Ethanol to distillate-range molecules using Cu/MgxAlOy catalysts with low Cu loadings

A series of calcined MgAl mixed metal oxide catalysts with low Cu loadings (0.1-1.5 wt%) were tested for ethanol oligomerization to distillate-range molecules. The low Cu loading catalysts (0.1-0.6 wt%) had high selectivity to linear chain C4+ alcohols (49-63% selectivity) and C6+ esters (45-66% of total esters). More specifically, the diesel fuel precursor selectivities were over 75% for low Cu loading catalysts (0.1-0.6 wt%), with a decrease to 49% for a higher Cu loading catalyst (> 1.2 wt% Cu) due to increased ethyl acetate and acetone formation. Alcohol and ester product selectivities follow a Schultz-Flory distribution. Alcohol selectivity was found to vary inversely with BET surface areas of the catalysts, whereas ester selectivity was found to increase with higher base site counts. However, Cu wt% loading was found to have a stronger impact in overall catalyst activity. The catalysts deactivated proportionally to the number of turnovers mainly due to coking, but could be regenerated by calcination.