In this research, an experimental study coupled with a mathematical modeling for a modified pressure swing adsorption (PSA) technique is developed. In particular, solid grains are saturated with a liquid selective solvent of NMP (n-methyl-2-pyrolidone) to remove H2S from a gaseous mixture. Since, the solubility of H2S is very sensitive to the partial pressure above the layer of liquid, the saturated sorbent could be easily regenerated by sweeping its bed with nitrogen at ambient temperature and pressure. For this purpose, silica gel, NaY and HY zeolites were saturated with 141.8, 80.8 and 59 weight percent of solvent respectively. Operations with various adsorbents from 20 to 60°C at 600 kPa and from 100 to 600 kPa at 20°C were performed experimentally. Then, a mathematical model for this process including a set of partial differential equations was developed where LDF approximation for mass transfer and Henry’s isotherm were made use of. These equations were solved numerically. Obtained experimental breakthrough data were utilized to construct Henry’s constant through fitting sorption models. The best values for sorption (that is, adsorption) constants were empirically determined to be 0.970, 0.985 and 0.995 for silica gel, NaY and HY zeolites; respectively. Ultimately, amount of H2S sorption was calculated enabling description of desorption (that is, purging) step for this system with a set of partial differential equations. Thus, empirical desorption constant values of 0.744, 0.749 and 0.753 for silica gel, NaY and HY zeolites respectively, were determined through solving the related PDE.
Key words: H2S adsorption, pressure swing adsorption (PSA), mathematical model.
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