ZSM-5 aggregates were prepared using a quite small amount of colloidal silicalite-1 as active seed. The obtained ZSM-5 aggregates are well crystallized, possessing large external surface area, mesopore volume, and relatively regular mesopore size distributions. The as-prepared hierarchically porous ZSM-5 aggregates could be directly ion-exchanged to get the acidic H-form zeolite without calcination. When used as catalyst for the LDPE catalytic cracking, the obtained hierarchical ZSM-5 exhibited extinguished catalytic performances. This method for the preparation of hierarchically porous ZSM-5 is much more eco-friendly and cost-effective by avoiding the use of a large amount of organic structure-directing agent and the subsequent combustion of the occluded organic species. It can be easily scaled up and might be of great potential uses in the industrial processes.

We report a tandem asymmetric aldehyde–alkyne–amine (A3) coupling-carboxylative cyclization sequence for the highly enantioselective synthesis of chiral N-aryl 2-oxazolidinones. This is a rare example of a multicatalyst-promoted asymmetric tandem reaction using CO2 as a C1 synthon. Notably, the copper species and ligand from the upstream A3 reaction are internally reused to facilitate the downstream silver-catalyzed carboxylative cyclization.Keywords: 2-oxazolidinone; A3 coupling; asymmetric tandem reaction; carboxylative cyclization; CO2 transformation;

The one-pot reactions of CO2, epibromohydrin, and phenols, thiophenols, or carboxylic acids catalyzed by 1-butyl-3-[(3-hydroxyphenyl)methyl]imidazolium bromide were investigated. Three kinds of cyclic carbonates with ether, thioether, or ester groups were synthesized under mild reaction conditions in good-to-high yields. Reaction-mechanism studies indicated that the proton exchange between the alkoxide formed through the ring-opening reaction of epibromohydrin with 1-bromo-3-phenoxy-2-propanol plays a crucial role in this synthetic route. The catalyst 1-butyl-3-[(3-hydroxyphenyl)methyl]imidazolium bromide was transformed to the corresponding cyclic-carbonate-functionalized ionic liquid during the reaction. This transformation did not affect its catalytic performance in the reaction.

Hierarchically porous ZSM-5 (SiO2/Al2O3 ≈ 120) containing phosphorus was prepared by a one-step post-synthesis treatment involving controlled desilication and phosphorous modification. The hierarchically porous ZSM-5 featured high thermal and hydrothermal stability. The obtained ZSM-5 zeolites were systematically characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption-desorption, NH3 temperature-programmed desorption, and 27Al and 31P magic-angle spinning nuclear magnetic resonance spectroscopy. The prepared ZSM-5 displayed enhanced activity and prolonged lifetime toward hydrocarbon cracking. The high activity was attributed to improved coke tolerance owing to the presence of the highly stable mesoporous network of ZSM-5 and acid sites introduced upon phosphorus modification. Additionally a mechanism of the stabilization of the zeolites by phosphorus was proposed and discussed.Hierarchically porous ZSM-5 with high hydrothermal stability was obtained by a one-step post-synthesis treatment involving simultaneous controlled desilication and phosphorous modification. The prepared catalyst displayed prolonged catalytic activity and stability toward hydrocarbon cracking.Download high-res image (219KB)Download full-size image

Self-assembled mesoporous ZSM-5 microspheres (∼5 μm), which are composed of inter-growthed primary nano-strips, are directly synthesized using n-hexylamine as the single template. The mesopore distribution can be facilely controlled by adjusting the size of primary particles via modulating the alkalinity of the synthesis gel. The samples obtained by varying Na2O/SiO2 molar ratios from 0.07 to 0.15 are denoted as ZM-X (X = 1–5). The ZM-X samples are characterized by techniques including XRD, TEM, SEM, N2 adsorption–desorption and FTIR. It is found that ZM-3 exhibits a uniform mesopore distribution around 10 nm and possesses the largest amount of external acid sites, which lead to the remarkably enhanced catalytic performance in polyolefin cracking. A possible growth mechanism of self-assembled ZSM-5 microspheres directed by n-hexylamine is proposed.

