Michal Mazur

Hierarchical hybrid organic-inorganic materials with tunable textural properties obtained using zeolitic-layered precursor.

Novel layered zeolitic organic-inorganic materials have been synthesized using a two-dimensional zeolite precursor IPC-1P prepared by a top-down approach from zeolite UTL. The formation of porous materials containing organic linkers or polyhedral oligomeric siloxane covalently bonded to zeolite layers in the interlayer space was confirmed by a variety of characterization techniques (N2/Ar sorption analysis, XRD, (29)Si and (13)C NMR, TEM). The organic-inorganic porous hybrids obtained by intercalation with silsesquioxane posessed layered morphology and contained large crystalline domains. The hybrids exhibited mesoporous or hierarchical micro-/mesoporous systems, stable up to 350 °C. Textural properties of the formed zeolitic organic-inorganic materials can be controlled by varying the linker or synthetic conditions over a broad range. Surface areas and pore volumes of synthesized hybrids significantly exceed those for parent zeolite UTL and corresponding swollen material; the amount of micropores increased with increasing rigidity and size of the organic linker in the order biphenyl > phenylene > ethanediyl.

Ru complexes of Hoveyda–Grubbs type immobilized on lamellar zeolites: activity in olefin metathesis reactions

Summary Hoveyda–Grubbs type catalysts with cationic tags on NHC ligands were linker-free immobilized on the surface of lamellar zeolitic supports (MCM-22, MCM-56, MCM-36) and on mesoporous molecular sieves SBA-15. The activity of prepared hybrid catalysts was tested in olefin metathesis reactions: the activity in ring-closing metathesis of citronellene and N,N-diallyltrifluoroacetamide decreased in the order of support MCM-22 ≈ MCM-56 > SBA-15 > MCM-36; the hybrid catalyst based on SBA-15 was found the most active in self-metathesis of methyl oleate. All catalysts were reusable and exhibited low Ru leaching (<1% of Ru content). XPS analysis revealed that during immobilization ion exchange between Hoveyda–Grubbs type catalyst and zeolitic support occurred in the case of Cl− counter anion; in contrast, PF6 − counter anion underwent partial decomposition.

Atomic force microscopy of novel zeolitic materials prepared by top-down synthesis and ADOR mechanism.

Top-down synthesis of 2D materials from a parent 3D zeolite with subsequent post-synthetic modification is an interesting method for synthesis of new materials. Assembly, disassembly, organisation, reassembly (ADOR) processes towards novel materials based on the zeolite UTL are now established. Herein, we present the first study of these materials by atomic force microscopy (AFM). AFM was used to monitor the ADOR process through observation of the changes in crystal surface and step height of the products. UTL surfaces were generally complex and contained grain boundaries and low-angle intergrowths, in addition to regular terraces. Hydrolysis of UTL to IPC-1P did not have adverse effects on the surfaces as compared to UTL. The layers remained intact after intercalation and calcination forming novel materials IPC-2 and IPC-4. Measured step heights gave good correlation with the X-ray diffraction determined d200 -spacing in these materials. However, swelling gave rise to significant changes to the surface topography, with significantly less regular terrace shapes. The pillared material yielded the roughest surface with ill-defined surface features. The results support a mechanism for the majority of these materials in which the UTL layers remain intact during the ADOR process as opposed to dissolving and recrystallising during each step.

Pressure-induced chemistry for the 2D to 3D transformation of zeolites

ADOR, an unconventional synthesis strategy based on a four-step mechanism: assembly, disassembly, organization, and reassembly, has opened new possibilities in zeolite chemistry. The ADOR approach led to the discovery of the IPC family of materials with tuneable porosity. Here we present the first pressure-induced ADOR transformation of 2D zeolite precursor IPC-1P into fully crystalline 3D zeolite IPC-2 (OKO topology) using a Walker-type multianvil apparatus under a pressure of 1 GPa at 200 °C. Surprisingly, the high-pressure material is of lower density (higher porosity) than the product obtained from simply calcining the IPC-1P precursor at high temperature, which produces IPC-4 (PCR topology). The sample was characterized by PXRD, 29Si MAS NMR, SEM, and HRTEM. Theoretical calculations suggest that high pressure can lead to the preparation of other ADOR zeolites that have not yet been prepared.

Monitoring the assembly–disassembly–organisation–reassembly process of germanosilicate UTL through in situ pair distribution function analysis

A study into the disassembly and organisation steps of the ADOR process has been undertaken through in situ Pair Distribution Function (PDF) analysis. Three aqueous systems (water, 6 M HCl and 12 M HCl) were introduced to a parent zeolite germanosilicate UTL in a cell. Hydrolysis could be clearly seen when UTL was exposed to water over a period of 8 h, forming the disorder layered material, IPC-1P. In hydrochloric acid, the hydrolysis step is too quick to observe and a Ge–Cl containing species could be seen. In 6 M HCl, the rearrangement of the interlayer region began after an induction period of 8 h, with the process still occurring after 15 h. In 12 M HCl, the rearrangement appears to have come to an end after only 6 h.

Zeolite framework functionalisation by tuneable incorporation of various metals into the IPC-2 zeolite

The incorporation of various metals into the zeolite framework creates opportunities for novel applications, especially in catalysis. The recently developed assembly-disassembly-organisation-reassembly (ADOR) strategy was used to prepare zeolites with IPC-2 (OKO) topology. The layered zeolite precursor (IPC-1P) was modified by incorporating various metals (Al, Zn, Sn, Zr, V, Fe, Hf, and Ti) using a stabilisation process. The resulting materials were characterised by X-ray powder diffraction (XRD), Ar adsorption, scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), and diffuse reflectance UV-Vis spectroscopy (DR-UV-Vis). The acidity of Al-containing IPC-2 materials was assessed by acetonitrile and pyridine sorption followed by FT-IR spectroscopy, showing overall concentrations of acid sites of 0.863 mmol g−1 (acetonitrile) and 0.413 mmol g−1 (pyridine). Titanium containing IPC-2 was examined by selective oxidation of methylphenyl sulfide (MPS) to the corresponding sulfoxide (MPSO). Ti-IPC-2 provided a higher conversion than TS-1 after 60 min (30% and 18% respectively) and showed higher selectivity towards MPSO (77% and 63% respectively). Sn-IPC-2 was tested by Baeyer–Villiger oxidation of norcamphor with aqueous hydrogen peroxide, showing a 3.8% norcamphor conversion and a 1.3% yield of the desired lactone (after 8 h reaction). Therefore, the results reported herein clearly show the successful incorporation of metals into the IPC-2 zeolite framework.