论文部分内容阅读
本文用XPS和XRD考察了由Rh_4(CO)_(12)出发制得的Rh/V_2O_5和Rh/TiO_2两种催化剂的金属载体强相互作用的差别。实验结果表明,1)高温H_2还原的Rh/TiO_2催化剂,经氧处理后即能恢复吸H_2能力。Rh/V_2O_5催化剂在较低温度(473K)H_2还原时Rh就进入SMSI状态,吸H_2能力被完全抑制,373K氧处理并不能使之恢复,吸H_2性质表现出不可逆性。2)与Rh/TiO_2催化剂的TiO_2相比,Rt/V_2O_5催化剂的V_2O_5更易还原,Rh对V_2O_5的还原有明显的促进作用。3)担载在TiO_2上的Rh比在V_2O_5上更易还原。4)还原后,催化剂表层的Rh/V、RH/Ti均有较大幅度的降低。用氧空位模型能较好地说明Rh/TiO_2催化剂的实验结果,而Rh/V_2O_5催化剂的实验结果适于用钒氧化物覆盖模型解释。
In this paper, XPS and XRD were used to investigate the difference of the strong interaction between the supported metal catalysts of Rh / V 2 O 5 and Rh / TiO 2 prepared from Rh_4 (CO) _ (12). The experimental results show that 1) Rh / TiO 2 catalyst reduced by high temperature H 2 can recover H 2 adsorption capacity after oxygen treatment. At the lower temperature (473K) H_2 reduction, Rh entered the SMSI state and the ability of H 2 adsorption was completely inhibited. However, the H 2 V 2O 3 was not restored by the treatment of 373K oxygen and the irreversibility of H 2 adsorption was observed. 2) Compared with TiO 2 on Rh / TiO 2 catalyst, V 2 O 5 of Rt / V 2 O 5 catalyst can be more easily reduced, and Rh can obviously promote the reduction of V 2 O 5. 3) Rh supported on TiO_2 is more reducible than V_2O_5. 4) After reduction, the catalyst surface Rh / V, RH / Ti have a more substantial reduction. The oxygen vacancy model can better explain the experimental results of the Rh / TiO 2 catalyst, while the experimental results of the Rh / V 2 O 5 catalyst are suitable to be explained by the vanadium oxide coverage model.