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Butenolide Derivatives of Biobased Furans: Sustainable Synthetic Dyes.
Get PDFThe dye and pigment manufacturing industry is one of the most polluting in the world. Each year, over one million tons of petrochemical colorants are produced globally, the synthesis of which generates a large amount of waste. Naturally occurring, plant-based dyes, on the other hand, are resource intensive to produce (land, water, energy), and are generally less effective as colorants. Between these two extremes would be synthetic dyes that are fully sourced from biomass-derived intermediates. The present work describes the synthesis of such compounds, containing strong chromophores that lead to bright colors in the yellow to red region of the visible spectrum. The study was originally motivated by an early report of an unidentified halomethylfurfural derivative which resulted from hydrolysis in the presence of barium carbonate, now characterized as a butenolide of 5-(hydroxymethyl)furfural (HMF). The method has been generalized for the synthesis of dyes from other biobased platform molecules, and a mechanism is proposed
Synthesis of higher alcohols by CO hydrogenation over catalysts derived from LaCo 1-x Mn x O 3 perovskites: Effect of the partial substitution of Co by Mn
Get PDFAbstract(#br)LaCo 1- x Mn x O 3 perovskites with different substitutions of Co by Mn were investigated as precursors of catalysts for the CO hydrogenation to produce higher alcohols. Characterization of LaCo 1- x Mn x O 3 perovskites revealed modifications in their structure with the incorporation of Mn into the perovskite lattice affected the structure of the catalysts by reduction prior the reaction. The presence of Mn facilitated the production of alcohols and suppressed the formation of undesirable products, i.e., methane and methanol. Quantitative analysis showed that the catalysts derived from Mn-containing perovskites favored the formation of Co 2 C under the reaction conditions. Thereby the enhanced alcohol selectivity could be explained by the increment of Co 2 C/Co 0 ratio. The results demonstrate that the catalysts originated from LaCo 1- x Mn x O 3 perovskites are stable and effective for the synthesis of alcohols by CO hydrogenation
PE-SERF: A sensitivity-improved experiment to measure JHH in crowded spectra.
Get PDFAiming at facilitating the analysis of molecular structure, the gradient-encoded selective refocusing methods (G-SERF) and a great number of its variants for measuring proton-proton coupling constants have been proposed. However, the sensitivity is an issue in the 2D gradient-encoded experiments, because the signal intensity is determined by the slice thickness of the sample that depends on encoding gradient and the bandwidth of selective pulses which is limited by the smallest chemical shift difference of any two coupled protons. Here, we present a method dubbed PE-SERF (perfect echo selective refocusing) which can determine all JHH values involving a selected proton with improved sensitivity compared to original G-SERF experiment. The modules of perfect echo involving selective pulses and gradient-encoded selective refocusing are combined in the method, so that the unwanted J couplings arising from coupled spin pairs in the same sample slice would be nullified. In this way, instead of single proton, a pair of coupled protons is allowed to share a sample slice, and thus the slice thickness can be increased and the spectral sensitivity can be improved. The performance of the method is demonstrated by experiments on quinine and strychnine
烟草剩余物制备致香物质的研究
Get PDF以云南烟叶、烟秆为原料,以无水乙醇为溶剂,采用水热法制备生物基致香物质。对影响烟叶提取率的液料比、液化温度、液化时间、原料种类4个影响因素进行了研究。分别使用石油醚和二氯甲烷对液化物进行萃取,用气相色谱-质谱联用技术(GC-MS)对萃取成分进行分析。结果表明,反应时间的越长,热解产物中致香总物质含量越低。相同制备工艺条件下,烟叶为原料制备的致香物质总含量要高于烟秆。随着溶剂量的增加,体系中致香物质总含量随之降低。反应制备温度越高致香物质含量随之下降。云南省烟草化学重点实验室开放项目（2017539200340395）云南省科技计划项目（2017FD236
Mn-doped CoSe2 nanosheets as high-efficiency catalysts for the oxygen evolution reaction.
