3098
Ind. Eng. Chem. Res. 1998, 37, 3098-3104
Correlation and Prediction of the Solubility of CO2 and H2S in an Aqueous Solution of 2-Piperidineethanol and Sulfolane Yi-Gui Li† and Alan E. Mather* Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2G6
The simplified Clegg-Pitzer equations are used to correlate the solubility data of CO2 in the 2-PE (2-piperidineethanol) (45 wt %)-TMS (sulfolane) (40 wt %)-H2O (15 wt %) system at 25, 40, 70, 100, and 130 °C and the solubility data of H2S in the 2-PE (45 and 55 wt %)-TMS (40 and 10 wt %)-H2O (15 and 35 wt %) systems at 40 and 100 °C. The interaction parameters thus determined can be used to predict the solubility data for the CO2-2-PE (55 wt %)-TMS (10 wt %)-H2O (35 wt %) system at 40 and 100 °C and also for the quinary CO2-H2S-2-PETMS-H2O system without any additional adjustable parameters. The equations have been proven again to be of use for aqueous solutions containing mixed physical and chemical solvents and ionic species with chemical equilibria. Introduction Mixed solvents, which comprise physical and chemical solvents, have been proposed for use in selective absorption processes, since they possess the advantages of both physical solvents and chemical solvents. 2-Piperidineethanol (2-PE; CAS [1484-84-0]), being a chemical solvent and a sterically hindered amine, has a low tendency to form carbamates with CO2 due to the bulkiness of the substituent attached to the amine group (Sartori and Savage, 1983). Therefore, it has a high capacity for the CO2 acid gas. Also it has a higher reaction rate with CO2 than methyldiethanolamine (MDEA) (Shen et al., 1991). On the other side, sulfolane (tetramethylene sulfone (TMS) or tetrahydrothiophene 1,1-dioxide (CAS [126-33-0])) is a readily available and stable physical solvent, which has an especially high capacity for CO2 and H2S. So, the 2-PE-TMS-H2O ternary mixed-solvent system is a promising one for gas purification processes. The solubility data for CO2 and H2S in mixed solvents at various temperatures and compositions are required for acid gas purification process design. Jou et al. (1998) measured the solubility of CO2 and H2S in 2-PE (45 wt %)-TMS (40 wt %)-H2O (15 wt %) system at 40 and 100 °C. Additional data for CO2 in the same solvent were obtained at 25, 70, and 130 °C. Data were also obtained for mixtures of H2S and CO2 in this solution at 40 and 100 °C. Lal et al. (1998) measured the solubility of CO2 and H2S and their mixtures in the 2-PE (55 wt %)-TMS (10 wt %)-H2O (35 wt %) system at 40 and 100 °C. The molar compositions of these two solvents are as follows:
wt % mol %
2-PE
TMS
H2O
2-PE
TMS
H2O
45.0 23.0
40.0 22.0
15.0 55.0
55.0 17.4
10.0 3.4
35.0 79.2
* To whom correspondence should be addressed. Telephone: +1-403-492-3957. Fax: +1-403-492-2881. E-mail:
[email protected]. † Permanent address: Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.
