Dehydrogenation of Alcohol Mixtures to Esters and Ketones

Fischer−Tropsch synthesis produces, among other things, complex mixtures of oxygenated compounds, such as primary and secondary alcohols, which are difficult to separate. The dehydrogenation of alcohol fractions in the C 3 and C 4 alcohol boiling ranges was investigated to determine whether the process would be suitable to produce different types of oxygenated compounds (esters and ketones), which could find application as solvents. The reaction was conducted in the presence of a Cu/Zn/Al 2 O 3 catalyst in a pilot-plant-scale reactor in the temperature ranges of 219−278 °C with the propanol-rich feed and 219−300 °C with the butanol-rich feed (and at atmospheric pressure). The reaction products consisted of esters, ketones, and aldehydes (in decreasing order). The ester yield passed through a maximum with increasing temperature, as a result of secondary reactions, whereas the yield of ketones increased continually with temperature. The activity of the catalyst decreased by ∼15% over a period of 92 days. The selectivity of propyl propanoate, which is the main ester produced from the propanol feed mixture, decreased with time, while the yield of the ketones increased slightly.