The effect of Cu loading on the formation of methyl formate and C 2-oxygenates from CH 3OH and CO over K- or Cs-promoted Cu-MgO catalysts

Abstract

The reaction of CH 3OH in the presence of CO at 101 kPa over K- or Cs-promoted Cu-MgO is reported. The selectivity to methyl formate was >92 C-atom% whereas selectivity to CO 2 and C 2 species (ethanol and acetic acid) was <8 C-atom% at 498 and 523 K over the promoted 5 wt% Cu-MgO catalyst. The activity increased as the Cu loading was increased from 5 wt% to 40 wt%, whereas at the same conversion, the product distribution was almost the same over both the 0.5 wt% Cs–5 wt% Cu-MgO and the 0.5 wt% Cs–40 wt% Cu-MgO catalysts. At approximately constant specific basicity, an increase in Cu 0 surface area of the promoted Cu-MgO catalysts correlated with an increased methyl formate yield, whereas no correlation between Cu 2+ surface area and methyl formate yield was observed. The results suggest that methyl formate is formed on Cu 0 sites as opposed to Cu 2+ sites. The mechanism of methyl formate formation from CH 3OH over the promoted Cu-MgO catalysts is discussed in view of these results.