The hydrogenation of isophorone to trimethyl cyclohexanone using the downflow single capillary reactor

Despite many innovations in the intensification of catalytic multiphase reactors for the small and medium scale manufacture of chemicals, there have as yet been relatively few commercial successes. One reason for this might be that many of these developments inherently incorporate a fixed catalyst, which may not suit an industry that is based on principles of batch manufacture and multi-product plant. This study evaluates an intensified reactor that encompasses the opportunities demonstrated from structured flows and thin channels, together with a mobile, slurry catalyst, namely a capillary reactor with gas/liquid/suspended catalyst flow. A downflow single capillary reactor (SCR) was designed, built and evaluated for the selective hydrogenation of isophorone to trimethyl cyclohexanone using commercial Pd- and Rh-based catalysts. Using the single capillary arrangement, the reaction was shown to be operating under kinetic control. Comparison of the rate of hydrogenation with autoclave showed a significant increase of the reaction rate when capillary reactor was used. The temperature of reaction is a crucial factor in tuning the reaction towards different products. The constant relative reaction rate obtained for different catalyst loading as well as the calculated value of the apparent activation energy show that the reaction of hydrogenation of isophorone is not mass transfer limited in the single capillary reactor.