THE RICE INSTITUTE
ESTIMATION OF THE HEAT OF SOLUTION IN
IIYDR GER SULFlDE-MuNGETHANCLA:- INK-WAT Eli SYSTEM
by
Kasahiro Yorizane s/
A THESIS
SUBMITTED TC TEE FACULTY
IN PARTIAL FULFILLMENT uF TEE
REQUIREMENTS FuR THE DEGREE OF
MASTER UF SCIENCE IN CHEMICAL ENGINEERING
/ \
Houston* Texas May, 1955 \F ii
ACKNCWLBDGEMEfiT'
I wish tc gratefully acknowledge all those who so generously aided in the course of this investigation, especially to express my appreciation to:
Dr. Riki Kohayashi for continued advice and guidance.
Professor A. J. ITartsook for encouragement and the tenure of an assistantship.
Dr. Sakae Yagi, the professor of Tokyo University, for suggesting and recommending that I study in The Rice Institute.
My Family for their patience, encouragement, and financial assistance. iii
TABLE OF CONTENTS
Subject Page
Title Page i
Acknowledgement ii
Table of Contents iii
List cf Tables iv
List of Figures v
Nomenclature vii
Sucasary lx
Introduction 1
Derivation of Equations 4
Heat of Solution 4
Hypothesis of Chemical Reaction 6 Estimation of Solubility 9 Results and Discussions 11
Estimation of Hypothetical Chemical Equilibrium Constant ll Estimation of Solubilities 13 Calculation of Heat of Solution 2o
Discussions 55
Bibliography iv LIST OF TABLES
Table No, Subject Page 1 Conversion Table of Normality into Molality in Aqueous Monoethanolamlne Solution 12
2 Hypothetical Chemical Equilibrium Constant Ik 3 Solubility of Hydrogen Sulfide in Aque Us Kornethanclamine Solution 29 k Partial Kola! Heat ' f Solution of Hydrogen Sulfide in Aque us Mono- ethanolamine Solution 39 5 Partial Molal Heat of Solution f Hydrogen Sulfide in Aque ous Kono- etlanolamine Solution- 58
* V
LIST OF FIGURES
Figure No Subject Page
1 Hypothetical Chemical Equilibrium Constant as a Function f Partial Pressure at 25° C. 21
2 Hypothetical Chemical Equi’ibrium Constant as a Function of Partial Pressure at 45° C. 22
3 Hypothetical Chemical Equilibrium Constant as a Function of Partial Pressure at 60cC. 23
4 Slope of Figure 1, 2 and 3 as a Function of Normality 24-
5 Intercept of Figure 1, 2 and 3 as a Function of Normality 25
6 Slope of Figure 5 as a function of Temperature 26
7 Intercept of Figure 5 as a Function of Temperature 27
8 Partial M-lai Heat of So nation of Hydr gon Sulfide in 0,6 N Monoethanol- amine Solution as a Function of Partial Pressure 47
9 Partial Mclal Heat of Solution cf Hydrogen Sulfide in 1,0 N Mcno- ethanolamine Solution as a Function of Partial Pressure 48
10 Partial Mclal Heat cf Solution of Hydrogen Sulfide in 1.5 N Monc- ethanolamine Solution as a Function of Partial Pressure 49
11 Partial Molal Heat of Solution of Hydrogen Sulfide in 2,0 N Mono- ethanolamine Solution as a Function of Partial Pressure 50 vi LIST OF FIGURES (cont’d) Figure No. Subject Page
12 Partial Molal Heat of Solution of Hydrogen Sulfide in 3,0 H Mono- ethanolamine Solution as a Function cf Partial Pressure 51 13 Partial Molal Heat of Solution of Hydrogen Sulfide in 4.0 N Mcno- ethanolamine Solution as a Function of Partial Pressure 52 14 Partial Molal Heat of Solution of Hydrogen Sulfide In 5*0 N Mono- etbanolamine Solution as a Function cf Partial Pressure 53 15 Partial Molal Heat of Solution of Hydrogen Sulfide in Aqueous Monc- etbanolamine Solution as a Function of Temperature at 500 mm. isercury Partial Pressure 54 vii
NOMENCLATURE a activity
? partial molal free energy, cals/g mol.
E partial mclal enthalpy, cals/g mol*
Zk H heat of solution, cals/g mol.
I intercept of Figure
K Henry's constant k constant defined by equation (19)
Kx hypothetical c’ emical equilibrium constant m molality or number of moles
N normality
P total pressure, atmosphere p partial pressure, atmosphere
Q slope of Figure 5
R. universal gas constant
S slope of Figure i, 2 and 3
S partial mclal e^irupy, cals/g mol °fc
T temperature, rK. x liquid composition, mol fraction
Y defined by equation (3&) y va'^r composition, mcl fraction
% activity c efficient Superscript
V vapor phase
L liquid phase
Subscript
1 water
2 monoethanclai;.ine
3 hydrogen sulfide if reacted product
c oh stoical absorption p physical absorption
T hypot! etical reaction ix
JOMKARy
An hypothetical chemical reaction between hydrogen sulfide and monoetl anoiamlne is set up to permit thermo¬ dynamic calculations of the partial heats of solution of hydrogen sulfide in aqueous monoethanclamine solutions.
The solubility data of hydrogen sulfide in various concentrations of monoethanclamine and water were used to make the calculations. The partial heats of solution of hydrogen sulfide were calculated for 0.6, 1.0, 1.?, 2.0,
3.0, 4.0, and £.0 normal mcnoethanolamine solution at 1?,
25, 35? 45, 55, and 60 deg. C. at partial pressures of hydrogen sulfide ranging from 25 mm of mercury to 700 mm cf mercury. The partial heat of solution calculated for the 100 deg. C. isotherms are to be considered a*> extra¬ polated values since no experimental solubility data is available at 100 deg. G.
The accuracy with, which the derived equation represent the solubility data is determined by tabular conrariscn of the calculated values with the original experimental data. Over the range cl conditions studied, the partial heat of solution cf hydrogen sulfide is found to vary from -4,000 to -13,000 calorics per greua mol of dissolved hydrogen sulfide. Tho pronounced effect cf partial pres¬ sure, ethanolamine concentration, and temperature on tho partial heats of solution of hydrogen sulfido are presented graphically . 1 INTRODUCTION
The purpose of this study is to determine the effect of temperature, ncnoethanolamine concentration, and partial
pressure of hydrogen sulfide on the heat vf solution f hydrogen sulfide in aqueous m noethanolamine solution.
The ethanolamine have found wide usage as an absorbent
for the removal of acid gases from streams primarily composed
of-gases which are nonreactlve to the basic amine radical.
Specific examples of their appl’cation are the removal of hydr gen sulfide from natural gas and the removal of carb'n dioxide and hydrogen sulfide from refinery gases. While
the absorption of acid gas taking place at low temperatures may be effected c mpletely, the amines became practically
non-alkaline at elevated temperatures and is no longer In equilibrium with acid gas f substantially zero partial
pressure. Thus, by elevation f t.e peruture and the reduction f the partial pressure of ti e acid gas ver the
solution the spent amine solution may be regenerated and reused.
The solubility of carbon dioxide (1),(6), (10), (11) and hydrogen su fide (1C), (15) in aqueous etan lamine solution Lave been reported by several authors. Altl ough the reaction mechanism between hydrogen sulfide --r carb n dioxide and the etherolamine are not understood in detail, it has been>postulated that they react t form amine sulfide 2 or amine carb'nate, respectively (10).
In commercial absorbers for the purification of acid
gases one limitation on the capacity of the units is imposed by the heat effects resulting from the absorption.
The heat effects acc npanyin;; the absorption f acid gases might be expected to be sensitive to the activity of the acid gas in equilibrium with the solution, t-e concentration
f the aqueius amine solution, and the temperature since the solubility f the acid gases are greatly affected by
these variables. The solubility data of hydr gen sl.fde in monoethanelaxaine fr-m the work f Riegger, Tartar and Lingafelder (15) are treated thermodynamically to determine
the partial heat f solution f hydrogen sulfide in vari us aqueous mono ethanoiamine solut;ens. The heat of solution f substances may be determined
(1) by Calorimetric means involving precise experimental
technique, or
(2) by thermodynamic calculations.
The second procedure has been cl sen in this investigation. The evaluation of the partial Lout of solution requires the differentiation it a relationship expressing the partial fugacity of that c mponbnt with respect t-' temperature.
