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Controlling selectivity and stability of zeolite catalysts for methanol to hydrocarbons and ethylene oligomerization


    Problem Statement

    Olefins are commodity chemicals with applications in the production of plastics (petrochemical industry), lubricants, plasticizers, and surfactants, among many others. However, there is an imbalance between their production and demand, which oligomerization-cracking reactions over zeolites could solve. At the same time, zeolites are excellent catalysts for methanol to hydrocarbons (MTH), olefins (MTO), or aromatics (MTA). The processes aim to produce light hydrocarbons like propylene or convert ethylene into higher-value a-olefins, aromatic hydrocarbons (BTX), and jet fuel.

    Our focus in this project is to modify, synthesize, and develop novel materials of different porosity (engineered at the multiscale): from hierarchical zeolites, nano zeolites, and hollow zeolites to catalytic particles, bodies, spray-dried, and extrudates with tuned properties. Additionally, we incorporate different metals (i.e., Ni, Cr, Zn) to adjust the selectivity of desired products.

    We use various reactors, such as operando or high-throughput packed-bed and batch reactors.

    OLG-O2H

    Goals

    • Control structure–selectivity: Tune zeolite porosity and acidity to maximize propylene and α-olefin yields.
    • 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

    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