Facile preparation of Cr₂O₃ nanoparticles and their use as an active catalyst on the thermal decomposition of ammonium perchlorate

ABSTRACT

Cr₂O₃ nanoparticles were prepared by repeated wet mechanical milling technique. Three drying methods, oven drying, vacuum drying, and vacuum freeze-drying were comparatively used to dry Cr₂O₃ nanoparticles. These processes can be easily scaled up to 10-kg quantities. It took only 2–3 h to cut bulk size to nanometer by milling. The obtained Cr₂O₃ nanoparticles are semi-spherical and homogeneous with an average size of 30 nm measured by SEM and TEM and show similar diffraction peak positions to bulk one investigated by XRD. The TG/DSC study indicated that, compared with bulk Cr₂O₃, Cr₂O₃ nanoparticles obtained by oven drying and vacuum drying, the catalytic performance of Cr₂O₃ nanoparticles obtained by vacuum freeze-drying is the best in lowering the peak temperature of high temperature decomposition and the activation energy, while increasing the apparent decomposition heat and the reaction rate constant of ammonium perchlorate (AP) due to their good dispersion and large specific surface area. The possible catalytic mechanism of Cr₂O₃ on the thermal decomposition of AP was proposed by TG-MS analysis. These findings showed that wet mechanical milling technique combined with vacuum freeze-drying technology is suitable for efficient preparation of Cr₂O₃ nanoparticles, which could be a promising additive for accelerating the thermal decomposition of AP.

KEYWORDS:

• Cr₂O₃
• milling
• ammonium perchlorate
• thermal decomposition
• catalysis

Acknowledgments

This work was financially supported by the National Natural Science Foundation of China (Grant Nos. 21805139 and 51606102), the Fundamental Research Funds for the Central Universities (No. 30918011312), Basic Product Innovation Technology Research Project of Explosives, Youth Scientific and Technological Innovation Project (No. QKCZ201713) and Nanjing University of Science and Technology.

Additional information

Funding

This work was supported by the Fundamental Research Funds for the Central Universities [Nos. 30916011315 and 30918011312]; National Natural Science Foundation of China [No. 21805139, No. 51606102]; Youth Scientific and Technological Innovation Project [No. QKCZ201713]; Basic Product Innovation Technology Research Project of Explosives; Nanjing University of Science and Technology.