Adsorbent

Abstract

A solid adsorbent for a carbon dioxide recovery process, the adsorbent comprising a solid adsorbent support containing pores and a secondary amine covalently bonded to the solid adsorbent support, the secondary amine being confined inside the pores of the solid adsorbent support and present at a density exceeding 4 amine groups / nm 2 A solid adsorbent is disclosed herein. Also disclosed herein are a method for preparing the solid adsorbent of the present invention, a method for the regeneration of the solid adsorbent of the present invention, the use of the solid adsorbent in the adsorption of carbon dioxide, and the use of the solid adsorbent in a carbon dioxide recovery process using temperature swing adsorption with carbon dioxide purge as a desorption strategy.

Description

Technical Field

[0001] The present disclosure relates to an adsorbent for a carbon dioxide recovery process.

Background Art

[0002] There are many environmental protection pressures to reduce the emission of carbon dioxide gas into the atmosphere. A known technique for significantly reducing the carbon dioxide released into the atmosphere is carbon capture and storage CCS. CCS includes an adsorbent that recovers at least a portion, preferably substantially all, of the carbon dioxide content of the gas mixture. If the gas mixture is ultimately released into the atmosphere, its carbon dioxide content is reduced by the carbon dioxide recovery process. The adsorbent may be produced by a process that releases carbon dioxide in the contained environment. The regenerated adsorbent may then be reused in the carbon dioxide recovery process from the gas mixture. CCS is described in more detail below.

[0003] Assuming that carbon-based fuels will continue to be a major source of energy in the future, CCS has been investigated as a feasible way to reduce anthropogenic CO2 emissions [Reference: 1]. Due to the potential for cost-effective improvements in existing power plants, post-combustion CO2 capture technology has been widely investigated compared to pre-combustion and oxy-fuel combustion CO2 capture systems [Reference: 2]. Among existing CO2 separation methods, such as cryogenic technology, membranes, adsorption, and absorption, the latter has received the most attention [References: 3, 4]. It is based on aqueous alkanolamine solutions and has been the most studied and industrially implemented post-combustion CO2 separation approach in the last 50 years [References: 5, 6]. Despite long-term evaluations, the amine scrubbing process remains an expensive technology. The energy penalty associated with this process mainly stems from the energy required to heat the total 30% amine (e.g., monoethanolamine (MEA)) in the aqueous solution and the high energy to break the carbamate / carbonate species to release CO2, with approximately 150 - 180 kJ / mol typically required. Most of the total energy is dissipated during the heating and evaporation of water [Reference: 7]. Furthermore, since this technology has several other problems, such as amine loss, equipment corrosion, and secondary pollution (e.g., acids, ammonia) [Reference: 7], the search for alternatives has been promoted. Solid adsorbents, such as zeolites, carbons, metal-organic frameworks (MOFs), etc., functionalized with amines on mesoporous materials have been widely studied to prevent the difficulties shown above. However, solid adsorbents cannot meet the requirements for CO2 capture, i.e., high CO2 adsorption capacity, fast reaction rate, high CO2 selectivity, mild regeneration conditions, long-term thermochemical stability, moisture resistance, and low cost [Reference: 8]. Due to the large CO2 capacity and high CO2 selectivity at very low CO2 concentrations (<5%), amine-based adsorbents are a good choice for post-combustion gas treatment of natural gas [Reference: 8]. There are three methods for loading amines onto carriers: impregnation, grafting, and in-situ polymerization.The first class is amine-containing polymer systems such as polyethyleneimine (PEI) [References: 9 - 11], pentaethylenehexamine (PEHA) [References: 12, 13], and tetraethylenepentamine (TEPA) [References: 14 - 16]. Due to their high amine density, they can easily reach a CO2 capacity of over 2 mmol / g. However, the polymers are physically deposited on the carrier, and thus, leaching becomes a problem at high regeneration temperatures. Furthermore, the formation of urea in the presence of oxygen and the high concentration of CO2 during regeneration at high temperatures cause corrosion and reduce the lifespan of the adsorbent [References: 10, 16]. An effective approach to prevent this is to fix the amine structure on the carrier surface by chemical bonding (i.e., by covalent bonding) called grafting [References: 17 - 20] and in-situ polymerization of the amine class of confined monomers [References: 21, 22]. Nevertheless, both classes are based on several synthetic steps and thus become more complex and result in a higher overall cost [Reference: 23]. Since a lot of effort has been spent on modifying the polymer structure to improve thermochemical stability and optimize the heat of adsorption before impregnation, the evaluation of the number of synthetic steps of the amine solid adsorbent class at this stage is relative [References: 24 - 27]. Typically, the structural adjustment functions worse in terms of CO2 uptake compared to their prototypes due to a decrease in amine density and an increase in the tertiary amine fraction [Reference: 24], and thus approaches the CO2 capacity provided by grafted adsorbents [Reference: 18]. Belmabkhout et al. [Reference: 28] demonstrated the high CO2 selectivity of the TRI-PE-MCM-41 adsorbent by studying CO2 adsorption in mixtures of CH4, N2, H2, and CFAir (N2:O2 = 80:20) at 25 °C up to 1 bar, showing that the adsorption of other gases is negligible. Since natural gas-based flue gases occur with a high water concentration (7 - 10%) [Reference: 29], it is essential to evaluate the effect of moisture. Water is widely recognized to boost CO2 uptake by forming bicarbonates in addition to carbamates. However, due to amine-H2O hydrogen bonding, water adsorbs at low adsorption temperatures and then consumes some of the energy in the subsequent regeneration step.Grafted amines are another interesting class of solid adsorbents. Grafted secondary amines have been shown to have excellent thermochemical stability. However, their relatively low CO2 adsorption capacity is a drawback.

