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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.

The rapidly rising level of carbon dioxide in the atmosphere resulting from human activity is one of the greatest environmental problems facing our civilization today. Most technologies are not yet sufficiently developed to move existing infrastructure to cleaner alternatives. Therefore, techniques for capturing carbon dioxide from emission sources may play a key role at the moment. The structure of the UiO‐66 material not only meets the requirement of high stability in contact with water vapor but through the water pre‐adsorbed in the pores, the selectivity of carbon dioxide adsorption is increased. We successfully applied the recently developed methodology for water adsorption modelling. It allowed to elucidate the influence of water on CO2 adsorption and study the mechanism of this effect. We showed that water is adsorbed in octahedral cage and stands for promotor for CO2 adsorption in less favorable space than tetrahedral cages. Water plays a role of a mediator of adsorption, what is a general idea of improving affinity of adsorbate. On the basis of pre‐adsorption of methanol as another polar solvent, we have shown that the adsorption sites play a key role here, and not, as previously thought, only the interaction between the solvent and quadrupole carbon dioxide. Overall, we explained the mechanism of increased CO2 adsorption in the presence of water and methanol, as polar solvents, in the UiO‐66 pores for a potential post‐combustion carbon dioxide capture application., MOF trap: We successfully applied a recently developed methodology for water adsorption modelling that allows to elucidate the influence of water on CO2 adsorption and study the mechanism of this effect. We show that water is adsorbed in octahedral cage and stands for promotor for CO2 adsorption in less favorable space than tetrahedral cages. We explain the mechanism of increased CO2 adsorption in the presence of water and methanol, as polar solvents, in the UiO‐66 pores for a potential post‐combustion carbon dioxide capture application.

Heterogeneous catalysis plays an important role in many chemical reactions, especially those applied in industrial processes, and therefore, its theoretical foundations are introduced not only to students majoring in chemical engineering or catalysis but also as part of general chemistry courses. The consideration of catalytic activity of various solids and mechanisms of catalytic reactions requires the introduction of the concept of an active site, which together with the catalyst specific surface area are discussed as key parameters controlling the reaction rate. There are many known demonstrations of heterogeneous catalysis phenomena that can be performed live in a lecture hall, but all of them focus only on the general idea of catalytic processes and are not suitable for quantitative analysis. Therefore, herein we present a simple demonstration of the influence of the specific surface area of a catalyst on the rate of a catalytic reaction. This demonstration is based on a model reaction of hydrogen peroxide decomposition catalyzed by cobalt spinel (Co3O4) calcined at various temperatures. The differences in reaction rates can be monitored visually, and the obtained data can be used directly for a simple kinetic analysis, including comparison of numerical values of the reaction rate constants.

Discrete molecular species that can perform certain functions in response to multiple external stimuli constitute a special class of multifunctional molecular materials called smart molecules. Herein, cyanido-bridged coordination clusters {[FeII (2-pyrpy)2 ]4 [MIV (CN)8 ]2 }⋅4 MeOH⋅6 H2 O (M=Mo (1 solv), M=W (2 solv) and 2-pyrpy=2-(1-pyrazolyl)pyridine are presented, which show persistent solvent driven single-crystal-to-single-crystal transformations upon sorption/desorption of water and methanol molecules. Three full desolvation-resolvation cycles with the concomitant change of the host molecules do not damage the single crystals. More importantly, the Fe4 M2 molecules constitute a unique example where the presence of the guests directly affects the pressure-induced thermal spin crossover (SCO) phenomenon occurring at the FeII centres. The hydrated phases show a partial SCO with approximately two out-of-four FeII centres undergoing a gradual thermal SCO at 1 GPa, while in the anhydrous form the pressure-induced SCO effect is almost quenched with only 15 % of the FeII centres undergoing high-spin to low-spin transition at 1 GPa.

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.

This article demonstrates preparation of metal functionalized zeolite catalysts via a new homogeneous solution pathway enabled by the recently reported exfoliation of zeolite MWW into solution of unilamellar nanosheets. The preparation is carried out by mixing solutions of exfoliated MWW monolayers and Pt nanoparticles with initial size of ca 3 nm and isolation of such hybrid catalysts by freeze-drying. Optionally, the MWW layer solutions were purified by dialysis prior to mixing with the metal solution, which turned out to be beneficial for quality and textural characteristics. However, catalytic performance in the model reaction – 3-nitrotoluene hydrogenation, was mostly determined by the Pt level, i.e. at least 0.3%, and less affected by the apparent quality of the final zeolite support. The catalysts revealed agglomeration of the Pt nanoparticles from roughly 3 nm to between 5 and 10 nm.

