Sloczynski et al. (2003)studied the effect of addition of Mg
and Mn promoters on the catalytic activity and adsorptive
properties of CuO/ZnO/ZrO2. A catalyst preparation method
which required decomposition of the citrate complexes of the
metals was used. With the addition of these promoters, Cu
dispersion was enhanced. The surface layers were depleted
of Cu and enriched in Zn and Zr. In effect, the promoters were
preferentially accumulated on the surface of the catalysts.
A correlation between the adsorptive properties and the
catalytic activity was established. An overall factor combining
the catalytic activity and the adsorptive properties favouring
methanol synthesis was considered. It was found that this
factor increases in the order CuZnZr < CuZnZrMg < CuZnZrMn.
Using a successive precipitation technique,Yang et al. (2006)
prepared CuO/ZnO catalyst doped with ZrO2. They found that
the presence of ZrO2 led to higher copper dispersion which
was distinctive from that of CuO/ZnO. The CO2 conversion
(26.4%) and methanol yield (0.22 g/(mL h)) using Zr–CuO/ZnO
atT= 250
◦
C,P= 5 MPa, space velocity = 4000 1/h and H2/CO2=3
(mol/mol) were considerablyhigher than those obtained using
CuO/ZnO (16% and 0.14 g/(mL h)).Jung and Bell (2002)studied
the effect of zirconia phase and copper to zirconia surface
on catalyst activity. The catalysts prepared using m-ZrO2
support were 4.5 times more active than those prepared using
t-ZrO2 support. Due to higher concentrations of the active
intermediates, the rate of methanol synthesis on Cu/m-ZrO2
was higher.Raudaskoski et al. (2007)studied the effect of
ageing time during co-precipitation. It was found that the
prolonged suspension ageing time during the preparation of
CuO/ZnO/ZrO2 is advantageous for catalytic activity. As the
ageing time increased, the sodium content of the catalyst
decreased and finer crystallite structures were formed.