A heteropoly acid based organic hybrid heterogeneous catalyst, HMQ-STW, was prepared by combining 8-hydroxy-2-methylquinoline (HMQ) with Keggin-structured H₄SiW₁₂O₄₀ (STW). The catalyst was characterized via elemental analysis, X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TG) and potentiometric titration analysis. The catalytic performance of the catalyst was assessed in the ketalization of ketones with glycol or 1,2-propylene glycol. Various reaction parameters, such as the glycol to cyclohexanone molar ratio, catalyst dosage, reaction temperature and time, were systematically examined. HMQ-STW exhibited a relatively high yield of corresponding ketal, with 100% selectivity under the optimized reaction conditions. Moreover, catalytic recycling tests demonstrated that the heterogeneous catalyst exhibited high potential for reusability, and it was revealed that the organic modifier HMQ plays an important role in the formation of a heterogeneous system and the improvement of structural stability. These results indicated that the HMQ-STW catalyst is a promising new type of heterogeneous acid catalyst for the ketalization of ketones.

中文翻译：

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8-Hydroxy-2-methylquinoline-modified H4SiW12O40：用于缩醛/缩酮形成的可重复使用的多相催化剂

_{通过将 8-羟基-2-甲基喹啉 (HMQ) 与 Keggin 结构的 H 4} SiW ₁₂ O ₄₀ (STW)结合制备杂多酸基有机杂化多相催化剂 HMQ-STW 。该催化剂通过以下方式表征元素分析，X射线衍射（XRD），傅里叶变换红外光谱（FT-IR），扫描电子显微镜（SEM），热重分析（TG）和电位滴定分析。在酮与乙二醇或 1,2-丙二醇的缩酮化反应中评估了催化剂的催化性能。系统地检查了各种反应参数，例如乙二醇与环己酮的摩尔比、催化剂用量、反应温度和时间。HMQ-STW 表现出相对较高的相应缩酮产率，在优化的反应条件下具有 100% 的选择性。此外，催化回收测试表明，非均相催化剂表现出很高的可重复使用潜力，揭示了有机改性剂HMQ对异质体系的形成和结构稳定性的提高具有重要作用。这些结果表明，HMQ-STW催化剂是一种很有前途的新型非均相酸催化剂，用于酮的缩酮化。