•Phenolic hydroxyl-functionalized imidazolium ionic liquids were synthesized from reaction of imidazole derivatives and alkyl bromides.•The high catalytic activity of ionic liquids in the reaction of CO2 and epoxides attributed to synergistic effect of phenolic hydroxyl and C2-H.•The TOF of IL-2 was 900 h-1 in the reaction of CO2 and epichlorohydrin (in 90% yield) under mild reaction conditions.A series of imidazolium ionic liquids were designed and synthesized by the reaction of imidazole derivatives with alkyl bromides. These ionic liquids were applied to catalyze the reaction of CO2 and epoxides. A detailed investigation was carried out on the relationship between catalytic activities and catalyst structures. The result showed that phenolic hydroxyl-functionalized imidazolium ionic liquids containing both phenolic hydroxyl and C2-H were highly efficient catalysts. Meanwhile, the spatial positions of the phenolic hydroxyl and C2-H in the imidazolium also exhibited great effect on the catalytic efficiencies, and the order of catalytic activity was meta-isomer > ortho-isomer > para-isomer. NMR titration and DFT calculations showed a synergetic effect, which C2-H and phenolic hydroxyl cooperatively activated epoxides by hydrogen bonds, was crucial for the reaction to proceed smoothly under mild conditions. In addition, the TOF of the most active catalyst 3-(3-phenolic hydroxyl)-1-butyl-imidazolium bromide (IL-2) reached to 900 h−1 in the reaction of CO2 and epichlorohydrin under the reaction conditions of 0.1 mol% catalyst, 1 MPa CO2, 120 °C and 1 h.

The polymer-bound Ming-Phos was easily prepared by the highly efficient immobilization of our recently developed Ming-Phos in polystyrene by copolymerization in the presence of 5% DVB, which shows good performance in the application of heterogeneously catalyzed asymmetric cycloaddition. A pair of enantiomers of the product with opposite configurations could be easily delivered in high yields with excellent enantioselectivity by the application of two diastereomers of the heterogeneous catalyst. This heterogeneous catalyst not only exhibits similar catalytic activity and enantioselectivity to those of the homogeneous catalyst but also could be easily recovered and recycled for up to eight cycles.Keywords: cycloaddition; enantioselectivity; gold; heterogeneous catalysis; reuse

Ordered imidazolyl-functionalized mesoporous polymers (IM-MPs) are directly synthesized by an evaporation-induced self-assembly method, which are further functionalized with bromoethane and employed as highly efficient and recyclable catalysts for the cycloaddition of CO2 to epoxides.

A series of novel heterogeneous catalysts were developed by immobilizing imidazolium-based functionalized ionic liquids on an FDU-type mesoporous polymer. Various techniques such as X-ray diffraction, N2 adsorption–desorption, and high resolution transmission electron microscopy were used to characterize the physicochemical properties of the catalysts. Ionic liquid-functionalized mesoporous polymers serve as efficient catalysts in the solvent free cycloaddition reactions of CO2 with epoxides without the use of any co-catalyst. The catalysts can be easily recovered and reused without a significant loss of activity. In comparison with the polystyrene (PS) and mesosilica SBA-15 supports, the FDU mesopolymer possesses both the mesoporous organic framework and abundant phenolic hydroxyl groups, which are key factors in improving the catalytic performance of supported ionic liquids.

A new cinchona alkaloid derived bifunctional tertiary amine-phosphoramide C1e is identified as a highly enantioselective catalyst for Michael addition of both unprotected 3-arylthio- and 3-alkylthiooxindoles to nitroolefins. The phosphoramide moiety of C1e plays an indispensable role in this reaction.

