| Popis: |
The influence of the preparation method of methanol catalysts composed of copper associated with rare earth oxides (eg Cu-La 2 Zr 2 O 7 and ZnO promoted Cu-La 2 Zr 2 O 7 systems) on the catalytic behaviour is discussed. Good activities and improved aging properties are always associated with a high copper surface area and a reasonnable crystallinity of the La 2 Zr 2 O 7 pyrochlore. For Cu-La 2 Zr 2 O 7 , as well as for Cu-ZnO catalysts, an almost linear correlation can be observed between the methanol yield, the copper surface area and the amount of formates located on the catalyst's surface. A similar correlation cannot be evidenced on ZnO promoted Cu-La 2 Zr 2 O 7 catalysts. The results are discussed and a mechanism for the hydrogenation of CO 2 to methanol is proposed |
