Comparison of amine-impregnated mesoporous carbon with microporous activated carbon and 13X zeolite for biogas purification

Abstract

CH 4 . Depending on the process used during production, along with the type of fermented material, the composition of the produced gas can vary significantly. However, from an anaerobic digester, a significant portion of the produced gas will always be CO 2 . In order to enhance the gas stream for energy production processes, an adsorption process can be used to purify the individual components [1]. Purification of the gas mixtures to produce two high purity gas streams has the added benefit of producing a higher value product of close to pure methane along with a CO 2 stream that could potentially be sequestered, preventing the release of CO 2 into the atmosphere and hence reducing the environmental impact of the process. This is referred to as biogas upgrading and, as a result of its green power generation credentials, the optimisation of the upgrading process has recently begun to attract interest as an area of research [1][2][3]. The optimal technology for biogas upgrading is highly dependent on the specific biogas process/plant. The biogas feedstock, the scale of the plant and the acceptable concentration of impurities in the product streams are all important factors in selecting an upgrading technology. A variety of technologies have been investigated and, in certain cases, implemented such as water scrubbing and pressure swing adsorption (PSA) [4], cryogenic separation, chemical absorption, physical absorption and membrane separation [5,6]. A review comparing the cost and investigating the appropriate utilisation of the various approaches was recently published by Sun et al. [7]. From this review it is clear that further work is required to establish the potential of the different technologies if biogas upgrading is to find more widespread application. There are also several recent reports that propose systems to lower the cost of gas separation. In 2015 Kim et al. [8] proposed a four column PSA process using a carbon molecular sieve as adsorbent that only had a selectivity for CO 2 over CH 4 of 1.9. Grande Abstract Three materials are directly compared for their potential for biogas purification: 13X zeolite, microporous activated carbon and mesoporous activated carbon impregnated with polyethyleneimine. The amine-impregnated material shows the highest selectivity for CO 2 over CH 4 but this should be balanced by the higher operating temperature required. All three materials could be used for biogas purification with the advantages and diasadvantages clearly presented.

Understanding the Effect of Water on CO2 Adsorption

“…As mentioned earlier, the most common methods for the preparation of supported amine adsorbents are (i) impregnation of amines on porous materials such as silica, 1 0 7 , 1 1 2 − 1 1 4 , 1 1 7 , 1 9 7 , 2 0 1 , 2 1 3 , 4 4 4 , 4 4 5 alumina, 4 4 6 activated carbon, 121,447,448 MOFs, 127 zeolites, 448,449 and clays, 450 and (ii) surface grafting of amine-containing species mostly on silica, 76,129,136−138 but occasionally on alumina 451 and other supports. 452 Other procedures such as amine tethering 144,145,148−153,205,408−416 and ligand modification [154][155][156]453 have also been used, particularly for MOFs.…”

Diffusion kinetics of CO2 in amine‐impregnated MIL‐101, alumina, and silica adsorbents

“…To our knowledge, this is the only instance of the ZLC technique used to characterize the sorption kinetics of amino‐adsorbents. More recently, Brandani and coworkers utilized the ZLC method to measure irreversibly adsorbed CO 2 on the surface of amine‐grafted silicas and amine‐impregnated mesoporous carbons. The authors demonstrated that ZLC desorption curves can provide results comparable to calorimetric techniques for determining CO 2 uptakes.…”

Grass-Like Structured Mesoporous Carbon as an Acid Red 119 Dye Adsorbent

“…Carbon-based materials demonstrate widespread applications in industrial fields due to their wide variety of structures that permit the development of several materials for different applications [1]. Due to its characteristics of a high surface area and a pore diameter of less than 2 nm, activated carbon (AC) has widely been applied in adsorption [2], catalysis [3], purification [4], and separation [5], as well as a capacitor electrode [6]. However, uniformity with respect to the pore size, shape, and volume is crucial as these factors limit the separation ability of carbon materials for different-sized molecules [7].…”

“…Hence, advances in mesoporous carbon materials [8] have led to the discovery of mesoporous carbon by the hard- [9] and soft- [5] template methods. Due to its excellent properties of electrical conductivity, inertness, thermal stability, high surface area, and superior pore structure, mesoporous carbon has been extensively used in industrial applications, such as energy storage [10], gas separation [4], CO 2 capture [11], and air and water purification [12][13][14][15]. Moreover, it is possible to control the pore size, volume, and surface area via the modification of synthetic methods.…”