探讨金属负载和焙烧温度对臭氧环氧化乙烯中AgOx/Al₂O₃催化剂性能的影响

IF 4.8 2区化学 Q2 CHEMISTRY, PHYSICAL

Applied Catalysis A: General Pub Date : 2025-09-04 DOI:10.1016/j.apcata.2025.120542

Nazanin Charchi Aghdam , Ning Chen , Beatriz Diaz Moreno , Jafar Soltan

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引用次数: 0

摘要

这项工作探索了乙烯的臭氧氧化环氧化，以生产环氧乙烷在AgOx/Al₂O₃催化剂上，这是一个新的反应途径，由于它最近出现，仍然未被充分开发。重点研究了载银量和煅烧温度对焙烧效果的影响。较高的银负荷量增加了载体表面银的丰度，加速了臭氧的分解，提高了表面氧的覆盖率。这种增强的氧气覆盖，以及减少乙烯吸附，促进环氧乙烷的直接形成，同时保持高转化率。含银量为10 wt%的催化剂，乙烯转化率为96 %，环氧乙烷选择性为68 %。将焙烧温度从350℃提高到750℃，改变了银的氧化态，提高了催化剂的稳定性和臭氧转化率。然而，没有观察到环氧乙烷选择性的显著增强，可能是由于在这些条件下表面氧覆盖率的改善有限。它们被认为有利于环氧化。利用原位对分布函数（PDF）分析研究了不同气氛下银的结构演化，揭示了加热过程中连续的氧化还原转变。总体而言，Ag负载对环氧乙烷选择性的影响比对焙烧温度的影响更为显著，表明Ag负载是优化臭氧氧化环氧化催化剂性能的关键因素。

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Probing the effects of metal loading and calcination temperature on AgOx/Al₂O₃ catalyst in ozonative epoxidation of ethylene

This work explores the ozonative epoxidation of ethylene to produce ethylene oxide over AgO_x/Al₂O₃ catalysts which is a novel reaction pathway that remains underexplored due to its recent emergence. The study focuses on the effects of silver loading and calcination temperature. Higher silver loading was found to increase the abundance of silver species on the support surface, which accelerates ozone decomposition and elevates surface oxygen coverage. This enhanced oxygen coverage, along with reduced ethylene adsorption, promotes the direct formation of ethylene oxide while maintaining high conversion rates. The catalyst with 10 wt% silver achieved an ethylene conversion of 96 % and an ethylene oxide selectivity of 68 %. Increasing the calcination temperature from 350 ºC to 750 ºC altered silver oxidation states and improved catalyst stability and ozone conversion. However, no significant enhancement in ethylene oxide selectivity was observed, likely due to limited improvement in surface oxygen coverage under those conditions. which are considered beneficial for epoxidation. Structural evolution of silver species under different atmospheres was investigated using in situ pair distribution function (PDF) analysis, revealing successive redox transformations during heating. Overall, Ag loading had a more significant impact on ethylene oxide selectivity than calcination temperature, highlighting it as a key factor in optimizing catalyst performance in ozonative epoxidation.

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来源期刊

Applied Catalysis A: General 化学-环境科学

CiteScore

9.00

自引率

5.50%

发文量

415

审稿时长

24 days

期刊介绍： Applied Catalysis A: General publishes original papers on all aspects of catalysis of basic and practical interest to chemical scientists in both industrial and academic fields, with an emphasis onnew understanding of catalysts and catalytic reactions, new catalytic materials, new techniques, and new processes, especially those that have potential practical implications. Papers that report results of a thorough study or optimization of systems or processes that are well understood, widely studied, or minor variations of known ones are discouraged. Authors should include statements in a separate section "Justification for Publication" of how the manuscript fits the scope of the journal in the cover letter to the editors. Submissions without such justification will be rejected without review.