We combine experiments and simulations to study the adsorption of water in several UiO-66 frameworks (ideal and defect-containing structures). We propose a new set of charges for the frameworks that accurately provides the water-structure interaction at the molecular level. The new set is suitable for predicting water adsorption in the ideal UiO-66 structure, providing for the first time, good agreement between experimental and calculated isotherms. The proposed procedure for tuning the point charges of the framework to achieve agreement with experiments is universal and can easily be extended to other MOFs. We explore the structural characteristics in terms of adsorption of water and the potential application of these materials to water harvesting from air. Our results show that the number of introduced defects significantly affect water sorption properties, which results in shifting steep water uptake and increasing saturation loading. Additional performed experiments, such as Ar sorption and the use of the QE-TPDA method allow for a broad characterization of structure-containing defects and the impact that these defects exert on the properties of the materials.

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.

Due to its exceptional chemical and thermal stability, ZIF-8 is one of the most promising representatives of nanoporous metal-organic frameworks. In this work, we investigate adsorption properties of this material both experimentally and theoretically. The experiments were carried out on 8 preparations differing in morphology of the crystals. Adsorption was studied in isothermal approach exploiting standard adsorbates, such as N2 or CO2, as well as in isobaric regime with C5–C9 linear alkanes. The latter were performed with the novel quasi-equilibrated temperature-programmed desorption and adsorption (QE-TPDA) technique showing that a complexity of n-alkanes adsorption mechanism in ZIF-8 depends on the nature of adsorbate. Unexpectedly, for adsorption of C7–C9 n-alkanes a two-step process was found. QE-TPDA yielded high quality adsorption isobars which were successfully reproduced by Grand-Canonical Monte Carlo molecular simulations. The calculations showed that the specific adsorption behaviour of ZIF-8 is due to the fact that its structure undergoes conformational changes in order to adapt to the guest molecules. QE-TPDA measurements with n-nonane were performed at conditions close to saturation of the adsorbate. This allowed to observe surface-related adsorption on the ZIF-8 crystals, which was correlated with their size.

A new microporous cadmium metal-organic framework was synthesized both mechanochemically and in solution by using a sulfonyl-functionalized dicarboxylate linker and an acylhydrazone colinker. The three-dimensional framework is highly stable upon heating to 300 °C as well as in aqueous solutions at elevated temperatures or acidic conditions. The thermally activated material exhibits steep water vapor uptake at low relative pressures at 298 K and excellent recyclability up to 260 °C as confirmed by both quasi-equilibrated temperature-programmed desorption and adsorption (QE-TPDA) method as well as adsorption isotherm measurements. Reversible isotherms and hysteretic isobars recorded for the desorption-adsorption cycles indicate the maximum uptake of 0.19 g/g (at 298 K, up to p/p0 = 1) or 0.18 g/g (at 1 bar, within 295-375 K range), respectively. The experimental isosteric heat of adsorption (48.9 kJ/mol) indicates noncoordinative interactions of water molecules with the framework. Exchange of the solvent molecules in the as-made material with water, performed in the single-crystal to single-crystal manner, allows direct comparison of both X-ray crystal structures. The single-crystal X-ray diffraction for the water-loaded framework demonstrates the orientation of water clusters in the framework cavities and reveals their strong hydrogen bonding with sulfonyl, acyl, and carboxylate groups of the two linkers. The grand canonical Monte Carlo (GCMC) simulations of H2O adsorption corroborate the experimental findings and reveal preferable locations of guest molecules in the framework voids at various pressures. Additionally, both experimental and GCMC simulation insights into the adsorption of CO2 (at 195 K) on the activated framework are presented.

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.

Adsorption of hexane isomers in high silica MFI and MEL zeolites was studied by means of quasi-equilibrated temperature-programmed desorption and adsorption and Monte Carlo simulations. Configurational bias and continuous fractional component Monte Carlo were applied for these systems, and their efficiency and effectiveness were compared. All branched hexane isomers, i.e., 2-methylpentane, 3-methylpentane, 2,3-dimethylbutane, and 2,2-dimethylbutane, were used. The agreement between experimental and calculated adsorption isobars confirmed that quasi-equilibrated temperature-programmed desorption and adsorption is an effective method for studying adsorption of branched alkanes in zeolites. Detailed literature review on adsorption of branched paraffins in MFI revealed diffusion limitations which make reaching adsorption equilibria of these molecules difficult with isothermal approach at low temperatures. Temperature-dependent measurements conducted in this work largely allowed avoiding such limitations. Adso...

