(199d) Ethylene Oligomerization on H-BEA Zeolites: A Compact Microkinetic Model for a Complex Reaction Network

Transportation fuels consist of alkanes, cycloalkanes, olefins, and aromatics ^[1,2] and can be produced from shale gas-based ethylene via oligomerization reactions, accompanied by other reactions such as cyclization, aromatization, etc. This reaction network is highly complex, thus making it challenging to construct corresponding microkinetic models which are essential to optimize the reaction conditions to obtain maximum yields of fuel-type mixtures and minimum coke.

In this work, we build a compact microkinetic model for a highly complex reaction network for ethylene oligomerization on H-BEA catalyst, which captures production of various species such as paraffins, olefins, dienes, cyclic hydrocarbons and aromatics up to C10 compounds. This model is more complex than the already existing oligomerization models on H-BEA ^[3,4] which included lower rank products, non-cyclic paraffins and olefins. We use NetGen ^[5] to generate the network and apply a seeding strategy to prune this network of 10⁵ or more species down to one that has only 13.5k species. Further, we use a lumping technique to reduce the network to 700 species, whose concentrations are related to those of other species through thermodynamic equilibrium. We then parametrized the model using scaling relationships and fit a small number of parameters to capture experimental data. Through sensitivity analysis, this model can provide insights into various ‘kinetic knobs’ that can be tuned to optimize the yields of desired products and minimize coke.

References:

1. https://www.atsdr.cdc.gov/toxprofiles/tp72-c3.pdf
2. https://www.atsdr.cdc.gov/ToxProfiles/tp76-c3.pdf
3. Koninckx et al., Ind. Eng. Chem. Res.2022, 61, 3860−3876
4. Vernuccio et al., Journal of Catalysis 395 (2021) 302–314
5. Broadbelt et al., Eng. Chem. Res. 1994, 33 (4), 790–799