Isothermal kinetics of reduction and carburization of WO3–NiO nanocomposite powder by CO/CO2

Valendar, Hurieh Mohammadzadeh; Yu, Dawei; Barati, Mansoor; Rezaie, Hamid Reza

doi:10.1007/s10973-016-5883-y

Cited by 5 publications

(1 citation statement)

References 29 publications

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“…The reduction kinetics of tungsten (VI) [20] and nickel (II) oxides [21] by non-metallic reducing agents has garnered interest due to its practical importance. The isothermal reduction and carburization of tungsten and nickel oxides and nickel tungstate over H 2 [22][23][24], CO [25], CO/CO 2 mixture [26] and carbon [27] have been previously reported. In [28,29], the mechanism and kinetics of the reduction of separate oxides of nickel and tungsten were explored by DTA/TG method at 2.5-20 • C min −1 heating rate region.…”

Section: Introductionmentioning

confidence: 88%

Joint Reduction of NiO/WO3 Pair and NiWO4 by Mg + C Combined Reducer at High Heating Rates

Zakaryan

Nazaretyan

Aydinyan

et al. 2021

Metals

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Functional features of Ni-W composite materials combined with successful performance enabled a breakthrough in their broad application. To disclose the formation pathway of Ni-W composite materials at extreme conditions of combustion synthesis in the NiO-WO3-Mg-C and NiWO4-Mg-C systems for the optimization of the synthesis procedure, the process was modeled under programmed linear heating conditions by thermal analysis methods. The reduction kinetics of tungsten and nickel oxides mixture and nickel tungstate by Mg + C combined reducer at non-isothermal conditions was studied at high heating rates (100–1200 °C min−1) by high-speed temperature scanner techniques. It was shown that when moving from low heating to high heating rates, the mechanism of both the magnesiothermic and magnesio-carbothermic reductions of the initial mixtures changes; that is, the transition from a solid-solid scheme to a solid-liquid scheme is observed. The strong influence of the heating rate on the reduction degree and kinetic parameters of the systems under study was affirmed. The simultaneous utilization of magnesium and carbon as reducers allowed the lowering of the starting and maximum temperatures of reduction processes, as evidenced by the synergetic effect at the utilization of a combined reducer. The effective values of activation energy (Ea) for the reactions proceeding in the mixtures NiO + WO3 + 4Mg, NiO + WO3 + 2.5Mg + 1.5C, NiWO4 + 4Mg and NiWO4 + 2Mg + 2C were estimated by Kissinger isoconversional method and were 146 ± 10, 141 ± 10, 216 ± 15 and 148 ± 15 kJ mol−1, respectively.

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