The Infrared Spectra of Carbon Dioxide Adsorbed on Zeolite X

Ward, John W.; Habgood, H. W.

doi:10.1021/j100876a034

Cited by 107 publications

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“…With respect to ν asym , it is unusual for a frequency to increase upon protonation. However, the increase is small and it closely follows the 5-24 cm -1 increases in ν asym observed when CO 2 coordinates to various divalent metal ions in zeolites [45] and in gas phase protonation of CO 2 . [43] In point of fact, ν asym of free CO 2 is quite insensitive to protonation as either HCO 2 + or H(CO 2 ) 2 + , reflecting both the weak basicity of CO 2 and its large HOMO-LUMO gap.…”

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confidence: 65%

The Strongest Acid: Protonation of Carbon Dioxide

2015

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The strongest carborane acid, H(CHB11F11), protonates CO2 while traditional mixed Lewis/Brønsted superacids do not. The product is deduced from IR spectroscopy and calculation to be the proton disolvate, H(CO2)2+. The carborane acid H(CHB11F11) is therefore the strongest known acid. The failure of traditional mixed superacids to protonate weak bases such as CO2 can be traced to a competition between the proton and the Lewis acid for the added base. The high protic acidity promised by large absolute values of the Hammett acidity function (H0) is not realized in practice because the basicity of an added base is suppressed by Lewis acid/base adduct formation.

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confidence: 65%

The Strongest Acid: Protonation of Carbon Dioxide

2015

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“…An early infrared (IR) spectroscopy study of CO 2 adsorption on the zeolites X and Y (FAU) revealed physisorption to be the dominant process in CO 2 adsorption on these zeolites, although a very small fraction of the adsorbed CO 2 (up to 0.15 mmol g À1 ) was chemisorbed in the form of either a carbonate or carboxylate. [31][32][33] The physisorption was influenced by the electric field created by the chargebalancing cations in the pores and by hydrogen bonding with surface silanol groups. [31][32][33] In this sense, it has been shown that the CO 2 adsorption properties of zeolites are affected by the aluminum content that defines the number of charge-balancing cations in the structure as well as the type of these moieties.…”

Section: Inorganic Adsorbentsmentioning

confidence: 99%

“…[31][32][33] The physisorption was influenced by the electric field created by the chargebalancing cations in the pores and by hydrogen bonding with surface silanol groups. [31][32][33] In this sense, it has been shown that the CO 2 adsorption properties of zeolites are affected by the aluminum content that defines the number of charge-balancing cations in the structure as well as the type of these moieties. From studies on the basic site strength of various zeolites including zeolites X, Y, L (LTL), mordenite (MOR), and ZSM-5 (MFI), Barthomeuf suggested that the base strength of zeolites increased along with an increase of the aluminum content because of the lower electronegativity of aluminum compared to that of silicon.…”

Section: Inorganic Adsorbentsmentioning

confidence: 99%

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Adsorbent Materials for Carbon Dioxide Capture from Large Anthropogenic Point Sources

2009

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Since the time of the industrial revolution, the atmospheric CO(2) concentration has risen by nearly 35 % to its current level of 383 ppm. The increased carbon dioxide concentration in the atmosphere has been suggested to be a leading contributor to global climate change. To slow the increase, reductions in anthropogenic CO(2) emissions are necessary. Large emission point sources, such as fossil-fuel-based power generation facilities, are the first targets for these reductions. A benchmark, mature technology for the separation of dilute CO(2) from gas streams is via absorption with aqueous amines. However, the use of solid adsorbents is now being widely considered as an alternative, potentially less-energy-intensive separation technology. This Review describes the CO(2) adsorption behavior of several different classes of solid carbon dioxide adsorbents, including zeolites, activated carbons, calcium oxides, hydrotalcites, organic-inorganic hybrids, and metal-organic frameworks. These adsorbents are evaluated in terms of their equilibrium CO(2) capacities as well as other important parameters such as adsorption-desorption kinetics, operating windows, stability, and regenerability. The scope of currently available CO(2) adsorbents and their critical properties that will ultimately affect their incorporation into large-scale separation processes is presented.

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“…In the case of several cationic zeolites, the chemical adsorption of CO 2 is accompanied by the formation of carbonates including very stable monodentate or unidentate carbonates and bidentate carbonates, at their surface, due to the interaction of CO 2 with the oxygen bridging aluminum and silicon atoms [24,35,[58][59][60][61][62]. Gallei and Stumpf [58] have described the formation of monodentate carbonate at the surface of zeolite CaY by a reaction involving three steps.…”

Section: Influence Of the Carbonates Formation On The C O 2 Adsorptionmentioning

confidence: 99%

Advances in principal factors influencing carbon dioxide adsorption on zeolites

Bonenfant

Kharoune

Niquette

et al. 2008

Science and Technology of Advanced Materials

273

179

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We report the advances in the principal structural and experimental factors that might influence the carbon dioxide (CO 2 ) adsorption on natural and synthetic zeolites. The CO 2 adsorption is principally govern by the inclusion of exchangeable cations (countercations) within the cavities of zeolites, which induce basicity and an electric field, two key parameters for CO 2 adsorption. More specifically, these two parameters vary with diverse factors including the nature, distribution and number of exchangeable cations. The structure of framework also determines CO 2 adsorption on zeolites by influencing the basicity and electric field in their cavities. In fact, the basicity and electric field usually vary inversely with the Si/Al ratio. Furthermore, the CO 2 adsorption might be limited by the size of pores within zeolites and by the carbonates formation during the CO 2 chemisorption. The polarity of molecules adsorbed on zeolites represents a very important factor that influences their interaction with the electric field. The adsorbates that have the most great quadrupole moment such as the CO 2 , might interact strongly with the electric field of zeolites and this favors their adsorption. The pressure, temperature and presence of water seem to be the most important experimental conditions that influence the adsorption of CO 2 . The CO 2 adsorption increases with the gas phase pressure and decreases with the rise of temperature. The presence of water significantly decreases adsorption capacity of cationic zeolites by decreasing strength and heterogeneity of the electric field and by favoring the formation of bicarbonates. The optimization of the zeolites structural characteristics and the experimental conditions might enhance substantially their CO 2 adsorption capacity and thereby might give rise to the excellent adsorbents that may be used to capturing the industrial emissions of CO 2 .

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The Infrared Spectra of Carbon Dioxide Adsorbed on Zeolite X

Cited by 107 publications

References 0 publications

The Strongest Acid: Protonation of Carbon Dioxide

The Strongest Acid: Protonation of Carbon Dioxide

Adsorbent Materials for Carbon Dioxide Capture from Large Anthropogenic Point Sources

Advances in principal factors influencing carbon dioxide adsorption on zeolites

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