(231c) Batch to Continuous Transition of Large Volume Succinimide Dispersants

The specialty chemicals industry to-date is largely operating using decades old technology based on large-volume batch reactors of tens to hundreds of thousands of gallons in capacity. This technology is simple but inefficient given the advances in science and engineering over the years. There is a large opportunity to improve the cost, energy, and atom efficiency of the processes and reduce their environmental footprint. Hence, the industry is currently undergoing a paradigm shift, moving away from traditional manufacturing approaches to intensified, modular, and cleaner processes.

Succinimide dispersants are widely used in the automotive industry—where they form a key component of engine oils—and in the production of emulsifiers for a wide range of applications, including explosives and metalworking. These highly viscous dispersants are formed via a two-step reaction between Poly-isobutylene succinic anhydride (PIBSA) and polymeric amines. They are traditionally produced in large-volume batch reactors (10-50k gal) with long batch times (~6 hours). Previously, we successfully demonstrated the transition to continuous production of succinimide dispersants using an integrated reactor-separator system. However, to-date, the production of the process feeds is still carried out in batch reactors which prevents the overall process from reaping the full benefits of continuous process operation.

The present study is investigating the production of PIBSA from polyisobutylene (PIB) and maleic acid anhydride (MAA). This reaction poses several challenges for continuous processing: i) highly viscous and poorly miscible reactants; ii) slow kinetics at typical operating conditions which result in long reaction times (>10 hours) and hence require operation at high-temperature, high-pressure conditions (T>200C, P>250 PSIG); and iii) undesired side reactions due to the temperature-sensitivity of MAA and its high reactivity with acidic and basic functionalities. In the present work, we aim to address these issues via use of a suitably designed high-pressure, high-temperature continuous reactor system; improving the mixing via emulsification with the reaction product, PIBSA; and mitigating undesired solids formation to improve product yield. Key to these advances are kinetic investigations of PIBSA formation as guide for transitioning to continuous operation in a stirred tank reactor versus a tubular reactor. Overall, this work aims to back-integrate succinimide dispersants manufacturing for a continuous process operation.