Density of Water (1) + Diethanolamine (2) + CO2 (3) and Water (1) + N

May 9, 2012 - Density of Water (1) + Diethanolamine (2) + CO2 (3) and Water (1) + ... Journal of Chemical & Engineering Data 2017 62 (9), 2761-2769 ...
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Density of Water (1) + Diethanolamine (2) + CO2 (3) and Water (1) + N-Methyldiethanolamine (2) + CO2 (3) from (298.15 to 423.15) K Jingyi Han,†,‡ Jing Jin,‡ Dag A. Eimer,†,‡ and Morten C. Melaaen*,†,‡ †

Tel-Tek, 3918 Porsgrunn, Norway Telemark University College, 3901 Porsgrunn, Norway

‡

ABSTRACT: Densities in liquid solutions of water + diethanolamine (DEA) and water + N-methyldiethanolamine (MDEA) have been measured at temperatures from (298.15 to 423.15) K. The mass fraction of amine ranged from 0.3 to 1.0. Excess molar volumes of the binary system were derived and correlated by a fourth order Redlich−Kister equation and a second polynomial function with respect to the temperature. Densities in liquid solutions of water + DEA + CO2 and water + MDEA + CO2 have been measured at temperatures from (298.15 to 423.15) K. The mass fraction of amine in water was 0.3 and 0.4. The CO2 loading ranged from 0.1 to 0.5. Molar volumes of the ternary system were correlated by the equation from Weiland et al. at each temperature. The parameters were in turn fitted by a polynomial function of the temperature.

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INTRODUCTION One of the methods for removing CO2 from the flue gas streams is the use of absorption and aqueous alkanolamine solutions as absorbents. Alkanolamines such as diethanolamine (DEA) and N-methyldiethanolamine (MDEA) are widely used in CO2 capture because of their high CO2 absorbing capacity and lower energy consumption. Physical properties such as the density of the pure compounds of amines, the mixtures with water, and CO2 loaded aqueous amine solutions are important for designing absorption−desorption processes. Maham et al.1 measured densities of unloaded aqueous DEA solutions at temperatures from (298.15 to 353.15) K and mole fractions of DEA from 0 to 1. Their tabulated value of pure DEA density at 298.15 K had been estimated by extrapolation of the densities of pure liquid DEA at high temperatures. Muhammad et al.2 measured the densities of unloaded aqueous MDEA solutions at temperatures from (298.15 to 338.15) K and mole fractions of MDEA from 0 to 1. Pouryousefi and Idem3 presented densities of unloaded aqueous MDEA solutions at temperatures from (296.15 to 333.15) K and mole fractions of MDEA from 0 to 1. Weiland et al.4 measured densities of CO2 loaded DEA solutions for mass fractions of DEA from 0.1 to 0.4 and CO2 loading from 0 to 0.5 at 298.15 K and also densities of CO2 loaded MDEA solutions for mass fractions of MDEA from 0.3 to 0.6 and CO2 loading from 0 to 0.5 at 298.15 K. Density data of unloaded and loaded aqueous DEA and MDEA solutions at higher temperatures are required for designing the CO2 desorption process and associated engineering calculations. In this work, densities of unloaded aqueous DEA solutions and unloaded aqueous MDEA solutions are measured at temperatures from (298.15 to 423.15) K and mass fractions of © 2012 American Chemical Society

Table 1. Chemical Sample Descriptions chemical name DEAa MDEAb carbon dioxide

source

initial mole fraction purity

Sigma Aldrich Sigma Aldrich AGA

purification method

analysis method

0.98

none

GCc

0.98

none

GCc

0.9999

none

a

Diethanolamine. bN-Methyldiethanolamine. cGas−liquid chromatography.

DEA or MDEA in water from 0.3 to 1.0. Densities of CO2 loaded aqueous DEA solutions and CO2 loaded aqueous MDEA solutions are measured at temperatures from (298.15 to 423.15) K, mass fractions of DEA or MDEA in water equal to 0.3 and 0.4, and CO2 loadings from 0.1 to 0.5.

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EXPERIMENTAL SECTION Aqueous solutions of DEA and MDEA were prepared with Milli-Q water (18.2 MΩ·cm). Amines and water were degassed by a rotary evaporator before mixing. The CO2 loaded aqueous solutions of DEA and MDEA were prepared by bubbling CO2 through an unloaded solution. The amount of CO2 loading was determined by a method based on precipitation of BaCO3 and titration. Unloaded and high CO2 loaded aqueous solutions of DEA and MDEA were then mixed to produce a set of samples with a range of CO2-loadings. Descriptions of DEA, MDEA, Received: March 18, 2012 Accepted: April 27, 2012 Published: May 9, 2012 1843