[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.

This report focused on setting up general experimental protocols for n-alkanes thermoporosimetry (TPM) in application for the study of porosity in a series of mesoporous SBA-15 silicas. The results were referred to the porosity characteristics obtained from nitrogen adsorption/desorption at −196 °C and quasi-equilibrated temperature programmed desorption and adsorption (QE-TPDA) of nonane. n-Hexane, n-heptane and n-octane were used as liquid probes in TPM experiments. For the first time the role of heating and cooling rate and liquid to solid mass ratio in n-alkane-TPM measurements was evaluated. n-Heptane was found to be the most appropriate n-alkane probe, n-octane admissible one, and n-hexane unsuitable due to the strong dependence of the DSC effects on choice of experimental conditions. Empirical calibration equations for n-heptane and n-octane thermoporosimetry were established.

Mesoporous SBA-15 materials with unmodified surface and different pore sizes between 4.4 and 7.1 nm were examined as carriers of ciprofloxacin, a class IV BCS drug with low aqueous solubility and permeability, to increase its bioavailability. The highest ciprofloxacin loading, 18% wt., was observed with the SBA-15 with the intermediate pore size, 6.7 nm. Release profiles of the drug to the aqueous media showed that in all cases solubility of the drug was significantly increased (more than 10-fold improvement). Such enhancement in the solubility of ciprofloxacin can be explained on the basis of favorable particle chemical formula in the composite, with protonated carboxylic group, in an addition to the drug amorphization, as suggested by the XRD profiles. SBA-15 with the largest pores and intermediate ciprofloxacin content (13%) showed the slowest release rate, suggesting that type of interaction between adsorbed drug and the carrier is the most important factor governing the release rate. Toxicity and viability tests were carried out and showed that unmodified SBA-15 at moderate concentrations can be used as a safe carrier, not influencing the proliferation and metabolic activity of the cells.

Adsorption of cyclohexane in pure silica zeolites was studied experimentally and by molecular simulations. Based on the adsorption isobars obtained from the quasi-equilibrated temperature adsorption and desorption (QE-TPDA) measurements and reported adsorption isotherms for high-silica zeolites Y, ZSM-5, and ZSM-11 we refined Lennard-Jones parameters for guest-host interactions available in the literature. Adsorption of cyclohexane from equimolar mixture of twisted-boat and chair conformations has been screened in 171 pure silica zeolitic structures using grand canonical Monte Carlo simulations. Almost 20 frameworks showing extraordinary preference for adsorption of the chair conformation over the twisted boat one or vice versa were found. This selectivity was attributed to the geometry of channels and cavities present in the pore structures, as all t-boat selective structures possess channels or cavities of 8.3-9.1 A. We also differentiated ways of chair-selectivity depending on the size and shape of the channels or cavities and also on the arrangement of the guest molecules in the pores.

The catalytic activity of novel micro/mesoporous ZSM-5 in the dehydration process of alcohols has been studied with respect to their acidity and porosity. Samples characterized by similar Si/Al ratios in the range between 23 and 36 were chosen to ensure the ability to properly monitor the changes in catalytic performance related to the concentration of acid sites, as well as their accessibility and strength. Special attention has been paid to porosity studies involving low-temperature nitrogen sorption and the quasi-equilibrated temperature programmed desorption of hydrocarbons. Thus, the wide range of materials from typically microporous ZSM-5 to micro/mesoporous analogues obtained by different methods, but presenting many similar properties, allowed us to investigate the influence of porosity character on catalytic performance. Both the acidity and porosity properties, which were significantly perturbed by various synthesis and modification strategies, were clearly reflected in the catalytic performance of hierarchical zeolites, described as volcano curve dependence.

Adsorption of polar and nonpolar molecules in hydrophilic–hydrophobic STAM-1 metal–organic framework was studied by means of quasi-equilibrated temperature-programmed desorption and adsorption (QE-TPDA) experimental technique and molecular simulation. The QE-TPDA measurements revealed that thermal stability of the studied material in the presence of water may be lower than determined from thermogravimetric analysis. Molecular dynamics showed evident impact of diffusion on the adsorption mechanism in STAM-1. The QE-TPDA profiles recorded for adsorption of n-alkanes, water, and alcohols indicate the gate-opening effect occurring only upon adsorption of polar molecules, which was confirmed by in situ IR spectroscopy. Monte Carlo molecular simulations agree with experimental data revealing preferable adsorption sites for the molecules of alcohols in STAM-1. Simulations also showed that the molecular mechanism of the gate-opening is dependent on the size of polar guest molecules.

