Nitric oxide production from nitrite by a series of zeolites produced via the ADOR route

We would like to thank the Engineering and Physical Sciences Research Council (EPSRC), University of St Andrews, and CRITICAT Centre for Doctoral Training for financial support [Ph.D. studentship to SR; Grant code: EP/L016419/1]. We also thank the EPSRC for funding part of this work through grant EP/K025112/1. R.E.M. would like to acknowledge OP VVV "Excellent Research Teams", project No. CZ.02.1.01/0.0/0.0/15_003/0000417 – CUCAM.The nitric oxide (NO) production for a series of aluminosilicate zeolites, prepared using the ADOR method, was investigated. Al-UTL and Al-IPC-2,-4 and −6 were prepared and characterised to determine their elemental composition. Positive trends were found to exist between zeolite pore size and the rate and total amount of NO produced. A trend between the number of acid sites and the initial rate of NO produced by the zeolite was also discovered.PostprintPeer reviewe

Assessment of Variable-cycle Engines for Mach 2.7 Supersonic Transports

Three proposed SCAR propulsion systems in terms of aircraft range for a fixed payload and take-off gross weight with a design cruise Mach number 2.7 are evaluated. The effects of various noise and operational restraints are determined and sensitivities to some of the more important performance variables are presented for the most probable design noise and operational restraint case. Critical areas requiring new or improved technology for each cycle are delineated

New avenues for mechanochemistry in zeolite science

D. N. R. would like to thank the EPSRC for funding (grant no. EP/N509759/1). R. E. M. is funded by an ERC Advanced Grant (787073 ADOR) and acknowledges the Charles University Centre of Advanced Materials (CUCAM) (OP VVV “Excellent Research Teams”, project number CZ.02.1.01/0.0/0.0/15_003/0000417 – CUCAM).Zeolites are a class of microporous materials with tremendous value for large scale industrial applications such as catalysis, ion exchange, or gas separation. In addition to naturally ocurring variants, zeolites are made synthetically using hydrothermal synthesis, requiring temperatures beyond 100 °C and long reaction times up to weeks. Furthermore, specific applications may require more sophisticated synthesis conditions, expensive reagents, or post-synthetic modifications. Some of these issues can be tackled by using the reemerged technique of mechanochemistry. In 2014, Majano et al. reviewed the space and outlined several possibilities for the usage of mechanical forces in zeolite chemistry. Since then the field has seen many more publications employing mechanochemical methodology to further and improve the synthesis and properties of zeolite materials. The usage ranges from the activation of raw materials, rendering the synthesis of the widely used catalysts much more economical in terms of duration, atom efficiency, and production of waste, to post-synthetic modification of the materials leading to improved properties for target aplications. We present a short review of the advances that have been reported recently, highlight promising work and important studies, and give a perspective of potential future endeavours.Publisher PDFPeer reviewe

Selective oxidation of bulky organic sulphides over layered titanosilicate catalysts

The authors acknowledge the Czech Science Foundation (P106/12/G015) for the financial support.Selective oxidation of sulphides is a straightforward method of preparation of organic sulphoxides and sulphones, which are important chemical intermediates and building blocks of pharmaceuticals and agrochemicals. Oxidation of methylphenyl sulphide (MPS), diphenyl sulphide (Ph2S), and dibenzothiophene (DBTH) over lamellar titanosilicate catalysts with the MFI and UTL-derived topology was investigated with hydrogen peroxide as the oxidant. Lamellar titanosilicates combine the advantages of crystalline zeolites and mesoporous molecular sieves due to accessible active sites located on the external surface of their layers. The selectivity of the MPS oxidation to methylphenyl sulphoxide is driven by the diffusion restrictions in the catalyst. A methylphenyl sulphoxide selectivity of 95% at 40% conversion was achieved using the Ti-IPC-1-PI catalyst together with an outstanding TONtot = 1418 after 30 min. The selectivity can be adjusted also by dosing of the oxidant to keep its concentration low during the reaction. The silica-titania pillared TS-1-PITi catalyst showed the highest potential of the tested catalysts in oxidative desulphuration, easily oxidising the DBTH to dibenzothiothene sulphone.PostprintPeer reviewe

