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The separation of layered MFI into unilamellar nanosheets in solution confirms the general validity of soft-chemical exfoliation for zeolites and allows top-down production of films with potential applications in separation and catalysis.

Furfural is a renewable lignocellulose-derived platform molecule, which can be transformed into biofuels and value-added chemicals (e.g., furfuryl alcohol and 2-methylfuran over metal-supported catalysts). Despite a number of approaches proposed for designing hydrogenation catalysts, highly selective furfural hydrogenation towards furfuryl alcohol (FA) or 2-methylfuran (2-MF) is still challenging. Here, we report on selective transformation of furfural either to FA or 2-MF achieved over zeolite BEA-supported Rh catalysts by optimizing Si/Al ratio and charge-balancing cations of the support. Among studied H- and Na-exchanged aluminosilicate BEA zeolite supports (Si/Al = 12.5; 25; 68; 150), Rh@Na-BEA catalysts lacking Bronsted and strong Lewis acidity showed enhanced selectivity towards FA (75 – 94% depending on the Si/Al ratio) at 74 – 84% conversion of furfural. In turn, selective formation of 2-MF (98% selectivity at 87% conversion) was observed over Al-rich Rh@H-BEA catalyst (Si/Al=12.5) with the highest concentration of Bronsted acid sites. Weaker adsorption of FA on Na- vs. H-form of Rh@BEA-12.5 catalyst was verified by FTIR spectroscopy and is assumed a key factor governing selective hydrogenation of furfural to FA over Rh@Na-BEA catalysts.

Nanoporous crystalline aluminosilicates, zeolites, are synthesised by solvothermal method producing three-dimensional (3D) crystals. An alternative, more controllable approach of zeolite synthesis - ADOR – can be used for preparation of isoreticular zeolites with tuneable porosity. Zeolites porosity allows their wide use as isomerisation catalysts due to their shape selectivity effects. Selective isomerisation of m-xylene towards p-xylene is an industrially important reaction due to a high demand for the latter as a substrate for terephthalic acid production. In this work, we investigated the influence of pore size (shape selectivity effect) on the isomerization of m-xylene using a system of isoreticular Al-containing zeolites. These materials, prepared by ADOR approach (UTL, IPC-7, IPC-2, IPC-6, and IPC-4) had different layers connectivity, and therefore various channel systems. We tracked the influence of the pore systems of ADOR zeolites (8- up to 14-ring channels) on the catalytic performance in gas-phase m-xylene isomerisation. We investigated the crystallinity and interlayer distances, phase purity, textural properties of prepared materials, their crystals morphology, and aluminium content. M-xylene isomerisation was carried out in a fixed-bed reactor at 350 °C. ADOR catalysts were compared with standard ZSM-5 zeolite. We show the dependence of zeolite porosity on the performance in isomerisation of m- to p-xylene. Smaller pore zeolites: IPC-4 (8- and 10-ring channels) and IPC-6 (8-, 10- and 12-ring channels) exhibited the lowest conversions, while the highest conversion and p-xylene yields were observed for IPC-2 (10- and 12-ring channels). Presence of extra-large, 14-ring channels (IPC-7 and UTL) resulted in the drop of selectivity due to the xylene disproportionation.

Titanosilicate zeolites are a prominent class of catalysts applied in various oxidation reactions, including epoxidation of alkenes. Numerous studies have been performed to understand the influence of Ti sites structure (‘open’ vs. ‘closed’) and their distribution between internal and external surface of zeolite on the catalyst performance, although the effect of Ti location in micropores of different sizes remained unrevealed. Here, we report the application of ADOR synthesis strategy for the preparation of model ‘isoreticular’ titanosilicate zeolites with the same topology but continuously tunable porosity for addressing the influence of micropore confinement on the activity and selectivity of the catalysts in alkene epoxidation reaction. A set of ‘isoreticular’ Ti-IPC-n (n = 2, 4, 6, 7) zeolites were synthesized by post-synthesis of Ti-substituted UTL germanosilicate. Structural, textural and acidic properties of the prepared catalysts were characterized by XRD, nitrogen physisorption, FTIR spectroscopy of adsorbed d3-acetonitrile, while their activity and selectivity were compared in the epoxidation of 1-hexene and cyclohexene as model linear and cyclic alkenes with hydrogen peroxide as oxidant. The obtained results confirmed the successful preparation of Ti-substituted IPC-n zeolites with similar total concentration of Ti sites (0.15–0.17 mmol/g). For both 1-hexene and cyclohexene epoxidation, the specific activity of a Ti active center (TOF) gradually decreased with the micropore size in a sequence Ti-UTL (TOF1-hexene = 126 h−1; TOFcyclohexene = 227 h−1) > Ti-IPC-7 (124; 143) > Ti-IPC-2 (124; 130) > Ti-IPC-6 (90; 67) > Ti-IPC-4 (64; 37). In line with reducing diffusion limitations of substrates and products, the site time yield of both targeted epoxides increases with increasing the size of the pores in ‘isoreticular’ zeolites reaching the maximal value for Ti-UTL (586 and 491 h−1 for 1,2-epoxyhexane and cyclohexeneoxide, respectively).