Layered zeolite materials with FER layer topology can produce various condensed and expanded structures including zeolite frameworks, FER and CDO, their interlayer expanded forms (IEZ), and organic-intercalated and pillared derivatives. This work concerns pillaring of the surfactant-swollen derivative with a gallery height of ca. 2.5 nm between layers by treatment with tetraethylorthosilicate (TEOS) at room and elevated temperatures. The materials obtained at 100 °C and higher showed unusual properties including 2 nm pores on the micro/mesoporous border and disordered layer packing indicated by the absence of distinct low angle interlayer peaks at d-spacing >3 nm (~3° 2¿ Cu Ka radiation) in the X-ray diffraction pattern (XRD). TEOS treatment at room temperature produced a pillared molecular sieve with the expected mesoporous characteristics, namely a pore size of around 3 nm and a high intensity low angle (001) peak at 2.3° 2¿, and a d-spacing of 3.8 nm, in the XRD. The characterization aiming to elucidate the nature of the obtained unusual products included gas adsorption isotherms, aberration corrected (Cs-corrected) Scanning Transmission Electron Microscopy (STEM) studies and 29Si solid state NMR. BET surface area values decreased with the temperature of TEOS treatment from approximately 1200 m2 g-1 to ~900 and 600 m2 g-1, at room temperature, 100 °C, and 120 °C, respectively. The 29Si solid state NMR revealed the presence of both Q3 ((SiO)3SiOX, X = H or minus charge) and Q4 ((SiO)4Si) centers giving separated signals up to the pillaring step. After pillaring at 100 °C and calcination, the nominal intensity ratios Q4:Q3 were 2.17 and 2.61 but the signals were merged into one broad peak indicating the structural heterogeneity of Si-O coordination. The microscopy showed the presence of FER layers in the samples but the overall structure and composition were not well-defined. The observed unusual disorganization and possible partial degradation of layers during pillaring may result from the combination of high temperature, alkalinity (surfactant hydroxide) and siliceous composition of the layers. The obtained pillared products are of interest for the preparation of larger pore catalysts and sorbents or controlled drug delivery.

Layered zeolite precursor MCM-22P can be stabilized as interlayer expanded structure MWW-IEZ with enlarged pores by silylation producing –O–Si(OH)2–O– bridges. It adsorbs two times more cerium than MCM-22 and becomes activated for CO oxidation to CO2 at room temperature. This represents one of the most notable activity enhancements upon modification of layered zeolites.

The catalytic activity of a doubly promoted K/Zn–Co3O4 spinel catalyst in the deN2O reaction was tested for 10 weeks in a nitric acid pilot plant. A charge of 15 kg of the catalyst was synthesized ...

Porosity of zeolites ZSM-5 (Si/Al = 32 or 164) desilicated with NaOH or NaOH/TBAOH (tetrabutylammonium hydroxide) solutions was studied by means of quasi-equilibrated temperature programmed desorption and adsorption (QE-TPDA) of selected hydrocarbons. QE-TPDA of n-nonane confirmed substantial formation of mesopores upon desilication, observed also in N2 adsorption/ desorption isotherms. Very narrow mesopore size distributions with maxima at about 4 nm, typical for partially constricted mesopore networks, were obtained for all desilicated zeolites. It was also observed that desilication with NaOH/TBAOH results in formation of additional slightly larger mesopores (ca. 4-6 nm) while even larger mesopores (6-10 nm) were found after leaching with NaOH only. Thermodesorption of n-hexane revealed that the micropores in the desilicated zeolites remained unchanged. Acidity of the zeolites was characterized by quantitative IR measurements of pyridine and collidine (2,4,6-trimethylpyridine) adsorbed on acid sites. Increased numbers of Brønsted acid sites accessible for large collidine molecules found for the modified zeolites indicate that during desilication redistribution of the framework Al atoms to the surface of mesopores occurred. The influence of TBAOH presence in desilicating mixture on porosity and accessibility of the acid sites was also discussed.

