Model-Targeted Kinetic Experimentation for the Modeling of Industrial Ethylene Oxide Reactor

Ethylene oxide (EO), a precursor to ethylene glycol (EG), is produced via selective oxidation of ethylene with oxygen using an Ag supported on α-Al2O3 catalyst in the EO/EG plant located in the Petkim Petrochemical Complex, the only petrochemical manufacturer in Turkey. EO production process takes place in two parallel operating fixed-bed multi-tubular reactors at a temperature and pressure range of 240–260 °C and 17–18 bar, respectively. The main reaction is ethylene epoxidation reaction, whereas the ethylene and EO combustion reactions are undesired, lowering the product yield and increasing the associated CO2 emissions from the EO/EG plant. This study is aimed at the EO reactor model development using a model-targeted experimentation approach. The final goal is to deploy the model in real-time optimization of the EO reactor operation.

This presentation will focus on the rationale behind employing lab-scale kinetic experimentation to determine an appropriate kinetic mechanism for the catalyst used within the plant-scale EO reactor. The catalyst testing setup will be introduced, employing a crushed industrial catalyst in a lab-scale integral fixed-bed reactor. Preliminary experiments were carried out in order for eliminating heat and mass transfer limitations. DOE (Design of experiments) methodology coupled with custom-designed experiments were utilized for determining and planning the set of experiments as predicting the parameters within the kinetic mechanism which is the main interest. Data reconciliation is a key undertaking prior to kinetic model discrimination. gPROMS Process Builder with its Advanced Model Library for Fixed-Bed Reactors (AML:FBCR) is used to represent the experimental setup and perform parameter estimation activities. Finally, the most statistically significant kinetic model was discriminated against out of other candidates with the intention of using in the industrial reactor model.