Pd/Al2O3膜的制备及其对 1,5-环辛二烯加氢的催化性能

利用微乳液浸渍技术制备了负载型Pd/Al2O3膜,并用扫描电镜和原子吸收光谱对微乳液中的纳米Pd颗粒及其在Al2O3陶瓷膜载体上的形貌、分布和负载量进行了表征.在"催化接触器"型膜反应器中,以1,5-环辛二烯(COD)加氢作为模型反应考察了Pd/Al2O3膜的催化性能.结果表明,采用微乳液技术制备Pd/Al2O3膜时,Pd负载量、浸渍操作方式、焙烧温度和载体孔径对Pd/Al2O3膜的催化性能有一定影响.要获得对COD加氢反应的高催化活性和较高的中间产物环辛烯选择性,优化的Pd/Al2O3膜制备条件为:缓慢析出Pd纳米颗粒,同时采用循环浸渍方式,焙烧温度300℃,膜载体孔径1.9μm.     

多孔Pd/α-Al2O3 活性膜上 1,5-环辛二烯选择加氢

利用微乳液及浸渍技术制备了多孔Pd/α-Al2O3催化活性膜.利用透射电镜、扫描电镜和X射线衍射对微乳液中及α-Al2O3陶瓷膜孔结构中纳米Pd颗粒的形貌和分布进行了表征.分析结果表明,通过浸渍技术,微乳液中的纳米Pd颗粒以几百纳米大小的晶体形态均匀负载于陶瓷膜孔中.在"催化接触器"型膜反应器中,以1,5-环辛二烯催化加氢为模型反应,考察了多孔Pd/α-Al2O3膜的活性与选择性,并与Pd-聚丙烯酸(PAA)有机催化膜反应器、悬浮床反应器和固定床反应器中的催化性能进行了比较.结果表明,Pd/α-Al2O3膜反应器的催化活性与目的产物1-环辛烯的选择性远高于Pd-PAA有机膜反应器和固定床反应器.Pd/α-Al2O3膜反应器在强化传质和消除孔内扩散方面效果显著,这与Pd在陶瓷膜孔中的分布及反应物在膜反应器中的高速流动有关.     

反相微乳液化学剪裁制备明胶-γ-Fe2O3纳米复合微粒

复合纳米微粒;反相微乳液化学剪裁制备明胶-γ-Fe2O3纳米复合微粒     

聚醚类破乳剂的界面扩张流变性质

采用悬挂滴方法研究了不同结构聚醚类破乳剂与煤油间的界面张力及界面扩张流变性质. 结果表明, 4种聚醚类破乳剂均具有较强的降低界面张力能力, 且支链化程度越低分子在界面上排列越紧密, 直线型破乳剂在低浓度条件下界面张力最低. 破乳剂的分子尺寸较大, 慢弛豫过程控制界面膜性质, 吸附膜以弹性为主. 同时, 柔性聚氧乙烯链和聚氧丙烯链对界面膜性质的影响较大, 随着支链化程度增大, 界面分子间相互作用增强, 界面膜弹性增强, 黏性降低.     

Pd-CeO2/Al2O3结构对其催化加氢脱硫反应性能的影响

分步浸渍法制备了不同Pd含量的Pd-CeO2/Al2O3催化剂,以噻吩加氢脱硫为探针反应,考察了Pd-CeO2/Al2O3催化剂的加氢脱硫性能,并应用XRD、H2-TPR、NH3-TPD、H2吸附和CO吸附等手段对催化剂结构进行了表征.结果表明,Pd在制备过程巾优先沉积在CeO2表面,Pd-Ce结合作用导致了界面效应和新的酸性位产生,Pd-Ce之间的界面效应是Pd-CeO2/Al2O3催化剂加氢脱硫活性提高的原因.2%Pd的Pd-CeO2/Al2O3催化剂拥有最高的单位质量Pd上的界面酸量,改性效果最为明显.Pd颗粒的优势面是Pd(111)面,这导致了强的Pd-Ce结合作用和界面效应,而1%和4%Pd的Pd-CeO2/Al2O3催化剂由于Pd-ce结合的空间结构使界面效应削弱,活性提高不明显.     

