I型和II型结构气体水合物的记忆效应

利用水合物二次生成实验装置, 采用“定容法”对I型(甲烷、二氧化碳)和II型(丙烷)结构气体水合物的二次生成进行了实验, 研究了不同结构水合物(I型、II型)彼此间的记忆效应, 发现水合物生成过程存在明显的诱导期, I型结构水合物间在二次生成过程中存在着记忆效应. I型与II型结构水合物之间在相互二次生成过程中存在着显著的记忆效应.     

Fe2O3‐N‐doped Honeycomb‐like Porous Carbon Derived from Nature Silk Sericin as Electrocatalysts for Oxygen Evolution Reaction

A facile method is reported to form a honeycomb‐like porous nanomaterial by intercalation of iron nitrate using nature silk sericin (SS) as nitrogen and carbon source. A series of Fe₂O₃ nanoparticles anchored on Fe₂O₃‐N‐doped graphite carbon electrocatalysts (SS‐Fe) were synthesized, exhibits well‐defined pore structure and excellent oxygen evolution reaction (OER) catalytic activities. Among these materials, SS‐Fe‐0.5 shows the best performance, the overpotential of SS‐Fe‐0.5 at 10 mA · cm^–2 is 440 mV (vs. RHE) and the Tafel slope is only 68 mV · dec^–1. The results indicate that it is promising to the preparation of carbon catalyst materials using natural, renewable and abundant resources for electrocatalysis.     

Analysis of PCB by on-line coupled HPLC-HRGC

Summary On-line coupled HPLC-GC has been used for the fractionation and analysis of polychlorobiphenyls (PCB) according to their planarity. HPLC elution with porous graphitic carbon (PGC) as stationary phase, enables fractionation of PCB into classes according to the amount ofortho-substitution, which is related to congener toxicity. This is a preliminary step before GC analysis, which enables complete separation of PCB congeners according to vapour pressure. Conditions for HPLC-HRGC coupling were optimised, in particular the appropriate proper HPLC solvent was selected, because it determines eluent strength and selectivity and the transfer conditions. Different solvent were studied—n-hexane, dichloromethane, benzene, toluene, and their mixtures. Samples containing PCB standards and the commercial mixtures Aroclor 1242 and 1254 were analysed. Dichloromethane-n-hexane, 1:1, was selected as mobile phase for separation of poly-ortho from mono-ortho PCB; benzene-dichloromethane 30:70 resulted in the best separation of the most retained non-ortho-substituted PCB. Under these conditions the co-solvent trapping procedure, performed by adding 4% ethylbenzene as co-solvent, was used as transfer technique to overcome the drawback of losses of volatile congeners. Appropriate analysis conditions were successfully used to fractionate the technical PCB formulations Aroclor 1242 and 1254.     

铁脂质体/水分配系数测定及影响因素考察

基于PAF-301分子模型通过Li 掺杂或B取代等模式设计了几种新型多孔芳香骨架(PAFs)材料, 采用量子力学和分子力学方法对新材料的储氢性能进行研究. 由量子力学计算得到了不同分子片段与H₂之间的结合能, 并结合DDEC方法计算了各分子片段的原子电荷分布. 利用巨正则蒙特卡洛(GCMC)模拟方法计算了77和298 K下H₂在不同PAFs材料中的吸附平衡性质. 结果表明, H₂直接与苯环的结合能较低, 但掺杂Li 原子能够提高H₂与六元环的结合能, 同时Li 原子体现出较高的正电性质, B原子取代苯环中的两个C原子后, 使得原有C原子电负性增强; 77 K下PAF-301Li 具有最高的储氢性能, 而PAF-C₄B₂H₄-Li₂-Si 和PAF-C₄B₂H₄-Li₂-Ge体现出较好的常温储氢性能, 各种材料的常温储氢性能远低于其低温储氢性能. 通过77 K下H₂在PAFs材料中的等位能面分布和吸附平衡质心密度分布对H₂在PAFs 材料中的优先吸附位置进行分析, 发现在PAF-301 和PAF-301Li 骨架中, 由于中心能量较低的等位能区域范围较宽, H₂在其中存在四个明显的吸附高密度分布区域, 而其它三种PAFs晶胞中心能量较低的等位能区域范围较窄, 使得H₂在其中只存在两个明显的吸附高密度分布区域.     

