Heat of adsorption of carbon dioxyde and ethene on zeolites a exchanged with Li+, Ni2+ and Cu2+

Abstract

Various contents of Li +, Ni 2+ or Cu z+ were introduced in zeolite NaA by conventional cation exchange. Crystal damages are observed on samples having suffered the lower pH.The heat of adsorption of CO2 and CzI-I4 was determined by isothermal calorimetry. Very high initial heats (100-120 kJ tool -1) are found in NaA as well as in Li + exchanged samples, perhaps due to chemisorption on alkaline cations; they vanish when Ni 2+ or Cu 2+ replaces more than 20% of Na +, in like manner with Co 2+ or Zn 2+. For the adsorption of C2H4, high initial heats are absent in the ease of NaA, but gradually appear when divalent cations are introduced.Apart from these strong initial values, the heats of adsorption present a plateau vs. the adsorbed amount. Abnormal low values at the plateau are indicative of crystal damages.

Adsorption of carbon dioxide by X zeolites exchanged with Ni2+ and Cr3+: isotherms and isosteric heat

“…Results consistent with these observations have been reported by others for CO 2 adsorption on X zeolite [38], Cu(x)A [34], Zn(x)A [39], Na-ZSM-5 [22], and Na-G [14]. The weak character of adsorbate-adsorbate interactions could be due, as mentioned before, to the physisorbed state of CO 2 .…”

“…This evolution was also reported in the case of CO 2 adsorption on Cu(x)X [20] and Cu(x)A [34]. The continuous decrease in isosteric heat with the introduction of Cr 3+ could be ascribed to a progressive weakening of electrostatic fields present within zeolitic cavities.…”

Isosteric heats of adsorption of carbon dioxide on zeolite MCM-22 modified by alkali metal cations

“…Numerous papers concerning CO 2 adsorption on zeolites A (Delaval and De Lara 1981;Amari et al 1991), faujasites X and Y (Barrer and Gibbons 1965;Khelifa et al 1999;Hasegawa et al 2001;Walton et al 2006;Plant et al 2006), mordenites (Amari et al 1992), ZSM-5 (Yamazaki et al 1993;Dunne et al 1996;Katoh et al 2000), and chabazites (Zhang et al 2008) can be found in the literature investigating CO 2 adsorption to determine the effect of the structure and cation type on the adsorption equilibrium and energetics of the adsorption process. Much research effort has been focused on the CO 2 adsorption on NaX and NaY at ambient temperature (Maurin et al 2005;Plant et al 2006Plant et al , 2007 and more recently in NaY and LiY at high temperatures ) using a combination of Grand Canonical Monte Carlo simulations and microcalorimetry/gravimetry measurements.…”

Chemisorption and physisorption of CO2 on cation exchanged zeolitesA, X and mor

“…On the contrary, the initial region gets narrower and narrower when sodium is exchanged for transition metal cations (Ni ~ § Cu2+: Fig. 1 and [33]; Co 2+ and Zn 2+ [32]. It vanishes when the exchange level reaches ca.…”