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x2

0 0.0684 0.1025 0.1463 0.2045 0.2856 0.4067 0.6066 1

0 0.0684 0.1025 0.1463 0.2045 0.2856 0.4067 0.6066 1

0 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

w2

0 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

w2

0 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

ρ

958.6 990.2 1000.9 1011.5 1021.2 1029.9 1037.2 1041.8 1043.3

983.2 1016.6 1028.3 1039.2 1049.9 1058.8 1065.6 1069.6 1070.8

ρ

106 VE

0 −0.222 −0.340 −0.457 −0.590 −0.680 −0.693 −0.541 0 K

10 V

E

106 VE 0 −0.187 −0.275 −0.375 −0.468 −0.555 −0.601 −0.498 0

0 −0.202 −0.304 −0.405 −0.525 −0.615 −0.644 −0.518 0 373.15 K

997.0 1034.0 1047.2 1059.5 1071.4 1081.0 1088.0 1092.2 1093.6 333.15

ρ

6

980.5 1013.8 1025.2 1036.0 1046.5 1055.3 1062.2 1066.3 1067.4

ρ

6

E

106 VE

977.7 1010.6 1022.0 1032.6 1043.1 1051.8 1058.8 1062.9 1064.0

ρ

6

E

943.4 974.2 984.7 995.1 1004.7 1013.5 1020.9 1026.0 1028.1

ρ

0 −0.200 −0.298 −0.396 −0.514 −0.599 −0.635 −0.513 0 393.15

106 VE

0 −0.216 −0.329 −0.441 −0.568 −0.659 −0.679 −0.530 0 K

10 V

308.15 K 994.0 1029.7 1042.4 1054.2 1065.6 1074.9 1081.8 1085.8 1087.1 343.15

ρ

0 −0.181 −0.266 −0.363 −0.454 −0.539 −0.584 −0.489 0

0 −0.205 −0.303 −0.401 −0.519 −0.607 −0.642 −0.516 0 383.15 K

106 VE

0 −0.216 −0.332 −0.447 −0.578 −0.668 −0.687 −0.531 0 K

10 V

951.2 982.3 992.9 1003.3 1012.9 1021.7 1028.9 1033.8 1035.5

ρ

995.6 1031.8 1044.8 1056.9 1068.5 1077.9 1085.0 1088.9 1090.4 338.15

ρ

303.15 K

0 −0.176 −0.259 −0.352 −0.440 −0.523 −0.570 −0.482 0

106 VE

974.8 1007.5 1018.8 1029.3 1039.7 1048.3 1055.3 1059.4 1060.6 K

ρ

992.2 1027.2 1039.6 1051.3 1062.6 1071.7 1078.7 1082.7 1083.8 348.15

ρ 6

E

935.1 965.8 976.3 986.7 996.2 1005.1 1012.8 1018.2 1020.5

ρ

0 −0.199 −0.298 −0.393 −0.509 −0.594 −0.631 −0.512 0

106 VE

0 −0.211 −0.320 −0.432 −0.559 −0.650 −0.674 −0.532 0 K

10 V

313.15 K

0 −0.172 −0.252 −0.343 −0.428 −0.509 −0.557 −0.475 0

106 VE

971.8 1004.2 1015.3 1025.8 1036.0 1044.8 1051.7 1055.9 1057.2 403.15 K

ρ

990.2 1024.9 1037.0 1048.4 1059.5 1068.6 1075.5 1079.5 1080.6 353.15

ρ 6

E

0 −0.197 −0.293 −0.387 −0.500 −0.589 −0.625 −0.509 0

106 VE

0 −0.211 −0.318 −0.426 −0.551 −0.640 −0.668 −0.530 0 K

10 V

318.15 K

926.3 957.1 967.5 977.9 987.5 996.5 1004.5 1010.2 1012.9

ρ

6

E

106 VE

0 −0.196 −0.291 −0.385 −0.496 −0.581 −0.619 −0.509 0

106 VE

0 −0.206 −0.312 −0.417 −0.547 −0.630 −0.658 −0.524 0 K

10 V

0 −0.169 −0.245 −0.334 −0.413 −0.492 −0.544 −0.467 0

968.6 1000.8 1011.9 1022.3 1032.5 1041.1 1048.0 1052.4 1053.7 413.15 K

ρ

988.0 1022.2 1034.2 1045.4 1056.6 1065.3 1072.2 1076.2 1077.4 358.15

ρ

323.15 K

917.1 947.9 958.1 969.0 978.2 987.2 995.4 1001.7 1004.8

ρ

106 VE

0 −0.195 −0.288 −0.379 −0.489 −0.569 −0.616 −0.504 0

106 VE

0 −0.207 −0.311 −0.412 −0.534 −0.622 −0.653 −0.523 0 K

106 VE

0 −0.163 −0.232 −0.332 −0.395 −0.465 −0.515 −0.454 0

965.3 997.3 1008.3 1018.6 1028.7 1037.2 1044.4 1048.8 1050.1 423.15 K

ρ

985.7 1019.5 1031.4 1042.4 1053.2 1062.1 1068.9 1073.0 1074.1 363.15

ρ

328.15 K

The data were measured under 0.1 MPa from (298.15 to 363.15) K and under 0.7 MPa from (373.15 to 423.15) K. bPure water data are from IAPWS.5 Excess molar volumes of aqueous DEA solutions here are derived data. cStandard uncertainties u are u(T) = 0.03 K at T < 373.15 K and u(T) = 0.05 K at T ≥ 373.15 K, u(w2) = 0.02, and the combined expanded uncertainty is Uc(ρ) = 3.51 kg·m−3 (level of confidence = 0.95).

