The Hydrogen Reduction Behavior of MoO3 Powder

Abstract

The hydrogen reduction behavior of molybdenum oxides was studied using a horizontal-tube reactor. Reduction was carried out in two stages: MoO 3 → MoO 2 and MoO 2 → Mo. In the first stage, a mixed gas composed of 30 vol% H 2 and 70 vol% Ar was selected for the MoO 3 reduction because of its highly exothermic reaction. The temperature ranged from 550 to 600 °C, and the residence time ranged from 30 to 150 min. In the second step, pure H 2 gas was used for the MoO 2 reduction, and the temperature and residence time ranges were 700-750 °C and 30-150 min, respectively. The hydrogen reduction behavior of molybdenum oxides was found to be somewhat different between the two stages. For the first stage, a temperature dependence of the reaction rate was observed, and the best curve fittings were obtained with a surface reaction control mechanism, despite the presence of intermediate oxides under the conditions of this study. Based on this mechanism, the activation energy and pre-exponential were calculated as 85.0 kJ/mol and 9.18 × 10 7 , respectively. In addition, the pore size within a particle increases with the temperature and residence time. In the second stage, a temperature dependence of the reaction rate was also observed; however, the surface reaction control mechanism fit only the early part, which can be ascribed to the degradation of the oxide crystals by a volume change as the MoO 2 → Mo phase transformation proceeded in the later part.

The Self-Reduction during the Thermal Decomposition of an Ammonium Molybdate

“…MoO 3 is easily reduced by either hydrogen or other reducing gas, and several studies have reported morphology changes during the reduction [17][18][19][20][21] As can be seen, as the direct reduction proceeded, more pores and cracks were observed within the internal structures. This aspect is similar to what was observed during the hydrogen reduction of MoO 3 [3].…”

“…Although there is an operating molybdenum mine in Republic of Korea, the self-sufficiency ratio of molybdenum in Republic of Korea remains under 2% [1]. Most molybdenum resources such as sulfides are imported, and therefore, there have been attempts to improve the molybdenum production technologies and processes in Republic of Korea [3].…”

Coupling Ferricyanide/Ferrocyanide Redox Mediated Recycling Spent LiFePO4 with Hydrogen Production

“…However, it does entail high energy consumption. It is important to note that the energy utilization efficiency in the mechanochemical reaction process is relatively low, with only about 25 % of the energy utilized within the reaction system, while the remaining energy is converted into thermal energy [25] . Therefore, it is of utmost importance to develop a sustainable approach for the recycling of spent LFP batteries.…”

“…The recycling of approximately 23 tons of spent LFP batteries can yield one ton of Li, whereas it would require 750 tons or 250 tons of brine or ore, respectively, to obtain the same amount. This considerable disparity in quantities emphasizes the superior efficiency and economic value of Li recovery through the recycling of spent LFP batteries [25–27] . Meanwhile, the relatively low cost of spent LFP batteries further reinforces their potential for efficient recovery through cost‐effective methods [20] .…”

Coupling Ferricyanide/Ferrocyanide Redox Mediated Recycling Spent LiFePO4 with Hydrogen Production

“…The recycling of approximately 23 tons of spent LFP batteries can yield one ton of Li, whereas it would require 750 tons or 250 tons of brine or ore, respectively, to obtain the same amount. This considerable disparity in quantities emphasizes the superior efficiency and economic value of Li recovery through the recycling of spent LFP batteries [25–27] . Meanwhile, the relatively low cost of spent LFP batteries further reinforces their potential for efficient recovery through cost‐effective methods [20] .…”