Sarmad Soomro,Zhenkun Sun,Dennis Y. Lu,Zhihao Zhou,Lin Li,Lunbo Duan
Catalyst deactivation due to carbon deposition and sintering poses a significant challenge to the efficient dry reforming of CH 4 and CO 2 into syngas, particularly at high Ni loadings. To tackle this difficulty, ordered mesoporous silicas with varied pore symmetries were employed as supports in this study to synthesize the Ni-based catalysts using hydrothermal treatment. The 10% Ni/MCM-41 catalyst exhibited the highest conversion rates for CO 2 (81%) and CH 4 (77%), with favourable H 2 /CO (0.92) ratios indicating efficient syngas production Higher Ni concentrations increase active sites and catalytic performance, they also increase carbon deposition, reducing catalyst durability. At lower Ni loadings (4% Ni), catalysts with a 3D pore structure showed improved activity and stability, effectively reducing carbon deposition. This study demonstrates that optimized mesopore symmetries and Ni loadings can enhance catalyst efficiency and durability for syngas production.
Yan Gao,Yiwei Zhang,Yuming Zhou,Chao Zhang,Hongxing Zhang,Shuo Zhao,Jiasheng Fang,Mengqiu Huang,Xiaoli Sheng
In this work, we report a feasible approach to synthesize a ternary nanocomposites , Pt/lanthanum doped mesoporous zirconium oxide (Pt/La 2 O 3 -ZrO 2 ), via an effective two-step method. Ordered mesoporous La 2 O 3 -ZrO 2 composites were firstly fabricated with mesoporous silica KIT-6 as a hard template. Subsequently, uniform Pt nanoparticles encapsulated by 4 hydroxyl-terminated poly (amidoamine) (G4-OH PAMAM) dendrimers were deposited on the La 2 O 3 -ZrO 2 composites. The as-prepared samples were characterized by transmission electron microscope (TEM), N 2 adsorption–desorption isotherm analysis, energy dispersion X-ray analysis (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and temperature programmed reduction (H 2 -TPR). The average size of PtDENs was found to be 1.48 nm in diameter. Furthermore, the introduction of La could improve the structure of the supports which was confirmed by XRD and H 2 -TPR analysis. The reduction of p-nitrophenol to p-aminophenol by NaBH 4 was utilized to evaluate the catalytic performances of catalysts. Results indicated that the Pt/La 2 O 3 -ZrO 2 catalyst calcined in nitrogen at 550 °C exhibited the highest catalytic performance and still kept the high catalytic activity even after six cycles. This phenomenon suggests that synergistic effect among Pt-Zr-La could enhance the catalytic efficiency. Finally, reaction mechanism was proposed for the reduction of p-nitrophenol.
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