喷雾干燥-煅烧制备钨钴氧化物粉末的反应机理

Reaction mechanism of W-Co oxide powders prepared by spray drying-calcination method

以偏钨酸铵（AMT）、醋酸钻Co（CH3COO）2·4H2O、有机碳为原料，通过喷雾干燥得到前驱体粉末，然后在氮气氛下煅烧制备钨钴氧化物复合粉末；并对AMT、醋酸钻及前驱体粉末进行TG-DSC-DTA分析，用XPS对钨钴氧化物粉末进行价态分析，以x射线衍射对钨钴氧化物粉末进行物相分析，用SEM对粉末进行形貌分析。结果表明：煅烧温度550℃、氮气流量6．5m^3／h、煅烧时间20min制备的钨钴氧化物粉末粒度为10～125μm，平均粒度为50μm，产物为裂解碳、WO3、CO3O4。此温度可避免AMT分解生成的WO3在水蒸气作用下生成钨水化物W02（OH）2；避免WO2（OH）2在H2作用下还原成w粉；及避免w粉沉积在早先被还原的w核上使w粉颗粒长大。

Using ammonium metatungstate （AMT）, cobalt acetate （Co（CH3COO）2.4H20） and organic carbon source as raw materials, precursor powder was prepared through spray drying, then was calcined in N2 to prepare W-Co oxide composite powder. TG-DSC-DTA analysis was applied on AMT, cobalt acetate and precursor powder, XPS was used to analyse valence state of W-Co oxide composite powder; XRD was used to analuse phase composition of W-Co oxide composite powder, SEM was used to analyse morphology of the powder. The results show that, the particle size of W-Co oxide powder prepared at 550 ℃ with 6.5m3/h N2 for 20 min is 10-125μm, and average particle size is 50 μm. The products by calcining W-Co oxide are cracking carbon, WO3 and Co3O4. It is at 550 ℃ that WO3 generated by AMT decomposition can be avoided to produce WO2（OH）2 under the effect of water vapor, WO2（OH） 2 can be avoided from reducing to W powder in H2, W powder can be avoided from depositing on W core, which makes W powder particles growing.