Cs-Beta with an Al-rich composition as a highly active base catalyst for Knoevenagel condensation

Otomo, Ryoichi; Osuga, Ryota; Kondo, Junko N.; Kamiya, Yuichi; Yokoi, Toshiyuki

doi:10.1016/j.apcata.2019.02.014

Cited by 22 publications

(21 citation statements)

References 34 publications

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“…Another probe that has been used to characterize basic sites is chloroform. Recently, the IR study of chloroform was used to demonstrate that by tuning the properties of the framework, Cs-exchanged zeolite beta could exhibit sites of equivalent strength to faujasite-type zeolites, which are widely studied because of the high ion-exchange capacities and strong basicity they display (Figure d) . As an amphoteric probe molecule, pyrrole can adsorb on both Lewis acids and Lewis bases, with the main N–H stretching bands attributed to the interaction with basic framework oxygen atoms adjacent to the alkali cations.…”

Section: Alkali and Alkaline Earth Metalsmentioning

confidence: 99%

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Single-Atom Catalysts across the Periodic Table

et al. 2020

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Isolated atoms featuring unique reactivity are at the heart of enzymatic and homogeneous catalysts. In contrast, although the concept has long existed, single-atom heterogeneous catalysts (SACs) have only recently gained prominence. Host materials have similar functions to ligands in homogeneous catalysts, determining the stability, local environment, and electronic properties of isolated atoms and thus providing a platform for tailoring heterogeneous catalysts for targeted applications. Within just a decade, we have witnessed many examples of SACs both disrupting diverse fields of heterogeneous catalysis with their distinctive reactivity and substantially enriching our understanding of molecular processes on surfaces. To date, the term SAC mostly refers to late transition metal-based systems, but numerous examples exist in which isolated atoms of other elements play key catalytic roles. This review provides a compositional encyclopedia of SACs, celebrating the 10th anniversary of the introduction of this term. By defining single-atom catalysis in the broadest sense, we explore the full elemental diversity, joining different areas across the whole periodic table, and discussing historical milestones and recent developments. In particular, we examine the coordination structures and associated properties accessed through distinct single-atom−host combinations and relate them to their main applications in thermo-, electro-, and photocatalysis, revealing trends in element-specific evolution, host design, and uses. Finally, we highlight frontiers in the field, including multimetallic SACs, atom proximity control, and possible applications for multistep and cascade reactions, identifying challenges, and propose directions for future development in this flourishing field.

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Section: Alkali and Alkaline Earth Metalsmentioning

confidence: 99%

Section: Alkali and Alkaline Earth Metalsmentioning

confidence: 99%

Single-Atom Catalysts across the Periodic Table

et al. 2020

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“…Knoevenagel condensation is one of the most compelling reactions to achieve C=C bond formation from aldehydes/ketones or other compounds with active methylene during organic synthesis [142,143]. Such a process is typically catalyzed by weak acids, bases, or acid-base sites of H-MOF catalysts.…”

Section: Knoevenagel Condensationmentioning

confidence: 99%

Application of hierarchically porous metal-organic frameworks in heterogeneous catalysis: A review

et al. 2021

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Hierarchically porous metal-organic frameworks (H-MOFs) with micro-, meso-and macropores have emerged as a popular class of crystalline porous materials that have attracted extensive interests, and they have been studied in diverse applications, especially in heterogeneous catalysis. The hierarchical structures enable sufficient diffusion and accessibility to the active sites of the molecules and permit the encapsulation of catalytic guest molecules to exploit more possibilities with enhanced catalytic performance. In this review, we have summarized the recent representative developments of H-MOFs in the field of heterogeneous catalysis, which includes oxidation reaction, hydrogenation reaction, and condensation reaction. Emphasis is placed on the multiple functions of hierarchical structures, and the catalytic activity, selectivity, stability, recyclability, etc. of the industrial utility of H-MOFs. Finally, the prospects and challenges of H-MOFs in heterogeneous catalysis and the remaining issues in this field are presented.

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“…[13][14][15] Metals, especially transition metals, have been extensively applied in a series of important organic transformations as heterogeneous catalysts such as nanoparticles (NPs), metalorganic framework (MOF), clusters, coordination metal complexes, or free ions. [16][17][18][19][20][21] Despite their high efficiency, these catalysts have some drawbacks such as significant environmental effects, metal leaching, high price, gas poisoning susceptibility, poor durability, and low selectivity. Thus, metal-free, and recyclable catalysts are crucial for both environmental remediation and large-scale industrial applications.…”

Section: Introductionmentioning

confidence: 99%