Hao Huang,Wei Na,Xiangying Wang,Zhenhui Huang,Zhao Ai,Wengui Gao,Hua Wang
A detailed understanding of the role of Y in Cu/ZnO/ZrO 2 catalysts for methanol synthesis was studied by XRD, HRTEM, TPR, TPD, N 2 O titration and XPS techniques in this work. The addition of Y enhances the interaction between Cu and ZnO. With the increase of Y content, the crystal size of Cu and ZnO decreased and Cu 0 surface area increased, CO 2 /H 2 -TPD exhibited the larger CO 2 and H 2 desorption peak at relative high temperature, XPS confirmed the reduction degree of ZnO to Zn 0 on the catalyst surface also increased, and forming more Cu-ZnO x active sites. However, excess Y content leads to a much stronger interaction between Cu and ZnO, which is not beneficial for migration and stabilization of the formed ZnO x species during the reaction atmosphere, and thus generating less Cu-ZnO x sites for methanol synthesis. This work enlightens the migratable and metastabe of the formed ZnO x species on Cu surface by regulation of promoter and offers a perspective for exploring Cu-ZnO interactions in modified Cu/ZnO/ZrO 2 catalysts.
Jilei Lin,Meiqing Shen,Sifeng Bi,Gurong Shen,Feng Gao,Wei Li
Propylene production via propane dehydrogenation (PDH) over supported platinum (Pt) catalysts is a vital industrial process. However, rapid catalyst deactivation due to coking necessitates periodic regeneration under harsh oxidative conditions. While alloying Pt with transition metals significantly reduces coking, these alloy catalysts often exhibit poor regeneration stability. In this study, we demonstrate that supporting PtIn nanoparticles on Y2O3-modified δ-Al2O3 yields a PDH catalyst with significantly improved activity and stability. This catalyst achieves propane conversion rates close to the thermodynamic equilibrium at an ultralow Pt loading of 0.1 wt %, along with high propylene selectivity. Notably, this catalyst also exhibits remarkable regeneration stability. Through reaction-regeneration cycling experiments with various catalyst formulations, we reveal that the alloy effects between Pt and In are primarily responsible for enhanced catalyst stability under steady-state reaction conditions by suppressing coke formation. Meanwhile, the incorporation of Y2O3 as a support component significantly improves stability during regeneration. Density functional theory (DFT) calculations further elucidate the key factors contributing to the enhanced anticoking properties of the catalyst under PDH reaction conditions.
Ultra-high Ni quaternary cathodes (LiNi x Co y Mn z Al 1-x-y-z O 2 , 1 x 0.8) demonstrate superior cycling stability, positioning them as promising Ni-rich cathode candidates for next-generation lithium-ion batteries. However, increasing demand for higher energy density necessitates higher operation potential, which in turn exacerbates intrinsic challenges, such as poor chemical stability and diminished thermal stability. To address these challenges, an yttrium (Y) modification strategy has been carried out to enhance structural and interfacial stability. Compared to pristine, Y-modified samples show enhanced high-potential and high-temperature performances. In detail, it reveals a specific capacity of 228.5 mAh g −1 within an extended potential window of 3.0–4.5 V and retains 90.7% of its capacity after 200 cycles. When operated at an elevated temperature of 55 °C, it also presents a good capacity retention of 80.4%. The role of Y dopant has been systematically investigated using advanced techniques such as density functional theory (DFT) and in-situ experiments. Results indicate that Y primarily substitutes Ni sites, thereby stabilizing the oxygen framework to enhance cycling stability at a higher operation potential or elevated temperature. Moreover, the formation of surface-coated solid electrolyte layers effectively suppresses interfacial side reactions, contributing to improved cyclability under high-potential and high-temperature conditions.
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