[0004] Regarding the regeneration strategy, most of the explorations in this area have been almost entirely focused on the generation of adsorbents with the maximum adsorption capacity, leaving aside the aspect of regeneration. So far, the desorption stage has been carried out using (i) temperature swing adsorption (TSA) with an inert purge gas such as N2 or He (TSA / Inert), followed by H2O with condensation (TSA / H2O), or CO2 (TSA / CO2), (ii) pressure swing adsorption (PSA) almost alone as vacuum swing adsorption (VSA) or in combination with TSA [References: 8, 31]. The essential part of the previous explorations was to regenerate the adsorbent using TSA / Inert [References: 9, 12, 13, 16, 17, 21, 32 - 35], which basically depends on the supply of sufficient energy assisted by the driving force of concentration to reverse the exothermic reaction. This helps to evaluate the thermal stability of the adsorbent, but it means that it does not concentrate CO2 for subsequent compression and transportation to storage sites and more explorations are needed to establish a feasible separation process. The use of TSA / H2O requires evaporation and condensation of water between each cycle, causing an increase in heat consumption. For amine solvents, it has been found that CO2 desorption using steam releases some of the amine and requires concentration adjustment with fresh amine, causing additional costs [Reference: 7]. Since water affects the polymer viscosity, a similar relationship can be applied to low molecular weight amine-based polymers physically deposited on a solid support. Different from TSA / H2O, TSA / CO2 can directly generate a CO2-enriched stream ready for storage by using CO2 as a sweep gas. Thermodynamically, this is achievable at temperatures higher than 120°C depending on the amine-containing compound structure. However, the thermal stability of physically impregnated polymers will be significantly impaired under these conditions. Furthermore, the amine groups will undergo an irreversible reaction with CO2 resulting in the formation of urea species [References: 24, 26, 36]. Some studies have used epoxy compounds to partially convert primary amines, which are prone to deactivation and stabilize the amine structure [References: 24, 26]. Despite the achieved stability, CO2 uptake at low CO2 partial pressures decreased significantly with the increase in molecular weight and tertiary amines.

[0005] When an amine-containing polymer is to be used, VSA is a gentle approach as it preserves the CO2 capacity and thermochemical stability of the adsorbent [Reference: 25] and does not require further CO2 concentration downstream. However, by using only vacuum, the desorption time increases significantly, and thus most studies show a combination of VSA / TSA [Reference: 31]. According to Bollini et al. [Reference: 31], the cost of the vacuum equipment and the process itself can be too high. Furthermore, TSA / H2O and TSA / CO2 technologies become more attractive due to the availability of waste heat in power plants [References: 24, 26].

[0006] There is a general need to improve adsorbents for CCS systems.

Summary of the Invention

[0007] The present invention provides a solid adsorbent for a carbon dioxide recovery process, wherein the adsorbent comprises a solid adsorbent carrier containing pores, and a secondary amine covalently bonded to the solid adsorbent carrier, the secondary amine being confined inside the pores of the solid adsorbent carrier and present at a density exceeding 4 amine groups / nm 2 to provide a solid adsorbent.

[0008] The present invention further provides a method for preparing a solid adsorbent for a carbon dioxide recovery process, wherein the adsorbent comprises a solid adsorbent carrier containing pores, and a secondary amine covalently bonded to the solid adsorbent carrier and confined inside the pores of the solid adsorbent carrier, and the method comprises contacting the solid adsorbent carrier containing pores with (a) a compound containing a secondary amine group and a group capable of forming a covalent bond with the solid adsorbent carrier, and (b) water, wherein the compound is present in an amount of 2 - 6 mL of the compound per gram of the solid adsorbent carrier, Water is present in an amount of 0.5 to 1.5 mL of water per gram of the solid adsorbent carrier, providing a method.

[0009] The present invention further provides a solid adsorbent for a carbon dioxide recovery process, wherein the adsorbent comprises a solid adsorbent carrier having pores, and a secondary amine covalently bonded to the solid adsorbent carrier and confined inside the pores of the solid adsorbent carrier, wherein the solid adsorbent is obtainable by the above method of the present invention, providing a solid adsorbent.