2D-to-3D transformation of layered zeolite precursors (e.g., MCM-22P, IPC-1P, pre-FER) into three-dimensional frameworks in combination with metal encapsulation has been recently shown as efficient synthetic strategy to stabilize metal clusters in a zeolite matrix. Even though, tailoring the number of acid sites in a zeolite support and its effect on the properties of thus prepared metal@zeolite materials (e.g., metal dispersion and catalytic activity) remained unrevealed. Herein, we report on the synthesis of Pd@MCM-22 catalysts via modified 2D-to-3D transformation method, which allows to achieve close to nominal loading of noble metal (e.g., 0.1, 0.3, 0.8 wt.%) by time-separation of swelling of MCM-22P layered zeolite precursor and subsequent incorporation with metal. In turn, alternating Si/Al ratio of MCM-22P (e.g., Si/Al = 15, 20, 30) enabled the preparation of Pd@MCM-22 catalysts with variable concentration of acid sites (0.28 – 0.55 mmol/g), while not affecting the Pd dispersion. Decrease in Pd dispersion with increasing metal loading was accompanied with declining catalytic activity in a model reaction of selective hydrogenation of nitro-group in 3-nitrotoluene: 0.1 wt. % Pd (dispersion = 52.6%, reaction rate = 21.2 mol·g-1Pd·h-1) > 0.3 wt. % Pd (9.6 mol·g-1Pd·h-1) > 0.8 wt. % Pd (23.2%, 3.7 mol·g-1Pd·h-1). The results of this study reveal that the reported synthesis strategy can be successfully used to confine small metal nanoparticles in a zeolite matrix while tuning its acidic characteristics for designing bifunctional metal-acidic catalysts.

Hydrogenation of nitroarenes is a catalytic reaction of high interest owing to the importance of the resulting aromatic amines in the chemical industry. Up to date, various metal@zeolite catalysts have been reported for this transformation. Herein, Pd@Beta and Pd@MWW catalysts were synthesized by ion exchange with Pd(NH3)4(NO3)2 and characterized by XRD, nitrogen sorption, ICP-OES, electron microscopy and FTIR(CO). Structural and textural analysis proved no significant changes of the zeolites after the Pd precursor was introduced. STEM images proved the uniform distribution of metal species in zeolite crystals. Average size of Pd NPs is 2.6 nm and 1.7 nm for Beta and MWW zeolites, respectively. The resulting Pd@Beta catalyst exhibited higher catalytic activity compared to Pd@MWW in the hydrogenation of nitroarenes. The electronic/steric effects of substrates and products were also investigated for both catalysts. Nitroarenes with electron-donating groups exhibit higher initial reaction rates than nitroarenes containing electron-withdrawing groups. The nitroarenes bearing functionalized groups in the ortho-position are harder to hydrogenate than corresponding meta- and para- isomers because of the steric hindrance effect.

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.

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.

The zeolite activity in processes driven by Bronsted acid sites is determined by the distribution of the protons in the zeolite and strength of their interaction with the framework. This study aims to assess how much the transformation from three-dimensional (3D) bulk zeolite to its corresponding two-dimensional (2D) layered form changes the proton distribution and strength of the proton-framework interaction and thus how much it affects the zeolite Bronsted acid strength. Zeolites with three distinct topologies, MWW, PCR, and MFI, which form also layered analogues with considerably different thickness and silanol density were considered. To probe the Bronsted acidity of both 3D and 2D forms, an array of typical acidity descriptors (i.e., O-H stretching frequency, shift of O-H frequencies upon adsorption of CO probe molecule, C-O stretching frequencies and adsorption enthalpies of the CO adsorption complex) have been evaluated, employing both dispersion-corrected density functional theory and Fourier-transform infrared spectroscopy. Using these descriptors, the Bronsted acidity of 2D form is, on average, the same or just slightly lower than that of the 3D form. Transformation to layered form does affect the proton distribution and values of acidity descriptors for individual T sites, however, if all T sites are considered, the aggregate effect is almost negligible. Hence, these results suggest that a larger effect of the 3D -> 2D transformation can be expected for frameworks with fewer distinct T sites.

Zeolites with encapsulated metal nanoparticles (NPs) attract much attention due to the catalytic activity, stability and shape-selective properties of such materials in heterogeneous catalysis. One of the methods for introduction of metal NPs into the zeolite system is based on use of two dimensional (2D) layered precursors that are loaded with Pt source and consecutively transformed to three dimensional (3D) zeolites. This method can be combined with recently developed approach for zeolite synthesis; the ADOR (Assembly, Disassembly, Organization, and Reassembly) approach that is based on the 3D-2D-3D transformation of zeolites. Here, we report a synthesis of two ADOR zeolites: IPC-2 (OKO topology) and IPC-4 (PCR topology) functionalized with Pt NPs, Pt@IPC-2 and Pt@IPC-4, respectively. Pt@IPC-2 was prepared by intercalation of platinum(0)-2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetra siloxane into IPC-1P layered precursor and subsequent calcination. Pt@IPC-4 zeolite was prepared by the swelling of IPC-1P with the mixture of surfactant and Pt source. Final materials were investigated by XRD, nitrogen sorption, ICP-OES, and electron microscopy (SEM and STEM). Structural and textural analysis confirmed the successful syntheses of two ADOR zeolites. The size and distribution of Pt NPs were investigated by STEM. The platinum content was 0.34 wt% and 0.32 wt% and the average size of Pt NPs of 0.98 nm and 0.96 nm for Pt@IPC-2 and Pt@IPC-4, respectively. Pt@IPC-2 exhibited a broader range of Pt sizes due to larger pores.

