Synthesis of reaction-adapted zeolites as methanol-to-olefins catalysts with mimics of reaction intermediates as organic structure-directing agents

[EN] Catalysis with enzymes and zeolites have in common the presence of well-defined single active sites and pockets/cavities where the reaction transition states can be stabilized by longer-range interactions. We show here that for a complex reaction, such as the conversion of methanol-to-olefins (MTO), it is possible to synthesize reaction-adapted zeolites by using mimics of the key molecular species involved in the MTO mechanism. Effort has focused on the intermediates of the paring mechanism because the paring is less favoured energetically than the side-chain route. All the organic structure-directing agents based on intermediate mimics crystallize cage-based small-pore zeolitic materials, all of them capable of performing the MTO reaction. Among the zeolites obtained, RTH favours the whole reaction steps following the paring route and gives the highest propylene/ethylene ratio compared to traditional CHA-related zeolites (3.07 and 0.86, respectively).Li, C.; Paris, C.; Martínez-Triguero, J.; Boronat Zaragoza, M.; Moliner Marin, M.; Corma Canós, A. (2018). Synthesis of reaction-adapted zeolites as methanol-to-olefins catalysts with mimics of reaction intermediates as organic structure-directing agents. Nature Catalysis. 1(7):547-554. https://doi.org/10.1038/s41929-018-0104-7S54755417Stocker, M. Methanol-to-hydrocarbons: catalytic materials and their behavior. Micro. Mesopor. Mater. 29, 3–48 (1999).Tian, P., Wei, Y., Ye, M. & Liu, Z. Methanol to olefins (MTO): from fundamentals to commercialization. ACS Catal. 5, 1922–1938 (2015).Ilias, S. & Bhan, A. Mechanism of the catalytic conversion of methanol to hydrocarbons. ACS Catal. 3, 18–31 (2013).Olsbye, U. et al. Conversion of methanol to hydrocarbons: how zeolite cavity and pore size controls product selectivity. Angew. Chem. Int. Ed. 24, 5810–5831 (2012).Hemelsoet, K., Van der Mynsbrugge, J., De Wispelaere, K., Waroquier, M. & Van Speybroeck, V. Unraveling the reaction mechanisms governing methanol-to-olefins catalysis by theory and experiment. ChemPhysChem 14, 1526–1545 (2013).Song, W., Haw, J. F., Nicholas, J. B. & Heneghan, C. S. Methylbenzenes are the organic reaction centers for methanol-to-olefin catalysis on HSAPO-34. J. Am. Chem. Soc. 122, 10726–10727 (2000).Arstad, B. & Kolboe, S. The reactivity of molecules trapped within the SAPO-34 cavities in the methanol-to-hydrocarbons reaction. J. Am. Chem. Soc. 123, 8137–8138 (2001).Xu, T. et al. Synthesis of a benzenium ion in a zeolite with use of a catalytic flow reactor. J. Am. Chem. Soc. 120, 4025–4026 (1998).Song, W., Nicholas, J. B., Sassi, A. & Haw, J. F. Synthesis of the heptamethylbenzene cation in zeolite beta: in situ NMR and theory. Catal. Lett. 81, 49–53 (2002).Xu, S. et al. Direct observation of cyclic carbenium ions and their role in the catalytic cycle of the metahnol-to-olefin reaction over chabazite zeolites. Angew. Chem. Int. Ed. 52, 11564–11568 (2013).Chen, J. et al. Elucidating the olefin formation mechanism in the methanol to olefin reaction over AlPO-18 and SAPO-18. Catal. Sci. Tech. 4, 3268–3277 (2014).Haw, J. F. et al. Roles for cyclopentenyl cations in the synthesis of hydrocarbons from methanol on zeolite catalyst HZSM-5. J. Am. Chem. Soc. 122, 4763–4775 (2000).Svelle, S. et al. Conversion of methanol into hydrocarbons over zeolite H-ZSM-5: ethene formation is mechanistically separated from the formation of higher alkenes. J. Am. Chem. Soc. 128, 14770–14771 (2006).Teketel, S., Olsbye, U., Lillerud, K. P., Beato, P. & S., S. Selectivity control through fundamental mechanistic insight in the conversion of methanol to hydrocarbons over zeolites. Micro. Mesopor. Mater. 136, 33–41 (2010).Zhang, M. et al. Methanol conversion on ZSM-22, ZSM-35 and ZSM-5 zeolites: effects of 10-membered ring zeolite structures on methylcyclopentenyl cations and dual cycle mechanism. RSC Adv. 6, 95855–95864 (2016).Sassi, A. et al. Methylbenzene chemistry on zeolite HBeta: multiple insights into methanol-to-olefin catalysis. J. Phys. Chem. B 106, 2294–2303 (2002).Sassi, A., Wildman, M. A. & Haw, J. F. Reactions of butylbenzene isomers on zeolite HBeta: methanol-to-olefins hydrocarbon pool chemistry and secondary reactions of olefins. J. Phys. Chem. B 106, 8768–8773 (2002).Bjørgen, M., Olsbye, U., Petersen, D. & Kolboe, S. The methanol-to-hydrocarbons reaction: insight into the reaction mechanism from [12C]benzene and [13C]methanol coreactions over zeolite H-beta. J. Catal. 