Nu-6(1) zeolite, the lamellar precursor of NSI topology, was firstly synthesized with 4′4-bipyridine as the structure-directing agent (SDA) and then subjected to HCl–EtOH treatment for the purpose of structural modification. Interlayer deconstruction and reconstruction took place alternately in this acid treatment. An intermediate named ECNU-4 was separated at the initial stage of this continuous treatment process, which exhibited a special X-ray diffraction pattern without obvious reflection peaks at low angles. The zeolitic structure in the intralayer sheets was supposed to be well preserved in ECNU-4, whereas the interlayer structure became extremely disordered. The ECNU-4 intermediate showed structural diversity. It was converted into the reconstructed and interlayer expanded zeolite IEZ-NSI without an external silicon source by prolonging the HCl–EtOH treatment to 24 h. Moreover, with a partially delaminated structure, ECNU-4 was easily interlayer swollen at room temperature with cetyltrimethyl ammonium bromide in the presence of tetrapropyl ammonium hydroxide. The swollen material was further sonicated to yield a more deeply delaminated zeolite, Del-Nu-6. ECNU-4 and Del-Nu-6 differed in delamination degree, structural disordering and textural properties, especially surface area.

An interlayer expanded zeolite IEZ-PLS-3 was postsynthesized from the lamellar precursor of PLS-3 aluminosilicate by interlayer silylation with diethoxydimethylsilane (DEDMS) in HCl–EtOH solution at 443 K for 20 h. The resulting material was characterized by various techniques such as XRD, SEM, adsorption of N2, water, and benzene, and IR and NMR spectroscopies, and its catalytic properties were investigated by comparison to those of other zeolites with similar Si/Al ratios in m-xylene isomerization/disproportionation, Friedel–Crafts alkylation of anisole with benzyl alcohol, and acylation of anisole with acetic anhydride. The interlayer expansion created new 12 × 10-membered ring (MR) pores in IEZ-PLS-3. IEZ-PLS-3 showed a larger adsorption capacity of benzene than conventional PLS-3 with 10 × 8-MR channels. In the m-xylene isomerization/disproportionation reaction, IEZ-PLS-3 showed a higher conversion than PLS-3 and gave an isomerization to disproportionation ratio close to that of Beta zeolite, characteristic of shape-selective properties of 12-MR zeolites. IEZ-PLS-3 was more active than Beta in Friedel–Crafts alkylation and acylation reactions, implying that it is a promising solid acid catalyst for processing bulky molecules.

Mesoporous silica nanoparticles (MSNs) are experiencing rapid development in the biomedical field for imaging and for use in heterogeneous catalysis. Although the synthesis of MSNs with various morphologies and particle sizes has been reported, synthesis of a pore network with monodispersion control below 200 nm is still challenging. We achieved this goal using mild conditions. The reaction occurred at atmospheric pressure with a templating sol–gel technique using cetyltrimethylammonium (CTA+) as the templating surfactant and small organic amines (SOAs) as the mineralizing agent. Production of small pore sizes was performed for the first time, using pure and redispersible monodispersed porous nanophases with either stellate (ST) or raspberry-like (RB) channel morphologies. Tosylate (Tos–) counterions favored ST and bromide (Br–) RB morphologies at ultralow SOA concentrations. Both anions yielded a worm-like (WO) morphology at high SOA concentrations. A three-step formation mechanism based on self-assembly and ion competition at the electrical palisade of micelles is proposed. Facile recovery and redispersion using specific SOAs allowed a high yield production at the kilogram scale. This novel technique has practical applications in industry.