This presupposes the existence of a function representing the partial free energy r partial fugacity of the component in question as a function of pressure, temperature, and 3 composition* The differentiation of tho relationship f r
fugacity wit* respect to temperature may be made analytical¬ ly (13) or by numerical methods (3). The former procedure may be conducted more consistently provided, a function expressing the fuoaclty f the component in question as a
function pressure, temperature, and cmp- sitions can be found. Such a function can hardly be obtained unless ti e
chemical react! n is taken into account. Scant experimental. data- on '.the partial heats of solution of hydrogen sulfide In•aqueous athanolamine solution is reported by Bottoms (2). Lyudkovskaya and Leibush (11) calculated the'partial heat of so .tail on of carbon dioxide in aqueous mono ethane lamina and triethanolamine solutions.
They reported.th% partial heat of solution of. carbon dioxide to- be dependent on amine concentration and the concentration cf carbon dioxide in solution, being independent of temp¬ erature from 0 deg. C. to 75 dag. C, T The author attempts t- find the effect of temperature on the heat of solution by Introducing an analytical express¬ ion for the solubility involving the partia’ pressure of hydrogen sulfide, the temperature, and an hypothetical chemical equi Librium constant. DERIVATION OF m ATIONS Reat of Solution The equations for computing the heat of solution are obtained from fundamental thernedynamic relations of free energy. Those relations are presented below in the derivations which follows. The free energy of hydrogen sulfide in the vapor state (containing inert gas) may be expressed as a function of pressure, temperature and compositions.
^3 = (1) where yQ is the composition of inert gas in gas phase, then 45; ^ p,y3,y2*y0
dy (2) 0 0 (y3,y0 ' *>,1*73,72 The free energy of hydrogen sulfide in the solution may be expressed as a function of pressure, temperature and compositions, as
= f(P,T,x3,X2) (3) then
dP dT 3 - OP A,*3,X2 partial molal free energy of hydrogen sulfide in the vapor state must equal the change in the partial molal free energy of hydrogen sulfide in the solution, d?^ = • (6) Hewriting equations (2) and (**) at constant pressure and substituting equation (6)j pK. dA, pyj, dT+lr-*) p dyfbrl3 T #2dx x, 3T P,y ^3 ,T * P,X ,X * 3 3 3>3 2 3 <4§)ax ^2 . (7) 2 P,T,X3 Since y, - B. = - and 9^ HI l , 0 l^y3/p>T y3 #•^syr2,po»-T “y/y^C y° P»T if the vapor phase behaves as an ideal gas. If the composition of the solution in the liquid phase is kept consatant, the equation (7) reduces tc RT g —dy-, = ~ 3, t MdT y3 3 T From equation (5) ?3 = ?3 6 then r?±Zl)1 _ ”§ - 2 dT ^P,x3,x2" RT ^ _ . jg-IL. (8) RT2 _L -.V where II — II3 — 1T3 Hypothesis cf Chemical Reaction Hydrogen sulfide is absorbed by aqueous noncethanelamine solution. Let this solution be call the overall solution. If we analyse this reaction in the following two steps: (1) chemical reaction is performed between pure monoeth.anol- amine and hydrogen sulfide at the partial uressure (hypo¬ thetical chemical reaction), (2) this product solution is diluted by the water which is saturated with hydrogen sulfide at the same partial pressure. If the activity cf the hydrogen sulfide in the overall solution is assumed equal to the activity of hydrogen sul¬ fide in the hypothetical chemical reaction utilizing the same standard state for hydrogen sulfide in the two solutions. In order to find the activity cf hydrogen sulfide in the chemically absorbed solution, Dolezalel^s assumption (h) (7) is used. Anhydrous reaction: l '• 7 H 2S + MEA = MEA-H2S (9) Original moles: m^c Moles present at equilibrium: The total number of moles being (m2 + m^c - m^), the true mole fraction in the anhydrous solution are related by the equation: m2 - 1% X (10) 2T n? + m3o - D!. a3c "* ^ (11) m2 + n3c * (12) m2 + m3c “ \ If the chemical equilibrium constant Is defined in the terms of mole fraction, then ~ X2T *3T (13) then mi|.(ra2 m^c - *%) 1 (1*0 x (m2 -.:-\)(ra^c - ) • Let *2 (15) s2 -t- X43c a3c x3’ (16) + m3c 8 and (17) be tl e apparent mole Traction. Then Kpt _ yu - y> Xx-ri x2' x3' This is solved for designating * 1 5 as constant. We obtain = i ± £(l - .kxg’x:^*)^* (20) In the true species the activity is related to mole fraction (2*> On the other hand in the overall solution zn a3 ~ 3X3 ~ mg + nj -t- 55.506 (21‘) Since a3« = a3, 9 if we assume 22 Y3 -r3’ ( ) then k is related in the following equation l*2iLi*d k = (23) (1 - X,)^2C: Estimation of Solubility Equation (19) may be expressed by: = 4^k • <*> Correlating the experimental data, may be obtained as a function of the partial pressure and the normality of the solution at constant temperature, and the temperature dependence subsequently found graphically. Solubilities of gases are calculated by equations (16j and (23), denoting m 55 m 3 3c *■ ®3P • (25) We obtain 59.506 m|c +■ [55.506(m3pi* m2 + 55.506) - m2n3p 2 - kA (mg +■ 55.506) Jm3c - m2ra3p(a3p + + 55.506) = 0 (26) This m3c is solved by the form of - b t >/b ^ - 4a c m3c 2a (27) where a =■ 55.506 b =55.506(n3p+ n2 + 55.506) - - kA (mp + 55.506)2 10 C — — m2m3P^m3P + m2+ These calculated values are checked by the data of RIegger, Tartar and Llngafelder (15) and those of Leibush and Stanerson (10). 