Adsorption of n-alkanes from methane to decane (C1–C10) on AlPO4-5 aluminophosphate was studied by means of Monte Carlo simulations. The additional experimental study with use of quasi-equilibrated temperature-programmed desorption and adsorption (QE-TPDA) yielded high quality adsorption isobars of C5–C10 n-alkanes. The QE-TPDA based isotherms were accurately reproduced in the simulation, thus validating the applied force field. The agreement between experimental and simulated data indicated that the QE-TPDA is a reliable method for studying porosity-related adsorptive properties. The simulations revealed differences in the adsorption mechanism of the n-alkane series, with unmistakable site-based adsorption for short molecules (C1–C5) at saturation. Kinetic properties of the studied systems determined with the use of molecular dynamics exposed chain length dependency of the self-diffusion coefficient, indicating probably a resonant diffusion mechanism.

Many chemical compositions produce layered solids consisting of extended sheets with thickness not greater than a few nanometers. The layers are weakly bonded together in a crystal and can be modified into various nanoarchitectures including porous hierarchical structures. Several classes of 2-dimensional (2D) materials have been extensively studied and developed because of their potential usefulness as catalysts and sorbents. They are discussed in this review with focus on clays, layered transition metal oxides, silicates, layered double hydroxides, metal(iv) phosphates and phosphonates, especially zirconium, and zeolites. Pillaring and delamination are the primary methods for structural modification and pore tailoring. The reported approaches are described and compared for the different classes of materials. The methods of characterization include identification by X-ray diffraction and microscopy, pore size analysis and activity assessment by IR spectroscopy and catalytic testing. The discovery of layered zeolites was a fundamental breakthrough that created unprecedented opportunities because of (i) inherent strong acid sites that make them very active catalytically, (ii) porosity through the layers and (iii) bridging of 2D and 3D structures. Approximately 16 different types of layered zeolite structures and modifications have been identified as distinct forms. It is also expected that many among the over 200 recognized zeolite frameworks can produce layered precursors. Additional advances enabled by 2D zeolites include synthesis of layered materials by design, hierarchical structures obtained by direct synthesis and top-down preparation of layered materials from 3D frameworks.

NO x emissions will need to be controlled from gas engines, which in the future could be using a syngas/producer gas as a fuel (generated from the gasification of biomass). In anticipation of this need, the activity of a copper-exchanged ultrastabilized zeolite Y was investigated, for the selective catalytic reduction of NO x . The catalyst performance and properties were compared with reference samples of Cu-exchanged un-stabilized Y and Cu exchanged ZSM-5 zeolites. Activity was related to the number and nature of active centers, which were determined by in situ FTIR and TPD experiments using CO, NO, and NH 3 as probe molecules. In the test reaction the ultrastabilized Cu-USY catalyst showed high activity at low temperatures and offered high hydrothermal resistance, whilst the Cu-ZSM-5 catalyst demonstrated the highest overall activity. The observed low temperature activity of the ultrastabilized Cu-USY catalyst was linked to the high abundance of Cu + sites, which were detected by in situ FTIR analyses using CO adsorption.

Thermoporosimetry, i.e., DSC measurements of melting point depression of water and heptane confined in mesopores, has been used for determination the pore size distribution of several mesoporous silicas synthesized with the use of micelle templates. Porosity of these materials was additionally characterized by low-temperature nitro- gen adsorption and quasi-equilibrated thermodesorption of nonane. The pore size distributions obtained using the water thermoporosimetry were similar to those determined using the other methods, but the pore size values found for the narrow pore materials were underestimated by ca 1 nm. Too large pore sizes obtained for the wide pore silica from heptane thermoporosimetry were attributed to nonlinear dependence of the melting point depression on the reci- procal of the pore size.

Mesoporous silicas MCM-41 and SBA-15 were studied using the quasi-equilibrated temperature-programmed desorption and adsorption (QE-TPDA) of n-nonane and 1-butanol. The QE-TPDA profiles of n-nonane containing one desorption maximum were typical for the mesoporous materials. The pore size distributions from the thermodesorption data were similar to those calculated from N2 adsorption isotherms. The QE-TPDA profiles of 1-butanol exhibited low temperature maxima (below 70 °C) resulting from desorption of the adsorbate filling the mesopores and high temperature maxima (at ca. 100 °C) attributed to desorption of the molecules specifically adsorbed on the hydrogen-bonded silanols. These findings were confirmed by IR measurements. Hydrothermal treatment of MCM-41 resulted in increase of the H-bonded silanol concentration, while for SBA-15 an inverse effect was observed.

