Methane dry reforming over Ni/fibrous SBA-15 catalysts: Effects of support morphology (rod-liked F-SBA-15 and dendritic DFSBA-15)

Santa Barbara Amorphous-15 (SBA-15) is a promising molecular sieve material with its highly uniform porosity; nonetheless, its tubular pore channels discouraged mass transfer of reactants during catalysis. Herein, SBA-15 was altered by microemulsion technique to prepare two fibrous SBA-15 with distinct morphologies, viz. rodliked F-SBA-15 and dendritic DFSBA-15. After Ni impregnation, the Ni/fibrous SBA-15 catalysts (Ni/F-SBA-15 and Ni/DFSBA-15) were catalytically evaluated with methane dry reforming (MDR). From characterization, rodshaped F-SBA-15 had outer fibrous layer whereas dendritic DFSBA-15 consisted of a solid core with radially projected fibres. Besides, Ni/F-SBA-15 possessed uneven sized NiO but Ni/DFSBA-15 had uniform NiO dispersion. Characterization also proved that fibrillation and Ni impregnation did not alter the pristine properties of SBA-15. However, the surface attributes of SBA-15 remarkably reduced after fibrillation and Ni impregnation. The strength of metal-support (Ni-SiO2) interaction could be ranked as: Ni/DFSBA-15 > Ni/F-SBA-15 > Ni/SBA15 (previously reported). Both Ni/fibrous SBA-15 catalysts exhibited high proportion of moderate basicity, which favoured the carbon removal via reverse Boudouard reaction. In accordance with endothermicity, the optimal temperature of MDR over both catalysts was 800 degrees C as greater temperature provoked conspicuous CH4 thermal decomposition. For 50 h MDR at 800 degrees C, both catalysts presented superior catalytic activity and stability. With a fully accessible siliceous framework, Ni/DFSBA-15 attained greater reactant conversions (84.05-87.40% X-CH4 and 81.80-85.60% X-CO2 ) than Ni/F-SBA-15 (80.30-85.80% X-CH4 and 76.73-84.10% X-CO2). In overall, Ni/DFSBA-15 was more coke-resistant than Ni/F-SBA-15 by virtue of its fully accessible structure, uniformly dispersed Ni phase, and stronger metal-support interaction.

Automated summary

Two fibrous SBA-15 catalysts prepared by microemulsion technique exhibited excellent performance in methane dry reforming, with Ni/DFSBA-15 showing superior activity, stability, and coke resistance compared to Ni/F-SBA-15. The fully accessible structure, uniform dispersion of Ni phase, and stronger metal-support interaction of Ni/DFSBA-15 contributed to its enhanced catalytic properties.