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For zeolite catalysts, the regulation of active site and pore structure plays an important role in the enhancement of their catalytic performance. In this work, a one‐pot and organic template‐free co‐regulation route is proposed to straightforwardly synthesize basic mesoporous ZSM‐5 zeolites with adjustable alkaline‐earth metal species. The synthesis pathway combines two decisive strategies: 1) the seed‐induced interface assembly growth method and 2) the acidic co‐hydrolysis/condensation of aluminosilicate species and alkaline‐earth metal (e.g. Mg, Ca, Sr, or Ba) sources. It is interesting that the mesoporous structure was self‐evolved through particle‐attached seed‐interfacial crystallization without the assistance of any template. Meanwhile, the incorporation of alkaline‐earth metals species is homogeneous and highly dispersed in the solid products during the whole crystallization process, and finally generate the superior basicity. Catalysis tests of the as‐synthesized samples displayed their novel performance in the typical base reaction of Knoevenagel condensation, even for bulky substrates owing to the enhanced diffusion arising from the meso/microporous network. This finding opens new possibilities for facile, cost‐effective, and environmentally friendly synthesis of mesoporous high‐silica zeolites with tunable acid/base properties, and deepens our understanding of the particle‐attached crystallization. [ABSTRACT FROM AUTHOR]

Diffusion limitation in micropores of zeolites leads to a demand for optimization of zeolite morphology and/or porosity. However, tailoring crystallization processes to realize targeted morphology/porosity is a major challenge in zeolite synthesis. On the basis of previous work on the salt-aided, seed-induced route, the template effect of seeds on the formation of micropores, mesopores and even macropores was further explored to selectively achieve desired hierarchical architectures. By carefully investigating the crystallization processes of two typical samples with distinct crystal morphologies, namely, 1) nanocrystallite-oriented self-assembled ZSM-5 zeolite and 2) enriched intracrystal mesoporous ZSM-5 zeolite, a detailed mechanism is proposed to clarify the role of silicalite-1 seeds in the formation of diverse morphologies in a salt-rich heterogeneous system, combined with the transformation of seed-embedded aluminosilicate gel. On the basis of these conclusions, the morphologies/porosities of products were precisely tailored by deliberately adjusting the synthesis parameters (KF/Si, tetrapropylammonium bromide/Si and H2O/Si ratios and type of organic template) to regulate the kinetics of seed dissolution and seed-induced recrystallization. This work may not only provide a practical route to control zeolite crystallization for tailoring crystal morphology, but also expands the knowledge of crystal growth mechanisms in a heterogeneous system. [ABSTRACT FROM AUTHOR]

A clear and deep understanding of zeolite crystallization with the addition of organosilane is desirable for the reasonable design and preparation of hierarchical zeolites. Herein, the effects of different organosilanes on zeolite crystallization were systematically studied. It was found that organosilane plays the role of an inhibitor in the silanization-based zeolite preparation, and this inhibition effect was determined by its participation degree. An organosilane with a high participation degree can result in the prolongation of nucleation and growth periods of zeolite as well as the variation of product properties. More importantly, a dynamic participation pathway of organosilane is proposed, that is, the growth of zeolite is accompanied by the continuous removal of organosilane, leading to an increase of product crystallinity as well as the decrease of mesoporosity. This study gives a new insight into the role that organosilane plays in zeolite crystallization, which will help to direct the rational selection of organosilane and design of crystallization condition for the optimal synthesis of hierarchical zeolites. [ABSTRACT FROM AUTHOR]

Frontispiece: Co-hydrolysis and Seed-Induced Synthesis of Basic Mesoporous ZSM-5 Zeolites with Enhanced Catalytic Performance Keywords: basic zeolite; Knoevenagel condensation; mesoporous zeolite; non-classical crystallization; seed-induced synthesis EN basic zeolite Knoevenagel condensation mesoporous zeolite non-classical crystallization seed-induced synthesis 1 1 1 05/18/20 20200515 NES 200515 B Basic mesoporous ZSM-5 b with adjustable alkaline-earth metal species has been subtly synthesized with the "meeting" of seed and co-hydrolysis method. Basic zeolite, Knoevenagel condensation, mesoporous zeolite, non-classical crystallization, seed-induced synthesis. [Extracted from the article]