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Rational design of novel heterometallic MOFs for their use in heterogeneous catalysis for cascade reactions

Periodic Reporting for period 1 - hetero-MOF (Rational design of novel heterometallic MOFs for their use in heterogeneous catalysis for cascade reactions)

Reporting period: 2015-05-01 to 2017-04-30

Our current industrial society is characterised by an extensive use of technology and mass production. Such a structure uses a tremendous number of industrial processes with large energy consumptions. One of the major challenges in the chemical industry is therefore to reduce processing costs through the development of more efficient catalytic industrial processes. In this context, heterogeneous catalysis plays a crucial role allowing an easy post-reaction separation and recyclability, which is translated in cost effectiveness. In fact, most of the high-temperature industrial processes have room for improvement in terms of effectiveness as well as use several numbers of steps in the process. A major breakthrough to tackle this issue arises from the design of multifunctional solid catalysts, since it is expected that bi/multi-functionalization achieve specific reactions in one single step thus noticeably reducing processing costs.

The present hetero-MOF project proposed mixed-metal Metal-Organic Frameworks (MOFs) as suitable multi-functional structures for their implementation as superior heterogeneous catalysts. The project targets the direct synthesis of bi-metallic MOFs aiming to improve catalytic performances of the homo-metallic analogous. With this purpose, several goals are envisioned: i) The design and synthesis of new multi-metallic MOF structures. ii) The comprehensive physico-chemical characterisation of the hetero-MOFs. iii) The study of MOFs’ catalytic performances in model reactions.
During the project novel bi-metallic structures based on the archetypal MIL-127 (MIL = Material Institut Lavoisier), MIL-88’s and MIL-100 materials have been synthesized. To obtain the homometallic and bi-metallic materials, different routes were explored, mainly using low temperature synthesis and solvothermal reactions.
In parallel to the synthesis, complete structural and textural characterisation of the novel hetero-MOFs was developed. In situ infrared spectroscopy analysis was carried out on specific heterometallic MOFs to gain insights on the nature and the oxidation state of the accessible cations in the framework.
Finally, to validate the catalytic activity of the obtained heterometallic MOFs as compared to their parent homometallic material, we tested them in acid-catalyzed model reactions. It was found that for a certain metal substitution the catalytic activity improves more than one order of magnitude, with a complete selectivity. It is proposed that the insertion of new Lewis acid sites on the structure effectively promotes the formation of highly reactive defects, which could explain these catalytic performances. These heterometallic MOFs can be recycled in the absence of metal leaching, while maintaining the crystal structure in the reaction conditions.
The work developed in this action is clearly contributing to maintain and improve European excellence in this emerging area of heterogeneous catalysis in MOFs.
Along with the advance of the technical aspects of this action, different strategies for communication and public engagement have been considered with special attention to gender dimensions. This project has participated in events dedicated to the general public with the main idea to stimulate interest in research careers, particularly in children.