11 RESULTS AND DISCUSSIONS Estimation of the Hypothetical Chemical Equilibrium Constant Kx Solubility data of hydrogen sulfide obtained from Riegger, Tartar and Lingafelder (15) are g'ven in moles of hydrogen sulfide per mole of monoethanolamine at the partial pressures of 700, 600, 500, 4-00, 300, 200, 100, 50 and 25 nm mercury for 0.6, 1.0, 1.5, 2.0, 3.0, 4-.0 and 5*0 N monoethanelamina solutions at the different tempera¬ tures of 25, 4-5 and 60 dec. C. In order to calculate the mole fraction of hydrogen sulfide in the solution, the normality of mcncethanolamine solution is changed to the molality. The conversion table used is tabulated in Table 1. The density data of different concentration of monoethanelamine in water are obtained from Mason and Dodge (12). Solubilities of gases in water are estimated by the Henry’s constants which appear in the International Critical Tables <8) <140. m^p is calculated by the following equation 55.506 P3/X3 m = (2S) 3p X - P3/K3 m^Q in equation (15) (16) and (17) is estimated, by equation (25) k is calculated by equation (23) and the value of is estimated by equation (24-). fabie 1 Conversion Sable of Normality into Molality in Monoethanelawin© Solution Normality Molality 0.6 o.6,,’4l c.93 0.9679 1.0 1.0670 1.5 1.6536 2.0 2.2809 2.5 2.9526 3.5 53 b.O?*° 5.2870 5.0 7.1777 13 These values are tabulated in Table 2. Estimation of Solubilities Hypothetical chemical equilibrium constant K versus A partial pressure for different normality at constant temperature are plotted on log-log paper as in Figure 1, 2 and 3* The best straight line through the data have been drawn visually. The slopes of these lines are shown on Figure ^ as a function of normality while being indepen dent of temperature and it shows* Slope * S » 0.625 N~ °*3°9 (29) Intercepts of these lines in Figure 1, 2 and 3 are plotted on Figure 5 as a function of normality on the parameter cf temperature. In order to find the temperature depend¬ ence of these intercepts, slopes of Figure 5 versus the temperature T in degree Kelvine absolute is plotted as straight line on Figure 6 and gives* Slope r Q(T) = 0.00775 T - 4.47 (30) Intercepts of Figure 5 versus temperature T is plotted on semi-log paper as straight line as in Figure 7 ami gives: 0lh5 T Intercept r I(T) =■ 5.352 XIO^XIO* °* (31) If we consider the particular range of this absorption, the hypothetical chemical equilibrium constant will be estimated by the following equation* 14 Table 2 Hypothetical Chemical Equilibrium Constant Tamp. Partial Mols E?S . *x mm Hg ^°1 ^ 0.6 N MEA Solution 700 1.148 .01260. 3.9992U 5,069 600 1.126 .01236 3.999203 5,018 500 1.101 .01209 3.999046 4,192 400 1.080 .01186 3.999104 4,463 25 300 1*053 .01157 3.99§913 3,67? 200 1.027 .01129 3*998729 3,146 100 .986 .01081 3.997910 1,913 50 .934 .01028 3.996070 1.. 017 25 .866 .00954 3.993327 '598 700 1.124 .01234 4.000519 600 1.097 ,01205 3.999910 ),!,I f j ),M,r T T 500 1 • 070 3.9991, 400 1.045 .01148 3.998863 3,517 45 300 1.011 . .01112 3.997979 1,978 200 .971 .01068 3.996858 1,272 100 .908 .00999 3.994732 758.3 50 .826 .00910 3.991.447 466.7 55 .731 .00806 3.987449 317.7 700 1.083 .01190 3.999575 9,411 600 1.056 .01160 3.99o£38 3,441 500 1.027 .0 129 3.998021 2,020 400 .995 .01094 3.997120 1 3B£ 60 300 .96c .01056 3.996082 1,020 200 .908 •00999 3.994251 694.8 100 . 8ii .00894 3.990550 422.3 50 .694 .00766 3.985661 278 .0 25 .551 .00609 3.9795-4 194.3 15 Table; 2 (cont'd) Hypothetical Chemical Equilibrium Constant Temp. Partial Mols E0S k °C. Pressure *3 mm Kg Mol MEA 1.0 . U MEA Solution 700 1.086 .02007 3.998149 2,160 600 1.072 .01982 3.998073 2,074 500 1.058 ,01956 3-997998 1,997 400 1.042 ,01927 3.997770 25 300 1,022 .01891 3.997278 V 200 .998 .01847 3.996456 1.128 100 .956 .01771 3.993886 653.2 ?2- .902 .01673 3.990780 432.8 25 • O 33 .01547 3.9^5560 276.0 700 I.051 ,01928 3.997089 1,373 600 1.033 * 0191J. 3.997064 1,361 5oo 1.012 .01873 3.996127 1,032 4oo ,01638 3.995388 666.3 45 .300 .967 .01791 3.994:74 674.- 200 .92’ .01722 3.9919:7 498. 100 .86 .OI603 3.987760 325. 50 .782 .01453 3.962029 221. 25 .686 .01 77 3.975 13 159. •N^C 3\coro v 70c 1.64o 1 3.997931 1,932 600 .011 .01871 3.996 31 1,060 500 .984 .01822 3.994704 '754-3 400 .952 .01764 3.99;816 60 300 .916 .01689 3.990654 r27.0 200 .863 .01601 3.987236 312.4 100 .757 .01408 3.979909 I98.9 50 .634 .01182 3.971075 137.3 25 .490 .00916 3.960547 .i00,4 16 Table 2 (cent16) Hypothetical Chemical Equilibrium Constant . Temp. Partial Hols H2S °C. Pressure k mm Hg Mol HE& 1.5 N MEA Solution 700 l.O^O .02940 3.99548; 884.5 600 1.041 .02924 3.99539 866.3 500 1.032 .02899 866.3 400 1.020 ,02867 793.5 25 300 1.002 .02818 .993918 656.7 200 .02755 520.2 100 .02631 339.2 50 .02472 5.982215 223.9 25 .02262 149.1 700 1.011 ,02842 3.993247 600 .996 .02801 3.992192 500 .980 .02757 3.991028 400 .961 .02705 3.989540 381.4 45 300 .939 .02645 3.967716 324.6 200 .900 .02538 3.9839£6 248.8 100 .826 .02334 3.976332 168.0 50 .742 .02102 3.967237 121.1 25 .631 .01793 3.954842 87.6 700 .998 .02807 3.992743 550.2 600 .970 .02730 3.990051 401.1 500 .945 ,02661 3.987726 324.9 400 .912 .02571 3.964492 256.9 60 300 .876 ,02472 3.980957 209.1 200 .822 .02323 3.975411 161.7 100 .708 .02007 3.963132 107.5 50 .576 .01639 3.948579 76.8 25 .433 .01237 3.932396 5£.2 17 Table 2 (cont’d) Hypothetical Chemical Equilibrium Constant Temp Partial Mels H2S °C. Pressure k mm Hg Mol MEA 2.0 N MM Solution 700 1.033 3.991908 493.3 600 1,025 3.991730 482.7 ^00 1.016 3.991287 458.1 4oo 1.006 .03819 3.990751 431.5 25 300 .990 .03761 3.990189 406*7 200 .966 .03673 3.986581 297.1 100 .919 .03500 3.980472 203*8 .^56 .03i68 3.971399 !3g.9 2 5 .777 .02976 3.959629 98.1 700 .988 .03753 3.987246 312.6 600 .975 .03706 3.985914 283.0 500 •960 .03651 3.984281 253.3 400 .943 .03588 3.982354 225.7 45 300 .921 .03508 3.979666 195.7 200 .880 .03357 3.974113 153.5 100 *795 .03042 3.961880 103.9 50 *7 06 .02711 3.948736 77.0 25 .601 .02317 3.933023 58.7 700 .968 ,03680 3.985146 268*3 600 ,944 .03592 3.981984 221.0 500 .916 .03489 3.978212 182.6 4oo .885 .03375 3.974008 152.9 60 300 .847 *03235 3.968755 127.0 200 .793 .03035 3.961093 101.8 100 ,674 .02591 3.943600 69.9 50 .532 .02057 3.922307 50.5 25 .388 .01508 3.900656 39.3 18 Table 2 (cont'd) Hypothetical Chemical Equilibrium Constant Teivp.1 Partial Mels H2S Of Pressure x k mm Hg Mol MEA 3 he 3.0 N MEA Solution 700 1.011 .05779 3.960911 20G.5 600 1.004 .05741 3.980267 201.7 500 .996 .05698 3.979404 193.2 400 .985 .05639 3.977846 179.6 2 5 300 .970 .05558 3.975436 161.8 200 ,946 .05427 3.970920 136.6 100 *893 .05139 3.959797 96.5 50 .