The methanol-to-hydrocarbons reaction refers collectively to a series of important industrial catalytic processes to produce either olefins or gasoline. Mechanistically, methanol conversion proceeds through a ‘pool’ of hydrocarbon species. For the methanol-to-olefins process, these species can be delineated broadly into ‘desired’ lighter olefins and ‘undesired’ heavier fractions that cause deactivation in a matter of hours. The crux in further catalyst optimization is the ability to follow the formation of carbonaceous species during operation. Here, we report the combined results of an operando Kerr-gated Raman spectroscopic study with state-of-the-art operando molecular simulations, which allowed us to follow the formation of hydrocarbon species at various stages of methanol conversion. Polyenes are identified as crucial intermediates towards formation of polycyclic aromatic hydrocarbons, with their fate determined largely by the zeolite topology. Notably, we provide the missing link between active and deactivating species, which allows us to propose potential design rules for future-generation catalysts.
Subscribe to Journal
Get full journal access for 1 year
only $17.42 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
Source data are provided with this paper. Example CP2K input files and processing scripts are available from the public GitHub online repository at https://github.com/AlexanderHoffman/supporting-info. Owing to the large size of the molecular dynamics trajectories and CP2K output files, they are available upon author request instead.
Olsbye, U. et al. Conversion of methanol to hydrocarbons: how zeolite cavity and pore size controls product selectivity. Angew. Chem. Int. Ed. 51, 5810–5831 (2012).
Yarulina, I., Chowdhury, A. D., Meirer, F., Weckhuysen, B. M. & Gascon, J. Recent trends and fundamental insights in the methanol-to-hydrocarbons process. Nat. Catal. 1, 398–411 (2018).
Yarulina, I. et al. Structure–performance descriptors and the role of Lewis acidity in the methanol-to-propylene process. Nat. Chem. 10, 804–812 (2018).
Olsbye, U. et al. The formation and degradation of active species during methanol conversion over protonated zeotype catalysts. Chem. Soc. Rev. 44, 7155–7176 (2015).
Hereijgers, B. P. C. et al. Product shape selectivity dominates the methanol-to-olefins (MTO) reaction over H-SAPO-34 catalysts. J. Catal. 264, 77–87 (2009).
Bleken, F. et al. The effect of acid strength on the conversion of methanol to olefins over acidic microporous catalysts with the CHA topology. Top. Catal. 52, 218–228 (2009).
Dahl, I. M. & Kolboe, S. On the reaction mechanism for hydrocarbon formation from methanol over SAPO-34: I. Isotopic labeling studies of the co-reaction of ethene and methanol. J. Catal. 149, 458–464 (1994).
Dahl, I. M. & Kolboe, S. On the reaction mechanism for hydrocarbon formation from methanol over SAPO-34: 2. Isotopic labeling studies of the co-reaction of propene and methanol. J. Catal. 161, 304–309 (1996).
Bjørgen, M. et al. Spectroscopic evidence for a persistent benzenium cation in zeolite H-beta. J. Am. Chem. Soc. 125, 15863–15868 (2003).
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).
Fu, H., Song, W. & Haw, J. F. Polycyclic aromatics formation in HSAPO-34 during methanol-to-olefin catalysis: ex situ characterization after cryogenic grinding. Catal. Lett. 76, 89–94 (2001).
Li, C. et al. Synthesis of reaction‐adapted zeolites as methanol-to-olefins catalysts with mimics of reaction intermediates as organic structure‐directing agents. Nat. Catal. 1, 547–554 (2018).
Arora, S. S., Nieskens, D. L. S., Malek, A. & Bhan, A. Lifetime improvement in methanol-to-olefins catalysis over chabazite materials by high-pressure H2 co-feeds. Nat. Catal. 1, 666–672 (2018).
Hunger, M., Seiler, M. & Buchholz, A. In situ MAS NMR spectroscopic investigation of the conversion of methanol to olefins on silicoaluminophosphates SAPO-34 and SAPO-18 under continuous flow conditions. Catal. Lett. 74, 61–68 (2001).
