含醇体系超额性质模型TDAM的导出和应用

本文针对含醇体系的特性,基于缔合溶液理论,导出了一个形式简单、物理意义明确的溶液模型——TDAM.由于TDAM模型中引入了较为合理的温度关系,仅需两套不同温度下的超额焓数据,即可进行其它温度下超额焓数据以及汽液平衡数据的推算.将TDAM模型对非极性、极性体系超额焓的关联结果与其它常见溶液模型(Wilson、W-C和QCSM等)进行了比较,以TDAM模型为最佳;对含醇体系汽液平衡数据也进行了同样的比较,TDAM模型关联结果优于或相当于其它溶液模型.将该模型用于超额焓和汽液平衡的推算,结果令人满意.     

α-蒎烯-蒎烷-长叶烯体系汽液平衡及其过量Gibbs自由能与超额焓

采用改进Ellis平衡釜测定了α-蒎烯-蒎烷、α-蒎烯-长叶烯、蒎烷-长叶烯三个二元体系及α-蒎烯-蒎烷-长叶烯三元体系常压汽液平衡数据,经Herington规则检验符合热力学一致性。由汽液平衡数据求出每个二元体系中各组分的活度系数,再关联得到相应的过量Gibbs自由能与超额焓实验值。结果表明,α-蒎烯-蒎烷体系的Gibbs自由能对理想溶液呈现较小的正偏差,而α-蒎烯―长叶烯和蒎烷-长叶烯体系Gibbs自由能对理想溶液呈现负偏差。根据Wilson方程对三个二元体系的过量Gibbs自由能和超额焓进行了计算,关联值与实验值吻合,对α-蒎烯-蒎烷体系最大超额焓为120.48 J×mol~(-1),α-蒎烯―长叶烯体系最大超额焓为401.09 J×mol~(-1),蒎烷-长叶烯体系最大超额焓为685.75J×mol~(-1)。由关联得到的二元体系能量参数推算了α-蒎烯-蒎烷—长叶烯三元体系的过量Gibbs自由能和超额焓,过量Gibbs自由能的实验值与计算值基本吻合,平均相对偏差为1.7147%,该三元体系的最大超额焓为627.16 J×mol~(-1)。     

β-石竹烯、对伞花烃及3-蒈烯二元体系的超额焓

利用C80型Calvet微量量热仪测定了对伞花烃+β-石竹烯,3-蒈烯+β-石竹烯和3-蒈烯+对伞花烃三个二元体系在298.15 K下的超额焓。三个二元体系的超额焓数据在全浓度范围内均为正值,并且最大值均在摩尔分数x1=0.5附近。采用Redlich-Kister方程对实验数据进行关联,标准偏差分别为0.2151、0.1773和0.4483 J·mol~(-1)。结果表明实验所测定的超额焓与关联结果吻合较好。在相同温度下,3-蒈烯+对伞花烃体系的超额焓值均大于含重质松节油组分的对伞花烃+β-石竹烯和3-蒈烯+β-石竹烯体系。     

用FRKS状态方程关联高度非对称二元系超额焓

引言对于组分分子大小、形状、结构相差较大的高度非对称混合物,迄今仍未有计算其超额焓的满意的方法．最近Lin等用转子链立方状态方程计算了高度非对称二元系的超额焓．在他们的工作中,使用两个可调参数虽然明显改进了计算,但对大多数体系,误差仍较大．对于这一类体系,立方状态方程失败的两个主要原因是：一、对于纯物质,立方状态方程中的引力参数α通常表为温度T和偏心因子ω的函数．对于复杂化合物,特别是长链碳氢化合物,由于其性质偏离正常流体较远,偏心因子已不可靠,另外,对于高沸点物质,也难以得到可靠的ω数值;因此,…     

