Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences
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No full text化石燃料消耗量的逐渐增加导致全球能源危机，同时，化石燃料燃烧后排放的温室气体引发的温室效应已经成为人类历史上环境问题的最大考验。因此，探索一种可替代非再生的化石燃料的能源就显得尤为重要。使用生物质燃料来代替传统能源燃料已经引起了研究者的广泛关注。其中，生物质通过加氢脱氧反应制备与传统石化能源相似组分的链烷烃是目前的研究热点。现阶段，加氢脱氧催化剂的载体有三种：负载型贵金属催化剂、负载型硫化态过渡金属催化剂和负载型还原态过渡金属催化剂。负载型硫化态催化剂中的硫会污染产物，贵金属催化剂价格较为昂贵，因此本课题选用负载型过渡金属催化剂作为研究对象。目前，相比于酸性或中性载体，如H-ZSM-5、SAPO-34，γ-Al2O3等，碱性载体很少受到人们的关注。考虑到碱性载体可以减少原料的裂解反应，增加液相产物的收率，而且抑制积碳。因此，本研究选用碱性复合氧化物作为催化剂载体。
本论文制备不同碱性复合氧化物作为催化剂载体MO-Al2O3（ M = Mg, Ca, Ni, Cu, Zn）。然后采用等体积浸渍的方法制备Ni基催化剂Ni/ MO-Al2O3。以油酸作为模型化合物，在100 ml的高压反应釜中反应来测试不同催化剂的催化油酸加氢脱氧反应制备烷烃的催化性能。结果表明碱性催化剂载体对油酸加氢脱氧制备烷烃的反应有很好的促进作用。在反应温度为280 °C、H2压力为3.0 MPa下，碱性适中的Ni/ZnO-Al2O3 催化剂呈现出最佳的催化反应性能，可使油酸的转化率高达100 %，烷烃（C17+C18）的产率高达99%。相比之下，催化剂（Ni/CaO-Al2O3 和Ni/MgO-Al2O3）在反应过程中，由于催化剂载体碱性较强，易与反应物油酸或加氢后的硬脂酸生成脂肪酸盐，导致催化活性较低。另外，增加活性组分Ni的负载量、提高反应温度和H2压力均有助于烷烃的生成，且催化剂的活性对反应温度的变化更敏感。作为该反应的主要产物，C17主要来源于硬脂酸十八酯的氢解和随后生成的十八醛的脱羰反应，该反应为油酸加氢脱氧反应的主要路径。由不同中间产物的反应速率计算结果可知硬脂酸十八酯的氢解反应为整个反应的控速步骤。催化剂经过三次重复利用，仍然保持较高的催化活性，说明其具有较高的催化稳定性。
此外，催化剂载体中的Zn与Al的不同比例对催化剂的催化剂性能有着很大的影响。首先，制备了一系列不同锌铝比的催化剂载体，并通过等体积浸渍法制备相应催化剂。以油酸作为模型化合物，十氢萘作为溶剂，在100 ml的高压反应釜中反应来测试不同催化剂的油酸加氢脱氧反应制备烷烃的催化性能。结果发现具有适中碱性的催化剂Ni/ZnO-Al2O3（Zn/Al =2）具有最佳的催化活性。在反应温度为280 °C、H2压力为2.5 MPa条件下液相产物中烷烃的收率（C17+C18）高达95.8%。随着锌铝比的增加，载体的比表面积减小，其阻碍活性组分镍颗粒的分散。较低的分散度使得镍颗粒的尺寸较大，以及其内部的NiO无法被还原。油酸加氢脱氧反应的转化率及烷烃的选择性与暴露在催化剂表面的单质镍颗粒有密不可分的关系。Progressive depletion of petroleum-based fuels has led to the global energy crisis. The greenhouse gas emission introduced by burning fossil fuels has made the global warming become one of the biggest environmental challenges in human history. Therefore, it is necessary to develop an alternative fuel source that can replace non-renewable fossil fuels. The use of biomass-derived fuels in place of conventional fuels is an emerging field of interest. Hydrodeoxygenation, which converts biomass to hydrocarbon fuels that have all the qualities of conventional fossil fuels, is one of the most interesting and promising techniques in this field. The commonly used hydrodeoxygenation catalysts are supported noble and sulfide or reduced metal catalysts. However, sulfide catalysts would contaminated products due to the formation of sulfur and noble catalysts are not favorable because of their high cost. Therefore, our study devoted to developing non-sulfided transition metal catalysts. Basic support can reduce the cracking of feedstock and increase the yield of liquid products. Moreover, they are more favorable to absorb acidic fatty acids, which may improve triglycerides deoxygenation.
