AHPD수용액에 대한 이산화탄소의 용해도

박정연, 윤상준, 윤지호*, 엄희문*, 이흔

한국과학기술원 화학공학과

한국전력연구원*

Solubility of Carbon Dioxide in Aqueous Solutions of 2-Amino-2-hydroxymethyl-1,3-Propanediol(AHPD)

Jung-yeon Park, Sang-jun Yoon, Ji-ho Yoon*, Hee-moon Eum*, Huen Lee

Department of Chemical Engineering, KAIST

Korea Electric Power Research Institute*

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. In this study 2-Amino-2-hydroxymethyl-1,3-Propanediol(AHPD) aqueous solutions have been studied to ascertain if it is an effective CO2 absorbent. The solubility of  CO2 in AHPD aqueous solutions has not been reported in the literature. The equilibrium solubility of  CO2 in 10 and 20 wt% AHPD aqueous solutions was measured at 313.15, 323.15, and 333.15 K and over the  partial pressure range of 0.5∼2000 kPa.

Experimental Section

The equilibrium solubility of CO2 in alkanolamine aqueous solutions was measured by using an equilibrium cell made of 316 stainless steel. The equilibrium cell with an internal volume of about 450ml was mounted in a water bath kept at ±0.1 oC of the set point temperature by a refrigerator/heater(Jeio Tech, RBC-20). The temperature in the  equilibrium cell was measured by a K-type thermocouple with a digital thermometer of which the resolution is ±0.1 oC. The system pressure was measured by a bourdon tube type of pressure gauge (Heise. CMM-123928) with an accuracy of ±0.1% of the full-scale span [(0 to 5170)kPa]. The composition of the vapor phase was determined by a gas chromatograph (Hewlett-Packard, 5890 Series Ⅱ Plus). The gas chromatograph includes a thermal conductivity detector(TCD) and a 6 ft by 1/8 in. diameter column packed with Porapak Q. The analysis conditions of the gas chromatograph for the vapor sample was a TCD temperature of 200 oC, a column temperature of 50 oC, and a carrier gas flow rate of 20ml/min. The vapor sample was analyzed four times at each equilibrium point. The average of the individual compositions was considered as the equilibrium composition. The reproducibility of the vapor mole fraction was generally within ±0.001.

Initially, the apparatus was purged with N2 to remove remaining air and heated to the desired temperature. Then CO2 was carefully introduced into the equilibrium cell. It generally takes (8-10)h to reach equilibrium.

Results and Discussion

To verify the applicability of the experimental setup and the procedure used in this study, the solubility of CO2 in 15.3 wt% MEA aqueous solutions at 313.15K was measured at the partial pressure of CO2 ranging from 0.2 to 2000kPa and compared with the previously reported data I the literature. The solubility of CO2 in AHPD aqueous solutions at various conditions (temperature, 313.15, 323.15, and 333.15 K; concentration, 10 and 20 wt%; CO2 partial pressure, 0.2∼2000 kPa is presented in Figures 1-3. It is found that the the solubility of CO2 in AHPD is the highest among various amines at high pressure.

Conclusion

The solubility of CO2 in AHPD aqueous solutions was measured in the temperature range of 313.15 to 333.15K and in the concentration range of 10 and 20 wt%. The tendency of the solubility of CO2 in AHPD aqueous solution was found to be similar to that in MDEA solution.

Acknowledgment

This work was supported by Grant 2000-C-CD02-P-01 from the Korea Energy Management Corporation R&D Headquarter and also partially by the Brain Korea 21 Project.

Reference

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

2. Tontiwachwuthikul, P.; Meisen, A.; Lim, C. J. Solubility of CO2 in 2-Amino-2-methyl-1-propanol. J. Chem, Eng. Data 1991, 36, 130-133.

3. Li, M.-H.; Chang, B.-C. Solubilities of Carbon Dioxide in Water + Monoethanolamine + 2-Amino-2-methyl-1-propanol. J. Chem, Eng. Data 1994, 39, 448-452.

Figure 1. Solubility of Carbon Dioxide in 10wt% THAM Aqueous Solutions:

(○)313.15K; (▲)323.15K; (▽)333.15K.

Figure 2. Solubility of Carbon Dioxide in 10wt% and 20wt% THAM Aqueous Solutions at 333.15K: (▽)10wt%; (●)20wt%.

Figure 3. Solubility of Carbon Dioxide in 10wt% various amine Aqueous Solutions:

(○)AHPD; (●)AEPD; (▽)AMPD (▲)MEA