Core–shell-structured MWW-type titanosilicate (Ti-MWW) with a well-defined micro-meso hierarchical porosity was fabricated by using self-assembly technique. This composite material Ti-MWW@meso-SiO2 was applied as the catalyst for the ammoximation of cyclohexanone in a continuous slurry reactor. The combination of characterizations, such as XRD, SEM, HR-TEM, and N2 adsorption, verified that the composite material was composed of zeolite crystallites as core and mesosilica as shell and that the micropores and mesopores were penetrated well with each other, which significantly facilitated the diffusion of large molecules. In continuous ammoximation of cyclohexanone as a probe reaction, the composite exhibited significantly prolonged lifetime in comparison to the parent Ti-MWW catalyst and the physical mixture of Ti-MWW and mesosilica. The unique catalytic behaviors of Ti-MWW@meso-SiO2 were ascribed to protecting effect of the mesosilica shell. It served as a sacrificial lamb that protected the active component of zeolite core against rapid desilication and coke formation, leading to a stable duration of the catalysts.Keywords: ammoximation; core−shell structure; cyclohexanone; MWW; titanosilicate; zeolite

Acetaldehyde oxime has been synthesized though the liquid-phase ammoximation of acetaldehyde with ammonia and hydrogen peroxide over various titanosilicate catalysts. Titanium mordenite (Ti-MOR), prepared from highly dealuminated mordenite and TiCl4 vapor by a secondary synthesis method, was superior to TS-1 and Ti-MWW catalysts both in aldehyde conversion and in oxime selectivity. The reaction parameters were investigated systematically in a batch-type reactor for Ti-MOR, such as solvent effect, temperature, time, catalyst loading, amounts of ammonia and hydrogen peroxide relative to aldehyde as well as addition methods of the reactants. Under optimized conditions, Ti-MOR was capable of showing an aldehyde conversion of 99% and an oxime selectivity of 97%. In comparison with TS-1 and Ti-MWW, the advantage of Ti-MOR in acetaldehyde ammoximation was mainly attributed to its lower ability for oxidation to convert the aldehyde to acetic acid. There was almost no effect resulting from the addition mode of the reactants; Ti-MOR with its special characteristics was unique in catalytic behavior and easy handling. An overview of the reaction routes involved in acetaldehyde ammoximation has been provided.

A series of novel heterogeneous olefin metathesis catalysts have been developed by immobilizing Ru species on SBA-15 mesoporous silica with tunable ordered pores and different textural properties. Various techniques such as X-ray diffraction, N2 adsorption–desorption, high resolution transmission electron microscopy have been used to characterize the physicochemical properties of the catalysts. The catalytic activity of thus prepared Ru-based catalysts has been studied in ring closing metathesis (RCM) and other metathesis reactions. Among these immobilized catalysts, the SBA-15 support with the largest pore size gives rise to the highest catalytic activity because the large pores are benefit for the diffusion of reactants and products. The immobilized Ru catalysts prove to be reusable in RCM reactions. Their catalytic activity is closely related to the confinement effect and high hydrophobicity of SBA-15 mesopores.Graphical abstractHighlights► New heterogeneous olefin metathesis catalysts are prepared. ► The Grubbs catalysts are immobilized on SBA-15 mesosilica. ► The immobilized Grubbs catalysts are effective and reusable in RCM and CM reactions.

Ni(ClO4)2·6H2O-catalysed regioselective and diastereoselective [3+2]-annulations of aryl oxiranyl-dicarboxylates and indolesvia selective C–C bond cleavage of oxirane were revealed. The cycloadditions proceed smoothly with high regio- and diastereoselectivity under mild conditions leading to 1H-furo[3,4-b]indoles in good to excellent yields.