Rapid analysis of triterpenic acids by liquid chromatography using porous graphitic carbon and evaporative light scattering detection

An original system which uses Porous Graphitic Carbon as support and a mixture of organic solvents as mobile phase is proposed for the analysis of triterpenic acids by liquid chromatography. The separation of betulinic acid, ursolic acid, oleanolic acid, and 18alpha- and 18beta-glycyrrhetinic acids was carried out within a short time and monitored by evaporative light scattering detection as universal detection method. Molecular modelling studies show that the main contribution to the selectivity comes from the electrostatic interaction characterised by the dipole moment of the products.     

多孔炭材料在纤维素催化转化中的应用

生物质作为自然界唯一可再生的有机碳资源,其利用受到了越来越多的关注。特别是随着能源和环境危机的日益加重,将生物质中非可食用部分催化转化为燃料及具有高附加值的化学品被认为是高效、环保、原子经济的绿色过程。同时,多孔炭材料具有丰富的孔道结构、优异的水热稳定性和大比表面积,是生物质催化转化反应中最常用的载体材料之一。兼之炭材料表面极性、亲疏水性的可调变性,及对酸碱溶剂的反应惰性,也使其无论在学术研究还是在工业应用中都具有特殊的优势。另外,随着纳米炭材料科学的飞速发展,合成孔径、形貌、及表面官能团可控的介孔炭和具有多级孔道结构的多孔炭材料成为可能,将其应用到纤维素催化转化过程中,对深入理解孔道结构、表面官能团对纤维素转化的作用,揭示催化反应作用机制,指导炭基催化剂的设计合成,均具有重要意义。在本综述中,我们首先对纤维素转化中多孔炭的孔道结构和表面官能团性质的独特作用进行了阐述。由于商业活性炭的孔径一般在微孔尺度,但纤维素及可溶低聚糖的分子体积较大,因而其在活性炭中的传质受到了极大的限制。通过模板法获得的介孔炭材料,可实现孔径在2–10 nm的可控合成,大大提高了反应物的扩散速率,使之能与催化活性位有效接触。但孔道过于狭长,在反应过程中堵塞的可能性增高,进而导致催化剂失活;因此,在介孔孔道的基础上,建立互通的多级孔道结构对反应物、中间物、和产物的扩散,及催化活性的保持更为有利。另一方面,炭材料表面的含氧官能团不仅具有加强1,4-糖苷键吸附的作用,还可以作为酸性活性中心催化水解反应的进行;尤其是在传统的水相纤维素催化转化过程中,亲水表面对多孔炭催化剂与反应物的接触非常有利。本文以纤维素水解及纤维素水解加氢反应为例,展开讨论了多孔炭作为固体酸及双功能催化剂载体的应用。在水解反应中,纤维素首先在热水中降解为可溶低聚糖,之后再与活性炭表面官能团反应;其中多孔炭的比表面积、酸量、及酸强度均是促进水解发生的正向因素。在水解加氢反应中,炭载贵金属催化剂作为最常用的加氢催化剂,可获得以六元醇为主的纤维素转化产物。除了加氢作用之外,贵金属小颗粒被证实可以通过氢溢流作用提供水解所需的H+,同时,正价的贵金属也可促进反应过程中的氢转移。另一方面,由于钨物种可催化逆羟醛缩合反应的发生,因此在反应体系中引入钨物种时,水解加氢的主要产物由六元醇变为乙二醇。需要特别指出的是,在纤维素催化水解加氢的过程中,多孔炭材料作为载体同样具有非常重要的作用：一方面,三维介孔的孔道结构不仅有利于反应物、产物的扩散,也有利于加氢金属催化剂的分散,进而提高金属的催化加氢能力;另一方面,当炭材料的表面化学性质改变时,也会影响产物的选择性分布,例如当炭表面显碱性时,由于异构化作用,丙二醇成为主要产物。本文最后,我们列举了一些新型多孔炭材料,包括杂原子改性的多孔炭材料和金属氧化物-炭复合多孔材料的合成方法及其在纤维素催化转化乃至生物质转化中的潜在应用。     

