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We report a method to prepare core-shell zeolite beta (*BEA) with an aluminous core and an epitaxial Si-rich shell. This method capitalizes on the inherent defects in *BEA crystals to simultaneously passivate acid sites on external surfaces and increase intracrystalline mesoporosity through facile post-hydrothermal synthesis modification in alkaline media. This process creates more hydrophobic materials by reducing silanol defects and enriching the shell in silica via a combination of dealumination and the relocation of silica from the core to the shell during intracrystalline mesopore formation. The catalytic consequences of *BEA core-shells relative to conventional analogues were tested using the biomass conversion of levulinic acid and n-butanol to n-butyl levulinate as a benchmark reaction. Our findings reveal that siliceous shells and intracrystalline mesopores synergistically enhance the performance of *BEA catalysts. This work was supported by BASF Corporation. Additional support for JDR was provided by The Welch Foundation (Award E-1794). ToF-SIMS analysis was carried out with support provided by the National Science Foundation CBET-1626418. This work was conducted in part using resources of the Shared Equipment Authority at Rice University. JGM received funding for this project from the European Union’s Horizon 2020 research and innovation program under grant agreement No 872102. JGM and NL thank the Spanish Ministry of Science and Innovation and AEI/FEDER, UE through the project ref. RTI2018-099504-B-C21. NL acknowledges additional support from the University of Alicante (UATALENTO17-05).

Intracrystalline mesoporosity can be conveniently introduced in zeolites using cationic surfactants in a mild basic solution –a process known as surfactant-templating. However, this technique is limited to small-headed and single-chain surfactants because they need to diffuse through the narrow micropores of the zeolite, which limits the potential of this approach. Herein, we show that the mesoporosity generated in zeolites with small-headed and single-chain surfactants, such as CTAB, provides enough accessibility to allow the use of bulky surfactants that otherwise cannot enter the structure of the zeolite. Moreover, in this contribution, a USY zeolite has been successively treated with cationic surfactants of different chain lengths (C12 to C22) proving that the mesopores introduced in the zeolite can be efficiently widened and narrowed by consecutive treatments with surfactants of the suitable size. Finally, the use of consecutive surfactant-templating opens up the possibility of using surfactants of different packing parameters to produce new hierarchical architectures in zeolites. The authors thank the synchrotron ALBA (2018022824) and Spanish MINECO-AEI/FEDER (CTQ2015-74494-JIN and RTI2018-099504-B-C21). E. Serrano and N. Linares acknowledges the University of Alicante (refs UATALENTO 16-03 and 17-05, respectively).

A mild alkaline treatment with the assistance of surfactants has proved to be an effective way to introduce uniform mesopores into zeolites, yielding hierarchical materials with superior catalytic performance. Accelerating this process may open new opportunities in the scale-up of this new class of materials. In this study, we present an ultrafast surfactant-templating (UST) approach achieved within only a few minutes for the fast production of mesoporous ultra-stable Y (USY) zeolites by combining several favorable factors including high treating temperature, reactors featuring fast heating, and optimized reagent composition. Temperatures in the range of 150–220 °C yielded high quality materials, while too high temperatures (260–280 °C) produced inferior samples. The use of a flow reactor allowed for completing the UST in just one minute, which evidences the remarkable structural flexibility of zeolites that can reorganize in such a short time to accommodate a large amount of intracrystalline mesoporosity, without compromising their integrity or main properties. C. P. is grateful to the Chinese Scholarship Council and the Ministry of Education, Culture, Sports, Science and Technology, Japan for a MonbuKagakusho Scholarship. N. L. acknowledges funding from the University of Alicante, through the “Programa de captación y retención de talento” (ref. UATALENTO17-05). C. A Trujillo acknowledges the Universidad Nacional de Colombia and Ecopetrol for the support of the Laboratorio de Catálisis Heterogénea. Z. L. acknowledges the Japan Society for the Promotion of Science (JSPS) for financial support (a Grant-in-Aid for Young Scientists: 18K14049).

Micelle formation inside faujasite (FAU) zeolite, a critical step in the introduction of mesoporosity in zeolites by surfactant templating, has been confirmed by both 13C NMR and Raman spectroscopy. Here we provide unambiguous evidence of the incorporation of surfactant molecules inside zeolites during the first step of the surfactant-templating process followed by their self-assembly into micelles after hydrothermal treatment. The homogeneous presence of these micelles throughout zeolite crystals has been directly observed by Raman microspectroscopy, confirming the uniform incorporation of mesoporosity in zeolites by surfactant templating. We thank the European Commission for funding through the H2020-MSCA-RISE-2019 program (ref. ZEOBIOCHEM - 872102) and the Spanish MINECO and AEI/FEDER, UE through the project ref RTI2018-099504-B-C21. N.L. acknowledges the University of Alicante support (UATALENTO17-05). M.J.M.-C. thanks the Generalitat Valenciana for a Ph.D. fellowship (GRISOLIAP/2020/165). M.B.J.R. acknowledges financial support from the FWO for the investment in microscopy (AKUL/15/15 - G0H0816N and G0H6316N - ZW15_09) and financial support from the KU Leuven Research Fund (C14/19/079).

