Au/ZnO催化剂原位红外及CO氧化性能研究

Study on the Au/ZnO catalysts in situ FTIR and CO oxidation

利用原位IR技术并结合XRD、BET、TG-DTA-DTG等表征手段,研究了Au/ZnO催化剂的焙烧过程结构与组成的变化,在常温干燥和加湿条件下,考察了Au/ZnO催化剂的CO氧化性能.结果表明,载体前驱体的化学组成是Zn5(OH)6(CO3)2,它在150℃左右开始分解,250℃左右强烈分解为ZnO、H2O和CO2,温度高于300℃后,分解接近完全;Au/ZnO催化剂具有较高CO氧化活性和稳定性,在常温条件下可连续反应2 000 h使CO完全氧化.水分促进了催化剂中类碳酸根物种的累积,对Au/ZnO催化剂的CO氧化性能有不利影响.

The structure and the composition of Au/ZnO catalysts calcinated at different temperature was studied by in situ FTIR combining with XRD, BET or TG-DTA-DTG. The CO oxidation was studied at ambient temperature and in the presence of water vapor in the feed. The results indicate that the composition of basic zinc carbonate is Zn5 （OH）6 （CO3）2 ,which begins to decompose at 150℃ ,decomposes into zinc oxide,water and carbon dioxide at about 250℃ and decomposes completely above 300 ℃. Au/ZnO catalysts exhibit excellent CO oxidation activity and stability,the sample can maintain CO complete conversion in 2000 h. Water promotes the accumulation of carbonate-like species and has positive effect on the performance of CO oxidation.