Design of MFI Zeolite-Based Composites with Hierarchical Pore Structure: A New Generation of Structured Catalysts

Abstract

Zeolite/glass composite materials with hierarchical trimodal pore size distributions have been successfully prepared and subsequently characterized. Starting from glass monoliths having meso-and macropores, additional microporosity was introduced while allowing the growth of zeolite crystals via partial recrystallization of the glass support into ZSM-5 zeolite phase. Structured zeolitic catalytic materials were produced using a combination of supramolecular templating methods to produce the glass support, followed by conventional self-assembly of template cations and silica species. Zeolite crystals are therefore in intimate contact with the glass support, featuring micropores in addition to the mesopores. Hence, these zeolite/glass composites exhibit enhanced diffusional properties in comparison with purely microporous zeolite materials. These enhanced mass transport properties allowed improvement of the selectivity toward light olefins in the important n-hexane cracking reaction.

Diels–Alder Reaction between Isoprene and Methyl Acrylate over Different Zeolites: Influence of Pore Topology and Acidity

“…To investigate the influence of the crystal size, we also prepared zeolites (G1 and G2) at neutral pH by the non-conventional fluoride route (see the Supporting Information). [26,42,[50][51][52] Material characterisation XRD (Figures 3 and 4), SEM (Figures 5-7) and EDX analysis (see Table 2) were used to characterise the as-prepared materials. An evaluation of the Brønsted acidity of the different catalysts was performed through H/D isotope exchange according to the method developed by Louis et al [39,40,44,53] (see Table 2 and the Supporting Information).…”

Insights to Achieve a Better Control of Silicon-Aluminum Ratio and ZSM-5 Zeolite Crystal Morphology through the Assistance of Biomass

“…This might be due to dissolution/recrystallization phenomena, involving peculiar self-assembly processes during the crystal growth. Since zeolites are metastable materials, it is possible to shift from one structure to another one [28], or to crystallize in various morphologies by a simple change in the synthesis duration. This phenomenon was already observed for SiC substrate self-reconstruction into zeolites [29,30].…”

Rational Design of Microporous and Mesoporous Solids for Catalysis: From the Molecule to the Reactor

“…[33][34][35] Following this strategy, binderless ZSM-5 coatings were successfully performed on a perfectly defined glass monolith. [36,37] The latter supports already contained giant pores, macro-and mesopores, thus forming a monolith with hierarchical porosity. The knowledge and technology set up by Yun et al enabled the pore sizes and structures to be perfectly tailored, to produce a well-interconnected three-dimensional porous system.…”

“…[19,23,32,61] This synthetic strategy led to the self-assembly of zeolite nanocrystals on the macroscopic host (sacrificial or not), either silicon-containing leaves, [61] SiC, [19,23] or glass supports. [32,36,37] The auto-arrangement of nanocrystals having MFI or RTH topologies at the SiC surface produced either nanofibers, or continuous films. [19] Although previous studies reported the use of covalent linkers, [62,63] proteins, [64,65] or organic acids [66] to guide the assembly of zeolite crystals, the former pre-cited studies have successfully demonstrated that zeolite nanocrystals can, by themselves, build a nanofibrous network or film.…”