Tailoring processes of nucleation and growth to achieve desired material properties is a pervasive challenge in synthetic crystallization. In systems where crystals form via nonclassical pathways, engineering materials often requires the controlled assembly and structural evolution of colloidal precursors. In this study, we examine zeolite SSZ-13 crystallization and show that several polyquaternary amines function as efficient accelerants of nucleation, and, in select cases, tune crystal size by orders of magnitude. Among the additives tested, polydiallyldimethylammonium (PDDA) was found to have the most pronounced impact on the kinetics of SSZ-13 formation, leading to a 4-fold reduction in crystallization time. Our findings also reveal that enhanced nucleation occurs at an optimal PDDA concentration where a combination of light scattering techniques demonstrate these conditions lead to polymer-induced aggregation of amorphous precursors and the promotion of (alumino)silicate precipitation from growth solution. Here, we show that relatively low concentrations of polymer additives can be used in unique ways to dramatically enhance SSZ-13 crystallization rates, thereby improving the overall efficiency of zeolite synthesis. JDR received financial support primarily from BASF Corporation along with additional support from the Welch Foundation (Award E-1794). JGM received financial support from the European Commission through the H2020-MSCA-RISE-2019 program (Award ZEOBIOCHEM – 872102) and the Spanish MINECO and AEI/FEDER, UE through Award RTI2018-099504-B-C21. NL acknowledges the University of Alicante support (Award UATALENTO17-05).

A hierarchical USY zeolite has been produced using the surfactant-templating method and used as a catalyst for the production of two important active pharmaceutical ingredients. The presence of intracrystalline mesoporosity in the zeolite results in a significant increase in both the activity (up to 30 fold increase in TOF) and reusability for Friedel–Crafts alkylation and aldol condensation steps. N. L. wishes to thank the Generalitat Valenciana for financial support under the project BEST/2018/039 and the University of Alicante, through the “Programa de captación y retención de talento” (UATALENTO17-05).

Conventional methods to prepare hierarchical zeolites depend upon the use of organic structure‐directing agents and often require multiple synthesis steps with limited product yield and Brønsted acid concentration. Here, it is shown that the use of MEL‐ or MFI‐type zeolites as crystalline seeds induces the spontaneous formation of self‐pillared pentasil zeolites, thus avoiding the use of any organic or branching template for the crystallization of these hierarchical structures. The mechanism of formation is evaluated by time‐resolved electron microscopy to provide evidence for the heterogeneous nucleation and growth of sequentially branched nanosheets from amorphous precursors. The resulting hierarchical zeolites have large external surface area and high percentages of external acid sites, which markedly improves their catalytic performance in the Friedel–Crafts alkylation and methanol to hydrocarbons reactions. These findings highlight a facile, commercially viable synthesis method to reduce mass‐transport limitations and improve the performance of zeolite catalysts. J.D.R. acknowledges support primarily from the U.S. Department of Energy Office of Basic Energy Sciences (Award DE-SC0014468). J.D.R. acknowledges additional funding from the Welch Foundation (Award E-1794). N.L and J.G.M thank the European Commission for funding through the H2020-MSCARISE-2019 program (Ref. ZEOBIOCHEM – 872102) and the Spanish MINECO and AEI/FEDER, UE through the project ref. RTI2018-099504-B-C21. N.L. also acknowledges the University of Alicante support (UATALENTO17-05).

A method to produce hybrid organotitanias, both as thin films and suspensions, showing excellent photocatalyic activity in the degradation of organic dyes in aqueous solutions under visible light irradiation is disclosed. This method is based on the in situ incorporation of an amino acid, l-tyrosine, during the synthesis of the titanias owing to its coordination and co-condensation with the titania precursor under acidic conditions. This methodology allows the fine -tuning of their crystalline structure, size, and shape by simply varying the pH of the synthesis gel, leading to anatase nanoparticles of ≈5 nm and surface areas of ≈200 m2 g−1 at pH = 2.2, while highly crystalline rutile nanorods are formed at pH = 0. The incorporation of l-tyrosine to both anatase nanoparticles and rutile nanorods enables these materials to absorb light in the visible range due to both the decrease in their band gap, as compared to the reference materials, and the presence of additional absorption edges at wavelengths higher than 400 nm. Consequently, the photocatalytic activity of both hybrid anatase nanoparticles and rutile nanorods exhibits a 120% enhanced photocatalytic efficiency, as compared to that of l-Tyr-free titanias and the commercial P25, which confirms their potential application in water remediation. This work was supported by the Ministerio de Ciencia en Innovación of Spain (MICINN) and Agencia Estatal de Investigación (AEI)/European Regional Development Fund (FEDER) (projects CTQ2015-74494-JIN and RTI2018-099504-B-C21/A-C22). N.L. and E.S. also thank the Universidad de Alicante (Spain) through the “Programa de Retención de Talento” (ref. UATALENTO16-03 and 17-05, respectively).