氢化松节油体系过量Gibbs自由能及超额焓

利用α-蒎烯-β-蒎烯、α-蒎烯-蒎烷二元体系常压汽液平衡数据,研究氢化松节油体系过量G ibbs自由能及超额焓的关联与计算。由汽液平衡数据求出体系中各组分的活度系数,从而关联得到相应的常压过量G ibbs自由能实验值,结果表明,α-蒎烯-β-蒎烯、α-蒎烯-蒎烷体系对理想溶液呈现较小的正偏差。根据W ilson方程对α-蒎烯-β-蒎烯、α-蒎烯-蒎烷体系的常压过量G ibbs自由能和超额焓进行了计算,计算值与实验值吻合良好,对α-蒎烯-β-蒎烯体系最大超额焓为12.663 1 J/mol,α-蒎烯-蒎烷体系最大超额焓为126.783 7 J/mol。     

甲酰胺+乙醇/丙醇/异丙醇/乙酸乙酯二元混合物的体积及黏度性质

为理解含甲酰胺二元溶液的超额性质变化及分子间相互作用,常压下测定了甲酰胺(FA)分别与乙醇、丙醇、异丙醇和乙酸乙酯组成的二元系在293.15~318.15 K的密度和黏度,计算了超额摩尔体积(VE)和黏度偏差(Δη)。采用半经验的黏度方程对实验黏度数据进行了关联和预测,并基于Eyring绝对速率理论方法计算了黏滞性活化参数。结果表明,四个二元系的超额摩尔体积均为负值,且都随温度升高而偏差增大。FA-乙醇和FA-乙酸乙酯两个体系的黏度偏差为负值,且随温度降低而偏差增大。FA-丙醇和FA-异丙醇两个体系的黏度偏差随FA组分增加呈‘S’形变化,在甲酰胺低浓度区由负值变为正值,也均随温度降低而偏差增大。Mc Allister模型对黏度数据的关联结果最好,预测值与实验值的平均相对偏差最小。黏滞性活化参数说明混合过程中焓驱动起主导作用。     

水-丙酸二元体系汽液平衡的热力学性质

用新型泵式沸点仪测定了在101.325kPa下水-丙酸二元系在不同液相组成时的沸点,用过量自由焓函数Q,采用间接法由Tpx推算了水-丙酸二元系的汽相平衡组成y。汽相的非理想性用截至第二项的维里系数的状态方程求出汽相混合物中组分逸度系数。二元体系活度系数的关联分别用Wilson模型、NRTL模型、Margules模型和vanLaar模型进行关联,用最小二乘法求出了它们的液相活度系数模型参数。用所得的液相活度系数来计算三个二元体系的过量吉布斯自由焓函数GE/RT。计算的泡点温度与实验测得的沸点温度吻合良好,由面积积分法检验这些模型参数计算的二元体系相平衡数据,得到很好的热力学一致性。     

CO_2-[emim][Tf_2N]二元体系汽液相平衡及超额焓研究

针对CO_2-离子液体二元体系的相平衡问题,搭建了一套汽液相平衡数据测定系统,获得了CO_2-[emim][Tf_2N]二元体系在273.15～328.15 K的汽液相平衡数据,利用PR (Peng-Robinson)状态方程、NRTL (non-random two liquid)活度系数模型结合WS (Wong-Sandler)混合规则对实验数据进行关联,并应用此模型计算得到CO_2-[emim][Tf_2N]二元体系的超额焓。结果表明:关联得到的压力计算值与实验值相比,两者的平均相对偏差为3.87%,与其他模型对比所选模型偏差最小,能够成功地关联CO_2-[emim][Tf_2N]二元体系汽液相平衡数据。进一步完善了CO_2-离子液体二元体系的关联模型。     

N,N-二甲基甲酰胺、正丙醇、异丙醇的二元及三元系等组成汽液平衡

引　言近年来 ,随着生命科学和分子热力学的发展 ,生化模型分子 (例如含Ｎ ,Ｎ -二甲基甲酰胺 (ＤＭＦ)和醇的混合物 )由于其在生化过程模拟中的重要意义 ,正引起人们越来越多的注意 .它们的一些热力学性质 (如过量体积、过量焓等 )已经有所报道[1～ 3 ] .为了更深入地了解这些体系中分子间的作用力 ,本文进行了ＤＭＦ +正丙醇 +异丙醇体系及相关二元组分体系的等组成汽液平衡 (ＶＬＥ)研究 .将 3种二元混合物的汽液平衡数据用修正过的带温度相关二元参数的ＵＮＩＱＵＡＣ方程进行了关联 ,然后与文献值进行比较 :ＤＭＦ +异丙醇 ,Ｔ =35 3 1…     

