Steam reforming of acetic acid over Ni nanoparticle catalysts encapsulated on Al2O3 using cellulose nanofibers (CNFs) as a template: the role of promoter addition

A novel cellulose nanofiber (CNFs)-templated Ni-Al 2 O 3 catalyst was developed to enable efficient steam reforming of bio-oil aqueous-phase components. CNFs derived from sustainable pulp feedstock served as sacrificial structural templates, promoting hierarchical porosity and improving the dispersion of nickel (Ni) nanoparticles (NPs). Optimization of CNFs template addition demonstrated that Ni© 0.2 Al 2 O 3 (0.2 g) achieved complete acetic acid conversion and a 78.3% H 2 yield at 650 °C and 0.1 MPa, surpassing both lower (0.1 g) and higher (0.3 g) CNFs additions. The incorporation of metal oxide promoters (CeO 2 , MgO, ZrO 2 ) into the optimal Ni© 0.2 Al 2 O 3 catalyst further increased H 2 yield: Ni© 0.2 Ce-Al 2 O 3 reached 91.0% due to redox-driven oxygen mobility, Ni© 0.2 Mg-Al 2 O 3 achieved 89.1% as a result of enhanced basicity, and Ni© 0.2 Zr-Al 2 O 3 attained 89.7% owing to strengthened metal-support interactions. The promoted catalysts maintained complete acetic acid conversion during a 24-hour durability test, with significant carbon balance closure, indicating stable catalytic performance. This enhanced durability is attributed to the selective redirection of carbon deposition toward non-poisoning, support-localized C β species (graphitic or filamentous carbon) rather than active-site-blocking C α (amorphous carbon).