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Controlling the selectivity–stability tradeoff in zeolite catalysis: oligomerization–alkylation, cracking, and methanol-to-hydrocarbons 


    Problem Statement

    Olefins and aromatics are commodity chemicals used in producing plastics (in the petrochemical industry), lubricants, plasticizers, and surfactants, among other products. However, there is an imbalance between their production and demand, which reactions like oligomerization, alkylation, and cracking over zeolites could help address. At the same time, zeolites serve as excellent catalysts for converting methanol to hydrocarbons (MTH), olefins (MTO), or aromatics (MTA). These processes aim to produce light hydrocarbons such as propylene or to convert ethylene into higher-value alpha-olefins, aromatic hydrocarbons (BTX), and jet fuel.


    Our focus in this project is to synthesize, modify, and develop new catalysts with engineered porosity at multiple scales: from hierarchical and hollow zeolites to catalytic particles, bodies, or technical catalysts intended for implementation. Additionally, we incorporate various metals (e.g., Ni, Cr, Zn) to influence the selectivity toward the desired products.

    We utilize various reactors, including forced dynamic, operando, high-throughput packed-bed, and batch reactors.

    OLG-O2H

    Goals

    • Control the catalyst structure to balance selectivity and stability.
    • Metal modulation: Use Ni, Cr, Zn to bias reaction pathways and improve selectivity to target hydrocarbons.
    • Deactivation control: Reduce coke formation and extend catalyst lifetime with regeneration strategies.
    • Reactor optimization: Shape catalysts into bodies/extrudates and validate 100 h continuous stable operation.

    Related People

    Faseeh Kulangara Kandiyil
    Hend Omar Mohamed
    Kiruthika Jayaseelan

    Related Publications

    Highly productive framework bounded Ni2+ on hierarchical zeolite for ethylene oligomerization

    by Mohamed, Velisoju, Hita, Abed, Parsapur, Zambrano, Hassine, Morlanes, Emwas, Huang, Castaño
    Chem. Eng. J. Year: 2023 DOI: https://doi.org/10.1016/j.cej.2023.146077

    Abstract

    The production of higher linear olefins via ethylene oligomerization is an applied industrial process using homogeneous catalysts in the liquid phase. Heterogeneous catalysts based on Ni supported on zeolites are attractive materials for gas phase oligomerization but typically offer a low selectivity or low conversion. Here, we investigate a tailored method to introduce the Ni2+species within the hierarchical zeolite crystallization step (in situ) and compare it with the standard impregnation procedure (ex situ). The in situ engineered catalyst has a very high concentration of Ni2+ species, seamlessly inserted and well dispersed into the zeolite framework, with increased accessibility through meso- and micropores. This catalyst has a unique 1-butene cumulative productivity (32.7 g of 1-butene per g of catalyst) and stability for at least 48 h. This framework bounded Ni2+ promotes oligomerization over isomerization, cracking, and hydride transfer, while the hierarchical zeolite structure enables the discharge of coke precursors. These results pave the way for a more efficient and effective ethylene oligomerization process.

    Keywords

    OLG HCE