a

0 0.0684 0.1025 0.1463 0.2045 0.2856 0.4067 0.6066 1

x2

x2

w2

298.15 K

Table 2. Mass Fraction w, Liquid Densities ρ/kg·m−3, and Deduced Excess Molar Volume VmE/m3·mol−1 for [Water (1) + DEA (2)] Mixturea,b,c

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and CO2 are given in Table 1. All samples were prepared using an analytical balance with an accuracy of ± 1·10−7 kg. A combination of Anton Paar density meters DMA 4500 and DMA HP were used for the density measurements. The measuring temperature range of DMA 4500 is from (273.15 to 363.15) K, and it only works at normal atmosphere, while the measuring temperature range of DMA HP is from (263.15 to 473.15) K, and it can work at the pressures from (0 to 70) MPa. Each sample is injected into a measurement cell by a syringe. Instrument accuracy for DMA 4500 is given as ± 0.05 kg·m−3 by the manufacturer, while for DMA HP the accuracy is given as ± 0.1 kg·m−3.

■

RESULTS AND DISCUSSION All of the density measurements and the deduced excess molar volumes of water (1) + DEA (2) solutions at temperatures from (298.15 to 423.15) K and mass fractions of DEA from 0 to 1 are given in Table 2. Figure 1 displays the densities of

Figure 2. Comparison of measured and literature densities of H2O (1) + DEA (2) solutions for three mass fractions of DEA. This work: ◊, 0.3; □, 0.6; △, 1.0; and values from Maham et al.:1 ×, 0.3; ∗, 0.6; , 1.0. Lines are calculated by the Redlich−Kister equation.

Figure 3. Densities of the H2O (1) + MDEA (2) solutions as a function of mass fraction of MDEA at selected temperatures. Symbols refer to the experimental data: ◊, 298.15 K; □, 333.15 K; △, 363.15 K; ×, 383.15 K; ∗, 403.15 K; ○, 423.15 K. Lines are calculated by the Redlich−Kister equation.

Figure 1. Densities of the H2O (1) + DEA (2) solutions as a function of mass fraction of DEA at selected temperatures. Symbols refer to the experimental data: ◊, 298.15 K; □, 333.15 K; △, 363.15 K; ×, 383.15 K; ∗, 403.15 K; ○, 423.15 K. Lines are calculated by the Redlich−Kister equation.

unloaded aqueous DEA solutions as a function of concentration for selected temperatures. It can be seen from Figure 1 that densities of unloaded aqueous DEA solutions decrease with the temperature increasing and increase with the DEA concentration becoming greater. The comparison to the data from the literature is shown in Figure 2. The agreement between the measured densities of unloaded aqueous DEA solutions and the results from Maham et al.1 is good. The maximum deviation between them is 1.7 kg·m−3, which is within the experimental uncertainty. All of the densities and the deduced excess molar volumes of water (1) + MDEA (2) solutions at temperatures from (298.15 to 423.15) K and mass fractions of MDEA from 0 to 1 are given in Table 3. Figure 3 indicates the trend of densities of unloaded aqueous MDEA solutions as a function of concentration at various temperatures. Densities of unloaded aqueous MDEA solutions increase at first and then decrease when the MDEA concentration increases. The maximum value occurs at w2 = 0.7 for the whole temperature range. Pure MDEA densities are higher than that of water. Figure 4 shows the comparison of measured densities of unloaded aqueous MDEA solutions to the data from the literature. The maximum deviation is 2.4 kg·m−3 when compared to the data from Muhammad et al.2

Figure 4. Comparison of measured and literature densities of H2O (1) + MDEA (2) solutions for three mass fractions of MDEA. This work: ◊, 0.3; □, 0.7; values from Muhammad et al.:2 △, 0.3; and values from Pouryousefi and Idem:3 ×, 0.3; ∗, 0.7. Lines are calculated by the Redlich−Kister equation.

and 1.2 kg·m−3 when compared to the data from Pouryousefi and Idem.3 The deviations between them are within the experimental uncertainty. It can also be seen from Figure 4 that densities of unloaded aqueous MDEA solutions decrease with the temperature rising. 1845

