Designed synthesis of STA-30 : a small pore zeolite catalyst with topology type SWY

R.G.C. thanks the University of St Andrews and Johnson Matthey for funding. P.A.W. thanks the EPSRC (Designed Synthesis of Zeolites: EP/S016201/1) and the Royal Society (Industry Fellowship INF\R2\192052) for support. A.M. acknowledges the Spanish Ministry of Science and Innovation through the Ramon y Cajal programme (RYC2018-024561-I), the Regional government of Aragon (DGA E13_20R), and to the National Natural Science Foundation of China (NFSC-21850410448; NSFC-21835002).Small-pore aluminosilicate zeolites are attractive targets for synthesis because of their activity as catalysts in important reactions, including ammonia-mediated selective catalytic reduction (SCR) of NOx in auto-exhaust emissions. Such a zeolite with SWY framework type, previously observed as a silicoaluminophosphate, has been prepared with high crystallinity via designed syntheses employing organic 1,8-(1,4-diazabicyclo[2.2.2]octane)octyl (diDABCO-C8) and K+ cations as templates. STA-30 (St Andrews microporous material 30) is an ABC-6 structure in the erionite-offretite family of zeolites that exhibits the 12-layer stacking sequence AABAABAACAAC. The framework, which can be prepared with a controllable Si/Al ratio, possesses columns of alternating d6r units and can cages, of which the latter are oriented to give an inter-column pore space comprising gme cages and swy cages connected via 8Rs. DiDABCO-C8 cations fill the swy cages of as-prepared STA-30, while K+ cations display high occupancy in the can cages. Removal of the template by calcination, followed by ammonium ion exchange of K+ cations residing outside the can cages and subsequent deammoniation, gives a highly crystalline zeolite (K3H6Al9Si72O144, P63/mmc, a = 12.9922(9) Å, c = 29.9624(12) Å) with solid acidity shown by solid-state 1H MAS NMR. Upon hydration, a portion of the Al adopts octahedral geometry, as demonstrated by two sharp resonances at −2.0 and −3.1 ppm in the 27Al MAS NMR. These octahedral species can be converted back to tetrahedral Al by ammonium exchange and are interpreted as distinct hydrated framework Al sites. The activated K,H-STA-30 is a small-pore solid acid with a three-dimensionally connected micropore volume of 0.31 cm3 g–1. In the copper-loaded form, it is an active catalyst for the SCR of NO by ammonia.PostprintPostprintPeer reviewe

Synthetic control of defect structure and hierarchical extra-large/small-pore microporosity in aluminosilicate zeolite SWY

R.G.C. thanks the University of St. Andrews and Johnson Matthey for funding. P.A.W. thanks the Royal Society (Industrial Fellowship INF\R2\192052) for support. R.G.C. acknowledges the support of the EPSRC Light Element Analysis Facility grant EP/T019298/1 and the EPSRC Strategic Equipment Resource grant EP/R023751/1 for the use of the Jeol JSM-IT800 electron microscope at the University of St Andrews. A.M. acknowledges the Spanish Ministry of Science (RYC2018-024561-I) and the Gobierno of Aragon (Nanomidas group, code E13_23R).The SWY-type aluminosilicate zeolite, STA-30, has been synthesized via different routes to understand its defect chemistry and solid acidity. The synthetic parameters varied were the gel aging, the Al source, and the organic structure directing agent. All syntheses give crystalline materials with similar Si/Al ratios (6–7) that are stable in the activated K,H-form and closely similar by powder X-ray diffraction. However, they exhibit major differences in the crystal morphology and in their intracrystalline porosity and silanol concentrations. The diDABCO-C82+ (1,1′-(octane-1,8-diyl)bis(1,4-diazabicyclo[2.2.2]octan)-1-ium)-templated STA-30 samples (but not those templated by bisquinuclidinium octane, diQuin-C82+) possess hierarchical microporosity, consisting of noncrystallographic extra-large micropores (13 Å) that connect with the characteristic swy and gme cages of the SWY structure. This results in pore volumes up to 30% greater than those measured in activated diQuin-C8_STA-30 as well as higher concentrations of silanols and fewer Brønsted acid sites (BASs). The hierarchical porosity is demonstrated by isopentane adsorption and the FTIR of adsorbed pyridine, which shows that up to 77% of the BASs are accessible (remarkable for a zeolite that has a small-pore crystal structure). A structural model of single can/d6r column vacancies is proposed for the extra-large micropores, which is revealed unambiguously by high-resolution scanning transmission electron microscopy. STA-30 can therefore be prepared as a hierarchically porous zeolite via direct synthesis. The additional noncrystallographic porosity and, subsequently, the amount of SiOHs in the zeolites can be enhanced or strongly reduced by the choice of crystallization conditions.Publisher PDFPeer reviewe

