乙醇在 Ag 促进、二氧化硅或沸石负载的 Ta、Y、Pr 或 La 氧化物催化剂上的级联反应,ACS Catalysis

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乙醇在 Ag 促进、二氧化硅或沸石负载的 Ta、Y、Pr 或 La 氧化物催化剂上的级联反应
ACS Catalysis ( IF 11.3 ) Pub Date : 2023-02-21 , DOI: 10.1021/acscatal.2c06055
Konstantin Mamedov ₁ , Robert J. Davis ₁

Affiliation

在合适的多功能催化剂存在下，乙醇会转化为 1,3-丁二烯。在这项工作中，路易斯酸阳离子 Ta、Y、Pr 和 La 分散在无定形二氧化硅或 β 沸石上，并在与二氧化硅负载的 Ag 纳米粒子物理混合后，在 573 K 下在乙醇生成丁二烯的级联反应中进行了测试。路易斯酸催化剂的特征在于 X 射线荧光、N ₂物理吸附、扫描透射电子显微镜 (STEM)、X 射线衍射和漫反射 (DR) 紫外-可见和 X 射线光电子能谱。高分辨率 STEM 图像证实了二氧化硅载体上的小氧化物簇尺寸。DR 紫外可见光谱的结果表明，沸石负载的 Ta 和 Pr 催化剂相对于其 SiO _{2具有更小的金属氧化物簇尺寸}同行。_{X 射线光电子能谱证实，负载在沸石上的阳离子的氧化态与其负载 SiO 2}的类似物保持相同。_{C 4}偶联产物相对于丁醇对丁二烯的选择性与路易斯酸阳离子的酸强度相关，如通过丙烯和丙酮的2-丙醇分解反应评估的那样，其中Ta是最具选择性的。_{与无定形 SiO 2}负载的阳离子相比，沸石负载阳离子的 C-C 耦合速率提高了一个数量级。

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Cascade Reaction of Ethanol to Butadiene over Ag-Promoted, Silica- or Zeolite-Supported Ta, Y, Pr, or La Oxide Catalysts

Ethanol converts to 1,3-butadiene in the presence of suitable multifunctional catalysts. In this work, Lewis acid cations Ta, Y, Pr, and La were dispersed on amorphous silica or β zeolite, and after physically mixing with silica-supported Ag nanoparticles, were tested in the cascade reaction of ethanol to butadiene at 573 K. The Lewis acid catalysts were characterized by X-ray fluorescence, N₂ physisorption, scanning transmission electron microscopy (STEM), X-ray diffraction, and diffuse reflectance (DR) UV–vis and X-ray photoelectron spectroscopies. High-resolution STEM images confirmed the small oxide cluster size on the silica support. Results from DR UV–vis spectroscopy showed that zeolite-supported Ta and Pr catalysts had a smaller metal oxide cluster size, relative to their SiO₂ counterparts. X-ray photoelectron spectroscopy confirmed that the oxidation state of the cations supported on the zeolite remained the same as that of their SiO₂-supported analogues. The selectivity of the C₄ coupling products toward butadiene relative to butanol correlated with the acid strength of the Lewis acid cations, as evaluated by the 2-propanol decomposition reaction to propene and acetone, with Ta being the most selective. The rate of C–C coupling over the zeolite-supported cations was enhanced by an order of magnitude compared to those cations supported on amorphous SiO₂.

更新日期：2023-02-21

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