[0010] The present invention further provides a method for regenerating a solid adsorbent for a carbon dioxide recovery process, wherein the solid adsorbent containing carbon dioxide is heated at a temperature of 120 to 150 °C, preferably at a temperature of 130 to 145 °C, to release the contained carbon dioxide, wherein the solid adsorbent is the solid adsorbent according to the present invention, providing a method.

[0011] The present invention further provides the use of a solid adsorbent in the adsorption of carbon dioxide, wherein the adsorption of carbon dioxide is carried out at a temperature below 100 °C, wherein the solid adsorbent is the solid adsorbent according to the present invention, providing a use.

[0012] The present invention further provides the use of a solid adsorbent in a carbon dioxide recovery process using temperature swing adsorption with carbon dioxide purge as a desorption strategy, wherein the solid adsorbent is the solid adsorbent according to the present invention, providing a use.

[0013] To avoid misunderstanding, all references to "secondary amine" or "secondary amines" in this specification are equally considered to relate to the multiplicity of the type of secondary amine as necessary (i.e., one or more covalently bonded secondary amines, and one or more secondary amines are confined inside the pores of the solid adsorbent carrier and are present at a density exceeding 4 amine groups / nm 2 ).

[0014] Any aspect of the present invention is described in the dependent claims and in the sections of the following detailed description.

Brief Description of the Drawings

[0015]

Figure 1a1b

Figure 1c1d

Figure 2a2b

Figure 3

Figure 4a4b4c

Figure 5a5b

Figure 5c

Figure 6

Figure 7

Figure 8a8b

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

DETAILED DESCRIPTION OF THE INVENTION

[0016] Embodiments of the present invention provide an improved adsorbent for CCS systems.

[0017] Embodiments provide a high surface amine density solid adsorbent for CO2 capture with low energy regeneration.

[0018] The characteristics of the CO2 recovery adsorbent according to the embodiment may include high CO2 adsorption capacity, long-term chemical stability under adsorption and desorption conditions, fast reaction rate, low regeneration heat, mild desorption conditions, high CO2 selectivity, and low cost (material preparation). In an embodiment, the adsorbent may have some or all of these characteristics.

[0019] In particular, in an embodiment, the adsorbent comprises the following. - A relatively high CO2 adsorption capacity of about 2 mmol / g 吸着剤 - High long-term thermochemical stability under adsorption-desorption conditions - Fast reaction rate - Low heat requirement for the desorption system - High CO2 selectivity

[0020] Particularly advantageous characteristics of the CO2 recovery adsorbent according to the embodiment are (a) stability in the presence of oxygen (e.g., in flue gas), (b) stability in the presence of pure CO2 (even at high temperatures), and (c) regeneration heat that decreases with increasing temperature and reaches zero regeneration heat at 120 - 140 °C.

[0021] The adsorbent according to the embodiment includes a solid adsorbent with grafted secondary amines. The adsorbent may have an increased CO2 capacity compared to known adsorbents. This can reduce the energy penalty and cost of the CO2 recovery process.

[0022] Thus, as described above, the first adsorbent of the present invention is a solid adsorbent for a carbon dioxide recovery process, and the adsorbent is A solid adsorbent carrier containing pores, and A secondary amine covalently bonded to the solid adsorbent carrier, the secondary amine being confined inside the pores of the solid adsorbent carrier and present at a density exceeding 4 amine groups / nm 2 is a solid adsorbent.

[0023] Preferably, the solid adsorbent carrier is silica, fused silica, silica gel, carbon, zeolite, or alumina. More preferably, the solid adsorbent carrier is a silica adsorbent carrier, such as mesoporous silica such as MCM-41 and SBA-15. Even more preferably, the silica adsorbent carrier is MCM-41.

[0024] Even more preferably, the silica adsorbent carrier is a porous foam mesoporous silica adsorbent carrier. A particularly preferred porous foam mesoporous silica adsorbent carrier is porous foam MCM-41 (PE-MCM-41).

[0025] Preferably, the secondary amine covalently bonded to the solid adsorbent carrier has a structure containing one amine group, and the structure is a C2-C 12 (preferably C2-C8) saturated hydrocarbyl structure. More preferably, the secondary amine covalently bonded to the solid adsorbent carrier has the formula (I):

[0026]

Chemical formula

[0027] Preferably, in the structure according to formula (I), n is 2-5. More preferably, n is 2-4. Particularly preferably, n is 3.

[0028] Preferably, in the structure according to formula (I), p is 0-4. More preferably, p is 0-3. Particularly preferably, p is 0 or 3. Most preferably, p is 0.

[0029] Preferably, in the structure represented by formula (I), n is from 2 to 5, and p is from 0 to 3. More preferably, n is from 2 to 4, and p is from 0 to 3. Even more preferably, n is 3, and p is from 0 to 3. Particularly preferably, n is 3, and p is 0 or 3. Most preferably, n is 3, and p is 0.

