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超临界CO2萃取反应合成碳酸二甲酯 总被引:4,自引:0,他引:4
实验测定了不同条件下碳酸二甲酯(DMC)、甲醇、乙二醇(EG)、碳酸乙烯酯(EC)在超临界相和液相中的分配系数,计算了DMC相对于其他组分的分离因子. DMC相对于甲醇的分离因子随EC浓度的升高而降低,随DMC和EG含量增加而升高,随压力增加而增大,随温度升高而变小. 这种变化规律表明利用超临界萃取与反应耦合提高酯交换反应转化率的前提是:(1) 反应体系中DMC的浓度要高,即进料中环氧乙烷(EO)的浓度要高,且EC转化率要高;(2) 低的反应温度和高的反应压力. 在160℃和5~20 MPa下,以环氧乙烷、甲醇和CO2为原料,考察了超临界CO2萃取与反应相耦合提高酯交换反应转化率的可行性. 研究结果表明,DMC与甲醇间的分离因子是影响超临界萃取反应操作过程中DMC收率的关键因素. 采用耦合技术可以提高DMC的单级收率约4%以上. 相似文献
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《Gas Separation & Purification》1991,5(3):173-176
A pressure swing adsorption (PSA) process for separating CO from a COCO2N2 mixture is proposed. The adsorbent used in this process is active carbon supported copper, which has been developed by this laboratory. By cycling the pressure of a bed of this adsorbent between ambient pressure and 20–30 Torr at room temperature, high purity CO can be obtained from the COCO2N2 gas mixture with a high recovery. The CO product purity depends crucially on the step of CO cocurrent purge after adsorption in the cycle and the regeneration of sorbent. 相似文献
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Li+, Na+//CO32-, B4O72-, Cl--H2O五元体系298K相平衡及平衡液相物化性质的研究 总被引:6,自引:0,他引:6
针对西藏扎布耶盐湖卤水组成,采用等温溶解平衡法研究了五元体系Li^ ,Na^ ∥CO3^2-,B4O7^2-,Cl^--H2O 298K下的相平衡关系。测定了该体系298K时各组份的溶解度及平衡液相的密度、粘度、折光率、电导率和pH值等物化性质,并绘制了该五元体系的溶解度空间立体图及平衡液相物化性质一组成图。实验表明:体系中共有3个四盐共饱点和6个单盐结晶区;无复盐和固溶体生成,也无碳酸氢盐存在:且LiCl对硼酸盐、Na2CO3对NaCl具有强烈的盐析作用。 相似文献
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Low critical temperature limits the application of CO2 trans-critical power cycle. The binary mixture of R290/CO2 has higher critical temperature. Using mixture fluid may solve the problem that subcritical CO2 is hardly con-densed by conventional cooling water. In this article, theoretical analysis is executed to study the performance of the zeotropic mixture for trans-critical power cycle using low-grade liquid heat source with temperature of 200 °C. The results indicated that the problem that CO2 can't be condensed in power cycle by conventional cooling water can be solved by mixing R290 to CO2. Variation trend of outlet temperature of thermal oil in super-critical heater with heating pressure is determined by the composition of the mixture fluid. Gliding temperature causes the maximum outlet temperature of cooling water with the increase of mass fraction of R290. There are the maximum values for cycle thermal efficiency and net power output with the increase of supercritical heating pressure. 相似文献
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K+/Cl-,Br- -H2O三元体系298 K,313 K,333 K时的相平衡 总被引:2,自引:0,他引:2
用等温溶解平衡法测定了三元体系 K /Cl-,Br--H2O 298 K、313 K、333 K时的相平衡数据,同时还测定了饱和溶液的密度、折光率等物化性质,依据湿渣法与X射线衍射相结合的方法对平衡固相组成进行了鉴定.该三元体系 298 K、313 K、333 K的溶解度等温图有 1 个固相区:K(Cl,Br),有 1 条单变量曲线,该体系属于固体溶液型.用Pitzer模型计算测得的三元体系 298 K、313 K、333 K溶解度,并用经验公式对平衡液相的密度、折光率进行了计算,计算值与实验值基本吻合. 相似文献
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The variation of refractive index of vitreous silica with purely hydrostatic pressure to 7 kbars was determined from the shift of the localized interference fringes across the specimen kept in an optical pressure bomb. Allowance for the change in the thickness of the specimen was made with the help of Murnaghan's finite-strain theory and the recently determined third-order elastic constants. The refractive index for λ 5893 A increases linearly with pressure with a slope of 9.2 × 10−4 /kbar up to 4 kbars; thereafter it increases nonlinearly. The increase in the refractive index, however, is linear with respect to the Lagrangian strain in the range investigated, except for a slight tendency for departure from linearity at the highest pressures. No hysteresis effects caused by permanent densification were noted. The results are interpreted in the light of Mueller's theory of photoelasticity of amorphous solids. 相似文献
