arXiv subjects

Sergei S. Arzumanov

Publications and source records attributed to Sergei S. Arzumanov.

3 recordsLinked to original sources

arXiv2021

Impact of OH-groups on the mobility of linkers and guests in UiO-66 (Zr)

UiO-66 (Zr) is a metal-organic framework known for its thermal and chemical stability and wide range of possible applications. In particular, this material has high separation selectivity of various hydrocarbon mixtures. Moreover, it is was shown that the performance depends on the hydroxylation state of material (reversible phase transition $Zr_{6}O_{4}(OH)_{4} {\longrightarrow} Zr_{6}O_{6}$ at 250 - 300 $°C)$. Despite all the attention the UiO-66 received over past few years, the impact of the dehydroxylation on its properties remains poorly understood. In this contribution we apply $^{2}$H NMR experimental method in order to compare the mobility of butane isomers in hydroxylated and dehydroxylated form of UiO-66. We provide estimations of the translational diffusion coefficients and show which hydroxylation state of the material has higher separation selectivity. Moreover, the impact of the hydroxylation on the structural mobility of UiO-66 is discussed. Correlation between parameters of structural dynamics and the diffusivity of guest molecules indicates that for the microporous material with small windows even subtle changes can lead to a tangible improvement of the properties.

cond-mat.mtrl-sci↗

arXiv2020

Evidence of the kinetic-driven separation of butane isomers in UiO-66 (Zr) MOF, a combined experimental and computational study

UiO-66 is a well-known metal organic framework that proved to be promising for various separation applications. In this report we study the molecular mobility and transport of n-butane and isobutane through the UiO-66. We show that n-butane propagates through the material significantly faster than isobutane both in terms of energetics (diffusion barrier is 25 kJ mol-1 for n-butane and 50 kJ mol-1 for isobutane) and rate (Di(303 K)/Dn(303 K) = 1700). This result allows expecting very high kinetic driven separation selectivity of n-butane/isobutane mixture in UiO-66.

cond-mat.mtrl-sci↗

arXiv2020

Dynamics of Butane and 1-Butene in ZIF-8 Probed by Solid-State 2H NMR

We present a detailed $^{2}$H NMR characterization of molecular mobility of 1-butene and n-butane propagating through the microporous ZIF-8, a zeolitic imidazolate framework renowned for its outstandingly high stability and separation selectivity of various. The experimental characterization of n-butane and 1-butene diffusivity in ZIF-8 on the molecular scale is provided for the first time. With $^{2}$H NMR spin relaxation analysis we have elucidated the motional mechanism for 1-butene and n-butane guests trapped within ZIF-8 framework and derived kinetic parameters for each type of motion. The characteristic times for microscopic translational diffusion and activation barriers (E$_{C4H10}$ = 34 kJ mol$^{-1}$, E$_{C4H8}$ = 32 kJ mol$^{-1}$) for n-butane and 1-butene diffusivities have been elucidated. Finally, we show that $^{2}$H NMR technique is capable to provide reliable information on microscopic diffusivity in the ZIF-8 MOF even for molecules with slow diffusion rates (<10$^{-14} m^{2} s^{-1}$).

physics.chem-ph↗