Calorimétrie d'adsorption de CO2 et C2H4 sur des zéolites A échangées par Co2+ et Zn2+

Amari, Djilali; Ginoux, J. L.; Bonnetain, L.

doi:10.1051/jcp/1990871083

Cited by 6 publications

(11 citation statements)

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“…5) for low exchange levels, a result which supports our hypothesis, and then rises again and stabilizes around 0.15 molecule-cav -1 ( Fig. 5 at 353 K; the same values are found at 293 K [1]). Thus we may view that about one half of the Na I chemisorption sites is ultimately replaced by Li I chemisorption sites.…”

Section: Adsorption Of C02supporting

confidence: 86%

“…As previously found [1], the molar heats of adsorption vs. the adsorbed amount exhibits an abruptly falling part, followed by a plateau stretching from less than 0.4 to more than 4 moleeule, cav -1 ( Figs 1-4). The measurements were made at 293 K and 353 K. The results depend only slightly on the temperature ( For the case of the original or recationized NaA, and LiNaA (Figs 1-2), the initial heats are high (120 to 80 kJ'mo1-1 for NaA, more than 100 kJ "mo1-1 for most of the LiNaA samples), and the plateau is significantly lower (33 to 45 kJ.…”

Section: Adsorption Of C02supporting

confidence: 79%

“…Unlike these authors, we have suggested this peculiar Na + is in site I (axis of the six-oxygen ring) [1]. Li + is known to replace Na + preferentially in sites I [8][9][10]; as high initial heats are maintained after the introduction of Li +, our hypothesis seems to be no longer valid.…”

Section: Adsorption Of C02contrasting

confidence: 69%

“…The cation exchange was performed with aqueous solutions of cation chloride as earlier described; the original zeolite was also partly recationized up to 11.4 +0.5 Na + per a cage using a NaC1 solution [1]. Each sample will be named Mx after the exchanging metal M and the percentage x of Na + exchanged (Li64, Ni6, Cu13...).…”

Section: Experimental Partmentioning

confidence: 99%

“…In a previous paper [1], we have measured the heat of adsorption of CO2 and C2H4 on a series' of partly exchanged zeolites NaMA, where M = Co 2+ or Zn 2+. We evidenced the outstanding influence of the cation nature and of the exchange level: CO2 is strongly adsorbed on a little number of peculiar sites of NaA (less than 0.3 per a cage), that are removed by cation exchange.…”

Section: Introductionmentioning

confidence: 99%

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

Amari

Ginoux

Bonnetain

1991

Journal of Thermal Analysis

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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.

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Section: Adsorption Of C02supporting

confidence: 86%

Section: Adsorption Of C02supporting

confidence: 79%

Section: Adsorption Of C02contrasting

confidence: 69%

Section: Experimental Partmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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

Amari

Ginoux

Bonnetain

1991

Journal of Thermal Analysis

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

Amari

Cuesta

Nguyen

et al. 1992

Journal of Thermal Analysis

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Calorimetric measurements of the heat of adsorption of CO2 on zeolites with variable content of mono-and divalent cations lead to common conclusions. High initial heats (up to 120 kJ-md -1 for NaA), generally associated with a slow and activated rate of adsorption, are found for high contents of Na +, Li+ or Ca 2 § They are attributed to a limited number of chemisorption sites (0.3 per cr cage in NaA).Physisorption results in lower heats (25-50 kJ.mol-1). The lowest values are obtained with partially or totally decationized zeolites. Transition metal cations induce frequently weaker interactions than IA or IIA. Finally the stronger the energy of adsorption is, the larger the adsorbed amount is.

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