Post-combustion CO2 capture from the flue gas is one of the key technology options to reduce greenhouse gases, because this can be potentially retrofitted to the existing fleet of coal-fired power stations. Adsorption processes using solid sorbents capable of capturing CO2 from flue gas streams have shown many potential advantages, compared to other conventional CO2 capture using aqueous amine solvents. In view of this, in the past few years, several research groups have been involved in the development of new solid sorbents for CO2 capture from flue gas with superior performance and desired economics. A variety of promising sorbents such as activated carbonaceous materials, microporous/mesoporous silica or zeolites, carbonates, and polymeric resins loaded with or without nitrogen functionality for the removal of CO2 from the flue gas streams have been reviewed. Different methods of impregnating functional groups, including grafting techniques and modifying the support materials, have been discussed to en...

Post-Combustion CO2 Capture Using Solid Sorbents: A Review

Adsorbents for the post-combustion capture of CO2 using rapid temperature swing or vacuum swing adsorption

CO2 absorption and regeneration of alkali metal-based solid sorbents

https://www.tandfonline.com/doi/pdf/10.1088/1468-6996/9/1/013007

Advances in principal factors influencing carbon dioxide adsorption on zeolites

Biogas is an increasingly attractive renewable resource, envisioned to secure future energy demands and help curb global climate change. To capitalize on this resource, membrane processes and state-of-the-art membranes must efficiently recover methane (CH4) from biogas by separating carbon dioxide (CO2). Composite (a.k.a. mixed-matrix) membranes, prepared from common polymers and rationally selected/engineered fillers, are highly promising for this application. This review comprehensively examines filler materials that are capable of enhancing the CO2/CH4 separation performance of polymeric membranes. Specifically, we highlight novel synthetic strategies for engineering filler materials to develop high-performance composite membranes. Besides, as the matrix components (polymers) of composite membranes largely dictate the overall gas separation performances, we introduce a new empirical metric, the "Filler Enhancement Index" ( Findex), to aid researchers in assessing the effectiveness of the fillers from a big data perspective. The Findex systematically decouples the effect of polymer matrices and critically evaluates both conventional and emerging fillers to map out a future direction for next-generation (bio)gas separation membranes. Beyond biogas separation, this review is of relevance to a broader community with interests in composite membranes for other gas separation processes, as well as water treatment applications.

Harnessing Filler Materials for Enhancing Biogas Separation Membranes

The adsorption of CO 2 , at intervals of 30 K from 303 K was carried out on M n + X zeolites (M n + =Ni 2+ or Cr 3+ ) exchanged at different degrees. The structural regularity of the zeolite lattice of NaX and the existence of well-defined cavities within which the adsorbate molecules are lodged suggest that it should be possible to use various isotherm equations. Several models were thus used to describe the experimental isotherms. The best fit of adsorption isotherm data is obtained with the Sips model. The Volmer model also describes satisfactorily the isotherms of CO 2 adsorption by NaX, Ni( x )X, and Cr( x )X. Analysis of the isosteric heat reveals a character energetically heterogeneous for NaX and Ni( x )X samples exchanged at a higher degree of Ni 2+ exchange and at low coverage. Specific interaction is also obtained between the adsorbate molecules and Cr( x )X exchanged at a lower degree. From these considerations, hypotheses will be advanced to describe the behavior of the adsorbed phase within zeolitic cavities.

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

Sorption of carbon dioxide by zeolite X exchanged with Zn2+ + and Cu2+

The crystallization of the zeolite HS was studied during the synthesis of the zeolite 4A using several raw materials like diatomite, kaolin and bentonite. First, these three materials were activated mainly by melting in the presence of caustic soda. The comparison with the pure reagents (solution of sodium silicate and sodium aluminate) as a reference allowed to deduce that an appearance of the zeolite HS during the synthesis is observed with most of the raw materials. Its formation takes place when the concentration of aluminium decreases below the value corresponding to the pure products in the liquid phase. This situation takes place when the reactant gel is heterogeneous, which is characteristic of all the raw materials studied. This seems to be the reason for the formation of zeolite HS.

Etude de la synthese des zeolites 4A et HS a partir de produits naturels

Adsorption of C 3 H 6 has been carried out thermogravimetrically on M 2+ X zeolites (M 2+ =Zn 2+ or Cu 2+ ) exchanged at different degrees. The Gibbs energy change, the isosteric heat and the differential entropy change of C 3 H 6 adsorbed at intervals of 20 K between 303 and 363 K are investigated. Analysis of the Gibbs energy change curves reveals particularly the character energetically heterogeneous of NaX and Zn( x )X samples with respect to the C 3 H 6 adsorption. Evaluation of the isosteric heat shows that these adsorbents present strong adsorptive centre–adsorbate interactions, in contrast to Cu( x )X where it is noted the predominance of attractive adsorbate–adsorbate interactions. Examination of differential entropy change shows that for NaX and Zn(23)X zeolites, the adsorbed phase is in a state strongly localized, at least at low concentrations of zeolitic propene, whereas the adsorbed molecules, in the case of Zn(62)X, have a restricted 2D translational motion, throughout the entire coverage range. For Cu( x )X samples, the mobility of the adsorbed phase decreases with increasing adsorbate loading.

Adsorption of propene on NaX zeolite exchanged with Zn2+ and Cu2+

Adsorption of carbon dioxide by X zeolites exchanged with bivalent cations. The adsorption of carbon dioxide by X zeolites exchanged by Mg 2+ , Sr 2+ , Zn 2+ and Cu 2+ cations was studied by thermogravimetry. The corresponding isosteric heats of adsorption decrease with the filling of pore volume, except for Cu(63)X. This evolution of the heat indicates a specific interaction between cations present within supercages and CO 2 molecules. Several models have been used in order to describe the experimental isotherms. The best fit of sorption isotherm data was obtained with the Sips model.

Zoubir Derriche

Papers

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

Sorption of carbon dioxide by zeolite X exchanged with Zn2+ + and Cu2+

Etude de la synthese des zeolites 4A et HS a partir de produits naturels

Adsorption of propene on NaX zeolite exchanged with Zn2+ and Cu2+

Adsorption de CO2 par des zeolithes X echangees par des cations bivalents