THE ENHANCEMENT OF GAS ABSORPTION BY A HETEROGENEOUSLY CATALYSED CHEMICAL REACTION IN A STAGNANT LIQUID: TEMPERATURE RISE AND EFFECTIVENESS OF THE CATALYST

In the present paper a model has been developed to calculate the enhancement efficiency e of the gas absorption and the effectiveness factor η of the catalyst for a chemically reacting system consisting of a sedimented catalyst particles-containing layer of thickness γ_k adhering to the surface of a gas bubble situated in a stagnant liquid. This model predicts that for a heterogeneously catalysed first-order chemical reaction an increase in the thickness γ_k of the catalyst particles-containing layer will result in an increase of ε and a decrease of η. It has been shown that the optimum value (γ_k)_opt of this layer can be obtained from the relation (γ_k) = (D_AB/k₁₃). Further, a model is derived to calculate the steady-state temperature profile in the catalyst particles-containing layer adhering to the gas bubble surface. Both models have been applied to experimental results published in some of our previous papers. These experimental results concern the enhancement of the gas-absorption rate from a single hydrogen-containing gas bubble to a stagnant aqueous hydroxylaminephosphate-containing solution when a layer of sedimented Pd/C catalyst particles was adhered to the surface of the gas bubble. The model and the experimental results mentioned may approximately be considered as representative of slurry reactors in which finely divided catalyst particles show considerable adhesion to rising gas bubbles.