Synthesis and Physicochemical Characterization of Shaped Catalysts of β and Y Zeolites for Cyclization of Citronellal

Continuous cyclization of citronellal over zeolite-based extrudates was performed in a trickle-bed reactor at 35-70 degrees C and 10 bar of argon. Catalytic results were correlated with the physicochemical properties of the shaped catalyst prepared by extrusion of beta or Y zeolites with binders. Rheological tests were used to elucidate the flow properties of a catalytic slurry and relate them with the extrusion performance. This study revealed that application of methylcellulose and bentonite binder modified the textural and acidic properties of the final extrudates. The main product was (-)-isopulegol at all temperatures with selectivity remaining quite constant with time-on-stream. The results illustrated that a binder such as bentonite cannot be considered inert. The mass-transfer limitations observed in extrudates did not significantly influence selectivity to the desired pulegols. This study also showed that a direct transfer of the batch reactor data to industrial continuous operation in citronellal cyclization is not straightforward.