£19 .04733 3.943426 69.7 25 .730 .04241 3.923183 51.1 7 00 .05492 3.970891 136.4 600 .05438 3.969127 128.6 500 .934 .05362 3.966733 119.2 4oo .918 .05275 3.963736 109.3 45 300 .05128 3.958236 94.8 200 .846 .04882 3.948636 76.9 100 .748 .04341 3.926961 53.8 50 .648 .03762 3.904548 40.9 25 .533 .03132 3.878520 31.9 700 .948 .05353 3.970330 133.8 600 .910 .05232 3.961359 102.5 500 ♦ 880 .05068 3.955000 87.9 4oo .848 3.948206 76.2 60 300 .810 3.940065 6 5.7 200 3.927165 53.9 100 3.898764 36.5 50 .474 .02795 3.864835 28.6 25 .331 .01969 3.832338 22.9 19 Table 2 (cont*) Hypothetical Chemical Equilibrium Constant Temp. Partial Mo Is H0S Oft* Pressure x k mm Eg Mol MSA 3 4.0 N MEA Solution 700 998 .07986 3.962:63 105.0 600 991 .07934 3.960958 10it'5 500 980 .07853 3.959177 97.0 400 971 .07786 3.956551 91.1 25 300 955 .07668 3.952444 83.I 200 931 .07501 3.945663 72.6 100 870 .07034 3.927367 54, T 50 784 .06383 3.900540 39.2 700 .940 .07557 3.945877 72.9 600 .928 .07467 3.942709 65.0 500 • ?13 .07356 3.938591 64.1 400 • 897 .07236 3.934198 59.8 45 300 .869 .07026 3.925919 200 .810 ,06649 3.910706 100 .714 .05846 3.878039 31.8 50 .601 .04967 3.842505 24.4 25 .487 .04063 3.806521 19.7 700 .07326 3.936920 62.4 600 3.929853 56.0 500 3.921697 50.1 400 3.910432 43.7 60 300 3.897300 37.9 200 .05’ 3.877516 31.7 100 .04747; 3.838301 23.7 50 .03564 3.786568 17.7 25 .291 .02468 3.744171 14.6 20 Table 2 (cont'd; Hypothetical Chemical Equilibrium Consatant Temp.V Partial Mo Is IlpS S, Pressure ~ mm Kg Kol KEA 5.C K MSA. Srluti^n 70v .Jyj .10191 3.937079 uOu .984 .10126 3.935205 500 .974 .10034- 3.932027 400 .963 .09932 3.928565 25 300 •94-5 .09764- 3.922255 200 .918 .0Q512 3*912253 100 .652 .C815O9 3,»8i200 50 .758 .07986 3.848819 25 .64-3 .06858 3.802722 700 .927 .09596 3.909229 6oo .914- .094-74- 3.9C8516 5oc .899 .09333 3.903081 400 .880 .09154- 3.895929 45 3u0 .850 .08870 3.864506 200 .800 .08392 3.8648(6 100 .684 .07263 3.818530 5o .564 ,06066 3.770815 25 .453 .04931 3.725:48 700 .891 .09258 3.899417 600 .865 .09 XL 2 3.889359 500 .837 .08746 3.878490 400 .801 ,08401 3.8643(7 60 300 .753 .07938 3.845417 200 .683 3.817596 100 .54-7 !0589** 5 s .386 .04.-33 3.697922 ! , Ofovno -p*c' r- vn FIGURE 1 K.ASAFUNCTION OF PRESSURE 5 6 7 B D 1 ?v B 7 B O 1 ,:2 ’/rtf ; -v'i ' • A- ? o 7 H '.* » t 2b Q: o o > o H -J o < 2 an o CO < CO LU cr o LX. V"'-- • VfeV/ . 28 arl(T) NQ(T) p| 0 0ll, (5.352 x 10^x10“ » ‘5 N°.0077? T - ^-.4-7 0,309 0.625 N' (32) *p3 Then, b® estimated by equation (27) combining m 3P of equation (28). Solubilities of hydr gen sulfide are calculated and these calculated values are tabulated in Table 3» Calculation of Heat of Solution According to equation (8) the heat of solution may be estimated by the following relation: S 3lg y = - BT f 3) (33) If the total pressure of gas phase is 1 atmospheric pressure, then p y3s= 3 Differentiation of equation (32) with respect to T reduces to /^ln p^\ ^1 9 In Ky 1 3ln^ _ In H ^ Q L 'P,X3,X2 S ?>T ^ S ? T S (35) Differentiation of equation (23) with respect to T at constant X3, X2, and P ,3k. 4x3 3x, I = WP>X3,*2 29 Table 3 Solubility of Hydrogen Sulfide in Konoetbanolarrdne Solution Term. Partial Slubility Error Absolute °C*. Pressure Molality % Average rm Eg Calo. Obs. Deviation 0 ,6 H MEA Solution 700 .7192 .7164 .4 600 *7051 .7026 .4 500 .6904 .6870 .4 400 .6752 .6739 0 u-*. 25 300 ,6582 .6571 .2 .4 200 .6396 .6408 - .1 100 .6132 .6153 - .3 50 ,5846 .5828 • 3 25 .5470 . 54 4 1.3 700 ,6800 .7014 -2.9 600 .6684 .6845 -2.4 500 .6570 .6677 -1.6 400 .6438 .6521 -U3 45 300 ,6290 .6309 - .3 1.5 200 .6090 .6059 .5 100 , 5726 .5666 1.1 50 .52) .5154 25 # jy .4561 -2*5 700 .6546 .6758 -3.2 600 .6440 .6589 -2.3 500 .6317 .64o8 -1.4 400 .6181 .62)9 - .5 60 300 .6006 .5990 .3 2.7 200 .5746 .5666 1.4 100 .5196 . 50-61 2.6 50 .4366 .8 25 .3034 -11.8 30 Table 3 (cont*d) Solubility of Hydrogen Sulfide in MiSA Solution Temp. Partial Solubility 3rror Absolute cC. Pressure Molality % Average m Hg Calc. Gbs Deviation 1*0 N KKA Solution 700 1.1611 1.1588 ♦ 2 600 1.1457 1.1438 .2 500 1.1284 1.1289 - .0 400 1.1101 1.1118 - .2 25 300 1.0884 1.0905 - .2 .4 200 1.0636 1.0649 - .1 100 1.0214 1.0201 .1 50 *9712 .9624 .9 25 .9001 .8888 1.3 700 1.1076 1.1121 - .4 600 1.0937 1.1022 - .8 500 1.0780 1.0798 - .2 4oo 1.0606 1.0595 - .0 45 300 I.O38O 1.0318 .6 1.0 200 1.0061 .9912 1*5 100 .9404 .9219 2.0 50 .8523 .8344 2.1 25 *7196 .7320 700 1.0651 1.1097 -4.4 600 1.0502 1.0787 -2.8 500 1.0324 I.O499 -1.7 4oo 1.0105 1.0158 - .5 60 300 .9817 .9794 2.4 200 *9367 .9208 1.7 100 .8366 .8077 3.g 50 .6958 .6765 2.8 25 .4806 .5228 -8.1 31 Table 3 (cont’d) Solubility of Hydrogen Sulfide in MBA Solution Temp Partial Solubility Error Absolute °C. Pressure Molality % Average mm Hg Calc. Obs. Deviation 1, ,5 N MBA Solution 700 1*7447 1.7365 .5 600 1.7260 1.7216 •3 500 1.7051 1.7067 *■» .0 400 1.6822 1.6869 * .3 2 5 300 1*6539 1.6571 - .2 .5 200 1.6165 1.6191 - .2 100 1.5487 1.5446 .3 50 1.4633 1.4487 1.0 25 1.3447 1.3263 1.4 700 1.6653 1.6722 .4 600 1.6464 1.6472 - .0 500 1.6251 1.6207 * 5 400 1.5985 1.5893 .6 45 300 1*5642 1.5529 .7 1.0 200 1.5121 1 §TO8T 1.6 100 1.4047 1.3660 2.8 50 1.2567 1.2271 2.3 25 1.0457 1.0435 .2 700 1.5929 1.6505 -3.5 600 1.5706 1.6042 -2.1 500 1.5441 1.5628 -1.2 400 1.5101 1.5083 .1 6o 300 1.4640 1.4487 1.1 3*5 200 1.3903 1.3594 2.3 100 1.2293 1.1709 5.0 50 I.0030 .9526 5.3 25 .6782 .7161 -5.3 32 Table 3 (cont*d) Solubility of Hydrogen Sulfide in KEA Solution Temp. Partial Solubility Error Absolute °C. Pressure Molality * Average mm Ilg Calc. Gbs. ■Deviation 2.0 N MBA Solution 700 2.3669 2.3562 .5 600 2.3^36 2.3379 .2 500 2.3180 2.3-174 .0 TOO 2.2848 2.29H6 .4 25 300 2.2509 2.2581 - .3 .4 200 2.1987 2.2033 - .2 100 2.0980 2.0961 - .0 50 1.9686 1.9525 .8 25 1.7932 1.7723 1.1 700 2.2531 2.2535 - .0 600 2.2282 2.2239 .2 500 2.1980 2.1897 .4 400 2.1617 2.1509 .5 300 2.1122 ■ 2.1007 .5 1.2 200 2.0340 2.0072 1.3 100 1.8757 1,8133 4.0 50 1.6593 1.6103 3.2 25 1.3601 1.3708 - .8 700 2.1405 2.2079 -3.0 600 2.1024 2.1532 -2.4 500 2.0716 2.0893 - .8 HOC 2.0228 2.0186 .2 300 1.9547 1.9319 1.2 2.8 200 1.8462 1.8088 2.1 100 1.6108 1.5373 4.8 50 1.2895 I.2134 6.3 25 .8421 .8850 —4# 8 33 Table 3 (coat'd) Solubility of Hydrogen Sulfide in HEA. Solution Temp. Partial Solubility Error Absolute °C. Pressure Molality % Average mm Hg Calc. Qbs. Deviation 0.93 N MEA Solution (Ref. 10) 1.8? *3§7? .4486 -18.1 -? 