CO2／[Bmim]Br-AICl3／苯体系相平衡研究

在温度40-80℃、压力1．50～1200MPa条件下,测定了CO2在氯铝酸离子液体（[Bmim]Br-AICl3）中的溶解度;在60℃以及3．00-10．00MPa条件下,测定了CO3／[Bmim]Br-AICl3／苯三元体系中气液相平衡数据,获得了三组分物系的相图。实验结果表明：在低压条件下,CO2在离子液体中的溶解度（XCO2）随压力增加而升高：当温度在40～80℃、压力9．00-10．00MPa范围内,XCO2分别达到最大值。在CO2／[Bmim]Br-AICl3苯三元体系中,根据各组分的最初摩尔比的不同,平衡体系中分别会出现气．液两相及气．液一液三相。压力对富苯相中各组分影响较富离子液体更大：在60℃,1O．00MPa条件下,体系中有颓相生成,气-液两相区转变为气-液-液三相区。     

CO_2-苯-长链烷基苯-[Bmim]Br-AlCl_3四元体系相平衡测定

利用静态分析法,在40℃、0.10~10.60MPa条件下考察了CO2-苯-1-十二烷基苯-[Bmim]Br-AlCl3、CO2-苯-1-十四烷基苯-[Bmim]Br-AlCl3、CO2-苯-1-十六烷基苯-[Bmim]Br-AlCl3三种四元体系的相态并测定了相平衡数据,比较了长链烷基苯的分配系数(长链烷基苯在底部液相中的质量分数与其在中间相中质量分数的比值)随压力变化的规律。结果表明:加入CO2促进了长链烷基苯在离子液体中的溶解。在40℃、8.10MPa条件下,CO2-苯-1-十二烷基苯-[Bmim]Br-AlCl3体系有新中间液相生成;随着长链烷基苯链长的增加,底部液相由液相逐渐转变为固相。在40℃、8.10MPa条件下,1-十二烷基苯、1-十四烷基苯的分配系数接近1.0;在40℃、4.00MPa条件下,1-十六烷基苯的分配系数接近1.0。     

CO2介质中离子液体催化苯与1-十二烯烃连续式反应

为了解决离子液体催化苯与长链烯烃连续式反应中离子液体相与反应液相互溶性差的问题,在[Bmim]Br-AlCl3催化苯与1-十二烯烃连续式反应中引入了CO2作为反应介质,并考察了CO2-苯-1-十二烷基苯-[Bmim]Br-AlCl3四元物系的相平衡和CO2压力、温度、空时和苯烯比对烷基化反应的影响。结果表明,在30-60℃,7．90-8．10MPa的条件下,反应物在离子液体相与反应液相浓度分布均一,有利于提高烯烃的转化率。提高苯烯比对改善单取代烷基苯产率的作用明显。在60℃,8．10MPa和空时为2min的条件下,苯烯物质的量之比为2时,单取代十二烷基苯产率最高为59．2％,苯烯物质的量之比为12时,单取代烷基苯的产率为85．9％。     

CO2-苯-长链烷基苯-[Bmim]Br-AICl3四元体系相平衡测定

利用静态分析法,在40℃、0．10—10．60MPa条件下考察了CO2-苯-1-十二烷基苯-[Bmim]Br-A1Cl3、CO2-苯-1-十四烷基苯-[Bmim]Br—AICl3、CO2-苯-1-十六烷基苯-[Bmim]Br—AICl3三种四元体系的相态并测定了相平衡数据,比较了长链烷基苯的分配系数（长链烷基苯在底部液相中的质量分数与其在中间相中质量分数的比值）随压力变化的规律。结果表明：加入CO2促进了长链烷基苯在离子液体中的溶解。在40℃、8．10MPa条件下,CO2-苯-1-十二烷基苯-[Bmim]Br—AICl3体系有新中间液相生成;随着长链烷基苯链长的增加,底部液相由液相逐渐转变为固相。在40℃、8．10MPa条件下,1-十二烷基苯、1-十四烷基苯的分配系数接近1．0;在40℃、4．00MPa条件下,1-十六烷基苯的分配系数接近1．0。     