Micro-/mesoporous composite materials that possessed core–shell structure were prepared through oriented assembly of mesoporous silica on premade titanosilicate zeolite TS-1 using triblock copolymer surfactant P123 as template in an acid-free system. When the pH value of P123/NaCl/H2O/EtOH/TEOS/TS-1 synthetic system was controlled in the range of 3.5–5.5, the crystalline particles of TS-1 were negatively charged, whereas P123 micelles were partially protonated. Thus induced an electrostatic interaction between inorganic zeolite and organic micelles probably via enhanced hydrogen bonding, and made an oriented assembly of silica oligomer or silica-micelle composite on the surface of P123/TS-1 and further condensation. Otherwise, the silica was self-assembled in a phase separation manner, or failed to form a mesophase. The mesopores in silica shell were of wormhole-like and interconnected with the micropores in TS-1. When as-synthesized core/shell composites were hydrothermally post-treated, the pore volume, specific surface area and pore size of shell increased with increasing temperature. The average shell thickness and particle size were conveniently adjusted in the range of 30–90 nm and 350–500 nm, respectively, by changing the synthesis time, temperature, and amount of silica source added.Graphical abstractHighlights► Core–shell structured TS-1@mesosilica was prepared using triblock copolymer. ► The thickness of mesosilica shell was adjustable in the range of 30–90 nm. ► The electrostatic interaction is essential to induce an oriented assembly of mesosilica shell.

Hierarchically ordered materials with core/shell structures were synthesized through a layer-by-layer approach. The novel microporous/mesoporous hybrid materials were composed of a TS-1 zeolite particle for the core and mesoporous silica for the shell. The as-synthesized TS-1 crystals were modified with polydiallyldimethylammonium chloride to make their external surface positively charged, which induced an oriented self-assembly of tetraethoxysilane (TEOS) with cetyltrimethyl ammonium bromide on the TS-1 particle surface to form a shell of mesophase silica. The thickness of the mesoporous silica shell was controlled to be in the range 30–55 nm by changing the amount of TEOS added in the synthesis. The mesoporous channels in the shell were perpendicular to the zeolite core, which made the micropores inside the core accessible from the outside through the mesopores. Taking advantage of the confining effect of the mesopores, Au nanoparticles were incorporated into the shell, resulting in bifunctional catalysts which were more selective than conventional Au/TS-1 catalysts in the direct epoxidation of propylene to propylene oxide with H2 and O2.

High-silica mordenite (MOR) zeolites were hydrothermally synthesized by a dual-templating method using tetraethylammonium hydroxide (TEAOH) and hexamethyleneimine (HMI) as co-structure-directing agents (SDAs). The MOR zeolites were crystallized readily with the addition of NH4NO3 from the gels that had a Si/Al ratio up to 60. The synthesis resulted in highly crystalline MOR zeolites possessing a Si/Al ratio of 37.1. The chemical coordination states of the Al ions in the MOR zeolites were characterized by 27Al and 29Si NMR MAS spectroscopy. The Al ions occupied dominantly the tetrahedral sites in the framework. The dual-templating effect that the two amines exhibited on the zeolite crystallization was investigated by 13C MAS NMR spectroscopy and elemental analyses. Both organic SDA molecules were incorporated simultaneously into the zeolite products, corresponding to 65% of TEA+ and 35% of HMI. These two kinds of SDAs played a cooperative role in the nucleation and crystallization of the MOR structure under high silica conditions.Graphical abstractHighlights► High-silica mordenite (MOR) zeolites were synthesized with a dual-templating method. ► The synthesis was carried out with the assistant of seeding crystals in the absence of fluoride media. ► Pure MOR phase was obtained from the synthetic gels with a Si/Al ratio up to 60. ► The Si/Al ratio of MOR product reaches 37.1. ► Two amines show a cooperative role in the crystallization of MOR.

Nanosized Beta zeolites were postsynthetically modi-fied through the solid−gas reaction of highly dealuminated Beta zeolite with SnCl4 vapor at elevated temperatures. The incorporation mechanism of Sn ions and the physicochemical properties of resultant Sn-Beta-PS were characterized by various techniques. Its catalytic performance in Baeyer−Villiger oxidation was compared with the micrometer-sized Sn-Beta-F hydrothermally synthesized by conventional fluoride method. The Sn species were inserted into the framework via the reaction of the SnCl4 molecules with the silanols in the hydroxyl nests that were created by dealumination and thus occupied predominately the tetrahedral coordination sites. The Sn content gained by postsynthesis reached up to 6.2 wt %, corresponding to a Si/Sn ratio of ca. 35. The isolated Sn species exhibited Lewis acidity useful for the Baeyer−Villiger oxidation of ketones. Containing higher Sn contents and more importantly proposing less diffusion limitations to the substrates with a large molecular dimension, nanosized Sn-Beta-PS was superior to Sn-Beta-F in the selective oxidation of 2-adamantanone with hydrogen peroxide.

