Morphology‐ and Functionality‐Controlled Performance of Polymer‐Supported Re Catalysts for Continuous‐Flow Production of 4‐aminophenol and 1,2‐phenylenediamine in a 3D‐Printed Packed‐Bed Reactor

ABSTRACT

Producing aromatic amines remains a significant challenge due to substrate toxicity, catalyst deactivation, and transport limitations in heterogeneous systems. In this study, we present the continuous‐flow reduction of 4‐nitrophenol and 2‐nitroaniline to aromatic amines using polymer‐supported rhenium catalysts operated in a 3D‐printed reactor, enabling controlled reactor geometry and reproducible catalyst bed configurations. Interpenetrating styrene‐based polymer matrices with a distinct porous architecture and core–shell characteristics were employed to evaluate the effect of catalyst morphology on reactor performance under flow conditions. Batch experiments revealed that both polymer porosity and functionalization influence apparent catalytic activity, which ranged between 0.049 and 0.68 s ⁻¹ , while continuous‐flow operation exposed differences in catalyst capacity and stability. Breakthrough experiments demonstrated that nonporous matrices favor prolonged operation, whereas a porous architecture enhances utilization rates but accelerates deactivation. Kinetic modeling of the flow‐mode process using a porous catalyst confirmed that the reaction can be described by a pseudo‐first‐order model, yielding an apparent rate constant of 0.058 s ⁻¹ , enabling identification of 19.44 s as the minimum residence time required for complete 4‐nitrophenol conversion. Based on the results, effective continuous 4‐aminophenol production requires balancing transport efficiency with controlled site accessibility, providing design principles for polymer‐supported non‐noble metal catalysts in intensified flow reactors.