In Situ Construction of High-Density Mesopores in Monolithic Catalysts with Enhanced Mass Transport for Hydrogen Production from Methanol Steam Reforming

Methanol steam reforming is a promising pathway for distributed hydrogen production, but its practical deployment is hindered by the structure-transport mismatch in conventionally monoliths, which limits accessibility and effective utilization of active sites. Herein, a low-temperature pore-construction strategy was developed to fabricate monolithic catalysts with a high-density mesoporous architecture via the synergistic action of an endogenous pore-forming agent and a sesbania gum-derived scaffold. Controlled carbonate decomposition under calcination (<250 °C) enables the in situ generation of a high-density mesoporous network while preserving the integrity of the monolithic framework. The optimized M(CO₃)_<i>m</i>(OH)_<i>n</i>/Ex-250 monolith achieves >99% methanol conversion at 240 °C with a H₂ production rate of 353.7 mmol/g_cat·h and stable operation over 50 h. Temperature-programmed desorption analyses of CH₃OH and H₂O further suggest that the high-density mesoporous architecture enhances reactant accessibility by providing abundant and readily accessible adsorption sites within the monolith. This work highlights a viable route toward architecturally optimized monolithic catalysts for efficient hydrogen production.