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Here, we report the synthesis and characterization of hierarchical zeolite materials with MEL, BEA and FAU structures. The synthesis is based on the carbon templating method with an in situ-generated carbon template. Through the decomposition of methane and deposition of coke over nickel nanoparticles supported on silica, a carbon–silica composite is obtained and exploited as a combined carbon template/silica source for the zeolite synthesis. The mesoporous zeolite materials were all prepared by hydrothermal crystallization in alkaline media followed by removal of the carbon template by combustion, which results in zeolite single crystals with intracrystalline pore volumes of up to 0.44 cm3 g−1. The prepared zeolite structures are characterized by XRD, SEM, TEM and N2 physisorption measurements.

Mesoporous titanium silicalite-1 (TS-1) prepared by carbon-templating is significantly more active than conventional TS-1 for the oxidation of pyridine derivatives using aqueous hydrogen peroxide as oxidant. The catalytic activity is increased by the system of mesopores that helps to overcome the configurational diffusion limitations within the microporous catalyst. The use of a carbon-template for generation of secondary porosity is more effective than desilication. The desilicated catalyst is slightly more active than conventional TS-1, probably due to a decrease of the mean diffusion path length. In contrast, carbon-templated mesopores provides an efficient transport throughout the zeolite, thus preventing deactivation due to product confinement. All catalysts were characterised by X-ray powder diffraction, scanning electron microscopy, UV–Vis spectroscopy and nitrogen physisorption. The results indicate that desilication may cause a surface densification of less catalytically active extra-framework Ti species. Carbon-templating is thus a more gentle and effective method for generating secondary porosity. Utilization of carbon-templated mesoporous TS-1 for oxidation of pyridine derivatives represents a new and environmentally friendly method to synthesise N-oxides., We gratefully acknowledge the support of the Danish Council for Independent Research, Grant No. 10-093717 and Grant No. 12-127580. We would also like to thank for support from the Spanish Ministry of Science and Innovation (project CTQ2011-25517), and Unidad de Apoyo from Catalysis Institute (ICP-CSIC).

With the ongoing developments in biomass conversion, the oxidation of bioethanol to acetaldehyde may become a favorable and green alternative to the preparation from ethylene. Here, a simple and effective method to encapsulate gold nanoparticles in zeolite silicalite-1 is reported and their high activity and selectivity for the catalytic gas-phase oxidation of ethanol are demonstrated. The zeolites are modified by a recrystallization process, which creates intraparticle voids and mesopores that facilitate the formation of small and disperse nanoparticles upon simple impregnation. The individual zeolite crystals comprise a broad range of mesopores and contain up to several hundred gold nanoparticles with a diameter of 2-3 nm that are distributed inside the zeolites rather than on the outer surface. The encapsulated nanoparticles have good stability and result in 50 % conversion of ethanol with 98 % selectivity toward acetaldehyde at 200 °C, which (under the given reaction conditions) corresponds to 606 mol acetaldehyde/mol Au hour(-1) .

A novel synthesis procedure for the preparation of the hierarchical zeolite materials with MFI structure based on the carbon templating method with in situ generated carbon template is presented in this study. Through chemical vapour deposition of coke on nickel nanoparticles supported on silica oxide, a carbon-silica composite is obtained and exploited as a combined carbon template/silica source for zeolite synthesis. This approach has several advantages in comparison with conventional carbon templating methods, where relatively complicated preparative strategies involving multistep impregnation procedures and rather expensive chemicals are used. Removal of the carbon template by combustion results in zeolite single crystals with intracrystalline pore volumes between 0.28 and 0.48 cm3/g. The prepared zeolites are characterized by XRD, SEM, TEM and physisorption analysis. The isomerization and cracking of n-octane is chosen as a model test reaction and the mesoporous zeolite catalyst is found to exhibit higher activity than the conventional catalyst.