Acid site strength in MWW and MFI zeolites was investigated by isotopic exchange reaction between deuterated hydroxyl groups of zeolites and ethane molecules. The course of the reaction was monitored by FT-IR spectroscopy through time changes of integral intensities of the Si(OD)Al Bronsted acid sites represented by absorption bands at 2644, 2655, and 2657 cm−1 for MFI, MWW and MCM-36 zeolite, respectively. The rate of the reaction was described by pseudo first order kinetics and acid site strength was compared using rate constants characteristic of individual zeolites at constant temperature. The exchange reaction is significantly faster over MFI zeolite compared with MWW zeolites, suggesting a higher acid strength of Bronsted sites in MFI zeolite than in MWW. In our previous study (Arean et al. Phys. Chem. Chem. Phys. 16 (2014) 10,129), we found notable discrepancy in the relation between OH group frequency shift induced by adsorption of weak base molecules like CO and N2 and the change of adsorption enthalpy of these probe molecules for MWW zeolites, which calls into question the use of frequency shifts as a measure of acidity. Our reported results based on isotopic exchange reaction rate measurement correlate with the change of the probe molecules adsorption enthalpy involved in hydrogen bonding. Therefore, we believe that enthalpy change or H/D exchange activity measurement is more reliable method for assessment of acid strength than O H frequency shift probed by a weak base adsorbed at a low temperature.

Zeolites doped with metal nanoparticles have shown the outstanding activity in many processes involving heterogeneous catalysis. The size of metal nanoparticles plays a decisive role in the performance of zeolite catalysts. However, the precise control of the size of nanoparticles is still limited. Herein, we present the synthesis of Pt-MWW zeolites with controllable nanoparticle size using a series of surfactants with different alkyl chain lengths for swelling of layered MCM-22 P. The interlayer distances of swollen materials increases with the length of the surfactant from 1.06 nm (C12OH) to 2.89 nm (C18OH). During swelling, the Pt nanoparticles were intercalated to the interlayer space of MCM-22 P. Further calcination resulted in Pt-MWW materials showing similar morphologies, textural properties and Pt content despite the differences in the initial interlayer distances. The factor that differentiated the synthesized materials was the average diameter of metal nanoparticles. As a result, the average size of Pt nanoparticles increased from 0.85 nm (MCM-22-C12OH-Pt) to 2.04 nm (MCM-22-C18OH-Pt) which is related to the length of the hydrocarbon chain of the surfactant used for the swelling process.

Since the discovery of synthetic zeolites in the early 1950 s, a significant progress has been made in the area of zeolite science. Zeolites have found widespread applications in industrial processes because of their unique porous structures and properties. In the last decades, a number of new zeolites were discovered - some of them with interesting structural features for further research. This review discusses recent advances in the synthesis, characterization, and catalytic applications of well-known 10-ring zeolites: MEL, MFI, MWW, EUO, *MRE, MTT, STF, TON and novel TUN, IMF, -SVR, MVY, JRY, JST and SFG which are among the most crystallographically complex zeolites known to date. Strategies to tailor the properties of zeolites by post-synthesis techniques to enhance the catalyst effectiveness are described and the relation among the structures, activities and selectivities is discussed.

New zeolitic frameworks can be prepared through the Assembly-Disassembly-Organisation-Reassembly (ADOR) process by exploiting the lability of Ge-O bonds in germanosilicate zeolites to control their hydrolysis. In the disassembly step, two key factors are water and germanium content, but their exact roles remain unknown. Nevertheless, we combined experimental water-vapor adsorption with first principles simulations to identify the mechanism of germanosilicate zeolite disassembly. The results showed that water vapor adsorption on UTL germanosilicate proceeds in reversible (at low partial pressures) and irreversible (at higher partial pressures) modes. Based on our ab initio molecular dynamics simulations, we related these two modes to weak physisorption at low water loading and to reactive transformations at high water loading, via collective mechanisms requiring high local water concentrations. This bimodal behavior also depends on the germanium content as high Ge-content further decreases UTL hydrolytic stability by opening up yet another low-energy disassembly pathway at high water loading. Overall, we discovered, verified and explained the mechanisms of UTL disassembly and its factors. These findings will likely be generalized to other ADORable germanosilicate zeolites and help to find the optimal protocol for the synthesis of new zeolites.

SSZ-70 is one of several layered forms of zeolite MMW obtained by direct synthesis with consecutive layers shifted by approximately ±1/3 of a unit cell in the horizontal direction (⟨110⟩), according to the recent structure solution report. Zeolite MWW is a valuable industrial alkylation catalyst and SSZ-70 itself was called by the inventors 'a successful catalytic material'. SSZ-70 shows characteristic powder X-ray diffraction pattern (XRD), containing a unique broad band with a roughly triangular shape and maximum at 8.5–9.0° 2θ (Cu Kα radiation), which can be used to distinguish SSZ-70 from the other MWW materials with different layer arrangements. This work concerns post-synthesis treatments of SSZ-70 to investigate its ability to produce more expanded structures by silylation, swelling and pillaring. Both boron- and aluminum-containing SSZ-70 were investigated. They showed the ability for interlayer expansion by swelling with cationic surfactants and were pillared with silica to produce micro/mesoporous hybrids with increased BET area. Not too surprisingly, the original unique layer stacking of SSZ-70 seems to have become more random and not distinguishable from the swollen forms of the other swellable MWW materials MCM-22 P and the monolayer MCM-56. Calcined SSZ-70 zeolites showed an unusual peak, assigned to (002) reflection, with d-spacing shorter than c-unit cell of the 3D MWW framework, which suggests collapse with formation of the so-called sub-zeolite form. Silylation resulted in different outcomes for B and Al SSZ-70 samples. The former produced interlayer expanded (IEZ) forms of B-SSZ-70 but did not show significant increase in pore volume and BET surface area. Silylation of Al-SSZ-70 did not yield the stabilized (IEZ) form but had a positive effect as it prevented the collapse to sub-zeolite upon calcination. Catalytic testing was carried out for the Al-containing SSZ-70 obtained by direct synthesis and for B-SSZ-70 activated by Al insertion. The former showed much higher concentration of Bronsted acid sites and 5 times faster conversion in a model alkylation reaction between benzyl alcohol and mesitylene. Pillared Al-SSZ-70 showed highest activity despite lower Al concentration due to silica pillars. Both silylation and pillaring had a positive effect on the activity in alkylation reaction with bulky molecules.