Factors Associated With Response and Resistance to Cognitive Remediation in Schizophrenia: A Critical Review

Cognitive impairment is a central feature of schizophrenia and has shown to play a crucial role in the psychosocial function of the disorder. Over the past few years, several cognitive remediation (CR) interventions have been developed for schizophrenia, whose effectiveness has also been widely demonstrated by systematic reviews and meta-analysis studies. Despite these evidences, many questions remain open. In particular, the identification of CR response predictors in patients with schizophrenia is still a topic with equivocal findings and only a few studies have looked for the relationship between CR response or resistance and the biological, socio-demographic, clinical and cognitive features in schizophrenia. The current knowledge on positive or negative response predictors to CR treatment in schizophrenia include: age, duration of illness, premorbid adjustment, baseline cognitive performance, intrinsic motivation, hostility, disorganized symptoms, neurobiological reserve, genetic polymorphisms, the amounts of antipsychotics, the type of CR, etc. The aim of this review is to identify neurobiological, psychopathological, cognitive, and functional predictors of CR response or resistance in schizophrenia, taking into account both cognitive and functional outcome measures. The information obtained could be very useful in planning integrated and personalized interventions, also with a better use of the available resources

Cation control of cooperative CO2 adsorption in Li-containing mixed cation forms of the flexible zeolite merlinoite

The authors thank the EPSRC for funding (Cation-Controlled Gating for Selective Gas Adsorption over Adaptable Zeolites: EP/N032942/1, V.M.G., P.A.W. and an NPIF Ph.D. scholarship for E.L.B.: EP/R512199/1). We acknowledge Diamond Light Source for time on Beamline I11 under Proposal CY22322-1. Experiments at the ISIS Neutron and Muon Source were supported by a beamtime allocation RB2090052-1 from the Science and Technology Facilities Council. The raw data accompanying this publication are directly available at https://doi.org/10.17630/cac904b4-3c07-4159-913f80ff53b13bb7 [reference 59] and, for the neutron powder diffraction data, https://doi.org/10.5286/ISIS.E.RB2090052-1The lithium-exchanged form of a merlinoite zeolite (MER) with Si/Al = 4.2 (unit cell composition Li6.2Al6.2Si25.8O64) possesses a strongly contracted framework when dehydrated (the unit cell volume decreases by 12.9% from the hydrated ‘wide-pore’ form to the dehydrated ‘narrow-pore’ form). It shows cooperative adsorption behaviour for CO2, leading to two-step isotherms with the second step at elevated pressure (>2.5 bar at 298 K). Partially exchanging Na and K cations to give single phase Li,Na- and Li,K-MER materials reduces the pressure of this second adsorption step because the transition from narrow- to wide-pore forms upon CO2 adsorption occurs at lower partial pressures compared to that in Li-MER: partial exchange with Cs does not reduce the pressure of this transition. Exsolution effects are also seen at K cation contents >2.2 per unit cell. The phase transitions proceed via intermediate structures, by complex phase behaviour rarely seen for zeolitic materials. The strongly distorted narrow-pore structures adopted upon dehydration give one dimensional channel structures in which the percolation of CO2 through the material requires cation migration from their locations in ste sites. This is slow in Li3.4Cs2.8-MER where Cs cations occupy these critical ste cavities in the channels, causing very slow adsorption kinetics. As the partial pressure of CO2 increases, a threshold pressure is reached where cooperative adsorption and Cs cation migration occur and the wide-pore form results, with a three dimensionally connected pore system, leading to a sharp increase in uptake. This is far in excess of the increase of unit cell volume because more of the pore space becomes accessible. Strong hysteretic effects occur upon desorption, leading to CO2 encapsulation. CO2 remaining within the material after repeated adsorption/desorption cycles without heated activation improves sorption kinetics and modifies the stepped isotherms.PostprintPostprintPeer reviewe

