Interestingly, catalysts containing Cu and Ga are reported
in the literature, too. For instance, Toyir et al. (2001b)found
that CuO/Ga2O3/SiO2 catalysts prepared by impregnation
method were highly selective and stable in the temperature
range, 250–270
◦C. The use of hydrophobic SiO2 enhanced the
activity, selectivity and stability of the catalyst. The modification of properties of Cu particles was attributed to the
presence of very small particles of Ga2O3 on the surface.
Liu et al. (2005)used nano-crystalline ZrO2 as support for
the preparation of CuO/Ga2O3/ZrO2and CuO/B2O3/ZrO2 catalysts. AtT= 250
◦
C,P= 2 MPa and space velocity = 2500 1/h, the
values of methanol yield for the Ga- and B-containing catalysts were 1.93 and 1.8 mmol/(g h), respectively. It was found
that nano-crystalline ZrO2 changes the electronic structure
and affects the metal and support interactions on the catalyst. Consequently, this results in facile reduction, intimate
interaction between Cu and ZrO2, more corner defects and
oxygen vacancies on the surface of the catalyst. The values
of CO2 conversion and methanol selectivity were higher than
those obtained using catalysts prepared by conventional co precipitation technique.
From all the above-mentioned studies, it may be noted that
Cu-based catalysts are promising for methanol production via
CO2 hydrogenation.