金属丝网上氧化铝催化剂载体层的水热合成制备工艺

Preparation of alumina catalyst support layer on wire mesh by hydrothermal synthesis

采用水热合成方法,成功地在FeCrAl金属丝网上制备出形貌可控且热稳定性良好的簇状氧化铝涂层。系统地研究了溶剂组分、沉淀剂浓度和溶液体系的pH值等制备工艺参数对涂层形貌的影响,获得了优化的制备工艺,并对涂层进行了热稳定性和结合力测试。结果表明,去离子水在溶剂中的体积比对涂层形貌的影响最大。当去离子水在溶剂中的体积比为0.2时,可以得到良好的簇状氧化铝结构,去离子水的体积比低于或高于0.2均会导致涂层发生严重的团聚。当溶液中沉淀剂浓度为2mol/L时,生成的簇状氧化铝结构完整且在基体表面连续均匀分布。当第二阶段水热过程的溶液为强酸性或碱性时氧化铝短小且不能在基体表面均匀连续生长。采用优化工艺制备得到的簇状氧化铝涂层的热稳定性优良,在1 000℃以上才发生明显的烧结,此时涂层的比表面积仍能保持在75m2/g。800℃以下时,热震和超声振荡共同导致的涂层质量损失率<10%。

A cluster alumina coating with controllable morphology and good thermal stability was prepared on FeCrAl wire mesh by hydrothermal synthesis. The solvent composition, precipitant concentration and pH of the solution were investigated as main influence factors of the coating morphology to optimize the preparation process. The thermal stability and adhesion of the coating were tested by the thermal shock and ultrasonic vibration subsequently. The results show that solvent composition had crucial impact on the coating morphology. A good cluster alumina could be obtained with V (H 2O)∶ V (solvent)=0.2, otherwise serious agglomeration occurred. The alumina coating with a cluster-like structure and a continuous and uniform distribution was formed on the substrate with C (urea)=2 mol/L. Due to the non-weakly acidic condition in the second stage hydrothermal process, short and non-uniform growth of alumina appeared. Meanwhile, the alumina coating had a good performance in thermal stability. The specific surface area could be maintained at 75 m 2/g at 1 000 ℃, although the coating was about to sinter. The mass loss of the coating after special treatment was less than 10% due to thermal shock and ultrasonic vibration below 800 ℃.