Transient effectiveness factor in porous catalyst particles. Application to kinetic studies with batch reactors

C. BIDABEHERE; J.R. GARCIA; U. SEDRAN

CHEMICAL ENGINEERING RESEARCH & DESIGN

INST CHEMICAL ENGINEERS

Año: 2017 p. 41 - 50

0263-8762

The actual transient characteristics of the effectivenessfactor for reactions in porous catalyst particles were considered in a modelfor kinetic studies in gradientless batch reactors. The transient effectivenessfactor depends both on the Thiele modulus and the system?s adsorption capacity,a function of the catalyst mass. After the injection of reactant, the transienteffectiveness factor reaches a stable value, which is always larger than theconventional factor based on the assumption of steady state in theconcentrations in the particle. The steady state approach on classicalpseudo-homogeneous models can be used if the adsorption capacity of the systemis low. A new pseudo-homogeneous model, where the accumulation of mass in theparticle and the transient effectiveness factor approach are considered, extendthis limit to systems with medium or high adsorption capacity. The usual interpretation of the Weisz-Prater parameter was reformulated based on this approach, showing that kinetic constantscan be determined preciselyif the transient effectiveness factor is employed, thus avoiding the errors induced bythe accumulation of mass in the catalyst particles. Properexperimental conditions for kinetic studies were suggested.