A Hoveyda-type catalyst decorated with two quaternary ammonium tags was synthesized and noncovalently grafted on SiO2, SBA-15, and on carboxyl graphene. A comparative study showed that the efficiency of the dual-anchored heterogeneous catalysts was highly dependent on the properties of the supporting material with graphene outperforming silicate supports. The graphene-immobilized complex exhibited excellent efficiency reflected in turnover numbers obtained in ring-closing metathesis and in self-metathesis of 1-decene. Importantly, the solid-supported catalyst assured increased recyclability with no ruthenium leaching as confirmed by inductively coupled plasma mass spectrometry.

Cardanol (a mixture of phenols with C 15 aliphatic unsaturated chain in meta position, manufactured from cashew nut shell liquids) is an abundant and till now practically waste natural material. An important way leading to its utilization as a renewable source of valuable phenolic compounds is represented by olefin metathesis. Quaternary ammonium tagged Ru complex of Hoveyda-Grubbs type immobilized on SBA-15 mesoporous molecular sieve by non-covalent interactions was proved as a very efficient catalyst for cardanol metathesis under mild conditions (35 °C, toluene, 0.1 mol% of catalyst). The catalyst was used also in cross-metathesis of cardanol with alkenes (1-hexene, 1-heptene, 3-hexene, 4-octene) and unsaturated esters (methyl acrylate, 1,4-diacetoxybutene-2) under high yields of cross-metathesis products. The catalysts exhibited low leaching (from 0.2 ppm to 2.9 ppm Ru in products) and can be used in a continuous flow reactor (cumulative TON = 2500).

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.

MWW-type zeolites with different textural properties, namely, MCM-22, MCM-36, MCM-56, and MCM-49, were synthesized and tested in the selective preparation of campholenic aldehyde by isomerization of α-pinene oxide. Commercial zeolites USY, Beta, and ZSM-5 were compared. The physico-chemical properties of the studied zeolites were correlated with their catalytic performance in the isomerization of α-pinene oxide carried out either in toluene as a solvent at 70 °C or in N,N-dimethylacetamide at 140 °C. α-Pinene oxide isomerizes easily in the presence of acids and therefore, high conversions were achieved over commercial as well as synthesized MWW catalysts. Higher selectivities to campholenic aldehyde were achieved over MWW catalysts in basic N,N-dimethylacetamide while non-basic toluene enhanced the formation of the desired aldehyde over all the commercial zeolites. The highest selectivity to the desired aldehyde was achieved over MCM-22 in the reaction performed in N,N-dimethylacetamide at 140 °C, being 83% at total conversion of α-pinene oxide. This is the best result achieved rivaling homogenous acids (ZnBr2) and metal–organic frameworks.

Magnesium oxide has been introduced into zeolites MCM-22, MCM-36, IPC-3, IPC-3PI and ITQ-2 synthesized from 2D layered precursors MCM-22P and ICP-3P. Prepared materials were tested as carbon dioxide adsorbents in the temperature range from 0 °C to 60 °C. For parent zeolites, the IPC-3 has shown at 1 kPa the adsorption capacity (5.1 cm 3 /g STP), which was nearly two times higher than that of MCM-22 (2.7 cm 3 /g STP). Adsorption capacity of zeolites in the low pressure region markedly increased due to incorporation of magnesium oxide. The amount adsorbed on MgO-IPC-3 and MgO-MCM-22 at 1 kPa was enhanced to 11.4 and 13.7 cm 3 /g STP. Isosteric adsorption heats giving information on the energetics of CO 2 adsorption were calculated.

Molybdenum and tungsten oxides were supported on silica, MCM-22, MCM-41 and SBA-15. XRD and N2 adsorption–desorption revealed that architecture and textural character of supports were preserved. The catalysts were investigated in transformation of 2-pentene at different reaction temperatures. MoO3/MCM-22 exhibited highest conversions with isomerization and cracking as major reactions. MoO2(acac)2, MoO3 and WO3 supported on MCM-41 and SBA-15 showed metathesis reaction of 2-C5= producing propylene, C4= and C6+=as major products. Catalysts based on MCM-41 exhibited higher activity and stability than SBA-15. Addition of ethylene to 2-C5= increased selectivity to propylene due to metathesis of ethylene with 2-pentene.

Homopolymerizations of 2,5-diethynylthiophene into conjugated microporous polymers by (i) chain-growth polymerization and (ii) polycyclotrimerization are described. Both methods provide nearly quantitative yields of thiophene-rich (7.6 mmol thiophene rings/g) networks with specific surface area up to 839 m2/g. The thiophene units enhance the affinity of the networks to CO2 and red-shift the UV/vis and fluorescence absorption and emission bands of the networks, respectively.

