Vraag 4/ Question 4 [18] The importance of diffusion in catalyst particles can often be determined by measuring the effect of pellet size on the observed reaction rate. In this problem, consider an irreversible first-order reaction occurring in catalyst pellets where the surface concentration of reactant A is CAS = 0.15 M. The results that are obtained from 8 experiments in a spinning basket reactor, where the observed reaction rate per volume of catalyst (obs) is obtained as a function of the catalyst particle diameter (Deat), is given in TableP4. Assume that spherical particles were used. Table P4: Observed reaction rate as function of catalyst diameter Tobs (mol h cm) 0.6 1.2 2.3 3.6 Experiment 1 2 3 4 5 6 7 8 Dcat (cm) 4.0 2.0 1.0 0.60 0.20 0.050 0.0020 0.0010 9 14 15 15 Exp. 1-5 a) Motivate which experiments are affected by internal diffusion limitations. (2) b) Determine the intrinsic rate constant (k) and the effective diffusivity (De). Also prepare a figure (Excel) of the observed reaction rate as a function of the particle diameter, where the experimental data is compared to your modelled data using the obtained values for k1 and De. |k = 27.8 s, D = 2.0.106 m s (13) c) If internal diffusion was not affecting the reaction rate, what reaction rate was obtained in Experiment 1? 15 mol h cm- (3) TOTAL/TOTAAL: 80

Vraag 4/ Question 4 [18] The importance of diffusion in catalyst particles can often be determined by measuring the effect of pellet size on the observed reaction rate. In this problem, consider an irreversible first-order reaction occurring in catalyst pellets where the surface concentration of reactant A is CAS=0.15M. The results that are obtained from 8 experiments in a spinning basket reactor, where the observed reaction rate per volume of catalyst (robs) is obtained as a function of the catalyst particle diameter (Dcat), is given in TableP4. Assume that spherical particles were used. Table P4: Observed reaction rate as function of catalyst diameter Exp. 15 a) Motivate which experiments are affected by internal diffusion limitations. (2) b) Determine the intrinsic rate constant (k1) and the effective diffusivity (De). Also prepare a figure (Excel) of the observed reaction rate as a function of the particle diameter, where the experimental data is compared to your modelled data using the obtained values for k1 and De. k1=27.8s1,De=2.0106m2s1 c) If internal diffusion was not affecting the reaction rate, what reaction rate was obtained in Experiment 1? TOTAL/TOTAAL: 80