Understanding the structure directing action of copper-polyamine complexes in the direct synthesis of Cu-SAPO-34 and Cu-SAPO-18 catalysts for the selective catalytic reduction of NO with NH3

This work has been supported by Johnson Matthey PLC, UK.Cu2+ cations complexed by linear polyamines have been studied as structure-directing agents (SDAs) for the direct synthesis of copper-containing microporous silicoaluminophosphate (SAPO) materials. The complexing ligands diethylenetriamine (DETA), N-(2-hydroxyethyl)ethylenediamine (HEEDA), triethylenetetramine (TETA), N,N′-bis(2-aminoethyl)-1,3-propanediamine (232), 1,2-bis(3-aminopropylamino)ethane (323), tetraethylenepentamine (TEPA) and pentaethylenehexamine (PEHA) have been investigated. For comparison, syntheses have been performed using the analogous nickel-polyamine complexes. Cu2+ and Ni2+ forms of both SAPO-18 and SAPO-34 materials have been prepared. While most polyamine complexes direct crystallisation to SAPO-34, SAPO-18 has been prepared with Cu2+(232), Ni2+(232) and Ni2+(TETA). The coordination geometry of the included metal complexes was studied by UV-visible and EPR spectroscopy and computer simulation. SAPO-18 is favoured by the smaller square planar complexes or octahedral species (with 2 water molecules) of 232 and TETA. Calcination leaves extra-framework Cu2+ and Ni2+ cations within SAPO-18 and SAPO-34 frameworks. In situ synchrotron IR spectroscopy of Ni-SAPO-18 has shown thermal template degradation occurs via nitrile intermediates. Rietveld structural analysis located extra-framework Cu2+ and Ni2+ cations released by calcination. In SAPO-34, Cu2+ and Ni2+ were located in the 8R window of the cha cage. A second site was found for Ni2+ at the centre of the six-membered rings (6Rs) of the double-six-ring (D6R) sub-units. In SAPO-18 both Cu2+ and Ni2+ cations were located only in the 6Rs of the D6R sub-units. Selected copper SAPO-18 and SAPO-34 samples were tested in the selective catalytic reduction of NO with ammonia (NH3-SCR); both showed high activity.PostprintPostprintPeer reviewe

Synthesis and activation for catalysis of Fe-SAPO-34 prepared using iron polyamine complexes as structure directing agents

This work was supported by Johnson Matthey PLC, UK. Solid-state NMR spectra were obtained at the EPSRC UK National Solid-state NMR Service at Durham.The use of transition metal cations complexed by polyamines as structure directing agents (SDAs) for silicoaluminophosphate (SAPO) zeotypes provides a route, via removal of the organic by calcination, to microporous solids with well-distributed, catalytically-active extra-framework cations and avoids the need for post-synthesis aqueous cation exchange. Iron(II) complexed with tetraethylenepentamine (TEPA) is found to be an effective SDA for SAPO- 34, giving as-prepared solids where Fe2+-TEPA complexes reside within the cha cages, as indicated by Mössbauer, optical and X-ray absorption near edge spectroscopies. By contrast, when non-coordinating tetraethylammonium ions are used as the SDAs in Fe-SAPO-34 preparations, iron is included as octahedral Fe3+ within the framework. The complex- containing Fe-SAPO-34(TEPA) materials give a characteristic visible absorption band at 550 nm (and purple colouration) when dried in air that is attributed to oxygen chemisorption. Some other Fe2+ polyamine complexes (diethylenetriamine, triethylenetetramine and pentaethylenehexamine) show similar behaviour. After calcination in flowing oxygen at 550 °C, ‘one-pot’ Fe(TEPA) materials possess Fe3+ cations and a characteristic UV-visible spectrum: they also show appreciable activity in the selective catalytic reduction of NO with NH3.PostprintPostprintPeer reviewe