The cracking behaviour of three medium-pore zeolites -SVR, ITH, and MFI, with varying Si/Al molar ratio, was evaluated using an equilibrium FCC catalyst (E-Cat) and a hydrotreated vacuum gasoil (VGO) in a microactivity test unit (MAT). The increase in the yield of light olefins (21–29 wt% over E-Cat/additive vs. 16 wt% over E-Cat) was accompanied by a drop in the yield of gasoline (26–39 wt% over E-Cat/additive vs. 43 wt% over E-Cat) due to the cracking of reactive species in gasoline fraction (mainly olefins and isoparaffins). With increasing Si/Al ratio in zeolites MFI-280 and –SVR-120, propylene yield passed through maxima reaching 13.5 wt% and 12.8 wt%, respectively, compared with 7.0 wt% over E-Cat. Maximum propylene yield occurred partially due to gasoline over-cracking to light olefins (inverse relation with Si/Al ratio). The effect of MFI crystal size showed that large size crystals enhanced the yield of light olefins as compared to small size crystals due to secondary cracking of gasoline molecules. Results of kinetic study based on 4-lump model showed proportional relation between MFI Si/Al ratio and activation energy for the conversion of gasoline to gases. Activation energy increased from 14.2 kcal/mol to 16.3 kcal/mol as Si/Al ratio increased from 30 to 2000.

Ethyltoluenes (ET) synthesis via different alkylation routes; toluene with ethanol and ethylbenzene (EB) with methanol, was investigated over zeolites with three-dimensional (3D) pore system i.e. SSZ-33, TNU-9, ZSM-5, IM-5, and one-dimensional zeolite MOR in a fluidized-bed reactor in the temperature range 250–350 °C for reaction times of 5–20 s. Alkylation of toluene with ethanol provided higher yields and selectivities to ethyltoluenes over all zeolites. The maximum ET yield achieved for toluene ethylation was 13.7 wt.% using IM-5 and ZSM-5 whereas 12.5 wt.% was obtained in EB methylation over SSZ-33. SSZ-33 provided the highest ET-selectivity of ∼50% due to the combine effect of its 3D topology and 12-ring channels. In contrast to ET selectivity, p-ethyltoluene selectivity was almost the same, ∼26%, irrespective of the zeolite topology. Kinetic studies of toluene ethylation over the zeolites were conducted using power law coupled with time-on-stream deactivation model. A satisfactory correlation between experimental data and the model result was achieved. The activation energy of the various zeolites used for the alkylation of toluene to ET decreased in the order: IM-5 (58.2 kJ/mol) > SSZ-33 (39.7 kJ/mol) > TNU-9 (27.3 kJ/mol) > MOR (20.2 kJ/mol) > ZSM-5 (17.0 kJ/mol) which was explained by different acid strength and nature of the zeolites.

Zeolites loaded with metal nanoparticles (NPs) stand out for their distinct activity and selectivity as heterogeneous catalysts. However, the poor stability of metal species limits their applications. Herein, we report a novel synthetic strategy for stabilizing metal nanoparticles inside the MFI zeolite. For the first time, alkoxysilane functional imidazolium-type ionic liquids (ImILs) were used as assistant agents to protect metal precursors (Pt and Pd) against precipitation during the hydrothermal synthesis of the MFI zeolite. The positively charged imidazolium groups in ImILs interact with the negatively charged metal precursors (PtCl42−, PdCl42− etc.), while the alkoxysilane groups participate in zeolite crystallization. Scanning transmission electron microscopy images indicate that most of the Pt and Pd nanoparticles (average diameters of approximately 1.0 nm and 1.7 nm, respectively) are confined in channels or intersections of the MFI zeolite. The shape-selectivity effect on nitroarene hydrogenation over Pt@MFI_ImILs confirmed the successful encapsulation of metal NPs into the MFI matrix. The conversion of the small molecule 4-nitrotoluene is >99%, whereas the bulky 1,3-dimethyl-5-nitrobenzene shows 5.8% conversion. Simultaneously, the Pd@MFI_ImILs catalyst affords a higher reaction rate (25 mmol/s/gMe) than the impregnated Pd@MFI_Imp catalyst (9 mmol/s/gMe) in propene hydrogenation, which is ascribed to the uniform distribution of Pd nanoparticles. The ImIL-assisted synthesis strategy can be therefore successfully used to confine small metal nanoparticles in the MFI zeolite while maintaining its high catalytic activity and shape-selectivity.

Symmetric ethers can be synthesized through the acid-catalyzed self-etherification of biomass-derived alcohols. However, synthesis of asymmetric ethers via catalytic cross-etherification of alcohols is limited by poor selectivity. Herein, we developed an efficient zeolite-catalyzed one-step synthesis of valuable asymmetric cyclopentyl methyl ether (CPME) using gas-phase reaction of bio-based cyclopentanol and methanol. Among different medium- (FER, MCM-22, ZSM-5) and large-pore (BEA, MOR, USY) aluminosilicate zeolites, commercial ZSM-5 catalysts with 2D system of intersecting channels are markedly more selective to CPME. The targeted CPME was produced with a selectivity of 83 % and a yield higher than 80 % over the ZSM-5 catalysts with Si/Al ratios ranging from 15 to 40. Decrease in Si/Al ratio in ZSM-5 enhanced the conversion value, while not affecting the selectivity. FTIR study of the step-by-step adsorption of both reactants in ZSM-5 evidenced the Rideal-Eley mechanism with cyclopentanol adsorbed on acid sites. Therefore, heterogeneously catalyzed gas-phase cross-etherification of renewable cyclopentanol and methanol is a promising process for large-scale applications thanks to its mild operating conditions, high yields and selectivity when using commercial ZSM-5 zeolites as catalysts.