This work presents the first biphasic brookite–rutile organotitania, TiO2(B,R)–Phen, synthesized by a sol–gel method, under mild conditions and using 1,10-phenanthroline (Phen) as a crystal modifier and as a source of intermediate N2p states. Phen is able to coordinate to the Ti(IV) atom of the titanium alkoxide precursor, tetrabutyl orthotitanate (TBOT), forming an organotitania precursor that leads to the formation of a binary brookite–rutile structure, instead of the typical anatase. Different from the nitrogen-doped titanias, in which the N2p levels form due to the presence of N atoms in the O lattice position of the titania crystal, the coordination between the Ti atom of the titania precursor and Phen is maintained during the whole synthetic process, which is responsible for the presence of intermediate N2p states related to Ti–N bonds in the final materials, which is key to activating the photocatalysis behavior under visible light. Both features allow the simultaneous reduction of charge recombination rate and enhancement of photo-induced electron transfer in the visible range. Indeed, a 10-fold increase in the photocatalytic rate constant along with enhanced stability for the degradation of cationic dyes in aqueous solutions under visible light was noted in stark comparison with reference titanias. The photocatalysis mechanism consists of the self-degradation of the dyes, while the enhanced photoactivity results from a combination of the binary brookite–rutile structure and the blue absorption Ti–N states. As such, this work presents a unique synthesis strategy to obtain biphasic brookite–rutile organotitanias bearing Ti-N bonds that exhibit superior photocatalytic degradation activity of pollutants in aqueous solutions using visible light. This work was supported by the Spanish MICINN and AEI/FEDER (projects CTQ2015-74494-JIN and RTI2018-099504-BC21/A-C22). E. S. and N. L. also thank the University of Alicante for the “Programa de Retención de Talento” (ref. UATALENTO16-03 and 17-05, respectively). I. G. P and R. D. C. acknowledge the program “Ayudas para la atracción de talento investigador – Modalidad 1 of the Consejería de Educación, Juventud y Deporte – Comunidad de Madrid with reference number 2016-T1/IND-1463”. R. D. C. also acknowledges the Spanish MINECO for the Ramon y Cajal program (RYC-2016-20891), and HYNANOSC (RTI2018-099504-A-C22). R. D. C. also acknowledges the FOTOART-CM project funded by the Madrid region under program P2018/NMT-4367.

A large number of inorganic and organic materials have been postulated to grow via nonclassical pathways involving the assembly of amorphous precursors that serve as growth units for crystallization. Elucidating the assembly, microstructure, and mechanism(s) by which precursors are involved in processes of nucleation and growth is nontrivial because of the lack of available techniques that are capable of monitoring amorphous-to-crystal transformations with sufficient spatiotemporal resolution. Here we propose an elemental mapping method employing field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FE-SEM-EDX) as a versatile tool to characterize morphological and compositional properties of precursors during the crystallization of five zeolites (MER, MFI, MOR, TON, and LTL) that are used in commercial applications that include (but are not limited to) catalysis, ion exchange, separations, drug delivery, and adsorption. Time-resolved ex situ elemental mapping images of extracted solids during several stages of zeolite crystallization reveal that a sufficient disparity in the chemical composition (e.g., alkali metal content) between amorphous precursors and crystals can be exploited for (i) tracking the early stages of zeolite crystallization, (ii) locating where it happens, and (iii) resolving residual amorphous material among crystalline domains. In this study, we also show that FE-SEM-EDX elemental mapping is a highly sensitive technique to detect the onset of nucleation, the completion of crystallization, and the existence of impurities. Given the ubiquitous presence of amorphous precursors during nonclassical crystallization, we expect that elemental mapping may prove valuable for understanding and tracking the growth of other zeolites, minerals, and related materials. J.D.R. acknowledges funding from the Welch Foundation (Award E-1794). J.G.M. and N.L. acknowledge funding from the Spanish Ministry of Science and Innovation (RTI2018-099504-B-C21). N.L. acknowledges funding from the University of Alicante (UATALENTO17-05).

Mesopores in the range of 4 to 5 nm were introduced into zeolite Y (nSi/nAl = 16) by surfactant-templating. This method using a mixture of octadecyltrimethylammonium hydroxide and bromide (C18TAOH/C18TABr) yields a mesoporous zeolite (Y–C18TAOH) with a higher specific mesopore volume and only a small loss in crystallinity and specific micropore volume. After loading with Pt, the two bifunctional catalysts (2.7Pt/Y and 2.6Pt/Y–C18TAOH) were applied in the aqueous-phase hydrogenation of levulinic acid (LA) to γ–valerolactone (GVL) (pH2 = 2.5 MPa, 393 K). Intraparticle mass–transfer limitations present for the catalyst 2.7Pt/Y were not observed in the LA hydrogenation over the catalyst with the hierarchical pore system 2.6Pt/Y–C18TAOH. Changes in the acid and de-/hydrogenation functionality are shown not to be responsible for the high catalytic activity of 2.6Pt/Y–C18TAOH. The presence of additional mesopores in a bifunctional catalyst based on zeolite Y is proven to enhance the mass-transfer properties and the resulting catalytic activity in the aqueous-phase hydrogenation of LA for the first time. Hue-Tong Vu is grateful to Vietnam International Education Development of the Ministry of Education and Training, Vietnam, for funding her doctoral study at Universität Leipzig, Germany. Noemi Linares and Javier García-Martínez acknowledge funding from the European Commission through the H2020-MSCA-RISE-2019 program (Ref. ZEOBIOCHEM – 872102) and the Spanish MINECO and AEI/FEDER, UE through the project RTI2018-099504-B-C21. Noemi Linares thanks the University of Alicante for funding (UATALENTO17-05).

