Isobaric Vapor-Liquid Equilibrium data for Binary Mixtures of n-butylamine and Triethylamine with Cumene at 97.3 kpa

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1 International Journal of Chemial and Biologial Engineering 3:3 1 Isobari Vapor-Liquid Equilibrium data for Binary Mixtures of n-butylamine and Triethylamine with Cumene at 97.3 kpa Baljinder K. Gill, V. K. Rattan, and Seema Kapoor 1 Abstrat Isobari vapor-liquid equilibrium measurements are reported for the binary mixtures of n-butylamine and Triethylamine with Cumene at 97.3 kpa. The measurements have been performed using a vapor reirulating type (modified Othmer's) equilibrium still. The binary mixture of n-butylamine + Cumene shows positive deviation from ideality. Triethylamine + Cumene mixture shows negligible deviation from ideality. None of the systems form an azeotrope. The ativity oeffiients have been alulated taking into onsideration the vapor phase nonideality. The data satisfy the thermodynami onsisteny test of Herington. The ativity oeffiients have been satisfatorily orrelated by means of the Margules, NRTL, and Blak equations. The ativity oeffiient values obtained by the UNIFAC model are also reported. Keywords Binary mixture, Cumene, n-butylamine, Triethylamine, Vapor-liquid equilibrium. I. INTRODUCTION EPARATION of liquid mixtures by distillation is one of Sthe most important proesses in hemial industries. For the design of distillation olumns, knowledge of vaporliquid equilibrium data is of utmost importane. Due to omplex vapor-liquid equilibrium problems arising from numerous new industrial proesses, there is a need for the aurate vapor-liquid equilibrium determinations experimentally. In addition to this, experimental data are required to update and improve the data bank used to fit the model parameters of various theoretial models. Very limited work has been reported on vapor-liquid equilibrium study of binary mixtures ontaining umene as one of the omponents. Isobari vapor-liquid equilibrium data for binary mixtures of N-Methylaetamide and N,N-Dimethylaetamide with Cumene has been studied and reported in [1]. In the present work, experimental vapor-liquid equilibrium data for binary mixtures of n-butylamine and Triethylamine with umene are reported. The measurements were performed under isobari onditions at a pressure of 97.3 kpa using a modified version of the reirulating type equilibrium still that has been Baljinder K. Gill is with the Department of Chemial Engineering, Beant College of Engineering and Tehnology, Gurdaspur-14351, India (orresponding author; phone: ; fax: ; e- mail: bkg-7@hotmail.om) Dr. V. K. Rattan is with the Univ. Institute of Chemial Engineering & Tehnology, Panjab University, Chandigarh-1614, India ( vkrattan@pu.a.in). Dr.Seema Kapoor is with the Univ. Institute of Chemial Engineering & Tehnology, Panjab University, Chandigarh-1614, India ( seemakap_4@sify.om). desribed earlier [], [3]. The binary system n-butylamine + Cumene has a wide boiling range i.e. 75 K and the other binary system Triethylamine + Cumene has a boiling range of 6.6 K. None of the systems form an azeotrope. The ompounds studied have a wide range of appliations and are of great industrial importane. Cumene is used to manufature other hemials suh as phenol, aetone, aetophenone, and methyl styrene. It is used as a thinner in paints, laquers, and enamels. Also, it is a omponent of highotane motor fuels. Natural soures of isopropylbenzene inlude rude petroleum and oal tar. n-butylamine is used as an intermediate in the synthesis of dyes, drugs, rubber additives, emulsifiers, tanning agents and insetiides. It is also used as a vulanizing aelerator for