적외분광법과 크로마토 측정기법을 이용한 초임계 이산화탄소 중에 희석시킨 유기용매의 흡착특성

진도원; 김영일; 박동원

Journal of the Korean Industrial and Engineering Chemistry, Vol.9, No.1, 76-81, February, 1998

Adsorption Characteristics on Organic Solvents Diluted in Supercritical Carbondioxide Measured by Chromatography nd IR Spectroscopy

진도원, 김영일, 박동원

초록

초임계 CO₂중에 미량 희석된 아세톤의 실리카겔(SG800, 세공경 nm, 입자경 10μm)표면에서의 물리적인 흡착현상을 FTIR 측정기법에 의해 측정하여, 그 결과를 크로마토그래피 측정기법을 이용해 얻어진 흡착현상과 비교하였다. 크로마토 측정기법에 의해 얻어진 흡착등온선(온도 313K, 압력 1MPa∼15MPa)은 CO₂의 임계압력(7.28MPa) 보다 낮은 압력에서 최대값을 가지며, 압력이 증가함에 따라 감소하는 경향을 보여준다. 이 결과는 아세톤과의 수소결합 형성에 의해 적색변위(red-shift, 흡착피크가 낮은 파수 영역으로 이동하는 현상)한 실리카겔 표면 OH기의 IA(Integral Absorbance, 적분강도)의 압력의존성과 정성적으로 일치한다. 그러나 초임계유체 영역에서의 크로마토 측정기법에 의한 흡착등온선의 압력증가에 따른 감소비가 FTIR 측정기법에 의한 IA 곡선의 압력증가에 따른 감소비에 비해 조금 크게 감소하는 경향을 보여준다. 이 결과는 비교적 약한 상호작용을 가지는 van der Waals 결합력과 상대적으로 강한 흡착력을 가지는 수소결합력이 실리카겔 표면에서의 아세톤의 흡착에 동시에 영향을 미치고 있다는 것을 나타낸다. 초임계 CO₂와 N₂ 가스중에 미량 희석된 트리에틸아민의 FTIR 실험결과로부터 실리카겔 표면에 흡착된 아민류 유기용매의 독특한 분광학적 흡착특성, 흡착띠(band)가 1300cm^-1 부근까지 적색변위하는 특성을 발견할 수 있었다.

Physical adsorption on a silica gel(pore size of 80 nm, particle size of 10 μm)has been studied for binary mixture of acetone diluted in CO₂ by use of a FTIR transmission technique and we have compared the result of FTIR transmission technique with that of a chromatographic technique. Measurements were made at 313.2 K and under pressures up to 15MPa. As the pressure increases from 0.1MPa, the IA(Integral Absorbance) of the hydrogen-bonded OH groups interacting with acetone and adsorbed amount bw use of a chromatographic technique increases at first, and reaches a maximum at a pressure below the critical pressure of CO₂, and then the intensities decrease gradually with increasing pressure. It is found that the pressure dependency of the chromatographic isotherm is a little larger than that of spectroscopic isotherm in the supercritical fluid region. This difference might be attributable to the weaker van der Waals force and relatively stronger hydrogen-bonding force influencing the adsorption of acetone on the sllica gel. The unique spectroscopic characteristics of amine group which vibrational frequencies of hydroxyl groups on the silica gel surface shift downward to about 1300 cm_-1) were measured from expermental result of triethylamine diluted in CO₂ or N₂.

[References]

Lochmuller CH, Mink LP, J. Chromatogr., 409, 55 (1987)
Tan CS, Liou DC, Ind. Eng. Chem. Res., 29, 1412 (1990)
Shojibara H, Sato Y, Takishima S, Masuoka H, J. Chem. Eng. Jpn., 28(3), 245 (1995)
Nitta T, Yoneya J, J. Chem. Eng. Jpn., 28(1), 31 (1995)
Shigeta T, Yonera J, Nitta T, Mol. Simul., 16, 291 (1996)
Fulton JL, Yee GG, Smith RD, J. Am. Chem. Soc., 113, 8327 (1991)
Gupta RB, Combes JR, Johnston KP, J. Phys. Chem., 97, 707 (1993)
Little LH, "Infrared Spectra of Adsorbed Species," Academic Press, New York (1966)
Hair ML, "Infrared Spectroscopy in Surface Chemistry," Marcel Dekker, New York (1967)
Urban MW, "Vibrational Spectroscopy of Molecules and Macromolecules on Surfaces," John Wiley & Sons, New York (1993)
Nitta T, Yakushijin Y, Kametani T, Yakushijin T, Kametani T, Katayama T, Bull. Chem. Soc. Jpn., 63, 1365 (1990)
Conder JR, Young CL, "Physicochemical Measurement by Gas Chromatography," Chapter 9, New York, USA (1979)
Herzberg G, "Molecular Spectra and Molecular Structure, vol. II, Infrared and Raman Spectra of Polyatomic Molecules," Van Nostrand Reinhold (1945)
Pelmenschiko AG, Morosi G, Gamba A, Zecchina A, Bordiga S, Paukshtis EA, J. Phys. Chem., 97, 1979 (1993)
Cant NW, Little LH, Can. J. Chem., 42, 802 (1964)
Cremer E, Huber H, Angew. Chem., 73, 461 (1961)

[1] Lochmuller CH, Mink LP, J. Chromatogr., 409, 55 (1987)

[2] Tan CS, Liou DC, Ind. Eng. Chem. Res., 29, 1412 (1990)

[3] Shojibara H, Sato Y, Takishima S, Masuoka H, J. Chem. Eng. Jpn., 28(3), 245 (1995)

[4] Nitta T, Yoneya J, J. Chem. Eng. Jpn., 28(1), 31 (1995)

[5] Shigeta T, Yonera J, Nitta T, Mol. Simul., 16, 291 (1996)

[6] Fulton JL, Yee GG, Smith RD, J. Am. Chem. Soc., 113, 8327 (1991)

[7] Gupta RB, Combes JR, Johnston KP, J. Phys. Chem., 97, 707 (1993)

[8] Little LH, "Infrared Spectra of Adsorbed Species," Academic Press, New York (1966)

[9] Hair ML, "Infrared Spectroscopy in Surface Chemistry," Marcel Dekker, New York (1967)

[10] Urban MW, "Vibrational Spectroscopy of Molecules and Macromolecules on Surfaces," John Wiley & Sons, New York (1993)

[11] Nitta T, Yakushijin Y, Kametani T, Yakushijin T, Kametani T, Katayama T, Bull. Chem. Soc. Jpn., 63, 1365 (1990)

[12] Conder JR, Young CL, "Physicochemical Measurement by Gas Chromatography," Chapter 9, New York, USA (1979)

[13] Herzberg G, "Molecular Spectra and Molecular Structure, vol. II, Infrared and Raman Spectra of Polyatomic Molecules," Van Nostrand Reinhold (1945)

[14] Pelmenschiko AG, Morosi G, Gamba A, Zecchina A, Bordiga S, Paukshtis EA, J. Phys. Chem., 97, 1979 (1993)

[15] Cant NW, Little LH, Can. J. Chem., 42, 802 (1964)

[16] Cremer E, Huber H, Angew. Chem., 73, 461 (1961)