微通道中气体/离子液体两相流动与分散性能

离子液体在气-液反应与分离过程中有良好的应用前景,研究气体/离子液体两相体系的微分散过程对于发展新型气-液分散技术和设备具有重要意义。研究了N₂/[Bmim]BF₄体系在同轴环管微通道中的流动和分散行为。实验结果表明,在不同的气相和液相流速下,N₂/[Bmim]BF₄体系分别呈现气泡流、气泡-气柱过渡流、气柱流和气柱-环隙流过渡流4种流型。通过考察分散相尖端尺寸和气相、液相流速对气-液体系流型的影响,作出了相应的流型图。通过考察气相、液相流速对稳定气-液分散流型下的气相分散尺寸的影响,揭示了分散气相行为的机理,并建立了描述气相分散尺寸的数学模型。     

离子液体水溶液-气体水合物对CO2的双捕获工艺

设计了以离子液体[APMIM]Br水溶液吸收-生成水合物捕获CO2工艺流程,并利用CO2在该离子水溶液中的溶解度数据和在其中生成CO2水合物的相平衡实验数据进行物料衡算. 考察了水含量、压力和液气流量比对气体吸收-水合物生成的CO2双重捕获效果的影响,对比了气体水合物与离子液体水溶液捕获CO2的能力. 结果表明,在较高压力和水含量条件下,水合物捕获CO2的效应强于离子液体溶液;较低压力下离子液体溶液吸收CO2起主要作用. 与纯水合物法相比,双捕获工艺具有一定优势,且突破了单纯水合物脱碳的压力和CO2含量要求高的局限性. 当原料气中CO2低于65%(j)时,系统的脱碳效率低于40%,对于CO2含量较低的气体,其CO2的脱除性能回归至单纯离子液体溶液体系.     

H2O-CH2Cl2-[Bmim]BF4体系的液液相平衡测定及其关联

采用两步法合成了离子液体[Bmim]BF4,并利用红外光谱、核磁共振、元素分析等手段对所合成的产物进行表征和分析。利用浊点法测定了常压30℃下H2O-CH2Cl2-[Bmim]BF4体系的饱和溶解度曲线和密度曲线并进行了关联,还进一步采用浊点-密度法测定该体系的液液相平衡数据。由实验数结果可以看出:该体系上相以H2O为主,CH2Cl2、[Bmim]BF4的含量很少,下相则以[Bmim]BF4、CH2Cl2为主,H2O的含量很少;随着体系中CH2Cl2含量的增加上相中[Bmim]BF4的含量从0.1665下降到0.1032。由此可见在纯化离子液体[Bmim]BF4时适当地增加CH2Cl2的用量可以减少[Bmim]BF4的损失。采用Othmer-Tobias和Bancroft经验方程对液液相平衡数据进行关联,关联结果不理想;采用Othmer-Tobias经验方程+溶解度方程法对其关联,最大相对误差为4.43%,最大平均相对误差为3.03%,关联精度较高。     

[Bmim]Cl-xAlCl_3催化合成十二烷基苯

采用AlCl3和[Bmim]Cl不同摩尔比的[Bmim]C1-xA1C13离子液体为催化剂,研究了不同条件下1-十二烯与苯的烷基化反应。实验结果表明,以A1Cl3和[Bmim]Cl的摩尔比为2.0([Bmim]Cl-2A1C13)的离子液体为催化剂,在反应温度25℃、反应时间30 min,苯、烯及离子液体的摩尔比为5︰1︰0.03的条件下,正十二烯的转化率可达98.32%,2-LAB的选择性可达36.76%。离子液体和产物可形成易于分离的双液相,简化了催化剂与产物的分离操作。     

