Abstract:

Two γ-Al₂O₃ washcoats on FeCrAl substrate were prepared by dip-coating boehmite sol gel or γ-Al₂O₃ slurry. The effects of coating solution on the washcoat properties were extensively studied. The washcoat morphology, crystal structure, texture and adhesion to substrate were investigated by SEM, XRD, nitrogen physic sorption and ultrasonic vibration. At coating loading less than 3%(mass), boehmite washcoats were crack-free but γ-Al₂O₃ washcoats were crack-rich. At coating loading above 8%(mass), boehmite washcoats developed crack, flake and delamination whereas γ-Al₂O₃ washcoats developed only crackings without delamination. In case of requirement for relatively low coating loading (<8%), boehmite washcoats were more suitable as carrier for monolithic catalysts due to higher specific surface area and pore volume than γ-Al₂O₃ washcoats. γ-Al₂O₃ washcoats were preferred as catalyst carrier if higher coating loading was needed (>8%).

Key words: monolith, catalyst support, sol-gel, slurry, alumina washcoat, adhesion

摘要：

利用浸渍提拉法（dip-coating），分别采用铝溶胶与氧化铝浆液在FeCrAl金属载体上制备了两种γ-Al₂O₃活性涂层，考察了涂覆液种类对涂层性质的影响。利用扫描电镜、X射线衍射、氮气物理吸附和超声波振动方法考察了两种涂层的表观形貌、晶型结构、织构性质及涂层与金属载体之间的结合力。研究结果表明，当涂层负载量小于3%（质量分数，下同）时，溶胶涂层可以避免开裂，而浆液涂层无法避免开裂发生；当负载量大于8%时，溶胶涂层在干燥后会开裂翘起甚至直接脱落，而浆液涂层虽然开裂加剧但是不会直接脱落。对于涂层厚度需求较低的体系（涂层负载量小于8%），溶胶涂层的比表面积和孔容比浆液涂层更大，更适合作为催化剂活性载体；而对于涂层厚度需求较高的体系（涂层负载量大于8%），则应选择浆液涂层。

关键词: 整体器件, 催化剂载体, 溶胶-凝胶, 浆液, 氧化铝涂层, 结合力