Study on the influence of SDS and THF on hydrate-based gas separation performance

Hydrate additives can be used to mitigate hydrate formation conditions, promote hydrate growth rate and improve separation efficiency. CO₂ + N₂ and CO₂ + CH₄ systems with presence of sodium dodecyl sulfate (SDS) or tetrahydrofuran (THF) are studied to analyze the effect of hydrate additives on gas separation performance. The experiment results show that CO₂ can be selectively enriched in the hydrate phase. SDS can speed up the hydrate growth rate by facilitating gas molecules solubilization. When SDS concentration increases, split and loss fraction increase initially and then decrease slightly, resulting in a decreased separation factor. The optimum concentration of SDS exists at the range of 100–300 ppm. As THF can be easily encaged in hydrate cavities, hydrate formation condition can be mitigated greatly with its existence. Additionally, THF can also strengthen hydrate formation. The THF effect on separation performance is related to feed gas components. CO₂ occupies the small cavities of type II hydrate prior to N₂. But the competitiveness of CO₂ and CH₄ to occupy cavities are quite fair. The variations of split fraction, loss fraction and separation factor depend on the concentration of THF added. The work in this paper has a positive role in flue gas CO₂ capture and natural gas de-acidification.     

Influence of Reaction Conditions on Enzymatic Enantiopreference: the Curious Case of HEwT in the Synthesis of THF-Amine

Enzymatic enantiopreference is one of the key advantages of biocatalysis. While exploring the synthesis of small cyclic (chiral amines) such as 3-aminotetrahydrofuran (THF-amine), using the (S)-selective transaminase from Halomonas elongata (HEwT), inversion of the enantiopreference was observed at increasing substrate loadings. In addition, the enantiopreference could be altered by variation of the ionic strength, or of the co-solvent content in the reaction mixture. For example, using otherwise identical reaction conditions, the presence of 2 M sodium chloride gave (R)-THF-amine (14 % ee), while the addition of 2.2 M isopropyl alcohol gave the (S)-enantiomer in 30 % ee. While the underlying cause is not currently understood, it appears likely that subtle changes in the structure of the enzyme cause the shift in enantiopreference and are worth exploring further.     

PBT装置THF生成控制

研究了在直接酯化法合成PBT时THF的生成规律以及抑制THF生成的方法。合适的催化剂添加的质量分数为60×10-6左右,PTA与BDO的量比为1∶2.9～1∶3.0,酯化温度控制在242℃以下,可以降低THF生成量。     

Enhancing the yield of polycarbosilane synthesis via recycling of liquid by-product at atmospheric pressure

Polycarbosilane (PCS) is a typical ceramic precursor for the fabrication of SiC fibers and SiC matrix composites. However, it is still costly and not widely employed in industry, mainly due to its low yield by typical chemosynthesis methods.In this work, we reported for the first time a novel method to significantly increase the PCS yield from 51.3% to 62.8% by recycling the liquid by-products (LBP), which was mainly made up of low-molecular-weight PCS, as revealed by FT-IR, GPC, and NMR analysis. The results showed that recycling LBP did not alter the chemical structure of the PCS products, making it very promising for mass production and application of PCS at the industrial scale.     

去除杂质后玉米黄质晶体中溶残脱除方法研究

玉米黄质和叶黄素是两种仅存于人眼睛中的类胡萝卜素,在保护视力、预防老年黄斑变性和白内障方面起着重要的作用,而工业化生产玉米黄质一般均由叶黄素经异构化所得,该种方法制备的玉米黄质往往含有一定数量的杂质,影响了其在食品、医药、化妆品等诸多方面的应用。本实验以玉米黄质含量和THF以及丁酮残留量为指标,考察了丁酮的添加方式、添加体积以及搅拌温度和搅拌时间以及丁酮用量对去除杂质后的玉米黄质中溶残的去除方法的影响。实验结果表明,玉米黄质经THF溶解除去杂质后蒸干,添加30倍丁酮,70℃搅拌8h,玉米黄质含量达81.2%,且THF和丁酮可以得到有效去除。经反复实验验证,该工艺所得玉米黄质不仅含量有所提高,且杂质和溶剂残留均可得以有效去除,可以用于工业化生产。     