The assembly and structural evolution of amorphous precursors during zeolite crystallization is an important area of interest owing to their putative roles in the nucleation and growth of aluminosilicate microporous materials. Precursors range in complexity from oligomeric molecules and colloidal particles to gels comprised of heterogeneous silica and alumina domains. The physical state of precursors in most zeolite syntheses is generally not well understood; however, it is evident that the physicochemical properties of precursors depend on a wide range of conditions that include (but are not limited to) the selection of reagents, the composition of growth mixtures, the methods of preparation, and the use of inorganic and/or organic structure-directing agents. The fact that precursors evolve in size, shape, and/or microstructure during the course of nucleation and potentially throughout crystallization leads to questions pertaining to their mode of action in the formation of zeolites. This also highlights...

Novel insights into the surfactant-templating process leading to the formation of tailored intracrystalline mesoporosity in USY zeolite are presented in the light of the changes in the textural, morphological, and chemical properties of this zeolite produced during its treatment in a basic solution of cetyltrimethylammonium bromide (CTAB). The inability of analogous surfactants with bulkier heads to produce mesoporosity suggests that individual CTAB molecules can actually enter the zeolite through its microporosity. Once inside, the surfactant molecules self-assemble to produce the micelles responsible for the formation of mesoporosity causing the expansion of the zeolite crystals, as evidenced by He pycnometry measurements. The analysis of ultramicrotomed samples by transmission electron microscopy evidenced the formation of uniform intracrystalline mesoporosity throughout the entire crystals. In order to investigate an alternative method, namely, the dissolution and reassembly of zeolites, this was performed in USY leading to the formation of composite materials, which are distinctly different from the zeolite with intracrystalline mesoporosity obtained by surfactant-templating. Finally, it was proved that the presence of mesoporosity in the initial zeolite is not needed for the surfactant-templating to occur. This was verified by surfactant-templating of a NaY zeolite, which does not present the large mesopores found in USY. Authors acknowledge the CAPITA project WAVES (EP7-NMP-266543) and Rive Technology for financial support.

The development of intracrystalline mesoporosity within zeolites has been a long-standing goal in catalysis as it greatly contributes to alleviating the diffusion limitations of these widely used microporous materials. The combination of in situ synchrotron X-ray diffraction and liquid-cell transmission electron microscopy enabled the first in situ observation of the development of intracrystalline mesoporosity in zeolites and provided structural and kinetic information on the changes produced in zeolites to accommodate the mesoporosity. The interpretation of the time-resolved diffractograms together with computational simulations evidenced the formation of short-range hexagonally ordered mesoporosity within the zeolite framework, and the in situ electron microscopy studies allowed the direct observation of structural changes in the zeolite during the process. The evidence for the templating and protective role of the surfactant and the rearrangement of the zeolite crystal to accommodate intracrystalline mesoporosity opens new and exciting opportunities for the production of tailored hierarchical zeolites. We acknowledge the ALBA synchrotron for beamtime availability (Project ID: 2015021271) and the Center for Functional Nanomaterials at the Brookhaven National Laboratory for the Liq-TEM availability. The authors further acknowledge the CAPITA Project WAVES (EP7-NMP-266543) for financial support.

With the aim of understanding the thermochemistry of the introduction of mesoporosity in zeolites by using surfactants, high temperature oxide melt solution calorimetry was used to determine the change in the enthalpy of formation of USY zeolite before and after the introduction of mesoporosity. Our results confirm that this process only slightly destabilizes the zeolite by the additional surface area. However, this can be overcome by the stabilizing effect of the interactions between the surfactant and the zeolite framework. N.L. and E.S. acknowledge the University of Alicante support through the “Programa de retención y captación de talento” (ref. UATALENTO17-05 and UATALENTO16-03, respectively). The calorimetry at UC Davis was supported by the U.S. Department of Energy grant DE-SC0016573. We also thank the Spanish MINECO and AEI/FEDER (ref. CTQ2015-7449-JIN) for funding.