From this viewpoint, a series of Ni-based catalysts supported on basic composite oxides (MO-Al2O3, M = Mg, Ca, Ni, Cu, Zn) were prepared for the catalytic deoxygenation of oleic acid in the presence of H2. Oleic acid was selected as the model reactant for activity tests. Their catalytic activity for the hydrodeoxygenation (HDO) were studied in an autoclave reactor using decalin as solvent. The results indicated that t Ni supported on ZnO-Al2O3 composite exhibited the highest conversion of oleic acid (100%) and selectivity to n-alkanes (99%). A suitable amount of basicity on the support is favorable for oleic acid deoxygenation. Additionally, increasing Ni loading amount and reaction temperature or decreasing H2 pressure were beneficial for the formation of alkanes, especially n-heptadecane. The reaction temperature was more important than H2 pressure in the catalytic deoxygenation of oleic acid. As the predominant product, n-heptadecane was mainly derived from stearyl stearate hydrogenolysis and sequential octadecanal decarbonylation, which is the major route in the whole reaction pathway. The reaction rates of different intermediates confirm that the hydrogenlysis of stearyl stearate is the rate-determining step for the overall reaction of oleic acid. After reuse for three times, the catalyst still maintained a relatively high yield of alkanes (> 90%), showing a high activity stability.
Furthermore, we prepared Ni supported on ZnO-Al2O3 with different Zn/Al atomic ratio by an incipient wetness impregnation method and compared their catalytic performance in HDO of oleic acid to diesel like fuel. The maxim diesel-like alkane (C17+C18) yield of 95.8 % was observed over 10wt %Ni/Zn2.0Al under mild reaction condition, showing its promising catalytic application in this reaction. The increase of Zn/Al ratio can remarkably decrease the specific surface area and weaken the interaction between Ni species and the supports, thereby hindering the dispersion of Ni species. Lower dispersion degree further led to the formation of Ni species particles with larger size, which prevented the Ni species inside of the particles from reducing even if the weak interaction was favorable to the reduction of Ni species. Conversion and deoxygenation of the reactants strongly depended on the hydrogenation performance of the catalysts which was controlled by the proportion of exposed metallic Ni atoms
Novel wide band gap polymers based on dithienobenzoxadiazole for polymer solar cells with high open circuit voltages over 1 V
No full textA new monomer dithieno-[3',2': 3,4; 2 '',3 '': 5,6]benzo[1,2-c]xadiazole (fDTBO) is first used as an electron-deficient acceptor to build D-A copolymers in a photovoltaic field. Two polymers PBDTT-fDTBO and PBDTO-fDTBO consist of fDTBO with thienyl-substituted-benzodithiophene (BDTT) or alkoxy-substituted benzodithiophene (BDTO). Both polymers show a deep HOMO around -5.5 eV with a wide band gap of over 1.9 eV. The polymer solar cells (PSCs) based on two polymers both show over 1 V high open circuit voltage (V-oc) independent of polymer/PCBM ratios and solvent additives content in the PSCs active layer. The power conversion efficiency (PCE) based on PBDTT-fDTBO devices is 4.5% for single junction PSCs, and these polymers can be applied in tandem PSCs due to their wide band gap (up to 1.99 eV). This work demonstrates that the fDTBO unit is a promising building block to design wide band gap photovoltaic polymers with high V-oc
The metabolism and biotechnological application of betaine in microorganism
No full textGlycine betaine (betaine) is widely distributed in nature and can be found in many microorganisms, including bacteria, archaea, and fungi. Due to its particular functions, many microorganisms utilize betaine as a functional chemical and have evolved different metabolic pathways for the biosynthesis and catabolism of betaine. As in animals and plants, the principle role of betaine is to protect microbial cells against drought, osmotic stress, and temperature stress. In addition, the role of betaine in methyl group metabolism has been observed in a variety of microorganisms. Recent studies have shown that betaine supplementation can improve the performance of microbial strains used for the fermentation of lactate, ethanol, lysine, pyruvate, and