Thermodynamic insights into dry reforming of methane over Ni-alloy/Al2O3 hollow fibers via gas adsorption calorimetry

Dry reforming of methane (DRM) offers a promising route for syngas production while mitigating two greenhouse gases (CH 4 and CO 2 ). However, the surface thermodynamics of reactant adsorption remain elusive due to the lack of quantitative tools. Herein, we synthesize self-supporting hollow Al 2 O 3 nanofibers decorated with Ni, NiCo, and NiCu alloys via blow spinning, eliminating the need for pelletization. Among these, NiCo/Al 2 O 3 exhibits superior activity (85% CH 4 conversion at 800 °C) and coking resistance (0.84 wt% carbon after 50 h). For the first time, we quantify the adsorption enthalpies of CH 4 , CO 2 , and H 2 on these catalysts using gas adsorption calorimetry. Notably, CH 4 —a stable tetrahedral molecule—chemisorbs exothermically on Ni sites at 298 K, with enthalpies of −55.2 (NiCo), −78.2 (NiCu), and −87.5 kJ mol −1 (Ni). A strong structure-enthalpy-activity correlation emerges: overly exothermic adsorption hinders catalytic turnover by stabilizing surface intermediates. This thermodynamic framework provides a lens to rationally design DRM catalysts.