含极性组分体系的超额焓

提出了一种改进的Flory模型,将Flory溶液模型的相互作用参数x_(12)表达成体系组成的函数,并改进了纯物质参数的确定方法。由改进后的Flory溶液模型导出的超额焓方程能用于含水、醇、酮和羧酸等强极性物质体系的超额焓计算。计算结果比改进前的Flory模型、Wilson模型和NRTL模型都好。     

Estimation of excess enthalpy for binary systems

Based on the author’s molecular thermodynamic model for solution structure, a new equation with three parameters for correlating the excess enthalpy of binary solutions is proposed. We make use of the group statistical theory, Lagrange undetermined multiplier method and a pseudo-chemical reaction mechanism. Tested by 6059 experimental data in 282 kinds of binary systems, the new model shows the characteristics of convenience and wide applicability. The accuracy of the new equation has an advantage over the Redlich–Kister equation [J. Chem. Ind. Eng. (China) 49 (1998) 103] and the Shen–Liu equation proposed recently [J. Chem. Ind. Eng. (China) 51 (2000) 181], both of which have three parameters too. As for the SSF equation with four parameters, the accuracy of it and the new equation is equivallent, some times the latter is more accurate. The new equation is still tenable in the limiting condition of x→0 and 1.     

含醇二元物系过量焓的测定与缔合对过量焓的影响

用Calvet微量热仪测定了正辛烷—正辛醇、正辛烷—正庚醇、正辛烷-异丙醇及正壬烷-仲丁醇、正壬烷-异丙醇五个二元物系在297.95K、常压下的过量焓H~E数据.用纠正后的QCSM缔合溶液模型对烃-醇物系氢键缔合对过量焓的影响进行了研究.对AGSM基团贡献模型进行了改进,引入了一个“修正参数”.修正后的AGSM模型对短分子链的醇与烷烃的过量焓的预测结果有明显的改善.     

Correlation of measured excess enthalpies of binary systems composed of n-alkane+1-alkanol

The excess enthalpies of the binary mixture composed of n-alkane (n-octane, n-nonane, n-decane) and 1-alkanol (ethanol, 1-propanol, 1-butanol) have been measured by using a flow-type isothermal microcalorimeter (model CSC 4400, Calorimetry Science Corp., USA) at 313.15 K under atmospheric pressure. The measured excess enthalpy data were correlated by the Redlich-Kister equation and the nonrandom lattice fluid with hydrogen bonding (NLFHB) equation of state. Hydrogen bonding type specific parameters were introduced in the NLF-HB equation of state framework, and the effects of those parameters were investigated for excess enthalpy calculations. With two adjustable temperature-dependent interaction parameters, the NLF-HB equation represents the excess enthalpies for nine binary systems qualitatively. This article is dedicated to Professor Chul Soo Lee in commemoration of his retirement from Department of Chemical and Biological Engineering of Korea University.     

EXCESS ENTHALPIES OF 3-METH YLPHENOL - n - HEPTANE, 3-METH YLPHENOL - PHENOL -n- HEPTANE AND 3-METHYLPHENOL- 1-HEXANOL-n-HEPTANE AT 318·15 K

Excess molar enthalpies H^E for two ternary systems, 3-methylphenol-phenol-n-heptane and 3-melhylphenol-1-hexanol-n-heptane and a constituent binary 3-methylphenol-n-heptane have been measured with Calvet-type microcalorimeter at 318·15 K. For predicting ternary excess enthalpies, the modified Redlich-Kister equation was used. It has been shown that the second ternary system exhibits regions of both exothermic and endothermic mixing, and due to the intricated interaction between phenols and alcohols predicting of ternary excess enthalpies with the Redlich-Kister equation is unsuccessful.     

