Atomic-Scale Observations Aid Mesoscale Catalyst Design

Two phases of Mo-V-O–based oxides, M1 and M2, are promising catalysts for direct conversion of propane to acrylonitrile and are believed to act synergistically. Researchers engineered the mesoscale structure of M1- and M2-phase oxides to amplify these effects, greatly improving selectivity for propane ammoxidation. This work may result in developing cheaper chemical industrial processes using propane as the feedstock instead of propylene.

Using aberration-corrected scanning transmission electron microscopy (STEM), the investigators made the first observation of the epitaxial interface formation between the M2 phase and Mo₆O₂₁ type units, the key components of the M1 phase (Fig.1a). A self-assembly mechanism was proposed and tested to explain this structure. From that, the researchers tuned the catalyst-synthesis protocol and obtained a novel catalyst with M1/M2 mesoscale intergrowth and improved catalytic performance (Fig. 1b). 

This work not only opens new avenues for improving this important catalyst system via production of the M1/M2 heterostructure, but also provides fundamental insights into the role of the M1 phase in alkane activation. Additionally, it shows that comprehensive atomic-scale structural and chemical characterization by aberration-corrected STEM can lead to understanding and control of the atomic and mesoscale structure in complex catalyst systems.

Q. He, J. Woo, A. Belianinov, V. V. Guliants, and A. Borisevich, “Better Catalysts through Microscopy: Mesoscale M1/M2 Intergrowth in Molybdenum-Vanadium Based Complex Oxide Catalysts for Propane Ammoxidation,” ACS Nano, http://pubs.acs.org/doi/pdf/10.1021/acsnano.5b00271  (2015).

 

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