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ρ

958.6 977.2 982.9 987.6 990.7 992.0 990.6 985.7 978.6

983.2 1005.9 1013.8 1020.1 1023.6 1026.6 1025.0 1019.0 1009.4

ρ

997.0 1025.2 1035.6 1043.3 1049.7 1053.6 1052.3 1046.0 1036.0 333.15

ρ E

ρ

980.5 1002.7 1010.3 1016.3 1019.8 1022.5 1020.9 1015.0 1005.6

ρ

E

977.7 999.3 1006.7 1012.5 1015.9 1018.4 1016.8 1010.9 1001.7

ρ

0 −0.312 −0.449 −0.593 −0.732 −0.849 −0.887 −0.687 0

6

E

943.4 960.2 965.2 969.3 972.1 973.3 972.2 968.1 962.1

ρ

0 −0.356 −0.536 −0.714 −0.873 −1.051 −1.107 −0.881 0 393.15

106 VE

0 −0.216 −0.329 −0.441 −0.568 −0.659 −0.679 −0.530 0 K

10 V

308.15 K 994.0 1020.3 1029.9 1037.6 1042.5 1046.2 1044.8 1038.4 1028.6 343.15

ρ

106 VE

0 −0.359 −0.543 −0.725 −0.883 −1.070 −1.122 −0.894 0 383.15 K

106 VE

0 −0.216 −0.332 −0.447 −0.578 −0.668 −0.687 −0.531 0 K

951.2 968.8 974.1 978.5 981.4 982.6 981.4 976.9 970.3

ρ

6

10 V

303.15 K 995.6 1022.8 1032.8 1040.9 1046.1 1049.9 1048.6 1042.3 1032.4 338.15

0 −0.325 −0.470 −0.623 −0.772 −0.895 −0.936 −0.720 0

106 VE

0 −0.364 −0.550 −0.738 −0.893 −1.089 −1.144 −0.911 0 373.15 K

106 VE

0 −0.222 −0.340 −0.457 −0.590 −0.680 −0.693 −0.541 0 K

10 V

6

0 −0.298 −0.427 −0.564 −0.693 −0.803 −0.837 −0.649 0

106 VE

974.8 995.9 1003.0 1008.5 1011.9 1014.2 1012.6 1006.9 997.7 K

ρ

992.2 1017.7 1026.9 1034.3 1038.8 1042.4 1040.9 1034.6 1024.8 348.15

ρ 6

E

935.1 951.2 955.9 959.8 962.5 963.7 962.9 959.3 953.9

ρ

0 −0.353 −0.529 −0.705 −0.860 −1.036 −1.092 −0.875 0

106 VE

0 −0.211 −0.320 −0.432 −0.559 −0.650 −0.674 −0.532 0 K

10 V

313.15 K

0 −0.285 −0.406 −0.533 −0.654 −0.756 −0.785 −0.613 0

106 VE

971.8 992.3 999.2 1004.6 1007.7 1009.9 1008.4 1002.7 993.8 403.15 K

ρ

990.2 1014.9 1023.8 1030.8 1034.7 1038.5 1037.0 1030.8 1021.0 353.15

ρ 6

E

0 −0.349 −0.521 −0.694 −0.845 −1.017 −1.071 −0.859 0

106 VE

0 −0.211 −0.318 −0.426 −0.551 −0.640 −0.668 −0.530 0 K

10 V

318.15 K

926.3 941.9 946.4 950.1 952.7 954.0 953.4 950.4 945.6

ρ

6

E

0 −0.345 −0.513 −0.680 −0.828 −0.978 −1.051 −0.842 0

106 VE

0 −0.370 −0.563 −0.758 −0.914 −1.121 −1.174 −0.927 0 K

10 V

0 −0.271 −0.384 −0.501 −0.612 −0.707 −0.733 −0.572 0

106 VE

968.6 988.7 995.3 1000.4 1003.5 1005.2 1004.1 998.6 989.9 413.15 K

ρ

988.0 1012.0 1020.6 1027.3 1031.1 1034.6 1033.1 1026.9 1017.2 358.15

ρ

323.15 K

917.1 931.9 936.1 939.6 942.3 943.6 943.4 940.9 937.0

ρ

0 −0.341 −0.505 −0.669 −0.813 −0.961 −1.032 −0.830 0

106 VE

0 −0.367 −0.557 −0.748 −0.898 −1.105 −1.159 −0.920 0 K

106 VE

0 −0.249 −0.351 −0.453 −0.558 −0.641 −0.669 −0.516 0

106 VE

965.3 984.9 991.3 996.3 999.2 1000.9 999.8 994.4 985.9 423.15 K

ρ

985.7 1009.0 1017.2 1023.7 1027.3 1030.6 1029.1 1022.9 1013.3 363.15

ρ

328.15 K

a The data were measured under 0.1 MPa from (298.15 to 363.15) K and under 0.7 MPa from (373.15 to 423.15) K. bPure water data are from IAPWS.5 Excess molar volumes of aqueous MDEA solutions here are derived data. cStandard uncertainties u are u(T) = 0.03 K at T < 373.15 K and u(T) = 0.05 K at T ≥ 373.15 K, u(w2) = 0.02, and the combined expanded uncertainty is Uc(ρ) = 3.01 kg·m−3 (level of confidence = 0.95).

