碳热还原法制取VC、VN和V(C,N)的热力学原理研究

分析了以V2O5和C为原料,用碳热还原法制取VC、VN和V(C,N)的热力学原理。结果表明,钒氧化物的还原是逐级进行的,反应过程伴随着相变。V2O5的碳热还原反应机理有两种,即主要依靠CO/CO2传质的气-固反应和碳和钒氧化物之间固相扩散传质的固-固反应。何种反应机理占主导地位取决于V2O5和C的初始混合态。提高温度有利于钒氧化物的还原及碳氮化。制取VC应在CO或真空气氛下进行,制取VN和V(C,N)应在N2气氛下进行,其中C,N含量取决于温度和N2压力。

STUDY ON THERMODYNAMIC PRINCIPLE OF PREPARATION OF VC、VN AND V(C,N)BY CARBON-HEAT REDUCING

Thermodynamic principle of preparation VC、VN and V(C,N) with V2O5 and C by carbon-heat reducing is analyzed.The results show that synthesizing process includes phase change and the vanadium oxide is reduced gradually.There are two principles for V2O5 reducing by carbothermal method,one reaction depends mainly on CO/CO2 gas-solid transmitted and another reaction depends mainly on the solid-solid reaction between carbon and vanadium oxide,the reacting principle which is primary is depended on original mixed condition between V2O5 and C.It is favorable to reducing process by increasing temperature.The preparation of VC should be done at the condition with CO or vacuum,but the preparation of VN and V(C,N)should be done at the condition with N2,the content of C and N depend mainly on the temperature and the pressure of N2 in the process.