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Today, humanity has two major priorities that are often linked: finding a new energy resource and controlling the global warming. Among the different available energy sources, natural gas (NG) as methane is the most abundant. Its proven world reserves are steadily increasing and currently correspond to the estimation of world crude oil resources.
However, the difficulty of methane transporting hampers the development of its international trade. For example, the NG transport requires liquefaction of the gas at about -160°C at atmospheric pressure. This solution is preferred over great distances but unfortunately it is expensive and unprofitable. Consequently, in several cases, millions of tonnes of methane are burned on site or released into the atmosphere due to the high cost of the storage and transport process.
In this context, a chemical conversion of methane into a liquid product, such as methanol, formaldehyde or gasoline, is one of the most promising solutions for a better exploitation of this gas. Nevertheless, the major challenge is that for most small hydrocarbons the direct oxidation (in presence of humid O2) is not selective. The main reason for the lack of selectivity is the nature of the free radicals which occur during the reaction and the high exothermic behaviour of the reactions which promotes the sub-oxidation. The latter is due to the fact that, under thermal conditions (in the liquid or gaseous phase), the attack of the oxidizing species on the partially oxidized compounds occurs more easily than on the starting hydrocarbon. The lack of control increases as the products accumulate on the surface, thus limiting the conversion to a few percent in most of the processes used.
The main objective of this project is to study the photo-assisted oxidation of methane, using photocatalysts (semiconductors) supported on zeolites. Contrary to the thermal catalysis oxidation of methane at relatively high temperatures (to activate the methane and generate the active species), photocatalysts are able to generate oxidizing active species at lower temperatures (e.g. ambient temperature for example). On the other hand, zeolite can improve the conversion by increasing the contact surface between methane and the photocatalyst surface. The selectivity can be also promoted by the adsorption of the desired product (generally basic) on the acid sites of the zeolite (limiting the total photooxidation).
The candidate should have a thorough knowledge in catalysis/photocatalysis. Knowledge on IR spectroscopy, gas chromatography and / or mass spectrometry will be a plus.
Stage M2 en photocatalyse
Starting date: 01/02/2017 (flexible) for 5 months. Grant≈550€/month
Contact : mohamad.elroz[at]ensicaen.fr