0 0.0609 0.0916 0.1313 0.1848 0.2608 0.3768 0.5764 1

0 0.0609 0.0916 0.1313 0.1848 0.2608 0.3768 0.5764 1

0 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

x2

w2

x2

0 0.0609 0.0916 0.1313 0.1848 0.2608 0.3768 0.5764 1

0 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

w2

x2

w2

298.15 K

Table 3. Mass Fraction w, Liquid Densities ρ/kg·m−3, and Deduced Excess Molar Volume VmE/m3·mol−1 for [Water (1) + MDEA (2)] Mixturea,b,c

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Table 4. Liquid Densities ρ for Water (1) + DEA (2) + CO2 (3) from T = (298.15 to 423.15) K and CO2 Loading from α = nCO2/nDEA = (0.1 to 0.5) at w2 = 0.3a α 0.1 T

p

0.2 ρ

p −3

K

MPa

kg·m

298.15 303.15 313.15 323.15 333.15 343.15 353.15 363.15 373.15 383.15 393.15 403.15 413.15 423.15

0.101 0.101 0.101 0.101 0.101 0.101 0.101 0.101 0.808 0.808 0.808 0.808 0.808 0.808

1046.2 1044.1 1039.4 1034.2 1028.7 1022.6 1016.2 1009.4 1002.4 994.8 986.8 978.4 969.6 958.4

0.3 ρ

p −3

MPa

kg·m

0.101 0.101 0.101 0.101 0.101 0.101 0.101 0.808 0.808 0.808 0.808 0.808 0.808

1058.9 1056.6 1051.8 1046.6 1041.0 1034.9 1028.5 1022.0 1014.9 1007.3 999.1 990.7 981.5

0.4 ρ

p −3

0.5 ρ −3

MPa

kg·m

MPa

kg·m

0.101 0.101 0.101 0.101 0.101 0.101 0.101 0.808 0.808 0.808 0.808 0.808

1071.8 1069.0 1063.8 1058.5 1052.8 1046.7 1040.2 1033.9 1026.6 1019.0 1011.3 1002.2

0.101 0.101 0.101 0.101 0.101 0.101 0.101 0.808 0.808 0.808 0.808

1083.4 1080.6 1075.4 1070.0 1064.2 1058.0 1051.5 1045.0 1037.6 1030.0 1021.6

p

ρ

MPa

kg·m−3

0.101 0.101 0.101 0.101 0.101 0.101 0.808 0.808 0.808 0.808

1093.1 1090.7 1085.5 1080.0 1074.1 1067.9 1061.1 1054.6 1047.2 1038.9

a w2 is the mass fraction of DEA in the (water + DEA) solutions. Standard uncertainties u are u(T) = 0.03 K at T < 373.15 K and u(T) = 0.05 K at T ≥ 373.15 K, u(w2) = 0.02, u(α) = 0.003, and the combined expanded uncertainty is Uc(ρ) = 12 kg·m−3 (level of confidence = 0.95).

Figure 5. Densities of the H2O (1) + DEA (2) + CO2 (3) solutions as a function of temperature at different mass fractions of DEA and CO2 loadings. Symbols refer to the experimental data: ◊, w2 = 0.3, α = 0.1; □, w2 = 0.3, α = 0.3; △, w2 = 0.3, α = 0.5; ×, w2 = 0.4, α = 0.1; ○, w2 = 0.4, α = 0.5. Lines are the correlated results from eqs 5 and 6.

Figure 7. Densities of the H2O (1) + MDEA (2) + CO2 (3) solutions as a function of temperature at different mass fractions of MDEA and CO2 loadings. Symbols refer to the experimental data: ◊, w2 = 0.3, α = 0.1; □, w2 = 0.3, α = 0.3; △, w2 = 0.3, α = 0.5; ×, w2 = 0.4, α = 0.1; ○, w2 = 0.4, α = 0.5. Lines are the correlated results from eqs 5 and 6.

Figure 6. Comparison of measured and literature densities of H2O (1) + DEA (2) + CO2 (3) solutions as a function of CO2 loading at 298.15 K. This work: ◊, w2 = 0.3; □, w2 = 0.4; and values from Weiland et al.:4 ×, w2 = 0.3; , w2 = 0.4.

Figure 8. Comparison of measured and literature densities of H2O (1) + MDEA (2) + CO2 (3) solutions as a function of CO2 loading at 298.15 K. This work: ◊, w2 = 0.3; □, w2 = 0.4; and values from Weiland et al.:4 ×, w2 = 0.3; , w2 = 0.4. 1847

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Table 5. Liquid Densities ρ for Water (1) + DEA (2) + CO2 (3) from T = (298.15 to 423.15) K and CO2 Loading from α = nCO2/nDEA = (0.1 to 0.5) at w2 = 0.4a α 0.1 T

0.2 ρ

p

−3

K

MPa

kg·m

298.15 303.15 313.15 323.15 333.15 343.15 353.15 363.15 373.15 383.15 393.15 403.15 413.15 423.15

0.101 0.101 0.101 0.101 0.101 0.101 0.101 0.101 0.808 0.808 0.808 0.808 0.808 0.808

1062.8 1060.3 1055.1 1049.6 1043.7 1037.5 1030.9 1023.9 1016.7 1009.0 1000.9 992.5 984.1 973.4

0.3 ρ

p

−3

MPa

kg·m

0.101 0.101 0.101 0.101 0.101 0.101 0.101 0.808 0.808 0.808 0.808 0.808 0.808

1079.6 1076.8 1071.2 1065.6 1059.8 1053.5 1047.0 1040.1 1033.1 1025.6 1017.4 1008.9 1000.5

