Exploring the catalytic performance of a series of bimetallic MIL-100(Fe, Ni) MOFs

[EN] A series of mixed-metal Fe-III/Ni-II metal-organic frameworks (MOFs) of the MIL-100 type containing different metal ratios have been synthesized de novo, following an approach that requires tuning of the Fe-III/Ni-II reactivity. The resulting heterometallic MIL-100(Fe, Ni) materials maintain thermal, chemical and structural stability with respect to the parent MIL-100(Fe) MOF as can be deduced from various techniques. The nature and the oxidation state of the accessible metal cations have been evaluated by in situ infrared spectroscopy and extended X-ray absorption fine structure measurements. The obtained mixed-metal MOFs and the parent material have been evaluated as heterogeneous catalysts in a model acid-catalyzed reaction, i.e., the Prins reaction. It is found that the catalytic activity improves by more than one order of magnitude upon incorporation of Ni-II, with a complete selectivity for the formation of nopol. This increase in the catalytic activity upon incorporation of Ni-II correlates with the enhancement in the Lewis acidity of the material as determined by CO adsorption. The heterometallic MOF can be recycled without observation of metal leaching, while maintaining the crystal structure under the reaction conditions.
This work was supported by the European Commission under the Marie Sklodowska-Curie agreement H2020-MSCA-IF-658224. Measurements at the ROCK synchrotron beamline of SOLEIL were supported by a public grant overseen by the French National Research Agency (ANR) as part of the "Investissements d'Avenir" program (reference: ANR10-EQPX45). H. G. thanks financial support by the Spanish Ministry of Science and Innovation (Severo Ochoa and RTI2018-098237-CO21) and Generalitat Valenciana (Prometeo 2017/083). S. N. thanks financial support by the Fundacion Ramon Areces (XVIII Concurso Nacional para la Adjudicacion de Ayudas a la Investigacion en Ciencias de la Vida y de la Materia, 2016) and Ministerio de Ciencia, Innovacion y Universidades CTQ-2018 RTI2018-099482-A-I00 project.