Thesis Format
Integrated Article
Degree
Doctor of Philosophy
Program
Chemical and Biochemical Engineering
Collaborative Specialization
Environment and Sustainability
Supervisor
de Lasa, Hugo
Abstract
This study investigates the performance of fluidizable VOx/MgO-γAl2O3 catalysts for producing C4-olefins through n-butane oxidative dehydrogenation (BODH). Catalysts were prepared using vacuum incipient wetness impregnation and characterized through a variety of analytical methods, including BET (Brunauer–Emmett–Teller) for surface area, XRD (X-ray diffraction), LRS (laser Raman spectroscopy), and XPS (X-ray photoelectron spectroscopy) to confirm the presence of amorphous VOx phases. Additional analyses—TPR/TPO (temperature-programmed reduction/oxidation), NH3-TPD (temperature-programmed desorption), NH3-desorption kinetics, and pyridine-FTIR—assessed catalyst stability, acidity levels, and metal-support interactions. The fluidizable catalysts were evaluated in a fluidized CREC Riser Simulator under anaerobic conditions, with reaction times ranging from 10 to 20 seconds and temperatures between 475°C and 550°C. Among the catalysts studied, the 5 wt% V-doped MgO-γAl2O3 demonstrated the highest selectivity for C4-olefins (82%-86%) and a butane conversion rate of 24%-27% at 500°C with a 10 second reaction time. After six BODH cycles, catalyst regeneration and coke formation were analyzed using Total Organic Carbon (TOC). The study also developed a kinetic model for the BODH reaction using a VOx/MgO−γAl2O3 catalyst containing 5 wt% V. This model, which applies Langmuir-Hinshelwood kinetics incorporating reactions such as cracking, oxydehydrogenation, and complete oxidation, achieved optimal C4-olefin selectivity of 86% at 500°C and 10 seconds. The kinetic parameters were precisely defined, showing narrow confidence intervals and minimal cross-correlation, highlighting the catalyst’s compelling performance and stability under the tested conditions.
Summary for Lay Audience
This study focuses on developing and testing special catalysts to produce C4-olefins, important chemicals used in manufacturing, from n-butane through a process called oxidative dehydrogenation (BODH). C4-olefins are essential building blocks for materials like rubber, plastics, and fuels. The key challenge in this process is to find catalysts that can efficiently convert n-butane to C4-olefins while minimizing unwanted by-products. The research investigates different fluidizable catalysts made from vanadium (VOx), magnesium oxide (MgO), and alumina (γAl2O3). The catalysts were tested in a special reactor (fluidized CREC Riser Simulator) under specific conditions— temperatures (475°C to 550°C) and short reaction times (10 to 20 seconds)—to simulate real industrial settings. Among the catalysts, the one containing 5% vanadium on a MgO-Al2O3 base showed the best performance, converting up to 27% of the n-butane and achieving a high selectivity for C4-olefins (82% to 86%). Additionally, the research developed a mathematical model to describe the reaction process and predict outcomes under different conditions. This model successfully predicted the best reaction conditions for maximizing C4-olefins production while minimizing waste. Overall, the study provides valuable insights into the potential of these catalysts to improve the efficiency of BODH, contributing to cleaner and more efficient production of essential chemicals.
Recommended Citation
BIN SULAYMAN, ABDULHAMID, "Catalytic Oxidative Dehydrogenation of N-Butane under Oxygen-Free Reaction Conditions in a Fluidized CREC Riser Simulator: Reactivity, Kinetic Modelling" (2024). Electronic Thesis and Dissertation Repository. 10649.
https://ir.lib.uwo.ca/etd/10649
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