Modeling infinite dilution activity coefficients of organic-aqueous systems using a modified regular solution equation and cubic equations-of-state

Expressions derived from the regular solution equation and the generalized cubic equations-of-state (EOS) were employed to model the infinite dilute activity coefficient (γ^∞) of organic-aqueous systems. A database of 119 organic species in aqueous systems, divided into six classes, was gathered for models evaluations. The use of the molar density, the first order molecular connectivity, and the dipole moment appear to be adequate correlating variables for describing the structural dependence of the residual part in the modified regular solution equation (MRS). The Soave-Redlich-Kwong (SRK) and Peng-Robinson (PR) were specified and employed in the generalized cubic EOS form. The excess activity coefficient concept was used in the SRK and PR EOS models to account for the deficiency of EOS in dealing with highly non-ideal or polar systems. The abilities of two existing correlation models along with two modified versions of the UNIFAC model were also assessed. The proposed models provide creditable equations for correlating γ^∞ of organic-aqueous systems.     

Measurement and correlation of excess enthalpies for water+ethanol+1-buthyl 3-methylimidaozolium tetrafluoroborate system

It is difficult to find physical properties data for systems containing ionic liquids, excess molar enthalpies, binary interaction parameter, etc. In this study, the excess molar enthalpies were measured for water+ethanol+ionic liquid system using a isothermal microcalorimeter at 298.15 K. The ionic liquid used was 1-butyl 3-methyl imidazolium tetrafluoroborate, [BMIM] [BF₄]. The isothermal microcalorimeter (IMC) is a flow-type calorimeter that measures the heat of mixing directly, using specific mixing cell. By employing NRTL, electrolyte-NRTL and UNIQUAC models, binary interaction parameters were determined and investigated for the correlation with vapor liquid equilibrium (VLE). The e-NRTL model with the partial dissociation was employed to correlate the ionic liquid system. The binary data of VLE system were used from literatures. Specifically, UNIQUAC volume and surface area parameters were determined using Bondi radius.     

1-丁基-3-甲基咪唑磷酸二丁酯+甲醇/乙醇+水三元工质溶液混合焓的测量及预测

采用绝热量热法测量了由离子液体1-丁基-3-甲基咪唑磷酸二丁酯([bmim][DBP])分别与CH₃OH、C₂H₅OH和H₂O所组成的3个二元工质溶液体系[bmim][DBP](1)+ CH₃OH(2)/C₂H₅OH(2)/H₂O(2),以及2个三元工质溶液体系[bmim][DBP](1)+ CH₃OH(2)/C₂H₅OH(2)+ H₂O(3)在298.15 K和常压下的摩尔混合焓H_m^E。利用Gibbs-Helmholtz方程和NRTL活度系数模型,对每个二元溶液体系摩尔混合焓的实验数据进行关联,获得模型方程中的组分作用参数。摩尔混合焓的模型拟合值与实验值的平均相对偏差分别为1.81%、1.44%和0.72%。在此基础上预测了2个三元工质溶液体系的摩尔混合焓。结果表明:三元工质溶液体系的摩尔混合焓在实验浓度范围内均为负值,混合为放热过程。表明三元工质溶液具有成为吸收制冷循环新工质溶液的基本特征;采用NRTL模型预测2个三元溶液体系摩尔混合焓的计算值与实验值的平均相对误差分别为2.31%、2.49%。     

一种半经验的关联-预测活度系数的系统

提出一种半经验的关联-预测活度系数的系统.二元系的活度系数用—过量自由焓模型推算.该模型的模型参数从2个代数方程联立求解,其一关联模型参数与γ~∞,另一关联模型参数与(dγ/dx)_x=0.γ~∞用MOSCED模型由纯组分性质关联.(dγ/dx)x=0用三维溶解度参数关联.用该系统对145组等温极性二元系作了预测,对计算结果与实验值作了对比.     

用MH-81′状态方程模拟液氮洗涤塔

本文采用MH-81′状态方程和与密度无关的局部组成型混合法则,从二元汽-液平衡数据得到的二元相互作用参数,预测了部分液氮洗过程中的二元体系的混合焓,结果满意。采用三对角矩阵方法,对两种不同工况的液氮洗涤塔进行了模拟,计算结果与设计值和实测值符合较好。