表面含氧基团对AuCl3-CuCl2/C双组分非汞催化剂催化性能的影响

采用HNO₃氧化及在He气氛围经不同温度焙烧处理椰壳活性炭, 以此活性炭为载体, 通过浸渍法制得AuCl₃-CuCl₂/C双组分非汞催化剂, 并用于乙炔氢氯化反应评价. 结果表明, 分别以HNO₃处理、 未处理和400 ℃焙烧处理活性炭为载体的催化剂乙炔转化率最高分别可达98%, 96%和90%; 而以700和1000 ℃焙烧的活性炭为载体的催化剂反应4 h后乙炔转化率急剧下降为30%. 考察了活性炭表面的含氧基团(尤其是羟基)对Au基催化剂的催化性能的影响.

Effect of Surface Oxygen Groups on the Two-component Non-mercury AuCl3-CuCl2/C Catalyst†

The coconut shell activated carbon was oxidized by HNO₃ and calcined at different temperature in the atmosphere of He. It demonstrated that the physical properties of the activated carbons were basically identical before and after different treatments. However, the content of surface oxygen groups, such as phenol and carboxylic, were increased after oxidizing by HNO₃ and decreased in the order of carboxyl, phenol and carbonyl after calcing in different temperatures. Taking the above activated carbons as the carrier, two-component catalysts of AuCl₃-CuCl₂ were prepared by impregnation method. And the catalysts were evaluated by the acetylene hydrochlorination. The results showed that the acetylene conversion rates of the catalysts, which were prepared with the carrier of original activated carbon, pre-treated by HNO₃ oxidation and calcined in 400 ℃ for 1 h, could reach above 96%, 98%and 90%, respectively. And they had good reaction stability in 10 h. The acetylene conversion rates dropped sharply to around 30% after 4 h for the AuCl₃-CuCl₂/He700-C and AuCl₃-CuCl₂/He1000-C catalysts, whose carriers were calcined in 700 and 1000 ℃. The analysis results by BET, H₂-TPR and SEM show that the BET specific surface area decreases mostly, carbon deposition is more serious and active component dispersion is poorer. It prove that the surface oxygen groups, especially for the hydroxyl group, plays an important role in promoting the dispersion of Au, enhancing the stability and reducing the carbon deposition.