Get PDFIn this work, we introduce for the first time an aqueous solution method followed by a selenization step to prepare Mn-doped CoSe2 nanosheets supported on nickel foam for the oxygen evolution reaction. These findings provide us highly efficient electrocatalysts instead of noble metal catalysts for the oxygen evolution reaction
一种富集高温栅藻Desmodesmus sp. F51的新型生物絮凝剂
Get PDF【背景】海科贝特氏菌(Cobetia marina)可产生大量具有絮凝活性的胞外产物，可视为一种新型的生物絮凝剂。高温栅藻(Desmodesmus sp. F51)是一种具有较高叶黄素含量的微藻，被认为是一种新兴的叶黄素来源，但利用该生物絮凝剂高效富集高温栅藻的相关研究迄今尚未见报道。【目的】以高温栅藻为对象，研究该新型生物絮凝剂的絮凝效率，并对絮凝机理进行初步探讨。【方法】探索在不同生长阶段微藻培养液添加生物絮凝剂、添加量、絮凝时间、pH对絮凝效率的影响，分析生物絮凝剂的功能基团，并测定在不同pH条件下添加生物絮凝剂前后高温栅藻的Zeta电位变化，以及在显微镜下分析藻细胞在添加生物絮凝剂前后的形态。【结果】在高温栅藻生长至稳定期，pH 8.0添加2 mL生物絮凝剂，絮凝15 min絮凝效果最佳，达82.1%。傅里叶红外图谱显示了多糖及酰胺结构的特征吸收峰，由此推测生物絮凝剂主要是多糖的混合物，含有少量蛋白质。根据Bradford法测定絮凝剂中蛋白含量约为0.4%(质量比)，通过苯酚-硫酸法测定总糖质量分数约为34.5%(质量比)，与FTIR谱分析结果基本相符。生物絮凝剂在pH 4.0～11.0保持60%以上的絮凝效率，说明无论是酸性或是碱性条件下絮凝效率都较高，结合Zeta电位的分析表明，推测生物絮凝剂对高温栅藻的絮凝机理中占主导地位的可能是吸附架桥作用。【结论】该研究对微藻生物絮凝具有重要的理论和实践意义。厦门市科技计划项目(3502Z20173018)福建省自然科学基金(2017J01077)国家自然科学基金项目 (31871779
采用茂金属催化剂制备乙烯-1-辛烯共聚物及其性能研究
Get PDF采用自制单茂金属催化剂MXC,经Al（i-Bu）3和[Ph3C]+[B（C6F5）4]-活化后对乙烯和1-辛烯进行了催化共聚,利用核磁共振碳谱(13C-NMR)、凝胶渗透色谱（GPC）、差示扫描量热法（DSC）考察了聚合条件对催化剂催化性能的影响,对比了共聚物样品以及进口韩国SK公司的聚烯烃弹性体（POE）产品。结果表明:共聚物样品与SK公司的POE产品在13C-NMR中有相似的吸收峰,组成及聚集态结构相近;随催化剂Al/Ti比（摩尔比,下同）减小,催化活性增加,共聚物的重均相对分子质量（■w）先减小后增大;聚合温度从90℃升高至130℃,催化活性降低,共聚物的相对分子质量减小,相对分子质量分布指数（PDI）变宽;当Al/Ti比为300时,共聚物■w由24.36×104降至9.87×104;当Al/Ti比为150,聚合温度为110℃时,催化活性达到11.77×106g/（mol·h）,共聚物■w,PDI,熔融温度、结晶度依次为10.05×104, 3.14, 76.95℃, 2.27%,1-辛烯插入率达到13.2%
Well-dispersed Pd–Sn nanocatalyst anchored on TiO 2 nanosheets with enhanced activity and durability for ethanol electarooxidation
Get PDFAbstract(#br)Novel Pd 1 -Sn x /TiO 2 nanosheets catalyst with higher activity and durability for ethanol oxidation (EOR) was obtained by NaBH 4 co-reduction method in direct ethanol fuel cells (DEFCs). The electrochemical performance tested under alkaline conditions illustrates that the prepared Pd 1 –Sn 0.6 /TiO 2 NSs catalyst presents outstanding activity (3381 mA mg Pd − 1 ) and excellent CO anti-poisoning ability for EOR. Meanwhile, the residual current density of Pd 1 –Sn 0.6 /TiO 2 NSs nanocatalyst (1207 mA mg Pd − 1 ) is 8.5 times of the Pd/C (JM) catalyst (142 mA mg Pd − 1 ) after the durability test of 5000 s for EOR. Additionally, the Pd 1 -Sn x /TiO 2 nanosheets show prominent electrocatalytic activity in EOR comparison with Pd/TiO 2 nanosheets and Pd–Sn nanocatalysts. Thus, Pd and Sn doped in TiO 2 nanosheets not only display excellent electrocatalytic, but also reduce the cost of Pd, which have some reference value for DEFCs
Ultrathin MOF nanosheet assembled highly oriented microporous membrane as an interlayer for lithium-sulfur batteries
Get PDFAbstract(#br)Lithium sulfur (Li-S) batteries are attracting increasing attentions as promising next-generation rechargeable batteries. However, the rapid capacity fading of sulfur cathodes caused by the shuttling of polysulfide intermediates between the cathodes and anodes restricts the application of Li-S batteries. In this work, a facile wet-chemistry method is developed for the direct synthesis of few-molecular-layer thin metal-organic framework (MOF) nanosheets without using surfactant. By assembling these ultrathin MOF nanosheets with a facile vacuum filtration method, a highly oriented and flexible MOF membrane with favorable mechanical properties is achieved for the first time. The excellent features make the as-prepared MOF nanosheets ideal to fabricate lightweight interlayer modified separators for suppressing the polysulfide shuttling of Li-S batteries. When using the MOF membrane modified separator, the Li-S batteries made from commercial carbon materials exhibits the significantly enhanced cycling stabilities. This work brings new opportunities for the synthesis and application of MOF materials