Wang, W., Buchholz, A., Seiler, M. & Hunger, M. Evidence for an initiation of the methanol-to-olefin process by reactive surface methoxy groups on acidic zeolite catalysts. J. Am. Chem. Soc. 125, 15260–15267 (2003).
Dai, W. et al. Understanding the early stages of the methanol-to-olefin conversion on H-SAPO-34. ACS Catal. 5, 317–326 (2015).
Wang, C. et al. Experimental evidence on the formation of ethene through carbocations in methanol conversion over H-ZSM-5 zeolite. Chem. Eur. J. 21, 12061–12068 (2015).
Chua, Y. T. & Stair, P. C. An ultraviolet Raman spectroscopic study of coke formation in methanol to hydrocarbons conversion over zeolite H-MFI. J. Catal. 213, 39–46 (2003).
Beato, P., Schachtl, E., Barbera, K., Bonino, F. & Bordiga, S. Operando Raman spectroscopy applying novel fluidized bed micro-reactor technology. Catal. Today 205, 128–133 (2013).
Signorile, M. et al. Topology-dependent hydrocarbon transformations in the methanol-to-hydrocarbons reaction studied by operando UV-Raman spectroscopy. Phys. Chem. Chem. Phys. 20, 26580–26590 (2018).
Howe, R. F. et al. Reactions of dimethylether in single crystals of the silicoaluminophosphate STA-7 studied via operando synchrotron infrared microspectroscopy. Top. Catal. 61, 199–212 (2018).
Qian, Q. et al. Combined operando UV/Vis/IR spectroscopy reveals the role of methoxy and aromatic species during the methanol-to-olefins reaction over H-SAPO-34. ChemCatChem. 6, 3396–3408 (2014).
Borodina, E. et al. Influence of the reaction temperature on the nature of the active and deactivating species during methanol to olefins conversion over H-SSZ-13. ACS Catal. 5, 992–1003 (2015).
Goetze, J. et al. Insights into the activity and deactivation of the methanol-to-olefins process over different small-pore zeolites as studied with operando UV–vis spectroscopy. ACS Catal. 7, 4033–4046 (2017).
Lesthaeghe, D., Horré, A., Waroquier, M., Marin, G. B. & Van Speybroeck, V. Theoretical insights on methylbenzene side-chain growth in ZSM-5 zeolites for methanol-to-olefin conversion. Chem. Eur. J. 15, 10803–10808 (2009).
Forester, T. R. & Howe, R. F. In situ FTIR studies of methanol and dimethyl ether in ZSM-5. J. Am. Chem. Soc. 109, 5076–5082 (1987).
Stair, P. C. The application of UV Raman spectroscopy for the characterization of catalysts and catalytic reactions. Adv. Catal. 51, 75–98 (2007).
Kim, H., Kosuda, K. M., Van Duyne, R. P. & Stair, P. C. Resonance Raman and surface- and tip-enhanced Raman spectroscopy methods to study solid catalysts and heterogeneous catalytic reactions. Chem. Soc. Rev. 39, 4820–4844 (2010).
Matousek, P., Towrie, M., Stanley, A. & Parker, A. W. Efficient rejection of fluorescence from Raman spectra using picosecond Kerr gating. Appl. Spectrosc. 53, 1485–1489 (1999).
Matousek, P., Towrie, M. & Parker, A. W. Fluorescence background suppression in Raman spectroscopy using combined Kerr gated and shifted excitation Raman difference techniques. J. Raman Spectrosc. 33, 238–242 (2002).
Blaszkowski, S. R. & van Santen, R. A. The mechanism of dimethyl ether formation from methanol catalyzed by zeolitic protons. J. Am. Chem. Soc. 118, 5152–5253 (1996).
Allotta, P. M. & Stair, P. C. Time-resolved studies of ethylene and propylene reactions in zeolite H-MFI by in-situ fast IR heating and UV Raman spectroscopy. ACS Catal. 2, 2424–2432 (2012).
