Aqueous Mixtures of Monoethanolamine

with 2-Amino-2-Ethyl-1,3-Propanediol에 대한 물성 측정

박정연 , 이현송, 윤상준, 이흔

한국과학기술원 화학공학과

Physical Properties of Aqueous Mixtures of Monoethanolamine

with 2-Amino-2-Ethyl-1,3-Propanediol

Jung-yeon Park, Hyun-song Lee, Sang-jun Yoon, and Huen Lee

Department of Chemical Engineering, KAIST

1. Introduction

Aqueous solutions of alkanolamines are used in the petroleum industry to remove acid gases from natural gas in refining and purification processes. Monoethanolamine has been widely used in carbon dioxide and hydrogen sulfide removal processes because of its low cost, high reactivity to the acid gases, and fast reaction with CO2. Monoethanolamine, however, has a sharp corrosion effect. Recently, sterically hindered amines have been studied and proved that they have higher CO2 absorption capacity and easier regeneration due to low heat of reaction than conventional amines, but rate of reaction with CO2 is quite slow. Mixed solution of MEA and AEPD, sterically hindered amine, is expected to show compensation for their advantages and disadvantages. The physical property of aqueous solution is required for the design of acid gas treatment equipments. In this work, density, viscosity, and surface tension of aqueous mixtures of monoethanolamine with 2-amino-2-ethyl-1,3-propanediol are measured at various temperatures and concentrations.

2. Experimental Section

Materials. Monoethanolamine(99%) from Aldrich Chemical Co. and 2-amino-2-ethyl-1,3-propanediol(97%) from Acros Organics were obtained and used without further purification. Aqueous mixtures of MEA with AEPD were prepared using triple-distilled water.

Apparatus and procedure. Densities were measured by using calibrated pycnometers. A water bath was used to maintain a constant temperature of pycnomerers containing liquid solutions. The temperatures of the water bath could be kept constant within ±0.05K by an externally circulating refrigerator/heater. Temperature was measured by calibrated mercury-filled glass thermometer. A Satorius R120S balance with a precision of ±0.0001g was used for weight measurements of liquid mixtures.

Viscosities were measured by using well-calibrated Ubbelohde-type viscometers(Witeg) of various capillary sizes. An appropriate viscometer was clamped in the constant temperature water bath controlled within ±0.05K. An electronic stopwatch with an accuracy of 0.01s was used to measure the efflux time of liquid solution. The accuracy of the measured viscosity was estimated to be within ±1%

Surface tension was measured by using cathetometer and capillary tube. The temperature could be kept constant within ±0.05K by water circulator. The temperature of the liquid sample was measured directly by the calibrated glass thermometer with a precision of ±0.1K. The height of liquid rise in the capillary tube was determined by the cathetometer (N.O.W.NCM 30) with an accuracy of 10-5m. The diameter of capillary tube was calibrated with benzene at various temperatures and averaged value of diameter was used to calculate surface tension. The detailed procedure for measuring surface tension was described elsewhere.

3.Results and Discussion

Densities, viscosities, and surface tensions of the aqueous MEA+AEPD solution were measured in the temperature range of 303.15 to 343.15K and in the concentration range of 5/25, 10/20, 15/15, 20/10, and 25/5wt%. Each data set was correlated with the appropriate  regression equation as a function of temperature and concentration.

The measured density values are represented in figure 1. As the temperature of mixtures and the concentration of MEA increase, the density values decrease linearly. The density values were regressed by the following equation.

where, □ is the density of the solution, T is the absolute temperature in K, Ai, Bi, and Ci are the regression coefficients, and x is the weight fraction of MEA.

The measured viscosity values are represented in figure 2. As the temperature of mixtures and the concentration of MEA increase, the viscosity values decrease. The viscosity values were regressed by the following equation.

where, □is the viscosity of the solution, T is the absolute temperature in K, Ai, Bi, and Ci are the regression coefficients, and x is the weight fraction of MEA.

The measured surface tension values are represented in figure 3. As the temperature of mixtures and the concentration of AEPD increase, the surface tension values decrease linearly. The surface tension values were regressed by the following equation.

.

where, □ is the surface tension of the solution, T is the absolute temperature in K, Ai, Bi, and Ci are the regression coefficients, and x is the weight fraction of MEA.

4. Conclusion

Densities, viscosities, and surface tensions of the aqueous MEA+AEPD solution were measured in the temperature range of 303.15 to 343.15K and in the concentration range of 5/25, 10/20, 15/15, 20/10, and 25/5wt%. All physical properties were correlated by appropriate equations and correlation parameters were obtained. Measured and calculated values were in good agreement within 0.006% for density, 1% for viscosity, and 0.1% for surface tension in AADs.

5. Reference

1. Satory, G.; Savage, D. W. Sterically Hindered Amines for CO2 Removal from Gases. Ind. Eng. Chem. Fundam. 1983, 22, 239-249.

2. Baek, J.-I.; Yoon, J.-H.; Eum, H.-M. Physical and Thermodynamic Properties of Aqueous 2-Amino-2-methyl-1,3-propanedion Solutions. Int. J. Thermophys. 2000, 21, 1175-1184.

3. Lee, J.-W.; Park, S.-B.; Lee, H. Density, Surface tension, and Refractive Indices of the Water + 1,3-Propanediol System. J. Chem. Eng. Data 2000,45,166-168.

Figure 1.   Density of Water + MEA + AEPD system

( wt% of AEPD / MEA:◇5/25 △10/20 ●15/15 ▲20/10 ◆25/5 )

Figure 2.   Viscosity of Water + MEA + AEPD system

( wt% of AEPD / MEA:◇5/25 △10/20 ●15/15 ▲20/10 ◆25/5 )

Figure 3.   Surface tension of Water + MEA + AEPD system

( wt% of AEPD / MEA:◇5/25 △10/20 ●15/15 ▲20/10 ◆25/5 )