Increase the catalytic activity of metal-organic frameworks by synthesis modulator approach

• Main Author: Zhang, Nian
• Other Authors: School of Materials Science and Engineering
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/55721
• Institution: Nanyang Technological University

Permanently microporous metal-organic frameworks (MOFs), a group of crystalline organic-inorganic hybrid compounds formed by organic linker and metal ions or clusters coordination, have great potential for catalysis applications due to the diverse structure and properties. The applications can be improved further by incorporation various functional components (for instance, platinum (Pt) metal nanoparticles). After study and investigation done in this area on a specific case for the zirconium terephthalate UiO-66 (Zr), it is found that modulation can be used as an approach to increase the catalytic activity of UiO-66(Zr) significantly. With partial substitution of terephthalates by trifluoroacetate, using trifluoroacetic acid (TFA) and acetic acid together during the synthesis can result in a highly ordered crystalline structure. Aiming for obtaining a more open framework with more open sites, thermal treatment of the material is employed. Besides dehydroxylation of the inorganic Zr cluster, it also leads to post-synthetic removal of the trifluoroacetate groups. Here, the challenge was overcome by the incorporation of Pt nanoparticles and TFA which is aiming to create more active sites inside the MOFs without aggregation of Pt nanoparticles on the surfaces of framework. With the demonstration of the catalytic activity of UiO-66(Zr) for a series of reactions can be improved by adding TFA, it is observed that trifluoroacetate groups would replace part of the terephthalate linkers in the MOF structure synthesized, resulting in a more open structured with extra Lewis acid sites material. In addition, incorporation of Pt nanoparticles can further enhance the catalytic activity of the material as proven by the higher conversion during the experiment. Consequently, the material is a great canditate for several Lewis acid catalyzed reactions as highly active catalyst.