基于酸碱相互作用制备染料杂化的聚磷腈微粒及其乳化性能

利用罗丹明B(RhB)通过酸碱相互作用对聚(环三膦腈-co-4,4′-二羟基二苯砜)(PZS)微粒进行表面改性,得到一种染料杂化的聚磷腈胶体粒子(PZS@RhB),对其结构、形貌、亲-疏水性及pH响应性进行了表征;进一步以PZS@RhB微粒为颗粒乳化剂,研究了其乳化性能,并探讨了乳液的破乳条件及机理.结果表明:PZS微粒表面吸附RhB后,疏水性增加,且RhB结构中的羧基赋予了微粒pH响应性;当水相中PZS@RhB微粒的质量浓度达到14 mg/mL时,可乳化甲苯形成较为细腻的W/O型乳液;乳液呈现出显著的pH响应性,当增加水相pH至强碱性(pH≥10.11)时,乳液可发生相反转,由W/O型转变为O/W型;此外,通过向乳液中加入三乙胺,可有效破环PZS微粒与RhB之间的酸碱相互作用,从而方便实现乳液的破乳.     

破乳剂对复合驱乳状液的破乳机理研究

针对模拟采出液和三元复合驱矿场采出液,研究了破乳剂对复合体系界面张力和膜强度的影响.破乳剂浓度增加,二元复合体系界面张力降低,而三元复合体系界面张力升高.破乳剂分子部分顶替乳化剂分子并显著降低了界面膜强度.     

不同结构破乳剂油水界面扩张粘弹性研究

研究了支链破乳剂AE121和直链破乳剂SP169在正癸烷-水界面上的扩张粘弹性质,阐述了两种破乳剂扩张模量随扩张频率和破乳剂浓度的变化规律,考察了两种破乳剂对原油活性组分界面扩张性质的影响,测定了两种破乳剂的水溶液与正癸烷的动态界面张力,并与界面扩张流变性质进行了关联.研究结果表明,两种破乳剂的加入均会大大降低原油活性组分界面膜的扩张模量.较低浓度下直链破乳剂SP169由于吸附能力稍强,降低扩张模量效果较好；而一定浓度以上支链破乳剂AE121由于顶替能力较强,具有一定优势.由于破乳剂本身具有一定的扩张模量,在降低界面扩张模量的效果上,破乳剂的用量并非越大越好.     

水基纳米聚硅乳液的制备及增注性能研究

选用复配表面活性剂,用水代替柴油作为携带介质,将超疏水的纳米聚硅均匀稳定地分散在水中,制备成水基纳米聚硅乳液.室内试验结果表明:所制备的水基纳米聚硅乳液的分散性和稳定性较好,制备过程简单易行,便于实现工业化生产.粒径为10 nm左右的SiO2微粒在水中分散良好,该乳液遇盐发生破乳,释放出来的纳米聚硅微粒粒径在5～10 ...     

电极/反相微乳液体系电沉积制备纳米金镀层

将含有氯化金的强酸性水溶液作为水相与Triton X-100、正己醇、正己烷组成反相微乳液体系, 并以该微乳液构成电极/反相微乳液电极系统, 利用电沉积方法成功地制备出纳米Au镀层. 循环伏安和交流阻抗对反相微乳液体系电沉积过程的研究发现, 微乳液中Au(III)的还原为完全不可逆过程, 其电化学反应的阻抗值约为具有相同表观浓度氯化金水溶液体系的5.5倍. SEM研究结果表明, 利用微乳液体系电沉积获得的金镀层由纳米Au颗粒组成, 直径为50 nm左右. 所制备的纳米Au修饰电极由于具有较大的比表面积, 其电化学性能优于纯Au电极, 该电极在酸性条件下有较好的析氢性能, 在碱性条件对丙三醇有较好的电催化氧化性能.     

STATISTICAL MECHANICAL MODEL THEORY OF THE STABILITY OF O/W AND W/O MICROEMULSIONS

A theoretical model to clarify the molecular origin of the mechanical and thermal stabilities of O/W or W/O microemulsion is proposed in which the low concentration of surfactants (emulsifiers) is limited. We assume only a short range interaction between surfactants and a bending stiffness energy which expresses the deformation energy from a preferable monolayer membrane curvature. We have found an interrelation among the interfacial pressure, Δp, of the monolayer due to the adsorption of surfactants in the microemulsion interface, interfacial tensions of oil-water interface and of the microemulsion, and the bending stiffness energy. We conclude that the interfacial tension and the stable form of the microemulsions (O/W type or W/O type) are infuenced largely by the effect of the bending stiffness energy. The interrelationship between the therraodynamical and mechanical stabilities of microemulsions is clarified by the use of our assumption.     

