Sustainability Improvements through Catalyst Recycling in a Liquid–Liquid Batch and Continuous Phase Transfer Catalyzed Process

Abstract

Phase transfer catalysis (PTC) is a potentially useful approach to processing but often uses environmentally problematic substances that typically end up in waste streams. The sustainability benefits of catalyst recovery from a third liquid layer in a PTC system were investigated for the O-alkylation of 3-phenyl-1-propanol. The system was operated in both the batch and the continuous modes. The formation of a third liquid phase and using it to recover catalyst reduces equipment footprint, product loss through the waste, and VOC emissions and improves energy efficiency compared to the equivalent process designed without the third liquid layer, but at the expense of higher costs, higher E factor, and lower volume efficiency. Overall, continuous phase transfer catalyst recycling is better than the equivalent batch process in volume efficiency, in-process inventory, mass efficiency, E factor, VOC emission, equipment footprint, and operating cost. However, the batch process with batch catalyst recycling is still more cost-effective in capital investment.

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