Catalytic effect of lithium titanate oxide doped with praseodymium on thermal decomposition of ammonium nitrate
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Catalytic effect of lithium titanate oxide doped with praseodymium on thermal decomposition of ammonium nitrate Alireza Miri1 · Ahmad Tavasoli1 · Mohammad Reza Sovizi2 Received: 5 February 2020 / Accepted: 12 September 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract In this work, lithium titanate oxide (Li4Ti5O12) (LTO) and praseodymium ion doped in lithium titanate oxide (Pr-LTO) were synthesized in a sol–gel simple method, and their catalytic effects on thermal decomposition of ammonium nitrate were reported using thermogravimetric analysis–differential scanning calorimetry (TGA–DSC) techniques. The X-ray powder diffraction, Brunauer–Emmett–Teller surface area measurements, particle size analysis, energy-dispersive X-ray spectroscopy, and scanning electron microscopy techniques were used to identify the structural properties and morphology of LTO and Prdoped LTO. By doping the praseodymium ion within the LTO spinel structure, the surface area increases (from 204.2 m2 g−1 for LTO semiconductor to 318.9 m2 g−1 for Pr-doped LTO), and the catalytic activity improved. The catalytic effects of LTO and Pr-LTO on the thermal behavior of AN were studied via TG-DSC techniques. The thermal decomposition of pure AN (196–400 °C) shifted to lower temperatures, 154–280 °C, and 131–241 °C, in the presence of LTO and Pr-LTO, respectively. The results showed that the catalytic effects of LTO were improved by praseodymium doping. The Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), Starink, and Tang methods were used to determine activation energies of all AN samples at different conversion values (α). The activation energies of pure AN values were 166 ± 3, 166 ± 2, 166 ± 2, and 162 ± 2 kJ mol−1, while AN/LTO activation energies were 145 ± 2, 144 ± 1, 144 ± 1, and 144 ± 2 kJ mol−1 and finally, those of AN/Pr-LTO were 112 ± 1, 109 ± 2, 110 ± 1, and 110 ± 1 kJ mol−1 using FWO, KAS, Starink, and Tang methods, respectively. Keywords Ammonium nitrate · Lithium titanate oxide · Kinetics · Activation energy
Introduction Ammonium nitrate (AN) has numerous applications (e.g., fertilizers and explosive materials) as an excellent source of nitrogen and for mixing with fuel oil as ammonium nitrate fuel oil (ANFO) [1] and as an extracting agent for major element recovery [2]. AN is known as a strong oxidizing under elevated conditions including high temperatures and presence of impurities [1, 3]. It is also employed as an oxidizer agent in composite solid propellants (CSPs) [4] and emulsion explosives [5]. The properties of AN-based composite * Ahmad Tavasoli [email protected] * Mohammad Reza Sovizi [email protected] 1
College of Science, School of Chemistry, University of Tehran, Tehran, Iran
Faculty of Chemistry and Chemical Engineering, Maleke Ashtar University of Technology, Tehran, Iran
2
propellants such as long burn time, slow burn rate, no burn on its self, low burn temperature, and relatively low sensitivity to friction and impact have attracted the attention of researchers in recent years [6, 7]. Also,
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