Sorption and pervaporation separation of ethyl tert—butyl ether and ethanol mixtures through a blended membrane

A new kind of membrane was prepared by blending poly(acrylic acid) with cellulose acetate propionate for the separation of ethyl tert—butyl ether and ethanol mixtures. The properties of the membranes were evaluated by the pervaporation separation of mixtures of ethyl tert—butyl ether/ethanol and the sorption experiments. The experimental results showed that the selectivity and the fluxes of this membrane depend on the blend composition and on that of processed feed mixtures. With respect to temperature, the ethanol fluxes obey the Arrhenius equation. The fluxes increase with the increase of the poly(acrylic acid) content in the blended membrane, the ethanol concentration in the feed, and the experimental temperature. But the selectivity decreases as the poly(acrylic acid) content and the experimental temperature are raised up. When the feed composition is varied, this membrane shows the special characteristics at the azeotropic composition. In the vicinity of the azeotropic point, the minimum values of ethanol concentration in the permeate and in sorption solution are obtained. The swelling ratios increase with an increase in the temperature and the ethanol concentration. The ethanol concentration in the sorption solution is also influenced by the temperature and composition of the mixtures. When the temperature increases, the sorption selectivity of the membrane decreases. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1631–1638, 1997     

Permeation behaviour in cellulose triacetate dense membrane during pervaporation separation of methanol/methyl tert-butyl ether mixture

The pervaporation separation of methanol/methyl tert-butyl ether through cellulose triacetate dense membranes has been carried out under different feed compositions, permeation temperatures and temperature cycles to investigate the permeation behaviour of the membrane during pervaporation process. The experimental data indicate that the plasticization effect has a decisive influence on pervaporation flux, permselectivity and permeation activation energy. The results show that the penetrants of different feeds are transported through the membrane by different pathways with the influence of plasticization effect at different temperatures. It has also been observed that plasticization had great effect on the membrane swelling and sorption selectivity. Furthermore, DSC results show that the membranes retain the influence of the plasticization effect after pervaporation separations are tested. © 2000 Society of Chemical Industry     

汽油抗爆剂甲基叔丁基醚合成研究进展

根据原料的不同,对汽油抗爆剂甲基叔丁基醚的合成方法进行了综述。威廉逊合成法因为原料昂贵只适用于少量合成;甲醇和叔丁醇脱水醚化合成甲基叔丁基醚由于原料相对便宜,既可以用于实验室合成,也可以推广至工业化生产;甲醇和异丁烯反应生产甲基叔丁基醚是目前最主要的工业化生产方法。由于异丁烯来源受限,利用廉价原料生产异丁烯成为甲基叔丁基醚合成中的重要研究方向,也有以非异丁烯为原料的甲基叔丁基醚合成路线研究。     

用于脱除C5及MTBE中甲醇的渗透汽化膜研究

Several pervaporation membranes, cellulose acetate (CA), polyvinylbutyral (PVB), poly(MMA-co-AA), MMA-AA-BA, CA/PVB blend and CA/poly(MMA-co-AA) blend, were prepared, and their pervaporation properties were evaluated by separation of methanol/C5 or methanol/MTBE (methyl tert-butyl ether). The results shows that the CA composite membrane has a high separation performance (flux Jmenthanol =350g.m-2.h-1 and separation factor a > 400) for methanol/C5 mixtures, and the pervaporation characteristics of MMA-AA-BA copolymer membranes changes with the ratio of copolymer. For CA/poly(MMA-co-AA) blend membrane, the pervaporation performance is improved in comparison with CA or poly(MMA-co-AA) membrane. From the experiment of CA/PVB blend membranes for methanol/MTBE mixture, it is found that the compatibility of blends may affect the separation features of blend membrane.     

