(314g) Kinetic Modeling of Ethene Oligomerization over Bifunctional Ni-Exchanged Acid Zeolites

Ethene oligomerization is receiving increased research attention due to increasing domestic production of ethene and continued global demand growth for commodity chemicals and liquid fuels. The regional variations in shale gas composition and consumer product demand require an ethene oligomerization catalyst capable of producing a range of products. Ni-exchanged acidic zeolites combine homogenous-like active nickel sites and heterogenous-like acid sties to allow for ethene oligomerization using a solid support. The oligomerization process of ethene is characterized by a complex reaction network and leads to a broad product distribution. Computational methods are essential for developing a reaction mechanism and to solve the corresponding reactor design equations. In this work, a kinetic model is developed to describe ethene oligomerization on Ni and acid sites, supported by density functional theory (DFT) and experimental data. Mechanistic steps and reaction networks were generated to include each elementary reaction taking place on the catalyst. Reaction rates were expressed using elementary rate laws based on reaction families and DFT calculations. The model simulations were compared to experimental data to validate its accuracy. This model can be used to uncover dominant reaction pathways, reproduce experimental results, and ultimately to tune Ni-to-acid site ratios and their contributions to observed reaction pathways, to maximize production of high-value hydrocarbons that meet local market demand. By tuning the contributions of both Ni and acid sites, the product distribution can be adjusted to meet the real-time needs of the local petrochemical market, whether that be linear-alpha olefins or liquid fuels.