Anatase–brookite mixed phase nano TiO₂ catalyzed homolytic decomposition of ammonium nitrate

• Published in: Journal of hazardous materials 2011-09, Vol.192 (3), p.1314-1320
• Main Authors: Vargeese, Anuj A, Muralidharan, Krishnamurthi
• Format: Article
• Language: English
• Subjects: activation energy; ammonia; ammonium nitrate; Ammonium nitrates; burning; Catalysis; catalysts; catalytic activity; Combustion; Decomposition reactions; Environmental Monitoring - methods; gases; Inhibitors; Kinetics; Microscopy, Electron, Transmission - methods; Models, Statistical; nanoparticles; Nanostructure; Nanostructures - chemistry; Nanotechnology - methods; Nitrates - analysis; oxidants; Oxidizers; phase transition; Propellants; Surface Properties; Temperature; Thermogravimetry - methods; Titanium - analysis; Titanium - chemistry; Titanium dioxide; water; X-Ray Diffraction
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2011.06.036

Compared to the conventional ammonium perchlorate based solid rocket propellants, burning of ammonium nitrate (AN) based propellants produce environmentally innocuous combustion gases. Application of AN as propellant oxidizer is restricted due to low reactivity and low energetics besides its near room temperature polymorphic phase transition. In the present study, anatase–brookite mixed phase TiO₂ nanoparticles (∼10nm) are synthesized and used as catalyst to enhance the reactivity of the environmental friendly propellant oxidizer ammonium nitrate. The activation energy required for the decomposition reactions, computed by differential and non-linear integral isoconversional methods are used to establish the catalytic activity. Presumably, the removal of NH₃ and H₂O, known inhibitors of ammonium nitrate decomposition reaction, due to the surface reactions on active surface of TiO₂ changes the decomposition pathway and thereby the reactivity.