A study of interfacial dilational properties of two different structure demulsifiers at oil-water interfaces

The interfacial dilational viscoelastic properties of two demulsifiers with straight chain (SP-169) and branched chain (AE-121) at the oil-water interfaces were investigated by means of the longitudinal waves method and the interfacial tension relaxation method, respectively. The results obtained by the longitudinal waves method showed that the dilational viscous component for AE-121 and SP-169 also passed through a maximum value with increasing concentration. It was found that the maximum value appeared at different demulsifier concentrations during our experiment frequency; and the higher is the dilational frequency, the lower is the concentration. The influences of AE-121 and SP-169 on the dilational viscoelastic properties of the oil-water interface containing surface-active fraction from Iranian crude oil have been measured. The results clearly stated that both demulsifiers could obviously decrease the dilational elasticity of oil-water interface containing surface-active fraction. At low concentration, because of stronger adsorption ability, SP-169 has stronger ability to decreasing the dilational modulus than AE-121. We also found that the dilational modulus of the interface contained surface-active fraction passed through a minimum value with increasing demulsifier concentration for both demulsifiers. This result indicated the dosage of demulsifier had an optimum value. The results obtained by means of interfacial tension relaxation method showed that the slow relaxation processes involve mainly rearrangement in the conformation of the molecules appeared with increasing demulsifier concentration.     

Effect of Demulsifier Structures on the Interfacial Dilational Properties of Oil–Water Films

The dilational properties of a branch-shaped polyether-type nonionic demulsifier (PEB), a comb-shaped polyether-type nonionic demulsifier (PEC), and a star-shaped polyether-type nonionic demulsifier (PES) at the decane–water interfaces were investigated by Langmuir trough method through oscillating barrier and interfacial tension relaxation methods, which are mainly in the influences of oscillating frequency and bulk concentration on dilational properties. Meanwhile, the effect of demulsifiers on interfacial dilational modulus of diluted crude oil was also explored. The experimental results indicate that all demulsifiers can decrease the dilational modulus of diluted crude oil at the experimental concentration. The addition of PEB causes the dilational modulus of crude oil to be lower than that at the water–decane interface. The demulsifier PEC has a similar effect with PES to influence the interfacial film of crude oil: at low concentration, the dilational modulus of mixed interfacial film is lower than that of demulsifier alone, while at high concentration, the dilational modulus of mixed interfacial film is slightly higher than that of demulsifier alone. The dependence of static modulus on the bulk concentration is consistent with the trend of interfacial dilational modulus with concentration for demulsifiers PEB, PEC, and PES. The studies about the structure modulus show that the new demulsifiers PEC and PES have a stronger ability than branch-shaped demulsifier PEB to destroy the interfacial film.     

Triacylglycerol microemulsions stabilized by alkyl ethoxylate surfactants--a basic study. Phase behavior, interfacial tension and microstructure

As triacylglycerols are the main components of natural fats and oils their solubilization in the form of emulsions or microemulsions was of great interest within the last years. However, systematic studies of their properties along the classical lines of complex fluids science are still missing. In the present paper we focus on the phase behavior, the interfacial tension and the microstructure of systems of type H(2)O/NaCl-triacylglycerol-alkylpolyglycolether (C(i)E(j)). The interfacial tension between water and oil sigma(ab) is high in a microemulsion system containing triolein. Thus, one needs high surfactant mass fractions to formulate a single-phase microemulsion. We show that this is not only true for triolein, but also for saturated long-chained triacylglycerols. The determination of the amphiphilicity factor f(a) and the calculation of the bending rigidities of the amphiphilic film confirm that despite the fact that high surfactant mass fractions and high temperatures are needed to solubilize triolein in a system of type H(2)O/NaCl-triacylglycerol-alkylpolyglycolether (C(i)E(j)), this is still a microemulsion in the narrower sense.     

