How the distribution of reduced vanadium centers affects structure and stability of the MoVOx material. Issue 10 (30th April 2018)

• Record Type: Journal Article
• Authors: Li, Wenqing; Fjermestad, Torstein; Genest, Alexander; Rösch, Notker
• Is Part Of: Catalysis science & technology. Volume 8:Issue 10(2018)
• Page Start: 2654
• Page End: 2660
• Publication Date: 2018-04-30
• Subjects: Catalysis -- Periodicals; 541.395
• DOI: 10.1039/c8cy00402a
• Languages: English
• ISSNs: 2044-4753

Abstract

Abstract : The energy ordering of configurations, with 6 among the 10 V centers reduced, is predicted using 3 easily accessible variables. Abstract : With hybrid density functional theory calculations, we examined how the locations of reduced V sites affects the stability of the bulk MoVO x catalyst material. For 14 exemplary distributions of reduced centers, V 4+, the total energies varied by ∼140 kJ mol −1 per unit cell. Aiming at a conceptual understanding of the stability of this transition metal oxide material, we identified three factors that lead to low-energy configurations: (i) the type of reduced V centers; (ii) the number of notable polaron–polaron interactions, i.e., configurations where two V 4+ centers are separated by a single intermediate Mo center; (iii) the number of pentameric units with a single V 4+ center. Hence, for a more stable material, V centers in the linker units S1 and S3 should first be reduced, followed by a single S7 site per pentameric unit, and, in lower priority, reduced V centers in close proximity should be avoided. Based on this insight, we present a linear relation that predicts the stability of such configurations with a standard error of only 6 kJ mol −1 . Accordingly, the pentameric units of low-energy variants of the MoVO x catalyst material are in a favorable configuration, as proposed for hydrocarbon oxidation.