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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

    Stable and reusable hierarchical ZSM-5 zeolite with superior performance for olefin oligomerization when partially coked

    by Mohamed, Parsapur, Hita, Cerrillo, Ramirez, Huang, Castaño
    Appl. Catal. B: Environ. Year: 2022 DOI: https://doi.org/10.1016/j.apcatb.2022.121582

    Abstract

    The character of coke is typically regarded as a “deactivator” in zeolite catalysis. We report the interdependence of coke nature and location with its true character in the mechanisms of ethylene oligomerization: a model zeolite catalyzed transformation involved in many sustainable processes. We prepared, characterized, and tested ZSM-5 zeolites of different diffusion paths and acidities, using polymeric-, organic-template, or template-free strategies and various Si/Al ratios. The results indicate that coke can improve the selectivity/yield of higher olefins and jet-fuel aliphatics, and this positive effect is better than modifying the number of acid sites. The molecular-level nature of these coke species is elucidated using high-resolution mass spectrometry. The “enhancer” character of the coke can be better exploited in polymeric templated (hierarchical) ZSM-5 zeolite because mesopores retain coke without critically affecting accessibility or causing deactivation. Furthermore, this catalyst is stable for at least 74 h on stream and in multiple reaction-regeneration cycles.

    Keywords

    OLG HCE