The Application and Research of Dispersing In Situ Nano-SiO2 in Polyether Demulsifier TA1031

In order to enlarge the application range of nanomaterial and improve the demulsification performance of macromolecule polyether demulsifier, the nano-SiO₂ was dispersed in situ in polyether demulsifier TA1031 to form a new high efficiency demulsifier. The new demulsifier was analyzed by FTIR, SEM, rotational viscometer, and interfacial tension meter. The result showed that dispersing nano-SiO₂ in crude oil demulsifier would greatly improve the demulsification performance of the original demulsifier. When the ratio of silicon dioxide and TA1031 is 1:10 (mass ratio), the demulsification performance of the new demulsifier was the best, and the dehydration rate of emulsion increased about by 20%. Also the time of demulification and dehydration would be greatly shortened, and the demusification mechanism was preliminary analyzed.     

丙烯酰胺对Span80-Tween85/Isopar M/丙烯酰胺-H2O拟三元体系相行为的影响

考察了丙烯酰胺对水/IsoparM界面张力的影响以及对水溶液中非离子性乳化剂Tween85的助溶效果,并深入探讨了丙烯酰胺对Span80-Tween85/IsoparM/AM-H2O拟三元体系相行为的影响过程。结果表明,丙烯酰胺能够提高Tween85在水溶液中的溶解度,并可有效降低油水界面张力,进而能够扩大Span80-Tween85/IsoparM/AM-H2O拟三元相图的反相乳液区域面积。     

Solubilization and phase equilibria of water-in-oil microemulsions : II. Effects of alcohols, oils, and salinity on single-chain surfactant systems

The solubilization and phase equilibria of w/o microemulsions have been shown to be dependent on two phenomenological parameters, namely the spontaneous curvature and elasticity of the interfacial film, when interfacial tension is very low. The spontaneous curvature of an interface is basically determined by the geometric packing of surfactant and cosurfactant molecules at the interface, whereas the interfacial elasticity is related to the energy required to bend the interface. The droplet size and solubilization of microemulsions is mainly determined by the radius of spontaneous curvature, and is further influenced by interfacial elasticity and interdroplet interactions. A w/o microemulsion with a highly curved and relatively rigid interfacial film can exist in equilibrium with excess water at the solubilization limit due to the interfacial bending stress. Increasing the natural radius and fluidity of the interface can increase the droplet size and hence the solubilization in the microemulsion. On the other hand, a w/o microemulsion with a highly fluid interfacial film can exist in equilibrium with an excess oil phase containing a low density of microemulsion droplets due to attractive interdroplet interaction. Increasing the interfacial rigidity and decreasing the natural radius in this case can increase water solubilization in the microemulsion by retarding the phase separation process. Thus, a maximum water solubilization in a w/o microemulsion can be obtained by minimizing both the interfacial bending stress of rigid interfaces and the attractive interdroplet interaction of fluid interfaces at an optimal interfacial curvature and elasticity. The study of phase equilibria of microemulsions can serve as a simple method to evaluate the property of the interface and provide phenomenological guidance for the formulation of microemulsions with maximum solubilization capacity.     

Physical Properties of Microemulsions

Abstract

We have measured the interfacial tensions, vs. oil and brine, the electric conductivity and the magnetic susceptibility of microemulsions as a function of brine concentration and temperature.

The middle phase microemulsions exhibit the lowest interfacial tension, a sharp increase in the microemulsion/brine conductivity ratio and a maximum of the (diamagnetic) susceptibility.

The possibility of a percolative process and chemical or physical changes in the middle phase are discussed.     

Influence of demulsifier on interfacial film between oil and water

Demulsification of a synthetic water in oil (W/O) crude oil emulsion was studied by measuring water–oil interfacial properties such as life time and thinning rate of oil film in the presence of various demulsifiers. The results indicated that the interfacial elasticity decreased both the strength and the life time of oil film and film thickness when adding the demulsifiers. The oil film broke when film thickness came to a critical level. As for a demulsifier, the interfacial elasticity was decreased with demulsifier concentration increase, and stayed constant above a critical demulsifier concentration. The rate of dewatering is related to interfacial elasticity. When different demulsifiers were compared, the more the interfacial elasticity was lowered, the more efficient was the dewatering. The mechanism of the different types of demulsifiers was discussed based on the experimental results. The demulsifiers partially replaced the emulsifiers, which led to the interfacial elasticity decreased. The effect of chemical structure of the demulsifiers on water–oil interfacial film was studied.