## 1 Introduction  
The concentration of carbon dioxide (CO\({}_{2}\)) in the atmosphere has increased significantly from about 280 ppm in 1750 (pre-industrial era) to 367 ppm in 1999 [1] and has recently reached the value of 408 ppm [2]. Consequently, global temperature has increased (17 of the 18 warmest years on record have occurred since 2001), the 40% arctic extent has decreased from 1980, and global average sea level has risen almost 2 centimeters over the past 100 years [2]. Industry accounts for one-third of all the energy used globally, for almost 40% of worldwide CO\({}_{2}\) emissions, and around 30% of CO\({}_{2}\) released to the atmosphere comes from fossil fuel power plants [3]. However, although CO\({}_{2}\) capture is a global issue, there is no simple solution that can be applied on a global scale. The most extended capture method is absorption using amines (e.g., monoethylamine or MEA). Nevertheless, there are still some gaps in this technology. Apart from the solvent loss during the process [4] and the large amount of heat that is required to regenerate the solvent [5], critical operating limitations exist, such as emulsions, foaming or flooding [6], and amines, which are very toxic compounds. In addition, the current technology is destined to CO\({}_{2}\) sequestration for further transport by pipeline or ship and injection into a storage site, normally an underground geological formation or the ocean. Alternative technologies are thus a key issue in the development of processes for CO\({}_{2}\) capture and/or reutilization, such as absorption using novel solvents (e.g., ionic liquids), calcium looping, adsorption, and membrane technology [7]. Ionic liquids (organic salts with a melting point below 100 \({}^{\circ}\)C) have negligible vapor pressure and are considered in separation and reaction, but their high viscosity and price in comparison with conventional absorbers do not show any advantages from an economic point of view [8; 9]. Calcium looping technology is based on the reaction of CO\({}_{2}\) and calcium oxide (CaO) to obtain calcium carbonate, which is calcined to produce pure CO\({}_{2}\) for sequestration [10]. Although the low price, abundant natural source of CaO and the possibilities of an integrated system power plant-cement plant-CO\({}_{2}\) capture [11], this technology has several challenges: the fast decay in CO\({}_{2}\) carrying capacity (i.e., the level of conversion) over long cycles, the sorbent reactivity decay due to competing reactions, ash fouling or loss of materials, and its reactivation with thermal or chemical treatments [7]. In CO\({}_{2}\) adsorption, the gas diffuses into adsorbent pores of a solid that should have high adsorption capacity and selectivity for CO\({}_{2}\), chemical stability to impurities, low cost, etc. [12; 13]. Activated carbon and zeolite-based sorbents are the most common adsorbents because of the low regeneration energy, cheap cost, and fast adsorption kinetics, but they are strongly influenced by temperature, pressure, and the presence of moisture [7]. Metal organic frameworks have more adsorption capacity than zeolites and the water adsorption affect less but the study of higher selectivities and capacities must occur [14]. Regarding membrane technology, research focused on CO\({}_{2}\) capture started around 1990 and since then, great advances have occurred: higher mass transfer coefficients, new materials for membrane synthesis, integration of membrane-based technology, etc. Nowadays, there are two main approaches for CO\({}_{2}\) capture with membranes [15]. First, membranes can be used as selective barriers that determine which compound permeates faster. Gas permeation (the membrane has a dense structure) and supported liquid membranes (there is liquid inside the membrane pores that is responsible for the separation) are the most common technologies applied in this sense [7]. Here, permeability and selectivity are the principal properties.