Recently, Li and Mather (1994) used the Clegg-Pitzer (Clegg and Pitzer, 1992) equations to correlate the solubility of CO2 in MDEA-H2O and MEA-H2O systems (MEA, monoethanolamine) and to predict those for the MDEA-MEA-CO2-H2O system. Qian et al. (1995) used the same equations to correlate the solubility of CO2 and H2S in the MDEA-TMS-H2O system, respectively, and to predict those for the CO2-H2S-MDEATMS-H2O system. In this paper, we use the CleggPitzer equations again to correlate the 2-PE-TMSCO2-H2O and 2-PE-TMS-H2S-H2O systems and to predict the 2-PE-TMS-CO2-H2S-H2O system. Thermodynamic Framework Chemical Equilibria. In the aqueous phase for the 2-PE-TMS-CO2-H2S-H2O system, the following chemical equilibria are involved: K1
CO2 + 2H2O 798 H3O+ + HCO3K2
H2S + H2O 798 H3O+ + HSK3
2-PEH+ + H2O 798 H3O+ + 2-PE
(1a) (2a) (3a)
The thermodynamic equilibrium constants used in this work are based on the mole fraction scale. The temperature dependence of the equilibrium constants is represented by the following function:
ln K ) C1 + (C2/T) + C3 ln T + C4T
(1)
The coefficients C1-C4 for reactions (1a)-(3a) are summarized in Table 1. The Henry’s constant has the unit of pascals. Its temperature dependence is expressed by the same functional form as shown in eq 1. Standard States. In this work, the standard states are taken as the same as those in our previous paper
S0888-5885(97)00780-X CCC: $15.00 © 1998 American Chemical Society Published on Web 05/23/1998
Ind. Eng. Chem. Res., Vol. 37, No. 8, 1998 3099 Table 1. Temperature Dependence of the Equilibrium Constants for Reactions (1a)-(3a) and Henry’s Constants for CO2 and H2S
ln H or ln K ) C1 + C2/T + C3 ln T + C4T reaction
compd
C1
C2
C3
C4
temp range ( °C)
source
(1a) (2a) (3a) HCO2 HH2S
CO2 H2S 2-PE CO2 H2S
231.465 241.582 -1.623615 170.7126 358.138
-12092.1 -12995.4 -6474.585 -8477.711 -13236.8
-36.7816 -33.5471 0.0 -21.95743 -55.0551
0.0 0.0 0.0 0.005781 0.059565
0-225 0-150 15-60 0-100 0-150
a a b c a
a
Edwards et al. (1978). b Xu et al. (1992a). c Chen et al. (1979).
Table 2. Temperature Dependence of the Density for Pure Solvents solvent
MW
H2O TMS 2-PE a
expression 10-5t
10-6t2
d ) 0.999382 + 7.208 × - 7.28491 × + 2.65177 × d ) 1.19003 - 8.7685 × 10-4t - 0.096 × 100-7t2 -3 d ) 1.01557 - 0.767533 × 10 t
18.02 120.17 129.20
10-8t3
temp range ( °C)
source
30-75 30-125 30-85
a b c
Littel et al. (1992). b Casteel and Sears (1974). c Xu et al. (1992a).
Table 3. Temperature Dependence of the Density for Mixed Solvents composition (wt %)
a
2-PE
H2O
TMS
expression
temp range ( °C)
source
45.0 55.0
15.0 35.0
40.0 10.0
d ) 1.124264 - 7.7417 × 10-4t - 7.2736 × 10-7t2 d ) 1.058462 - 6.6932 × 10-4t - 1.11644 × 10-6t2
20-85 20-85
a a
Xu et al. (1992b).
Table 4. Temperature Dependence of the Dielectric Constants for Pure Solvents solvent
expression
temp range ( °C)
source
H2O
D ) 78.54[1 - 4.579 × 10-3(t - 25) + 1.19 × 10-5(t - 25)2 - 2.8 × 10-8(t - 25)3]
0-100
a
2-PEd
D ) 24.74 + 8989.3
TMS
D ) -20.24 +
1 (T1 - 273.15 )
2.2654 × 104 1.14335 × 106 T T2
a Maryott and Smith (1951). b Austgen et al. (1991). c Casteel and Sears (1974). as that of MDEA.
d
25-50
b
30-125
c
Dielectric constant of 2-PE fixed at the same value
Table 5. Fitted Values of Interaction Parameters between Solvents
Ann′ ) a + (b/T) Ann′ n-n′
Ann′a
a
b (K)
2-PE-H2O H2O-2-PE TMS-H2O H2O-TMS
A12b A21b
-0.1691 -1.6244 0.8056 -0.8146
0 0 157.94 840.20
A32 A23
40 °C
100 °C
source
1.2288 1.4370
c c d d
-0.1691 -1.6244 1.310 1.868
a 1 ) 2-PE; 2 ) H O; 3 ) TMS. bA c 2 nn′ of the 2-PE-H2O system fixed at the same values as the MDEA-H2O system. Li and Mather (1994). d Qian et al. (1995).
