This review addresses the recent developments and trends in tailoring the nature and local properties of active sites in zeolite-based catalysts, with a special focus on novel extra-large pore, layered (2D), nanocrystalline, and hierarchical (mesoporous) zeolites with enhanced pore accessibility. In the first part of the review, we discuss the latest achievements in the bottom-up (direct synthesis) and top-down (post-synthesis) approaches for isomorphous substitution in zeolites enabling control over the type (Bronsted, Lewis, or both), amount, strength, and location of acid sites. The benefits in catalysis provided by such zeolites with tuned acidity and improved accessibility are shown for different acid-catalyzed reactions involving bulky molecules, as in the synthesis of fine chemicals and biomass transformations. The incorporation of metal species of different sizes (increasing from single atoms to clusters and to nanoparticles) in zeolites allows expanding the set of reactions catalyzed by these materials. The main preparation strategies for designing metal–zeolite catalysts, especially those offering control over the size of the metal species, and their catalytic behaviour in industrially relevant and emerging sustainable catalytic processes are dealt with in the second part of the review. Particular attention is paid to the stabilization of size-controlled small metal clusters and nanoparticles through their encapsulation in the voids of zeolite frameworks as well as to the dynamic behaviour of the metal species under reactive environments with important implications in catalysis. The need for using advanced operando spectroscopic and imaging tools to unveil the precise nature and functioning of the active sites in working zeolites is emphasized. The information gathered in this review is expected to provide guidance for developing more efficient zeolite-based catalysts for existing and new applications.

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New trends in tailoring active sites in zeolite-based catalysts.

Since the first connection between Fenton chemistry and biomedicine, numerous studies have been presented in this field. Comprehensive presentation of the guidance from Fenton chemistry and a summary of its representative applications in cancer therapy would help us understand and promote the further development of this field. This comprehensive review first supplies basic information regarding Fenton chemistry, including Fenton reactions and Fenton-like reactions. Subsequently, the current progress of Fenton chemistry is discussed, with some corresponding representative examples presented. Furthermore, the current strategies for further optimizing the performance of chemodynamic therapy guided by Fenton chemistry are highlighted. Most importantly, future perspectives on the combination of biomedicine with Fenton chemistry or a wider range of catalytic chemistry approaches are presented. We hope that this review will attract positive attention in the chemistry, materials science, and biomedicine fields and further tighten their connections.

Biomedicine Meets Fenton Chemistry.

Hierarchical zeolites: Synthesis and catalytic properties

Adding mesopore networks in microporous materials using the principles of hierarchical structure design is recognized as a promising route for eliminating their transport limitations and, therefore, for improving their value in technological applications. Depending on the routes of physico-chemical procedures or post-synthesis treatments used, very different geometries of the intentionally-added transport mesopores can be obtained. Understanding the structure-dynamics relationships in these complex materials with multiple porosities under different thermodynamical conditions remains a challenging task. In this review, we summarize the results obtained so far on experimental and theoretical studies of diffusion in micro-mesoporous materials. By considering four common classes of bi-porous materials, which are differing by the inter-connectivities of their sup-spaces as one of the most important parameter determining the transport rates, we discuss their generic transport properties and correlate the results delivered by the equilibrium and non-equilibrium techniques of diffusion measurements.

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Transport properties of hierarchical micro–mesoporous materials

A critical review on graphitic carbon nitride (g-C3N4)-based materials: Preparation, modification and environmental application

Conversion of biomass derived carbohydrates to alkyl levulinates is an important process due to the wide application of alkyl levulinates as chemicals and biofuel additives. Efficient conversion of cheap and abundant glucose to alkyl levulinates over easily separated and regenerated solid catalyst is highly desirable. Here, the transformation of glucose to methyl levulinate (MLE) was studied over dual solid acid catalysts. The synergistic effect of solid Bronsted (B) acid and solid Lewis (L) acid was observed. A combined catalyst system consisting of both B acid and L acid was found to be more efficient for the production of MLE from glucose. 62% yield of MLE was given over the combined catalyst of SO 4 2− /ZrO 2 and Sn-Beta prepared by postsynthesis method at 170 °C for 24 h. The roles of L acid sites of SO 4 2− /ZrO 2 and Sn-Beta, and B acid sites of SO 4 2− /ZrO 2 were discussed in detail. Alternative biomass-derived carbohydrates also gave moderate to good yields of MLE. Recyclability studies indicated that the combined catalyst system can be reused without significant change in the yield of MLE, proving its easy recovery and thermal stability during regeneration.

Direct catalytic conversion of carbohydrates to methyl levulinate: Synergy of solid Bronsted acid and Lewis acid

Transition-metal-catalyzed transfer hydrogenation with an in situ hydrogen donor has received a great deal of attention from both academia and industry as an alternative to the traditional high-pre...

Recent Advances in Catalytic Transfer Hydrogenation with Formic Acid over Heterogeneous Transition Metal Catalysts

Fluoride-free and low concentration template synthesis of hierarchical Sn-Beta zeolites: efficient catalysts for conversion of glucose to alkyl lactate

Rapid synthesis of Sn-containing nanosized all-silica Beta zeolite was developed in this work. The method employed all-silica Beta (Si-Beta) as parent, which was crystallized in several hours by the hydrothermal method, and incorporated Sn to Si-Beta through grinding with SnCl4·5H2O and subsequent calcination procedure. The prepared Sn-Beta zeolites were analyzed by several methods including XRD, SEM, N2 physisorption, FT-IR spectroscopy of deuterated acetonitrile and pyridine adsorption, UV–vis DR, and XPS. The mechanism of incorporation of Sn sites into the framework of zeolite was revealed. The results show that the successful incorporation of Sn sites strongly depends on the crystallinity of the parent Si-Beta. Si-Beta with lower crystallinity (<90%) had a considerable amount of silanols which provided sites for Sn incorporation into the framework sites. For Si-Beta with higher crystallinity and less silanols, desilication was used to generate more silanols for the incorporation of Sn sites. The prepa...

Tianliang Lu

Papers

Direct catalytic conversion of carbohydrates to methyl levulinate: Synergy of solid Bronsted acid and Lewis acid

Recent Advances in Catalytic Transfer Hydrogenation with Formic Acid over Heterogeneous Transition Metal Catalysts

Fluoride-free and low concentration template synthesis of hierarchical Sn-Beta zeolites: efficient catalysts for conversion of glucose to alkyl lactate

Synthesis of Sn-Containing Nanosized Beta Zeolite As Efficient Catalyst for Transformation of Glucose to Methyl Lactate

Conversion of dihydroxyacetone to methyl lactate catalyzed by highly active hierarchical Sn-USY at room temperature