8.6 .7670 .70?4 6.8 13.? 2? 3.14 .3878 .4486 -18.0 15.2 17.2 .7917 .7054 12.3 ?0 13*4 .3671 .4486 -18.O 14.2 6?.6 .7786 .7054 10.4 2 .? H MEA Solution (Kef. 10) 4.2? 1.6002 1.3287 21.2 11.0 2.1384 1.8129 17.6 1? 16.4 2-3046 2.0314 13.4 14.4 ?7.? 2.8653 2.4979 6;7 4.0 l.1028 1.1013 .1 7.1? i*573i 1*328? 18.? 20.4 2.2129 1’.8129 22.0 31.4 2.3388 2.03X4 i?.l 11.8 104 2.6821 2.4979 7*4 124 2.7208 2.?21? 7*8 30.6 1.6179 1.8129 10.7 ?0 121 2.33O6 2.O3I3 14*9 10.7 348 2.6607 2.4979 6? 34 Table 3 (cont‘d) Solubility of Hydrogen Sulfide in KEA Solution Temp Partial Solubility Error Absolute °C. Pressure Molality % Average M3 Hg Calc. obs. Deviation 3.0 N MBA Solution 700 3.6509 3.6247 .7 600 3.6161 3.5996 .4 500 3.5769 3.5709 .2 400 3.5286 3.5315 - .1 25 300 3.4652 3.4777 - .4 .4 200 3.3722 3.3917 - .6 100 3.1864 3.2017 5o 2.9478 2.9364 .4 : 25 2.6323 2.6173 .6 700 3.4423 3.4347 .2 600 3.4013 3.3988 .1 500 3.3508 3.3486 .1 400 3.2864 3.2913 - .1 45 300 3.1980 3.1945 .1 1.6 200 3.1004 3.3032 -6.1 100 2.7724 2.6818 3*4 50 2.3926 2.3233 3.c 25 1.8889 1.9110 -1.2 700 3.23U 3.3989 -4.9 600 3.1752 3.2626 -2.7 500 3.1090 3.1551 —1.4 400 3.0227 3.0403 - .6 60 300 2.9022 2.9041 - .0 3.1 200 2.7106 2.6926 .7 100 2.3042 2.2372 2.9 50 1.7672 1.6994 3.9 25 1.0549 1.1867 -11.0 35 Table 3 (ccnt'd) Solubility of Hydrogen Sulfide in MEA Solution Temp. Partial Solubility Error Absolute °C. Pressure Molality % Average mm Hg Calc. Obs. Deviation 4.0 N MEA Solution 700 5.3669 5.2764 1.7 600 5.3169 5.2394 1.5 5oo 5.0583 5.1813 1.4 40C 5.1857 5.1337 1.0 300 5.0859 5.0491 .7 1.7 200 4.9377 4.9222 .3 100 4.6366 4.5997 »o 5o 4.2550 4.1^50 2.7 25 3.7619 3.6322 4.9 n 700 5.0835 4.9698 l - • 3 600 5.0190 4.9063 2* 3 500 4.9451 4.8270 2. 4 400 4.8498 4.7424 4. 4 300 4.7178 4.5944 *■- • 7 5.3 200 4.5117 4.33,01 4. 2 100 4.0870 3.7749 8. 3 50 3.5399 3.1775 11. 4 25 2.8323 2.5748 10. 0 700 4.6849 4.8059 -2.6 600 4.6017 4.6737 -1.5 500 4.4990 4.5362 - .8 4co 4.3651 4,3406 .6 306 4.1783 4.1133 1.6 3.5 200 3.8829 3.7749 2.9 100 3.2684 3.0717 6.4 50: ■ 2.4762 2.2470 10.3 25 1.4644 1.5385 -4.8 36 Table 3 (oont'd) Solubility of Hydrogen Sulfide in 1-SA Solution Temp. Partial Solubility Error Absolute °C. Pressure Molality % Average K031 Eg Gale. Obs. Deviation 5.0 K ME& Solution 700 7.2838 7.1134 2.4 600 7.2372 7.0632 2.5 500 7.1247 6.9914 1.9 MOO 7.0458 6.9124 1.9 PS 300 6.9004 6.7832 1.? 2.9 200 6.6794 6.5894 1.4 100 6.2334 6.1157 1.9 $0 5.6734 5.4409 4.3 25 4.9650 4,6151 7.8 700 6.8079 6.6540 2.3 600 6.7146 6.5607 2.3 500 6.6007 6.4530 «3 4oo 6.4541 6.3I06 2,2 45 300 6.2508 6.1013 ,4 4.2 200 5.9313 5.7424 3.0 100 5..2855 4.9098 7.6 50 4.4697 4.0484 10*4 25 , 3.4385 3.2516 5.7 700 6.2672 6.3956 -2.0 600 6.1466 6.2090 -1.2 5C0 5.9>61 6.0080 - .2 400 5.8014 5.7496 .9 60 300 5.5277 5.4050 2.3 5.0 200 5.1048 4.9026 4.1 100 4.2334 3*9264 7.8 *0 3.1412 2.7707 13.4 25 1.7709 2.0457 -13.4 37 considering equation (16) /3 k\ 4x3 m2 >3c 1 x 2x l2 2 (*d f'P,x3,x2 C - 3^ 3 + E^C) 2T 4-x- 3 n 3D (36) x x 12 m 2 (l -* 3)^ 3 ( 2 m^) dT since m3c + n^r r: constant. Differentiating equation (28) 55.506 - g?.-g06 ,„i£a JLS P a ) (37) 2i 'p,x3,x2 (K3-P3) 33T 3S? .3In KJJ.. may be estimated using equation (36) and T 2 'P,X3,X2 (37) together with the differentiated form of equation (24-) 4 /li?2k) - L ii - „ 2k *• ^ - U2 3T 42 1 m2 55.506 2?3 2*3 P(K3ST - P3^T 1 (4 - W- Kj (1 - x3)12 m3c (KEtl)2l = f 3»2».5« Ir >p, . Uh) 2 3 LKX (X - X3> m|o If we designate the first parenthesis by Y, then / ^ In !LA 2 2 2*: [ —-—-XI — - YK ~r— 4* Yp,-r— 0 (30 ' 2 T A x x ^ ^ T 3^)T Substituting this equation into equation (35) we obtain, /2ln p3\ _ Yp3 2*3 ¥%P3 2 In p3 \ 2 T ' P,x3,xo" S 2T “ S 2 T 36 1 ^lnI_lnN^Q STi S~TT or iKj «>ln I 2q 2|lnpvv Sp In II 3 St ' ? i ~ 7T ^ 1 'P>*3, *2 s * i K3P3 Since y^ by equation (34), equation (33) may be written as: 2*3 2 In I n Yp In N-*r-*^Ql 3 ^T 'd T 2T ZlH = - RT‘ S -f*YK p^ (39) 3 P,x3,x2 Henry’s constants, are expressed as an analytic function of temperature by applying Horner’s method (16): 2 K3 = 4.229X10 + 12,16(1 - 286,16) t 0.043(T - 288,16) *(T - 298.16) - 0.0004(T - 288.16)(T - 298.16) x(T - 318,16) (15 - 60°C.) (40) 2 K3 - 11.912 X10 + 15.88(T - 343.16) - 0.373(5* - 343.16)(T - 353.16) + 0.0C5(T - 343.16MT -353.I6)(T - 363.16) (70 - 100°c.) (4i) The derivation of the resulting function appears in the solution of equation (39). Calculated data are tabulated in Table 4 and plotted Figure 8 - l4. 39 Table 4 Partial Kolal Heat .of Solution of Hydrogen Sulfide in Aqueous Monoetl anolanine Solution Partial EoS in 9ln p Heat of IIPS in 9ln p Heat of Pressure ^Soln. ^ T Soln. Soln. 3 T Soln. mm Eg Molality cals/gnol Molality cals/gmol 0.6 N MEA Solution Temperature Temperature i5°c. 25° 0. 700 • 7493 .02792 -4,60? .7192 .02434 -4,300 600 .7307 .02807 -4,632 .7051 .02467 -*K359 5*00 .7125 .02831 -4,672 .6904 .02518 -4,44o 400 .693b .02872 -S738 .6752 .02601 -4I596 300 *6731 .02936 -4,865 .6582 .02751 -4,860 200 .6531 .03119 -5,146 .6396 .03050 -5 388 100 .6271 .03591 -5,926 .6132 .03699 -6,535 50 .6034 .04092 -6,753 .5846 .04199 -7,417 *5 •mi .04385 -7,235 .5470 .04433 -7 831 10 .5129 .04519 -7,457 • 8-609 .04530 -8,003 5 .4237 .04547 -7,503 .3^69 *b4550 -8,038 35°G. 45oc. 700 •6 Table 4 (cont’d) Partial Kolal Heat of Elution of Hydrogen Sulfide in Aqueous Monoethanolanin e Solution Partial H .S in 9 In p Heat cf H^S in 3ln p Heat of Pressure Soln. a T Soln. 2Soln. "fT Soln. mm Hg Molality eals/gmcl Molality cals/gmol 1*0 H MBA Solution Temperature Temperature l?o;>C. 25°C. 700 1.1954 .02885 -4,760 1*1611 .02622 -4,631 600 1.1760 .02923 -4,824 1.1457 .02693 -4,756 500 1.1558 ,02980 -4,917 1.1284 ,02798 -4,93? 