0.4 ρ

p

−3

0.5 ρ

p

−3

MPa

kg·m

MPa

kg·m

0.101 0.101 0.101 0.101 0.101 0.101 0.101 0.808 0.808 0.808 0.808 0.808

1094.6 1091.6 1086.0 1080.4 1074.5 1068.2 1061.6 1054.7 1047.9 1040.3 1032.1 1023.4

0.101 0.101 0.101 0.101 0.101 0.101 0.101 0.808 0.808 0.808 0.808

1109.0 1106.4 1101.0 1095.3 1089.3 1082.9 1076.3 1069.9 1062.4 1054.8 1046.4

p

ρ

MPa

kg·m−3

0.101 0.101 0.101 0.101 0.101 0.101 0.808 0.808 0.808 0.808

1123.0 1120.3 1114.8 1108.9 1102.9 1096.4 1090.3 1083.1 1075.7 1067.7

a w2 is the mass fraction of DEA in the (water + DEA) solutions. Standard uncertainties u are u(T) = 0.03 K at T < 373.15 K and u(T) = 0.05 K at T ≥ 373.15 K, u(w2) = 0.02, u(α) = 0.003, and the combined expanded uncertainty is Uc(ρ) = 12 kg·m−3 (level of confidence = 0.95).

Table 6. Liquid Densities ρ for Water (1) + MDEA (2) + CO2 (3) from T = (298.15 to 423.15) K and CO2 Loading from α = nCO2/nMDEA = (0.1 to 0.5) at w2 = 0.3a α 0.1

0.2

0.3

0.4

0.5

T

p

ρ

p

ρ

p

ρ

p

ρ

p

ρ

K

MPa

kg·m−3

MPa

kg·m−3

MPa

kg·m−3

MPa

kg·m−3

MPa

kg·m−3

298.15 303.15 313.15 323.15 333.15 343.15 353.15 363.15 373.15 383.15 393.15 403.15 413.15 423.15

0.101 0.101 0.101 0.101 0.101 0.101 0.101 0.808 0.808 0.808 0.808 0.808 0.808 0.808

1036.1 1033.6 1028.3 1022.5 1016.3 1009.7 1002.7 995.6 988.1 979.9 970.9 961.8 951.9 944.1

0.101 0.101 0.101 0.101 0.101 0.101 0.101 0.808 0.808 0.808 0.808 0.808 0.808

1046.6 1044.1 1038.6 1032.7 1026.5 1019.9 1012.9 1005.8 998.1 990.2 981.5 971.3 959.9

0.101 0.101 0.101 0.101 0.101 0.101 0.101 0.808 0.808 0.808 0.808

1056.5 1053.9 1048.3 1042.4 1036.1 1029.5 1022.5 1015.0 1007.2 998.8 987.3

0.101 0.101 0.101 0.101 0.101 0.101 0.808 0.808 0.808 0.808

1064.5 1061.9 1056.2 1050.3 1044.1 1037.5 1030.8 1023.4 1015.6 1007.5

0.101 0.101 0.101 0.101 0.101 0.101 0.808 0.808 0.808

1074.7 1072.0 1066.3 1060.4 1054.2 1047.6 1040.9 1033.0 1025.2

a w2 is the mass fraction of MDEA in the (water + MDEA) solutions. Standard uncertainties u are u(T) = 0.03 K at T < 373.15 K and u(T) = 0.05 K at T ≥ 373.15 K, u(w2) = 0.02, u(α) = 0.003, and the combined expanded uncertainty is Uc(ρ) = 11.2 kg·m−3 (level of confidence = 0.95).

of CO2 loaded MDEA solutions as a function of temperature at different compositions. The trend is the same as for CO2 loaded aqueous DEA solutions. The measured densities of CO2 loaded aqueous MDEA solutions are very close to the data from Weiland et al.4 as evidenced shown in Figure 8. The maximum deviation between this work and the literature data is 3.3 kg·m−3, which is within the experimental uncertainty. Some densities of CO2 loaded aqueous amine solutions at high temperatures could not be measured because bubbles formed inside the external measuring cell. The pressure needed to prevent CO2 desorption is obviously higher than that in our gas supply system which was limited to 0.808 MPa.

