Chemical storage of solar energy—Kinetics of heterogeneous NH 3 and H 2SO 4 reactions I. Analysis of experimental reaction and mass transfer data

Abstract

The exothermic heterogeneous reaction of ammonia vapor and liquid sulfuric acid (H 2O + SO 3) to produce ammonium hydrogen sulfate and ammonium sulfate is important for the recovery of stored energy in the small molecules, H 2O, SO 3 and NH 3. As the first part of a chemical reaction engineering analysis, literature data on the reaction and mass transfer were analyzed. The reaction rate constant as a function of temperature and the mass transfer coefficient as a function of the dynamical variables in a flow system were determined. The reaction mechanism in concentrated liquid phase is pseudo-second order and the rate is extremely fast. However, for the heterogeneous system with ammonia transferred from the vapor phase the mass transfer is rate controlling. A broad range of mass transfer data, covering packed columns and dispersed phase droplets, was correlated over 15 orders of magnitude by the j D -factor correlation method.