[0030] Particularly preferably, the secondary amine covalently bonded to the solid adsorbent carrier has a structure represented by formula (I’):

[0031]

Chemical formula

[0032] In the structure represented by formula (I) or formula (I’), the atom covalently bonded to the solid adsorbent carrier may be directly covalently bonded to the solid adsorbent or may be indirectly covalently bonded to the solid adsorbent. The indirect covalent bond may be via a polymer such as a polysiloxane polymer, and the atom forms a part of the polymer backbone (main chain).

[0033] Preferably, the secondary amine covalently bonded to the solid adsorbent carrier is derived from an aminosilane compound.

[0034] Preferably, the secondary amine has a density of less than 6 amine groups / nm 2 less preferably less than 5.8 amine groups / nm 2 more preferably less than 5.7 amine groups / nm 2 even more preferably less than 5.6 amine groups / nm 2 even more preferably less than 5.5 amine groups / nm 2 even more preferably less than 5.4 amine groups / nm 2 less preferably less than 5.3 amine groups / nm 2 and is present at a density.

[0035] Preferably, the secondary amine has a concentration of 4.4 amine groups / nm 2 More than 4.5 amine groups / nm 2 more preferably greater than 4.8 amine groups / nm 2 More preferably still, more than 4.9 amine groups / nm 2 and even more preferably greater than 5.0 amine groups / nm 2 More preferably, greater than 5.1 amine groups / nm 2 More than 5.2 amine groups / nm 2 are present on the surface of the solid support at a density of greater than

[0036] Thus, in one embodiment, the secondary amine has 4 amine groups / nm 2 More than 6 amine groups / nm 2 Suitably, the secondary amines are present on the surface of the solid support at a density of less than 5 amine groups / nm 2 More than 6 amine groups / nm 2 Preferably, the secondary amines are present on the surface of the solid support at a density of less than 4.4 amine groups / nm 2 More than 6 amine groups / nm 2 less than 4.4 amine groups / nm 2 Exceeds 5.8 amine groups / nm 2 less than 4.5 amine groups / nm 2 Exceeds 5.8 amine groups / nm 2 less than 4.9 amine groups / nm 2 Exceeds 5.7 amine groups / nm 2 and even more preferably less than 5.0 amine groups / nm 2 Exceeds 5.7 amine groups / nm 2 less than, even more preferably less than 5.1 amine groups / nm 2 Exceeds 5.7 amine groups / nm 2 less than 5.2 amine groups / nm 2 Exceeds 5.3 amine groups / nm 2 are present on the surface of the solid support at a density of less than 100 nm.

[0037] As used herein, the solid support includes the outer surface of the solid support (i.e., the surface of the solid support that is not within the pores) and the surface of the solid support within the pores. As used herein, the secondary amine covalently bonded to the solid adsorbent support is selectively covalently bonded to the surface of the solid support within the pores, i.e., the secondary amine is confined within the pores of the solid adsorbent support.

[0038] Thus, in an embodiment, the secondary amine is substantially exclusively covalently bonded to the surface of the solid adsorbent support within the pores. In a particularly preferred embodiment, the secondary amine is exclusively covalently bonded to the surface of the solid adsorbent support within the pores, i.e., the secondary amine is not bonded to the outer surface of the solid adsorbent support.

[0039] As used herein, "selectively covalently bonded to the surface of the solid support within the pores" means that the solid adsorbent of the present invention has a ΔV / V ratio of 0.5 to 1.1, preferably 0.7 to 1.1, more preferably 0.8 to 1.1, even more preferably 0.85 to 1.15, still more preferably 0.85 to 1.05, even still more preferably 0.9 to 1.05, and most preferably 0.98 to 1.02. アミノグラフト化 Thus, the secondary amine may be confined within the pores of the solid adsorbent such that the solid adsorbent of the present invention has a ΔV / V ratio of 0.5 to 1.1, preferably 0.7 to 1.1, more preferably 0.8 to 1.1, even more preferably 0.85 to 1.1, still more preferably 0.85 to 1.05, even still more preferably 0.9 to 1.05, and most preferably 0.95 to 1.02. アミノグラフト化 The ratio may be 1. アミノグラフト化 Ideally, the ΔV / V ratio is 1.

[0040] Thus, in an embodiment, the present invention is a solid adsorbent for a carbon dioxide recovery process, the adsorbent comprising a solid silica adsorbent support comprising pores, and a secondary amine covalently bonded to the solid adsorbent support, the secondary amine covalently bonded to the solid adsorbent support having a structure according to formula (I):

[0041] [Chemical formula] (wherein, * represents a bonding point to an atom (preferably Si) that is covalently bonded to or forms a part of the solid adsorbent carrier, n is from 1 to 6, p is from 0 to 5) having, the secondary amine is confined inside the pores of the solid adsorbent carrier and is present at a density exceeding 5 amine groups / nm 2 and less than 6 amine groups / nm 2 to provide a solid adsorbent.

