吸附量热技术和多相催化微观动力学

本文介绍了多相催化研究中的吸附量热技术、多相催化微观动力学及其计算机模拟, 以及吸附量热技术在定量表征固体催化剂表面中心和在多相催化微观动力学分析中的重要作用。     

多相催化中的溢流作用

详细介绍和评述了30 余年来有关溢流的研究进展, 包括溢流这一概念的内涵及其对多相催化学科的影响, 常见的溢流现象、溢流效应及利用溢流效应进行催化剂设计的有关问题; 对未来溢流研究的方向提出了建议。     

稀土金属在不对称催化中的应用:从均相催化到异相催化

稀土金属的配位数较高,可通过容纳大型手性配体,构筑手性环境,催化不对称反应的定向发生,在工业生产特别是制药工程中具有重要应用价值.本文以Henry反应、Mannich反应和Strecker反应为例,总结回顾了稀土金属催化剂在此类反应中的设计思路、性能特点与应用前景,旨在展现稀土金属催化剂兼具融合均相催化与异相催化的优势...     

Frustrated Lewis Pairs in Heterogeneous Catalysis: Theoretical Insights

Frustrated Lewis pair (FLP) catalysts have attracted much recent interest because of their exceptional ability to activate small molecules in homogeneous catalysis. In the past ten years, this unique catalysis concept has been extended to heterogeneous catalysis, with much success. Herein, we review the recent theoretical advances in understanding FLP-based heterogeneous catalysis in several applications, including metal oxides, functionalized surfaces, and two-dimensional materials. A better understanding of the details of the catalytic mechanism can help in the experimental design of novel heterogeneous FLP catalysts.     

Heterogeneous Catalysis and Parahydrogen-Induced Polarization

Parahydrogen-induced polarization with heterogeneous catalysts (HET-PHIP) has been a subject of extensive research in the last decade since its first observation in 2007. While NMR signal enhancements obtained with such catalysts are currently below those achieved with transition metal complexes in homogeneous hydrogenations in solution, this relatively new field demonstrates major prospects for a broad range of advanced fundamental and practical applications, from providing catalyst-free hyperpolarized fluids for biomedical magnetic resonance imaging (MRI) to exploring mechanisms of industrially important heterogeneous catalytic processes. This review covers the evolution of the heterogeneous catalysts used for PHIP observation, from metal complexes immobilized on solid supports to bulk metals and single-atom catalysts and discusses the general visions for maximizing the obtained NMR signal enhancements using HET-PHIP. Various practical applications of HET-PHIP, both for catalytic studies and for potential production of hyperpolarized contrast agents for MRI, are described.     

Conjugated Microporous Polymers for Heterogeneous Catalysis

Conjugated microporous polymers (CMPs) are a class of crosslinked polymers that combine permanent micropores with π‐conjugated skeletons and possess three‐dimensional (3D) networks. Compared with conventional materials such as metal–organic frameworks (MOFs) and covalent organic frameworks (COFs), CMPs usually have superior chemical and thermal stability. CMPs have made significant progress in heterogeneous catalysis in the past seven years. With a bottom‐up strategy, catalytic moieties can be directly introduced into in the framework to produce heterogeneous CMP catalysts. Higher activity, stability, and selectivity can be obtained with heterogeneous CMP catalysts in comparison with their homogeneous analogs. In addition, CMP catalysts can be easily isolated and recycled. In this review, we focus on CMPs as an intriguing platform for developing various highly efficient and recyclable heterogeneous catalysts in organic reactions. The design, synthesis, and structure of these CMP catalysts are also discussed in this focus review.     

组合多相催化研究进展*

本文对组合多相催化研究进展进行了较全面的综述,介绍了组合多相催化过程、样品库制备、库表征-高通量筛选技术及相应的微型组合反应器,并讨论了组合多相催化技术的发展趋势.     

Heterogeneous Catalysis to Drive the Waste-to-Pharma Concept: From Furanics to Active Pharmaceutical Ingredients

A perspective on the use of heterogeneous catalysis to drive the waste-to-pharma concept is provided in this contribution based on the conversion of furanics to active pharmaceutical ingredients (APIs). The provided overview of the concept in this perspective article has been exemplified for two key molecule examples: Ancarolol and Furosemide.     

Perylene-Grafted Silicas: Mechanistic Study and Applications in Heterogeneous Photoredox Catalysis

A mechanistic study is herein presented for the use of heterogeneous photocatalysts based on perylene moieties. First, the successful immobilization of perylene diimides (PDI) on silica matrices is demonstrated, including their full characterization by means of electronic microscopy, surface area measurements, powder XRD, thermogravimetric analysis, and FTIR, ²⁹Si and ¹³C solid-state NMR, fluorescence, and diffuse reflectance spectroscopies. Then, the photoredox activity of the material was tested by using two model reactions, alkene oxidation and 4-nitrobenzylbromide reduction, and mechanistic studies were performed. The mechanistic insights into their photoredox activity show they have promising dual photocatalytic activity for both organic oxidations and reductions.     