The treatment of zeolites with surfactants in alkaline media is an effective and versatile technique to impart intracrystalline well-defined mesoporosity in these materials. In this study, the dynamics of surface reconstruction that occurs during the treatment of USY zeolite by surfactant-templating was monitored in situ by atomic force microscopy. The development of surfactant-templated mesoporosity and the concurrent healing of defects that are characteristic of steamed zeolites occur in less than 1 h at room temperature, which emphasizes the low energy barriers needed to reorganize the crystalline structure of this zeolite. This transformation was also followed by X-ray diffraction, N2 adsorption, and transmission electron microscopy analysis of ultramicrotomed samples to confirm that the rapid formation of surfactant-templated mesoporosity and the reconstruction of the zeolite crystals occur not only on the surface of the zeolite but also homogeneously throughout the whole zeolite. This process involves a significant and rapid breaking and re-formation of bonds; however, the zeolite does not dissolve during this process as solid recovery at any given time of the treatment is approximately 100% and the concentration of soluble Si or Al species in the liquid is negligible. Parametric analysis revealed that excessive NaOH leads to the partial transformation of zeolite into an amorphous mesoporous solid, while insufficient quantity of base and/or treatment time can lead to an incomplete mesostructuring of the zeolite, which highlights the importance of judiciously selecting the treatment conditions for every given zeolite. N.L. acknowledges funding from the University of Alicante, through the “Programa de retención y captación de talento” (ref. UATALENTO17-05). J.D.R. acknowledges funding from the Welch Foundation (Award E-1794).

Two magnetically separable Fe3O4/SiO2 (aerogel and MSU-X) composites with very low Fe3O4 content (

The preparation of nanosized zeolites is critical for applications where mass‐transport limitations within microporous networks hinder their performance. Often the ability to generate ultrasmall zeolite crystals is dependent upon the use of expensive organics with limited commercial relevance. Herein, we report the generation of zeolite L crystals with uniform sizes less than 30 nm using a facile, organic‐free method. Time‐resolved analysis of precursor assembly and evolution during nonclassical crystallization highlights key differences among silicon sources. Our findings reveal that a homogenous dispersion of potassium ions throughout silicate precursors leads to the formation of a metastable nonporous phase, which undergoes an intercrystalline transformation to zeolite L. The generation of highly interdispersed alkali‐silicate precursors is seemingly critical to enhancing the rate of nucleation and facilitating the formation of ultrasmall crystal. J.D.R. acknowledges support primarily from the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0014468. Additional support was provided by the Welch Foundation (Award E-1794). N.L. acknowledges support from the University of Alicante under the project GRE15-07.

Mesoporosity can be conveniently introduced into zeolites by treating them in basic surfactant solutions. The apparent activation energy involved in the formation of mesopores in USY by surfactant‐templating was determined using a combination of in situ synchrotron X‐ray diffraction and ex situ gas adsorption. Additionally, techniques such as pH measurement and thermogravimetry/differential thermal analysis were employed to determine OH− evolution and cetyltrimethylammonium ion (CTA+) uptake during the development of mesoporosity, thereby providing information about the different steps involved. The combination of both in situ and ex situ techniques has allowed determination of the apparent activation energies of the different processes involved in the mesostructuring of USY zeolites for the first time. Apparent activation energies are of the same order of magnitude (30–65 kJ mol−1) as those involved in the crystallization of zeolites. Hence, important mechanistic insight into the surfactant‐templating method was obtained. This work was supported by the Spanish MINECO (PCIN-2013-164) and the EC through the ERA-NET CAPITA(AEI/FEDER, project WAVES, EP7-NMP-266543) and the ALBA Synchrotron (refs. 2016021622 and 2016021729). E.S. thanks the Spanish MINECO and AEI/FEDER, UE (CTQ2015-74494-JIN). E.S. and N.L. acknowledge the University of Alicante support (UATALENTO16-03 and UATALENTO17-05, respectively).

A series of low‐temperature, visible‐light‐activated black organotitanias were synthesised through a sol–gel strategy that allowed the in situ incorporation of p‐phenylenediamine (PPD) into the framework of anatase nanoparticles. The effect of the synthetic conditions on the crystalline structure and photocatalytic activity of these materials was assessed by several characterisation techniques, which revealed a small crystalline domain size (4.6–5.5 nm), effective incorporation of PPD inside the nanoparticles, and a significant reduction in the band gap of these materials (from 3.2 to 2.7–2.9 eV). A systematic study of the synthetic parameters also allowed a significant reduction of the solvent used for the preparation of these black organotitanias (20‐fold), as well as the crystallisation time, without compromising the structural properties and photocatalytic activity of these materials. The organotitanias with the highest PPD content and high crystallinity result in the best performing materials in the photocatalytic degradation of rhodamine 6G under both UV‐ and visible‐light irradiation. This study was supported by the Spanish MINECO and AEI/FEDER (ref. CTQ2015-74494-JIN). E.S. and N.L. also thank the University of Alicante (refs. UATALENTO16-03 and UATALENTO17-05, respectively). J.J. acknowledges a fellowship from the University of Alicante. N.L. thanks the Generalitat Valenciana for funding (ref. GV/2016/90).

Pd nanoparticles were easily immobilized onto titanate nanotubes by a straightforward procedure. The material (0.50 wt % Pd) was used as catalyst in the continuous-flow, liquid-phase hydrogenation reaction of unsaturated C−C bonds and it showed excellent performance and durability under very mild conditions (room temperature, 1–2 bar H2, residence time 13–36 s). In particular, very high productivity was obtained in the synthesis of the perfumery component cis-3-hexen-1-ol (40.6 mol gPd−1 h−1) without additives or metal contamination, with clear benefits in terms of process economy and environmental impact compared with conventional catalysts. The catalyst performance is discussed in the light of comparable systems. Thanks are due to the EC Marie-Curie Initial Training Network nano-HOST for funding (Grant Agreement PITN-215193) and to Centro Microscopie Elettroniche—Area di Ricerca CNR, Firenze, for technical support.

