Higher alcohols from synthesis gas using carbon-supported doped molybdenum-based catalysts

A series of carbon-supported molybdenum-based catalysts was prepared by incipient wetness impregnation. The materials, when promoted with potassium and additionally with cobalt, were screened for the selective production of mixed higher-molecular-weight alcohols from syngas. The effects of the catalyst preparation parameters (Mo precursor, Mo loading, doping levels of K and Co, and calcination) and of the reaction conditions (temperature and space velocity) were studied. The screening procedure consisted of ramping the temperature steadily from 200 to 400 °C and back again. Adding K results in a maximum in the space-time yield (STY) of total alcohols and the ratio of higher alcohols to methanol. Increasing the reaction temperature results in a monotonic increase in the STY of hydrocarbons, a monotonic decrease in the selectivity toward alcohols, and a maximum in the STY of alcohols. Increasing the space velocity increases the STY and selectivity to alcohols while decreasing the STY of hydrocarbons. Increasing the space velocity also decreases the higher-alcohol fraction in the alcohol products.