Investigation of Deoxidation Process of MoO3 Using Environmental TEM.

Peijie Ma,Kun Zheng,Lihua Wang,Ang Li

doi:10.3390/ma15010056

Peijie Ma, Kun Zheng + Show 2 more

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https://doi.org/10.3390/ma15010056

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Abstract

In situ environmental transmission electron microscope (ETEM) could provide intuitive and solid proof for the local structure and chemical evolution of materials under practical working conditions. In particular, coupled with atmosphere and thermal field, the behavior of nano catalysts could be directly observed during the catalytic reaction. Through the change of lattice structure, it can directly correlate the relationship between the structure, size and properties of materials in the nanoscale, and further directly and accurately, which is of great guiding value for the study of catalysis mechanism and the optimization of catalysts. As an outstanding catalytic material in the application of methane reforming, molybdenum oxide (MoO3)-based materials and its deoxidation process were studied by in situ ETEM method. The corresponding microstructures and components evolution were analyzed by diffraction, high-resolution transmission electron microscopy (HRTEM) and electron energy loss spectrum (EELS) techniques. MoO3 had a good directional deoxidation process accompanied with the process of nanoparticles crushing and regrowth in hydrogen (H2) and thermal field. However, in the absence of H2, the samples would exhibit different structural evolution.

Highlights

Molybdenum (Mo)-based materials are often used as efficient catalysts for various heterogeneous gas-solid catalytic reactions [1,2]
The MoO3 used in this study is the commercially available MoO3 nanoparticles (NPs) with a 50–100 nm diameter dispersed in ethanol solution and cast on a SiNx-based heating chip
For the in situ experiment, the temperature was controlled by a DENs heating system, and the atmosphere was controlled with an environmental transmission electron microscope (ETEM) gas path system

Summary

Introduction

Molybdenum (Mo)-based materials are often used as efficient catalysts for various heterogeneous gas-solid catalytic reactions [1,2]. Molybdenum oxide (MoO3)/ molybdenum carbide (MoC) catalysts are widely used in the chemical industry due to their value in the carbon cycle catalysis [3,4], including methane reforming [5]. MoO3 is the raw material used to produce MoC [7]. The first step of the MoO3 deoxygenation process, both with MoO3/MoC catalysts and during the molybdenum carbide reaction, deserves to be explored in detail [9,10]. MoO3 and MoOx are two-dimensional materials widely used in devices, which is one of the significances of exploring MoO3 deoxidation [12,13]

Results

Discussion

Conclusion