Tobias Weissenberger

• Dr.-Ing.
• Researcher at Fraunhofer IMM

Hydrothermal synthesis is the state-of-the-art technique for the preparation of zeolites and related porous solids. However, when it comes to the preparation of nanosized zeolites, this technique is limited by low yields, separation problems and high amounts of waste. In this work, we utilized the strengths of a combination of spray drying and stea...

We report a new one‐pot synthesis procedure for hierarchical zeolites with intracrystalline macropores and metal particles encapsulated within the zeolitic walls. The synthesis allows to prepare macroporous zeolites of MFI topology with different heteroatoms (silicalite‐1, ZSM‐5 and TS‐1) and different encapsulated noble metal particles, such as go...

The active sites of catalysts can be tuned by using appropriate organic moieties. Here, we describe a facile approach to synthesise gold nanoparticles (AuNPs) using various Au(I) precursors. The core size of these AuNPs can be precisely tailored by varying the steric hindrance imposed by bound ligands. An interesting relationship is deduced that co...

Designing a stable and selective catalyst with high H2 utilisation is of pivotal importance for the direct gas‐phase epoxidation of propylene. This work describes a facile one‐pot methodology to synthesise ligand‐stabilised sub‐nanometre gold clusters immobilised onto a zeolitic support (TS‐1) to engineer a stable Au/TS‐1 catalyst. A non‐thermal O2...

Designing a stable and selective catalyst with high H 2 utilisation is of pivotal importance for the direct gas-phase epoxidation of propylene. This work describes a facile one-pot methodology to synthesise ligand-stabilised sub-nanometre gold clusters immobilised onto a zeolitic support (TS-1) to engineer a stable Au/TS-1 catalyst. A non-thermal O...

A one‐pot synthesis of aluminium‐containing mesoporous silica particles (Al‐MSPs) utilizing polyvinyl alcohol (PVA) as steric stabilization agent is reported. PVA prevents particle agglomeration even when the ionic aluminium source is present in the synthesis mixture. Silicon and aluminium sources were utilised completely, resulting in high yield a...

Hierarchical pore structures exhibit features on several length scales governing important materials properties. Correlative 360° electron tomography and lab‐based Nano‐CT allowing for scale‐bridging 3D analyses of volumes of (60 μm)³ with nm‐resolution were applied to macroporous zeolite particles. More details can be found in article number 20011...

Introducing broad pores could decrease diffusion limitations in zeolite catalysis – but what is the optimal structure? In article number 2001409 by Marc‐Olivier Coppens, Guanghua Ye, and co‐workers, a systematic, optimal design methodology is discussed. It borrows lessons from nature to guide hierarchically structured zeolite synthesis, aided by mu...

Hierarchically structured zeolites can mitigate problems arising from the slow transport in the micropores, such as diffusion limitations. Hence, a manifold of different preparation methods for hierarchical zeolites have been developed over the years and the corresponding zeolites showed superior performance due to enhanced mass transport caused by...

Zeolite catalysis is often affected by transport limitations, which significantly influence overall performance. Introducing wide pores as molecular transport highways can reduce transport limitations, control the product distribution, and mitigate effects of catalyst deactivation. Nevertheless, the importance to rationally design the meso‐ and mac...

Hierarchical pore structures exhibit morphological features on several length scales, which govern important materials properties in catalysis, such as catalytic activity, diffusivity or selectivity. Correlative tomography offers unique opportunities for a comprehensive and scale-bridging 3D characterization of such complex pore morphologies, which...

We present the effect of different combinations of intracrystalline pore systems in hierarchical ZSM‐5 zeolites on their performance as MTO catalysts. We prepared ZSM‐5 zeolites with additional intracrystalline mesoporous, intracrystalline macropores and a novel ZSM‐5 type zeolite with intracrystalline meso and macropores. The catalytic results sho...

The creation of intergrown layer-like zeolite crystals is one route to form hierarchical zeolites. Faujasite-type (FAU-type) zeolites are among the industrially most important zeolites and the implementation of hierarchical porosity is a promising way to optimise their catalytic and adsorptive performance. After a short general survey into routes f...

The successful synthesis of hierarchically structured titanium silicalite‐1 (TS‐1) with large intracrystalline macropores by steam‐assisted crystallisation of mesoporous silica particles is reported. The macropore topology was imaged in 3D by using electron tomography and synchrotron radiation‐based ptychographic X‐ray computed tomography, revealin...

Three-dimensional (3D) x-ray microscopy by ptychographic tomography requires elaborate numerical reconstructions. We describe a coupled ptychography-tomography reconstruction algorithm and apply it to an experimental ptychographic x-ray computed tomography data set of a catalyst particle. Compared to the traditional sequential algorithm, in which p...

Scale-Bridging 3D Analysis of Micro-/Macroporous Zeolite Particles Using X-Ray Nano-Tomography and Electron Tomography - Volume 25 Supplement - Benjamin Apeleo Zubiri, Tobias Weissenberger, Thomas Przybilla, Janis Wirth, Silvan Englisch, Dominik Drobek, Wilhelm Schwieger, Erdmann Spiecker

Hierarchically structured ZSM-5 catalysts have been prepared using different sized mesoporous silica particles as sacrificial template, resulting in zeolite crystals with different sized intracrystalline macropores but very similar zeolitic charactacter such as crystallinity, chemical composition, acidic and textural properties. This set of catalys...

Campholenic aldehyde is highly valuable fine chemical that can be obtained by multistep synthesis from monoterpene α-pinene isolated from turpentine oil. Therefore, economical and environmentally benign synthesis of this aldehyde is within the high interest. In this study, different titanosilicates were prepared and tested in selective campholenic...

A new synthesis route for the zeolitic imidazolate framework ZIF-4 is reported. About 200 g of ZIF-4 are prepared by sonothermal synthesis from ZnO at room temperature. The ZIF-4 prepared by sonothermal synthesis is comparable to the ZIF-4 synthesized by the pathway reported in literature with respect to the powder X-ray diffraction pattern, partic...

'Hierarchy' is a property which can be attributed to a manifold of different immaterial systems, such as ideas, items and organisations or material ones like biological systems within living organisms or artificial, man-made constructions. The property 'hierarchy' is mainly characterised by a certain ordering of individual elements relative to each...

Hierarchically organized systems are commonly encountered in the natural environment. Such hierarchical systems are related mostly to structural properties or fluid dynamic properties. Currently, macropores are being introduced in zeolites through sphere templating, postsynthetic modifications, and templating with macroporous supports. Among these...