Fundamentals, processes and applications of high-permittivity polymer-matrix composites

There is an increasing need for high-permittivity (high-k) materials due to rapid development of electrical/electronic industry. It is well-known that single composition materials cannot meet the high-k need. The combination of dissimilar materials is expected to be an effective way to fabricate composites with high-k, especial for high-k polymer-matrix composites (PMC). This review paper focuses on the important role and challenges of high-k PMC in new technologies. The use of different materials in the PMC creates interfaces which have a crucial effect on final dielectric properties. Therefore it is necessary to understand dielectric properties and processing need before the high-k PMC can be made and applied commercially. Theoretical models for increasing dielectric permittivity are summarized and are used to explain the behavior of dielectric properties. The effects of fillers, fabrication processes and the nature of the interfaces between fillers and polymers are discussed. Potential applications of high-k PMC are also discussed.     

四氢呋喃在岩样原油抽提中的应用

本文在充分了解和认识原油组份及溶剂性质的基础上,通过实验对比,遴选出四氢呋喃作为新一代岩样残存抽提溶剂。该抽提溶剂除了具有沸点相对较低、粘度较低、分子极性较高、水溶性好等利于抽提原油的优点外,特别还具有近乎无毒的显著特性。使用四氢呋喃抽提岩样原油能大大改善工作环境和提高工作效率,还能有效防止抽提溶剂对大气环境的污染。用四氢呋喃抽提岩样残存原油的方法在国内外相关技术资料中尚未发现。目前该方法已申请专利并受理。     

Effect of Water on Adsorption Behavior at Polymer/γ-Fe2O3 Interface

The adsorption behavior of a hydroxylated polymer onto γ-Fe₂O₃ particles in a tetrahydrofuran/water solvent system was investigated. The saturation adsorption of the polymer decreased with an increase in the water content of the solvent system, and the degree of dispersion of the magnetic particles in the paint also decreased. It was shown that the water located not at the interface between the particles and the solution but in the solution. Water interacted with the polymer and increased the radius of gyration of the polymer in solution. Thus, the polymer did not interact with the particles, and the particles were prevented from having a high dispersion.     

四氢呋喃、水、1,4-丁二醇三元系汽液平衡数据的测定与关联

用流动法测定了四氢呋喃、水、１，４－丁二醇三元大沸点差体系汽液平衡，将实测数据与作者先前回归得到的二元体系Ｗｉｌｓｏｎ模型参数的推算值进行了比较，结果比较吻合。     

低场核磁共振在研究四氢呋喃水合物形成过程中的应用

目前关于含四氢呋喃（THF）水合物形成过程的研究多采用间接法,由于这些方法都不是直接测量反应物或生成物的量,其研究结果受实验环境、仪器精度以及计算误差的影响较大。为此,突破传统的检测技术手段,采用低场核磁共振技术研究了19%THF水溶液从室温开始到水合物形成过程中试样的T₂时间（氢核横向弛豫时间）分布和核磁总信号量随温度的变化,以探讨THF水合物形成过程的特征。实验结果表明：T₂分布和核磁总信号量均与温度有较好的相关性,说明THF水合物的生成与温度密切相关。根据核磁总信号的变化将THF水合物的整个生成过程划分为4个阶段：初始期、诱导期、加速生长期和稳定期：在诱导期阶段的物质组成具有随机性,有水合物簇出现,但这些水合物簇不稳定,随机的分解和长大,导致此阶段的核磁总信号有一定的波动。当经过诱导期后,水合物簇尺寸达到晶核临界尺寸,水合物开始大量生成。且随着水合物的生成,THF溶液逐渐消耗,生成速度逐渐变慢,直到达到稳定期。