采用沉积-沉淀法制备了负载型Au/TiO2催化剂,以甲醛的催化氧化作为目标反应,采用XRD和TEM对该样品进行了表征并考察了金负载量、沉淀剂种类、反应液pH值、沉积沉淀温度、活化气氛、还原温度及时间等对Au/TiO2催化甲醛氧化活性的影响。结果表明:1.80%(质量分数)的Au/TiO2,经过85℃氢气气氛还原。显示了最高的催化甲醛氧化的活性,在30℃、体积空速为15000h^-1 ,甲醛的体积分数为4.5×1014时,可以将50%的甲醛完全转化为H2O和CO2。样品中金物种颗粒平均尺寸为4.5nm。
A series of Au/TiO2 catalysts were prepared by deposition-precipitation (DP) and evaluated using the combustion of formaldehyde at room temperature as a probe reaction. The structures of the catalysts were characterized by XRD and TEM. The effects of varying the preparation conditions including gold loading, precipitant, pH value of the precipitating solution, deposition temperature, activation atmosphere, reduction temperature and time was investigated in detail. The results show that for a volume fraction of 4.5 × 10-4HCHO, a catalyst composed of 1.80% Au/TiO2 activated by H2 at 85 ℃ can oxidize half of the formaldehyde into CO2 and HzO with a gas hourly space velocity (GHSV) of 15000 h-1 at 30 ℃. Transmission electron microscopy (TEM) showed that mean size of the gold particles was 4.5 nm.