(1. 武汉科技大学钢铁冶金及资源利用省部共建教育部重点实验室，武汉 430081；
2. 武汉科技大学钢铁冶金新工艺湖北省重点实验室，武汉 430081；
3. 佛山(华南)新材料研究院，佛山 528200)
摘 要: 紫钨(WO2.72)是三氧化钨(WO3)还原制备碳化钨(WC)催化剂的重要中间产物，系统分析WO3至WO2.72的反应行为对后期高效制备优质WC具有重要意义。本文以CO-15%CO2混合气体为还原剂，结合模型拟合法、TG-DTA、XRD、FE-SEM和热力学计算等方法对其还原WO3制备WO2.72的反应机理和动力学进行分析。结果表明：1015~1131 K范围内，WO3与CO-15%CO2混合气体的还原反应主要由两步过程组成，首先WO3被还原为WO2.9，而后WO2.9继续被还原为WO2.72，即WO3→WO2.9→WO2.72，两者相互分开，依次进行。动力学分析结果表明：WO3被还原至WO2.9和WO2.9被还原至WO2.72均由界面化学反应控速，求取的表观活化能分别为142.182 kJ/mol和128.235 kJ/mol；该模型对变温还原动力学的分析同样适用，此时表观活化能为124.638 kJ/mol，与恒温实验所得结果相符。添加一定含量(质量分数)的Nb2O5(0~0.5%)有利于反应速率的提高，然而Nb2O5含量过高(>0.5%)时反应速率反而下降。结合产物形貌演变和物相转变规律，本文得出了CO-15%CO2混合气体还原WO3至WO2.72的可能反应机理。
关键字: WO3；WO2.72；CO-15%CO2混合气体；动力学；反应机理
（1. Key Laboratory for Ferrous Metallurgy and Resources Utilization
of Ministry ofEducation,Wuhan University of Science and Technology, Wuhan
430081, China;
2. Hubei Provincial Key Laboratory for New
Processes of Ironmaking and Steelmaking,WuhanUniversity of Science and
Technology, Wuhan 430081, China;
3. Foshan (South China) Institute for New Materials,
Foshan 528200, China）
Abstract:Purple tungsten oxide (WO2.72) is an important intermediate product during the reduction of WO3 to tungsten carbide (WC) catalysts, and the systematic analysis of the reaction behavior of WO3 to WO2.72 is an essential step for the efficient preparation of high-quality WC. In this work, the reaction mechanism and kinetics of the reduction of WO3 to WO2.72 by CO-15%CO2 mixed gases were analyzed with the adaptation of model fitting, TG-DTA, XRD, FE-SEM and thermodynamic calculations methods. The results show that the reaction of WO3 with CO-15% CO2 mixed gases is consisted of two steps in the temperature range from1015 K to 1131 K: the first step is the reduction of WO3 to WO2.9, and the second step is the reduction of WO2.9 to WO2.72, i.e., WO3→WO2.9→WO2.72, which are proceeded independently. The kinetic analysis results show that the reductions of WO3 to WO2.9 and WO2.9 to WO2.72 are both controlled by the interfacial chemical reactions with the extracted apparent activation energies of 142.182 kJ/mol and 128.235 kJ/mol, respectively. The current model is also suitable to analyze the kinetics of the non-isothermal reaction, and its apparent activation energies is extracted to be 124.638 kJ/mol, which is in good agreement with the isothermal experimental results. Adding a certain content of Nb2O5 (0~0.5%) is beneficial for the increase of the reaction rate, however, the reaction rate will be decreased when the content is beyond the limitation(>0.5%). Combining the phase transition and morphology evolution law of the reaction products during the reaction process, the possible reaction mechanism of the reduction of WO3 to WO2.72 by CO-15%CO2 mixed gases is proposed.
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