(Qian et al., 1995). Water, 2-PE, and TMS are all treated as solvents with the pure liquid as their standard states, while the ionic species (2-PEH+, HCO3-, and HS-) and the neutral species (CO2 and H2S) are treated as solutes with the infinitely dilute aqueous solution as their standard states. For simplicity, in this work, we neglect the ionic species of CO32- and S2- and also the neutral species of CO2 and H2S, because their concentrations are very low compared with the other species dissolved in the mixed solvents. We also neglect the nonideality of the gas phase. So, our calculation is limited to the low pressure range (0.1-2000 kPa) and the total acid gas loading (CO2 + H2S) below 0.9 (mol of acid gases/mol of 2-PE). When unreacted amine is
present, the concentration of the molecular solute species is very low compared with the other species (Qian et al., 1995). If we consider the ionic species CO32- and S2-, we must consider as well the species OH- and H+. This makes the calculations more complicated, and from our previous work on amine systems, we found that the concentration of these ions is very low and that the correlation is not improved by the addition of these species in the material balances and activity coefficient calculations. Thermodynamic Expression. In this paper, we continue to use the Clegg-Pitzer equations. For the 2-PE-TMS-CO2-H2S-H2O quinary system, the activity coefficient expressions for neutral solvent (2-PE)
3100 Ind. Eng. Chem. Res., Vol. 37, No. 8, 1998 Table 6. Fitted Values of Interaction Parameters for the 2-PE-CO2-TMS-H2O Systema
B (or W) ) a + b/T B (or W) BMX W1,MX W2,MX W3,MX a
a
b, K
25 °C
40 °C
70 °C
100 °C
130 °C
-269.3151 -7.351734 5.860342 31.36401
81322.32 930.4011 -906.3395 -8005.014
3.44128 -4.231153 2.820464 4.515064
-9.623853 -4.38063 2.966075 5.801138
-32.32745 -4.64038 3.219107 8.035981
-51.38046 -4.858364 3.431454 9.911476
-67.59785 -5.043905 3.612197 11.50784
Subscripts: 1 ) 2-PE; 2 ) H2O; 3 ) TMS; M ) 2-PEH+; X ) HCO3-.
and ionic species (2-PEH+) are as follows:
2AXIX3/2 ln γ1 ) - xMxXBMX exp(-RIX1/2) 1 + FIX1/2 xMxYBMY exp(-RIX1/2) + A12(1 - 2x1)x22 + 2A21x1x2(1 - x1) + A13(1 - 2x1)x32 + 2A31x1x3(1 - x1) - 2x2x3(A23x3 + A32x2) + (1 - x1)xI(FXW1,MX + FYW1,MY) - x2xI(FXW2,MX + FYW2,MY) - x3xI(FXW3,MX + FYW3,MY) (2)
[
ln γ*M ) -zM2Ax
( )
2IX IX1/2 1 - 2 zM
2 ln(1 + FIX1/2) + F 1 + FIX1/2
]
+
xXBMXg(RIX1/2) + xYBMYg(RIX1/2) - xM(xXBMY +
[
(
)
]
z2M zM2g(RIX1/2) xYBMY) + 1exp(-RIX1/2) 2IX 2IX 2x1x2(A12x2 + A21x1) - 2x1x3(A13x3 + A31x1) 2x2x3(A23x3 + A32x2) + x1(1 - xI)(FXW1,MX + FYW1,MY) + x2(1 - xI)(FXW2,MX + FYW2,MY) + x3(1 - xI)(FXW3,MX + FYW3,MY) (3)
Figure 1. Solubility of CO2 in 45 wt % 2-PE-40 wt % TMS aqueous solutions at 25, 40, 70, 100, and 130 °C.
