Theoretical Investigation of Propylene Epoxidation Using H2 and O2 Over Titanosilicate-Supported Au Catalysts

IF 2.3 4区化学 Q3 CHEMISTRY, PHYSICAL

Catalysis Letters Pub Date : 2024-07-30 DOI:10.1007/s10562-024-04783-y

Yasutaka Hamada, Tomohisa Yonemori, Yuhki Ishimaru, Takashi Kawakami, Shusuke Yamanaka, Mitsutaka Okumura

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Abstract

Titanosilicate-supported Au-cluster catalysts can be used to selectively synthesize propylene oxide from propylene using O₂ and H₂. However, the details of the catalytic reaction mechanism have not yet been elucidated. Thus, the reaction mechanism was investigated using density functional theory calculations. The calculation results revealed that active Ti-OOH forms on the surface Ti site, which is active as an oxidant and acts as an anchorage site for Au nanoclusters. The rate-determining step of propylene oxide synthesis on Au/titanosilicate is O insertion into propylene, with an activation energy of 1.37 eV. The propylene involved in this reaction is activated by adsorption on Au nanoclusters. Moreover, it was also found that the formation of Ti-OOH on Au/titanosilicate requires an activation energy of 0.48 eV, while it is barrierless on Au/anatase-TiO₂. However, the decomposition energy of Ti-OOH on Au/titanosilicate is −0.16 eV, which is smaller than that on Au/anatase-TiO₂ (−1.12 eV). The results indicate that Ti-OOH decomposes more readily on Au/titanosilicate than on Au/anatase-TiO₂ but is easily regenerated because the reaction energy is significantly smaller than that on Au/anatase-TiO₂. Therefore, these calculations are qualitatively in good agreement with the experimental results for Au/titanosilicate, which exhibited high catalytic activity at high temperatures.

Graphical Abstract

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在钛硅酸盐支撑的金催化剂上使用 H2 和 O2 进行丙烯环氧化的理论研究

钛硅酸盐支撑的金簇催化剂可用于利用 O2 和 H2 从丙烯中选择性地合成环氧丙烷。然而，催化反应机理的细节尚未阐明。因此，我们利用密度泛函理论计算对反应机理进行了研究。计算结果表明，活性 Ti-OOH 形成于表面 Ti 位点上，Ti 位点作为氧化剂具有活性，同时也是金纳米团簇的锚定位点。金/钛硅酸盐上合成环氧丙烷的速率决定步骤是 O 插入丙烯，活化能为 1.37 eV。参与该反应的丙烯通过吸附在金纳米团簇上而被激活。此外，研究还发现，在金/钛硅酸盐上形成 Ti-OOH 需要 0.48 eV 的活化能，而在金/金酸盐-二氧化钛上则无障碍。然而，Ti-OOH 在金/钛硅酸盐上的分解能为-0.16 eV，小于在金/金酸盐-二氧化钛上的分解能（-1.12 eV）。结果表明，Ti-OOH 在 Au/titanosilicate 上比在 Au/anatase-TiO2 上更容易分解，但由于反应能明显小于 Au/anatase-TiO2 上的反应能，因此很容易再生。因此，这些计算结果与金/钛硅酸盐的实验结果在性质上非常吻合，后者在高温下表现出很高的催化活性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Catalysis Letters 化学-物理化学

CiteScore

5.70

自引率

3.60%

发文量

327

审稿时长

1 months

期刊介绍： Catalysis Letters aim is the rapid publication of outstanding and high-impact original research articles in catalysis. The scope of the journal covers a broad range of topics in all fields of both applied and theoretical catalysis, including heterogeneous, homogeneous and biocatalysis. The high-quality original research articles published in Catalysis Letters are subject to rigorous peer review. Accepted papers are published online first and subsequently in print issues. All contributions must include a graphical abstract. Manuscripts should be written in English and the responsibility lies with the authors to ensure that they are grammatically and linguistically correct. Authors for whom English is not the working language are encouraged to consider using a professional language-editing service before submitting their manuscripts.