Effect of surfactants on the porous structure of poly(<Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide) hydrogels prepared by an emulsion templating method

Stimuli-sensitive porous hydrogels prepared with an emulsion templating method developed by the authors are potentially applicable in the medical and pharmaceutical fields; thermosensitive N-isopropylacrylamide (NIPA) hydrogels having randomly distributed sphere-like cavities have been prepared by the polymerization in an aqueous phase in an oil-in-water (O/W) emulsion, followed by the washing of oil (oleyl alcohol) microdroplets. The surfactant plays a dominant role in the preparation of porous hydrogels and the pore size. This study concerns with the surfactant effects on the stability of pre-gel O/W emulsions. The porous NIPA hydrogels were successfully prepared using the surfactants forming the stable emulsion and their internal structures and swelling properties were characterized. The O/W emulsions and the porous hydrogels prepared using various amounts of oil and surfactant were characterized. The information obtained serves for preparation of porous hydrogels having suitable porous structure for their applications.     

ORGANIC GEOCHEMISTRY OF ARTIFICIALLY HEATED SPHAGNUM COAL CONSIDERED AS POSSIBLE SOURCE ROCK FOR OIL AND GAS

A preliminary study of simulated thermal maturity has been conducted to evaluate the oil, gas and hydrocarbon generation potential of sphagnum coal in the Jinsuo brown coal basin, Yunnan Province and to understand the characteristics of the element composition and biomarkers in the course of thermal alteration. The experimental result was compared with that of xylitic coal, a kind of lithotype of soft brown coal. It is considered that sphagnum coal possesses the potential of forming economic accumulation of oil and gas. Its highest proportion of oil and hydrocarbon generation is 510 mg/g Corg. and 232.1 mg/g Corg. respectively. At an R_(ran)~° value of 2.51%, the ratio of gas generation from sphagnum coal attains to 620.5 ml/g Corg. In view of sphagnum coal being different from the conventional soft brown coal in various respects such as coal forming raw materials and enviroments as well as physico-chemical properties, it is Suggested as a special kind of source rock for coal-generated oil and gas.     

Triazine interlinked covalent organic polymer as an efficient anti-bacterial agent

Herein, we report the synthesis of new covalent organic polymer comprising triazine and o-tolidine by solvothermal method. The formation of polymer was confirmed by Fourier transform infra red spectroscopy (FT-IR), cross polarization–magic angle spinning nuclear magnetic resonance (NMR), transmission electron microscopy, and scanning electron microscopy. Their antibacterial activity toward S. aureus (gram-positive) and P. aeruginosa (gram-negative) was assessed by the optical density measurements and direct contact method. These results have great significance toward the design of new porous polymers for antibacterial applications.     

Design and Construction of 3D Porous Na3V2(PO4)3/C as High Performance Cathode for Sodium Ion Batteries

An easy and delicate approach using cheap carbon source as conductive materials to construct 3D sequential porous structural Na3V2(PO4)3/C(NVP/C)with high performance for cathode materials of sodium ion battery is highly desired.In this paper,the NVP/C with 3D sequential porous structure is constructed by a delicate approach named as“cooking porridge”including evaporation and calcination stages.Especially,during evaporation,the viscosity of NVP/C precursor is optimized by controlling the adding quantity of citric acid,thus leading to a 3D sequential porous structure with a high specific surface area.Furthermore,the NVP/C with a 3D sequential porous structure enables the electrolyte to interior easily,providing more active sites for redox reaction and shortening the diffusion path of electron and sodium ion.Therefore,benefited from its unique structure,as cathode material of sodium ion batteries,the 3D sequential porous structural NVP/C exhibits high specific capacities(115.7,88.9 and 74.4 mA·h/g at current rates of 1,20 and 50 C,respectively)and excellent cycling stability(107.5 and 80.4 mA·h/g are remained at a current density of 1 C after 500 cycles and at a current density of 20 C after 2200 cycles,respectively).