Continuous selective hydrogenation of citral in a trickle-bed reactor using ionic liquid modified catalysts

The influence of the ionic liquid [BMIM][N(CN)2] on the palladium catalyzed hydrogenation of citral in a trickle-bed reactor has been investigated. Applying the SCILL concept (solid catalyst with ionic liquid layer), it was possible to attain citronellal selectivities close to 100% at the cost of catalyst activity. However, the yield of this intermediate was approximately four times higher compared to the neat palladium catalyst. The latter and its SCILL counterpart both seem to have long-term stability, which is relevant for any future industrial application. This is the first time that SCILL systems have been compared directly to their IL-free equivalents in continuous mode.

Graphical abstract. The influence of the ionic liquid [BMIM][N(CN)2] on the palladium catalyzed hydrogenation of citral in a trickle-bed reactor has been investigated. Applying the SCILL concept (solid catalyst with ionic liquid layer) it was possible to attain citronellal selectivities close to 100%.Figure optionsDownload full-size imageDownload high-quality image (98 K)Download as PowerPoint slideResearch highlights▶ Citral hydrogenation has been investigated over supported catalysts with an ionic liquid layer (SCILL) of [BMIM][N(CN)2] in continuous mode using a trickle-bed reactor (TBR). ▶ The SCILL catalyst exhibits long-term stability. ▶ Selectivities to citronellal close to 100% at high conversion were obtained.