[Bmim][PF6]高效吸收二氯甲烷及流程模拟

采用智能重量吸附仪测量了不同温度、压力下二氯甲烷(CH2Cl2)在离子液体1-丁基-3-甲基咪唑六氟磷酸盐([Bmim][PF6])中的溶解度,用NRTL方程建立了离子液体?二氯甲烷体系的气液平衡模型,拟合得到二元交互作用参数,计算所得的二氯甲烷溶解度与实验数据吻合良好,平均相对误差为3.16%. 构建了离子液体处理含二氯甲烷尾气及资源回收利用的常压吸收?减压闪蒸解吸工艺和模型,模型适用范围为温度278.15~308.15 K,压力0~0.1 MPa. 对吸收塔进行了模拟和灵敏度分析,获得了常温常压吸收条件下的最佳操作工艺参数.     

H2O-[Bmim]BF4-Na2CO3离子液体双水相体系的神经网络模型研究

基于BP（Back-Propagation）神经网络模型,编写了通用的计算程序,对30℃时H2O-[Bmim]BF4-Na2CO3离子液体双水相体系的液液平衡数据进行了关联,经过反复试算,得到最佳的神经网络拓扑结构为{3,10,3},采用该结构关联富含水相中三种组分的质量分数,平均相对误差分别为0.065%、2.218%和0.781%,最大相对误差为3.916%;优于文献中的Othmer-Tobias经验方程＋溶解度曲线方程的关联精度,该方程得到的平均相对误差分别为0.09%、2.77%和1.73%,最大相对误差为4.52%。较为成功地应用神经网络模型处理了含离子液体的双水相体系的液液平衡数据。     

Compact Swelling in Bi1.4Pb0.6Sr2Ca2Cu3.6Oy During the Formation of High-Tc Superconducting Phase

Compact swelling in Pb-doped Bi-Sr-Ca-Cu-O superconductor has been studied by observing the effects of the size of calcined powders, volatilization of materials, and sintering of high- T _c (2223) powders. The bulk density increases at the early stage of sintering, for about 20 h, and then decreases. Densification occurs when the low- T _c (2212) phase and a liquid phase exist, whereas dedensification occurs with the formation of the 2223 phase regardless of the presence of the liquid. Gas evolution from specimens does not appear to be responsible for compact swelling. Compact swelling is explained by anisotropic growth of thin, platelike 2223 grains in random orientation. When 2223 grains grow in a preferred direction, compact swelling is suppressed.     

Synthetic routes to nanoscale BxCyNz architectures

B_xC_yN_z nanoscale materials, hybrids of h-BN and graphite, have been recently synthesised using various techniques. Here, we present the latest advances in the synthesis and characterisation of B-C-N nanotubes and nanofibres. In particular, we focus on layered BC₂N, BN, BC and CN_x systems, reviewing their production methods as well as their structural and electronic properties. These materials may find important applications in the fabrication of nanotransistors, robust nanocomposites, conducting polymers, storage components and field emission sources.     

Microwave Dielectric Properties of CaTiO3-CaAl1/2Nb1/2O3 Ceramics Doped with Li3NbO4

The microwave dielectric properties of CaTi_{1− x} (Al_1/2Nb_1/2) _x O₃ solid solutions (0.3 ≤ x ≤ 0.7) have been investigated. The sintered samples had perovskite structures similar to CaTiO₃. The substitution of Ti⁴⁺ by Al³⁺/Nb⁵⁺ improved the quality factor Q of the sintered specimens. A small addition of Li₃NbO₄ (about 1 wt%) was found to be very effective for lowering sintering temperature of ceramics from 1450–1500° to 1300°C. The composition with x = 0.5 sintered at 1300°C for 5 h revealed excellent dielectric properties, namely, a dielectric constant (ɛ_r) of 48, a Q × f value of 32 100 GHz, and a temperature coefficient of the resonant frequency (τ_f) of −2 ppm/K. Li₃NbO₄ as a sintering additive had no harmful influence on τ_f of ceramics.     

