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Ce_xZr_1-xO₂-Supported C_rO_x Catalysts for CO₂-Assisted Oxidative Dehydrogenation of Propane – Probing the Active Sites and Strategies for Enhanced Stability

Lookup NU author(s): Dr Kui Zhang, Professor Adam Harvey

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Abstract

© 2022 American Chemical Society.CO2-assisted oxidative dehydrogenation of propane (CO2-ODH) represents an attractive approach for propylene production and CO2 utilization. As a soft oxidant, CO2 can minimize overoxidation of the hydrocarbons to enhance the propylene selectivity while increasing the equilibrium yield. However, a major challenge of CO2-ODH is the rapid deactivation of the catalysts. The current study focuses on designing CexZr1-xO2-mixed oxide-supported CrOx catalysts for CO2-ODH with enhanced product selectivity and catalyst stability. By doping 0-30% Ce in the CexZr1-xO2 mixed oxide support, propane conversion of 53-79% was achieved at 600 °C, with propylene selectivity up to 82%. Compared to the pure ZrO2-supported catalyst (i.e., 5 wt %Cr/ZrO2), 20-30 %Ce doped catalysts (i.e., 5 wt %Cr/Ce0.2Zr0.8O2 and 5 wt %Cr/Ce0.3Zr0.7O2) inhibited the formation of CH4 and ethylene and improved propylene selectivity from 57 to 77-82%. Detailed characterizations of the 5%Cr/Ce0.2Zr0.8O2 catalyst and density functional theory (DFT) calculations indicated that Cr3+ is the active species during the CO2-ODH reaction, and the reaction follows a non-redox dehydrogenation pathway. Coke formation was determined to be the primary reason for catalyst deactivation, and the addition of Ce to the ZrO2 support greatly enhanced the coke resistance, leading to superior stability. Coke removal by oxidizing the catalyst in air is effective in restoring its activity.

Publication metadata

Author(s): Dou J, Funderburg J, Yang K, Liu J, Chacko D, Zhang K, Harvey AP, Haribal VP, Zhou SJ, Li F

Publication type: Article

Publication status: Published

Journal: ACS Catalysis

Year: 2023

Volume: 13

Issue: 1

Pages: 213-223

Print publication date: 06/01/2023

Online publication date: 13/12/2022

Acceptance date: 02/12/2022

ISSN (electronic): 2155-5435

Publisher: American Chemical Society

URL: https://doi.org/10.1021/acscatal.2c05286

DOI: 10.1021/acscatal.2c05286

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