Enhancing propane dehydrogenation: Insights into oxidative dehydrogenation and total oxidation pathways

Almoteiry, Ahlam 2023. Enhancing propane dehydrogenation: Insights into oxidative dehydrogenation and total oxidation pathways. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Oxidative dehydrogenation and total oxidation reactions were studied over supported Pt catalysts. The study employed the co-precipitation method to prepare the supports, and the SEA (Strong Electrostatic Adsorption) method to prepare PtOX-based catalysts with low platinum loadings. The role of the support was examined by comparing CeO2 to ZrO2, TiO2, and SiO2 for oxidative dehydrogenation (ODH), direct dehydrogenation (PDH), and total oxidation. Catalyst activity varies depending on the reaction mechanism and catalyst properties. Several factors influence the catalytic activity, selectivity, and yield of each reaction such as reducibility, dispersion, oxidation state, and particle size which H2-TPR, cochemisorption, XPS, XRD, and TEM can determine. After preliminary screening of several supported Pt catalysts in propane ODH, Pt/CeO2 was identified as a promising candidate with high activity. Propene selectivity can be improved by modifying catalytic test conditions or adding promoters to Pt catalysts. The high reducibility for Pt/CeO2 can increase the activity of propane, while low reducible catalysts (Pt/ZrO2 and Pt/TiO2) show better propene selectivity compared to Pt/CeO2. Following this, catalytic activity improvement was investigated by testing Pt catalysts in the presence of excess air and propane at moderate temperatures. This was done following the total oxidation mechanism. Several characterisation methods showed that Pt particle size and oxidation state can explain the catalytic activity. The presence of metallic Pt active sites on catalyst surfaces relates possibly to their large particle size. This can increase catalyst activity in this mechanism. Furthermore, the addition of promoters (Mn and K) to Pt/CeO2 and Pt/SiO2 was investigated to assess the impact of promoters on the ODH of propane. Adding a small concentration of promoters improved the yield of propene, with Pt and Mn promoters on CeO2 giving the best yields.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Chemistry
Date of First Compliant Deposit:	30 May 2024
Last Modified:	30 May 2024 15:54
URI:	https://orca.cardiff.ac.uk/id/eprint/169301

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