The research is part of the PhD work of Maria Ronda-Lloret, funded by the Dutch Research Council NWO. The work, led by Dr. Shiju Raveendran of the Catalysis Engineering group, was carried out in collaboration with the University of Alicante, TU Delft and Tata Steel. The results demonstrate that surface defects (in particular vacancies) in MXene make it a better catalyst than bulk TiC and TiO2. The researchers previously showed that modifications on the surface of MXenes can be used to change the selectivity in low-temperature reactions. With the current work, they extend the application of MXenes to high temperature and also show that the surface modifications at high temperature are not always detrimental for the activity of MXenes.
MXenes are a new family of 2D carbides or nitrides that have attracted attention due to their layered structure, tunable surface groups and high electrical conductivity. Here, we report for the first time that Ti2CTx MXene catalyses the selective oxidative dehydrogenation of n-butane to butenes and 1,3-butadiene. This catalyst showed higher intrinsic activity compared to commercial TiC and TiO2 samples in terms of C4 olefin formation rate. We propose that the stabilisation of structural vacancies and the change in composition (from a carbide to a mixed phase oxide) in the MXene causes its higher catalytic activity. These vacancies can lead to a higher concentration of unpaired electrons in the MXene-derived material, enhancing its nucleophilic properties and favouring the production of olefins.
M. Ronda-Lloret, T.K. Slot, N.P. van Leest, B. de Bruin, W.G. Sloof, E. Batyrev, A. Sepúlveda-Escribano, E.V. Ramos-Fernandez, G. Rothenberg, Shiju N Raveendran: The role of vacancies in a Ti2CTx MXene-derived catalyst for Butane Oxidative Dehydrogenation. ChemCatChem, First published: 04 June 2022 DOI: 10.1002/cctc.202200446