Solid base catalysts featuring green, robustness, and high activity play an important role in the current fine-chemical and petrochemical industry. Normally, the generation of supported K₂O by thermal decomposition of KNO₃ requires high temperature, and this process can sometimes destroy the structure of supporting materials. We herein report a solvent-assisted stepwise redox (SASR) approach to generate zeolite NaA-supported K₂O, which we call K₂O/NaA, that function as the solid base catalyst for Michael addition reaction between ethanol and ethyl acrylate. The solvent-assisted redox decomposition process of KNO₃ at elevated temperature was investigated by thermogravimetry–mass spectrometry. It reveals that after reducing a minor amount of KNO₃ at 400 °C, the organic solvent decomposes to form carbon, which promotes the reduction of KNO₃ to generate strong basicity on the zeolite NaA at 600 °C. The resulting material, K₂O/NaA-S, exhibits improved catalytic activity in Michael addition reaction over other benchmark base catalysts that have been used in this reaction. This catalyst is durable for at least four catalytic cycles without apparent loss in activity. K₂O/NaA-S exhibits larger reaction rate constant yet lower activation energy than K₂O/NaA prepared by thermal decomposition method. The SASR approach described in this paper represents a new blueprint for the generation of the supported alkali oxide as the solid base catalyst.

中文翻译：

---

溶剂辅助逐步氧化还原法生成沸石NaA负载的K ₂ O作为强碱催化剂，用于迈克尔加成丙烯酸乙酯和乙醇

具有绿色，坚固性和高活性的固体碱催化剂在当前的精细化工和石化工业中起着重要的作用。通常，通过KNO ₃的热分解产生负载的K ₂ O需要高温，并且该过程有时会破坏负载材料的结构。我们在此报告了一种溶剂辅助的逐步氧化还原（SASR）方法来生成沸石NaA负载的K ₂ O，我们称其为K ₂ O / NaA，它充当乙醇和丙烯酸乙酯之间迈克尔加成反应的固体碱催化剂。KNO ₃的溶剂辅助氧化还原分解过程通过热重分析-质谱法研究了在高温下的温度。结果表明，在400°C下还原少量的KNO ₃后，有机溶剂分解形成碳，从而促进KNO ₃的还原，从而在600°C的NaA沸石上产生强碱性。与在该反应中使用的其他基准碱催化剂相比，所得材料K ₂ O / NaA-S在迈克尔加成反应中显示出改进的催化活性。该催化剂至少在四个催化周期内是耐用的，而没有明显的活性损失。ķ ₂ O / NaA型-S表现出较大的反应速度常数还低活化能于K ₂通过热分解法制得的O / NaA。本文描述的SASR方法代表了生成担载的碱金属氧化物作为固体碱催化剂的新蓝图。