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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

    Implications of Co-Feeding Water on the Growth Mechanisms of Retained Species on a SAPO-18 Catalyst during the Methanol-to-Olefins Reaction

    by Valecillos, Hita, Sastre, Aguayo, Castaño
    ChemCatChem Year: 2021 DOI: https://doi.org/10.1002/cctc.202100124

    Abstract

    The dynamics of retained and deactivating species in a SAPO-18 catalyst during the methanol-to-olefins reaction have been followed using a combination of ex-situ and in-situ techniques in differential and integral reactors.The retained species were analyzed using extraction, in-situ FTIR and in-situ UV-vis spectroscopies combined with online product analysis (gas chromatography and mass spectrometry). The composition of the extracted soluble species was determined using gas chromatography-mass spectrometry and that of the insoluble species using high-resolution mass spectrometry. We observe a decrease in the formation and degradation rates of retained species when co-feeding water, whereas the extent of the decreases is the same across the entire spectrum of retained molecules. This indicates that co-feeding water unselectively quenches the formation of active and deactivating species. At the same time, the catalyst has an extended lifetime when co-feeding water due to the diffusion of species (particularly olefins) out of the SAPO-18 crystals, and subsequent growth of heavy polycyclic aromatic structures that imply less deactivation. These conclusions can be extrapolated to other MTO catalysts with relatively similar pore topology such as SAPO-34 or SSZ-13 structures.

    Keywords

    O2H CRE