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Recently reported groundbreaking discovery of efficient delamination of zeolite MCM-56, producing colloidal suspensions of MWW monolayers dispersed in the liquid phase, created unprecedented possibilities for the synthesis of a zeolite catalyst. Based on this innovation, the concept of using MWW monolayers to prepare silica-supported zeolite nanosheet catalysts suitable for transformations of large organic molecules was explored in this work. A series of silica-MWW preparations was synthesized from colloidal suspensions of the monolayers, using both solid and colloidal silica sources. The synthesized solids were thoroughly characterized with various physicochemical methods and their catalytic performance was tested in alkylation of mesitylene with benzyl alcohol. The obtained results indicate that solids containing MWW layers dispersed on silica show promising catalytic properties. The mixed MWW:silica catalysts synthesized from dispersions of MWW monolayers and liquid silica were found to exhibit high specific catalytic activity (with TOF values of 3.4 × 10−3 to 4.8 × 10−3 s−1), despite the high content of inactive amorphous silica support (40–60%). Materials synthesized from solid fumed and precipitated silicas showed low or negligible overall activity, which could be attributed to the small incorporation of the zeolitic active phase. For one of such materials, a notable high TOF (4.8 × 10−3 s−1) was found. It was found earlier that ethanol is an effective flocculent for zeolite layers by themselves, but in the presence of solid silica its efficiency was reduced.

In this work, adsorption properties of the UiO-66 metal–organic framework were investigated, with particular emphasis on the influence of structural defects. A series of UiO-66 samples were synthesized and characterized using a wide range of experimental techniques. Type I adsorption isotherms for low-temperature adsorption of N2 and Ar showed that micropore volume and specific surface area significantly increase with the number of defects. Adsorption of hexane isomers in UiO-66 was studied by means of quasi-equilibrated temperature-programmed desorption and adsorption (QE-TPDA) experimental and Monte Carlo simulation techniques. QE-TPDA profiles revealed that only defect-free UiO-66 exhibits distinct two adsorption states. This technique also yielded high-quality adsorption isobars that were successfully recreated using Grand-Canonical Monte Carlo molecular simulations, which, however, required refinement of the existing force fields. The calculations demonstrated the detailed mechanism of adsorption and separation of hexane isomers in the UiO-66 structure. The preferred tetrahedral cages provide suitable voids for bulky molecules, which is the reason for unusual “reverse” selectivity of UiO-66 towards di-branched alkanes. Interconnection of the tetrahedral cavities due to missing organic linkers greatly reduces the selectivity of the defected material.

Layered zeolites, especially MWW, have been used to synthesize pillared micro/mesoporous hybrids with the goal to enhance catalytic activity towards larger molecules. The critical preparation step is expansion of the interlayer space by swelling with cationic surfactants at high pH. Recently reported solutions of MWW monolayers, obtained by exfoliation of the zeolite MCM-56, can be used to prepare analogous materials by flocculation (precipitation) with surfactant solutions. This previously unavailable approach is studied in this work with both high pH (0.2 M, pH > 13.3) and lower pH (0.01 M, pH~12) solutions, and resulted in finding conditions for preparation of catalysts that can be more active than pure microporous layers (zeolite) despite large content of unreactive silica pillars. Both the high and low pH conditions afforded similar expanded surfactant-MWW composites, but their behavior differed during pillaring with TEOS. Well-defined expanded interlayer distances indicated by a low angle reflection in XRD above 3 nm d-spacing was observed only with the high alkalinity preparations. An additional benefit was observed with TEOS treatment in the presence of isopropyl alcohol leading to a product showing high catalytic activity in model alkylation reaction (mesitylene with benzyl alcohol) proceeding faster than with the pure zeolite. The products obtained under different conditions were characterized by textural methods, nitrogen adsorption and QE-TPDA, and FT-IR to investigate acid site parameters. Notably, the MCM-56 used in this work was prepared with addition of aniline as the structure-promoting agent and is the second formulation affording exfoliable MWW materials.

MWW type zeolites are characterized by the presence of zeolitic layers of 2.5 nm thickness, containing 10-member ring sinusoidal channels inside and supercavities with 12-member ring openings located on their surfaces. Expansion and pillaring of layered zeolites increase the access to active sites and can enable or facilitate catalytic activity towards larger reactant molecules. This goal is explored in this work reporting the pillaring of layered zeolite MCM-56 with MWW topology by tetraethylorthosilicate (TEOS) treatment with the assistance of isopropanol, aimed at obtaining hierarchical micro-mesoporous systems. MCM-56 (Si/Al = 12) was synthesized with hexamethyleneimine as a structure-directing and aniline as a structure-promoting agent. Hierarchical porous systems were obtained using two different pillaring methods: (1) with TEOS only and (2) with TEOS mixed with isopropanol. The MWW framework was preserved during swelling/pillaring in both methods. Pillared zeolites obtained via alcohol-assisted pillaring possessed unique intermediate micro-mesopores with the size of about 2 nm. IR study revealed a decrease in the concentration of accessible acid centers upon pillaring. However, the fraction of acid sites on the external surface, accessible for adsorption of large molecules, increased by up to 90%. Catalytic activity was evaluated in the Friedel-Crafts alkylation of mesitylene with benzyl alcohol. Pillaring resulted in reduction of the acid site concentrations, but the materials retained high catalytic activity. Pillaring in the presence of alcohol produced increased turnover frequency values based on the concentrations of the external acid sites.

