Mapping the dynamics of methanol and xenon co-adsorption in SWNTs by in situ continuous-flow hyperpolarized 129Xe NMR

Abstract

A comparative study of the adsorption and desorption processes of methanol in two kinds of nanochannels (i.e. MCM-41 and SWNTs) is performed by in situ continuous-flow laser-hyperpolarized ¹²⁹Xe NMR. The high sensitivity and short acquisition time of hyperpolarized ¹²⁹Xe allow for probing the molecular dynamics in a confined geometry under real working conditions. Hyperpolarized ¹²⁹Xe NMR spectra indicate that the methanol adsorption behavior in nanochannels is determined by the characters of adsorption sites and that the methanol adsorption rate in the nanochannels of SWNTs is faster than in MCM-41. The experimental data shown in this work also indicate that there is a change in gas phase ¹²⁹Xe NMR signal intensity during the adsorption and desorption of methanol in SWNTs. This may be because there is a strong depolarization of hyperpolarized ¹²⁹Xe in SWNTs.