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Jin Sung Choi Sang Hyuk Im Min Young Song O Ok Park Hansol Cho Jin Taek Hwang 《应用聚合物科学杂志》2005,95(5):1100-1104
A gradient refractive index rod was successfully prepared by a new fabrication method using laminar shear mixing, and a graded index polymer optical fiber that satisfied IEEE1394b was obtained from the method. To fabricate the gradient refractive index rod, a liquid monomer mixture with a relatively low refractive index was placed in a prepared cylindrical glass reactor and a transparent polymer rod with a higher refractive index was introduced at the center of the reactor. The reactor and the polymer rod were then rotated concurrently with a small rotating speed difference to generate a Couette flow in the liquid phase. The centrifugal force generated by rotation and the polymer diffusion into the liquid monomer mixture developed a graded concentration profile in a radial direction. The Couette flow could reduce the concentration fluctuation in a tangential direction. In addition, the graded index profile could be controlled by the copolymer composition of the rod and its diameter. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1100–1104, 2005 相似文献
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水合物的快速生成受诸多因素的影响,操作工况是其主要的影响因素之一。以67.7%CH4+32.3%CO2(摩尔分数)混合气为例模拟酸性天然气,采用自行设计的水合物动力学实验装置,分别对初始压力为3.0 MPa、3.5 MPa、4.2 MPa、5.0 MPa和实验温度分别为1.42 ℃、3.27 ℃、5.48 ℃、7.45 ℃时的水合物生成动力学进行实验研究。定义诱导期、平衡总耗时、生长速率为水合物动力学评价指标,指标通过分析水合物生成过程中的压力及气相组成变化得到,进而综合分析了操作工况对酸性天然气水合物生成动力学的影响。实验结果表明:初始压力越高,实验温度越低,水合物平衡时气相CO2的浓度越低,水合物的生成量和生长速率越大;此外,初始压力对体系诱导期影响不够显著,而操作温度的降低可以明显缩短体系诱导期。 相似文献
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Dietlind Adlercreutz Ernst Wehtje 《Journal of the American Oil Chemists' Society》2001,78(10):1007-1011
A simple HPLC method for the simultaneous analysis of phosphatidylcholine (PC), 1-acyl lysophosphatidylcholine (1-acyl LPC),
and 2-acyl lysophosphatidylcholine (2-acyl LPC) with refractive index detection is described. The separation of these three
compounds was achieved on a Waters (Milford, MA) Spherisorb amino phase column using a mixture of ethanol and an aqueous oxalic
acid solution as eluent. The optimal mixture of ethanol to oxalic acid solution was 92∶8 (vol/vol). PC and the two regioisomers
of LPC eluted within 15 min. The calibration curves were linear in a concentration range from 0.05 to 2.5 mM. Natural PC or
LPC eluted in a single peak, despite the diversity in the fatty acid composition. There was no rearrangement between 1-acyl
LPC and 2-acyl LPC during analysis or storage in ethanol within 23 h. This method is thus especially suitable for studying
reactions on PC and acyl migration in LPC. 相似文献
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An isocratic reversed-phase high-performance liquid-chromatographic method was developed for monitoring the lipase-catalyzed
hydrolysis of solid triglycerides in supercritical carbon dioxide. The reaction products obtained consist of free fatty acids,
monoglycerides, diglycerides, and unreacted triglycerides. For the method, developed with tripalmitin, a mobile phase of acetonitrile/chloroform/acetic
acid (50:50:1, vol/vol/vol), a C18 column, and refractive index detection were used. Analysis time is 7 min. Response factors were determined for each neutral
lipid class, which permitted quantitation of the hydrolysis product mixture. 相似文献
