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CO2 - Loop for Energy storage and conversion to Organic chemistry Processes through advanced catalytic Systems

European Union Seventh Framework Programme
FOCUS ON PHOTOCATALYSTS
 Home Newsletter 3 / July 2014
 

CEOPS EVENTS:

 

 

Workshop
R&D on CO2 utilization in Europe


The CEOPS project held its first workshop on the current status of “R&D on CO2 utilization in Europe” on the 26th of May 2014 in the frame of the EMRS Spring Meeting organized from May 26 to 30 in Lille, France. 

This half day workshop brought together a panel of key actors of the CO2 utilization field in Europe, with keynote speakers capturing the latest developments in this area.
 
This event was open to all participants of the Spring Meeting.

All presentations can be found here.

lille grand palais

 

 


Stay updated for further information on upcoming events!



Next workshop and summerschool will be organized within the frame of the EMRS Spring Meeting 2015 in Lille from May 11 to 15.
 

Project coordinator:

Laurent BEDEL
CEA-Grenoble - LITEN-DTBH
38054 Grenoble Cedex 9
France
Tél: 33-4-38-78-57-20
laurent.bedel@cea.fr

 

CEOPS is based on the use of methane as an easy storable and transportable carbon vector (from intermittent sources) using the existing gas natural network. Its objectives are focused on the development of advanced catalysts and processes for the conversion of CO2 to methane (pathway A), at the point of CO2 emission, and, after methane transportation, the direct conversion of methane to methanol (pathway B) at the final user.

The pathway B focuses on the direct conversion of methane to methanol, alternatively by DBD plasma catalysis or by photocatalysis.

In the photocatalytic path, electron and hole pairs are generated when a semiconductor material is irradiated with light of suitable energy. The transfer of photogenerated carriers to species in the surface makes some redox reactions to take place. In this sense, in the photoxidation of methane to methanol the photogenerated holes would be able to react with water. It gives rise to the formation of hydroxyl radicals (•OH) which could oxidise methane into methanol.

This approximation has been implemented and evaluated in a photocatalytic reactor at IREC, and advanced catalysts were supplied by IREC and IST partners.  

NL3 image intro

 

Experimental set-up

The photocatalytic oxidation of methane tests were performed in a photochemical reactor of 500 mL volume, equipped with gas inlet and outlet. A medium pressure mercury lamp inside the reactor was used to provide UVC-visible light irradiation. The temperature of the reaction was maintained at 55 ºC by a flow of cooling water during the experiment.  A certain amount of the photocatalyst was suspended in 300 mL of water under magnetical stirring. A 20% CH4/He mixture was sparged continuously through the reactor. Prior to irradiation, the suspension was magnetically stirred in the dark for 30 min. After that, the lamp was turned on and gas samples were periodically analyzed by gas chromatography equipped with FID and TCD detectors.

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Photocatalysts

Previous studies indicate that the tungsten oxide (WO3), mainly due to its moderate oxidizing power, is one of the most suitable materials to carry out the photocatalytic oxidation of methane to methanol. Within CEOPS, IREC has developed ordered mesoporous WO3 with a high surface area. In the same way, bismuth-based materials such as BiVO4 (IREC) exhibit interesting properties for this photocatalytic process. On the other hand, alternative catalysts as Zeolites (supplied by IST) have shown a high photoactivity when modified with additives to modify surface acidity.

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Results

- Ordered mesoporous WOexhibits a high surface area (151 m2 g-1) and porous structure. These peculiar properties favor the adsorption of reactant molecules which increase the photocatalytic performance.

- WO3 and IST-4 zeolite show the highest conversions of methane to organic products. BiVO4 displayed the highest selectivity to methanol (~48%). These results indicate that there is a relation between conversion and selectivity for this process. Therefore, highly photoactive catalysts tend to totally oxidize methane, resulting in a decrease of the selectivity to methanol.  

- The higher selectivity obtained with BiVO4 can be explained from some of the properties of this material. Because of its electronic configuration, this material may have a mild oxidising power in comparison to other photocatalysts and thus form lesser amounts of CO2.

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References

K. Villa, S. Murcia, T. Andreu, J.R. Morante. Mesoporous WO3 photocatalyst for the partial oxidation of methane to methanol using electron scavengers. Applied Catalysis B:  Environmental. Accepted. DOI: 10.1016/j.apcatb.2014.07.055

S. Murcia, K. Villa, T. Andreu, J.R. Morante. On the partial oxidation of methane to methanol using bismuth-based photocatalysts. ACS Catalysis. Accepted. DOI: 10.1021/cs500821r