rubber and as a uring agent for polymers. Triethylamine is ommonly employed in organi synthesis as a base, most often in the preparation of esters and amides with ayl hlorides. It is also used in the synthesis of pestiides, pharmaeutials, paints and oatings. Other appliations of Triethylamine inlude uring, hardening and orrosion inhibition for polymers and its use as a propellant. II. EXPERIMENTAL Chemials: n-butylamine and Triethylamine were obtained from C.D.H (P) Ltd., India and Cumene was obtained from Merk-Shuhardt, Germany. All hemials were AR grade materials and had purities (by hromatographi analysis, as given by the manufaturer in area perent) of 98. %, 99. % and 99. % respetively. The hemials were purified using standard proedures [4] and stored over moleular sieves. The purity of the hemials was heked by measuring the refrative indies for the pure ompounds and omparing them with the values reported in the literature. The results are listed in Table I. Apparatus and Proedure: The vapor-liquid equilibrium data were obtained by using a modified version of the equilibrium still. The equilibrated mixtures were analyzed using a Baush and Lomb Abbe-3L refratometer. The apparatus, modifiations, and analytial tehniques have already been desribed earlier [5]. All the measurements were made at a onstant temperature with the help of a irulating-type ryostat (type MK7, MLW, Germany) maintained at a temperature within ±. K. The estimated unertainties in the measurements of mole fration were ±., in refrative index were ±., and in temperature were ±. K. 14

2 International Journal of Chemial and Biologial Engineering 3:3 1 III. RESULTS AND DISCUSSION The liquid-phase ativity oeffiients ( ) were alulated from the experimental data using the equations [6] below, whih take into aount the vapor phase nonideality: 1 ( P y1 / P1 )exp[{( B11 V1 )( P P1 )/ RT} ( P1y )/ RT] (1) ( Py / P x)exp[{( B V )( PP )/ RT} ( P1y1 )/ RT] () 1 B 1 B 11 B (3) where x 1, x and y 1, y are the equilibrium mole frations of omponents 1 and in the liquid and vapor phases, respetively; T and P are the boiling point and the total pressure; V 1 and V are the molar liquid volumes; B 11 and B are the seond virial oeffiients of the pure omponents; and B 1 is the ross seond virial oeffiient. Table II gives the physial onstants of the pure omponents. The pure omponent vapor pressures ( P ) were alulated aording to the Antoine equation: Log ( P /.133 ) A B /( C T 73.15) (4) The Antoine s onstants A, B, and C are reported along with physial onstants of pure omponents in Table II. The experimental vapor-liquid equilibrium data ( T, x 1, and y 1 ) at 97.3 kpa along with the alulated ativity oeffiients for n-butylamine + Cumene are presented in Table III and for Triethylamine + Cumene are presented in Table IV. The Yen and Woods [7] method was used for the estimation of liquid molar volumes. The Pitzer and Curl equation modified by Tsonopoulos [8] was used in the evaluation of seond virial oeffiient as well as ross virial oeffiients in this work. The data for the systems were assessed for thermodynami onsisteny by applying the Herington area test [9]. It shows that the experimental data are thermodynamially onsistent. The ativity oeffiients were orrelated with Margules, NRTL [1], and Blak equations. The adjustable parameter α 1 for the NRTL orrelation equation was set equal to.4 for the n-butylamine + Cumene system and was set equal to.41 for the Triethylamine + Cumene system. The estimation of parameters for the three orrelation equations is based on minimization of ln( 1 / ) as an objetive funtion using the nonlinear least square method of Nagahama, Suzuki, and Hirata as