Scholarlink

<p>Understanding the distinct roles of Brønsted and Lewis acid sites remains a great challenge in designing zeolite catalysts, as their coexistence often obscures mechanistic understanding. Here, we combine solid-state NMR spectroscopy with density functional theory to elucidate the site-specific pathways of ethanol dehydration to ethylene over ZSM-5 zeolite. Two key intermediates are identified: chemisorbed ethanol on Lewis acid sites (LAS) and surface ethoxy species on Brønsted acid sites (BAS), both formed via -OH activation followed by β-H elimination to yield ethylene. Comparative analysis reveals a thermodynamic–kinetic trade-off between the two sites. LAS facilitates low-temperature -OH activation but exhibits high barriers for β-H elimination, limiting ethylene formation. In contrast, BAS requires higher activation energy for -OH activation but enables more facile β-H elimination, promoting ethylene production. This intrinsic trade-off, governed by the thermodynamics of -OH activation, provides a mechanistic basis for understanding and tuning alcohol dehydration on zeolite acid sites.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Unveiling the thermodynamic-kinetic trade-off effect on acid sites in zeolite-catalyzed alcohol dehydration

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2026年3月9日

查看全文
  • Min Hu,
  • Yueying Chu,
  • Chao Wang,
  • Wenjin Cai,
  • Qiang Wang,
  • Jun Xu,
  • Feng Deng

摘要

Understanding the distinct roles of Brønsted and Lewis acid sites remains a great challenge in designing zeolite catalysts, as their coexistence often obscures mechanistic understanding. Here, we combine solid-state NMR spectroscopy with density functional theory to elucidate the site-specific pathways of ethanol dehydration to ethylene over ZSM-5 zeolite. Two key intermediates are identified: chemisorbed ethanol on Lewis acid sites (LAS) and surface ethoxy species on Brønsted acid sites (BAS), both formed via -OH activation followed by β-H elimination to yield ethylene. Comparative analysis reveals a thermodynamic–kinetic trade-off between the two sites. LAS facilitates low-temperature -OH activation but exhibits high barriers for β-H elimination, limiting ethylene formation. In contrast, BAS requires higher activation energy for -OH activation but enables more facile β-H elimination, promoting ethylene production. This intrinsic trade-off, governed by the thermodynamics of -OH activation, provides a mechanistic basis for understanding and tuning alcohol dehydration on zeolite acid sites.