Lignin-Derived Hierarchical Porous Solid Base for Efficient Glucose Isomerization via In Situ Active Site Generation

Conventional biochar-based solid base catalysts often suffer from cumbersome preparation procedures and pore blockage during the loading of active components. To overcome these limitations, we developed an in situ construction strategy to fabricate hierarchically porous solid-base catalysts via cross-linking and carbonization of alkali lignin. Using alkali lignin as the carbon precursor, a soft-template-assisted cross-linking system enables the simultaneous formation of a hierarchical carbon framework and in situ generation of basic active sites through one-step pyrolysis under alkaline conditions. The physicochemical properties of the catalysts, including specific surface area, pore structure, and surface basicity, are effectively tuned by adjusting the carbonization temperature (600–800 °C). The optimized catalyst, KLPF-800, exhibits a high specific surface area of 309 m2·g−1 and a well-developed hierarchical pore architecture, delivering excellent catalytic performance in aqueous-phase glucose isomerization. A fructose yield of 33.21% is achieved at 120 °C within 20 min. This work provides a feasible strategy for valorizing lignin and designing efficient heterogeneous base catalysts.