制备条件对Au/AC催化分解臭氧性能的影响

研究了活性炭负载的金催化剂(Au/AC)对低浓度臭氧的催化分解性能,考察了前驱体溶液pH值、干燥方式、焙烧温度等制备条件对催化剂活性的影响,以及空速对臭氧分解率的影响。结果表明,在金前驱体溶液pH值为10、经微波辐射干燥、200℃氢气还原制备的催化剂,金颗粒在活性炭表面的分布更加均匀,尺寸更小,具有更高的催化活性。在室温、相对湿度45%和空速72000h-1时,对浓度为50mg/m3臭氧的分解率保持在90%以上(在2400min内)。N2吸附-脱附和XPS表征结果表明,活性炭载金催化剂在催化分解臭氧后,比表面积和孔体积略有下降;Au4f的XPS峰虽稍向高能方向移动,但仍保持催化活性;活性炭表面碳含量显著下降而氧含量大幅增加,说明活性炭上负载的Au在自身催化分解臭氧的同时,还起到了促进臭氧与单质碳反应的作用。

Influence of Preparation Conditions on Catalytic Activity of Au/AC for Ozone Decomposition

The activity of Au catalyst supported by activated carbon (Au/AC) for decomposition of low-level ozone was evaluated. The influence of preparation conditions such as pH value of precursor solution, drying mode and calcining temperature on the catalytic activity was studied, and the ozone removal ratio was tested under different space velocity at ambient temperature. The results show that the procedure of controlling the precursor pH=10, drying catalysts by microwave and being reduced at 200℃ with H2 can improve the dispersion of gold particle, decrease particle sizes and significantly enhance the activity of Au/AC for ozone decomposition. When the catalytic activity test was carried out under the condition of 50 mg/m~3 ozone in air, relative humidity 45%, space velocity 72 000 h~(-1) and ambient temperature, the ozone removal ratio could be maintained above 90% (within 2400 min). The results of N_2 adsorption-desorption and XPS show that, after the reaction with ozone the specific surface area and pore volume of Au/AC decrease slightly; Au/AC remains active although the spectrum peaks of Au4f shift toward higher. Furthermore, the fact that C content decreased notably while O increased, reveals that the Au supported on AC is concerned with the catalytic reaction and can concurrently promote another reaction between ozone and graphitic C.