INVESTIGATIONS OF HYDROGEN-SULFIDE SOLUBI LITY AND SIMULTANEOUS SOLUBILITY OF HYDROGEN-SULFIDE AND CARBON-DIOXIDE IN MIXTURES OF PROPYLENE CARBONATE AND TRIETHANOLOAMINE

Solubility of H2S in a new absorbent, propylene carbonate (WP) modifie d by triethanoloamine (TEA), was determined by a static method [1]. Th e measurements were carried out in the temperature range of 10-40 degr ees C at partial pressure of gases up to 1.1 bar and TEA concentration range of 0-10% wt. The results are shown in Figs 1-4 in the form of d iagrams of solubility cr vs. partial pressure p. The functions p(H2S) = f(alpha) are linear for pure WP like for physical absorption, while for WP/TEA mixtures they show deviations from the Henry's law. Additi on of TEA to WP increases significantly the solubility of H2S (Table 4 ).The solubility of H2S in WP has been correlated with temperature and H2S partial pressure (Eq. (1)); the solubility of H2S in WP/TEA has b een correlated with temperature, H2S partial pressure and TEA concentr ation (Eq. (2)). On the basis of the regular solutions theory for mixe d solvents and the Hildebrand-Scatchard equations ((3)-(5)), the solub ility parameter delta(TEA) was determined. This parameter changes sign ificantly both with temperature and TEA concentration. The H2S-WP/TEA system cannot be regarded as a regular one. Measurements of simultaneo us solubility of CO2 and H2S in WP with addition of 10% wt. of TEA hav e been carried out at 20 degrees C. The results are shown in Table 8. CO2 and H2S dissolve in WP/TEA mixtures independently. Addition of TEA to WP increases solubility of H2S to a higher degree than that of CO2 , especially at low temperatures (Figs. 5, 6), which enables one to in crease selectivity of absorption of H2S removed from the gas containin g also CO2.