Incorporation of various Pd(II) complexes into the framework of mesoporous organosilica materials has been achieved by co-condensation, using a facile solvent-free one-pot method. The synthesis of Pd(II) complexes using ligands with triethoxysilyl terminal groups allowed for their homogeneous in situ incorporation into the organosiliceous structure. Organic/inorganic precursor bis(triethoxysilyl)ethane was used both, as silica source and as solvent for the synthesis of the complexes, avoiding the use of any other organic co-solvent and making the synthesis more environmentally friendly. The mild synthetic conditions used such as neutral pH, room temperature and ethanol extraction of the surfactant, allowed for a cleaner route for the preparation of hybrid organic/inorganic mesoporous materials with Pd(II) complexes covalently bounded to the support. The chemical integrity of the metal complexes after the synthesis of the hybrid material, [trans-PdCl2L2] (L = 4-C5H4N-(CH2)2Si(OEt3) and PPh2(CH2)2Si(OEt)3), was confirmed by several spectroscopic techniques. A systematic study of the role of the different parameters involved in the synthesis of these materials and their relation with the final morphology of the catalysts is herein described.

Interconnected silica spheres (ISS) with hexagonally ordered mesopores have been synthesized with only a quarter of the total amount of surfactant used in the most surfactant-effective synthesis reported to date, i.e. a surfactant/silica molar ratio of 0.03. A MCM-41-type silica material with spherical core/shell morphology and an average particle size of ca. 250 nm was produced using a simple one-pot hydrothermal step. The shape of the spheres as well as their properties was found to be dependent on the synthesis parameters such as the ammonia and surfactant concentration, being the optimum ammonia/surfactant molar ratio ca. 2000. The samples prepared under these conditions have specific areas of 400–450 m2 g−1 and mesopore volumes up to 0.5 cm3 g−1.

Incorporation of various Pd(ii) complexes into the framework of MSU-X mesoporous silica has been achieved by co-condensation using a facile solvent-free one-pot synthesis. The use of ligands with triethoxysilyl terminal groups permitted the synthesis of three different metallosilanes precursors (metal complexes with ligands containing trialkoxysilane terminal groups), which allow for the homogeneous in situ incorporation of metal complexes covalently bonded to the porous support. Inorganic precursor tetraethylorthosilicate was used both as silica source and as solvent for the synthesis of the complexes, avoiding the use of other organic co-solvents, making the synthesis environmentally benign. The gentle synthesis conditions used such as neutral pH, room temperature and mild ethanol extraction of the surfactant, allowed a cleaner route for the immobilization of homogeneous Pd(ii) catalysts in mesoporous silica, while protecting the structural and chemical integrity of the metal complexes. For comparison purposes, monomer complexes [trans-PdCl 2L 2] (L = NH 2(CH 2) 3Si(OEt) 3, 4-C 5H 4N-(CH 2) 2Si(OEt 3), PPh 2(CH 2) 2Si(OEt) 3) were synthesized using the same aerobic reaction conditions to those use for the co-condensation processes and fully characterized before their incorporation in the mesoporous silica. The catalytic performance of these materials was tested for the Suzuki-Miyaura reaction under solvent-free conditions. Efficient mixing of all the components was accomplished by applying either magnetic stirring or ball milling. The good yields obtained, even at room temperature, confirmed the catalytic activity of the metal complexes once incorporated into the mesoporous silica framework. The possibility to work under solvent-free conditions even with solid starting reactants, is a significant step forward in the Suzuki-Miyaura coupling reaction because its benefits in terms of cost and impact of the environment. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2011.

Bimodal macro-mesoporous silica networks have been prepared in a simple one-pot synthesis using an inexpensive tetramine surfactant and tetraethoxysilane as a silica precursor. These novel materials show high pore volumes and templated mesopores (average pore size 3.0 nm) embedded in 20 nm thick walls forming interparticle large meso/macropores. The judicious control of the pH during the silica formation allows for the precise control of the interparticle condensation, likely due to the change in the interaction between the tetramine surfactant and the silica precursors. Finally, a highly porous carbon replica with bimodal porosity was prepared by using the bimodal silica as a hard sacrificial template. The microstructure of the silica template was accurately transferred to the carbon material obtaining high surface areas (up to 1300 m{sup 2} g{sup -1}) and total pore volumes >=2 cm{sup 3} g{sup -1}. - Graphical abstract: Hierarchical bimodal porous silica and its carbon replica prepared by nanocasting.

