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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

    Differences among the Deactivation Pathway of HZSM-5 Zeolite and SAPO-34 in the Transformation of Ethylene or 1-Butene to Propylene

    by Epelde, Ibanez, Aguayo, Gayubo, Bilbao, Castaño
    Micorp. Mesopor. Mat. Year: 2014

    Abstract

    The deactivation of HZMS-5 and SAPO-34 catalysts has been studied in the transformation of ethylene and 1-butene under propylene intensification conditions. The deterioration of spent catalysts’ physical properties have been quantified and coke has been characterized by TPO and by several spectroscopic techniques (Raman, 13C NMR, FTIR, FTIR-TPO), in order to determine the effect reaction medium composition and the severity of catalyst shape selectivity have on the nature and location of the coke in the porous structure. The results reveal that the mechanism for coke deactivation consists of two steps: one for the formation of alkylated aromatics by oligomerization and another for the coke growth-condensation. The first step is analogous for both catalysts and it principally depends on the catalyst acid strength and acid site density. The second step is different for both catalysts: the microporous structure of SAPO-34, with cavities in the intersections, inhibits the diffusion of alkylated aromatics towards the outside of the structure, thus blocking active acid sites; whereas, HZSM-5 structure, with a high connectivity and without cavities, favors the diffusion of the aromatics that evolve for a longer time outside of the micropores. At process conditions, the results demonstrate that the coke formation is faster from ethylene than from 1-butene, due to the lower reactivity of ethylene for oligomerization-cracking mechanisms as well as its higher capability for coke formation.

    Keywords

    HCE OLG