甲基叔丁基醚的状态方程

利用公开发表的实验数据开发了甲基叔丁基醚（MTBE）的状态方程,方程以Helmholtz自由能为显式、以温度和密度为自变量。方程计算饱和蒸气压的不确定度430 K以下为1.0%,随着温度的升高,由于缺少实验数据不确定度增大为2.0%。方程计算密度的不确定度由液相区的0.2% 变到临界区和气相区的1.0%。方程计算能量相关物性（如比热容和音速）的不确定度为0.5%。临界区,除了饱和蒸气压,方程计算所有其它热力学性质的不确定度都较高。正如文中分析,本文方程不但能准确的复现实验数据,而且方程的外推性也是合理的。文中对方程进行了详细的分析。     

PDMS/陶瓷复合膜用于正丁醇-水体系的渗透汽化分离

Pervaporation has attracted considerable interest owing to its potential application in recovering biobutanol from biomass acetone-butanol-ethanol (ABE) fermentation broth. In this study, butanol was recovered from its aqueous solution using a polydimethylsiloxane (PDMS)/ceramic composite pervaporation membrane. The effects of operating temperature, feed concentration, feed flow rate and operating time on the membrane pervaporation per-formance were investigated. It was found that with the increase of temperature or butanol concentration in the feed, the total flux through the membrane increased while the separation factor decreased slightly. As the feed flow rate increased, the total flux increased gradually while the separation factor changed little. At 40 C and 1% (by mass) butanol in the feed, the total flux and separation factor of the membrane reached 457.4 g•m2•h1 and 26.1, respec-tively. The membrane with high flux is suitable for recovering butanol from ABE fermentation broth.     

用于脱除C5及MTBE中甲醇的渗透汽化膜研究

Several pervaporation membranes, cellulose acetate (CA), polyvinylbutyral (PVB), poly(MMA-co-AA),MMA-AA-BA, CA/PVB blend and CA/poly(MMA-co-AA) blend, were prepared, and their pervaporation properties were evaluated by separation of methanol/C5 or methanol/MTBE (methyl tert-butyl ether). The results shows that the CA composite membrane has a high separation performance (flux Jmethanol = 350 g.m-2.h-1 and separation factor α＞400) for methanol/C5 mixtures, and the pervaporation characteristics of MMA-AA-BA copolymer membranes changes with the ratio of copolymer. For CA/poly(MMA-co-AA) blend membrane, the pervaporation performance is improved in comparison with CA or poly(MMA-co-AA) membrane. From the experiment of CA/PVB blend membranes for methanol/MTBE mixture, it is found that the compatibility of blends may affect the separation features of blend membrane.     

Phase diagrams for oil/methanol/ether mixtures

One-phase transmethylations of vegetable oils with methanol to form methyl esters occur considerably faster than conventional two-phase reactions. Addition of simple ethers is an efficient method for producing a single phase. Ternary phase diagrams have been determined at 23°C for oil/methanol/ether mixtures; these are useful when applying the one-phase method across a wide range of conditions. Soybean, canola, palm, and coconut oils were used in combination with five ethers, namely, tetrahydrofuran (THF), 1,4-dioxane (DO), diethyl ether (DE), diisopropyl ether (DI), andtert-butyl methyl ether (TBM). All five ethers can produce miscibility for all methanol/oil compositions. The ether/methanol volumetric ratios required for miscibility at a methanol/soybean or canola oil volumetric ratio of 0.20 (5.4 molar ratio) at 23°C are: THF, 1.15; DO, 1.60; DE, 1.38 DI, 1.57; and TBM, 1.57. For THF, this results in one-phase mixtures that contain 65 vol% oil. Soybean and canola oil form identical diagrams. Palm oil requires slightly less ether at the lower methanol concentrations, but coconut oil requires considerably less across the whole concentration range. Acid-catalyzed reactions, when performed at the boiling point of the most volatile component, require less ether than predicted from the diagrams.     

Effects of polymer solvents on the performance of cellulose acetate membranes in methanol/methyl tertiary butyl ether separation

The performances of cellulose acetate membranes prepared with casting solutions, with acetone, dimethylformamide (DMF), and N‐methylpyrrolidone (NMP) as solvents, were studied in a series of methanol/methyl tertiary butyl ether separation experiments. The flux and selectivity of the membrane samples were affected by the type of solvent used to prepare the casting solution. The sample with DMF consistently gave the highest selectivity and lowest flux, followed by the samples with NMP and acetone. The differences in the performances were attributed to the effects of the volatility and evaporation rates of the solvents. Scanning electron microscopy and atomic force microscopy techniques were used for comparing the morphologies of the membranes. In addition, we used Raman spectroscopy as a novel technique to study the sorption selectivities of the membrane samples prepared with the three different solvents. In a parallel study, the relation between the polymer concentration in the casting solution and the morphology and performance of the membrane samples was studied. Under similar preparation conditions, the morphology of the membrane changed from being porous to being dense when the membrane was prepared with casting solutions with increasing polymer concentration. Also, the selectivity increased and the permeability decreased with increasing polymer concentration in the casting solution. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2882–2895, 2001     