400 1.1352 .03069 -5,065 1.1101 .02953 -5,217 300 1,1128 .03220 -5,314 1.0884 .03194 -5,643 200 1•0864 .03498 -5,771 I.0636 .03579 -6,323 100 1*o4s4 .04034 -6,657 1.0214 .04164 -7,356 50 1.0082 .04419 -7,292 .9712 .04493 -7,938 25 .9559 .04601 -7,591 .9001 .04630 10 ,8475 .04681 -7,725 .7515 .04688 5 .7164 .04699 -7,754 *5698 .04701 -8,412 35°C. 45° C. 700 1.1335 .02528 -4,771 1.1076 .02596 -5,222 600 1.1189 .02647 —4, 994 1.0937 ,02760 -5,552 500 1.1036 .02808 -5,298 1.0780 .02969 -5,973 400 1.0861 .03030 -5s7i8 1.0606 .63:37 -6,512 300 1.0657 .03342 I.O38O .03575 -7,192 200 1.0364 .03749 1.0061 -0,011 100 .9873 .04302 -8,119 ,9404 -8,880 50 •9w .04560 -8,604 .852J .04598 -9,249 2? .8i47 .04651 .7196 ,046o6 10 .6192 .04692 .4342 -1$I r% 55°c. 60° v • 700 1.0704 .02792 -5,975 1.0651 .02916 -6,432 600 1,0661 .02982 -6,382 1.0502 .03122 -6,806 500 1.0476 ^3220 . 1.0324 .03360 -7,410 400 1.0295 .03497 1.C105 -0,008 300 I.OO37 .03818 -8,170 .9817 .03929 -8,667 200 ,96% .04165 -8,913 .9367 .04229 -9,328 100 .8798 .04495 -9,620 .8386 .04526 -9,982 50 .7579 .04626 -9,900 .6958 .04636 -10,225 25 .5762 .04674 -10,002 .4806 ,04675 -10,312 41 Table 4 (cont’d) Partial Molai Heat cf Solution of Hydrogen Sulfide in Aqueous Monoethanclardne Solution Partial H0S in 2 In p Heat of H2S in 2ln p Heat of Pressure <_Soln. 3 T So In. Sc In. ~7T Soln. HE: Hg Molality cais/gmol Molality eals/gr;;ol 1.5 N KEA Solution Temperature Temperature i5°c. 25°C. 700 1.7677 .03034 -5,021 1.7447 .C894 -5,112 600 1.7662 ,03111 -5,13V 1.7260 .03007 -5.312 £00 I.7V28 .03206 -5,291 1.7051 .03156 -5,575 400 1.7183 .03344 -5,517 1.6822 .03356 -5,928 300 1.6902 .03549 -5,856 1.6539 .03627 -6,407 200 1.6550 .03663 -6,375 I.6165 .03986 -7,o4l 100 1.5969 .04326 -7,138 1.5487 .04422 -7,812 5c 1.5 93 .04587 -7,569 1.^33 .04632 -crl83 25 I.4399 .04699 -7,75V I.3V47 .04717 -8,332 10 1.2616 .04749 -7,837 I.1059 •o4y50 5 1.0565 .04761 -7,856 .8310 .04762 35°C. 45°C. 700 1.7057 .02927 -5,523 1.6653 .03096 —6, -28 600 1.6678 .03083 -5,818 1•6464 .03277 -6,592 500 1.6670 .03275 -6,180 1.6251 .03488 -7,017 400 1.6432 .03514 -6,631 1.5985 .03732 -7,507 300 1.6136 .03806 **•* e iSiS 1.5642 .04006 -8,058 200 1.5709 .-2,1:1; -7,831 1.5121 .04299 -8,648 100 1.4869 .04512 -8,5lV 1.4047 .04579 -9,212 5c i-. 3744 .04669 -6,810 ' 1.2567 .0469V -9,443 25 1.2166 .04730 -8,9 5 1.0457 .04739 -9,531 10 .8796 .04756 -8,975 .6178 .04756 -9 567 55° 0. 60° 0. 700 1.6196 .03334 -7,13V 1.5929 .03461 -7,634 600 1.5965 .03519 -7,532 1.5706 .03642 -0,034 500 1.573? .03725 -7,961 1.5441 -8,465 400 1.543V .03949 -8,448 1.5'LOl •m -8,921 300 1.5016 .04182 -6,950 1.4640 .04 57 -9,389 200 1.4366 ,04417 -9,V5-i 1.3903 .04463 -9 844 100 1,2966 .04627 -9,902 1.2293 •04645 -10,245 50 1.1003 .04711 -ic,081 I.0030 .04716 —J.0,402 25 .6194 .04742 -iC,i46 .6782 .04742 -10,459 42 Table 4 (cont'd) Partial Kolal Heat cf Solution of Hydrogen Sulfide in Aqueous Moncethanelamine Solution Partial KpS in 3in D Heat of HpS in ^ln p Heat of Pressure ‘Scln. 3 T So in. 'So In. $ T Scln. am Ilg Molality eals/gmol Molality cals/grol 2.0 H MEA Solution Temperature Temperature 15°C. 2 5°C. 700 2.4218 .03220 -5,314 2.3669 .03164 -5,590 600 2.3969 .03309 -5,461 2.3436 .03295 -5,820 5 0 -.3695 .03429 -5,658 2.3180 .03459 -6,110 4oo 2.3397 .03590 -5,9 3 2,2848 .03662 —6,469 300 2.3039 .03814 -6,294 2.2509 .03913 -6,913 200 2.2565 ,04099 -6,764 2.1987 .04211 -7,438 100 2.1730 .04463 -7 364 2.0980 .04531 -8,005 50 2.0714 ,04645 -7,665 1 9686 .04675 -8,259 25 1.9361 .04721 -7,791 1.7932 .04733 -8,360 10 1.6750 .04753 -7,843 1.4515 .04758 -8,406 5 1.3653 .04?64 -7,861 1.0725 .04765 -8,417 35°C. 45°C. 700 2.3129 .03267 -6,175 2.2531 .032-163 -6,965 600 2.2996 .03424 -6,462 2,2282 .03630 -7,3d 500 2,2629 .03614 -6,8]v 2.1980 .03614 -7,671 400 2.2308 .03629 -7,226 2.1617 .04-014 -8,074 300 1,1891 .04062 -7,662 2.1122 .04226 -8,501 200 2.1285 .04335 -8,180 2.0340 .04439 -8,930 100 2.0011 .04591 -b,663 1.8757 .04635 -9,324 50 1.8344 .04699 -8,867 1.6593 .04715 -9,485 25 1.6o57 .04741 -6,947 1.3601 *04?46 -9,547 10 1.1581 .04760 -8,982 .7759 .04759 -9,574 55°c. 60° 0, 700 2.1830 .03684 -7,884 2.14,05 .03794 -6.369 600 2.1542 .03641 -6,220 2.1024 .03944 -8,699 500 2.1194 .0WC7 -8.575 2.0716 .04094 -9,031 400 2.0755 .04179 -£,947 2.0228 .04249 -9,372 300 2.0153 .04352 -9,313 1.9547 .o44o4 -9,714 200 1.9195 .04519 -9,671 1.8462 .04550 -10,037 100 1.71*1 .04667 -9,987 1.6108 .04676 -10,319 5u 1.4328 .04726 -10,113 1.2895 .04729 -10,431 25 1.04-34 .o4?48 -10 16.' .8421 .04748 -10,472 % Table 4 (cont’d) Partial Kolal Heat of Soluti n of Hydrogen Sulfide in Aqueous Mcnoetl anolarrdne Solution Partial H S in ^ln p Heat of KpS in 3ln p Heat of Pressure Soln, 3 T Soln. Soln. 3T Soln. m Kg Holality cals/gaol Molality cals/gc.ol 3.0 N MEA Solution Toroerature Temperature i 5co. 25°c. 700 3.7388 .03533 -5,829 3.6509 .03571 -6,309 600 3.7048 .03640 -6,006 3.6161 -6.538 500 3.6662 .03766 -6,218 3.5769 .03847 -6,797 400 3.6214 .03920 -6,468 3.5286 ,U4012 -l\p87 300 3.5642 .04lo4 -6,771 3.