Intensification of carboxylic acid esterification using a solid catalyst in a mesoscale oscillatory baffled reactor platform

摘要

Intensified production of carboxylic acid esters has been investigated using a mesoscale oscillatory baffled reactor (meso-OBR), operated in continuous multi-steady states, dynamic and multi-dimensional modes. This study was performed to investigate the suitability of the reactor for solid-liquid reactions, capacity for quality steady states and rapid process development. A heterogeneously catalysed hexanoic acid esterification with methanol was studied in a meso-OBR packed with Amberlyst (TM) 70 resin as an acid catalyst. The esterification conditions investigated were feed molar ratios in the range of 1.5:1-30:1 and residence times in the range of 1 min-20 min. The meso-OBR was operated at oscillatory conditions of 4.5 Hz frequency and 8 mm amplitude (centre-to-peak) and reaction temperature of 60 degrees C. Clear steady states were achieved at all the residence times used, with maximum hexanoic acid to methyl hexanoate conversion of 95.4 +/- 1.0% obtained at 20 min residence time and 30:1 methanol to acid molar ratio. Methyl ester conversions were 98.5 +/- 1.5% at 20 min residence time and 30:1 methanol to acid molar ratio for dynamic screening, and 98.2 +/- 1.1% at 14 min residence time and 21:1 methanol to acid molar ratio for the multi-dimensional mode. Use of dynamic screening required 16% less time and reactant compared to the multi-steady states approach. A more significant reduction in the process development time and reactants requirement, approximately 30% compared to the multi-steady states approach, was achieved using the multi-dimensional approach. This demonstrates a substantial reduction in process development time, another major advantage of the meso-OBR platform as the choice reactor in process development for multiphase reactions. The Amberlyst (TM) 70 entirely regained its catalytic activity after water spiking, and was not permanently deactivated by water. (C) 2017 Elsevier B.V. All rights reserved.