Here the subscripts 1, 2, 3, M, X, and Y represent 2-PE, H2O, TMS, 2-PEH+, HCO3-, and HS-, respectively. The definition of FX, FY, and xI are as follows:
2xX xI
FX )
2xY xI
FY )
xI ) xM + xX + xY ) 1 - x1 - x2 - x3
(4) (5)
The x’s are the mole fractions in the equilibrated liquid phase. The expressions for γ2 and γ3 are similar to γ1 and γ*X and γ*Y are similar to γ*M. So they are not introduced here again. The nomenclature for the other symbols in the above expressions is the same as that in our previous papers (Li and Mather, 1994; Qian et al., 1995). The temperature dependence of the density of the pure and mixed solvents and the dielectric constant of the pure solvents are listed in Tables 2-4, respectively. Because the dielectric constant of 2-PE is not available, we assume that it is the same as that of MDEA. The calculation methods for the Debye-Hu¨ckel parameter (AX), the closest approach parameter (F), the Pitzer function (g(RIX1/2)), and the dielectric constant for mixed solvents are the same as those in our previous paper (Qian et al., 1995) and are not repeated here.
Figure 2. Solubility of CO2 in 55 wt % 2-PE-10 wt % TMS aqueous solutions at 40 and 100 °C.
Data Regression: Determining Interaction Parameters Binary Systems. For the TMS-H2O system, the Margules interaction parameters (A23 and A32) have been regressed in our previous paper (Qian et al., 1995). Because there is no information for the 2-PE-H2O and 2-PE-TMS binary systems, it is assumed that the nonideality in a 2-PE-H2O solution is the same as that in an MDEA-H2O solution. So, we fix the A12 and A21
Ind. Eng. Chem. Res., Vol. 37, No. 8, 1998 3101 Table 7. Fitted Values of Interaction Parameters for the 2-PE-H2S-TMS-H2O Systema t (°C) BMY W1,MY W2,MY W3,MY
40
100
70.90994 -5.392739 8.457516 14.37344
4.063804 -4.255236 6.219024 13.82374
a Subscripts: 1 ) 2-PE; 2 ) H O; 3 ) TMS; M ) 2-PEH+; Y ) 2 HS-.
Figure 5. Comparison of predicted and experimentally measured values of the CO2 and H2S equilibrium partial pressures over a 45 wt % 2-PE-40 wt % TMS aqueous solution at 40 °C.
Figure 3. Solubility of H2S in 45 wt % 2-PE-40 wt % TMS aqueous solutions at 40 and 100 °C.
Figure 6. Comparison of predicted and experimentally measured values of the CO2 and H2S equilibrium partial pressures over 45 wt % 2-PE-40 wt % TMS aqueous solution at 100 °C.
Figure 4. Solubility of H2S in 55 wt % 2-PE-10 wt % TMS aqueous solutions at 40 and 100 °C.
values for 2-PE-H2O at the same values as those in MDEA-H2O. Because of the structural similarity, we assume the 2-PE and TMS form to be an ideal solution. So, the A13 and A31 values are set to zero. All the Margules interaction parameters for neutral solvents used in this work are listed in Table 5. Quaternary Systems. The experimental data for the 2-PE-CO2-H2O and 2-PE-H2S-H2O ternary systems are not available, and the TMS-CO2-H2O ternary
systems do not contain the interactions between neutral solvent and ionic solute. So, we have to use the experimental data for 2-PE-TMS-CO2-H2O and 2-PETMS-H2S-H2O quaternary systems to regress the interaction parameters directly. In our calculation, we approximately assume that all the dissolved CO2 and H2S is completely converted into HCO3- and HS- ions, which greatly simplifies our computation. So, the calculations in this paper are simpler than those in our previous paper (Qian et al., 1995). From reactions (1a) and (3a), we get
pCO2 )
HCO2K3xMγ* MxXγ* X K1x1γ1x2γ2
From reactions (2a) and (3a), we get
(6)
3102 Ind. Eng. Chem. Res., Vol. 37, No. 8, 1998 Table 8. Average Deviation for Correlation and Prediction of VLE Data in Various Systems and Sources of Experimental Data δ (%)a system
no. of data points
temp (°C)
solvent compound
corr.
