Three step synthesis of benzylacetone and 4-(4-methoxyphenyl)butan-2-one in flow using micropacked bed reactors

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2019-12, Vol.377, p.119976, Article 119976
• Main Authors: Waldron, Conor, Cao, Enhong, Cattaneo, Stefano, Brett, Gemma L., Miedziak, Peter J., Wu, Gaowei, Sankar, Meenakshisundaram, Hutchings, Graham J., Gavriilidis, Asterios
• Format: Article
• Language: English
• Subjects: Cascade synthesis; Catalytic microreactor; Coupling; Hydrogenation; Oxidation; Telescoped synthesis
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2018.09.137

[Display omitted] •Three catalytic reactors and a separator were combined in a telescoped flow system.•Telescoped flow synthesis allowed different operating conditions for each reaction.•Telescoped flow achieved higher yields than batch for production of ketones. The synthesis of benzylacetone from benzyl alcohol and of 4-(4-methoxyphenyl)butan-2-one from 4-methoxybenzyl alcohol, which were previously performed in a batch cascade, were successfully performed in a telescoped flow system consisting of three micropacked bed reactors and a tube-in-tube membrane to remove oxygen. The system consisted of approximately 10 mg of 1 wt% AuPd/TiO2 catalyst for oxidation, 150–250 mg of anatase TiO2 for C–C coupling and 10 mg of 1 wt% Pt/TiO2 for reduction, operating at 115 °C, 130 °C and 120 °C respectively. Oxygen and hydrogen flowrates were 2 and 1.5 NmL/min and alcohol solution inlet flowrates were 10–80 µL/min, while the system operated at a back pressure of 5 barg. This system achieved significantly increased yields of benzylacetone compared to the batch cascade (56% compared to 8%) and slightly increased yields of 4-(4-methoxyphenyl)butan-2-one (48% compared to 41% when using the same catalyst supports). The major advantage of the telescoped flow system was the ability to separate the three reactions, so that each reaction could have its own catalyst and operating conditions, which led to significant process intensification.