FDU-15-SO3H, a solid acid material prepared from the sulfonation of FDU-15 mesoporous polymer, has been demonstrated to serve as an efficient catalyst in the esterification of palmitic acid with methanol as well as in the transesterification of fatty acid-edible oil mixture. FDU-15-SO3H achieved an acid conversion of 99.0% when the esterification was carried out at 343 K with a methanol/palmitic acid molar ratio of 6:1 and 5 wt% catalyst loading. It was capable of giving 99.0% yield of fatty acid methyl esters (FAME) when the transesterification of soybean oil was performed at 413 K and the methanol/oil weight ratio of 1:1. FDU-15-SO3H was further applied to the transesterification/esterification of the oil mixtures with a varying ratio of soybean oil to palmitic acid, which simulated the feedstock with a high content of free fatty acids. The yield of FAME reached 95% for the oil mixtures containing 30 wt% palmitic acid. This indicated the sulfonated mesopolymer was a potential catalyst for clean synthesis of fuel alternative of biodiesel from the waste oil without further purification.

•Mesoporous ZSM-5 was prepared using 1, 6-diaminohexane (HDA) and CTABr.•Competition of HDA and CTABr was effectively avoided.•Ordered mesoporous silica-alumina species formed firstly at the convenience of CTABr.•It transformed in-situ to the hierarchical ZSM-5 aggregates with assistance of HDA.•This method is facile and cost-effective, applicable in a wide SiO2/Al2O3 ratio range.Hierarchical ZSM-5 aggregates were fabricated using the conventional surfactant cetyltrimethylammonium bromide (CTABr) as the mesoporogen together with 1, 6-diaminohexane (HDA) as structure-directing agent. The competition of the templates and the subsequent phase separation were effectively avoided. A possible formation mechanism was proposed based on the investigation of the crystallization process. The obtained hierarchical ZSM-5 aggregates were highly crystallized, possessing large external surface area, mesopore volume and regular mesopore size distributions. And they were proved to be more efficient in catalytic LDPE cracking due to improved accessibility of large polymer molecules to the active sites. This method was facile and cost-effective, applicable within a wide SiO2/Al2O3 ratio by using various silica sources.Hierarchical ZSM-5 with large external surface area, secondary pore volume and regular mesopore size distribution was fabricated through the in-situ conversion of the order mesoporous silica-alumina species, exhibiting the excellent performance when LDPE catalytic cracking was used as the probe reaction.

•Silicate-2 aggregates (> 5 μm) were aluminated.•The aluminated aggregates possess open porosity and low Brønsted/Lewis acid ratio.•Modified acidity and porosity increased catalyst lifetime in MTH process.Aluminated hierarchical silicalite-2 with both large particle size and high external surface area was prepared by aluminating silicalite-2 under the protection of TBA+ cations in a mild alkaline solution. The textural and acidic properties of thus formed material (Z11-meso) were characterized by SEM, TEM, XRD, N2 adsorption, FTIR, NH3-TPD, and 27Al NMR spectroscopy. The resulting hierarchical Z11-meso contained mainly tetrahedral coordinated aluminum species with low Brønsted/Lewis ratio (B/L) while preserved the zeolitic structure. Owning to the high external surface area (Sext), hierarchical porous structures and low B/L ratio, Z11-meso outperformed the microporous ZSM-11 counterparts in methanol to hydrocarbons in terms of both activity and stability.Download high-res image (201KB)Download full-size image

