Mixed Zr-Si oxide nanoparticles were investigated to disclose the relation between the Brønsted acidity of these materials and the atomic composition of the particles. To this aim, we combined experimental structural characterizations via X-ray absorption and Solid State Nuclear Magnetic Resonance spectroscopies with Reactive Molecular Dynamics simulations and Quantum Chemistry calculations. Despite the materials’ complexity, we identified the surface hydrogens responsible for the Brønsted acidity by estimating the adsorption energy of pyridine on several topologically distinct hydroxyl groups. Among the investigated sites, the hydrogens connected to the oxygen atoms bridging surface Zr and Si atoms (i.e., Zr-O(H)-Si) exhibited the most marked Brønsted acidity. The agreement of all the employed techniques demonstrates how the proposed concerted characterization effectively elucidates these complex amorphous materials’ structure/properties relationships. These new insights allowed us to develop a material with exceptionally high Brønsted acid character that outperformed benchmark silica-alumina and sulfonated zirconia in the dehydrogenation reaction of 1-octanol to produce olefins.

中文翻译：

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非晶混合 Zr-Si 氧化物纳米颗粒中布朗斯台德酸位的光谱和理论研究

研究了混合 Zr-Si 氧化物纳米颗粒，揭示了这些材料的布朗斯台德酸度与颗粒原子组成之间的关系。为此，我们将通过 X 射线吸收和固态核磁共振波谱进行的实验结构表征与反应分子动力学模拟和量子化学计算相结合。尽管材料很复杂，但我们通过估计吡啶在几个拓扑不同的羟基上的吸附能，确定了导致布朗斯台德酸度的表面氢。在研究的位点中，连接到桥接表面Zr和Si原子的氧原子（即Zr-O(H)-Si）的氢表现出最显着的布朗斯台德酸性。所有采用的技术的一致性证明了所提出的一致表征如何有效地阐明这些复杂的非晶材料的结构/性能关系。这些新见解使我们能够开发出一种具有极高布朗斯台德酸特性的材料，该材料在 1-辛醇脱氢反应生产烯烃中的性能优于基准二氧化硅-氧化铝和磺化氧化锆。