[0042] In another embodiment, the present invention is a solid adsorbent for a carbon dioxide recovery process, wherein the adsorbent is a solid silica adsorbent carrier that is a mesoporous foamed MCM-41, and a secondary amine covalently bonded to the solid adsorbent carrier, and the secondary amine covalently bonded to the solid adsorbent carrier has a structure according to formula (I’):

[0043] [Chemical formula] (wherein, * represents a bonding point to an atom (preferably Si) that is covalently bonded to or forms a part of the solid adsorbent carrier) having, the secondary amine is confined inside the pores of the solid adsorbent carrier and is present at a density exceeding 5 amine groups / nm 2 and less than 6 amine groups / nm 2 to provide a solid adsorbent.

[0044] The embodiment provides a method for preparing such a solid adsorbent by controlling the grafting position, for example, using N-methylaminopropyltrimethoxysilane grafting and polymerization along the high surface area of mesoporous foamed MCM-41. The preparation parameters are a high density of amine groups (e.g., 5.25 amine groups / nm 2Optimized by adjusting the amino silane / SiO2 and H2O / SiO2 ratios for achieving and the internal selective positions relative to the pores, thus resulting in very good adsorption efficiency (such as 0.52 mol CO2 / mol N, etc.) and excellent capacity.

[0045] Thus, as described above, the method of the present invention is a method for preparing a solid adsorbent for a carbon dioxide recovery process, and the adsorbent is a solid adsorbent carrier containing pores, and a secondary amine covalently bonded to the solid adsorbent carrier and confined inside the pores of the solid adsorbent carrier, The method is contacting a solid adsorbent carrier containing pores with (a) a compound containing a secondary amine group and a group capable of forming a covalent bond with the solid adsorbent carrier, and (b) water, and the method wherein the compound is present in an amount of 2 to 6 mL of the compound per gram of the solid adsorbent carrier, and water is present in an amount of 0.5 to 1.5 mL of water per gram of the solid adsorbent carrier.

[0046] Preferably, the solid adsorbent carrier is silica, fused silica, silica gel, carbon, zeolite, alumina. More preferably, the solid adsorbent carrier is a silica adsorbent carrier, such as mesoporous silica such as MCM-41 and SBA-15. Even more preferably, the silica adsorbent carrier is MCM-41.

[0047] Even more preferably, the silica adsorbent carrier is a porous foam mesoporous silica adsorbent carrier. A particularly preferred porous foam mesoporous silica adsorbent carrier is porous foam MCM-41 (PE-MCM-41).

[0048] Preferably, the porous foam MCM-41 is (a) A step of contacting a surfactant (such as hexadecyltrimethylammonium bromide, CTAB, etc.) with a silica network former (such as tetraethyl orthosilicate, TEOS, etc.) and a mineralizing agent (such as ammonia, etc.) in the presence of water. (b) A step of recovering the obtained product, and (c) It can be obtained by a method including a step of calcining the obtained product.

[0049] Preferably, the solid adsorbent carrier for contact has a surface area of about 700 to about 1100 m 2 / g, more preferably about 750 to about 1050 m 2 / g, still more preferably about 800 to about 1000 m 2 / g, even more preferably about 850 to about 950 m 2 / g, most preferably about 890 to about 910 m 2 / g.

[0050] Preferably, the solid adsorbent carrier for contact has a pore volume of about 1.2 to about 2.0 cm 3 / g, more preferably about 1.3 to about 1.9 cm 3 / g, still more preferably about 1.4 to about 1.8 cm 3 / g, even more preferably about 1.5 to about 1.7 cm 3 / g, most preferably about 1.6 to about 1.7 cm 3 / g.

[0051] Preferably, the solid adsorbent carrier for contact has an average pore diameter of about 5 to about 10 nm, more preferably about 6 to about 9 nm, still more preferably about 6.5 to about 8.5 nm, even more preferably about 7 to about 8 nm, and most preferably about 7.3 to about 7.7 nm.

[0052] Preferably, therefore, the solid adsorbent carrier for contact (a) has a surface area of about 700 to about 1100 m 2 / g, and / or (b) has a pore volume of about 1.2 to about 2.0 cm 3 / g, and / or (c) It has an average pore diameter of about 5 to about 10 nm.

[0053] More preferably, the solid adsorbent carrier for contact (a) has a surface area of about 850 to about 950 m 2 / g, and / or (b) has a pore volume of about 1.5 to about 1.7 cm 3 / g, and / or (c) has an average pore diameter of about 7 to about 8 nm.

[0054] Most preferably, the solid adsorbent carrier for contact (a) has a surface area of about 890 to about 910 m 2 / g, and / or (b) has a pore volume of about 1.6 to about 1.7 cm 3 / g, and / or (c) has an average pore diameter of about 7.3 to about 7.7 nm.