Pair distribution function analysis of the reassembly step of the assembly-disassembly-organisation-reassembly (ADOR) process

The authors S. E. R and R. E. M. would like to thank the European Research Council for funding opportunities under the Advanced Grant 787073. We acknowledge Diamond Light Source for time on I15-1 under proposal CY26990.An in situ pair distribution function study assessing the reassembly of three IM-12 (UTL) intermediate materials to the corresponding fully connected materials. A greater level of atomic change is observed at higher temperatures for the reassembly of the fully disconnected intermediate, IPC-1P, compared to the two partially connected intermediates of IPC-2P and IPC-6P.Publisher PDFPeer reviewe

Selective oxidation of bulky organic sulphides over layered titanosilicate catalysts

The authors acknowledge the Czech Science Foundation (P106/12/G015) for the financial support.Selective oxidation of sulphides is a straightforward method of preparation of organic sulphoxides and sulphones, which are important chemical intermediates and building blocks of pharmaceuticals and agrochemicals. Oxidation of methylphenyl sulphide (MPS), diphenyl sulphide (Ph2S), and dibenzothiophene (DBTH) over lamellar titanosilicate catalysts with the MFI and UTL-derived topology was investigated with hydrogen peroxide as the oxidant. Lamellar titanosilicates combine the advantages of crystalline zeolites and mesoporous molecular sieves due to accessible active sites located on the external surface of their layers. The selectivity of the MPS oxidation to methylphenyl sulphoxide is driven by the diffusion restrictions in the catalyst. A methylphenyl sulphoxide selectivity of 95% at 40% conversion was achieved using the Ti-IPC-1-PI catalyst together with an outstanding TONtot = 1418 after 30 min. The selectivity can be adjusted also by dosing of the oxidant to keep its concentration low during the reaction. The silica-titania pillared TS-1-PITi catalyst showed the highest potential of the tested catalysts in oxidative desulphuration, easily oxidising the DBTH to dibenzothiothene sulphone.PostprintPeer reviewe

Controllable surfactant-directed zeolitic-imidazolate-8 growth on swollen 2D zeolites

The authors would like to thank the European Research Council for funding opportunities under Advanced Grant No. 787073. The EPSRC Light Element Analysis Facility under Grant No. EP/T019298/1 and the EPSRC Strategic Equipment Resource under Grant No. EP/R023751/1 are gratefully acknowledged.To meet society’s need for more and more specialized materials, this work focuses on the preparation of porous metal–organic framework (MOF)–zeolite hybrid materials based on two 2D zeolites, namely, IPC-1P (Institute of Physical Chemistry - 1 Precursor) and the metal–organic framework ZIF-8 (Zeolitic Imidazolate Framework-8). Using the previously well-established assembly–disassembly–organization–reassembly method, the zeolite was (i) synthesized, (ii) hydrolyzed to a layered zeolite, (iii) the interlayer distance was increased using the swelling agent cetyltrimethylammonium chloride, and (iv) nanocrystals of ZIF-8 were grown stepwise on the zeolite surface but predominantly at the edges of the crystallites where the openings to the interlayer region are located. This selective MOF growth and attachment was facilitated by a combination of intercalation of the metal ions and the swelling agent between the zeolite layers. The influence of the solvent and the number of additional steps on the ZIF-8 growth on the zeolite was systematically investigated, and the synthesis protocol was successfully adapted to a further two-dimensional silicate RUB-18 (Ruhr-Universität Bochum - 18). This paves the way toward the controlled preparation of more MOF–zeolite hybrid materials, which might provide interesting properties for future applications.Publisher PDFPeer reviewe

Low temperature synthesis study of metal-organic framework CPO-27 : investigating metal, solvent and base effects down to -78 °C

