Non-isobaric adsorption analysis of SO 2 on molecular sieve 13X and activated carbon by dynamic technique

Abstract

Sulfur dioxide is one of the major pollutants resulting from fuel combustion. In this study non-isobaric pulse chromatography was used for the investigation of the adsorption properties of sulfur dioxide on molecular sieve 13X and activated carbon. The experimental procedure consists of introducing a pulse of sulfur dioxide on the inlet of a column packed with molecular sieve 13X and activated carbon adsorbents and measuring the concentration versus time response peak leaving the other end of the column. Adsorption equilibrium constants were calculated using the moment analysis of the chromatographic peaks. Non-isobaric pulse chromatographic technique necessitates the use of high carrier gas flow rates which avoids the tailing of the response peaks and reduces considerably the uncertainty in the measurement of the moments. The adsorption of sulfur dioxide was investigated in a temperature range of 353–453 K with the activated carbon, which is a typical temperature range of desulfurization of flue gas, and in a temperature range of 523–673 K with molecular sieve 13X. Adsorption equilibrium constants of sulfur dioxide were found to decrease considerably with increasing temperature. At 453 K, the adsorption equilibrium constant was found to be 18.78, whereas it has a value of 330.2 at 353 K with the activated carbon. At 673 K, the adsorption equilibrium constant was found to be 11.52, whereas it has a value of 167.82 at 523 K with molecular sieve 13X. Heat of adsorption of sulfur dioxide on molecular sieve 13X and the activated carbon was determined as −12.4 and −8.99 kcal mol −1, respectively.