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为深入研究CO2开发CH4水合物对环境的影响,从而实现长期储存CO2和开发新能源CH4水合物的目的.本研究主要考察了不同温度下(1-7 ℃),CH4+CO2混合气在纯水和NaCl溶液(质量分数3.6%)中的生成水合物时的溶解相平衡.考察了温度和盐对溶解相平衡的影响.并将实验值与Chen-Guo水合物模型计算值进行了比较... 相似文献
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《Ceramics International》2022,48(1):120-129
Ceramic mask stereolithography additive manufacturing technology has the abilities of fast and accurate printing complex and personalized ceramic parts. However, since the ultraviolet light is strongly blocked by the ceramic particles in the slurry during exposure, the slurry with high refractive index ceramic particles has low cure depth, and serious light scattering. This investigation developed a curable silicon nitride slurry with a high refractive index liquid phase, which significantly reduced the refractive index difference between the liquid phase and the silicon nitride ceramic particles. The high refractive index acrylate monomer and solvent were chosen to increase the cure depth while ensuring the curing accuracy. Compared with the slurry whose liquid phase was pure HDDA, the addition of OPPEA and ACMO in the liquid phase showed a better refractive index increasing effect and the strongest cure depth and dimensional accuracy improvement. POE was verified as a suitable non-reactive high refractive solvent. The composition of 20 wt% OPPEA, 10 wt% ACMO, 40 wt% HDDA, and 30 wt% POE were optimized as the high refractive index liquid phase for 40 vol% solid phase silicon nitride slurry. A finite element analysis model of silicon nitride slurry was established, and the distribution of ultraviolet light intensity in silicon nitride slurry with high refractive index liquid phase was numerically simulated. 相似文献
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The hydroformylation reaction in supercritical carbon dioxide or CO2-expanded liquids (CXLs) has many advantageous properties. However, accurate phase behavior and equilibrium must be known to properly understand and engineer these systems. In this investigation, the vapor-liquid equilibrium and mixture critical points of CO2 systems with 1-octene, nonanal, 1-octene and nonanal mixtures, and mixtures of 1-octene, nonanal and syngas (CO/H2) were measured at 60 °C up to 120 bar of pressure. The Peng-Robinson equation of state with van der Waals two-parameter mixing rule was employed successfully to correlate the binary mixture data and predict the ternary mixture data. The presence of CO/H2 pressure increased the mixture critical points and decreased the volume expansion at any given pressure. In an actual reaction, the mixture critical point would increase throughout the reaction, while the volume of the liquid phase would decrease. These data will aid the understanding and reaction engineering for the hydroformylation reaction in CO2-expanded liquids and supercritical fluids. 相似文献
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Studies of the mechanical and optical properties of undrawn uniaxially stretched polyester PET (Egyptian manufacture) fibers by annealing and cold drawing were performed. The optical properties and strain produced in PET fibers at different conditions were measured interferometrically at room temperature. A two‐beam interferometric technique was used to determine refractive indices and birefringence of the investigated PET samples with strain produced by different stresses. Using a microstrain device attached to a microscope stage and through the application of the appropriate mathematical equations, the refractive indices and the birefringence values were determined as a function of the draw ratios. The resulting data were utilized to calculate the polarizability per unit volume, the number of molecules per unit volume, Poisson's ratio, the