Equilibrated thermodesorption (TPED) and quasi-equilibrated temperature programmed desorption and adsorption (QE-TPDA) were employed as methods for studying the influence of different extraframework cations (Na+, K+, Li+, Cu2+, Zn2+, or Mg2+) on adsorption of n-hexane on ZSM-5 zeolite with high Al content (Si/Al = 15). Considerable influence of the cations on both initial adsorption in the micropores and ordering of the adsorbed molecules, occurring at high coverages, has been observed. This influence is reflected by the values of the adsorption enthalpy and entropy, determined by fitting the dual site Langmuir (DSL) adsorption function to the equilibrated thermodesorption profiles. However, no clear correlation between the determined parameters and properties of the extraframework cations could be found.

Temperature programmed desorption profiles of n -nonane were measured for MCM-41, SBA-15 and HMS mesoporous silicas under quasi-equilibrium conditions using standard TPD setup with a chromatographic detector, utilizing He + 0.4% n -C 9 H 20 mixture as a carrier gas. A method for determination of the pore size distributions according to a modified BJH scheme, based on the Kelvin equation for the fluid core radius and the BET-type function for the adsorbed film thickness, was proposed. The resulting pore size distributions are in good agreement with those obtained by standard BJH analysis of the N 2 desorption isotherms.

Framework-substituted cerium MCM-22 zeolites were synthesized with both TEOS and solid silica sources. The Si/Al ratio in the gel was 15/1 with two different Si/Ce ratios equal to 100/1 and 30/1. The products showed high Bronsted acid site concentrations, above 700 μmol g−1, that diminished slightly as the Ce content increased. The state of Ce was evaluated by IR and UV-vis spectroscopy. There was no indication of a separate Ce phase and extraframework atoms. Both oxidation states, 3+ and 4+, were present. In contrast to the interlayer expanded form MCM-22-IEZ with Ce exchanged into it, the present MCM-22 did not show oxidation of adsorbed CO. This indicates fundamental differences in the location of Ce, which is outside the framework in the exchanged form. The framework-substituted Ce-MCM-22 became active for CO oxidation after its conversion into the IEZ form and additional exchange of Ce. Textural properties were evaluated by nitrogen adsorption and quasi-equilibrated temperature-programmed desorption and adsorption (QE-TPDA) of hydrocarbons.

Many chemical compositions produce layered solids consisting of extended sheets with thickness not greater than a few nanometers. The layers are weakly bonded together in a crystal and can be modified into various nanoarchitectures including porous hierarchical structures. Several classes of 2-dimensional (2D) materials have been extensively studied and developed because of their potential usefulness as catalysts and sorbents. They are discussed in this review with focus on clays, layered transition metal oxides, silicates, layered double hydroxides, metal(iv) phosphates and phosphonates, especially zirconium, and zeolites. Pillaring and delamination are the primary methods for structural modification and pore tailoring. The reported approaches are described and compared for the different classes of materials. The methods of characterization include identification by X-ray diffraction and microscopy, pore size analysis and activity assessment by IR spectroscopy and catalytic testing. The discovery of layered zeolites was a fundamental breakthrough that created unprecedented opportunities because of (i) inherent strong acid sites that make them very active catalytically, (ii) porosity through the layers and (iii) bridging of 2D and 3D structures. Approximately 16 different types of layered zeolite structures and modifications have been identified as distinct forms. It is also expected that many among the over 200 recognized zeolite frameworks can produce layered precursors. Additional advances enabled by 2D zeolites include synthesis of layered materials by design, hierarchical structures obtained by direct synthesis and top-down preparation of layered materials from 3D frameworks.

Functionalization of the mesoporous silica walls by organic species results in formation of porous hybrid materials. Combination of organic and inorganic components leads to the materials whose properties differ considerably from those of their individual, isolated components, especially with respect to their surface chemistry, hydrophilicity/hydrophobicity and/or pore connectivity and size distribution. In this paper a detailed porosity characterization of SBA-15 silica before and after its surface functionalization with (R 2 O) 3 -Si-R 1 -NH 2 molecules is reported. The results obtained from nitrogen sorption were compared to those derived from quasi-equilibrated thermodesorption of n-nonane and from water and n-heptane thermoporosimetry. A small decrease of the pores size and pore volume upon the modification was detected for all amine functionalities, the largest in the case of N-(2-aminoethyl)-3-(trimethoxysilyl) propylamine. Water thermoporosimetry was found to be the most sensitive method, allowing to quantify these differences.