Socrates, G. Infrared and Raman Characteristic Group Frequencies 3rd edn (Wiley, 2004).
Ghysels, A. et al. Shape-selective diffusion of olefins in 8-ring solid acid microporous zeolites. J. Phys. Chem. C 119, 23721–23734 (2015).
Tinnemans, S. J., Kox, M. H. F., Nijhuis, T. A., Visser, T. & Weckhuysen, B. M. Real time quantitative Raman spectroscopy of supported metal oxide catalysts without the need of an internal standard. Phys. Chem. Chem. Phys. 7, 211–216 (2005).
Bjørgen, M. et al. Conversion of methanol to hydrocarbons over zeolite H-ZSM-5: on the origin of the olefinic species. J. Catal. 249, 195–207 (2007).
Database of Zeolite Structures http://www.iza-structure.org/databases (2017).
Mores, D. et al. Space- and time-resolved in-situ spectroscopy on the coke formation in molecular sieves: methanol-to-olefin conversion over H-ZSM-5 and H-SAPO-34. Chem. Eur. J. 14, 11320–11327 (2008).
Borodina, E. et al. Influence of the reaction temperature on the nature of the active and deactivating species during methanol-to-olefins conversion over H-SAPO-34. ACS Catal. 7, 5268–5281 (2017).
Hwang, A., Kumar, M., Rimer, J. D. & Bhan, A. Implications of methanol disproportionation on catalyst lifetime for methanol-to-olefins conversion by HSSZ-13. J. Catal. 346, 154–160 (2017).
Li, Y., Yu, J. & Xu, R. Criteria for zeolite frameworks realizable for target synthesis. Angew. Chem. Int. Ed. 52, 1673–1677 (2013).
Li, Y. & Yu, J. New stories of zeolite structures: their descriptions, determinations, predictions, and evaluations. Chem. Rev. 114, 7268–7316 (2014).
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).
Lezcano-Gonzalez, I. et al. Determining the storage, availability and reactivity of NH3 within Cu–chabazite-based ammonia selective catalytic reduction systems. Phys. Chem. Chem. Phys. 16, 1639–1650 (2014).
Hutter, J., Iannuzzi, M., Schiffmann, F. & VandeVondele, J. CP2K: atomistic simulations of condensed matter systems. Wiley Interdiscip. Rev. Comput. Mol. Sci. 4, 15–25 (2014).
Lippert, G., Hutter, J. & Parrinello, M. The Gaussian and augmented-plane-wave density functional method for ab initio molecular dynamics simulations. Theor. Chem. Acc. 103, 124–140 (1999).
Yang, K., Zheng, J., Zhao, Y. & Truhlar, D. G. Tests of the RPBE, revPBE, τ-HCTHhyb, ωB97X-D, and MOHLYP density functional approximations and 29 others against representative databases for diverse bond energies and barrier heights in catalysis. J. Chem. Phys. 132, 164117 (2010).
Goedecker, S., Teter, M. & Hutter, J. Separable dual-space Gaussian pseudopotentials. Phys. Rev. B 54, 1703–1710 (1996).
Cnudde, P. et al. How chain length and branching influence the alkene cracking reactivity on H-ZSM-5. ACS Catal. 8, 9579–9595 (2018).
Frenkel, D. & Smit, B. Understanding Molecular Simulation 2nd edn (Academic Press, 2002).
Luber, S., Iannuzzi, M. & Hutter, J. Raman spectra from ab initio molecular dynamics and its application to liquid S-methyloxirane. J. Chem. Phys. 141, 094503 (2014).
Thomas, M., Brehm, M., Fligg, R., Vöhringer, P. & Kirchner, B. Computing vibrational spectra from ab initio molecular dynamics. Phys. Chem. Chem. Phys. 15, 6608–6622 (2013).