221, 1–10 (2004).McCann, D. M. et al. A complete catalytic cycle for supramolecular methanol-to-olefins conversion by linking theory with experiment. Angew. Chem. Int. Ed. 47, 5179–5182 (2008).Arstad, B., Kolboe, S. & Swang, O. Theoretical study of the heptamethylbenzenium ion. intramolecular isomerizations and C2, C3, C4 alkene elimination. J. Phys. Chem. A 109, 8914–8922 (2005).De Wispelaere, K., Hemelsoet, K., Waroquier, M. & Van Speybroeck, V. Complete low-barrier side-chain route for olefin formation during methanol conversion in H-SAPO-34. J. Catal. 305, 76–80 (2013).Wang, C. M., Wang, Y. D. & Xie, Z. K. Verification of the dual cycle mechanism for methanol-to-olefin conversion in HSAPO-34: a methylbenzene-based cycle from DFT calculations. Catal. Sci. Technol. 4, 2631–2638 (2014).Wang, C. M., Wang, Y. D., Liu, H. X., Xie, Z. K. & Liu, Z. P. Theoretical insight into the minor role of paring mechanism in the methanol-to-olefins conversion within HSAPO-34 catalyst. Micro. Mesopor. Mater. 158, 264–271 (2012).Ilias, S. & Bhan, A. The mechanism of aromatic dealkylation in methanol-to-hydrocarbons conversion on H-ZSM-5: What are the aromatic precursors to light olefins? J. Catal. 311, 6–16 (2014).Erichsen, M. W. et al. Conclusive evidence for two unimolecular pathways to zeolite-catalyzed de-alkylation of the heptamethylbenzenium cation. ChemCatChem 7, 4143–4147 (2015).Bhawe, Y. et al. Effect of cage size on the selective conversion of methanol to light olefins. ACS Catal. 2, 2490–2495 (2012).Kang, J. H. et al. Further studies on how the nature of zeolite cavities that are bounded by small pores influences the conversion of methanol to light olefins. ChemPhysChem 19, 412–419 (2018).Martin, N. et al. Nanocrystalline SSZ-39 zeolite as an efficient catalyst for the methanol-to-olefin (MTO) process. Chem. Commun. 52, 6072–6075 (2016).Dusselier, M., Deimund, M. A., Schmidt, J. E. & Davis, M. E. Methanol-to-olefins catalysis with hydrothermally treated zeolite SSZ-39. ACS Catal. 5, 6078–6085 (2015).Yokoi, T., Yoshioka, M., Imai, H. & Tatsumi, T. Diversification of RTH-type zeolite and its catalytic application. Angew. Chem. Int. Ed. 48, 9884–9887 (2009).Ji, Y., Deimund, M. A., Bhawe, Y. & Davis, M. E. Organic-free synthesis of CHA-type zeolite catalysts for the methanol-to-olefins reaction. ACS Catal. 5, 4456–4465 (2015).Liu, M. et al. Differences in Al distribution and acidic properties between RTH-type zeolites synthesized with OSDAs and without OSDAs. Phys. Chem. Chem. Phys. 16, 4155–4164 (2014).Gallego, E. M. et al. “Ab initio” synthesis of zeolites for preestablished catalytic reactions. Science 355, 1051–1054 (2017).Zones, S. I. & Nakagawa, Y. Use of modified zeolites as reagents influencing nucleation in zeolite synthesis. Stud. Surf. Sci. Catal. 97, 45–52 (1995).Li, C., Moliner, M. & Corma, A. Building zeolites from pre-crystallized units: nanoscale architecture. Angew. Chem. Int. Ed. https://doi.org/10.1002/anie.201711422 (2018).Zones, S. I. Zeolite SSZ-13 and its method of preparation. US Patent 4,544,538 (1985).Li, Z., Navarro, M. T., Martínez-Triguero, J., Yu, J. & Corma, A. Synthesis of nano-SSZ-13 and its application in the reaction of methanol to olefins. Catal. Sci. Technol. 6, 5856–5863 (2016).Kumar, M., Luo, H., Román-Leshkov, Y. & Rimer, J. D. SSZ-13 crystallization by particle attachment and deterministic pathways to crystal size control. J. Am. Chem. Soc. 137, 13007–13017 (2015).Martínez-Franco, R., Cantin, A., Moliner, M. & Corma, A. Synthesis of the small pore silicoaluminophosphate STA-6 by using supramolecular self-assembled organic structure directing agents. Chem. Mater. 26, 4346–4353 (2014).Schmidt, J. E., Deimund, M. A., Xie, D. & Davis, M. E. Synthesis of RTH-type zeolites using a diverse library of imidazolium cations. Chem. Mater. 27, 3756–3762 (2015).Moliner, M., Franch, C., Palomares, E., Grill, M. & Corma, A. Cu–SSZ-39, an active and hydrothermally stable catalyst for the selective catalytic reduction of NOx. Chem. Commun. 48, 8264–8266 (2012).Zhao, Y. & Truhlar, D. G. The M06 suite of density functionals for main group thermochemistry, thermochemical kinetics, noncovalent interactions, excited states, and transition elements: two new functionals and systematic testing of four M06-class functionals and 12 other functionals. Theor. Chem. Acc. 120, 215–241 (2008).Ditchfield, R., Hehre, W. J. & Pople, J. A. Self-consistent molecular orbital methods. 9. Extended Gaussian-type basis for molecular-orbital studies of organic molecules. J. Chem. Phys. 54, 724–728 (1971).Hehre, W. J., Ditchfield, R. & Pople, J. A. Self-consistent molecular orbital methods. 12. Further extensions of Gaussian-type basis sets for use in molecular-orbital studies of organic-molecules. J. Chem. Phys. 56, 2257–2261 (1972).Frisch, M. J. et al. Gaussian 09, Revision C.01. (Gaussian, Wallingford, 2009).Van Speybroeck, V. et al. First principle chemical kinetics in zeolites: the methanol-to-olefin process as a case study. Chem. Soc. Rev. 43, 7326–7357 (2014)

