Effect of Si/Zr ratio on the catalytic behavior of Pt-Cu/Zr-SBA-15 in continuous methane dry reforming

Mesostructured SBA-15 supports with varying zirconium contents were synthesized through a single-step
hydrothermal route by systematically adjusting the Si/Zr molar ratio. These Zr-incorporated mesoporous
materials were subsequently employed as hosts for a bimetallic catalytic system, in which 5 wt% copper
served as the primary active phase while platinum (0.5 wt%) acted as a promoter. The active metals were
introduced using the incipient wetness impregnation technique, employing copper nitrate and chloroplatinic
acid as precursors. The structural and surface characteristics of the synthesized supports and catalysts were
systematically explored using powder XRD, BET analysis, NH3-TPD, TPR, HR-SEM, HR-TEM, and TGA.
Catalytic activity was assessed in the dry reforming of methane under atmospheric pressure. Reactions were
conducted with equimolar CH4 and CO2 feeds (1 : 1 ratio) operated under a GHSV of 36 000 mL g−1 h−1,
between 400 and 800 °C. Structural analyses verified the efficient embedding of Zr atoms within the silica
structure. Particularly, samples with Si to Zr ratios of 5 and 10 exhibited enhanced surface acidity while
avoiding the crystallization of ZrO2 (anatase phase). Among the tested formulations, the Pt-Cu/Zr-SBA-15
catalyst possessing a Si to Zr ratio of 5 displayed the most promising performance. It achieved CH4 and CO2
conversion levels of 90% and 95%, respectively, with a favorable H2/CO ratio of 3.8 after six hours of
continuous operation. The catalyst also demonstrated excellent resistance to sintering and minimized coke
accumulation, highlighting its long-term stability. Post-reaction analyses confirmed negligible carbon
deposition on the Zr-modified catalysts. The superior DRM performance was attributed to several synergistic
factors: strong electronic and structural interactions between copper and platinum, fine dispersion of the
active metal species, reinforced metal-support bonding, and an optimal balance between weak and strong
surface acid sites was observed for the catalyst.