Impact of Sn Lewis Acid Sites on the Dehydration of Cyclohexanol

IF 11.3 1区化学 Q1 CHEMISTRY, PHYSICAL

ACS Catalysis Pub Date : 2024-07-24 DOI:10.1021/acscatal.4c01608

Karen A. Resende, Ruixue Zhao, Yue Liu, Eszter Baráth, Johannes A. Lercher

引用次数: 0

Abstract

The impact of Sn on the concentration and strength of acid sites in Al containing zeolites with MFI topology and their catalytic activity for the dehydration of cyclohexanol in the aqueous phase has been investigated. The materials maintain constant Al concentrations and consequently Bro̷nsted acid site (BAS) concentrations, while exhibiting an increasing concentration of Sn Lewis acid sites (LAS). The presence of water alters LAS_(Sn), leading to weak BAS_(Sn) that increases the concentration of water in the zeolite micropore, while leaving the rate of dehydration of cyclohexanol unchanged. The TOF increases with the concentration of BAS_(Al) in close contact with framework LAS_(Sn), referred to as BAS_(Pair). The increase in the Arrhenius pre-exponential factor, without affecting the activation barrier (E_a), leads to the hypothesis that the proximity of both sites allows for a later transition state induced by the polarization of the C–O bond, leading in turn to a higher transition entropy.

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锡路易斯酸位点对环己醇脱水的影响

我们研究了锡对具有 MFI 拓扑结构的含铝沸石中酸性位点的浓度和强度的影响，以及它们对水相环己醇脱水的催化活性。这些材料的铝浓度保持不变，因此布罗恩斯泰德酸位点（BAS）的浓度也保持不变，而 Sn Lewis 酸位点（LAS）的浓度则不断增加。水的存在会改变 LAS(Sn)，导致弱 BAS(Sn)，从而增加沸石微孔中的水浓度，同时使环己醇的脱水率保持不变。TOF 随着与框架 LAS(Sn) 紧密接触的 BAS(Al) 浓度（称为 BAS(Pair)）的增加而增加。阿伦尼乌斯前指数因子的增加并不影响活化势垒（Ea），由此可以推测，这两个位点的接近使得 C-O 键的极化诱发了较晚的过渡状态，进而导致较高的过渡熵。

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

ACS Catalysis CHEMISTRY, PHYSICAL-

CiteScore

20.80

自引率

6.20%

发文量

1253

审稿时长

1.5 months

期刊介绍： ACS Catalysis is an esteemed journal that publishes original research in the fields of heterogeneous catalysis, molecular catalysis, and biocatalysis. It offers broad coverage across diverse areas such as life sciences, organometallics and synthesis, photochemistry and electrochemistry, drug discovery and synthesis, materials science, environmental protection, polymer discovery and synthesis, and energy and fuels. The scope of the journal is to showcase innovative work in various aspects of catalysis. This includes new reactions and novel synthetic approaches utilizing known catalysts, the discovery or modification of new catalysts, elucidation of catalytic mechanisms through cutting-edge investigations, practical enhancements of existing processes, as well as conceptual advances in the field. Contributions to ACS Catalysis can encompass both experimental and theoretical research focused on catalytic molecules, macromolecules, and materials that exhibit catalytic turnover.