We thank the EPSRC (EP/K005499/1) (EP/K503162/1) for their financial support of this project and the EPSRC Capital for Great Technologies (EP/L017008/1).CPO-27-M (M = Co, Mg, Ni, Zn) metal-organic frameworks have been successfully synthesized at temperatures down to -78 °C in a range of solvent systems and their crystallinity and morphology analyzed by powder X-ray diffraction and scanning electron microscopy. CPO-27-Mg and -Zn could be synthesized at lower temperatures using MeOH-NaOH as the solvent with CPO-27-Zn showing the most crystalline material at -78 °C. CPO-27-Zn afforded the most crystalline samples of all studies in MeOH-TEA. However, in MeOH a non-porous monomeric [Zn(H2dhtp)(H2O)2] complex was formed when no base was present. In THF with base (NaOH, TEA) the reaction produced crystalline MOFs in a controlled and stable manner at low temperatures, whilst the reagents were insoluble in THF at low temperature when no base was present. SEM was used to analyze the morphologies of the products.PostprintPeer reviewe

Exploring cation distribution in ion-exchanged Al,Ga-containing metal-organic frameworks using 17O NMR spectroscopy

The authors would like to thank the ERC (Advanced Grant 787073 ADOR) for support. The UK High-Field Solid-State NMR Facility used in this research was funded by EPSRC and BBSRC (EP/T015063/1), in addition to (for results at 850 MHz) he University of Warwick including via part funding through Birmingham Science City Advanced Materials Projects 1 and 2 supported by Advantage West Midlands (AWM) and the European Regional Development Fund (ERDF), and for the 1 GHz instrument, (EP/R029946/1). Collaborative assistance from the Facility Manager Team (Dr Trent Franks, University of Warwick) is acknowledged. The Jeol JSM-IT200 SEM used in this research was supported by the EPSRC Light Element Analysis Facility Grant (EP/T019298/1) and the EPSRC Strategic Equipment Resource Grant (EP/R023751/1). Collaborative assistance from Dr David Miller (University of St Andrews) is acknowledged.A mixed-metal metal–organic framework, (Al,Ga)-MIL-53, synthesised by post-synthetic ion exchange has been investigated using solid-state nuclear magnetic resonance (NMR) spectroscopy, microscopy and energy dispersive X-ray (EDX) spectroscopy. 17O enrichment during the ion-exchange process enables site specific information on the metal distribution to be obtained. Within this work two ion-exchange processes have been explored. In the first approach (exchange of metals in the framework with dissolved metal salts), 17O NMR spectroscopy reveals the formation of crystallites with a core–shell structure, where the cation exchange takes place on the surface of these materials forming a shell with a roughly equal ratio of Al3+ and Ga3+. For the second approach (exchange of metals between two frameworks), no core–shell structure is observed, and instead crystallites containing a majority of Al3+ are obtained with lower levels of Ga3+. Noticeably, these particles show little variation in the metal cation distribution between crystallites, a result not previously observed for bulk (Al,Ga)-MIL-53 materials. In all cases where ion exchange has taken place NMR spectroscopy reveals a slight preference for clustering of like cations.Publisher PDFPeer reviewe

Understanding the synthesis and reactivity of ADORable zeolites using NMR spectroscopy

The authors would like to thank the ERC (EU FP7 Consolidator Grant 614290 EXONMR and Advanced Grant 787073 ADOR) and EPSRC (EP/N509759/1) for a studentship for CMR. The research data (and/or materials) supporting this publication can be accessed at https://doi.org/10.17630/d82e58e4-b4a0-40b3-8156-5cbf80eeea72Zeolites remain one of the most important class of industrial catalyst used today, and with the urgent drive for transition from petrochemical to renewable feedstocks there is a renewed interest in developing new types of zeolite. Recent synthetic advances in the field have included the development of the Assembly-Disassembly-Organisation-Reassembly (ADOR) method. In this short review we will discuss how solid-state NMR experiments can be used to probe the mechanism of the process by characterising the structure of the intermediates and products, show how 17O NMR spectroscopy can be used to probe the reactivity of ADORable zeolites and explain how this in turn can lead to fundamental questions of how zeolites behave in the presence of liquid water.Publisher PDFPeer reviewe