0000000001305972
AUTHOR
Bernd Marler
showing 13 related works from this author
Direct Synthesis of Aluminosilicate IWR Zeolite from a Strong Interaction between Zeolite Framework and Organic Template.
2019
A large amount of zeolite structures are still not synthetically available or not available in the form of aluminosilicate currently. Despite significant progress in the development of predictive concepts for zeolite synthesis, accessing some of these new materials is still challenging. One example is the IWR structure as well. Despite successful synthesis of Ge-based IWR zeolites, direct synthesis of aluminosilicate IWR zeolite is still not successful. In this report we show how a suitable organic structure directing agent (OSDA), through modeling of an OSDA/zeolite cage interaction, could access directly the aluminum-containing IWR structure (denoted as COE-6), which might allow access to…
Ab initio structure determination and quantitative disorder analysis on nanoparticles by electron diffraction tomography.
2017
Nanoscaled porous materials such as zeolites have attracted substantial attention in industry due to their catalytic activity, and their performance in sorption and separation processes. In order to understand the properties of such materials, current research focuses increasingly on the determination of structural features beyond the averaged crystal structure. Small particle sizes, various types of disorder and intergrown structures render the description of structures at atomic level by standard crystallographic methods difficult. This paper reports the characterization of a strongly disordered zeolite structure, using a combination of electron exit-wave reconstruction, automated diffrac…
Recent advances in the preparation of zeolites for the selective catalytic reduction of NOx in diesel engines
2019
Metal-exchanged zeolites with small pore sizes have attracted much attention in recent years due to their application in the selective catalytic reduction (SCR) of NOx in diesel engines. Typically, copper-chabazite (e.g. Cu-SSZ-13) has been gradually used as an SCR catalyst in heavy-duty diesel vehicles over the last decade due to its relatively excellent catalytic performance and stability. However, most SSZ-13 zeolites are still prepared via the traditional hydrothermal process in the presence of organic templates, requiring consecutive solid separation and thermal treatment steps to achieve the final zeolite products. In recent years, several strategies for the environmentally friendly p…
The effect of trivalent framework heteroatoms in Cu-CHA on the Selective Catalytic Reduction of NO
2021
Abstract The effect of the trivalent framework atoms (Si4+/M3+ = 13-105) in Cu exchanged CHA-type zeolites was investigated for the selective catalytic reduction of NO with NH3. While the increased hydrophobicity of B-CHA compared to Al-CHA could make it a good candidate for low temperature SCR, the material was too unstable under reaction conditions and the exchanged Cu2+ did not remain isolated. Consequently a lower activity and selectivity than for Al-CHA were observed. Ga-CHA on the other hand showed a similar Cu2+ speciation as Al-CHA at similar Si4+/M3+ ratios. The difference in catalytic activity was remarkably small. While Ga-CHA was less stable upon hydrothermal aging, this was mar…
Transformation synthesis of aluminosilicate SSZ-39 zeolite from ZSM-5 and beta zeolite
2019
Aluminosilicate SSZ-39 zeolite has been successfully prepared by transformation from ZSM-5 and beta zeolite in the presence of N,N-diethyl-cis-2,6-dimethylpiperidinium hydroxide (DMPOH) under hydrothermal conditions. Catalytic tests in the selective catalytic reduction of NOx with NH3 (NH3-SCR) show that the copper-exchanged products synthesized from the interzeolite transformation exhibit excellent catalytic performance.
A Cationic Oligomer as an Organic Template for Direct Synthesis of Aluminosilicate ITH Zeolite
2020
There are a large number of zeolites, such as ITH, that cannot be prepared in the aluminosilicate form. Now, the successful synthesis of aluminosilicate ITH zeolite using a simple cationic oligomer as an organic template is presented. Key to the success is that the cationic oligomer has a strong complexation ability with aluminum species combined with a structural directing ability for the ITH structure similar to that of the conventional organic template. The aluminosilicate ITH zeolite has very high crystallinity, nanosheet-like crystal morphology, large surface area, fully four-coordinated Al species, and abundant acidic sites. Methanol-to-propylene (MTP) tests reveal that the Al-ITH zeo…
The Elusive Structure of Magadiite, Solved by 3D Electron Diffraction and Model Building
2021
In addition to a great swelling ability, layered silicates also allow the functionalization of their interlayer region to form various robust green materials that are used as CO2 adsorbents, drug c...
Efficient and rapid transformation of high silica CHA zeolite from FAU zeolite in the absence of water
2017
High silica CHA zeolite plays an important role in selective catalytic reduction of NOx with NH3 (NH3-SCR), but its synthesis is not highly efficient due to the use of a relatively high-cost structural directing agent (SDA) N,N,N-trimethyl-adamantammonium hydroxide (TMAdaOH) and relatively long crystallization time under hydrothermal conditions. Herein, we report an efficient and rapid synthesis of a high silica CHA zeolite possessing good crystallinity and uniform crystals (CHA-ST). The method includes interzeolite transformation of high silica FAU zeolite in the absence of water but the presence of zeolite seeds and a bromide form of the SDA. The absence of water in the synthesis signific…
Cu-Exchanged CHA-Type Zeolite from Organic Template-Free Synthesis: An Effective Catalyst for NH3-SCR
2020
A Cu-containing CHA-type zeolite was prepared via aqueous ion exchange of the CHA zeolite from organic template-free synthesis. The thus-obtained template-free Cu-CHA showed the best catalytic perf...
Two new members of the Silica-X family of materials: RUB-5, a silica zeolite with a very high framework density and RUB-6, a hydrous layer silicate
2020
Abstract The new zeolite RUB-5 and the new phyllo silicate RUB-6 were synthesized at temperatures between 130 °C and 200 °C from reaction mixtures consisting of SiO2/LiOH/B(OH)3/OA/H2O or SiO2/KOH/OA/H2O (OA = organic additive). Physico-chemical characterization using solid-state NMR spectroscopy, SEM, TG-DTA, and ATR-FTIR spectroscopy confirmed that RUB-5 is a framework silicate while RUB-6 is a layer silicate. The XRD powder patterns were indexed in monoclinic symmetry (space group: C2) with lattice parameters of a0 = 10.2699 (4) A, b0 = 10.6556 (4) A, c0 = 18.1551 (7) A and β = 106.35 (1)° (RUB-5), and a0 = 10.1100 (43) A, b0 = 10.6956 (51) A, c0 = 20.5448 (44) A and β = 105.79 (1)° (RUB…
New zeolite-like RUB-5 and its related hydrous layer silicate RUB-6 structurally characterized by electron microscopy.
2020
RUB-5 and its related hydrous layer silicate RUB-6 were synthesized in the 1990s, but so far their structures have remained unknown due to their low crystallinity and disorder. The combination of 3D electron diffraction, X-ray powder diffraction, high-resolution transmission electron microscopy, structural modelling and diffraction simulations has enabled a comprehensive description of these two nanomaterials, revealng a new framework topology and a unique silica polymorph.
CSD 1995979: Experimental Crystal Structure Determination
2020
Related Article: Yaşar Krysiak, Bernd Marler, Bastian Barton, Sergi Plana-Ruiz, Hermann Gies, Reinhard B. Neder, Ute Kolb|2020|IUCrJ|7|522|doi:10.1107/s2052252520003991
CCDC 1991689: Experimental Crystal Structure Determination
2020
Related Article: Yaşar Krysiak, Bernd Marler, Bastian Barton, Sergi Plana-Ruiz, Hermann Gies, Reinhard B. Neder, Ute Kolb|2020|IUCrJ|7|522|doi:10.1107/s2052252520003991