Measurements of temperature-programmed desorption and adsorption of n-hexane and n-heptane under quasi-equilibrium conditions (QE-TPDA) were performed for several zeolites in TPD apparatus equipped with a TCD detector. One-step adsorption profiles for zeolites X and Y and two-step adsorption profiles for beta, L, 5A and ZSM-5 were observed. Approximate adsorption isobars calculated from the QE-TPDA profiles did not depend on the heating/cooling rate, proving equilibrium control of the adsorption degree. Values of the adsorption enthalpy and entropy, computed by fitting the Langmuir or dual site Langmuir model functions to the temperature derivatives of the experimental adsorption isotherms, were in agreement with the literature data. New method for determination of the initial (zero coverage) adsorption heat by fitting the linearized Henry function to the transformed high temperature experimental data was proposed. Values of the initial adsorption heat were close to those obtained using the inverse gas chromatography infinite dilution method.

Thermodesorption of n-hexane and n-nonane from the acidic and non-acidic zeolites ZSM-5 and Y was studied by means of the thermogravimetric temperature programmed equilibrated desorption (TPED) and quasi-equilibrated temperature programmed desorption and adsorption (QE-TPDA). Micropore volumes determined from the adsorption capacity of n-hexane were close to those determined by N2 adsorption. Content and strength of acid sites in the acidic zeolites estimated by fitting the Arrhenius equation to the high temperature parts of QE-TPDA profiles of n-hexane attributed to its cracking were in agreement with their acidity characteristics obtained by IR spectroscopy of chemisorbed pyridine. The mesopore volume was determined from the QE-TPDA profiles of n-nonane. Coking observed only for QE-TPDA of n-nonane on H-USY zeolite resulted in blocking the micropores without affecting the mesopores.

Measurements of temperature programmed desorption and adsorption of n -nonane in quasi-equilibrated conditions using TPD apparatus equipped with a TCD detector were performed for some microporous (zeolites HZSM-5 and HY) and mesoporous materials (MCM-41 and SBA-15). Complex adsorption/desorption profiles with high temperature desorption peaks related to adsorption in the micropores and low temperature peaks attributed to capillary condensation in the mesopores were observed. Diameters of the mesopores calculated from the thermodesorption data (basing on the Kelvin equation for capillary condensation and the Henry function for the adsorbed film thickness) are in agreement with those determined from N 2 adsorption isotherms. Values of the adsorption heat of n -nonane were determined by fitting the Henry function to the high temperature range of the integrated thermodesorption profiles.

Temperature programmed desorption and adsorption (TPDA) studied under quasi-equilibrium conditions using typical flow TPD setup equipped with a chromatographic TCD detector has been found a good method of obtaining the equilibrium data characterizing adsorption of n -hexane on high silica HZSM-5 and HY zeolites. The equilibrium control of sorption has been confirmed by linearity of the isosters constructed from the TPDA profiles. For HZSM-5 it was corroborated by very good agreement obtained in fitting the experimental data with the model based on the dual site Langmuir (DSL) adsorption function. The values of the adsorption enthalpy and entropy, either determined from the adsorption isosters or as the fitted model parameters, were close to the literature data. Increase of the isosteric adsorption heat of hexane with coverage was observed for both zeolites (72–90 kJ mol −1 for HZSM-5 and 46–61 kJ mol −1 for HY).

Gravimetric measurements of thermodesorption of n-hexane and n-heptane were performed under quasi-equilibrium conditions. Differential thermodesorption profiles for ZSM-5 and ZSM-11 showed two peaks, but for Y zeolites, only one thermodesorption peak was observed. A model function, derived from the Langmiur adsorption model, was fitted to the experimental data, and the model parameters (the adsorption entropy and enthalpy) were estimated. The two-step desorption profiles observed for ZSM-5 and ZSM-11 were attributed to the commensurate freezing effect, i.e. a transition in the adsorbed phase resulting in ordering of the adsorbed molecules in the zeolite channels. The results observed for ZSM-11 indicate that the zigzag channels typical for ZSM-5 micropore system are not necessary for this transition to occur.

