Confinement of Supported Metal Catalysts at High Loading in the Mesopore Network of Hierarchical Zeolites, with Access via the Microporous Windows

Abstract

High loading on a porous support is important for preparing high-performance metal catalysts, but the increased loading often results in a loss of dispersion and limited mass transfer. We approached this problem by supporting a large amount of metal or metal oxide on a hierarchically porous zeolite. The supported catalyst formed an embedded network of nanowires along the zeolite mesopores. Although tightly filled in the mesopores, the catalyst was readily accessible through microporous windows at the encasing mesopore walls. Cobalt, nickel, and TiO 2 , supported in this manner, exhibited high catalytic performance in Fischer−Tropsch synthesis, benzene hydrogenation, and furfural-to-γ-valerolactone conversion, respectively.

Hydrogenation Size‐Selective Pt/Hollow Beta Catalysts

“…The encapsulation of metal precursors into microporous materials is not easily achieved butm ethods based on ion exchange have been shown to be successful at relativelyh igh loading. [14][15][16] Encapsulation of Pt NPs in hollow beta single crystalsw as already achievedb yp re-impregnation [13] leading to the formation of rather large Pt particles (between 10 to 50 nm) with very poor dispersion ( % 3%). Despite ar educed diffusion length, such low metal dispersion did not lead to high catalytic activity per mass of metal.The aim of this work is the synthesis of zeolite-based catalyst, with ah ollow morphology and highly dispersed metal NPs encapsulated inside the zeolite micropores (Figure 1c).…”

Encapsulation of Metal Nanoparticle Catalysts Within Mesoporous Zeolites and Their Enhanced Catalytic Performances: A Review

“…Meantime, the thin MFI walls contributed to a high selectivity to branched hydrocarbons in the gasoline range (C 5 -C 11 ). The authors further increased the loading amount of Co within zeolite Beta or MFI nanosponge, resulting in the construction of Co nanowires or networks along the mesoporous nanochannels (Figures 6D,E ); (Han et al, 2018 ). Although the mesopores were blocked by Co nanostructures, the accessibility through microporous windows on the mesopore walls could also ensure a high catalytic activity toward FT synthesis (Figure 6F ).…”

“…Han et al ( 2018 ) and Kim et al ( 2014 ) successfully prepared mesoporous zeolite nanosponge-encapsulated Co NPs as the efficient catalysts for Fischer-Tropsch (FT) synthesis. In the presence of amphiphilic surfactants containing multiquaternary ammoniums, zeolite nanosponge with ultrathin walls, which could be irregularly interconnected into three-dimensional mesoporous networks, had been synthesized.…”

Controllably Confined ZnO on USY Zeolites (USY@ZnO/Al2O3) as Efficient Lewis Acid Catalysts for Baeyer–Villiger Oxidation

“…[8,9] However, few reports have addressed the catalytic application of ZnO supported on zeolites in heterogeneous catalysis. [13] The reduced porosityw ith supportedm etal oxidesl eads to poor mass transportation and inaccessible active sites, which mainly ac-counts for faster catalystd eactivation. [10] To date, av ariety of approaches have been reported to load transition-metal oxideso nto zeolites, such as wet impregnation, deposition precipitation,a nd sol-gel methods.…”

“…Due to the weak interactions between the metal oxide and the support, the poorly controlled particles could easily migrate around the support and cause seriousblockage of the zeolite pores. [13] The reduced porosityw ith supportedm etal oxidesl eads to poor mass transportation and inaccessible active sites, which mainly ac-counts for faster catalystd eactivation. Thus, it is highly desirable to design novel supported metal oxide zeolite materials with as trong interaction between the metal oxide and the zeolite and also with enhanced hierarchicalp orous structures.…”