金负载量对低温水煤气变换Au/α-Fe2O3催化剂结构和性能的影响

In this paper, supported Au/α-Fe2O3 catalyst for low-temperature water-gas shift reaction(WGSR) was prepared through co-precipitation method. The reduction procedure was optimized to activate the category of gold catalysts, which involves rhombization of reduction conditions, i.e. reductive gas composition, reduction temperature, and reduction time, using 8.00%Au/α-Fe2O3 catalyst as sample. It was found that the sample, pre-reduced under 150 ℃ for 9 h in reductive gas flow (10% -H2/N2) , exhibits the higher activity. Then the influence of gold loading on the ultimately WGSR activity of Au/α-Fe2O3 catalyst was investigated due to the precious cost of gold, wherein its loading was controlled through adjusting the atomic ratio Au/Fe. The 8.00% Au/α-Fe2O3 catalyst shows the highest activity. The structure of Au/α-Fe2O3 catalysts with different gold loadings were studied by BET, XRD, XRF, UV-VIS, H2-TPR and O2-TPO characterization techniques. The introduction of gold during co-precipitation may suppress catalyst sintering during WGS reaction. During the preparation, the loss of gold will occur; the loss becomes more serious if the designed gold amount is increased. Moreover it will lead to the aggregation of gold particle, which was revealed by XRD and UV-VIS results. The Au/α-Fe2O3 catalysts with optimal Au loading (8.00%) shows the highest activity owing to the present of moderate Au0 particle and theα-Fe2O3 support holding susceptible reduction but resistant to oxidation, revealed by the TPR-TPO results. Therefore, the high catalytic activity of the investigated catalyst was attributed to the synergism between Au0 and Fe3O4.