Effect of compatibility of cellulose acetate/poly(vinyl butyral) blends on pervaporation behavior of their membranes for methanol/methyl tert‐butyl ether mixture

Binary blends and their blend membranes of cellulose acetate (CA) and poly(vinyl butyral) (PVB) are prepared by solution blending. The compatibility of the blends is studied by viscometry and Fourier transform IR. It is found that the incompatibility of the blends is markedly manifested when the weight fraction of PVB in the CA/PVB blends (W_PVB) is located at higher regions. On the other hand, compatibility is obtained for the CA/PVB blends with lower W_PVB values, especially at about 0.2. This compatibility is believed to play a key role in the good pervaporation behavior of CA/PVB blend membranes. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2434–2439, 2002     

渗透汽化膜分离MeOH/MTBE混合物的传质分析——单组分在膜中的扩散

用石英晶体微平衡法测定了298.15 K、305.75 K、312.95 K下MeOH（甲醇）和MTBE（甲基叔丁基醚）在CA（醋酸纤维素）膜中的吸着平衡数据和吸着动力学数据.结果表明：MeOH和MTBE在CA膜中的传质过程属于Fick扩散类型;MeOH在CA膜中的平衡吸着量和扩散系数都比MTBE大,说明CA膜对MeOH/MTBE混合物有较好的分离性能;同一吸着温度下,吸着速度和平衡吸着量均随着吸着蒸气压的升高而升高;可用Eyring的扩散“空穴”理论解释MeOH和MTBE在膜中的扩散行为.     

甲基叔丁基醚饱和液相导热系数的实验研究

利用瞬态双热线法测量了243—403 K温度范围内饱和液相甲基叔丁基醚的导热系数,并将实验数据拟合为温度的关联式。实验数据与导热系数关联式计算结果的标准偏差和最大偏差分别为0.30%和0.89%,导热系数的合成标准不确定度小于±1.0%。甲基叔丁基醚导热系数的实验研究为正在进行的甲基叔丁基醚替代物筛选提供急需的基础热物性数据,对改进汽油、柴油质量,提高油品的环境友好性及推广使用清洁燃料方面有重要价值。     

Characterization and preparation of polyion complex composite membranes for the separation of methyl tert‐butyl ether/methanol mixtures

A series of polyion complex (PIC) composite membranes composed of sodium alginate (SA) polyanion and chitosan polycation were prepared by varying the ratio of concentration. The interaction between SA and chitosan was investigated by FTIR, SEM, and X‐ray analysis and was related to mechanical properties and the swelling phenomenon. The overall PIC composite membranes showed the following results: the total thickness of the coating layer was thicker than that of pure SA composite, and increased with increasing the concentration of chitosan solution during PIC formation. This result was attributed to the diffusion of chitosan molecules from the liquid solution into the SA matrix, and the incorporation with SA molecules. For the PIC membranes prepared with different concentrations of polymer solution, their structural differences could not be detected from IR spectra but their morphological differences could be noticeably found from SEM. Furthermore, the amorphousness of PIC membranes and their elongation properties at break increased significantly as a function of polymer contents, whereas the tensile modulus decreased because of the physical transition effect. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 714–725, 2002     

Pervaporation separation of MTBE–methanol mixtures using cross‐linked PVA membranes

Poly(vinyl alcohol)(PVA)/poly(acrylic acid)(PAA) and PVA/sulfosuccinic acid (SSA) membrane performances have been studied for the pervaporation separation of methyl tert‐butyl ether (MTBE)/methanol (MeOH) mixtures with varying operating temperatures, amount of cross‐linking agents, and feed compositions. Typically, the separation factor, about 4000, and the permeation rate, 10.1 g/m²/h, were obtained with PVA/PAA = 85/15 membrane for MTBE/MeOH = 80/20 mixtures at 50°C. For PVA/PAA membranes, it could be considered that the flux is affected by the structural changes of the membranes due to the cross‐linking and the free carboxylic acid group also took an important role in the separation characteristics through the hydrogen bonding with PVA and the feed components leading to the increase of flux. The latter membrane of the 5% SSA membrane shows the highest separation factor of 2095 with the flux of 12.79 g/m²/h for MTBE/MeOH = 80/20 mixtures at 30°C. Besides the swelling measurements were carried out for pure MTBE and MeOH, and MTBE/MeOH = 90/10, 80/20 mixtures using PVA/SSA membranes with varying SSA compositions. It has been recognized that there are two factors, the membrane network and the hydrogen bonding in the swelling measurements of PVA/SSA membranes. These two factors act interdependently on the membrane swelling. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1699–1707, 2000     

