φ-pH diagrams and kinetics of V2O3 prepared by solution-phase hydrogen reduction

作者：Hu, Yi-bo; Zhang, Yi-min^*; Xue, Nan-nan; Hu, Peng-cheng; Zhang, Liu-hong

来源：TRANSACTIONS OF NONFERROUS METALS SOCIETY OF CHINA, 2022, 32(4): 1290-1300.

DOI：10.1016/S1003-6326(22)65874-6

• V2O3
• solution-phase hydrogen reduction
• phi-pH diagram
• kinetics

Solution-phase hydrogen reduction (SpHR) was introduced into V2O3 preparation to overcome disadvantages of traditional reduction roasting, which include a long process, high energy consumption, and generation of pollution. The research mainly focuses on phi-pH diagrams and kinetics of SpHR. Thermodynamic analysis of phi-pH diagrams for the V-H2O system demonstrates that V2O3 preparation via SpHR requires a high temperature, a high vanadium concentration, and sufficient hydrogen in acidic solution. Kinetic analyses show that the activation energy of V2O3 preparation via SpHR is 38.0679 kJ/mol, indicating that the reduction is controlled by a combination of interfacial chemical reaction and internal diffusion. Effects of H-2 partial pressure (slope K=0.05246) on the reaction rate is not as significant as the vanadium concentration (K=1.58872). V2O3 crystals with a purity of 99.59% and a vanadium precipitation rate of 99.83% were obtained under the following conditions: pH=5-6, c(V2O5)=0.5 mol/L, p(H-2)=4 MPa, m(PdCl2)=10 mg, T=250 degrees C, and t=2.5 h.