N-Doped holey graphene assembled on fibrous aluminum silicate for efficient carbocatalysis in fixed-bed systems

Abstract

A fixed-bed based catalytic system is ideal for a green organic synthesis process, benefitting from the advantages of easy product purification, simple operation, and convenient catalyst recycling. As the key part of the system, catalytic packing materials with high activity, stability and low flow resistance are highly desired. Herein, we prepare a monolithic hybrid fixed-bed catalyst by co-assembling N-doped holey graphene (NHG) and aluminum silicate fibers (ASFs) clusters (NHG–ASFs) via a one-pot hydrothermal approach in the presence of a doping agent (ammonium hydroxide) and an etching agent (hydrogen peroxide). A loose and porous packing structure can be constructed when the hybrid NHG–ASFs assembly is filled into the continuous-flow reactor. Due to the unique properties such as high activity, excellent stability and low flow resistance of the NHG–ASFs carbocatalyst, the resultant catalytic fixed-bed system exhibits an ultrahigh flow rate (240 mL min⁻¹) and excellent durability toward nitroarene reduction reactions. Furthermore, the interaction of reactants and the possible metal-free catalytic mechanism are proposed based on experimental data and theoretical calculations.