Preparation and properties of poly(Nε,Nε-dicarboxymethyl-l-lysine)

A new ampholytic homopolypeptide, $\text{poly}\text{(N}{}^{\mathrm{\epsilon }}\text{,N}{}^{\mathrm{\epsilon }}\text{-}\text{dicarboxy-methyl-}\text{l}\text{-lysine}\text{)}$, which has one tertiary amino and two carboxyl groups in the side chain has been derived from a hydrochloride salt of poly(L-lysine). The polymer in aqueous solution seems to be in the coil form with locally extended structure (LES) at neutral pH. In both the acidic and alkaline regions, the molar ellipticity of the polymer changes as a result of change in net charge on the side chain. The conformational changes may be from the coil with LES to other coiled forms. 5–7 M NaClO₄ and 80% aqueous methanol induce the α-helix in the polymer at neutral pH. Divalent cations, Cu²⁺ and Ca²⁺, do not induce any remarkably ordered structures such as α-helix or β-structure in the polymer in aqueous solution at any pH. Ultraviolet absorption studies show an absorption peak of the polymer-Cu²⁺ complex near 240 nm. Dependence of the peak intensity on pH at various q values ($\text{q =}\text{[}\text{Cu}{}^{\mathrm{2+}}\text{]}\text{[}\text{residue}\text{]}$) indicates the two steps of the complex formation. At q less than 0.64, the formation is described only with the first step. An average coordination number for Cu²⁺ at the first step was calculated to be about 2 by the method of Mandel and Leyte. The association constant of Cu²⁺ with the residue at the step was determined from the absorption data to be far smaller than that for the Cu²⁺-EDTA complex. The second step of the formation occurs in the case of large q but the absorption data for the second step cannot be obtained exactly due to precipitation.     

Structure Evolution from Pb(Mg1/3Nb2/3)O3 to La(Mg2/3Nb1/3)O3

The crystal structure of lanthanum-modified lead magnesium niobates having composition (Pb_{1− x} La _x ) (Mg_{(1+ x )/3}-Nb_{(2− x )/3})O₃ with X = 0 to 1 was investigated by X-ray powder diffraction. It was found that the fundamental reflections from perovskite structure remain in the whole range of composition. The superlattice reflections from the A(B'_1/2-B"_1/2)O₃ ordered structure are also well preserved for La content greater than 50 at.%; however, a series of extra peaks of mixing indices appears, with intensities gradually enhanced with the increase of La content. For the complete substitution of Pb by La, a splitting of some reflections can be observed in the diffraction pattern. The results indicate that the crystal structure evolves continuously with the La content, from disordered cubic perovskite of space group Pm 3 m for X = 0, to ordered cubic perovskite of space group Fm 3 m for X = 0.5, distorted cubic perovskite of space group Pa 3 for 0.5 < X < 0.9, and finally to a rhombohedral perovskite, possibly belonging to the space group R 3 , for X ≥ 0.9. In the evolution of structure, a linear reduction of the lattice constant of the perovskite cell from 4.048 to 3.964 Å was observed.     

Dielectric-State Analysis in Solid-Solution Pb(Yb1/2Ta1/2)O3–Pb(Lu1/2Nb1/2)O3

The structure and temperature dependence of complex lead perovskite dielectrics were investigated for the system (1 − x )Pb(Yb_1/2Ta_1/2)O₃– x Pb(Lu_1/2Nb_1/2)O₃. Superlattice reflections for the compositions 0.8 < x < 1.0 were observed by X-ray diffractometry, and the temperature-composition dielectric-state diagram was determined. In the present study, the disordered middle composition, with 0.2 < x < 0.8, showed a diffuse paraelectric–ferroelectric phase transition, whereas the ordered end compositions, with 0 ≤ x < 0.2 and 0.8 < x ≤ 1.0, revealed successive sharp paraelectric–antiferroelectric and weak antiferroelectric–ferroelectric phase transitions. The dielectric state was confirmed by examining the variation of polarization ( P ) with electric field ( E ).