A shape-selective core/shell-structured Al-MWW@B-MWW composite catalyst has been hydrothermally synthesized through isomorphically overgrowing borosilicate on premade MCM-22 aluminosilicate. The secondary growth of borosilicate enlarged obviously the thickness of the platelet crystallites of MCM-22 and increased the surface Si/Al ratio from 16 to 222. The Fourier transform infrared (FTIR) spectra of adsorbed 2,6-di-tert-butylpyridine indicated that the Brønsted acid sites located on the external surface were virtually covered completely by the generated B-MWW layer, whereas those acid sites within channels were still accessible and detectable by using pyridine or ammonia as probing molecules. When applied to the disproportionation of toluene on a fixed-bed reactor, the Al-MWW@B-MWW composite catalysts exhibited significantly enhanced para-xylene selectivity in comparison with normal MCM-22 and its physical mixture with B-MWW. Al-MWW@B-MWW’s unique catalytic behaviors were ascribed to an effective suppression of para-xylene isomerization as a result of removal of non-shape-selective acid sites on the external surface.Graphical abstractCore/shell-structured MWW-type zeolites prepared by isomorphic overgrowth of borosilicate on premade MCM-22 crystallites are highly shape-selective materials for the disproportionation of toluene as a result of suppressing the isomerization of para-xylene on the external surface of crystallites.Download high-res image (190KB)Download full-size imageHighlights► Isomorphic overgrowth of borosilicate on MCM-22 leads to a core/shell-structured zeolite. ► Secondary growth of borosilicate removes the strong acid sites on the external surface. ► Al-MWW@B-MWW is highly shape selective to toluene disproportionation. ► The removal of surface acidity suppresses the isomerization of para-xylene on the crystallite surface.

Mesoporous titanosilicate with the MOR topology, denoted as Ti-Meso-MOR, was postsynthesized from commercially available mordenite by sequential acid, alkaline, acid, and TiCl4 vapor treatments, and its catalytic oxidation properties were investigated in detail in liquid-phase oxidation reactions with hydrogen peroxide as an oxidant. A controllable acid leaching was first carried out on H-mordenite (Si/Al = 7.8) to induce a partial dealumination to Si/Al = 80, which was suitable for constructing secondary mesopores by subsequent alkaline treatment. Alkaline treatment-induced desilication introduced a large number of intracrystal mesopores. Tetracoordinated Ti species were then inserted into the resultant mesoporous mordenite with a high dealumination degree (Si/Al = 145) through the gas–solid reaction with TiCl4 vapor at elevated temperatures. In comparison with conventional Ti-MOR and TS-1, Ti-Meso-MOR thus prepared exhibited an improved catalytic activity in the hydroxylation of toluene and the ammoximation of cyclohexanone as well. Moreover, Ti-Meso-MOR proved to be a robust catalyst for continuous ammoximation since the mesopores minimized diffusion limitation and suppressed coke formation efficiently.Graphical abstractMesoporous titanosilicate with the MOR topology, postsynthesized by sequential dealumination, desilication, and TiCl4 vapor treatment, are highly active for the liquid-phase ammoximation of cyclohexanone and hydroxylation of toluene with hydrogen peroxide as oxidant.Download high-res image (139KB)Download full-size imageHighlights► MOR-type aluminosilicate was converted into mesoporous zeolite by post-desilication. ► Tetrahedral Ti species were incorporated into the Al-deficient sites by secondary synthesis, leading to mesoporous titanosilicate, Ti-Meso-MOR. ► Possessing an improved accessibility to Ti active sites, Ti-Meso-MOR is highly active for the liquid-phase oxidations with hydrogen peroxide.

Ordered imidazolyl-functionalized mesoporous polymers (IM-MPs) are directly synthesized by an evaporation-induced self-assembly method, which are further functionalized with bromoethane and employed as highly efficient and recyclable catalysts for the cycloaddition of CO2 to epoxides.