A retrosynthetic co-templating method for the preparation of silicoaluminophosphate molecular sieves

This work has been supported by Johnson Matthey PLC, UK. Solid-state NMR spectra were obtained at the EPSRC UK National Solid-state NMR Service at Durham.A retrosynthetic method has been developed to design the synthesis of target zeotypes whose frameworks belong to the ABC-6 structural family and which contain gme cages. This permits the preparation of silicoaluminophosphate versions of AFX (SAPO-56), SFW (STA- 18) and GME (STA-19) topology types. The method makes simultaneous use of two organic structure directing agents (SDAs) to promote the formation of structural features such as cages or channels of the target framework. Computational modelling was used to identify SDAs for gme and other cages or channels in the target structures. The trimethylammonium cation was found to be the most favourable SDA for the gme cage while bisdiazabicyclooctane (DABCO) alkane cations and quaternary ammonium oligomers of DABCO with connecting polymethylene chain lengths of 4 to 8 methylene units acted as 1 templates for the additional cages or channels, respectively. The incorporation of each of the co-SDAs in the as-prepared materials was confirmed by chemical analysis, 13C MAS NMR and Rietveld refinement combined with computational modeling. Calcination of the SAPO- 56, STA-18 and some of the STA-19 materials gives microporous, fully tetrahedrally- coordinated framework solids with AFX, SFW and GME topologies: other STA-19 samples convert topotactically to SAPO-5. These results show that SAPOs in the ABC-6 family can be prepared via a targeted co-templating approach.PostprintPostprintPeer reviewe

Site-specific iron substitution in STA-28, a large pore aluminophosphate zeotype prepared using 1,10-phenanthrolines as framework-bound templates

Funding: UK Engineering and Physical Sciences Research Council (Grant Number(s): EP/N50936X/1, EP/S016201/1, EP/S016147/1); The Royal Society (Grant Number(s): INF\R2\192052).An AlPO4 zeotype has been prepared using the aromatic diamine 1,10‐phenanthroline and some of its methylated analogues as templates. In each case the two template N atoms bind to a specific framework Al site to expand its coordination to the unusual octahedral AlO4N2 environment. Furthermore, using this framework‐bound template, Fe atoms can be included selectively at this site in the framework by direct synthesis, as confirmed by annular dark field scanning transmission electron microscopy and Rietveld refinement. Calcination removes the organic molecules to give large pore framework solids, with BET surface areas up to 540 m2 g‐1 and two perpendicular sets of channels that intersect to give pore space connected by 12‐ring openings along all crystallographic directions.Publisher PDFPeer reviewe

STA-20 : an ABC-6 zeotype structure prepared by co-templating and solved via a hypothetical structure database and STEM-ADF imaging

This work has been supported by Johnson Matthey PLC, UK. AEW acknowledges funding from an EPSRC/Johnson Matthey Industrial CASE PhD award EP/N50936X/1. We acknowledge Diamond Light Source for time on beamline I11 under the funded Proposal EE11830-1.A microporous silicoaluminophosphate with a novel topology type, STA-20, has been prepared via a dual templating method using hexamethylene bisdiazabicyclooctane (diDABCO-C6) and trimethylamine as co-templates. Its structure has been solved and confirmed using a multi-technique approach that included the use of a hypothetical zeolite database to obtain a candidate starting structure, followed by scanning transmission electron microscopy with annular dark field imaging and Rietveld refinement. STA-20 is a member of the ABC-6 family of zeotype structures. The structure has trigonal symmetry, P-31c, with a = 13.15497(18) Å and c = 30.5833(4) Å in the calcined form. It has a 12-layer stacking sequence of 6-rings (6Rs), AABAABAACAAC(A), which contains single and double 6R units. As well as d6r, can and gme cages, STA-20 possesses the longest cage observed in an ordered ABC-6 material, giving a 3D-connected pore system limited by 8R windows. Models for the location of the templates within cages of the framework were obtained by combining elemental analysis, 13C MAS NMR, computer modelling and Rietveld refinement.PostprintPostprintPeer reviewe