Catalytic cracking of vacuum gas oil (VGO) was carried out in a microactivity test (MAT) unit. Commercial FCC USY catalyst (E-Cat) is used and modified by various zeolites with different pore structures, namely SSZ-74, SSZ-33, MCM-22, MCM-36, ZSM-5, TNU-9, IM-5, and ferrierite to enhance propylene yield. Adding zeolite additives to E-Cat increased catalyst activity. The highest propylene yield of ∼11 wt.% was achieved over ferrierite and MCM-36 compared with 7 wt.% over E-Cat. An increase in light olefins yield over all additives was associated with a decrease in gasoline yield due to the cracking of gasoline-range reactive species (mainly olefins and iso-paraffins). Zeolite SSZ-74 showed a good enhancement in light olefins yield up to 21.3 wt.% compared with 16.1 wt.% over E-Cat. It is found that additives with lower ability to carry bimolecular reactions are more selective to light olefins. Gasoline quality was improved as the octane number increased over E-Cat with all additives except MCM-36.

Three-dimensional 10-ring zeolites TUN, IMF, –SVR, MFI and MEL were investigated as for their acid properties, adsorption of 2,2-dimethylbutane and in toluene disproportionation and its alkylation with isopropyl alcohol. The results were compared against zeolite *SFV, the structure of which consists mainly of MEL zeolite with some additional 12-ring channel system. With exception of –SVR synthesized with high Si/Al ratio, all other zeolites provided Si/Al ratios in a narrow region. Novel zeolites TUN, IMF, and –SVR exhibited higher conversions than MFI and MEL in toluene alkylation. TUN and IMF were substantially more active in toluene disproportionation indicating less diffusion restrictions of channel structure on the disproportionation reaction. *SFV showed a similar catalytic behavior to MEL with much lower selectivity to p-xylene and p-cymene. This could indicate that both toluene disproportionation and alkylation proceed in reaction space of *SFV being similar to those of MFI and MEL. *SFV and TUN exhibited much faster adsorption of 2,2-dimethylbutane than MFI, MEL, IMF, and –SVR. It was concluded that the presence of some larger transport pores in *SFV than in other zeolites is responsible for fast adsorption of 2,2-dimethylbutane and transport of products resulting in a low selectivity to p-xylene and p-cymene.

TS-1-based catalysts with different textural features, namely layered TS-1, pillared TS-1, and Ti-pillared TS-1 as well as mesoporous TS-1, were investigated in the liquid-phase epoxidation of methyl oleate as a model compound for plant oil-derived substrates with hydrogen peroxide at 50 °C. While over the TS-1-based catalysts, except Ti-pillared TS-1, an epoxide selectivity of up to 93% is achieved, layered and pillared TS-1 are the most active (the amounts of methyl oleate converted after 5 h per number of Ti-sites are 4.64 mol mol−1 and 4.68 mol mol−1) with an efficiency for H2O2 conversion to the epoxide of 27%. Mesoporous TS-1 and conventional microporous TS-1 exhibit a similar activity (3.64 mol mol−1vs. 3.37 mol mol−1), whereas the mesoporous catalyst most efficiently utilizes H2O2 (39% efficiency). The lowest catalytic activity (0.82 mol mol−1), epoxide selectivity as well as H2O2 efficiency are observed over Ti-MCM-36, possessing mainly octahedrally coordinated Ti-sites. The results demonstrate the importance of accessibility of Ti-sites at external crystal surfaces within layered and pillared TS-1, significantly increasing the epoxidation activity with respect to the number of Ti-atoms present in the catalysts.

Metal nanoparticles (NPs) can be encapsulated into zeolites to prepare active catalysts. However, when using conventional encapsulation methods, the location of metal NPs cannot be controlled, which limits the dispersion of metal precursors. Here, we report a new strategy for the encapsulation of Pd NPs into an MWW zeolite during its 2D-to-3D transformation by introducing diethylenediamine palladium (II) acetate, Pd(en)2(ac)2, when swelling the layered zeolite precursor at room temperature. The resulting Pd@MCM-22 catalyst was investigated by X-ray diffraction, nitrogen sorption, ICP-OES, FTIR, and electron microscopy. The results showed a uniform distribution of NPs in the Pd-doped sample, which had the same nanoporous character as the ‘standard’ MWW zeolite. Moreover, the Pd@MCM-22 catalyst showed high shape selectivity and activity for the hydrogenation of 3-nitrotoluene and almost no activity for 1-nitronaphthalene. In total, 15 zeolites with different topologies have layered representatives that can be functionalized using this strategy, thereby enabling us to prepare numerous tunable microporous structures, with different zeolite-encapsulated metal NPs specifically designed for shape-selective hydrogenations.

Highly active olefin metathesis catalysts were prepared by thermal spreading MoO3 and/or MoO2(acac)2 on MWW zeolites (MCM-22, delaminated MCM-56) and on two-dimensional MFI (all in NH4 + form). The catalysts‘ activities were tested in the metathesis of neat 1-octene (as an example of a longer chain olefin) at 40 °C. Catalysts with 6 wt % or 5 wt % of Mo were used. The acidic character of the supports had an important effect on both the catalyst activity and selectivity. The catalyst activity increases in the order 6MoO3/HZSM-5(25) (Si/Al = 25) << 6MoO2(acac)2/MCM-22(70) < 6MoO3/2D-MFI(26) < 6MoO3/MCM-56(13) < 6MoO3/MCM-22(28) reflecting both the enhancing effect of the supports‘ acidity and accessibility of the catalytic species on the surface. On the other hand the supports‘ acidity decreases the selectivity to the main metathesis product C14 due to an acid-catalyzed double bond isomerization (followed by cross metathesis) and oligomerization. 6MoO3/2D-MFI(26) with a lower concentration of the acidic centres resulting in catalysts of moderate activity but with the highest selectivity.

