Light Hydrocarbon Adsorption and Oligomerization in Acidic and Ni-Acid Zeolites

Koninckx, Elsa

doi:https://doi.org/10.21985/n2-218e-qj68

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Light Hydrocarbon Adsorption and Oligomerization in Acidic and Ni-Acid Zeolites

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From energy to materials, hydrocarbon chemistry drives our world. Stemming from the petrochemical industry, our understanding of CxHy combinations has allowed society to flourish, and hydrocarbons will likely remain valuable species in our future even as we transition to greener carbon and hydrogen sources. Currently, one of the most efficient ways of reacting hydrocarbons is through catalytic zeolites. Catalytic acid zeolites are commonly used in the petrochemical upgrading process. More complex zeolites can be made through the ion-exchange of an acidic zeolite to introduce metals, specifically, nickel (Ni) into the framework. These catalytic zeolites are less studied than acidic zeolites but provide two interacting active sites for unique chemistry. Ni-acid zeolites have shown intriguing results for ethene oligomerization, with product distributions reminiscent of both a homogenous Ni catalyst and a heterogenous acid catalyst. In this dissertation, computational methods are used to better understand the adsorption and oligomerization of light hydrocarbons in acidic (H+) and Ni-acid (Ni-H) zeolites. The first portion of this dissertation focuses on the adsorption of multiple hydrocarbons into acidic ZSM-5 or MFI zeolites using density functional theory (DFT). Adsorption is the first step in zeolite applications and a better understanding of these energies, specifically bi-molecular adsorptions, provides better insight into modeling of bimolecular reactions, like oligomerization. Thus, the next portion of this dissertation focuses on the oligomerization of ethene over a Ni-acid Beta zeolite. A review of the mechanism, the construction of the model, and further detailed investigations in the deactivation of ethene on Ni-acid Beta is discussed. Collectively, this dissertation demonstrates the ability to use computational tools to better understand how hydrocarbons and zeolites interact, furthering their use in our society.

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