Density measurements of water (1) + DEA (2) + CO2 (3) solutions are given in Tables 4 and 5. Figure 5 shows densities of CO2 loaded aqueous DEA solutions as a function of temperature at mass fraction of DEA w2 = 0.3 and 0.4 and different CO2 loadings. Densities of CO2 loaded aqueous DEA solutions decrease with the temperature rising but increase with increased CO2 loading. Figure 6 illustrates the comparison of the measured densities of CO2 loaded aqueous DEA solutions to the data from Weiland et al.4 at 298.15 K. The agreement is good. The maximum deviation between them is 4.0 kg·m−3. Density measurements of water (1) + MDEA (2) + CO2 (3) solutions are given in Tables 6 and 7. Figure 7 displays densities 1848

dx.doi.org/10.1021/je300345m | J. Chem. Eng. Data 2012, 57, 1843−1850

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Table 7. Liquid Densities ρ for Water (1) + MDEA (2) + CO2 (3) from T = (298.15 to 423.15) K and CO2 Loading from α = nCO2/nMDEA = (0.1 to 0.5) at w2 = 0.4a α 0.1 T

0.2 ρ

p

−3

K

MPa

kg·m

298.15 303.15 313.15 323.15 333.15 343.15 353.15 363.15 373.15 383.15 393.15 403.15 413.15 423.15

0.101 0.101 0.101 0.101 0.101 0.101 0.101 0.808 0.808 0.808 0.808 0.808 0.808

1049.4 1046.5 1040.5 1034.1 1027.4 1020.4 1012.9 1005.2 997.3 988.8 979.7 970.4 960.1

0.3 ρ

p

0.4 ρ

p −3

MPa

kg·m

0.101 0.101 0.101 0.101 0.101 0.101 0.101 0.808 0.808 0.808 0.808

1063.3 1060.4 1054.2 1047.8 1041.1 1034.1 1026.7 1019.4 1011.1 1002.5 993.3

p −3

0.5 ρ −3

MPa

kg·m

MPa

kg·m

0.101 0.101 0.101 0.101 0.101 0.101 0.808 0.808 0.808 0.808

1076.9 1073.9 1067.7 1061.3 1054.6 1047.5 1040.5 1032.5 1024.6 1015.7

0.101 0.101 0.101 0.101 0.101 0.808 0.808 0.808 0.808

1089.8 1086.8 1080.6 1074.1 1067.4 1060.8 1053.5 1045.7 1037.5

p

ρ

MPa

kg·m−3

0.101 0.101 0.101 0.101 0.101 0.808 0.808 0.808

1102.6 1099.5 1093.3 1086.9 1080.2 1072.9 1066.3 1057.8

a w2 is the mass fraction of MDEA in the (water + MDEA) solutions. Standard uncertainties u are u(T) = 0.03 K at T < 373.15 K and u(T) = 0.05 K at T ≥ 373.15 K, u(w2) = 0.02, u(α) = 0.003, and the combined expanded uncertainty is Uc(ρ) = 11.2 kg·m−3 (level of confidence = 0.95).

Table 8. Coefficients for Liquid Density Correlations of Unloaded Aqueous DEA Solutions and Unloaded Aqueous MDEA Solutions Redlich−Kister parameter

R-K temperature coefficient

DEA

MDEA

A0

a00 a01 a02 a10 a11 a12 a20 a21 a22 a30 a31 a32 a40 a41 a42

−2.67 0.0032 0.000002 −1.42 0.002 0.00004 0.16 −0.0062 0.0001 −6.6 0.11 −0.0008 7.97 −0.12 0.0007

−4.95 0.0029 0.0001 −3.36 0.0096 0.000006 7.32 0.068 −0.0008 −24.65 −0.089 0.0017 20.09 0.0009 −0.0009

A1

A2

A3

A4

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Table 9. Parameters for Liquid Density Correlations of CO2 Loaded Aqueous DEA Solutions and CO2 Loaded Aqueous MDEA Solutions parameters B1

B2

B3

B4

MODEL FOR DATA REPRESENTATION The excess molar volumes have been calculated by eq 1 to analyze the densities of unloaded aqueous amine solutions. (1)

−99.03 1.56 −0.003 −0.00006 −4.5 0.039 −0.0006 0.000003 2569.2 −40.79 0.12 0.0012 −15362 251.53 −0.82 −0.0065

150.76 −6.62 0.064 0 −7.9 0.02 −0.00005 0 −4014.7 185.57 −1.79 0 26682 −1250.2 12.05 0

Aj = aj0 + aj1(T /K − 273.15) + aj2(T /K − 273.15)2

Here V E represents the excess molar volume of the mixture, and V is the molar volume of the mixture. Furthermore Vjo and xj are molar volume and mole fraction respectively for component j. j = 1 refers to water and 2 to amine. Superscript o refers to the pure component data. The excess molar volumes are correlated with the polynomial Redlich−Kister6 equation by least-squares fitting.

(3)

The fitted coefficients of the Redlich−Kister equations for excess molar volumes of unloaded aqueous DEA solutions and unloaded aqueous MDEA solutions are given in Table 8. The maximum deviation between the measured densities of unloaded aqueous DEA solutions and the correlation is 2.1 kg·m−3, and the average absolute deviation is 0.3 kg·m−3. The maximum deviation for unloaded aqueous MDEA solutions is 1.2 kg·m−3, and the average absolute deviation is 0.3 kg·m−3. These deviations are within the experimental error.

i j=0

MDEA

Here Aj are adjustable coefficients. i was chosen as 4 for the measured data. The parameters of the Redlich−Kister equation are in turn fitted to a second-order polynomial function of temperature as suggested by Mandal et al.7

V E/m 3·mol−1 = V /m 3·mol−1 − ((V1o/m 3·mol−1)x1 + (V 2o/m 3·mol−1)x 2)