vitamin B-12, during which betaine can act as stress protectant or methyl donor for the biosynthesis of structurally complex compounds. In this review, we summarize the transport, synthesis, catabolism, and functions of betaine in microorganisms and discuss potential engineering strategies that employ betaine as a methyl donor for the biosynthesis of complex secondary metabolites such as a variety of vitamins, coenzymes, and antibiotics. In conclusion, the biocompatibility, C/N ratio, abundance, and comprehensive metabolic information of betaine collectively indicate that this molecule has great potential for broad applications in microbial biotechnology
Microbiota-based Signature of Gingivitis Treatments: A Randomized Study
No full textPlaque-induced gingivitis can be alleviated by various treatment regimens. To probe the impacts of various anti-gingivitis treatments on plaque microflora, here a double blinded, randomized controlled trial of 91 adults with moderate gingivitis was designed with two anti-gingivitis regimens: the brush-alone treatment and the brush-plus-rinse treatment. In the later group, more reduction in both Plaque Index (TMQHI) and Gingival Index (mean MGI) at Day 3, Day 11 and Day 27 was evident, and more dramatic changes were found between baseline and other time points for both supragingival plaque microbiota structure and salivary metabonomic profiles. A comparison of plaque microbiota changes was also performed between these two treatments and a third dataset where 50 subjects received regimen of dental scaling. Only Actinobaculum, TM7 and Leptotrichia were consistently reduced by all the three treatments, whereas the different microbial signatures of the three treatments during gingivitis relieve indicate distinct mechanisms of action. Our study suggests that microbiota based signatures can serve as a valuable approach for understanding and potentially comparing the modes of action for clinical treatments and oral-care products in the future
Structure of 2D Graphdiyne and Its Application in Energy Fields
No full textThis paper focuses on application of graphdiyne (GDY) in both energy storage and conversion fields, including the most recent theoretical and experimental progress. The unique three-dimensional pore structure formed by stacking of the GDY layer, make it possess the natural advantage which can be applied to lithium storage and hydrogen storage. Because of its lithium storage ability, GDY can be used in energy storage devices, such as lithium ion batteries and lithium ion capacitors. While with the hydrogen storage property, GDY can be used as a hydrogen storage material in fuel cells. By doping method, the performance of GDY for lithium and hydrogen storage can be further improved. Owing to acetylene units composed of sp hybridized carbon atoms and benzene rings composed of sp(2) hybridized carbon atoms, GDY possesses multiple conjugated electronic structures. Thus, its band gap can be regulated through many ways accompanied with existence of Dirac cones. This property means that GDY can not only be used as a high-activity non-metal catalyst in place of noble metal catalysts in photocatalysis, but it also plays a promotional role in the hole transport layer and electron transport layer of solar cells. All of the reported results including theoretical and experimental data reviewed here, show the great potential of GDY in energy field applications
(E)-1,2-Di(thiophen-2-yl)ethene based high mobility polymer for efficient photovoltaic devices without any post treatment
No full textIn order to investigate the effect of an (E)-1,2-di(thiophen-2-yl)ethene (TVT) unit on the hole mobility and photovoltaic properties of dithienyl-difluorobenzothiadiazole (DTBT) based polymers, two conjugated polymers PDT-DTBT-DT (thiophene backboned) and PTVT-DTBT-DT (TVT backboned) were synthesized. Compared to PDT-DTBT-DT, the backbone conformation of PTVT-DTBT-DT could be well modulated by the TVT unit, leading to an extended conjugation length and strengthened intermolecular interaction. Interestingly, it's found that the ultraviolet-visible (UV-vis) absorption peaks of the PTVT-DTBT-DT film was blue-shifted compared to that of the solution. The organic field-effect transistor (OFETs) characterization showed that PTVT-DTBT-DT