Monodisperse Pd nanoparticles were prepared by controlled reduction in organic phase and subsequent transfer to aqueous phase. A systematic study was carried out to finely tune nanoparticle size and optimize particle size distribution. The use of 4-dimethylaminopyridine as a transfer agent allowed for the easy and quantitative extraction of the Pd to the aqueous phase. The quaternary amine-functionalized metal nanoparticles were then used as metallic micelle replicas to grow silica around them. This novel and facile metal incorporation method provided an excellent dispersion and homogeneity of Pd nanoparticles on silica supports. In addition, cationic surfactants, such as cetyltrimethylammonium bromide, can be used to produce mesoporosity in these nanoparticles-containing silicas. As an alternative, the metal nanoparticles were functionalized with alkoxysilanes by covalent binding using mercaptopropyltriethoxysilane and then co-polymerized with tetraethoxysilane via basic-catalyzed hydrolysis in the presence of cationic surfactants.

Alternative energy technologies are greatly hindered by significant limitations in materials science. From low activity to poor stability, and from mineral scarcity to high cost, the current materials are not able to cope with the significant challenges of clean energy technologies. However, recent advances in the preparation of nanomaterials, porous solids, and nanostructured solids are providing hope in the race for a better, cleaner energy production. The present contribution critically reviews the development and role of mesoporosity in a wide range of technologies, as this provides for critical improvements in accessibility, the dispersion of the active phase and a higher surface area. Relevant examples of the development of mesoporosity by a wide range of techniques are provided, including the preparation of hierarchical structures with pore systems in different scale ranges. Mesoporosity plays a significant role in catalysis, especially in the most challenging processes where bulky molecules, like those obtained from biomass or highly unreactive species, such as CO2 should be transformed into most valuable products. Furthermore, mesoporous materials also play a significant role as electrodes in fuel and solar cells and in thermoelectric devices, technologies which are benefiting from improved accessibility and a better dispersion of materials with controlled porosity.

Colloidal gold nanoparticles were synthesized by different procedures affording suspensions with two different mean sizes (2 and 5 nm). Au catalysts were prepared by sol immobilization onto several silica frameworks with different 2D and 3D mesoporosities. The catalysts were tested in styrene oxidation reactions showing excellent efficiency and selectivity. The effect of nanoparticle size and mesoporous framework on the physical and catalytic properties of the final materials was studied. The most selective catalyst was prepared from the 5 nm Au nanoparticles and the more interconnected silica framework (3D mesoporosity). The authors are grateful for the funding under project CTQ2011-28954-C02-01(02) from the SpanishMICINN. NL acknowledges the financial support from the FPI Program (ref. BES-2006-13056).

Alternative energy technologies are greatly hindered by significant limitations in materials science. From low activity to poor stability, and from mineral scarcity to high cost, the current materials are not able to cope with the significant challenges of clean energy technologies. However, recent advances in the preparation of nanomaterials, porous solids, and nanostructured solids are providing hope in the race for a better, cleaner energy production. The present contribution critically reviews the development and role of mesoporosity in a wide range of technologies, as this provides for critical improvements in accessibility, the dispersion of the active phase and a higher surface area. Relevant examples of the development of mesoporosity by a wide range of techniques are provided, including the preparation of hierarchical structures with pore systems in different scale ranges. Mesoporosity plays a significant role in catalysis, especially in the most challenging processes where bulky molecules, like those obtained from biomass or highly unreactive species, such as CO2 should be transformed into most valuable products. Furthermore, mesoporous materials also play a significant role as electrodes in fuel and solar cells and in thermoelectric devices, technologies which are benefiting from improved accessibility and a better dispersion of materials with controlled porosity. The authors wish to thank the Spanish MINECO (Project CTQ2011-28954-C02-01) for financial support. E.S. acknowledges financial support from UA (Project GRE12-39).

The development of synthetic routes for the tailoring of efficient silica-based heterogeneous catalysts functionalized with coordination complexes or metallic nanoparticles has become a important goal in chemistry. Most of these techniques have been based on postsynthetic treatments of preformed silicas. Nevertheless, there is an emerging approach, so-called sol–gel coordination chemistry, based on co-condensation during the sol–gel preparation of the hybrid material of the corresponding complex or nanoparticle modified with terminal trialkoxysilane groups with a silica source (such as tetraethoxysilane) and in the presence of an adequate surfactant. This method leads to the production of new mesoporous metal complex-silica materials, with the metallic functionality incorporated homogeneously into the structure of the hybrid material, improving the stability of the coordination complex (which is protected by the silica network) and reducing the leaching of the active phase. This technique also offers the actual possibility of functionalizing silica or other metal oxides for a wider range of applications, such as photonics, sensing, and biochemical functions.

Metal-complex ionosilicas with cationic complexes into the mesoporous silica framework were prepared using anionic surfactants. The electrostatic interaction between the anionic surfactant and the cationic metal complexes incorporated in the silica framework allows for the fine tuning of the mesoporous structure. The gentle procedure of synthesis developed and mild ion-exchange extraction of the surfactant, allowed a cleaner route for the immobilization of homogeneous cationic catalysts in mesoporous silica, while protecting the structural and chemical integrity of the metal complexes. The authors are grateful for funding under project CTQ2011-28954-C02-01(02) from the Spanish MICINN. E.S. is grateful for financial support under the JdC Program (Ref. JCI 2008-2165) and from GV (Ref.BEST2011/223). NL acknowledges financial support from the FPI Program (Ref. BES-2006-13056).