Ni(ClO4)2·6H2O-catalysed regioselective and diastereoselective [3+2]-annulations of aryl oxiranyl-dicarboxylates and indolesvia selective C–C bond cleavage of oxirane were revealed. The cycloadditions proceed smoothly with high regio- and diastereoselectivity under mild conditions leading to 1H-furo[3,4-b]indoles in good to excellent yields.

A new cinchona alkaloid derived bifunctional tertiary amine-phosphoramide C1e is identified as a highly enantioselective catalyst for Michael addition of both unprotected 3-arylthio- and 3-alkylthiooxindoles to nitroolefins. The phosphoramide moiety of C1e plays an indispensable role in this reaction.

Hierarchically ordered materials with core/shell structures were synthesized through a layer-by-layer approach. The novel microporous/mesoporous hybrid materials were composed of a TS-1 zeolite particle for the core and mesoporous silica for the shell. The as-synthesized TS-1 crystals were modified with polydiallyldimethylammonium chloride to make their external surface positively charged, which induced an oriented self-assembly of tetraethoxysilane (TEOS) with cetyltrimethyl ammonium bromide on the TS-1 particle surface to form a shell of mesophase silica. The thickness of the mesoporous silica shell was controlled to be in the range 30–55 nm by changing the amount of TEOS added in the synthesis. The mesoporous channels in the shell were perpendicular to the zeolite core, which made the micropores inside the core accessible from the outside through the mesopores. Taking advantage of the confining effect of the mesopores, Au nanoparticles were incorporated into the shell, resulting in bifunctional catalysts which were more selective than conventional Au/TS-1 catalysts in the direct epoxidation of propylene to propylene oxide with H2 and O2.

Nu-6(1) zeolite, the lamellar precursor of NSI topology, was firstly synthesized with 4′4-bipyridine as the structure-directing agent (SDA) and then subjected to HCl–EtOH treatment for the purpose of structural modification. Interlayer deconstruction and reconstruction took place alternately in this acid treatment. An intermediate named ECNU-4 was separated at the initial stage of this continuous treatment process, which exhibited a special X-ray diffraction pattern without obvious reflection peaks at low angles. The zeolitic structure in the intralayer sheets was supposed to be well preserved in ECNU-4, whereas the interlayer structure became extremely disordered. The ECNU-4 intermediate showed structural diversity. It was converted into the reconstructed and interlayer expanded zeolite IEZ-NSI without an external silicon source by prolonging the HCl–EtOH treatment to 24 h. Moreover, with a partially delaminated structure, ECNU-4 was easily interlayer swollen at room temperature with cetyltrimethyl ammonium bromide in the presence of tetrapropyl ammonium hydroxide. The swollen material was further sonicated to yield a more deeply delaminated zeolite, Del-Nu-6. ECNU-4 and Del-Nu-6 differed in delamination degree, structural disordering and textural properties, especially surface area.

Acetaldehyde oxime has been synthesized though the liquid-phase ammoximation of acetaldehyde with ammonia and hydrogen peroxide over various titanosilicate catalysts. Titanium mordenite (Ti-MOR), prepared from highly dealuminated mordenite and TiCl4 vapor by a secondary synthesis method, was superior to TS-1 and Ti-MWW catalysts both in aldehyde conversion and in oxime selectivity. The reaction parameters were investigated systematically in a batch-type reactor for Ti-MOR, such as solvent effect, temperature, time, catalyst loading, amounts of ammonia and hydrogen peroxide relative to aldehyde as well as addition methods of the reactants. Under optimized conditions, Ti-MOR was capable of showing an aldehyde conversion of 99% and an oxime selectivity of 97%. In comparison with TS-1 and Ti-MWW, the advantage of Ti-MOR in acetaldehyde ammoximation was mainly attributed to its lower ability for oxidation to convert the aldehyde to acetic acid. There was almost no effect resulting from the addition mode of the reactants; Ti-MOR with its special characteristics was unique in catalytic behavior and easy handling. An overview of the reaction routes involved in acetaldehyde ammoximation has been provided.