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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

    Direct analysis at temporal and molecular level of deactivating coke species formed on zeolite catalysts with diverse pore topologies

    by Hita, Mohamed, Yerrayya, Zambrano, Zhang, Ramirez, Castaño
    Catal. Sci. Technol. Year: 2023 DOI: https://doi.org/10.1039/D2CY01850K

    Abstract

    he mechanistic understanding of coke formation on zeolites is elusive, given the limitations for the extraction and analysis of coke species. Here, we analyze the evolution of deactivating coke species over time on the surface of Ni/ZSM-5, β and Y zeolites during ethylene oligomerization, which is a representative coke-forming reaction. We present a method that directly analyzes the coke species using high-resolution mass spectrometry on the used catalysts and their isolated soluble and insoluble coke fractions (indirect analysis). Along with other techniques, we report a full-picture temporal evolution of coke and its fractions at the molecular level to establish a correlation between the dominant reaction mechanisms, the location of coke within the catalyst structure, and the observed performance of the catalysts. Ab initio calculations are performed to understand the preferable location of coke. We delve deep into the peculiar deactivation mechanism of ZSM-5 zeolite (MFI structure), which shows two less intuitive parallel deactivation pathways.

    Keywords

    OLG ANW