Modelling and design of reactive absorption are based on the theoretical de
scription of the reaction and mass transport in multicomponent systems. The
multicomponent nature of these phenomena leads to complex process behaviou
r due to the superposition of many driving forces-multicomponent diffusion,
chemical interactions, convective flows, multicomponent thermodynamic inte
rplay, etc. For this reason, adequate theoretical description of multicompo
nent reactive systems calls for the application of the Maxwell-Stefan equat
ions and, further, for the use of coupled mass transfer equations together
with the relevant reaction kinetics. On this basis, a two-phase, gas-liquid
reactive system is considered and a general dynamic model is developed for
its design. Both the film and bulk reaction mechanisms are allowed for. Th
is dynamic rate-based approach leads to a system of partial differential eq
uations, which have to be discretized in the axial direction. The resulting
DAE system is solved numerically. As an application example, the reactive
absorption of sour gases in an air purification process with packed columns
is simulated. For this case, an additional account of the electrical poten
tial gradient is involved because of the presence of electrolytes. Simulati
on results are presented for the H2S scrubber with three liquid distributor
s and a structured packing section. For the validation of the model, pilot
plant steady state experiments were carried out at Thyssen Still Otto in Du
isburg, Germany. The simulation results are in good agreement with the expe
rimental data.