The effect of Cu loading on the formation of methyl formate and C2-oxygenates from CH3OH and CO over K- or Cs-promoted Cu-MgO catalysts

The reaction of CH3OH 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 CO2 and C2 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 Cu0 surface area of the promoted Cu-MgO catalysts correlated with an increased methyl formate yield, whereas no correlation between Cu2+ surface area and methyl formate yield was observed. The results suggest that methyl formate is formed on Cu0 sites as opposed to Cu2+ sites. The mechanism of methyl formate formation from CH3OH over the promoted Cu-MgO catalysts is discussed in view of these results.

Methyl formate yield over K or Cs-promoted Cu-MgO catalyst with 5 and 40 wt% Cu. Reaction conditions: 101 kPa, feed He/CO/CH3OH = 0.20/0.66/0.14 M, v0 = 84.4 cm3(STP) min−1, W/F = 12.3 × 10−3 min g (cm3(STP))−1, catalyst weight = 0.98 g.Figure optionsDownload high-quality image (65 K)Download as PowerPoint slideHighlights
► The reaction of CH3OH with CO at 101 kPa over K- or Cs–Cu-MgO is reported.
► Methyl formate selectivity was >92 C-atom% at 498 and 523 K over K– or Cs–5 wt% Cu-MgO.
► At approximately constant basicity, methyl formate yield increased with Cu0 surface area.
► The results suggest that methyl formate is formed on Cu0 sites as opposed to Cu2+ sites.