Effect of External Surface Diffusion Barriers on Platinum/Beta-Catalyzed Isomerization of n-Pentane,Angewandte Chemie International Edition

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Effect of External Surface Diffusion Barriers on Platinum/Beta-Catalyzed Isomerization of n-Pentane
Angewandte Chemie International Edition ( IF 16.1 ) Pub Date : 2021-04-15 , DOI: 10.1002/anie.202104859
Shen Hu ₁ , Junru Liu ₁ , Guanghua Ye ₁ , Xinggui Zhou ₁ , Marc-Olivier Coppens ₂ , Weikang Yuan ₁

Affiliation

We have developed a generalizable strategy to quantify the effect of surface barriers on zeolite catalysis. Isomerization of n-pentane, catalyzed by Pt/Beta, is taken as a model reaction system. Firstly, the surface modification by chemical liquid deposition of SiO₂ was carried out to control the surface barriers on zeolite Beta crystals. The deposition of SiO₂ leads to a very slight change in the physical properties of Beta crystals, but an obvious reduction in Brønsted acid sites. Diffusion measurements by the zero-length column (ZLC) method show that the apparent diffusivity of n-pentane can be more than doubled after SiO₂ deposition, indicating that the surface barriers have been weakened. Catalytic performance was tested in a fixed-bed reactor, showing that the apparent catalytic activity improved by 51–131 % after SiO₂ deposition. These results provide direct proof that reducing surface barriers can be an effective route to improve zeolite catalyst performance deteriorated by transport limitations.

中文翻译：

外表面扩散屏障对铂/β催化正戊烷异构化的影响

我们开发了一种通用策略来量化表面屏障对沸石催化的影响。Pt/Beta 催化的正戊烷异构化被作为模型反应体系。首先，通过化学液相沉积SiO ₂进行表面改性，以控制β 沸石晶体的表面势垒。SiO ₂的沉积导致β晶体的物理性质发生非常轻微的变化，但布朗斯台德酸位点明显减少。零长度柱 (ZLC) 方法的扩散测量表明，使用 SiO ₂后，正戊烷的表观扩散率可以增加一倍以上沉积，表明表面屏障已被削弱。在固定床反应器中测试催化性能，表明在SiO ₂沉积后表观催化活性提高了51-131% 。这些结果提供了直接证据，证明减少表面屏障可以是改善因传输限制而劣化的沸石催化剂性能的有效途径。

更新日期：2021-06-16

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