Deactivation of a lanthanum exchanged zeolite Y catalyst for isopropyibenzene (cumene) cracking was studied with a thermobalance. The kinetics of coke formation and the main reaction were determined. The Froment-Bischoff approach to modeling catalyst deactivation was used. The deactivation function giving the best fii to both the cracking and coking reaction data was an exponential one related to the coke content of the catalyst. The kinetic mechanism for coking that gave the best fit was one in which parallel and consecutive coking reactions occurred simultaneously. Apparently, more coke forms from products than reactants, especially at higher temperature.

Hydrodenitrogenation (HDN) of hetero-nitrogen compounds in petroleum crudes and synthetic liquids derived from oil shale and coal is studied using quinoline as a model nitrogen compound and benzene as a diluent. Both the external and internal mass-transfer rates in the Ni-W Y-type zeolite have been calculated in order to determine the possibility of diffusion limitations. Kinetic data were taken from a continuous flow Berty-type reactor at 34-72 bar, 350-460 °C, and hydrogen mole fraction from 25% to 90%. Hydrogenation of benzene solvent is negligible unless the nitrogen reactant is highly denitrogenated. Catalyst deactivation and reactivation occurred during the experimental operations. A Langmuir-Hinshelwood model was used to account for kinetic behavior, and the Redlich-Kwong equation of state (EOS) was used to consider nonideal gas behavior. A prediction algorithm based on the simplification of the HDN network reproduced the experimental data well.

The reoxidation of a nickel catalyst was investigated by means of an electrobalance. A model discrimination study led to a homogeneous gas-solid reaction model with a Hougen-Watson rate expression. Simulation of the industrial reoxidation of a nickel reforming catalyst was made through a transient reactor model with interfacial gradients. The effects of various parameters on adiabatic temperature rises were examined.

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This study uses the kinetics developed for cumene cracking to simulate cracking and coking in a fixed bed. The Froment-Bischoff method for modeling catalyst deactivation was used. The simulations suggest significant coke profiles along the reactor length. This result is in disagreement with the "time-on-stream" method of modeling catalyst deactivation. Time-on-stream would predict a uniform deactivation in a tubular isothermal reactor since its deactivation equation does not include the local concentration of reacting species. Comparisons are made with experimental data for catalytic cracking cumene and hexadecane in fixed beds.

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