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 (− counter anion; in contrast, PF6− counter anion underwent partial decomposition.

We report the synthesis of conjugated highly cross-linked polyacetylene-type networks with a high content of functional groups (–CH2OH, –NO2, –Ph2N, content up to 3.9 mmol/g) via a chain-growth copolymerization of either 1,4-diethynylbenzene or 4,4′-diethynylbiphenyl with functionalized mono- and diethynylbenzenes. The backbone of the networks consists of substituted polyene main chains that are cross-linked by arylene links. The optimized combinations of comonomers in the feed provide functionalized networks with a Brunauer–Emmett–Teller specific surface area up to 667 m2/g and enhanced affinity for CO2 adsorption (compared to the non-functionalized hydrocarbon networks of the same type). The dependence of the specific surface area of the networks on the size and architecture of the comonomers used for the synthesis is discussed in the paper. The reported networks can be classified into the group of conjugated microporous polymers (CMPs). Contrary to the CMPs synthesized by step-growth couplings, significantly lower average comonomer functionality in the feed (f = 1.5–2.0) is sufficient for the high specific surface area to be achieved in the reported polyacetylene-type CMPs.

Desilication conditions (concentration of NaOH, duration of the treatment) of SSZ-33 zeolite (CON topology) were investigated in respect to the textural and acidic properties of the obtained materials. As-synthesized borosilicate SSZ-33 was transformed by isomorphous substitution to Al-form. The alkaline treatment of Al-SSZ-33 zeolite resulted in the formation of mesopores and enhanced accessibility of Bronsted acid sites. The increase in the mesopore volume and also changes in the concentration of acid sites depends mainly on the concentration (pH) of the treatment. Simultaneously, the increase in the pH of the alkaline solution led to the slight increase in Bronsted acid sites and substantial decrease in the micropore volume more than 50%, in comparison with the parent material while the volume of mesopores increased significantly. All desilicated SSZ-33 zeolites are characterized by a broad mesopore-size distribution in the range of 5–20 nm with the maximum depending both on the harshness and duration of the treatment. The average size of mesopores increases with increasing pH of NaOH solution.

The unique features of the germanosilicate zeolite possessing the UTL framework topology offer various post-synthetic modifications such as ‘top-down’, ‘inverse sigma’ or solid-state transformations. The presented work describes several different synthetic routes generating the IPC-2 type zeolite (OKO topology) utilizing UTL as the parent material. In total, five approaches were investigated which exhibit this topological transformation from germanosilicate UTL to OKO type material: (1) alkoxysilylation of the layered precursor (IPC-1P) formed by hydrolysis of UTL; (2) direct conversion of UTL by treatment in 7–12 M hydrochloric acid; (3) direct transformation under mild conditions of water and ammonium nitrate solution on Al- and B-UTL; (4) repeated calcinations of boron-containing UTL; (5) using organic solutions as self-stabilization agents. Resulting materials were examined by powder XRD, nitrogen sorption, SEM and EDX. Briefly, all the materials possessed the same OKO topology but had differing BET surface areas and micropore volumes in the ranges of 201–493 m 2 /g and 0.095–0.189 cm 3 /g, respectively. The morphologies of crystals were very similar, while the size of them varied between 10 and 50 μm. The main goal of the study was to emphasize the complexity of post-synthetic UTL zeolite chemistry and the diverse range of solid-state transformations possible.

The transformation of analcime into the IMF structure during the crystallization of IMF zeolite is presented. IMF zeolite was found to show behavior similar to TUN zeolite, i.e. crystallization at the expense of an intermediate. Analcime which appeared first in the reaction mixture was further transformed into the IMF structure for aluminosilicate gels with the initial Si/Al ratio in the range of 15–20, i.e. under conditions being optimal for the synthesis of pure IMF phase and also even when seeding the final gel. The effect of synthesis conditions (Si/Al ratio, temperature, time) on the course of crystallization and properties of the high-silica IMF zeolite was investigated and compared with analcime (having the same Si/Al ratio) prepared from clear solutions not containing any organic template and using the same sources of silicon and aluminum as for the synthesis of IMF. The detailed characterization of prepared samples during crystallization is presented.

A new equation describing isotherms of C5 hydrocarbons on metal–organic framework Cu3(BTC)2 in the temperature range from 273 to 333 K was developed. The isotherms of n-pentane, isopentane and cyclopentane on Cu3(BTC)2 belonging to the Type 5 according to the IUPAC classification are characterized by a long vertical part in the low pressure region. An analysis of isosteric adsorption heats has revealed that lateral interactions among pentane molecules adsorbed on Cu3(BTC)2 dominate over gas–solid interactions. Because there is no equation in the literature, which can be used for the description of isotherms under investigation, equation based on the Dubinin theory of S-shaped adsorption isotherms was developed. According to this theory each adsorbed molecule is a secondary center, which is capable to adsorb other molecules. The equation was suggested with respect to the leveling-off of the isotherms as at the end of the adsorption process the whole adsorption volume becomes filled with adsorbed molecules. Despite only three constants included in the equation, its accuracy in experimental data description is satisfactory.