We report a non-MOF crystalline material {[Mn(imH)]2[Mo(CN)8]}n (imH = imidazole) with exceptional water sorption properties and a very large breathing effect accompanied by an outstanding stability and cyclability – properties that are absolutely unique for this class of compounds (Prussian Blue Analogs). Some previously published PBAs indeed show some sorption properties, but their cyclability is extremely limited - usually 1-3 cycles - followed by significant decomposition/amorphization. Our compound can be cycled more than 50 times without any fatigue and the sorption/desorption proceeds through four different crystal phases, which we have fully characterized structurally enabling the complete understanding of the sorption and breathing mechanism in this material - an achievement rarely reported for MOFs or PBAs. The unique structure of {[Mn(imH)]2[Mo(CN)8]}n enables very strong coupling of its exceptional water sorption performance with the magnetic and photomagnetic properties of the framework, e.g. the sorption process can be followed by in-situ EPR spectroscopy with huge changes in the EPR signal intensity depending on the hydration level.

While metal–organic frameworks (MOFs) are at the forefront of cutting-edge porous materials, extraordinary sorption properties can also be observed in Prussian Blue Analogs (PBAs) and related materials comprising extremely short bridging ligands. Herein, we present a bimetallic nonporous cyanide-bridged coordination polymer (CP) {[Mn(imH)]2[Mo(CN)8]}n (1Mn; imH = imidazole) that can efficiently and reversibly capture and release water molecules over tens of cycles without any fatigue despite being based on one of the shortest bridging ligands known – the cyanide. The sorption performance of {[Mn(imH)]2[Mo(CN)8]}n matches or even outperforms MOFs that are typically selected for water harvesting applications with perfect sorption reversibility and very low desorption temperatures. Water sorption in 1Mn is possible due to the breathing effect (accompanied by a dramatic cyanide-framework transformation) occurring in three well-defined steps between four different crystal phases studied structurally by X-ray diffraction structural analysis. Moreover, the capture of H2O by 1Mn switches the EPR signal intensity of the MnII centres, which has been demonstrated by in situ EPR measurements and enables monitoring of the hydration level of 1Mn by EPR. The sorption of water in 1Mn controls also its photomagnetic behavior at the cryogenic regime, thanks to the presence of the [MoIV(CN)8]4− photomagnetic chromophore in the structure. These observations demonstrate the extraordinary sorption potential of cyanide-bridged CPs and the possibility to merge it with the unique physical properties of this class of compounds arising from their bimetallic character (e.g. photomagnetism and long-range magnetic ordering)., A cyanide-bridged coordination polymer {[Mn(imH)]2[Mo(CN)8]}n shows exceptional water sorption properties, very large breathing effect and outstanding stability – properties that are unique for this class of compounds – Prussian blue analogs.

Zeolite monolayers in solution, reported recently for the framework MWW, enable unprecedented synthetic capabilities that include preparation of molecularly intimate mixtures of different zeolite topologies. As a demonstration, MWW-MFI hybrid materials were synthesized by two methods: in-situ crystallization of MFI by adding the template and silica to solutions of MWW monolayers obtained from the zeolite MCM-56, and ex-situ by mixing the solutions of MWW layers with MFI crystals. Catalytic activity of the mixtures was similar to undiluted pure MWW despite high content of siliceous MFI, which was inert. This suggests that pure MWW layers do not provide optimal packing and accessibility of active sites and can be more efficiently utilized in combination with other components. The mixture of MCM-56 and MFI crystals was 50% less active. Practical benefits may be possible by combining frameworks with different types of activity in catalysis and sorption applications. The mixtures were characterized by the standard methods: X-ray powder diffraction, TEM and SEM imaging, gas adsorptions and FTIR, which showed properties of both the MWW and MFI features with high acid activity and porosity.

[EN] Adsorption of n-alkanes from pentane to decane (C5¿C10) in zeolites LTA (ITQ-29 and 5A) and faujasite (FAU, dealuminated high-silica Na-FAU, NaY, and NaX) as well as branched hexane isomers in FAU was investigated by means of experimental quasi-equilibrated temperature-programmed desorption and adsorption (QE-TPDA) and theoretical Monte Carlo molecular simulations. A novel QE-TPDA method of studying porosity provided high-quality desorption¿adsorption profiles and adsorption isobars of hydrocarbons. A unique two-step adsorption of long-chain alkanes in LTA zeolites was observed and explained in detail based on the results of the theoretical calculations. Although adsorption of n-alkanes in FAU is a one-step process, it also does not occur in a uniform manner because of strong lateral interactions at high loadings. We also investigated the influence of cation content on adsorption equilibrium and energetics for the studied adsorbent¿adsorbate systems, finding a nonlinear relation between heat of adsorption and content of cations in FAU. Investigations on packing of the molecules of n-alkanes were also performed, revealing relations between chain length of the probe molecule and sorption capacity of the studied materials., This work was supported by the National Science Centre, Poland, grant no. 2016/21/N/ST5/00868, and from Spanish Ministerio de Economiay Competitividad (CTQ2016-80206P), and by the Andalucia Region (FQM-1851). The authors also thank C3UPO for the HPC support. The authors obtained financial resources as part of financing the doctoral scholarship from the National Science Center, Poland, grant no. 2018/28/T/STS/00274.