International audienceWith the necessity for the refining industry to treat heavier feedstocks, there is a clear demand for improved zeolite materials displaying better accessible surface areas and higher pore volumes in order to capitalize on their effectiveness. To this end, over the last decade, there has been an intensification of research on the exploration of new routes to synthesize zeolite materials combining micropores with mesopores. Different synthesis strategies are used for their preparation (i.e., by structure breaking or so-called 'destructive' pathways, or structure building or so-called 'constructive' synthesis pathways). This Review discusses the variety of current synthesis strategies, while emphasizing the strengths and weaknesses of the different routes regarding material characteristics; health, safety, and environment aspects; and synthesis costs

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Understanding the internal structure of ZSM-5 crystallites is essential for improving catalyst performance. In this work, a combination of fluorescence microscopy, AFM, SEM, and optical observations is employed to study intergrowth phenomena and pore accessibility in a set of five ZSM-5 samples with different crystal morphologies. An amine-functionalized perylene dye is used to probe acid sites on the external crystal surface, while DAMPI (4-(4-diethylaminostyryl)- N-methylpyridinium iodide) is used to map access to the straight channels in MFI from the outer surface. The use of these dyes is validated by studying the well-understood rounded-boat type ZSM-5 crystals. Next coffin-shaped ZSM-5 crystals are considered; we critically evaluate the seemingly conflicting 2-component and 3-component models that have been proposed to account for the hourglass structure in these crystals. The data prove that observation of an hourglass structure is essentially unrelated to a 90 degree rotation of the pyramidal crystal components under the (010) face. Hence, in perfectly formed coffin-shaped crystals, the straight channels can be accessed from (010). However, in other crystal batches, sections with a 90 degrees rotation can be found; they are indeed located inside the crystal sections under (010) but often only partially occupy these pyramidal components. In such a case, both straight and sinusoidal pores surface at the hexagonal face. The results largely support the 3-component model, but with the added notion that 90 degree rotated sections (as proposed in the 2-component model) are most likely to be formed inside the defect-rich, pyramidal crystal sections under the (010) faces.

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Effektive Poren: Zeolith‐Y‐Kristalle mit Mikroporen (ca. 1 nm), kleinen (ca. 3 nm) und großen Mesoporen (ca. 30 nm) wurden aus zuvor mit Dampf und Säure behandeltem Material durch Auslaugen mit Base erhalten. Die Zeolith‐Y‐Kristalle mit trimodaler Porosität (siehe elektronentomographische Aufnahme) zeigen beim Hydrocracking eine nahezu ideale Selektivität für und erhöhte Ausbeuten an Kerosin und Diesel.

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Combinatorial strategies are for the first time applied in membrane technology and prove to be a powerful new tool in the search for novel membrane materials. The selected system for this study is a polyimide solvent-resistant nanofiltration membrane prepared via phase inversion. The phase inversion process is a typical membrane synthesis procedure involving a large number of compositional components, which can each be varied in a wide concentration range. The optimization of the membrane dope composition was performed using evolutionary optimization via genetic algorithms. Compared with the best commercially available membranes, a substantially improved membrane performance could be realized, both on the level of membrane selectivity and on that of permeability. The miniaturized high-throughput synthesis procedure could be scaled up successfully when the polymer dope was sufficiently viscous. It can be anticipated that application of combinatorial techniques can potentially lead to major improvements in all fields of membrane technology, for example water treatment, gas separation, and dialysis, not only on the compositional level but also for instance on the level of membrane synthesis posttreatment and operational conditions.

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