This research has been performed with the use of facilities including a Raman spectrometer and thermogravimetric analysis equipment at the Research Complex at Harwell. We thank the Research Complex for access and support to these facilities and equipment. We acknowledge the Engineering and Physical Sciences Research Council for funding grants EP/K007467/1, EP/K014706/2, EP/K014668/1, EP/K014854/1, EP/K014714/1, EP/M013219/1, EP/S016481/1 and EP/S016481/1. The Science and Technology Facilities Council (STFC) is acknowledged for the beam time at the ULTRA facility for performing Kerr-gate experiments. L. Mantarosie (Johnson Matthey PLC) is also thanked for her assistance and expertise. P. Matousek and T. Parker (STFC) are acknowledged for useful discussions. V.V.S., A.E.J.H. and M.B. acknowledge the Research Foundation – Flanders (FWO), the Special Research Fund of Ghent University, and funding from the Horizon 2020 research and innovation program of the European Union (consolidator European Research Council grant agreement no. 647755 – DYNPOR (2015–2020)). The computational resources and services were provided by Ghent University (Stevin Supercomputer Infrastructure) and the Flemish Supercomputer Center, and funded by the FWO.
The authors declare no competing interests.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Processed Kerr-gated Raman data recorded during the MTH reaction between 250 and 300 °C on SSZ-13 zeolite; processed mass spectrometry data recorded during the MTH reaction between 240 and 310 °C on SSZ-13 zeolite.
Comparison between processed Kerr-gated Raman data recorded during the MTH reaction at 260, 280 and 300 °C and the simulated spectra of propene, isoprene, butadiene, trimethylnaphthalene, trimethylbenzene, dimethylpentadiene and heptatriene.
Position of the centre of mass of the carbon atoms projected on one of the 8-ring channels and a direction perpendicular to it for the intermediates propene, heptatriene and decapentaene.
Processed Kerr-gated Raman data recorded during the MTH reaction between 320 and 450 °C on SSZ-13 zeolite; simulated Raman spectra of anthracene and anthracene precursor; processed Kerr-gated Raman data recorded after quenching the MTH reaction at 450 °C in SSZ-13, ZSM-5 and SAPO-34 catalyst materials.
Processed Kerr-gated Raman data recorded before and after methanol adsorption at 100 °C on SSZ-13 zeolite.
Processed Kerr-gated Raman data recorded during the MTH reaction between 100 and 240 °C on SSZ-13 zeolite; processed mass spectrometry data recorded during the MTH reaction between 100 and 250 °C on SSZ-13 zeolite.
Processed Kerr-gated Raman data recorded during the MTH reaction on SSZ-13 zeolite under isothermal conditions at 280 and 350 °C; processed mass spectrometry data recorded during the MTH reaction on SSZ-13 zeolite under isothermal conditions at 280 and 350 °C.
Processed Kerr-gated Raman data recorded during the MTH reaction between 280 and 340 °C on ZSM-5 zeolite; processed mass spectrometry data recorded during the MTH reaction between 260 and 350 °C on ZSM-5 zeolite; processed Kerr-gated Raman data recorded during the MTH reaction between 360 and 450 °C on ZSM-5 zeolite.
Processed Kerr-gated Raman data recorded during the MTH reaction between 210 and 450 °C on SAPO-34; processed mass spectrometry data recorded during the MTH reaction between 250 and 350 °C on SAPO-34.
Processed Raman data recorded using a lab-based Raman spectrometer (830 nm) for SSZ-13 zeolite after the MTH reaction at 450 °C and for Mo/H-ZSM-5 zeolite after methane dehydroaromatization at 700 °C for 30 h (GHSV 1500 h−1).
Thermogravimetric analysis of SSZ-13 zeolite after the MTH reaction at 450 °C.
About this article
Cite this article
Lezcano-Gonzalez, I., Campbell, E., Hoffman, A.E.J. et al. Insight into the effects of confined hydrocarbon species on the lifetime of methanol conversion catalysts. Nat. Mater. 19, 1081–1087 (2020). https://doi.org/10.1038/s41563-020-0800-y