Evaluation of reactor concepts for the continuous production of fine chemicals using the selective hydrogenation of cinnamaldehyde over palladium catalysts

• Hydrogenation of cinnamaldehyde over Pd catalysts is performed in a pellet string reactor.
• A scale-up concept with multiple parallel packed channels is presented.
• The effect of liquid velocity, gas holdup and hydrogen pressure was studied.
• A comparable selectivity to a batch reactor was achieved in both reactor concepts.
• Results from single PSR experiments can be transferred easily to production scale.

Two reactor concepts based on the pellet string reactor (PSR) were evaluated using the continuous selective hydrogenation of cinnamaldehyde as a model reaction to characterize the suitability for the application in the production of fine chemicals or pharmaceuticals. Reaction studies were carried out in a single PSR and a scale-up concept consisting of 32 parallel channels (MPSR). The impact of liquid velocity, gas holdup and pressure on the conversion and selectivity were investigated for both reactors. It was found that the continuous reactors deliver a comparably high selectivity to a batch reactor when hydrodynamic conditions are chosen adequately to obtain plug flow. The results also indicate a comparable performance for both reactors in terms of reaction rate and selectivity. Thus, the concept seems to present a promising scale-up method based on single-channel experiments.

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