Novel TPMS carbon-based monolithic catalysts by three-dimensional printing for enhancement of nitrobenzene hydrogenation reaction

Abstract

An additive manufacturing method (digital light procession) is proposed to fabricate carbon-based monolithic catalysts and is applied to nitrobenzene (NB) hydrogenation in a packed-bed micro-reactor. The geometric model of the integrated catalyst is gyroid, a triply periodic minimal surface structure without a dead zone and a large surface area. Compared with particle catalysts, monolithic catalysts have higher porosity and regular pore structure, which can achieve better conversion and selectivity in hydrogenation reactions at high flow rates. The flow characteristics of the monolithic catalyst in the packed-bed micro-reactor were compared between gas–liquid upward and gas–liquid downward flow. It was found that, in the reactor with an inner diameter of 12 mm, the downward gas–liquid process exhibits Taylor flow characteristics, while the upward process for gas–liquid shows bubble flow. Both modes exhibit higher activity in the NB hydrogenation reaction compared with that reported in the literature. Under room temperature and pressure, the gas flow rate was 0.6 mL min⁻¹ and the liquid flow rate was 15 mL min⁻¹, and the gas–liquid downward residence time was 0.83 min. The conversion reached 99% and the selectivity was 98.2%. The three-dimensional printed carbon-based monolithic catalyst has a hierarchical porous structure and a large specific surface area, which can effectively enhance organic hydrogenation reactions.