energy. 01/2011; 88(10):3444-3447.
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    ABSTRACT: The hydrothermal experiments with ketones and formic acid showed that the hydrogen transfer reduction of ketones can be conducted with formic acid as a hydride donor in the presence of NaOH at 300° C. The yield of alcohols was considerably higher at a much lower ratio of hydrogen source to ketones than the traditional Meerwein-Ponndorf-Verley reduction, reaching 60% for isopropanol from acetone and 70% for lactic acid from pyruvic acid. Water molecules as a catalyst may directly participate in the transition state by making a hydrogen-bond ring network with the substrate molecules.
    11/2010;
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    ABSTRACT: In hydrothermal reactions at 260−300 °C, ketones can be reduced into corresponding alcohols by hydrogen transferring from another alcohols or formic acid without a metal catalyst. When using formic acid as a hydrogen donor, the yield of alcohols at respective better conditions was considerably high at a much lower ratio of hydrogen source to ketones compared to traditional Meerwein−Poundrof−Verley (MPV) reduction, reaching 60% for isopropanol from acetone and 70% for lactic acid from pyruvic acid. The proposed possible mechanism for the hydrogen transfer reduction of ketones in high-temperature water (HTW) is similar to the pathway elucidated in the traditional MPV reduction via a transition state. Rather than metal-alkoxides catalysts in MPV reduction, water molecules in HTW as a catalyst may directly participate in the transition state by making a hydrogen-bond ring network with three molecules, that is, ketone, formic acid, and water.
    Industrial & Engineering Chemistry Research. 06/2010; 49(13).
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    ABSTRACT: The production of formic and acetic acids (or salts) by hydrothermal oxidation of syringol, a model compound for lignin, was investigated using a batch reactor. Results show that the highest yields of formic and acetic acids were, respectively, 59.6% and 11.3% at the reaction condition of 0.5 mol/L NaOH, 120% H2O2 supply and 280 °C. These results will inform studies aiming to develop more environmental friendly lignin conversion processes by obtaining products beyond a CO2 end product. Key wordsLignin-Syringol-Formic acid-Acetic acid-Hydrothermal process CLC numberX24-O62
    Journal of Zhejiang University - Science A: Applied Physics & Engineering 01/2010; 11(8):613-618. · 0.53 Impact Factor
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    ABSTRACT: Hydrothermal treatment of glycerin was carried out at 300 °C by using eight alkaline catalysts, including hydroxides of alkali metals, alkaline-earth metals, and aluminum. All alkaline catalysts promoted the formation of lactic acid or lactate salts from glycerin, except for Al(OH)3. The alkali-metal hydroxides were more effective than alkaline-earth-metal hydroxides on the catalysis of hydrothermal reactions. On the hydrothermal conversion of glycerin into lactic acid, the catalytic effectiveness followed the sequence of KOH > NaOH > LiOH for alkali-metal hydroxides, and Ba(OH)2 > Sr(OH)2 > Ca(OH)2 > Mg(OH)2 for alkaline-earth hydroxides. An excellent lactic acid yield of 90% was attained on hydrothermal conversion of glycerin at 300 °C with KOH or NaOH as a catalyst. KOH was superior to NaOH as a catalyst since it worked at a lower concentration or within a shorter reaction time to obtain the same lactic acid yield. The hydrothermal conversion of glycerin depended not only on the hydroxide ion concentration but also on the metal ions of catalysts.
    Industrial & Engineering Chemistry Research - IND ENG CHEM RES. 09/2009;
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    ABSTRACT: The hydrothermal experiments with ketones and formic acid showed that the hydrogen transfer reduction of ketones can be conducted using formic acid as a hydride donor in the presence of NaOH at 300 °C. The yield of alcohols was considerably higher at a much lower ratio of hydrogen source to ketones than the traditional Meerwein-Ponndorf-Verley (MPV) reduction, reaching 60% for isopropanol from acetone and 70% for lactic acid from pyruvic acid. Water molecules may act as a catalyst in the hydrogen transfer reduction of ketones under hydrothermal conditions.
    Journal of Zhejiang University - Science A: Applied Physics & Engineering 01/2009; 10(11):1631-1635. · 0.53 Impact Factor
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    ABSTRACT: Hydrothermal treatment of glycerin was carried out at 300degC by using eight base catalysts, including hydroxides of alkali metals, alkaline-earth metals and aluminum. All selected catalysts promoted the conversion of glycerin into lactic acid, except for Al(OH)3. The alkali-metal hydroxides were found to be more effective than alkaline-earth-metal hydroxides on hydrothermal conversion of glycerin. In the case of NaOH or KOH, a lactic acid yield of approximate 90% can be approached. Moreover, KOH was superior to NaOH on promoting the hydrothermal conversion of glycerin. Ba(OH)2 and Sr(OH)2 was found to convert glycerin further into formic and acetic acids. A decomposition mechanism of lactic acid with Ba(OH)2 was proposed.
    01/2009;