(441b) Process Intensification Via Batch-to-Continuous Transition in the Production of Lubricants

Authors: 
Al Azri, N., University of Pittsburgh
Sam-Gyandoh, E., University of Pittsburgh
Mantripragada, H. C., University of Pittsburgh
Clifford, C., University of Pittsburgh
Enick, R. M., University of Pittsburgh
Kowall, C., The Lubrizol Corporation
Veser, G., University of Pittsburgh
Production of large volume specialty chemicals to-date is conducted almost exclusively in large volume batch or semi-batch reactors. Transition to much smaller continuous processing technology offers the prospect of strong improvements over the century-old batch technology in terms of lower unit energy consumption, smaller footprint, less waste generation, increase in process reliability, and more consistent product quality. The present project, a close collaboration between the University of Pittsburgh and Lubrizol Corporation, aims to demonstrate this transition for succinimide dispersant chemistry as a test case to develop a systematic methodology for batch-to-continuous transition via rapid acquisition of reliable reaction kinetics, implementation in accurate reactor models, validation in a continuous tubular reactor, and, ultimately, construction and demonstration at pilot plant scale. In the present contribution, we focus on validation of reaction kinetics derived from batch experiments in a lab-scale continuous reactor, investigation of the major differences between the two processing technologies and highlight some of the key design considerations for the pilot plant continuous reactor.

The production of succinimide dispersants occurs via amination of a poly-isobutylene succinimide anhydride (PIBSA) with a polyamine. The reaction proceeds via a two-step mechanism: An irreversible amination to an amide acid intermediate, followed by a reversible dehydration reaction to produce water and the desired dispersant molecule. A complete family of dispersants is made by varying molecular weight of PIBSA, structure of the polyamines, and stoichiometric ratio of the two reactants. In the batch process, the water that is co-produced with the desired dispersant product is continuously removed from the head space at the relatively high reaction temperatures, rendering the dehydration step effectively irreversible. In contrast, the presence of water in the continuous reactor renders the dehydration step incomplete due to reversibility and identifies water as a key “contaminant” in this reaction system. However, we find that water removal from the product stream in a subsequent evaporation step results in spontaneous decomposition of the amide acid to the desired dispersant product, resulting in quantitative recovery of the desired product which is chemically and physically indistinguishable from the batch product and fulfills commercial specifications. The presentation will present and discuss these findings and their implications for design of an intensified continuous process.