Development of methanol selective membranes for separation of methanol–methyl tertiary butyl ether mixtures by pervaporation

Several copolymers of acrylonitrile (AN) were synthesized. Methanol selective membranes were prepared from these copolymers of AN. The other monomers in the copolymers were selected on the basis of their solubility parameter values relative to those of methanol. These were hydroxyethyl methacrylate, methacrylic acid, and vinyl pyrrolidone. Thus, pervaporative separation of methanol from its mixture with methyl tertiary butyl ether over the entire concentration range of 0–100% methanol was studied using these copolymer membranes of AN. For each copolymer of AN three different membranes with different copolymer compositions were prepared. Copolymers of AN with hydroxyethyl methacrylate and methacrylic acid showed high selectivity and moderate flux for methanol (2561, 773, 0.057, and 0.045 kg/m² h, respectively, with a membrane of 50‐μm thickness for a feed mixture containing 5% methanol at 30°C). A copolymer of AN with vinyl pyrrolidone showed comparable flux, but methanol selectivity of this membrane was poor. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2645–2659, 1999     

Pervaporation separation of meOH/MTBE through CTA membrane

In the present work, the pervaporation (PV) separation of a MeOH/MTBE mixture system was studied using a CTA dense membrane. The PV performances were characterized by changing the operating conditions, such as the feed composition and permeation temperature. The results show that the CTA membrane favors MeOH permeation and exhibits specificity during the PV separation process for the MeOH/MTBE system due to the existence of the plasticization effect from the MeOH component. Furthermore, the swelling sorption measurements reaffirm that the plasticization effect has a dominant effect on the transport of the penetrants through the membrane and substantially determines the PV permeation properties. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 377–386, 1999     

Pervaporation separation of a water/ethanol mixture by a sodium sulfonate polysulfone membrane

A sodium sulfonate polysulfone membrane was prepared for the dehydration of a water/ethanol mixture by pervaporation. The separation performances of water and ethanol were examined by the testing of the ethanol/water mixture under operating conditions. The permselectivity of the sodium sulfonate polysulfone membrane was found to strongly depend on the sodium content in the membrane. The sodium sulfonate ratio showed a significant influence on the hydrophilicity and diffusion behavior of the polysulfone membrane. Moreover, the difference in the diffusion of the permeates played an important role in the sulfonate polysulfone membrane. It was found that a high‐performance pervaporation membrane could be achieved with a sodium sulfonate polysulfone membrane. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3374–3383, 2003     

Pervaporation of methanol/methyl tert‐butyl ether mixtures through agarose/hydroxyethylcellulose blended membranes

In this study, we investigated methanol (MeOH)/methyl tert‐butyl ether (MTBE) separation with hydroxyethylcellulose (HEC)/agarose blended membranes by applying a pervaporation technique. The membranes permeated MeOH in preference to MTBE from MeOH/MTBE mixtures. From pervaporation and sorption data, the permselectivity of HEC/agarose blended membrane was dominantly due to solubility selectivity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3408–3411, 2002     

强化菌株NERC0401去除水体中的甲基叔丁基醚

为强化菌株NERC0401对污染水体中难降解物甲基叔丁基醚（MTBE）的去除,采用间歇方法考察了海藻酸钠浓度、氯化钙浓度、包埋固定化小球粒径、添加物以及共存有机物对包埋固定化菌株NERC0401去除MTBE的影响。结果表明,在海藻酸钠和氯化钙浓度均为2%以及包埋小球粒径约为1.50 mm的条件下,固定化菌株具有较好的生物活性,对MTBE的生物去除率在55%以上,优于游离态菌株;当添加0.5%的活性炭后,其去除效果可得到提升;质量浓度约200 mg/L的乙醇的存在也会对生物去除MTBE产生一定的强化作用。