Adsorption of Argon, Methane, Nitrogen, Carbon Monoxide and Water Vapour on Sepiolite and Alpo4-5 as Studied by Isothermal Microcalorimetry

Sorption Properties of AlPO4-5 and SAPO-5 Zeolite-like Materials

“…The isotherms measured at T = 77.3 K concerning both AlPO 4 -5 (sample D) and SAPO-5 (sample B) are characterized by a substep located at low relative pressure P sub / P o = 4.2 ×10 -3 , Figure a ( P sub and P o are the pressure of the substep and the methane saturated pressure, respectively). Such an isotherm substep has been observed for the first time by Grillet et al. − It was interpreted as a sorbed phase transition, presumably a crystallization of the methane sorbate. Indeed, a heat peak is observed in the microcalorimetric signal of the methane sorbed phase during the substep formation. , Recently, the phase transition has been confirmed by molecular simulation by Boutin et al The AlPO 4 -5 samples used in the two experimental studies 9,10 are of the same origin as our sample A.…”

“…Such an isotherm substep has been observed for the first time by Grillet et al. − It was interpreted as a sorbed phase transition, presumably a crystallization of the methane sorbate. Indeed, a heat peak is observed in the microcalorimetric signal of the methane sorbed phase during the substep formation. , Recently, the phase transition has been confirmed by molecular simulation by Boutin et al The AlPO 4 -5 samples used in the two experimental studies 9,10 are of the same origin as our sample A. We have observed that the isotherm substep is more developed and vertical for the AlPO 4 -5 sample D, which presents the highest sorption capacity (around six methane molecules by unit cell), Figure .…”

“…The sorption isotherms have the usual type I shape, while water, which is a more complex sorbate, presents a type V isotherm shape. More recently, Grillet et al have measured a methane sorption isotherm characterized by a substep existence in the high-loading regime. In addition, an exothermic heat peak is observed at the same CH 4 sorbed quantity. , Hitherto, such phase transitions in sorbate species have been pointed out only during the sorption of simple gases (i.e., Ar, Kr, N 2 , and CO) in silicalite-I. − Silicalite-I, which is the pure silicic form of the MFI-type zeolite, has a rather complex inner surface composed of at least three kinds of sorption sites and a complex micropore network constituted of straight channels and sinusoidal channels.…”

Sustainable preparation of a novel glycerol-free biofuel by using pig pancreatic lipase: Partial 1,3-regiospecific alcoholysis of sunflower oil

“…The channels (11.5 Å Â 5.3 Å ) that move along the fibres confer the solid a microporous structure with a high surface area, similar to that of the AlPO-5 [62][63][64]. The extraction of the ions (i.e.…”

Molecular Simulation Study of the Structural Rearrangement of Methane Adsorbed in Aluminophosphate AlPO4-5

“…Recently, unexpected adsorption isotherm behavior, such as isotherm steps and hysteresis, more commonly associated with mesoporous materials, has been observed for specific adsorbates in several molecular sieves. While in most cases the amount of gas adsorbed in the microporous crystal increases regularly with the surrounding pressure, in some specific examples, for instance argon, krypton, and nitrogen adsorbed in Silicalite I − and methane in aluminophosphate AlPO 4 -5, − the adsorption isotherms exhibit a substep at a pressure well below the saturation vapor pressure. These substep phenomena are accompanied by a characteristic isosteric heat of adsorption signal.…”