Engineering Tandem Catalysis for Direct CO 2 ‐Enabled N‐Methylaniline Synthesis With a Fixed‐Bed Flow Reaction Process

Abstract

Integrated tandem catalysis within a continuous fixed‐bed reactor represents a promising yet underexplored strategy for process intensification in advanced amine synthesis via CO 2 utilization. Here, we demonstrate the direct conversion of nitrobenzene and CO 2 with H 2 into N‐methylaniline in a continuous fixed‐bed reactor over a CuZnZrO x catalyst, achieving 99% conversion and 95% selectivity with stable operation exceeding 100 h. Mechanistic studies identify Cu‐ZnO interfaces in the form of Cu + ‐O v ‐Zn 2‐δ serve as active sites for CO 2 hydrogenation to key intermediate formaldehyde (CH 2 O*), which couples the CO 2 hydrogenation and methylation of aniline derived from nitrobenzene hydrogenation in kinetics. The tandem configuration provides intrinsic heat‐management benefits, recovering 0.341 kg of steam (1.5 MPa, 201°C) per mole of nitrobenzene—far superior to the methanol consumption characteristic of the conventional three‐step route. This work highlights tandem catalysis as an effective reactor‐level strategy that bridges atomic‐scale active‐site engineering with kinetic synergies, advancing continuous‐flow CO 2 valorization toward higher‐value amines.