Instituto de Carboquímica
Zaragoza, Spain
Description
Traditionally most chemical reactions to produce fine chemicals are performed in batch operation. This entails concentration and thermal gradients within the reactor leading to poor control of selectivity, intermittent operation with long reaction times and high separation costs. Nowadays, the benefits of performing chemical reactions in continuous using microstructured reactors are widely recognized. The small diffusion lengths of microreactors minimize concentration and temperature gradients leading to better mixing, small reaction times and high control of selectivity. The operation in flow also decreases the reaction times and facilitates the separation of products. All these factors would render the process more energy-efficient and generate less byproducts, thus contributing to sustainability. The heterogeneous catalysts used in conventional batch reactors are usually in the form of slurries. If these powdered catalysts are applied in a micro packed bed, the pressure drop is so high that makes the process uneconomical. Therefore new solutions are explored such as the coating of catalyst on microreactor walls or structured supports inserted inside microreactors. Structured supports coated with catalyst entail low pressure drop and can be fitted within the dimension of microstructured reactors to be used in flow chemistry. The group of “structured materials for catalytic applications” has wide experience in coating macrostructured supports (graphite felts, monoliths, sintered metal fibers) either with hydrothermal carbon or with carbon nanofibers (CNF). To increase the surface area of hydrothermal carbon coating, porosity will be developed in hydrothermal carbon. The creation of high surface area and the adequate porosity will pave the way for its application in flow chemistry. Recently, there is a great interest in developing metal free catalyst due to the scarcity, high cost and environmental impact of some critical metal catalyst. The final objective of this research work is the preparation of metal-free catalyst to be used in chemical reactions for speciality chemicals production. The group has experience in the preparation and characterisation of monoliths coated with Nitrogen doped CNF and also in the preparation of hydrothermal carbon functionalised with sulfonic groups. The prepared doped structured carbons will be tested in flow chemistry in microchemical devices. In particular, the carbon funcionalised with acid sulfonic groups will be tested in esterification reactions and N-doped CNF in selective oxidation of alcohols under mild conditions. The job will consist on the coating of macrostructured supports (carbon felts, monoliths) with carbon materials (hydrothermal carbon, carbon nanotubes). Special emphasis will be put in the control of the porosity, surface chemistry and conductivity of the carbon coating. The porosity will be controlled using templates and by chemical and physical activation. The surface chemistry and conductivity will be tuned via doping with heteroatoms (O,N,B,P,S). The last aim is the preparation of structured metal-free catalysts to enable the application in chemical reactions performed in continuous flow.
Requirements
- PhD or equivalent in Chemistry
- Good level of English
More information and applications
Application Deadline: 01/08/2013
Application e-mail: jegarcia@icb.csic.es
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