Ethyleneamine Purification via Extractive Distillation

The reaction process is divided into multiple stages with different catalysts. Stage 1 uses a Ni-based catalyst to selectively produce MEA with high selectivity (90-95%), while stage 2 uses a Cu-based catalyst to convert MEA to EDA. This segmentation allows each stage to be optimized for its specific reaction, minimizing by-product formation while utilizing the high availability of MEG.

The process performs preliminary conversion of MEG to MEA in stage 1 before proceeding to EDA formation in stage 2. This preliminary action with controlled conditions and selective catalysts prevents direct formation of unwanted by-products like diethanolamine and triethanolamine, while still utilizing the abundant MEG raw material.

The separation process uses dynamic pressure swing adsorption with movable beds of adsorbents. The system dynamically switches between adsorption and desorption phases by changing pressure conditions, allowing continuous separation with reduced energy input compared to conventional distillation. This dynamic approach maintains high product purity while significantly lowering energy consumption.

The process replaces conventional thermal distillation (mechanical/thermal system) with pressure swing adsorption (chemical/physical system). This substitution uses adsorption equilibria and pressure changes instead of heat-intensive distillation, achieving the same purification effect with much lower energy consumption.

The catalytic process is segmented into two separate stages, each with its own dedicated catalyst. Stage 1 uses a Ni-based catalyst optimized for MEG to MEA conversion, while stage 2 uses a Cu-based catalyst optimized for MEA to EDA conversion. This segmentation prevents catalyst deactivation by ensuring each catalyst operates under optimal conditions for its specific reaction, extending catalyst life while maintaining high productivity.

MEA acts as an intermediary substance between MEG and EDA. The first catalyst converts MEG to MEA, which then serves as the substrate for the second catalyst to produce EDA. This intermediary approach allows each catalyst to be highly selective and stable for its specific transformation, improving both productivity and catalyst reliability.