V E/m 3·mol−1 = x 2(1 − x 2) ∑ Aj(1 − 2x 2) j ·10−6

b10 b11 b12 b13 b20 b21 b22 b23 b30 b31 b32 b33 b40 b41 b42 b43

DEA

(2) 1849

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Journal of Chemical & Engineering Data

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Molar volumes have been calculated by eq 4 to analyze densities of CO2 loaded aqueous amine solutions. V /m 3·mol−1 x (M /kg·mol−1) + x 2(M 2 /kg·mol−1) + x3(M3/kg·mol−1) = 1 1 ρ /kg·m−3

(4)

V /m 3·mol−1 = x1(V1o/m 3·mol−1) + x 2(V 2o/m 3·mol−1)

(5)

n

Bi =

∑ bik(T /K − 273.15)k k=0

REFERENCES

(1) Maham, Y.; Teng, T. T.; Hepler, L. G.; Mather, A. E. Densities, Excess Molar Volumes, and Partial Molar Volumes for Binary Mixtures of Water with Monoethanolamine, Diethanolamine, and Triethanolamine from 25 °C to 80 °C. J. Solution Chem. 1994, 23, 195−205. (2) Muhammad, A.; Mutalib, M. A.; Murugesan, T.; Shafeeq, A. Density and Excess Properties of Aqueous N-Methyldiethanolamine Solutions from (298.15 to 338.15) K. J. Chem. Eng. Data 2008, 53, 2217−2221. (3) Pouryosefi, F.; Idem, R. O. New Analytical Technique for Carbon Dioxide Absorption Solvents. Ind. Eng. Chem. Res. 2008, 47, 1268− 1276. (4) Weiland, R. H.; Dingman, J. C.; Cronin, D. B.; Browning, G. J. Density and Viscosity of Some Partially Carbonated Aqueous Alkanolamine Solutions and Their Blends. J. Chem. Eng. Data 1998, 43, 378−382. (5) Harvey, A. H. Thermodynamic Properties of Water; NIST: Boulder, CO, 1998. (6) Redlich, O.; Kister, A. T. Algebraic representation of thermodynamic properties and the classification of solutions. Ind. Eng. Chem. 1948, 40, 345−348. (7) Mandal, B. P.; Kundu, M.; Bandyopadhyay, S. S. Density and Viscosity of Aqueous Solutions of (N-Methyldiethanolamine + Monoethanolamine), (N-Methyldiethanolamine + Diethanolamine), (2-Amino-2-methyl-1-propanol + Monoethanolamine), (2-Amino-2methyl-1-propanol + Diethanolamine). J. Chem. Eng. Data 2003, 48, 703−707.

The molar volumes of CO2 loaded aqueous amine solutions are correlated by eq 5 as suggested by Weiland et al.4 The parameters Bi are in turn fitted to the polynomial function of temperature as shown in eq 6. + (x3B1 + x1x 2B2 + x 2x3(B3 + B4 x 2))·10−6

Article

(6)

Vjo,

Here xj, and Mj are molar volume, mole fraction, and molar mass, respectively, for component j. No subscript refers to the mixture, j = 1 refers to water, 2 to amine, and 3 to CO2. Superscript o refers to the pure component data. The mole fractions x1, x2, and x3 have been calculated from the mass fraction of amine and CO2 loading. A third-order polynomial relationship to temperature (n = 3) was used for CO2 loaded aqueous DEA solutions, while a second-order polynomial equation (n = 2) was used for CO2 loaded aqueous MDEA solutions. The polynomial fitting equation with higher order will produce more errors. The values of the fitted coefficients are presented in Table 9. The maximum deviation between the measured densities of CO2 loaded aqueous DEA solutions and the correlated data is 5.4 kg·m−3, and the average absolute deviation is 1.3 kg·m−3. The maximum deviation for CO2 loaded aqueous MDEA solutions is 2.5 kg·m−3, and the average absolute deviation is 0.8 kg·m−3. These deviations are within the experimental error.

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CONCLUSIONS In this study, density data for the systems water + DEA and water + MDEA at amine mass fractions from 0.3 to 1.0 at temperatures from (298.15 to 423.15) K have been measured. Excess molar volumes of the binary system were correlated by the Redlich−Kister equation. Density data for the systems water + DEA + CO2 and water + MDEA + CO2 at different amine mass fractions (0.3, 0.4) and different CO2 loadings (0.1, 0.2, 0.3, 0.4, 0.5) at temperatures from (298.15 to 423.15) K have also been measured. Molar volumes of the ternary system were fitted by the equation from Weiland et al.4 The deviations between the measured results and the correlated data by the regressed models are less than the experimental error.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Telephone number: +47 35575286. Fax number: +47 35575001. Funding

The authors would like to thank the Norwegian Research Council and Statoil for financial support. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS The assistance of Mengning Xu and Sigbjørn Wiersdalen are gratefully acknowledged. 1850

dx.doi.org/10.1021/je300345m | J. Chem. Eng. Data 2012, 57, 1843−1850