possessed a high hole mobility of 0.12 cm(2) V-1 s(-1), which was higher than that of the counterpart PDT-DTBT-DT (0.04 cm(2) V-1 s(-1)). Through simplified device optimization without any additives and annealing treatment, a power conversion efficiency (PCE) of 7.86% was achieved for PTVT-DTBT-DT with a short-circuit current density (Jsc) of 16.33 mA cm(-2) and a fill factor (FF) of 68.92%, which is higher the PCE of 7.29% of PDT-DTBT-DT with a Jsc of 15.60 mA cm(-2) and a FF of 66.62%. The PCE of 7.86% is among the highest PCEs reported for devices fabricated without any additives and thermal annealing treatment. The results revealed that PTVT-DTBT-DT as an ideal conjugated polymer could provide a greater possibility for the commercial application of PSCs, especially in terms of low cost and manufacturing convenience
Characterization and ciprofloxacin adsorption properties of activated carbons prepared from biomass wastes by H3PO4 activation
No full textAs biomass wastes, Arundo donax Linn and pomelo peel were used as precursors for activated carbons (ALAC and PPAC) preparation by phosphoric acid activation. The pore structure and surface acidic functional groups of both carbons were characterized by nitrogen adsorption/desorption experiment, NH3-temperature-programmed desorption (NH3-TPD) and Fourier transform infrared spectroscopy (FTIR). A batch of experiments was carried out to investigate the adsorption performances of ciprofloxacin under different conditions. Results showed that PPAC exhibited larger surface area (1252 m(2)/g) and larger portion of mesoporous, while ALAC was typical of microporous materials. Results from NH3-TPD suggested that ALAC was characteristic of more acidic functional group than PPAC. The maximum monolayer adsorption capability was 244 mg/g for ALAC and 400 mg/L for PPAC. Kinetics studies showed intra-particle diffusion was not the unique rate-controlling step. Boundary layer resistance existed between adsorbent and adsorbate. (C) 2016 Elsevier Ltd. All rights reserved
Preparation and characterization of thermally stable cellulose nanocrystals via a sustainable approach of FeCl3-catalyzed formic acid hydrolysis
No full textCellulose nanocrystals (CNCs) can be used as building blocks for the production of many renewable and sustainable nanomaterials. In this work, CNCs were produced from bleached eucalyptus kraft pulp with a high yield over 75 % via FeCl3-catalyzed formic acid (FA) hydrolysis process. It was found that the particle size of resultant CNC products (F-CNC) decreased with the increase of FeCl3 dosage in FA hydrolysis, and a maximum crystallinity index of about 75 % could be achieved when the dose of FeCl3 was 0.015 M (i.e. about 7 % based on the weight of starting material). Thermogravimetric analyses revealed that F-CNC exhibited a much higher thermal stability (the decomposition temperature was over 260 A degrees C) than S-CNC prepared by typical sulfuric acid hydrolysis. In the FeCl3-catalyzed FA hydrolysis process, FA could be easily recovered and reused, and FeCl3 could be transferred to Fe(OH)(3) as a high value-added product. Thus, the FeCl3-catalyzed FA hydrolysis process could be sustainable and economically feasible. In addition, F-CNC could be well dispersed in DMSO and its dispersibility in water could be improved by a cationic surface modification
Downregulation of MTHFR and COMT in Switchgrass Decreases Lignin Content and Induces Lesion-mimic Cell Death
No full textNiCo nanoalloy encapsulated in graphene layers for improving hydrogen storage properties of LiAlH4
No full textNiCo nanoalloy (4-6 nm) encapsulated in grapheme layers (NiCo@G) has been prepared by thermolysis of a 3D bimetallic complex CoCo[Ni(EDTA)](2)center dot 4H(2)O and successfully employed as a catalyst to improve the dehydrogenation performances of LiAlH4 by solid ball-milling. NiCo@G presents a superior catalytic effect on the dehydrogenation of LiAlH4. For LiAlH4 doped with 1 wt% NiCo@G (LiAlH4-1 wt% NiCo@G), the onset dehydrogenation temperature of LiAlH4 is as low as 43 degrees C, which is 109 degrees C lower than that of pristine LiAlH4. 7.3 wt% of hydrogen can be released from LiAlH4-1 wt% NiCo@G at 150 degrees C within 60 min. The activation energies of LiAlH4 dehydrogenation are extremely reduced by 1 wt% NiCo@G doping