Combustion synthesis and stability of nanocrystalline La2O3 via ethanolamine-nitrate process

Pure nanocrystalline La2O3 powders were successfully prepared by the combustion method.The effect of ethanolamine-to-nitrate ratio on phase composition and crystallite size of the combustion products was systematically investigated.Pure hexagonal La2O3 powders were almost formed in stoichiometric reaction(ψ=1.15),while metallic La phase was obtained in fuel-rich conditions(ψ≥3.0).The as-synthesized hexagonal La2O3 was found to be chemically unstable in ambient air since a complete transformation to hexagonal La(OH)3 was detected after 24 h exposure to air.The resulting hexagonal La(OH)3 showed an excellent ability to remove water pollutant and could nearly remove 100% of the Congo red at room temperature with a removal capacity of 143.5 mg Congo red/g.The phosphate adsorption data on hexagonal La(OH)3 agreed well with the Langmuir model with the estimated maximum adsorption capacity of 57.8 mg/g.     

pH值对溶液燃烧法制备纳米LaFeO3的影响

以硝酸镧和硝酸铁为氧化剂,柠檬酸为燃料,采用溶液燃烧法制备了钙钛矿型LaFeO3.通过XRD和SEM研究了分别以氨水和NaOH溶液为pH调节剂,前驱物溶液pH值对制备的纳米LaFe03粉体的晶相组成和微观形貌的影响.结果表明不同的pH调节剂和前驱物溶液pH值对燃烧产物的晶相组成、晶粒大小和微观相貌都有显著的影响.氨水调...     

功能化离子液体催化合成辛酸苄酯

以苯甲醇与正辛酸为原料合成了辛酸苄酯,咪唑类和吡啶类具有PS(丙烷磺酸基)功能基团的离子液体作催化剂,考察了其阴、阳离子对催化活性的影响。并选择[PSPy]HSO4为催化剂,研究了酸醇摩尔比、催化剂用量、反应温度和反应时间等对酯化率的影响,实验结果表明,催化剂用量为正辛醇的20%(摩尔分数),反应温度120℃,反应时间2.5h,酯化率达95.3%;此外,该催化剂重复使用10次后,酯化率达94.2%。