Two DWC Columns
Crystallization
High Purity
p-Phenylenediamine (pPDA) Purification
Based on US20230365489A1, this process integrates two divided-wall distillation columns (DWCs) with a downstream crystallization step. The first DWC provides a pPDA-enriched stream for crystallization, while the second DWC complements the separation train and improves efficiency.
High Purity
Trace isomer control
Trace isomer control
Energy Saving
Fewer units vs. legacy
Fewer units vs. legacy
Scalable
Pilot → commercial
Pilot → commercial
Process Overview
First Divided-Wall Column
Removes o-/m-isomers and impurities while delivering a pPDA-enriched side-draw that feeds directly to crystallization.
Crystallization
Polishes the pPDA-rich cut, removing residual isomers and improving color stability to yield high-grade pPDA.
Second Divided-Wall Column
Acts as a complementary unit to sharpen other separations, reduce energy demand, and optimize overall plant integration.