strain optical coefficient, and several other parameters and constants. Also, some structural parameters are determined, such as form birefringence, the virtual refractive index, the harmonic mean polarizability of the dielectric, the harmonic mean specific refractivity, and the isotropic refractive index. The generalized Lorentz–Lorenz equation given by de Vries is used to determine PET fiber structure parameters. Comparison between the results have been compared with Hermans' optical orientation function. Relationships between the various optical parameters and the draw ratios are plotted, and the effect of draw ratio on the refractive index profile is studied. Microinterferograms are given for illustration. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1869–1880, 1999 相似文献
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本文介绍一种新型气相色谱固定相——碳分子筛(KMS),其最大的优点是在常温下,单柱即可同时分离分析H_2、O_2、N_2、CO、CH_4、CO_2六种混合气体,柱子的保留值重现性好,峰形对称,柱效高。本文求得了在H_2和Ar作载气时KMS对上述六种气体的定性定量特性,配气的定量结果总的平均相对误差为3.67%。同时这种碳分子筛原料易得,制作简单,成本便宜。 相似文献
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D. G. McConnell R. L. Hoffmann G. J. Elman C. D. Evans 《Journal of the American Oil Chemists' Society》1967,44(11):641-644
The elution characteristics of methanol-benzene solvent systems were determined by separating a mixture of polar and nonpolar
fatty methyl esters by liquid chromatography on silicic acid columns. A series of curves were plotted showing the relationship
between the elution volume of each component and methanol concentration of the stationary phase. The resulting graphs serve
as a basis for predicting elution conditions for separating other polar materials. Adsorption isotherms were plotted from
equilibrium studies of methanol-benzene systems on silicic acid. Methanol concentrations of the effluents from various columns
were determined by refractive index. An abrupt concentration change occurs in the methanol content of the effluent when the
mobile solvent is either richer or poorer in methanol than the equilibrated solvent. Elution position of this abrupt change
depends upon the concentration of methanol in both the mobile and the stationary phases. The procedure has been rigorously
standardized because small variations in the amount of methanol on the column create large differences in elution volumes.
No. Util. Res. and Dev. Div., ABS, USDA. 相似文献
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Tanja Kugler Dr.‐Ing. Michael Heinrich Rausch Prof. Dr.‐Ing. Andreas Paul Fröba 《化学,工程师,技术》2013,85(5):732-739
Binary diffusion coefficients Dij were determined for mixtures of argon and neon over the entire composition range using a Loschmidt cell at 293.15 – 333.15 K and 1 – 10 bar. Before the measurements, the different pure gases were added into the two half‐cells of the Loschmidt cell. After connecting both half‐cells, the change in partial molar density, or rather in the refractive index has been detected simultaneously as a function of position and time within each half‐cell using holographic interferometry. The binary diffusion coefficients obtained for the upper half‐cell show systematic deviations from literature data. In contrast, the data measured in the lower half‐cell are in excellent agreement with literature. Within the measurement uncertainty, the product of the molar density of the mixture and Dij is not affected by the pressure. 相似文献
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研究了二个三元体系Li+/CO32-、 B4O72-H2O(1)和K+/CO3(2-)、 B4O7(2-)-H2O(2) 298K时的相平衡液相的物化 性质(密度、折光率、粘度、电导率、pH值)。研究表明:这二个三元体系均属简单共饱型,无复盐或固溶体形 成。体系(1)的两段溶解度曲线对应于无水Li2CO3和Li2B4O7H2O结晶区,体系(2)的两段溶解度曲线对应于 K2CO3·3/2H2O和K2B4O7·4H2O结晶区。用经验公式对平衡液相的密度、折光率进行了计算,计算值与实验值非常 吻合,最大绝对偏差仅为0.0011。 相似文献