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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

    Activation of n-pentane while prolonging HZSM-5 catalyst lifetime during its combined reaction with methanol or dimethyl ether

    by Cordero-Lanzac, Martinez, Aguayo, Castaño, Bilbao, Corma
    Catal. Today Year: 2022 DOI: https://doi.org/10.1016/j.cattod.2020.09.015

    Abstract

    This work explores the synergies during combined reactions of n-pentane (nC5) with oxygenates (methanol or dimethyl ether, OX). The experimental runs have been carried out in a packed bed reactor at 500 °C, using a high silica HZSM-5 zeolite-based catalyst with different oxygenate-to-n-pentane (OX/nC5) ratios in the feed. A significant enhancement of the n-pentane conversion occurs for low OX/nC5ratios in the feed (0.1−0.25), especially when using dimethyl ether (DME). In addition, the presence of n-pentane reduces the rate of catalyst deactivation by coking during the conversion of oxygenates. These results have been explained on the grounds of a mechanistic interaction between the reactants: (1) the fast formation of methoxy and olefin intermediates from oxygenates, particularly from DME, could explain the promotion of n-pentane cracking, by facilitating the activation of the alkane by hydrogen transfer reactions; (2) the attenuation of deactivation during the conversion of oxygenates could be related to a lower extent of the arene cycle in the dual-cycle mechanism (limiting the polymethylbenzene formation). The analyses of used catalysts by means of temperature-programmed oxidation and confocal fluorescence microscopy have pointed out the higher reactivity of DME than that of methanol also for yielding coke structures.

    Keywords

    O2H CHA