Catalyst stability and deactivation remain significant hurdles, which hinder the realization of many promising chemical processes. This applies especially for biomass conversion over zeolitic materials, where the commonly applied solvothermal conditions adversely affect the stability of the catalysts. For example, tin-doped zeolite Beta, Sn-Beta, is one of the materials often used for a wide range of biomass reactions in the liquid phase. Herein, we present insights into the deactivation of Sn-Beta catalysts and assess different regeneration procedures. We identify tin and silicon leaching, along with tin restructuring into tin(IV) oxide, SnO₂, as the primary deactivation mechanisms during the conversion of biobased-derived glycolaldehyde in methanol/water solvents. Concurrently, the spent catalysts have a range of mesopores over a highly ordered and poorly defective zeolitic framework. Furthermore, we highlight the critical impact of reaction medium compositions affecting the leaching of tin and silicon and provide levers to mitigate it (e.g., higher alcohols, low water concentrations). Through the implementation of an oxidation–reduction–oxidation regeneration procedure, the catalyst contains twice as high active site concentrations as the use of conventional thermal oxidation. The oxidation–reduction–oxidation procedure reverses some of the ongoing deactivation (tin restructuring into SnO₂) with the transformation of the otherwise inactive SnO₂ into active sites. Together, the generated understanding of Sn-Beta deactivation and the successful application of a superior regeneration method can bring this family of catalysts closer to industrial applications.

中文翻译：

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用于液相生物质转化的 Sn-Beta 失活和还原再生

催化剂稳定性和失活仍然是重大障碍，阻碍了许多有前途的化学过程的实现。这尤其适用于沸石材料上的生物质转化，其中常用的溶剂热条件会对催化剂的稳定性产生不利影响。例如，掺锡沸石 Beta（Sn-Beta）是常用于各种生物质液相反应的材料之一。在此，我们提出了对 Sn-Beta 催化剂失活的见解并评估了不同的再生程序。我们确定锡和硅浸出以及锡重组为氧化锡（IV）SnO ₂是生物基乙醇醛在甲醇/水溶剂中转化过程中的主要失活机制。同时，废催化剂在高度有序且缺陷少的沸石骨架上具有一系列介孔。此外，我们强调了反应介质成分对锡和硅浸出的关键影响，并提供了减轻影响的手段（例如高级醇、低水浓度）。通过实施氧化-还原-氧化再生程序，催化剂的活性位点浓度是传统热氧化法的两倍。氧化-还原-氧化过程逆转了一些正在进行的失活（锡重组为 SnO _{2 ），将原本不活泼的 SnO 2}转化为活性位点。总之，对 Sn-Beta 失活的理解和卓越再生方法的成功应用可以使该系列催化剂更接近工业应用。