[0055] Preferably, the compound contains one amine group.

[0056] Preferably, the compound is an aminosilane. More preferably, the aminosilane contains one amine group. Even more preferably, the aminosilane contains a C2 - C 12 (preferably C2 - C8) saturated hydrocarbyl structure containing one amino group. Particularly preferably, the aminosilane is of formula (II):

[0057]

Chemical formula

[0058] Preferably, X is each independently a halo group or a C1 - C 10It is a leaving group selected from the group consisting of alkoxy groups. Preferably, each X is independently a C1-C6 alkoxy group. Particularly preferably, each X is independently -OCH3 or -OCH2CH3. Most preferably, each X is -OCH3.

[0059] Preferably, in the structure according to formula (II), n is 2-5. More preferably, n is 2-4. Particularly preferably, n is 3.

[0060] Preferably, in the structure according to formula (II), p is 0-4. More preferably, p is 0-3. Particularly preferably, p is 0 or 3. Most preferably, p is 0.

[0061] Preferably, in the structure according to formula (II), n is 2-5 and p is 0-4. More preferably, n is 2-4 and p is 0-3. Even more preferably, n is 3 and p is 0-3. Particularly preferably, n is 3 and p is 0 or 3. Most preferably, n is 3 and p is 0.

[0062] Preferably, in the structure according to formula (II), each X is independently a C1-C6 alkoxy group, n is 2-5, and p is 0-4.

[0063] More preferably, in the structure according to formula (II), each X is independently -OCH3 or -OCH2CH3, n is 2-4, and p is 0-3.

[0064] Therefore, in one embodiment, the aminosilane is N-methylaminopropyltrimethoxysilane or N-butylaminopropyltrimethoxysilane. Most preferably, the aminosilane is N-methylaminopropyltrimethoxysilane.

[0065] Preferably, the water is distilled water.

[0066] Preferably, the contacting step is optionally carried out under reflux in the presence of toluene. Preferably, the toluene is present in an amount of 140 - 417 mL of toluene per gram of the solid adsorbent carrier. More preferably, the toluene is present in an amount of 140 - 300 mL of toluene per gram of the solid adsorbent carrier. Even more preferably, the toluene is present in an amount of 140 - 200 mL of toluene per gram of the solid adsorbent carrier. Still more preferably, the toluene is present in an amount of 140 - 160 mL of toluene per gram of the solid adsorbent carrier. Most preferably, the toluene is present in an amount of about 140 - 300 mL of toluene per gram of the solid adsorbent carrier.

[0067] Preferably, in the contacting, the compound is present in an amount of 2 - 5 mL of the compound per gram of the solid adsorbent carrier. More preferably, the compound is present in an amount of 2.5 - 4.5 mL of the compound per gram of the solid adsorbent carrier. Even more preferably, the compound is present in an amount of 2.5 - 4 mL of the compound per gram of the solid adsorbent carrier. Further preferably, the compound is present in an amount of 2.5 - 3.5 mL of the compound per gram of the solid adsorbent carrier. Most preferably, the compound is present in an amount of 2.8 - 3.2 mL of the compound per gram of the solid adsorbent carrier. Ideally, the compound is present in an amount of about 3 mL of the compound per gram of the solid adsorbent carrier.

[0068] Preferably, in the contacting, the water is present in an amount of 0.55 - 1.5 mL of water per gram of the solid adsorbent carrier. More preferably, the water is present in an amount of 0.6 - 1.5 mL of water per gram of the solid adsorbent carrier. Even more preferably, the water is present in an amount of 0.7 - 1.3 mL of water per gram of the solid adsorbent carrier. Further preferably, the water is present in an amount of 0.7 - 1.2 mL of water per gram of the solid adsorbent carrier. Still further preferably, the water is present in an amount of 0.8 - 1.2 mL of water per gram of the solid adsorbent carrier. Most preferably, the water is present in an amount of 0.9 - 1.2 mL of water per gram of the solid adsorbent carrier. Ideally, the water is present in an amount of 0.9 mL of water per gram of the solid adsorbent carrier.

[0069] Thus, preferably, the compound is present in an amount of 2 to 5 mL of the compound per gram of the solid adsorbent carrier, and water is present in an amount of 0.6 to 1.5 mL of water per gram of the solid adsorbent carrier.

[0070] More preferably, the compound is present in an amount of 2.5 to 4 mL of the compound per gram of the solid adsorbent carrier, and water is present in an amount of 0.7 to 1.2 mL of water per gram of the solid adsorbent carrier.

[0071] Even more preferably, the compound is present in an amount of 2.5 to 3.5 mL of the compound per gram of the solid adsorbent carrier, and water is present in an amount of 0.8 to 1.2 mL of water per gram of the solid adsorbent carrier.