Nanoscale Magnetic Stirring Bars for Heterogeneous Catalysis in Microscopic Systems

Nanometer‐sized magnetic stirring bars containing Pd nanoparticles (denoted as Fe₃O₄‐NC‐PZS‐Pd) for heterogeneous catalysis in microscopic system were prepared through a facile two‐step process. In the hydrogenation of styrene, Fe₃O₄‐NC‐PZS‐Pd showed an activity similar to that of the commercial Pd/C catalyst, but much better stability. In microscopic catalytic systems, Fe₃O₄‐NC‐PZS‐Pd can effectively stir the reaction solution within microdrops to accelerate mass transfer, and displays far better catalytic activity than the commercial Pd/C for the hydrogenation of methylene blue in an array of microdroplets. These results suggested that the Fe₃O₄‐NC‐PZS‐Pd could be used as nanoscale stirring bars in nanoreactors.     

氮掺杂多孔炭材料的制备及在多相催化中的应用

氮掺杂多孔炭材料,不仅具有多孔炭材料的较高的比表面积、丰富的孔结构、良好的稳定性及耐高温耐酸碱性等优点,同时氮原子的引入使材料表现出优异的导电性能及电子传输能力,使得炭材料具有了一定的碱性及催化性能,是目前多相催化及材料领域的一个研究热点。本文综述了氮掺杂多孔炭的制备方法及在多相催化中的应用,并指出了该领域未来研发的重点及应用前景。     

Nanoporous Metals for Heterogeneous Catalysis: Following the Success of Raney Nickel

Nanoporous metals (NPMs) with diversified shapes and compositions can be readily fabricated by dealloying monolithic alloys through chemical or electrochemical processes. Benefited from their high surface area, high density of low-coordinated sites on the ligament surface, and unsupported character, NPMs have attracted increasing attentions as a new class of heterogeneous catalysts with high activity, selectivity, and long-term stability, reminiscent of the great success of Raney nickel. In the present minireview, we summarize the recent advances in this exciting field and provide a critical discussion of the nature of their active sites and the structure–property correlation.     

Model Studies in Heterogeneous Catalysis. From Structure to Kinetics

Summary. Heterogeneous catalysis is one of the fields of modern technology, where the application of complex inorganic materials is of enormous economical importance. For a long time, the chemical and structural complexity of catalyst materials has precluded detailed insights into chemical processes on catalyst surfaces. In the last decades, however, substantial progress has been made toward a microscopic-level understanding of reaction mechanisms and kinetics, mainly based on the development of new well-defined model systems and on advances in experimental technology and theory. Scrutinizing the example of supported model catalysts, we review some of these innovations in model catalysis. As a particular challenging aspect of todays work, we discuss the question how detailed structural information on the model systems can be linked to catalytic reaction kinetics at the microscopic level.This revised version was published online in February 2005. In the previous version the issue was not marked as a special issue, and the issue title and the editor was missing     

Shape Engineering of Oxide Nanoparticles for Heterogeneous Catalysis

The fabrication of oxide particles with tunable sizes and shapes at the nanoscale is one of the most crucial issues for the design and development of highly efficient heterogeneous catalysts. The shape of oxide nanoparticles has been demonstrated to affect their catalytic properties remarkably. Tuning the shape of oxide particles allows preferential exposure of specific reactive facets; this can maximize the number of active sites available to the reactants, which can improve the activity and also mediate the reaction route to a specific channel to achieve higher selectivity for a particular chemical reaction. In addition, the shape of the oxide particles affects their interaction with metal particles or clusters, and this involves interfacial strain and charge transfer. Metal particles or clusters dispersed on the reactive or polar facets of the oxide support often provide superior catalytic performance, primarily because of strong metal–support interactions. However, the geometric and electronic features of the metal‐oxide interface may change during the course of the reaction, induced by chemisorption of reactive molecules at elevated temperatures, which should be taken into account in proposing a structure–reactivity relationship.     

Water Oxidation with Molecularly Defined Iridium Complexes: Insights into Homogeneous versus Heterogeneous Catalysis

Molecularly defined Ir complexes and different samples of supported IrO₂ nanoparticles have been tested and compared in the catalytic water oxidation with cerium ammonium nitrate (CAN) as the oxidant. By comparing the activity of nano‐scaled supported IrO₂ particles to the one of organometallic complexes it is shown that the overall activity of the homogeneous Ir precursors is defined by both the formation of the homogeneous active species and its conversion to Ir^IV ‐ oxo nanoparticles. In the first phase of the reaction the activity is dominated by the homogeneous active species. With increasing reaction time, the influence of nano‐sized Ir ‐ oxo particles becomes more evident. Notably, the different conversion rates of the homogeneous precursor into the active species as well as the conversion into Ir‐oxo nanoparticles and the different particle sizes have a significant influence on the overall activity. In addition to the homogeneous systems, IrO₂@MCM‐41 has also been synthesized, which contains stabilized nanoparticles of between 1 and 3 nm in size. This latter system shows a similar activity to IrCl₃ ? xH₂O and complexes 4 and 5 . Mechanistic insights were obtained by in situ X‐ray absorption spectroscopy and scanning transmission electron microscopy.     

Combined Heterogeneous Metal/Chiral Amine: Multiple Relay Catalysis for Versatile Eco‐Friendly Synthesis

Herein is described a versatile and broad synergistic strategy for expansion of chemical space and the synthesis of valuable molecules (e.g. carbocycles and heterocycles), with up to three quaternary stereocenters, in a highly enantioselective fashion from simple alcohols (31 examples, 95:5 to >99.5:0.5 e.r.) using integrated heterogeneous metal/chiral amine multiple relay catalysis and air/O₂ as the terminal oxidant. A novel highly 1,4‐selective heterogeneous metal/amine co‐catalyzed hydrogenation of enals was also added to the relay catalysis sequences.