This study reports the first Co

Zeolite SSZ-33 (topology: CON, borosilicate as-synthesized) contains access to the internal void spaces via 10- and 12-ring pores. Borosilicate SSZ-33 was transformed by isomorphous substitution to Al, Ga and Fe form. The acid sites of zeolite samples were investigated using infrared spectroscopy. The different probes ( d 3 -acetonitrile, pivalonitrile, pyridine and 2,6-di- tert -butyl-pyridine) were used in this study. Bronsted acidity confirms the isomorphous substitution of B by Al, Ga and Fe in the SSZ-33 framework. It was found that the strength of Bronsted acid sites of zeolites under study decreased in the series: [Al]-SSZ-33 > [Ga]-SSZ-33 > [Fe]-SSZ-33. Upon adsorption of 2,6-di- tert -butyl-pyridine a part of Bronsted acid sites was not accessible (51% [Al]-SSZ-33, 76% [Ga]-SSZ-33 and 78% [Fe]-SSZ-33). The catalytic performance was studied in toluene disproportionation and toluene alkylation with isopropyl alcohol. Toluene conversions decreased in the order: [Al]-SSZ-33 > [Ga]-SSZ-33 > [Fe]-SSZ-33 in all tested reactions. Selectivities to sum of xylene isomers in toluene disproportionation was as follows: [Al]-SSZ-33 > [Ga]-SSZ-33 > [Fe]-SSZ-33. Zeolite [Al]-SSZ-33 and [Fe]-SSZ-33 exhibited the highest ratio xylene/benzene 0.75. In the case of toluene alkylation, the highest selectivities to cymenes were achieved over [Fe]-SSZ-33 and [Ga]-SSZ-33 at 200 °C. In the case of [Fe]-SSZ-33 almost no n -propyltoluene was found in the reaction mixture.

Hydrolysis of germanosilicate zeolites with the IWW structure shows two different outcomes depending on the composition of the starting materials. Ge-rich IWW (Si/Ge=3.1) is disassembled into a layered material (IPC-5P), which can be reassembled into an almost pure silica IWW on treatment with diethoxydimethylsilane. Ge-poor IWW (Si/Ge=6.4) is not completely disassembled on hydrolysis, but retains some 3D connectivity. This structure can be reassembled into IWW by incorporation of Al to fill the defects left when the Ge is removed., Angewandte Chemie, 53 (27), ISSN:1521-3757, ISSN:0044-8249

Titanium containing extra-large pore zeolite CIT-5 (IZA code: CFI) was successfully prepared by direct synthesis using Cab-O-Sil M5 and titanium(IV) butoxide in the presence of LiOH. N -Methylsparteinium hydroxide was used as a structure directing agent. The product crystallized into thin plate crystals with an approximate size of 20 × 5 × 0.2 μm. The lowest achieved Si/Ti ratio was 23. The necessary duration of hydrothermal synthesis increased with increasing concentration of Ti in the reaction mixture from 11 days (Si/Ti = 63 in product) to 17 days (Si/Ti = 36) at 155 °C. Prepared Ti-CFI samples exhibit BET surface areas in the range of 308–346 m 2 /g and micropore volumes of 0.094–0.097 cm 3 /g. CFI possesses extra-large pores (14-ring, 7.2 × 7.5 A) accessible for bulky molecules, therefore, Ti-CFI is a useful catalyst for epoxidation of double bonds in bulky molecules used in perfumery and pharmacy. The Ti-CFI samples proved to be catalytically active in epoxidation of 1-octene, cyclooctene, α-pinene, and norbornene with hydrogen peroxide as oxidation agent.

Desilication conditions (concentration of NaOH and TPAOH solution, duration of the treatment) of -SVR zeolite were varied and related to the textural and acidic properties of the obtained materials. The treatment of -SVR zeolite with NaOH solution led to the formation of mesopores and also the increasing of the concentration of surface acid sites, accessible for bulky molecules (e.g. 2,6-ditertbutyl-pyridine). The volume of mesopores as well as the concentration of accessible acid centres in desilicated materials depends mainly on the concentration of the alkaline solution. The increase in the pH of the treatment resulted in moderate decrease of both micropore volume and Bronsted acid sites concentration, while the volume of mesopores increased significantly. Independently of the duration and pH of the treatment with NaOH solution, all desilicated -SVR zeolites are characterized by broad pore-size distribution in the range of 5–20 nm with the maximum around 14 nm. At fixed pH of the treatment with TPAOH, the volume of mesopores and their average size decreased, while the Si/Al ratio and the concentration of Bronsted acid sites in desilicated materials increased which indicates the inhibiting effect of TPA+ cations on the extraction of Si from -SVR zeolite.

Zeolites of different structural types were used as catalysts for aldol condensation of furfural and acetone in batch reaction conditions at T = 20–100 °C and time 0–24 h. To establish a relation between physico-chemical and catalytic properties of microporous materials, the samples were characterized by SEM, N 2 adsorption, FTIR and TGA. It was found that the acidic solids possessed appreciable activity in the reaction and resulted in a formation of products of aldehyde–ketone interaction. Nevertheless, furfural conversion decreased rapidly due to coke formation inside zeolite pores. Simultaneously with a general route of the reaction observed for basic catalysts, dimerization of the condensation product on acidic sites occurred. It was supposed that catalytic behavior of zeolites considerably affected by their both structural and textural properties. Experiments with re-used samples showed that zeolites totally restored their activity and selectivity after calcination at 530 °C.