[0072] Still more preferably, the compound is present in an amount of 2.5 to 3.5 mL of the compound per gram of the solid adsorbent carrier, and water is present in an amount of 0.9 to 1.2 mL of water per gram of the solid adsorbent carrier.

[0073] Even still more preferably, the compound is present in an amount of 2.5 to 3.5 mL of the compound per gram of the solid adsorbent carrier, and water is present in an amount of 0.9 mL of water per gram of the solid adsorbent carrier.

[0074] Preferably, the compound is present in an amount of 3 mL of the compound per gram of the solid adsorbent carrier, and water is present in an amount of 0.7 to 1.3 mL of water per gram of the solid adsorbent carrier.

[0075] More preferably, the compound is present in an amount of 3 mL of the compound per gram of the solid adsorbent carrier, and water is present in an amount of 0.7 to 1.2 mL of water per gram of the solid adsorbent carrier.

[0076] Even still more preferably, the compound is present in an amount of 3 mL of the compound per gram of the solid adsorbent carrier, and water is present in an amount of 0.9 to 1.2 mL of water per gram of the solid adsorbent carrier.

[0077] Alternatively, preferably, The compound is present in an amount of 2.0 to 2.4 mL of the compound per gram of the solid adsorbent carrier, and water is present in an amount of 0.6 to 0.9 mL of water per gram of the solid adsorbent carrier, or The compound is present in an amount of 2.5 to 5 mL of the compound per gram of the solid adsorbent carrier, and water is present in an amount of 0.7 to 1.3 mL of water per gram of the solid adsorbent carrier.

[0078] More preferably, The compound is present in an amount of 2.0 to 2.4 mL of the compound per gram of the solid adsorbent carrier, and water is present in an amount of 0.6 to 0.8 mL of water per gram of the solid adsorbent carrier, or The compound is present in an amount of 2.5 to 4 mL of the compound per gram of the solid adsorbent carrier, and water is present in an amount of 0.7 to 1.3 mL of water per gram of the solid adsorbent carrier.

[0079] The embodiment provides a supported secondary amine-based novel adsorbent (AS-3-0.9). The adsorbent was developed with a high CO2 capacity (>2 mmol / g) and excellent stability in high-temperature pure CO2 regeneration. Thus, most preferably, the compound is present in an amount of 3 mL of the compound per gram of the solid adsorbent carrier, and water is present in an amount of 0.9 of water per gram of the solid adsorbent carrier.

[0080] In the contacting step, the secondary amine is selectively covalently bonded to the solid carrier within the pores, i.e., the secondary amine is confined inside the pores of the solid adsorbent carrier. Preferably, thus, the resulting solid adsorbent has a ΔV / V アミノグラフト化 ratio of 0.5 to 1.1, preferably 0.7 to 1.1, more preferably 0.8 to 1.1, even more preferably 0.85 to 1.1, still more preferably 0.85 to 1.05, even still more preferably 0.9 to 1.05, and most preferably 0.95 to 1.02. アミノグラフト化 Ideally, the ΔV / V

[0081] In one embodiment, in the contacting step, the solid adsorbent carrier containing pores is contacted with the compound and water in a single step.

[0082] In other embodiments, in the contacting step, the solid adsorbent carrier containing pores is contacted with the compound in stages. For example, the solid adsorbent carrier containing pores is contacted with the compound by (a) adding a first portion of the compound to the solid adsorbent carrier, and (b) adding one or more additional portions (e.g., 1, 2, or 3 additional portions) of the compound to the solid adsorbent carrier. In one embodiment, the portions are each of equal volume. Preferably, an amount of time (e.g., at least 10 minutes, preferably at least 20 minutes, more preferably at least 30 minutes, most preferably at least 1 hour) elapses before adding the additional portions of the compound to the solid adsorbent carrier.

[0083] In embodiments, the present invention is a method for preparing a solid adsorbent for a carbon dioxide recovery process, the adsorbent comprising a solid adsorbent carrier containing pores, and a secondary amine covalently bonded to the solid adsorbent carrier and confined inside the pores of the solid adsorbent carrier, the method comprising contacting a solid silica adsorbent carrier containing pores with (a) a compound which is a compound of formula (II)

[0084] [Chemical formula] (wherein each X is independently a C1-C6 alkoxy group, n is 2-5, p is 0-4), and (b) water, and the compound is present in an amount of 2.5-4 mL of the compound per gram of the solid adsorbent carrier, and the water is present in an amount of 0.7-1.2 mL of water per gram of the solid adsorbent carrier.