^652 .04192 -7,418 200 3.4067 .04312 -7,116 30722 .04382 -7,742 100 3.3315 .04532 -7 478 3.1864 .04567 -8 068 % 3.1410 .04632 -7^43 2.9478 .04646 -8,207 25 2.8912 .04673 -7,710 2.6323 .04678 -8:264 10 2.4294 .04692 -7,742 2.0479 .04693 -8,291 5 1.9402 .04697 -7,750 1.4314 .04697 -a;197 35°C. 45° C. -7,000 3*%23 700 3.5637 .03873 _P-7,791 037 600 3.5173 .03842 -7,248 3.4013 .03996 500 3.4731 ,03984 -7,518 3*3508 ,04161 -8,370 wo 3.4188 .04136 -7,805 3.2864 .04-53 -8,555 300 3.3455 .04294 -8.104 3.1980 .04383 -8,816 200 3.2337 .04452 -8,401 3.1004 .04505 -9,063 100 3.0035 .04597 -8,675 2.7724 .04620 -9,293 50 2.7026 .04658 -8,789 2.3926 .04666 -9-386 25 2.3036 .04682 -8 835 1.8889 .04684 -9,423 10 1.5650 .04693 -8 857 .9595 .04692 -9,438 55° C. 600c. 700 3.3104 .04029 -8,622 3.2311 .04100 -9,04 600 3.2613 .04135 -8,848 3.1752 .04195 ,254 50c 3.2014 .04.42 -9,077 3.1090 .0429r —9,46 4oo 3.1334 .04345 -9, 98 3.0227 .04388 -9,678 300 3.0164 .04452 -9,527 2.9022 .04480 -9,880 200 2.8457 ,045% -9,736 2.7106 .04566 -10,070 100 2.4844 .04635 -9,920 2.3042 .04641 -10,236 50 2.0080 .04671 -9,995 1.7672 .04672 -10,305 25 1.3752 .04685 -10,025 1.0549 .04683 -10,329 44 Table 4 (eont’d) Partial Kclal Heat of Solution of Hydrogen Sulfide in Aqueous Honoethanclaisine Solution Partial II2S in 9 In_p Heat of I',S in Heat of Pressure So In. So In. Soln, o°c. 700 4.8152 ,04i46 -8,872 4.6849 .04189 -9,240 600 .04216 -9,022 4.6017 .04255 -9 384 500 4.6^62 .04288 -9,176 4.4990 .04319 -9,526 4CQ 4.5250 -9,327 4.3651 .04382 -9,665 300 4.3564 -9,471 4.1783 .04442 -9,798 200 4.0911 -9,6-7 3.8829 .04499 -9,922 100 3.5379 .04545 -9,727 3.26c4 .04548 -10,032 50 2.8262 .04569 -9,777 2.4782 .04572 -1C,085 25 1.9122 .04578 -9,797 1.4644 .04577 -10,095 Table 4 (cent*cl) Partial Molal Ileat of Solution of Hydrogen Sulfide in Aqueous Monoethanola; ine Solution Partial B0S in 9ln q. Heat of H0S in 9 In p Heat of Pressure c4^-'3oln. ^ mT So*Soln. In. 31 So In. ran Hg Molality cals/gmol Molality cals/gmol 5.0 R MBA Solution Temperature Temperature 15°C. 25°C. 700 7.5701 .03863 -6,374 7.2838 .03910 -6,907 600 7.4441 .03939 -6,500 7.2372 .03991 -7,051 500 7-3674 .04024 -6,640 7.1247 .04073 -7,196 400 7.2731 .04115 -6,790 7.0458 .04160 -7,349 300 7.1475 .04209 -6,940 6.9004 ,04246 -7,500 200 6.9587 .04306 -7,105 6.6794 .04329 -7,648 100 6.5855 -7,252 6.2334 .04406 -7,7[3 5o 6.1221 •M -7,317 5.6734 -7,C4l 0-5 5.5367 .040-51 -7,344- 4.9658 .04452 -7,865 10 4.5139 .04459 -7,357 3.7341 ,04459 -7,877 5 3.4996 ,04461 -7,361 2.5165 •04461 -7,880 35°C. 45° C. 700 7.0751 .03994 -7,537 6.8079 .04077 -8,201 600 6.9974 .04'69 -7,675 6.7146 .04139 4,326 500 6.9068 »o4i4i -7,814 6.6007 .04201 -8,450 4oo 6.7753 , 04 :l4 -7,952 6 * 454l .04261 -8,571 300 6.6054 .04286 -8,088 6.2508 .04320 .8,689 200 6.34/5 .04354 -8,217 5.9313 •8,800 100 5.0026 .04416 5.2855 -8,899 50 5.1257 .04443 4.4697 , c4' .45 -8.941 25 4.2703 .04453 -E!W4 3.4385 .04454 -8,959 10 2.7908 ,0446c -8,4l4 1.6699 4458 *( , 9w 55°G. 6o°C. O £ 700 6.4895 .04x48 *v, C>76 6.2672 .04x81 -9, 21 600 6.3806 .04199 <-,986 6.1.466 .04227 -9 323 6. 456 .04290 9.'94 5.9961 .04272 -9,422 16 6.0708 .04299 9^199 5.8014 .04315 -9.518 300 5.8287 .04346 9,300 5.5277 .04357 -9,611 200 5.4483 9,395 .04397 -9,697 100 4.6684 . ./‘i-'TJw 9,479 .7-334 .M32 -9,775 50 3.6"73 .04446 9,515 3.1412 .04446 -9,807 2-5 2.4504 .04453 9,530 1.7709 .04451 -9,818 46 Table 4 (ccnt’d) Partial Kolal Heat of Solution of Hydrogen Sulfide in Aqueous Mono.etbanolaiaino Solution Partial H2S in 2ln p Heat of HoS in 9ln_p Heat of Pressure 'Soln. "~cfT ScIn. Soln. d T Soln. ram ITg Molality cals/gmol Molality cals/giaol Temperature 100°C. Concentration of KEA Concentration of MEA 0,6 N 1.0 N 7 00 5484 .03494 -9,669 .6342 .11,042 600 53°5 .03665 -io,14o .8095 :&ic 500 5053 .01636 -10,616 .7663 .04215 400 4713 .04006 -11,064 .7075 .04325 •11,569 3C0 4220 .04167 -11,532 .6226 .04429 .12,257 poo 3375 .04322 -11,959 .4767 .04517 ■12,498 1.5 N 2.0 H 700 1.1981 04254 -11,771 1, .12,102 600 1.1527 -12,003 1, -12,(:69 500 1.0753 -12, 13 1, :§l .04492 .12,431 400 04419 -12,421 1, .2426 .04541 *12,5 4 .9835 1 300 • ‘ 5^9 t4558 -12,613 1 .0565 .04398 -12,724 200 .6280 046l4 -12,769 1 .7552 .04524 •12,519 3.0 N 4.0 N 700 2.153° ,04428 -12,251 3.0336 .04392 -12,154 600 2.0279 . 04466 2.85:8 .04419 -12,228 500 1.C706 .04503 -12!^6l 2.6255 .04445 -12,301 400 1.6636 .04538 -12,557 2,3285 .04470 -12,368 3)0 1.3705 . 04569 -12,643 1.9137 .04491 -12,427 200 .8088 .04588 -12,694 1.2537 .04504 -12,462 5.0 u 70C 3.9?iO .04311 ’1 ,929 oOC 3.7473 .04331 -11,984 500 3.4*2, .04350 ■12,038 400 3.0970 .04370 -12,092 300 2.5024 -12,1.33 200 1.6405 ■12,158 55 Discussions The calculated heat of solutions of hydrogen sulfide in aqueous aonoethanolamlne solutions has been found to vary considerably over the range of temperature, partial pressure of hydrogen sulfide, and amine concentration. The values of heat of solution vary from - 4,000 to - 13,000 calories per gram mole of dissolved hydrogen sulfide. The partial heat of solution is large and neg¬ ative as would be expected for solutions involving chemical association of solute and solvents. The partial heat of solution as defined becomes less negative with increasing partial pressure of hydrogen sulfide. The effect of temperature generally decreases the heat of solution of hydrogen sulfide, but shows a reversal trend at high partial pressure of hydrogen sulfide. The heats of solutions of hydrogen sulfide in this work and of carbon dioxide as determined by Krichevski and Ilinskaya (9) show similar influences of partial pressure of the acid gas and amine concentration. Since the effects of tenperature were not determined by the latter, no comp¬ arison can be made. It can only be stated that the experimental heat of solution data of carbon dioxide and hydrogen sulfide as reported by Bottoms (2) are of the same order of magnitude as those 56 calculated by author* Bottoms reported only one value for the heat of solution of hydrogen sulfide in aqueous ethanol- amine solution. Curves of the heat of solution as a function of partial pressure of hydrogen sulfide indicates that the heat of solution becomes independent of partial pressure at high partial pressures of hydrogen sulfide for low concentrations of mono ethanelanine in water. For high concentrations of monoethanclamine in water no such trend is evident at the partial pressures of hydrogen sulfide considered. The “levelling of” ©f the heat of solution seems to be the result of near complete reaction between hydrogen sulfide and monoe thanolamine at high partial pressure of hydrogen sulfide when dilute solutions of monoethane 1 arcine in water are involved. The relationship has been