Adsorption of hydrogen and deuterium in MnO2 modified NaX zeolites

Abstract: MnO2 modified NaX zeolites are prepared by dispersion of MnO2 on the surface of NaX in a calcination process. XRD, XPS and N2 adsorption tests confirm that the dispersed MnO2 is primarily monolayer and the calcination conditions affect the dispersion efficiency. The adsorption performances of hydrogen and deuterium of the modified zeolites are investigated at both 77K and 295K. A hydrogen adsorption capacity increase up to 30% is observed at 295K for NaX with moderate MnO2 modification, but the corresponding adsorption at 77K does not show much improvement, and even deteriorates for the samples with high MnO2 contents. NaX shows an adsorption capacity difference of 11% between hydrogen and deuterium at 9bar and 77K, higher than that of MnO2 modified samples (4%); while the difference is much smaller at 295K for all samples. The effects of MnO2 modification on hydrogen adsorption properties are explained by the involvement of Kubas interaction, where Mn in MnO2 acts as a d-electron donor for the enhanced binding of hydrogen molecules. [Copyright &y& Elsevier]