7 14 10 12 7 7 15 16 23 14 19 13 15 15 17
25 40 70 100 130 40 100 40 100 40
45 wt % 2-PE 45 wt % 2-PE 45 wt % 2-PE 45 wt % 2-PE 45 wt % 2-PE 55 wt % 2-PE 55 wt % 2-PE 45 and 55 wt % 2-PE 45 and 55 wt % 2-PE 45 wt % 2-PE
22.8 16.9 25.2 19.7 29.9
100
45 wt % 2-PE
100
55 wt % 2-PE
2-PE-CO2-TMS-H2O
2-PE-CO2-TMS-H2O 2-PE-H2S-TMS-H2O 2-PE-CO2-H2S-TMS-H2O
aδ
pred.
21.9 30.1 12.3 11.5 24.9 (CO2) 14.8 (H2S) 27.5 (CO2) 16.3 (H2S) 16.1 (CO2) 20.0 (H2S)
figure
source
1 1 1 1 1 2 2 3, 4 3, 4 5 5 6 6 7, 8 7, 9
b b b b b c c b b b b b b c c
n ) {(1/2)∑i)1 |pi,cal - pi,exp|/pi,exp} × 100%. b Jou et al. (1998). c Lal et al. (1998).
pH2S )
HH2SK3xMγ* MxYγ* Y K2x1γ1
(7)
In most cases, the objective function used for the regression is
∑|pcal - pexp|/pexp} × 100%
F){
(8)
When the minimum objective function cannot be found, the following objective function, which was suggested by Weiland et al. (1993), is also used:
F){
∑(pcal - pexp)2/pcalpexp} × 100%
(9)
In this work, we use the experimental solubility data of CO2 (in a 45 wt % 2-PE-40 wt % TMS aqueous solution at 25, 40, 70, 100, and 130 °C) (Jou et al., 1998) to regress the four interaction parameters for MX(2PEH+HCO3-) (BMX, W1,MX, W2,MX, and W3,MX) and their temperature coefficients (a and b). The parameters thus obtained are listed in Table 6, and the correlation results are shown in Figure 1. We use these regressed parameters to predict the solubility of CO2 (in a 55 wt % 2-PE-35 wt % TMS aqueous solution at 40 and 100 °C) (Lal et al., 1998). The prediction results are shown in Figure 2. We also use the experimental solubility data of H2S (in 45 wt % 2-PE-40 wt % TMS aqueous and 55 wt % 2-PE-35 wt % TMS aqueous solutions at 40 and 100 °C) (Jou et al., 1998; Lal et al., 1998) to regress the other four interaction parameters for MY(2-PEH+HS-) (BMY, W1,MY, W2,MY, and W3,MY). The parameters thus obtained are listed in Table 7, and the correlation results are shown in Figures 3 and 4. The average relative deviations of the partial pressure of acid gases for correlation and prediction are listed in Table 8. Prediction of CO2 and H2S Solubility in Acid Gas Mixtures for Mixed-Solvent (2-PE-TMS-CO2-H2S-H2O) Quinary Systems We use the above-regressed interaction parameters, which are obtained from single acid gas systems, to predict the CO2 and H2S solubility in acid gas mixtures for the quinary mixed-solvent systems (45 wt % 2-PE40 wt % TMS aqueous at 40 and 100 °C and 55 wt % 2-PE-10 wt % TMS aqueous only at 100 °C). The
Figure 7. Comparison of predicted and experimentally measured values of the CO2 and H2S equilibrium partial pressures over a 55 wt % 2-PE-10 wt % TMS aqueous solution at 100 °C.
