THE EFFECTS OF CARBON-DIOXIDE, METHANOL, AND ALKALI PROMOTER CONCENTRATION ON THE HIGHER ALCOHOL SYNTHESIS OVER A CU/ZNO/CR2O3 CATALYST

The behavior of the methanol and higher alcohol (HAS) syntheses as a function of catalyst promoter concentration, C02 feed gas concentration, and methanol feed gas concentration has been investigated over a Cu/ZnO/Cr203 catalyst at 10 MPa and 285-315°C. In the presence of C02 in the feed gas, the methanol and HAS yields are greater for the unpromoted catalyst than the 0.5% K2CO3-promoted catalyst. The methanol and HAS yields also reach a maximum as the C02 concentration increases for both catalysts. In the absence of C02, both the methanol and HAS yields reach a maximum as the K2CO3 promoter concentration increases. The complex behavior results from the ability of these catalysts to incorporate CO, C02, and methanol into higher alcohols, on at least two different types of catalytic sites. It is suggested that C02 participates directly in HAS on copper sites while alkali/copper interfacial sites are involved in converting CO. Higher alcohol production is therefore very sensitive to the feed gas composition and the components and composition of the catalyst. © 1991.