(95e) Optimizing Methanol Synthesis - from Lab to Industrial Plants Via High-Fidelity Modeling

To balance the number of experiments and still preserve meaningfulness of a kinetic model [1], a design-of-experiment based approach was taken. We carried out temperature scanning experiments of catalyst pellets at varying pressures and synthesis gas compositions in a gradient-free internal recycle reactor (Berty type) to obtain quasi-stationary measurements of catalyst productivity at industrially relevant operating conditions.

In order to evaluate these data, a gRPOMS model of the experimental setup was set up and validated. Core of this approach is a micro-kinetic model combined with a representation of the mass transport in the pellet and reactor characteristics. Using a log-likelihood based optimizer 10 kinetic parameters involving rate factors of MeOH synthesis and the rWGS, adsorption constants and respective activation energies was carried out resulting in a predictive, heterogeneous catalyst model of high accuracy.

This catalyst model can be integrated in a process model of an industrial MeOH process using additional considerations on mass and heat transfer processes. The acquired plant model is subsequently used to evaluate and optimize performance of a large scale plant. Results can be used to identify catalyst and process parameters that would increase the overall process productivity under industrial conditions.

1. G.H. Graaf, E.J. Stamhuis, A.Beenackers, Chem.Eng.Sci. 43 (1988), 3185-3195.