Fast and Highly Selective Continuous Flow Catalytic Hydrogenation of a Cafestol Kahweol Mixture Obtained from Green Coffee Beans
This work investigates batch and continuous flow heterogeneous catalytic hydrogenation of a mixture of cafestol and kahweol (C&K) to obtain pure cafestol. These diterpenes were extracted from green coffee beans, and hydrogenation was performed using well established palladium catalysts (Pd/C, Pd/CaCO3, Pd/BaSO4, and Pd/Al2O3) and a carbon black supported Pd catalyst coated by a covalently tethered SiO2 shell with mesoporous texture (Pd/CB@SiO2) all partially deactivated with quinoline. Pd/C 10% poisoned with 1 wt quinoline gave the best result for batch reaction, producing cafestol from kahweol with high selectivity >99% after 10 min. Excellent selectivity was also obtained with the catalyst Pd/CB@SiO2 with only 1% Pd. In addition, Pd/C quinoline adapted for continuous flow experiments exhibited the best catalytic activity, also providing cafestol with excellent selectivity >99% after 9.8 s.
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