The Rotterdam Study: 2012 objectives and design update

The Rotterdam Study is a prospective cohort study ongoing since 1990 in the city of Rotterdam in The Netherlands. The study targets cardiovascular, endocrine, hepatic, neurological, ophthalmic, psychiatric, dermatological, oncological, and respiratory diseases. As of 2008, 14,926 subjects aged 45 years or over comprise the Rotterdam Study cohort. The findings of the Rotterdam Study have been presented in over a 1,000 research articles and reports (see www.erasmus-epidemiology.nl/rotterdamstudy). This article gives the rationale of the study and its design. It also presents a summary of the major findings and an update of the objectives and methods

Management of nystagmus in children: A review of the literature and current practice in UK specialist services

Nystagmus is an eye movement disorder characterised by abnormal, involuntary rhythmic oscillations of one or both eyes, initiated by a slow phase. It is not uncommon in the UK and regularly seen in paediatric ophthalmology and adult general/strabismus clinics. In some cases, it occurs in isolation, and in others, it occurs as part of a multisystem disorder, severe visual impairment or neurological disorder. Similarly, in some cases, visual acuity can be normal and in others can be severely degraded. Furthermore, the impact on vision goes well beyond static acuity alone, is rarely measured and may vary on a minute-to-minute, day-to-day or month-to-month basis. For these reasons, management of children with nystagmus in the UK is varied, and patients report hugely different experiences and investigations. In this review, we hope to shine a light on the current management of children with nystagmus across five specialist centres in the UK in order to present, for the first time, a consensus on investigation and clinical management

Early depletion of contact system in patients with sepsis : a prospective matched control observational study

Activation of the contact system generates bradykinin from high-molecular-weight kininogen and has been suggested to participate in the pathophysiology of sepsis. To test this, we prospectively measured bradykinin and high-molecular-weight kininogen levels in a cohort of sepsis patients requiring intensive care. From 29 patients meeting criteria for sepsis or septic shock according to Sepsis-3, blood was sampled within 24 h and on the fourth day following admittance to intensive care. Patients planned for neurosurgery served as matched controls. Sequential organ failure assessment score and 90-day mortality was registered. Bradykinin levels (median [interquartile range]) were lower in sepsis patients (79 [62–172] pg/ml) compared to controls (130 [86–255] pg/ml, p < 0.025) and did not correlate with mortality or severity of circulatory derangement. High-molecular-weight kininogen levels were lower in sepsis patients (1.6 [0.8–4.8] densitometry units) compared to controls (4.4 [2.9–7.7] densitometry units, p < 0.001), suggesting previous contact system activation. High-molecular-weight kininogen levels were lower in non-survivors than survivors (p = 0.003) and negatively correlated to severity of circulatory derangement. We conclude that a role for bradykinin in later stages of severe sepsis must be challenged. Low high-molecular-weight kininogen concentrations suggest that the decrease in bradykinin is due to substrate depletion