Are there any chances to increase oxygenates yield in partial oxidation of methane (MPO) to economically efficient level? The effect of various homogenous promoters of MPO was studied in terms of their role in the MPO mechanism on vanadia silica supported catalyst. Accordingly they were classified into three groups: equilibrium shifting (H2O), reducing (H2) and intermediate supplying (MeOH, EtOH, CH2Cl2). The most profound promoting effect was exhibited by H2, which decreased MPO temperature by 50–520 °C, at which unpromoted MPO gave no products. Among organic promoters the most efficient with respect to the added amount appeared ethylene, which enhanced both formaldehyde yield and methane conversion and also methanol. In the presence of these promoters the achieved HCHO yield was comparable to the highest values reported in the literature (1200 g HCHO per kg catalyst per h). The contribution of organic additives to the formaldehyde yield was experimentally excluded.

Porous N-doped carbon materials of various morphologies are prepared via chemical vapor deposition (CVD) at 700 °C using acetonitrile as carbon and nitrogen source and MgAl, MgCoAl, CoAl layered double hydroxides (LDHs) as template and catalyst precursors. The physicochemical properties of the carbon materials are characterized by powder X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, thermogravimetric analysis, elemental analysis, nitrogen sorption and n -nonane thermodesorption, whereas their electrochemical performance is evaluated in 6 M KOH by means of cyclic voltammetry, galvanostatic charging/discharging and electrochemical impedance spectroscopy. The choice of LDHs strongly affects the grain morphology and micropore/mesopore contribution in the synthesized carbon materials, which determines their capacitive performance. The application of Co-free LDHs leads to the carbon material consisting of irregular aggregates of plate-like particles highly doped with nitrogen (9.7 wt%) and having high specific surface area (863 m 2 g −1 ) and high capacitance (130 F g −1 ). On the other hand, the use of Co-containing LDHs results in the carbon materials predominantly made of carbon nanotubes (grown on metallic Co nanoparticles) less doped with nitrogen (2.4–3.1 wt%) and having lower specific surface area (193–225 m 2 g −1 ) and lower capacitance (15–30 F g −1 ).

Thermoporosimetry, based on DSC measurements of melting point depression of water, n-hexane and n-heptane confined in mesopores has been used for determination of the pore size distribution, average pore diameter and pore volume of series of SBA-15 mesoporous silicas. Porosity of these materials was additionally characterized by low-temperature nitrogen adsorption and quasi-equilibrated thermodesorption of n-nonane. In general, the pore sizes and pore volumes determined using water and alkanes TMP reveal the same tendency as those calculated with other methods, although the absolute values show some differences. In particular, pore diameters found from water and n-hexane TPM experiments are in most cases smaller in comparison with the results obtained from other methods. On the other hand, in the case of solids with largest pores, the pore diameters found on the basis of n-heptane TPM are significantly overestimated. The values of the pore volume corresponding to the integral intensity of the TPM PSD peaks are smaller than those calculated with other methods. The possible reasons for the observed deviations are discussed. For the first time important differences in the behavior of n-hexane and n-heptane in TPM experiments are reported and attributed to different packing of C6 and C7 alkane molecules in the solidified state due the alternations in the properties of odd and even numbered hydrocarbon chains.

MCM-56 is a unique zeolite with MWW topology consisting of 2.5 nm thick mono-layers. It is formed as an intermediate converting into the 3D MWW zeolite, MCM-49. It is attractive for catalysis with well documented high activity for hydrocarbon conversions but as a transient product MCM-56 presents novel challenges with regard to synthesis and activation. This work describes application of IR spectroscopy to monitor MCM-56 formation by investigating solid products obtained at different times during hydrothermal synthesis with hexamethyleneimine as template. We identified a unique double band in the range 500–600 cm −1 , which can be assigned to skeletal vibrations of D6R units, that appears upon formation of MWW framework and can be used for quantitative determination of its content in a sample. The integrated intensity correlates well with XRD crystallinity, micropore volume and Bronsted acid sites concentration. FTIR approach allows facile and fast measurement and therefore may complement and possibly supplant XRD and porosity for reliable quality control in the course of MCM-56 crystallization, e.g. for the purpose of rapid termination of the synthesis at ‘the optimal time’.

Different functions of the carbonaceous deposits have been recognised in ethylene hydrogenation ( 150 ° C °C) over the model cobalt foil catalyst: retarding, blocking and activating. The carbonaceous deposits were investigated by TPO, TPR and SEM methods. Their quantitative results were related to the number of metallic active centres measured also by TPO and TPR. It has been shown that retarding the reaction rate by the hydrocarbon deposit takes place below 300 °C; blocking the catalyst by the dehydrogenated deposit occurs between 300 and 400 °C; restoring the catalyst activity above 400 °C. The renewed activity was explained by the diffusion of cobalt atoms to a deposit surface.