Possibility of quantum effect in micropore filling of Ne on AlPO4-5

Adsorption isotherms of neon at 27, 30, and 33 K on aluminophosphate AlPO4-5 were measured. The experimental adsorption isotherms and isosteric heat of adsorption for neon on AlPO4-5 were compared with those calculated from the density functional theory (DFT) treating the classical Lennard-Jones systems. The classical DFT results exhibited the first layer filling on the pore wall and the second filling in the center of the pore. However the experimental isotherms showed only one layer transition, suggesting that quantum contributions cannot be neglected for neon adsorption on the micropores of AlPO4-5 at low temperatures.