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From batch to continuous processes: a good answer, but what is the question? Part II* – The purification unit operations, specific situations, the complete process perspective



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The switch from batch to continuous process is a major topical question in the fine chemical, pharmaceutical and biopharmaceutical industries. In spite of a genuine interest, as shown by the profusion of recent literature and symposia on the topic, batch remains the widely accepted standard in these industries and the steps taken toward continuous remain somewhat shy. A paradox? Here, we propose a fresh look at the question through the chemist’s eyes but with process engineer glasses. The first part of this article (1) covered general considerations and simple reactor unit operations. In this second part, we investigate more advanced situations including separation unit operations, the heats of reactions and some specificities associated with biochemical synthesis. Finally, the process is approached as a whole, connecting all unit operations together.

*Part 1 was published in Chimica Oggi - Chemistry Today, vol. 34(4) July/August 2016, pp. 38-43.



Despite a genuine interest in switching from batch to continuous operations, relatively few industrial processes are operated continuously in the fine chemical, pharmaceutical and biopharmaceutical industries. On top of historical or even psychological barriers, there are possibly good technical reasons for that.

We have seen in part I that moving from batch to continuous is certainly not a systematic winning lottery ticket, and that, on the contrary, under given circumstances, a continuous stirred reactor can be less productive than a batch stirred reactor.

Using simple illustrations, we have seen that a smart reac