Well-dispersed Pd nanoparticles have been synthesized inside the mesoporosity of a silica monolith featuring hierarchical porosity of homogeneous interconnected macropores (4 microns) and mesopores (11 nm). These monoliths have been implemented as microreactors for selective hydrogenation reactions. Conversion and selectivity can be tuned by adjusting the flow rates of hydrogen and substrates. In the selective hydrogenation of cyclooctadiene, a conversion of 95% and a selectivity of 90% in the monohydrogenated product, constant over a period of 70 h, have been reached. These figures correspond to a productivity of 4.2 mmol s−1 g−1MonoSil (or 0.32 mol s−1 g−1Pd). In the stereoselective hydrogenation of 3-hexyn-1-ol a constant conversion of 85% was observed, with however moderate selectivity into the cis isomer, over a test period of 7 h. These results open the route to the synthesis of important chemicals and intermediates via safe and green processes. The research leading to these results has received funding from the European Community’s Seventh Framework Program through the Marie-Curie Initial Training Network NANO-HOST (Grant Agreement ITN 215193-2).

The development of synthetic routes for the tailoring of efficient silica-based heterogeneous catalysts functionalized with coordination complexes or metallic nanoparticles has become a important goal in chemistry. Most of these techniques have been based on postsynthetic treatments of preformed silicas. Nevertheless, there is an emerging approach, so-called sol–gel coordination chemistry, based on co-condensation during the sol–gel preparation of the hybrid material of the corresponding complex or nanoparticle modified with terminal trialkoxysilane groups with a silica source (such as tetraethoxysilane) and in the presence of an adequate surfactant. This method leads to the production of new mesoporous metal complex-silica materials, with the metallic functionality incorporated homogeneously into the structure of the hybrid material, improving the stability of the coordination complex (which is protected by the silica network) and reducing the leaching of the active phase. This technique also offers the actual possibility of functionalizing silica or other metal oxides for a wider range of applications, such as photonics, sensing, and biochemical functions. We thank the Spanish MINECO (Projects CTQ2011-28954-C02-01 and CTQ2008-06669-C02-02/BQU) and the CAR (COLABORA project 2009/05) for financial support. E.S. acknowledges financial support from JCI 2008-2165 and BEST2011/223 projects.

Heterogeneous catalysts enabling multiple reaction sequences in one pot have a great potential for large-scale production processes in terms of productivity, cost-effectiveness, and low environmental impact. This paper reviews the most representative examples and the recent achievements in the field of solid bifunctional metal/acid-site catalysts and their application to the production of fine chemicals through selective, cooperative, or sequential processes in single reactor units. The literature that appeared from January 2009 to January 2012 is covered.

Pd nanoparticles are immobilized by a green procedure onto unconventional dual porosity titania monoliths. The material is used in catalytic continuous-flow hydrogenation reactions showing excellent efficiency, selectivity, and durability.

Heterogeneous catalysts enabling multiple reaction sequences in one pot have a great potential for large-scale production processes in terms of productivity, cost-effectiveness, and low environmental impact. This paper reviews the most representative examples and the recent achievements in the field of solid bifunctional metal/acid-site catalysts and their application to the production of fine chemicals through selective, cooperative, or sequential processes in single reactor units. The literature that appeared from January 2009 to January 2012 is covered.

Mesoporous silica, which shows well-defined pore systems, tunable pore diameters (2–30 nm), narrow pore size distributions and high surface areas (>600 m2 g−1), is frequently modified using different methodologies (including in situ and post-synthetic strategies) to introduce various chemical functionalities useful in applications like catalysis, separation, drug delivery, and sensing. This contribution aims to provide a critical overview of the various strategies to incorporate chemical functionalities in mesoporous silica highlighting the advantages of the in situ methods based on the bottom-up construction of mesoporous silica containing various chemical functionalities in its structure.

Mesoporous silica, which shows well-defined pore systems, tunable pore diameters (2-30 nm), narrow pore size distributions and high surface areas (600 m(2) g(-1)), is frequently modified using different methodologies (including in situ and post-synthetic strategies) to introduce various chemical functionalities useful in applications like catalysis, separation, drug delivery, and sensing. This contribution aims to provide a critical overview of the various strategies to incorporate chemical functionalities in mesoporous silica highlighting the advantages of the in situ methods based on the bottom-up construction of mesoporous silica containing various chemical functionalities in its structure.

Water soluble, monodispersed Pd nanoparticles with a narrow particle size distribution have been successfully synthesized by controlled reduction of [PdCl4]2−. The resulting aqueous colloids are stable over extended periods of time and can be prepared at high nanoparticle loading (20 g/L of Pd) with no agglomeration. The size of the nanoparticles can be reduced from the nanometer (ca. 3.5 nm) to the sub-nanometer size range (ca. 0.9 nm). Detailed magnetic characterization indicated that the larger, 3.5 nm nanoparticles show ferromagnetic properties at room temperature, while the sub-nanometric ones lose this magnetic behavior.