CO/H_2在Cu/ZrO_2催化剂表面吸附行为原位红外表征

FT-IR STUDY OF ADSORBED SPECIES OF CO/H_2 AND CO/H_2 OVER Cu/ZrO_2

用原位FT IR法比较了Cu ZrO2 和ZrO2 催化剂表面对CO及CO H2 的吸附行为。结果表明 ,CO在 5 0℃便可以在Cu ZrO2 表面形成b HCOO Zr、Zr COO- 和b HOCOOZr物种 ,吸附温度升高 ,b HOCOOZr逐渐分解生成Zr OH和CO2 ,而b HCOO Zr吸附物种逐渐增强。b HCOO Zr物种在Cu ZrO2 催化剂表面生成速率远远大于ZrO2 催化剂。在Cu ZrO2 催化剂表面 ,所形成的合成甲醇中间物种 (HCOO Zr和CH3O Zr)均和ZrO2 有关 ,意味着CO加氢反应主要在ZrO2 表面进行 ,铜组分主要向ZrO2 提供吸附CO及H2 物种。

CO and CO/H 2 adsorption over the surface of ZrO 2 and Cu/ZrO 2 was investigated by in situ FT IR spec troscopy CO could be adsorbed on the surface of Cu/ZrO 2 to form formate, carboxylate and bicarbonate species at 50?℃ With the rise of adsorption temperature, the formate species became predominant on the surface to Cu/ZrO 2 with the decomposition of bicarbonate The addition of copper in zirconia did not change the surface species on zirconia, but greatly decreased the temperature at which the surface species appeared In addition, the rate of formate hydrogenation on the surface of Cu/ZrO 2 was much faster than that on the surface of ZrO 2 These might be ascribed to spillover of CO and H from copper to zirconia Due to the similarity of the surface species (related zirconium) the surface of zirconia and copper provided adsorbed CO and H species to zirconia active site