Abstract

Alkali and alkaline earth metal ions (Na⁺, K⁺, Cs⁺, Mg²⁺) exchanged MCM-22 zeolites were prepared and subsequently palladium (2 wt.%; Pd) was dispersed on above exchanged MCM-22 zeolite materials. All the MCM-22 materials were systematically characterized by FTIR, powder X-ray diffraction, N₂ sorption analysis and temperature-programmed desorption (TPD) of CO₂. The XRD pattern and FTIR data confirmed the existence of the MCM-22 framework structure even after exchanging bulky metal ions and palladium loading. TPD studies using CO₂ supports that the cesium and magnesium incorporated MCM-22 possess a strong and large number of basic sites. The alkali and alkaline-earth metal ions exchanged MCM-22 catalysts were explored for industrially important eugenol isomerisation, whereas the palladium containing MCM-22 materials were utilised for Heck coupling reaction of styrene with iodobenzene. The Cs-MCM-22 showed the best activity for the eugenol isomerization with the isoeugenol yield of 76%. The Cs/Pd-MCM-22 was shown as promising heterogeneous catalyst for Heck coupling reaction of styrene with iodobenzene and yield 99% stilbene. For both isomerization and Heck coupling reaction, the catalysts retain their activities even after several runs.

Graphic Abstract

Among different alkali and alkaline earth ion-exchanged MCM-22 materials, cesium containing MCM-22 was shown as a promising catalyst for isomerization of lignin-derived biomass model compound viz., eugenol. Subsequently, the palladium dispersed CsMCM-22 was found to be the potential catalyst for Heck coupling under ambient conditions.

中文翻译：

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碱/碱土金属离子交换和钯分散的MCM-22沸石作为丁香酚的异构化和Heck偶联反应的潜在催化剂

摘要

制备了碱和碱土金属离子（Na ⁺，K ⁺，Cs ⁺，Mg ²⁺）交换的MCM-22沸石，然后将钯（2 wt。％； Pd）分散在上述交换的MCM-22沸石材料上。通过FTIR，粉末X射线衍射，N ₂吸附分析和CO ₂的程序升温脱附（TPD）对所有MCM-22材料进行了系统表征。X射线衍射图谱和FTIR数据证实了MCM-22骨架结构的存在，即使在交换笨重的金属离子和负载钯之后也是如此。使用CO _2的TPD研究支持掺入铯和镁的MCM-22具有大量的基本位点。研究了碱金属和碱土金属离子交换的MCM-22催化剂在工业上重要的丁香酚异构化，而含钯的MCM-22材料用于苯乙烯与碘代苯的Heck偶联反应。Cs-MCM-22显示丁香酚异构化的最佳活性，异丁香酚的收率为76％。Cs / Pd-MCM-22被证明是有前途的多相催化剂，可用于苯乙烯与碘代苯的Heck偶联反应，产率为99％的1,2-苯乙烯。对于异构化和Heck偶联反应，即使经过几次运行，催化剂仍保持其活性。

图形摘要

在不同的碱金属和碱土金属离子交换的MCM-22材料中，含铯的MCM-22被证明是木质素衍生的生物质模型化合物即丁子香酚的异构化催化剂。随后，发现分散钯的CsMCM-22是在环境条件下进行Heck偶联的潜在催化剂。