The aerobic, water-assisted selective oxidation of methane over platinum-based catalysts
type: CreativeWork
description: The selective oxidation of methane to C1-oxygenates such as methanol, formaldehyde and dimethylether remains one of the grand challenges of catalysis chemistry, due to the difficulty in attaining high selectivities at high methane conversions. This has been attributed to the higher reactivity of methane oxidation products compared to methane itself, which therefore leads to their facile conversion to CO and CO2 [1]. Strategies that have been adopted to selectively convert methane include product protection (i.e. converting methane to a methylester, which is stable against further oxidation compared to methanol) [2, 3], cyclical methane oxidation using zeolites (i.e. stepwise activation of oxygen, methane and product extraction) [4, 5], the use of mild reaction conditions (i.e. conversion of methane at low temperature using hydrogen peroxide)[6, 7] and the use of copper-exchanged zeolites which enable the catalytic conversion of methane with high methanol selectivities [8-10]. Copper-exchanged zeolites require feeding an excess of methane and still suffer from low methane conversions. The study presented in this thesis is focused on investigating the aerobic, selective oxidation of methane over supported platinum-based catalysts in the presence of water, with the investigation focusing on a) the role of water, b) the effects of the support and c) the effects of alloying platinum on the catalytic activity and oxygenate selectivity. The effects of water were investigated initially in a gas-phase, fixed bed reactor that is equipped with a steam generator. Initial results from the selective oxidation of methane yielded CO2. Accidentally flooding the reactor resulted in the formation of selective oxidation products such as methanol, methoxymethanol and 1,3,5, trioxane, which were observed when the reactor was flooded on purpose. The experiments were then carried out in a specially-constructed trickle-bed reactor that enabled the co-feeding of liquid water. An increase in …
abstract: The selective oxidation of methane to C1-oxygenates such as methanol, formaldehyde and dimethylether remains one of the grand challenges of catalysis chemistry, due to the difficulty in attaining high selectivities at high methane conversions. This has been attributed to the higher reactivity of methane oxidation products compared to methane itself, which therefore leads to their facile conversion to CO and CO2 [1]. Strategies that have been adopted to selectively convert methane include product protection (i.e. converting methane to a methylester, which is stable against further oxidation compared to methanol) [2, 3], cyclical methane oxidation using zeolites (i.e. stepwise activation of oxygen, methane and product extraction) [4, 5], the use of mild reaction conditions (i.e. conversion of methane at low temperature using hydrogen peroxide)[6, 7] and the use of copper-exchanged zeolites which enable the catalytic conversion of methane with high methanol selectivities [8-10]. Copper-exchanged zeolites require feeding an excess of methane and still suffer from low methane conversions. The study presented in this thesis is focused on investigating the aerobic, selective oxidation of methane over supported platinum-based catalysts in the presence of water, with the investigation focusing on a) the role of water, b) the effects of the support and c) the effects of alloying platinum on the catalytic activity and oxygenate selectivity. The effects of water were investigated initially in a gas-phase, fixed bed reactor that is equipped with a steam generator. Initial results from the selective oxidation of methane yielded CO2. Accidentally flooding the reactor resulted in the formation of selective oxidation products such as methanol, methoxymethanol and 1,3,5, trioxane, which were observed when the reactor was flooded on purpose. The experiments were then carried out in a specially-constructed trickle-bed reactor that enabled the co-feeding of liquid water. An increase in …
author: Mahlaba, Sinqobile Vuyisile Lusanda
keywords: Chemical Engineering
date published: 2023
date modified: 2026-07-22T22:23:07Z
provider: University of Cape Town
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Department of Chemical Engineering

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property ID: Handle
value: http://hdl.handle.net/11427/39684