Continuous Flow Hydrogenation of Flavorings and Fragrances Using 3D-Printed Catalytic Static Mixers

A new type of additively manufactured catalytic static mixer, coated with alumina-supported metal catalysts, has been used for the hydrogenation of various model compounds commonly employed in the flavoring and fragrance industries. These heterogeneous catalytic reactions were performed inside an intensified tubular flow reactor housing several catalytic static mixers. In addition to electroplated and cold-sprayed catalyst coatings, which were presented by our group in earlier work, we herein demonstrate a series of alumina-supported metal catalysts for the first time, namely Pd, Pt, Ru, and Ni, supported on alumina and deposited on stainless-steel static mixers. The continuous flow hydrogenation of (−)-isopulegol at 24 bar and 130 °C produced the high value product (−)-menthol at full conversion with a 98.8% purity and a space-time yield of 2.66 kg L–1 h–1.