The higher alcohol synthesis over promoted Cu/ZnO catalysts

Alkali oxides added to methanol catalysts increase the formation of ethanol, n ‐propanol and isobutyl alcohol. This result has been known for many years, yet few quantitative studies have been reported in the literature. Data obtained on a commercial copper‐zinc oxide catalyst promoted with K 2 CO 3 are presented and compared with published work. The optimum promoter concentration was about 0.5% by weight. The H 2 to CO feed ratio was important in determining the higher alcohol selectivity. The rate of production of isobutyl alcohol varied as p p while for methanol, ethanol and n ‐propanol both exponents were positive and less than 1.6. Decreasing the hydrogen to carbon monoxide ratio from 2 to 0.5 more than doubled the isobutyl alcohol selectivity. Chain growth schemes predicting the higher alcohol selectivity are presented and estimates of the parameters are given.