developed to describe the solu¬ bility of hydrogen sulfide in aqueous moncethanolamine solu¬ tion as reported by Biegger, Tartar and Lingafelder (15)• The absolute average deviation of the solubilities of hydrogen sulfide obtained by the calculations of this work and that of Riegger, Tartar and Lingafelder is 2.2 per cent. The solubility data of Leibush and Shnerson (10) is represent¬ ed by the same relations to an accuracy of about 12 per cent absolute average deviation and maximum deviation of 21.2 57 per cent. It is evident that the experimental data of the two sources do not agree in the same general concentration range. On the basis of the inner consistency of the solu¬ bility data and the extensiveness of the data, the experi¬ mental values of megger, Tartar and Lingafelder (1?) were used in the above calculations. The complexity of the functions describing the solubility of hydrogen sulfide has prevented the development of a relat¬ ing errors in the solubility predictions to the resulting deviations in the partial heats of solution of hydrogen sulfide. The sources of the deviations reported above is reflected in Figures 1, 2 and 3 where the variation of K^, the hypo¬ thetical chemical equilibrium constant, with partial pressure is approximated by a straight line on a log-log plot. These straight lines clearly do not represent the data precisely over the entire pressure range. Although the representation of the values appear at first hand to be most inaccurate at high pressures, the calculated and experi¬ mental solubilities show their greatest discrepancies at low pressures as Table 3 indicates. When the value cf is large, the error in the representation of Xx causes snail deviations in value of Ts/b cf equation (19). However, whon Kx is small, k/b of equation (26) becomes very sensitive 58 Table 5 Partial Molal Heat of Solution of Hydrogen Sulfide in Aqueous Koncethanolamine Solution Partial in *^ln 9 Heat of I^S in 3ln p Haat of Pressure ‘'So In. 3T So In. ‘"Scln. So In. mm Hg Molality cals/gmol Molality cals/gmol 2.0 N MBA Solution Temperature Temoerature i5°c. 25°C. 700 2.4099 *031.74 -5,237 2.3516 .03087 -5,452 600 2.3027 .03242 -5,350 2.3347 .03207 -5,5o4 500 2.3556 .03340 -5,511 2.3 85 *03351 -5,918 400 2.3234 .03468 -5,722 2.2734 .03528 -6,241 300 2.2851 .03710 -6,122 2.2377 .03744 -6,612 200 2.2334 .03661 -6,371 2.1824 .03995 -7,o56 10c 2.142 .04145 -6,t40 2.0751 .04260 -7,524 50 2.0247 .04328 -7,142 1,9366 .iMtU -7,735 25 ..8707 .04406 -7,270 1.7580 .04426 -7,017 10 1.5717 .04446 -7,336 '. 3(' !6 .04447 -7,154 5 1.2393 .-4 52 -7,346 .9727 .04453 -7,664 35uo. 45° C. 700 2.3097 .03134 -5,914 2.2600 .03261 -6,560 600 2.2867 .03 55 -6,143 2.-268 .03415 -6,869 500 2.2594 .03445 -6,501 2.2068 .03579 -7,199 400 2.2 67 .03632 -6,854 2.1706 .03763 -7,569 300 2.1843 .03646 -7,258 2.1229 .03957 -7,960 200 2.1214 .04076 -7,692 2.0492 .04153 -8,354 100 1.9939 .o4301 -e!ii6 i.c-948 -8,718 50 1.8236 .04394 -8,292 1.6863 ■m -8,865 25 1.5907 .04433 -0,366 1.3972 .04436 -8,923 10 1.1352 ,O4449 -8^396 .8$47 .04449 -8,949 55° c. 60° G. 700 2.2029 .03425 -7,329 2,1838 .03490 -7,698 600 2.1759 .03573 -7,646 2.1513 .03634 -8,015 5T00 2.1519 .03734 -7,99t 2.1170 . 0376*2 -8,342 400 2.1017 .03891 *■8.327 2.0737 .03938 -8,708 300 2.O462 .04056. -6,600 2.0141 ,04090 -9,021 200 1.9577 .04216 -9,022 1,9188 .04238 -9,348 100 1.7679 .04359 -9,32.8 1.7x36 .04360 -9,635 50 1.5089 .04417 -9,452 1A338 .04419 -9,747 25 1.1453 .04438 -9,497 1,0440 .04438 -9,789 59 tc deviations in which producing the maximum deviations in the solubility values. Figures 4, and 7 are graphical relationships used to determine the mathematical relationship representing K^. as a function of temperature, pressure and concentration. Although the experimental heats of solution data are not available to check the calculated values, the sensitivity of the method can be evaluated by assuming a slightly differm¬ ent equation and comparing the calculated values using two relationships. If K* =9.56 *IO6X1O~0.0121T H0.00775T - 4.4-7 pC.625tr°-3°9 (lf2) be taken rather than the function given by equation (32), the heats of solutions can be recalculated. The heat of solu¬ tion together with the solubility data are tabulated in Table 5 and may be compared with the values of Table 3 and 4. The maximum deviation of the heat of solution is seen to be 10 per cent. While many questions remain unanswered in this work, calculations demonstrate that the heat of solution of hydrogen sulfide in aqueous aonoethanolamine solution is extremely sensitive to variations in the amine concentra¬ tion, the partial pressure of the equilibrium hydrogen sulfide, and to the temperature. BIBLIOGRAPHY 1 Atadan, E. M., Ph, D. Thesiis, University 'f Tennessee. Aug. (195^) 2 Bottoms, R. R., Chem. & Met., 38, 465 (1931) 3 Canjar, L. N. & Edmeister, W. C., Applied Thermo¬ dynamics. Gh. E. Progress Symposium Series, 4^, Ho.7 - 73 (1953) 4 Dolezalek, F. & Schluze, A., phy. Chem., M. ^5 (1913) 5 Gregory, L. B. & Sohartaann, W. G., Ind. Eng. Chem., 514 (1937) 6 Gailer, J. W., Goodri lge, F. & Atkins, D. E.. Trans. Inst. Chem. Eng. (London), ^2, S-2 - 5 (1954) 7 Hildebrand, J. E. & Scott, R. L,, The Solubility of Nonelectrolytes, pp 177 (1958) Reinhold Publish¬ ing Co., N. Y. o f International Critical Tables Vol. 3» PP 259 9 Krichevskil, I. R* & Ilinskaya, A. A., J. Phys* Chem. (USSR), 1£, 621 (1945) 10 Leibush, A. G. & Shnerson, A. L., J. Auolied Chem. (USSR), 2^, No.2, 145 (1950) li Lyudkcvskaya, M. A. & Leibush, A. G., Ibid., 22 No.6 558 (1949) 12 Mason, J, W. & Dodge, B. F., Trans. A. I, Ci. E., 27 (1936) 13 Papadopoulos, A., Pigf rd, R, L. & Friend, L., Applied Thermodynamics, Ch. E. P. Symp, Series, 49, No.7 119 (1953) lb Perry, J. E., Chem# Eng. Iiandb v:k, pp 675 15 Rigger, B., Tartar, o. & Lingafelder, E., J. Am. Chem. Sec., 66 , 2024 (1944) 16 Willers, Fr. A., Practical Analysis (Translated by R. T» Beyer), pp 9°, Dover Publications, N. Y. (1947)