prediction results are shown in Figures 5-7. The relative deviations for pCO2 and pH2S are also listed in Table 8. Figures 8 and 9 also show the modeling results and experimental results for the 55 wt % 2-PE system at 100 °C in the presence of both CO2 and H2S. From these figures, it can be seen that the agreement between predicted and experimental partial pressures is acceptable. Discussion and Conclusions The model used here has some shortcomings. Although it was possible to predict data for the 55 wt % 2-PE solution, this concentration is not very different from the 45 wt % 2-PE solution from which the parameters were obtained. The situation with TMS is more satisfactory as the data range is from 2.5 to 23.3 mol of H2O/mol of TMS. There is a need for data at other 2-PE concentrations. The equilibrium constant for the protonation of 2-PE, K3, is available over a narrow range of temperature and had to be extrapolated in this work. Values at higher temperatures would be useful to confirm the extrapolation. The assumption
Ind. Eng. Chem. Res., Vol. 37, No. 8, 1998 3103
Acknowledgment This work was supported financially by the Natural Sciences and Engineering Research Council of Canada (NSERC). Nomenclature
Figure 8. Comparison of predicted results with experimental results for CO2 in a 55 wt % 2-PE-10 wt % TMS aqueous solution in the presence of H2S at 100 °C.
A ) interaction parameter between and among neutral molecules AX ) Debye-Hu¨ckel parameter on a mole fraction basis a, b ) temperature coefficients in Table 6 B ) interaction parameter between ions C1-C4 ) coefficients of eq 1 d ) density, g/mL D ) dielectric constant F ) ionic fraction F ) objective function H ) Henry’s constant, Pa IX ) ionic strength on a mole fraction basis K ) thermodynamic chemical equilibrium constant p ) partial pressure, Pa or kPa as noted t ) temperature, °C T ) absolute temperature, K W ) interaction parameter between and among neutral and ionic species x ) liquid-phase mole fraction based on the true species, molecular and ionic z ) valence of an ion Greek Letters R ) Pitzer universal constant in eq 7 R ) CO2 or H2S loading in the liquid phase, mol of CO2 or H2S/mol of 2-PE γ ) activity coefficient δ ) average relative deviation, % F ) closest approach parameter Superscript * ) unsymmetrical convention Subscripts
Figure 9. Comparison of predicted results with experimental results for H2S in a 55 wt % 2-PE-10 wt % TMS aqueous solution in the presence of CO2 at 100 °C.
that the interactions in the 2-PE-H2O system are the same as those in the MDEA-H2O system is another weakness of the model. Data for activity coefficients in the binary system 2-PE-H2O are needed for improvement of the model. Other data, which would be useful although not strictly necessary, would be acid gas solubility in the ternary systems 2-PE-CO2-H2O and 2-PE-H2S-H2O to confirm the parameters obtained from the data for the quaternary systems. From our previous work on modeling of acid gas equilibria, the effect of uncertainty in the dielectric constant and density of the solution is minor on the prediction of the solubility. This work has proven again that the Clegg-Pitzer equations are capable of predicting the solubility of the acid gas mixture in mixed physical and chemical organic solvent systems containing ionic species without any additional adjustable parameters.
