Diffusion in nanopores: inspecting the grounds

Kärger, Jörg; Ruthven, Douglas M.; Valiullin, Rustem

doi:10.1007/s10450-020-00277-6

Cited by 23 publications

(18 citation statements)

References 116 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thanks to Shamsuzzaman Farooq (left in the top row), Editor in Chief of the Adsorption journal at that time, we had the opportunity to publish a collection of articles on the individual measurement methods and an introduction into diffusion theory in a special volume of the journal. This first step towards the final goal, namely the condensation of its contents towards a coherent treatise, including an introduction to the fundamentals of diffusion theory [82], has meanwhile been made [83][84][85].…”

Section: Diffusion In the Focus Of Iupacmentioning

confidence: 99%

Douglas M. Ruthven: In Memoriam of a Great Scholar and a Caring Friend

Kärger

2022

Chemie Ingenieur Technik

Self Cite

View full text Add to dashboard Cite

In September 2021, Professor Douglas Morris Ruthven, one of the pioneers of sorption research, passed away completely unexpectedly. The many research areas he has enriched with his contributions include, in particular, the field of diffusion, i.e., the random movement of guest diffusion in nanoporous materials. When NMR diffusometry was first used to study this phenomenon almost half a century ago, discrepancies of up to several orders of magnitude were revealed compared to the values so far generally accepted. Since then, the study of diffusion in nanoporous materials has been a hot topic in sorption research. The essay reports the great merits Doug Ruthven has earned in his life's work in this field. His activities include the refinement of existing and the development of novel measuring techniques just as their application or revealing the governing processes of mass transfer in a given nanoporous host‐guest system. The essay is, above all, a personal thank you from the author to Professor Ruthven for whom initial discrepancies in research results were not cause for quarrels and arguing but for a lifelong friendship.

show abstract

Section: Diffusion In the Focus Of Iupacmentioning

confidence: 99%

Douglas M. Ruthven: In Memoriam of a Great Scholar and a Caring Friend

Kärger

2022

Chemie Ingenieur Technik

Self Cite

View full text Add to dashboard Cite

show abstract

“…It refers to those techniques that necessitate a non-equilibrium situation as non-equilibrium techniques, and to the remaining ones as equilibrium techniques. An introduction to the various possibilities of measurement and the resulting physical parameters may be found in [107] and their theoretical foundation and correlation in [101].…”

Section: Equilibrium Vs Non-equilibriummentioning

confidence: 99%

“…The thus defined self-(or tracer) diffusivity may also be shown to (completely equivalently!) result from Einstein's famous diffusion equation (see, e.g., [107] or Sect. 2.1.3 of [26]) as the factor of proportionality between the molecular mean square displacement and (six times) the observation time.…”

Section: Equilibrium Vs Non-equilibriummentioning

confidence: 99%

Diffusion in Nanoporous Solids in the Focus of IUPAC – A Tribute to Jens Weitkamp

Gläser

Kärger

Ruthven

2021

Chemie Ingenieur Technik

Self Cite

View full text Add to dashboard Cite

In bidding farewell to Prof. Dr.-Ing. Jens Weitkamp, we remember his many activities and his beneficial influence on the development of science, notably in the various fields of chemical technology and engineering. These activities include his engagement in support of the development of techniques dedicated to improvement of our understanding of the complex phenomenon of mass transfer in nanoporous materials, as both an ingenious scientist and a brilliant organizer and gifted leader of scientific alliances. The present contribution provides a brief introduction to the many facets of research in this field, with particular recognition of the most recent developments and Prof. Weitkamp's contributions.

show abstract

“…A consensus on the role of Brønsted acidity in the first C-C bond formation mechanism from C1 methanol molecule has emerged [4,[6][7][8][9][10]. However, studies on the initial stage of the MTH process involving adsorption, diffusion and reaction of molecules at the Brønsted acid site are very limited [12][13][14][15][16]; and as diffusion rates often determine the reaction rates, the understanding of diffusion dynamics is crucial for designing and tailoring further the acidity and porous architecture for the development of an efficient catalytic process [17]. In this perspective, we discuss in detail the effect of acid site density, which in turn depends on the Si/Al ratio of ZSM-5, on the methanol diffusion dynamics and show how the combination of experimental neutron scattering studies with molecular simulations can reveal the complexity of the dynamical behaviour of sorbed methanol in the pores of zeolite ZSM-5.…”

Section: Introductionmentioning

confidence: 99%

Methanol diffusion and dynamics in zeolite H-ZSM-5 probed by quasi-elastic neutron scattering and classical molecular dynamics simulations

Matam,

Silverwood,

Boudjema

et al. 2023

Phil. Trans. R. Soc. A.

View full text Add to dashboard Cite

Zeolite ZSM-5 is a key catalyst in commercially relevant processes including the widely studied methanol to hydrocarbon reaction, and molecular diffusion in zeolite pores is known to be a crucial factor in controlling catalytic reactions. Here, we present critical analyses of recent quasi-elastic neutron scattering (QENS) data and complementary molecular dynamics (MD) simulations. The QENS experiments show that the nature of methanol diffusion dynamics in ZSM-5 pores is dependent both on the Si/Al ratio (11, 25, 36, 40 and 140), which determines the Brønsted acid site density of the zeolite, and that the nature of the type of motion observed may vary qualitatively over a relatively small temperature range. At 373 K, on increasing the ratio from 11 to 140, the observed mobile methanol fraction increases and the nature of methanol dynamics changes from rotational (in ZSM-5 with Si/Al of 11) to translational diffusion. The latter is either confined localized diffusion within a pore in zeolites with ratios up to 40 or non-localized, longer-range diffusion in zeolite samples with the ratio of 140. The complementary MD simulations conducted over long time scales (1 ns), which are longer than those measured in the present study by QENS (≈1–440 ps), at 373 K predict the occurrence of long-range translational diffusion of methanol in ZSM-5, independent of the Si/Al ratios (15, 47, 95, 191 and siliceous MFI). The rate of diffusion increases slightly by increasing the ratio from 15 to 95 and thereafter does not depend on zeolite composition. Discrepancies in the observed mobile methanol fraction between the MD simulations (100% methanol mobility in ZSM-5 pores across all Si/Al ratios) and QENS experiments (for example, ≈80% immobile methanol in ZSM-5 with Si/Al of 11) are attributed to the differences in time resolutions of the techniques. This perspective provides comprehensive information on the effect of acid site density on methanol dynamics in ZSM-5 pores and highlights the complementarity of QENS and MD, and their advantages and limitations. This article is part of the theme issue ‘Exploring the length scales, timescales and chemistry of challenging materials (Part 2)’.

show abstract

Diffusion in nanopores: inspecting the grounds

Cited by 23 publications

References 116 publications

Douglas M. Ruthven: In Memoriam of a Great Scholar and a Caring Friend

Douglas M. Ruthven: In Memoriam of a Great Scholar and a Caring Friend

Diffusion in Nanoporous Solids in the Focus of IUPAC – A Tribute to Jens Weitkamp

Methanol diffusion and dynamics in zeolite H-ZSM-5 probed by quasi-elastic neutron scattering and classical molecular dynamics simulations

Contact Info

Product

Resources

About