Metal–Organic Gel Derived N-Doped Granular Carbon: Remarkable Toluene Uptake and Rapid Regeneration

Porous carbon materials with chemical and thermal stability and high porosity have been widely used for volatile organic compound (VOC) purification. Designing granular carbon with remarkable adsorption capacity and rapid regeneration is of great significance for the capture of VOCs from high humidity air. Herein, a series of N-doped granular carbons were synthesized by direct carbonization of metal–organic gel (MOG). The N-doped granular carbons (C700 and C700K) feature high surface area, hierarchical pore, and abundant N,O multifunctional groups. The toluene adsorption capacity of C700K is highly improved (9.0 mmol/g toluene at P/P0 = 0.1) in comparison with MOG (4.81 mmol/g toluene at P/P0 = 0.1). The toluene breakthrough time of C700K is over 4 times longer than that of MOG at wet conditions (60% RH, 298 K), also much longer than that of widely used carbon materials, zeolites, and representative MOFs, including BPL activated carbon, coconut shell activated carbon, carbosieve, ZSM-5, and MIL-101(Cr). Furthermore, the N-doped granular carbons also exhibit excellent hydrophobicity and can be regenerated rapidly. The internal pore channel and desorption kinetics reveal that the effective diffusion length plays a critical role in the regeneration rate.