Continuous Emulsion Copolymerization of Acrylonitrile and Butadiene. Simulation Study for Reducing Transients during Changes of Grade

MINARI, R. J.; GUGLIOTTA, L. M.; VEGA, J. R.; MEIRA, G. R.

Industrial & Engineering Chemical Research

American Chemical Society

Año: 2007 vol. 46 p. 7677 - 7683

0888-5885

This article theoretically investigates the reduction of off-specs generated during changes of grade in an emulsion copolymerization of acrylonitrile (A) and butadiene (B) carried out in an industrial train of 8 continuous stirred-tank reactors. The investigated NBR grades exhibit differences in the copolymer composition, molecular weights, and levels of branching. In the Normal plant configuration, all the reagents are fed into the first reactor. In the Improved plant configuration, intermediate additions of A, B, and chain transfer agent (CTA) are admitted along the train for increasing production and reducing chain branching, polydispersity, and compositional drift. Optimal transitions between Normal steady states and between Improved steady states were calculated. They involved changes between 2 typical copolymer grades and the application of “bang-bang” feed profiles onto A, B, and CTA. According to the model, the “bang-bang” strategies reduce the off-specs between 35% and 60% with respect to simultaneous step changes in all of the reagents.