Solubility and mass transfer of CO and H 2 in Fischer—Tropsch liquids and slurries

Abstract

Solubilities C* and mass transfer coefficients k L a of CO and H 2 in three Fischer—Tropsch liquid fractions were measured as functions of temperature (373 – 523 K), pressure (1 – 4 MPa) and stirrer speed (800 – 1100 rev min −1) in a mechanically agitated and surface-aerated vessel. Measurements were carried out using a transient absorption techique. The solubilities of both CO and H 2 increase with temperature and pressure in the ranges examined; the solubilities of CO are 50% – 75% higher than those for H 2. It was found that C* can be expressed by Henry's law and for otherwise identical conditions it decreases with increasing carbon number of the liquid. In general, the mass transfer coefficients for CO and H 2 are of the same order of magnitude. The results indicate a dependence of k L a on temperature, pressure, stirrer speed and molecular weight of the liquid. The presence of solids decreases k L a significantly, but mix ing power strongly enhances k L a.