Ethanol steam reforming over Ni/ZSM-5 nanosheet for hydrogen production

Compared to reforming reactions using hydrocarbons, ethanol steam reforming (ESR) is a sustainable alternative for hydrogen (H₂) production since ethanol can be produced sustainably using biomass. This work explores the catalyst design strategies for preparing the Ni supported on ZSM-5 zeolite catalysts to promote ESR. Specifically, two-dimensional ZSM-5 nanosheet and conventional ZSM-5 crystal were used as the catalyst carriers and two synthesis strategies, i.e., in situ encapsulation and wet impregnation method, were employed to prepare the catalysts. Based on the comparative characterization of the catalysts and comparative catalytic assessments, it was found that the combination of the in situ encapsulation synthesis and the ZSM-5 nanosheet carrier was the effective strategy to develop catalysts for promoting H₂ production via ESR due to the improved mass transfer (through the 2-D structure of ZSM-5 nanosheet) and formation of confined small Ni nanoparticles (resulted via the in situ encapsulation synthesis). In addition, the resulting ZSM-5 nanosheet supported Ni catalyst also showed high Ni dispersion and high accessibility to Ni sites by the reactants, being able to improve the activity and stability of catalysts and suppress metal sintering and coking during ESR at high reaction temperatures. Thus, the Ni supported on ZSM-5 nanosheet catalyst prepared by encapsulation showed the stable performance with ∼88% ethanol conversion and ∼65% H₂ yield achieved during a 48-h longevity test at 550 °C.