超临界浸渍法制备NiO/有序介孔Al2O3纳米复合材料及其光催化性能研究

Preparation of NiO/Ordered Mesoporous Al_2O_3 Nanocomposites via Supercritical Carbon Dioxide Impregnation and their Photocatalytic Properties

以异丙醇铝为铝源、盐酸为催化剂、大分子嵌段共聚物F127为模板剂,通过溶剂挥发法成功合成了有序介孔氧化铝,并以其为载体、六水合硝酸镍为前驱体、甲醇作夹带剂,以超临界二氧化碳作为绿色溶剂,采用超临界浸渍法成功制备了NiO/有序介孔Al_2O_3纳米复合材料,重点考察了浸渍温度、时间和浸渍压力对NiO负载量以及颗粒尺寸的影响。研究表明:相比于等体积浸渍法,超临界浸渍法制备的复合材料的氧化镍颗粒大小均一,分散均匀,且介孔氧化铝的有序性保持完好。紫外光催化降解刚果红溶液实验表明:超临界浸渍法制备的复合材料光催化性能明显优于等体积浸渍法,采用超临界浸渍法制备的催化剂,反应时间为150 min时去除率接近95%,重复使用5次后光催化活性几乎不变且微观形貌基本无变化。

Ordered mesoporous alumina was synthesized using aluminum isopropoxide as the aluminum source, hydrochloric acid as the catalyst and F 127 as the template via a solvent evaporation method, which was then used as the support to prepare NiO/Al2O3 nanocomposites using Ni（NO3）2.6H20 as the precursor and methanol as the co-solvent via supercritical carbon dioxide impregnation. Effects of temperature, pressure of supercritical carbon dioxide and impregnation time on NiO loading and NiO particle size were investigated. The results indicate that compared with incipient wetness impregnation, more uniform NiO nanoparticles are dispersed on/in mesoporous alumina and ordered mesostructure of Al2O3 is well kept via supercritical impregnation. Photodegradation experiments indicate that the nanocomposites prepared by supercritical carbon dioxide impregnation exhibit better photocatalytic activity for congo red degradation under ultraviolet light than those prepared by incipient wetness impregnation. The congo red removal rate is -95% after 150 min, and the photocatalytic activity and microstructure of the nanocomposites are well kept after five cycles.