used by Rattan et al [11]. The orrelation parameters A 1, A, A and deviation in vapor phase omposition for 3 the n-butylamine + Cumene system and the Triethylamine + Cumene system are listed in Table V and Table VI respetively. The Blak equation gave the best fit with.375 as the average absolute deviation in the vapor phase omposition of n-butylamine for the n-butylamine + Cumene system. The Margules equation gave the best fit with.359 as the average absolute deviation in the vapor phase omposition of triethylamine for the Triethylamine + Cumene system. TABLE I REFRACTIVE INDEX, nd AT K n D Compound Exptl. Lit. n-butylamine [4] Triethylaminee [4] Cumene [4] TABLE II PHYSICAL CONSTANTS OF THE PURE COMPOUNDS Constant n-butylamine Triethylamine Cumene Moleular wt [1] [1] 1. [1] Boiling point at 11.3 kpa (K) [13] 36.5 [13] 45.6 [13] [4] Refrative index, nd at K [4] [4] [13] 535. [13] [14] P (kpa) [13] 39.3 [13] 38.1 [13] V 1 6 (m 3 mol -1 ) 77. [15] 389. [13] 48. [14] Aentri fator,.39 [13].319 [1].35 [1] Dipole moment, (Debyes) 1.37 [4].87 [4].39 [4] Constants of Antoine s equation, eq.4 A [16] [16] [16] B [16] [16] [16] C 7.8[ 16]. [16] 7.37 [16] TABLE III VAPOR LIQUID EQUILIBRIUM DATA OF THE BUTYLAMINE (1) + CUMENE () SYSTEM y1 ln 1 ln

3 International Journal of Chemial and Biologial Engineering 3:3 1 TABLE IV VAPOR LIQUID EQUILIBRIUM DATA OF THE TRIETHYLAMINE (1) + CUMENE () SYSTEM y1 ln 1 ln Mole fration of n -Butylamine in vapor phase Mole fration of n -Butylamine in liquid phase Fig. 1. VLE of the n-butylamine + Cumene system at 97.3 kpa. TABLE V CORRELATION PARAMETERS FOR ACTIVITY COEFFICIENT AND DEVIATION IN VAPOR-PHASE COMPOSITION FOR THE BUTYLAMINE (1) + CUMENE () SYSTEM Correlations A 1 A A 3 Deviation (Δy) Margules NRTL Blak TABLE VI CORRELATION PARAMETERS FOR ACTIVITY COEFFICIENT AND DEVIATION IN VAPOR-PHASE COMPOSITION FOR THE TRIETHYLAMINE (1) + CUMENE () SYSTEM Correlations A 1 A A 3 Deviation (Δy) Margules NRTL Blak Temperature(K) Composition Fig.. Temperature vs. Composition urves for the n-butylamine + Cumene system at 97.3 kpa. Fig. 1 shows the experimental vapor liquid equilibrium data for the n-butylamine + Cumene binary mixture. In Fig., the Temperature vs. Composition urves are drawn for the n- Butylamine + Cumene system at 97.3 kpa. Fig. 3 shows the plot of ln value of ativity oeffiients as obtained by UNIFAC method [17] vs. omposition for the n- Butylamine + Cumene system. The graph learly indiates positive deviation from ideal behavior for the binary system studied. The mixture does not form an azeotrope. Fig. 4 shows the plot of y vs. y for the n-butylamine + Cumene system using NRTL equation. 144

4 International Journal of Chemial and Biologial Engineering 3: M ole fration of n-butylamine in liquid phase Mole fration of triethylamine in vapor phase Mole fration of triethylamine in liquid phase Fig. 3. Plot of ln ln vs. omposition for the n-butylamine + Cumene system at 97.3 kpa., UNIFAC. Fig. 5. VLE of the Triethylamine + Cumene system at 97.3 kpa. 43. Mole fration of n-butylamine in vapor phase (NRTL) Mole fration of n-butylamine in vapor phase (exptl.) Temperature (K) Composition Fig. 4. Plot of y vs. y for the n-butylamine + Cumene system using NRTL equation Fig. 6. Temperature vs. Composition urves for the Triethylamine + Cumene system at 97.3 kpa. 145

