Bofeng Zhang,Yajie Tian,Dali Chen,Ling Li,Guozhu Li,Li Wang,Xiangwen Zhang,Guozhu Liu
Multimetallic nanocatalysts have attracted increasing attention for steam reforming owing to highly exposed active sites, but often suffering from severe sintering. Herein, we design subnanometric Ni-Pt bimetal clusters (ca. 1.7 nm) encapsulated in Silicalite-1 zeolite (2Ni0.5Pt@S-1) through ligand-stabilized method to prevent sintering by fixing the metal into microporous channels. In the steam reforming of n -dodecane test, 2Ni0.5Pt@S-1 gave an excellent activity and stability with a decrease of conversion only 4% at 600°C for 4 hr, which was about a quarter that of 2Ni0.5Pt/S-1 synthesized by co-impregnation method, ascribing to superior sinter-resistance of encapsulation structure. Moreover, 2Ni0.5Pt@S-1 exhibited a higher H 2 selectivity up to 69.9% than that of 2Ni0.5Pt/S-1 (64.4%), owing to suppressed methanation reaction based on subnanometric clusters. Shape-selective steam reforming of n -dodecane and ofm -xylene was also observed, because of m -xylene could hardly diffuse into the zeolite channels due to its bulky molecular size, further preventing potential deactivation by tars in reforming process.
Yanxin Zhang,Xuesi Hong,Yuzhu Shi,Duo Xu,Yueqin Song,Xiaolong Zhou,Jin An Wang
The present study investigated a novel bimetallic Pt-Mo catalyst encapsulated within Silicalite-1 zeolite for propane dehydrogenation (PDH). The catalyst was synthesized via in situ hydrothermal crystallization, followed by direct high-temperature H 2 reduction without conventional calcination, leading to uniform encapsulation of Pt nanoparticles within the zeolite framework and simultaneous removal of the template and organic ligands. PDH performance was evaluated in a continuous-flow fixed-bed microreactor. Comprehensive characterizations (XPS, CO-DRIFTS, NH 3 -TPD, Raman, etc.) reveal that Mo incorporation in 0.4Pt@S-1 catalyst significantly enhances propane conversion while maintaining high propylene selectivity. Moreover, the bimetallic 0.4PtXMo@S-1 catalyst with 0.1 % Mo doping achieved an outstanding performance at 550 °C and a WHSV of 5.49 h −1 (propane conversion: 43 %, propylene selectivity: 97 %, propylene formation rate: 16.27 mol C3H6 ·g Pt -1 ·h −1 ). The prepared catalyst possessed favorable stability and regeneration performance, showing a deactivation rate of only 0.001454 h −1 after four reaction-regeneration cycles. This enhancement is attributed to synergistic effects arising from Mo incorporation, which promotes Pt nanoparticle dispersion, modulates Brønsted /Lewis acidity, and facilitates interfacial electron transfer between Pt and Mo species. These findings highlight the role of Pt-Mo interactions within zeolite frameworks, providing new insights for designing efficient and stable PDH catalysts.
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