Hierarchical mesoporous TS-1 zeolite: a highly active and extraordinarily stable catalyst for the selective oxidation of 2,3,6-trimethylphenol

Abstract

We report the synthesis of a new hierarchical mesoporous TS-1 type zeolite by a simple steam-assisted crystallization method. This novel product exhibits high catalytic activity and a strongly prolonged lifetime in the selective oxidation of 2,3,6-trimethylphenol to trimethyl-p-benzoquinone.

Desilication of TS-1 zeolite for the oxidation of bulky molecules

“…As previously reported [9][10][11][12][13][14][15][16][17][18][19], silicon is preferentially extracted into solution upon alkaline treatment while Al in ZSM-5 or Ti in the case of TS-1 remains in the solid. Along this manuscript, we address the effect of different alkaline treatments on the physical properties (porosity and crystallinity) and the catalytic behavior of desilicated TS-1 zeolites in the oxidation of small and bulky molecules.…”

“…4 shows the UV-vis spectra of the parent TS-1 and the desilicated samples. Catalytic activity of titanium-containing materials is related to the coordination of the Ti active sites and, more specifically, to the tetrahedrally coordinated Ti(IV) sites, which can be easily analyzed by UV-vis spectroscopy [16,[20][21][22]. The parent zeolite shows a band centered at 210-220 nm, which corresponds to isolated tetrahedrally coordinated Ti species, together with a broad shoulder between 250-290 nm associated with highly coordinated (oligomeric) Ti [6,[20][21][22].…”

“…In order to minimize diffusional limitations in the microporous network of MFI zeolites, several approaches have been developed in the last few years to induce intra-crystalline mesoporosity including hard templating [4][5][6], soft templating [7,8], demetalation [9][10][11][12][13][14][15] and modified crystallization methods [16,17]. Unfortunately, several of these approaches provide structures which are not hydrothermally stable in a manner similar to nanocrystalline zeolites.…”

Multimodal Zr-Silicalite-1 zeolite nanocrystal aggregates with interconnected hierarchically micro-meso-macroporous architecture and enhanced mass transport property

“…There have been many successful approaches to hierarchical MFI-type zeolites [16]. The synthetic techniques involve (i) chemical and/or physical posttreatment, such as the steaming or acid leaching methods [17][18][19]; (ii) hard templating synthesis, such as carbon and colloid templating [20][21][22]; (iii) soft templating synthesis, such as the use of amphiphilic organosilanes [23,24]. However, for increased efficiency within industrial processes, hierarchically porous zeolitic catalysts displaying both micro-meso-macroporosity and strongly active sites are more desirable.…”

Well‐Organized Zeolite Nanocrystal Aggregates with Interconnected Hierarchically Micro–Meso–Macropore Systems Showing Enhanced Catalytic Performance

“…Recently, various successful attempts to synthesize mesoporous or macroporous zeolites with bimodal porosity and framework acidity have been reported. [4][5][6][7][8][9][10][11][12][13][14][15] These materials hold great promise, particularly in catalysis and separation processes in which optimization of the diffusion and confinement regimes is required. Whereas micro-and/or mesopores provide size and shape selectivity for the guest molecules, and thus enhance the host-guest interactions, the presence of macropores can considerably favor diffusion of the guest molecules and thus their access to the active sites.…”