Steady State Simulation of a Multi-Bed Adiabatic Reactor for Methanol Production

A one dimensional heterogeneous model accounting for intraparticle diffusion limitations is developed for methanol production from carbon oxides and hydrogen. The model and the kinetics used fit very will industrial data. The effect of the CO2/CO, (C02 + CO)/H2 mole ratios, inlet temperature, reaction pressure, size of the catalyst particle and the tortuosity factor on the reactor performance are investigated. The study indicates that the methanol reactor operation is highly sensitive to variations in the temperature

Catalyst deactivation and reactivation during aqueous alcohol oxidation in a redox-cycle reactor

Platinum catalyst deactivation during aqueous alcohol oxidation is discussed, using the oxidation of methyl -D-glucopyranoside as an example. The most important causes of platinum deactivation are catalyst over-oxidation and catalyst poisoning. Deactivation by over-oxidation can be reversed by applying a redox-cycle, i.e. cyclic exposure to oxidative and reductive circumstances. A kinetic model for methyl -D-glycopyranoside oxidation, platinum deactivation, and reactivation is presented and implemented into a three-phase stirred slurry reactor model, clearly showing the advantages of redox-cycles

CO oxidation over a supported Pt catalyst : transient kinetics using temporal analysis of products (TAP).

Pulse type transients were introduced in a TAP micro reactor filled with an inert quartz bed, with a porous SiO2 support, and with Pt/SiO2 catalyst. Under Knudsen conditions, rate parameters concerning diffusion of several noble gases and diffusion, adsorption, and desorption of reactants and products were detd. by nonlinear regression of the pulse responses. Only part of the intrapellet catalyst vol. interferes with the admitted pulses. Bed scale diffusivities might be approached with values for non porous pellets

Non-steady state operation of trickle-bed reactors.

A review with 12 refs.; in this contribution we discuss the opportunities of pulsing flow and a cycled liq. feed strategy, both resulting in a non-steady state behavior of the trickle-bed reactor. The focus is on the hydrodynamics and its effect on catalytic reactions is evaluated

Transient kinetics of ethylene and carbon monoxide oxidation for automotive exhaust gas catalysis: experiments and modelling

The transient oxidn. of ethylene by oxygen over a com. available Pt/Rh/CeO2/g-Al2O3 three-way exhaust gas catalyst is described. Expts. were carried out in a fixed-bed micro-reactor with two sep. inlets, enabling alternate feeding of ethylene and oxygen. The exptl. conditions were chosen so as to obtain intrinsic kinetics, i.e., in the absence of external and internal mass and heat transport limitations. Also, these conditions resemble the cold-start period of an Otto engine in a car. For these conditions, only total oxidn. of ethylene to carbon dioxide and steam was obsd. From the shape of the CO2 peaks, two types of adsorbed ethylene species seem to exist. The presence of ceria in the catalyst did not influence the ethylene oxidn. significantly at the investigated conditions. A kinetic model, based on elementary reaction steps, is presented, which can be combined with the model for transient carbon monoxide oxidn. on the same catalyst