1 ) H2O 2 ) 2-PE 3 ) TMS M ) 2-PEH+ X ) HCO3Y ) HScal ) calculated value corr ) correlation exp ) experimental value pred ) prediction
Literature Cited Austgen, D. M.; Rochelle, G. T.; Chen, C.-C. Model of VaporLiquid Equilibria for Aqueous Acid Gas-Alkanolamine Systems. 2. Representation of H2S and CO2 Solubility in Aqueous MDEA and CO2 Solubility in Aqueous Mixtures of MDEA with MEA or DEA. Ind. Eng. Chem. Res. 1991, 30, 543. Casteel, J. F.; Sears, P. G. Dielectric Constants, Viscosities, and Related Physical Properties of 10 Liquid Sulfoxides and Sulfones at Several Temperatures. J. Chem. Eng. Data 1974, 19, 196. Chen, C.-C.; Britt, H. I.; Boston, J. F.; Evans, L. B. Extension and Application of the Pitzer Equation for Vapor-Liquid Equilibrium of Aqueous Electrolyte Systems with Molecular Solutes. AIChE J. 1979, 25, 820. Clegg, S. L.; Pitzer, K. S. Thermodynamics of Multicomponent, Miscible, Ionic Solutions: Generalized Equations for Symmetrical Electrolytes. J. Phys. Chem. 1992, 96, 3513. Edwards, T. J.; Maurer, G.; Newman, J.; Prausnitz, J. M. VaporLiquid Equilibria in Multicomponent Aqueous Solutions of Volatile Weak Electrolytes. AIChE J. 1978, 24, 966.
3104 Ind. Eng. Chem. Res., Vol. 37, No. 8, 1998 Jou, F.-Y.; Otto, F. D.; Mather, A. E. Solubility of H2S, CO2 and their Mixtures in an Aqueous Solution of 2-Piperidineethanol and Sulfolane. J. Chem. Eng. Data 1998, 43, 409-412. Lal, D.; Otto, F. D.; Mather, A. E. Solubility of Acid Gases in a Mixed Solvent. Can. J. Chem. Eng. 1998, accepted. Li, Y.-G.; Mather, A. E. The Correlation and Prediction of the Solubility of Carbon Dioxide in a Mixed Alkanolamine Solution. Ind. Eng. Chem. Res. 1994, 33, 2006. Littel, R.J.; Versteeg, G. F.; van Swaaij, W. P. M. Solubility and Diffusivity Data for the Absorption of COS, CO2 and N2O in Amine Solutions. J. Chem. Eng. Data 1992, 37, 49. Maryott, A. A.; Smith, E. R. Table of Dielectric Constants of Pure Liquids; NBS Circular 514; U.S. Government Printing Office: Washington, DC, 1951. Qian, W. M.; Li, Y.-G.; Mather, A. E. Correlation and Prediction of the Solubility of CO2 and H2S in an Aqueous Solution of Methyldiethanolamine and Sulfolane. Ind. Eng. Chem. Res. 1995, 34, 2545. Sartori, G.; Savage, D. W. Sterically Hindered Amines for CO2 Removal from Gases. Ind. Eng. Chem. Fundam. 1983, 22, 239.
Shen, K.-P.; Li, M.-H.; Yih, S.-M. Kinetics of Carbon Dioxide Reaction with Sterically Hindered 2-Piperidineethanol Aqueous Solutions. Ind. Eng. Chem. Res. 1991, 30, 1811. Weiland, R. H.; Chakravarty, T.; Mather, A. E. Solubility of Carbon Dioxide and Hydrogen Sulfide in Aqueous Alkanolamines. Ind. Eng. Chem. Res. 1993, 32, 1419. Xu, S.; Wang, Y.-W.; Otto, F. D.; Mather, A. E. Physicochemical Properties of 2-Piperidineethanol and its Aqueous Solutions. J. Chem. Eng. Data 1992a, 37, 407. Xu, S.; Wang, Y.-W.; Otto, F. D.; Mather, A. E. The Physicochemical Properties of the Mixed Solvent of 2-Piperidineethanol, Sulfolane and Water. J. Chem. Technol. Biotechnol. 1992b, 56, 309.
Received for review November 10, 1997 Revised manuscript received March 18, 1998 Accepted March 25, 1998 IE970780T