5 International Journal of Chemial and Biologial Engineering 3:3 1 ln1, ln (Ativity oeffiients) IV. CONCLUSION Vapor-Liquid equilibrium data at P=97.3 kpa has been obtained for the two binary systems; n-butylamine + Cumene and Triethylamine + Cumene. Both mixtures are nonazeotropi in nature. Whereas the n-butylamine + Cumene binary mixture shows positive deviation from ideality, the Triethylamine + Cumene binary mixture shows negligible deviation from ideality. This work will be of great use in improving the databank for estimation of model parameters for mixtures formed by umene with amines, and thus will enhane the preditability of the group ontribution model. Mole fration of Triethylamine in vapor phase (NRTL) Mole fration of Triethylamine in liquid phase Fig. 7. Plot of ln ln vs. omposition for the Triethylamine + Cumene system at 97.3 kpa., UNIFAC.. Mole fration of Triethylamine in vapor phase (exptl.) Fig. 8. Plot of y vs. y for the Triethylamine + Cumene system using NRTL equation Fig. 5 shows the experimental vapor liquid equilibrium data for the Triethylamine + Cumene binary mixture. In Fig. 6, the Temperature vs. Composition urves are drawn for the Triethylamine + Cumene system at 97.3 kpa. Fig. 7 shows the plot of ln value of ativity oeffiients as obtained by UNIFAC method [17] vs. omposition for the Triethylamine + Cumene system. The graph shows nearly ideal behavior for the binary system studied. The mixture does not form an azeotrope. Fig. 8 shows the plot of y vs. y for the Triethylamine + Cumene system using NRTL equation. REFERENCES [1] B. K. Gill, V. K. Rattan, and S. Kapoor, Vapor liquid equilibrium data for N-Methylaetamide and N,N-Dimethylaetamide with Cumene at 97.3 kpa, Journal of Chemial and Engineering Data, 9, vol. 54, pp [] B. N. Raju, R. Ranganathan, and M. N. Rao, Vapor-liquid equilibrium still for partially misible systems, Indian Chemial Engineer, 1965, vol. 7, pp. T33 T37. [3] B. Kumar, and K. S. N. Raju, Vapor-liquid equilibrium data for the systems -methoxyethanol-ethylbenzene, -methoxyethanol-pxylene, and -ethoxyethanol-p-xylene, Journal of Chemial and Engineering Data, 1977, vol., pp [4] J. A. Riddik, W. B. Bunger, and T. K. Sakano, Organi Solvents: Physial Properties and Methods of Purifiation. 4th ed. Wiley- Intersiene: New York, [5] B. K. Sood, O. P. Bagga, and K. S. N. Raju, Vapor-liquid equilibrium data for systems ethylbenzene-anisole and p-xylene anisole, Journal of Chemial and Engineering Data, 197, vol. 17, pp [6] H. C. Van Ness, and M. M. Abbott, Classial Thermodynamis of Non-eletrolyte Solutions. MGraw-Hill: New York, 198. [7] C. L. Yen, and S. S. Woods, A Generalized equation for omputer alulation of liquid densities, AIChE Journal, 1966, vol. 1, pp [8] C. Tsonopoulos, An empirial orrelation of seond virial oeffiients, AIChE Journal, 1974, vol., pp [9] E. F. G. Herington, Tests for the onsisteny of experimental isobari vapor-liquid equilibrium data, Journal of Institute of Petroleum, 1951, vol. 37, pp [1] H. Renon, and J. M. Prausnitz, Loal ompositions in thermodynami exess funtions for liquid mixtures, AIChE Journal, 1968, vol. 14, pp [11] V. K. Rattan, S. Kapoor, and S. Singh, Isobari vapor-liquid equilibria of 1-butanol- p-xylene system, International Journal of Thermophysis, 6, vol. 7, pp [1] R. M. Stephenson, and S. Malanowski, Handbook of the thermodynamis of organi ompounds. Elsevier Publiations, [13] R. C. Reid, J. M. Prausnitz, and B. E. Poling, The Properties of Gases & Liquids. 4th ed. MGraw-Hill: New York, [14] J. A. Riddik, W. B. Bunger, and T. K. Sakano, Organi Solvents: Physial Properties and Methods of Purifiation. 3rd ed. Wiley- Intersiene: New York, 197. [15] D. R. Lide, CRC Handbook of Physis and Chemistry. 85th ed. CRC Press, 4-5. [16] T. Boublik, V. Fried, and E. Hala, The Vapor Pressures of Pure Substanes. Elsevier: New York, [17] J. Gmehling, J. Lohmann, and R. Wittig, Vapor-liquid equilibria by UNIFAC Group Contribution. 6. Revision and extension, Industrial Engineering Chemistry Researh, 3, vol. 4, pp