[0085] In other embodiments, the present invention is a method for preparing a solid adsorbent for a carbon dioxide recovery process, the adsorbent comprising a solid adsorbent carrier containing pores, and Covalently bonded to a solid adsorbent carrier and containing a secondary amine confined inside the pores of the solid adsorbent carrier, the method comprising A solid silica adsorbent carrier that is mesoporous MCM-41 (a) A compound that is N-methylaminopropyltrimethoxysilane, and (b) Contacting with water, The compound is present in an amount of 2.0 - 2.4 mL of the compound per gram of the solid adsorbent carrier, The water is present in an amount of 0.6 - 0.9 mL of water per gram of the solid adsorbent carrier, or The compound is present in an amount of 2.5 - 5 mL of the compound per gram of the solid adsorbent carrier, The water is present in an amount of 0.7 - 1.3 mL of water per gram of the solid adsorbent carrier, provides a method.

[0086] In another preferred embodiment, the present invention is a method for preparing a solid adsorbent for a carbon dioxide recovery process, the adsorbent comprising A solid adsorbent carrier containing pores, and Covalently bonded to the solid adsorbent carrier and containing a secondary amine confined inside the pores of the solid adsorbent carrier, the method comprising A solid silica adsorbent carrier that is mesoporous MCM-41 (a) A compound that is N-methylaminopropyltrimethoxysilane, and (b) Contacting with water, The compound is in an amount of 2.5 - 3.5 mL of the compound per gram of the solid adsorbent carrier, The water is present in an amount of 0.8 - 1.2 mL of water per gram of the solid adsorbent carrier, provides a method.

[0087] As described above, the present invention further provides a second solid adsorbent for a carbon dioxide recovery process, the adsorbent comprising A solid adsorbent carrier containing pores, and Covalently bonded to the solid adsorbent carrier and containing a secondary amine confined inside the pores of the solid adsorbent carrier, A second solid adsorbent is provided, wherein the solid adsorbent is obtainable by the method of the present invention.

[0088] The second solid adsorbent of the present invention shares the characteristics and preferred characteristics of the first solid adsorbent as defined above.

[0089] Furthermore, preferably, each of the first and second solid adsorbents of the present invention has a surface area of about 20 to about 80 m 2 / g, more preferably about 25 to about 70 m 2 / g, even more preferably about 25 to about 60 m 2 / g, still even more preferably about 30 to about 50 m 2 / g, and most preferably about 30 to about 40 m 2 / g.

[0090] Preferably, each of the first and second solid adsorbents of the present invention has a pore volume of about 0.15 to about 0.6 cm 3 / g, more preferably about 0.2 to about 0.6 cm 3 / g, even more preferably about 0.2 to about 0.5 cm 3 / g, still even more preferably 0.2 to about 0.35 cm 3 / g, and most preferably about 0.2 to about 0.3 cm 3 / g.

[0091] Preferably, each of the first and second solid adsorbents of the present invention has an average pore diameter of about 26 to about 33 nm, more preferably about 27 to about 32 nm, even more preferably about 28 to about 31 nm, still even more preferably about 29 to about 31 nm, and most preferably about 29 to about 30.5 nm.

[0092] Preferably, therefore, each of the first and second solid adsorbents of the present invention (a) has a surface area of about 20 to about 80 m 2 / g, and / or (b) has a pore volume of about 0.15 to about 0.6 cm 3 / g, and / or (c) It has an average pore diameter of about 26 to about 33 nm.

[0093] More preferably, each of the first and second solid adsorbents of the present invention (a) has a surface area of about 30 to about 50 m 2 / g, and / or (b) has a pore volume of about 0.2 to about 0.35 cm 3 / g, and / or (c) has an average pore diameter of about 29 to about 31 nm.

[0094] Most preferably, each of the first and second solid adsorbents of the present invention (a) has a surface area of about 30 to about 40 m 2 / g, and / or (b) has a pore volume of about 0.2 to about 0.3 cm 3 / g, and / or (c) has an average pore diameter of about 29 to about 30.5 nm.

[0095] The solid adsorbent according to the embodiment may be used in a fixed bed reactor, such as a rotating fixed bed reactor. The solid adsorbent according to the embodiment may alternatively be formed into pellets or powder and used in a fluidized bed reactor or a moving bed reactor. In one particular embodiment, the solid adsorbent according to the embodiment is formed into powder and may be pelletized.

[0096] Therefore, each of the first and second solid adsorbents of the present invention may be an adsorbent for a fixed adsorbent bed or a moving adsorbent bed. Thus, in one embodiment, each of the first and second solid adsorbents of the present invention may be an adsorbent for a fixed adsorbent bed. In other embodiments, each of the first and second solid adsorbents of the present invention may be an adsorbent for a moving adsorbent bed.

[0097] Furthermore, each of the first and second solid adsorbents of the present invention may be an adsorbent in pellet form or powder form. Thus, in one embodiment, each of the first and second solid adsorbents of the present invention may be an adsorbent for pellet form. In other embodiments, each of the first and second solid adsorbents of the present invention may be an adsorbent for powder form. Accordingly, the present invention further provides pellets containing each of the first and second solid adsorbents of the present invention, and powders containing each of the first and second solid adsorbents of the present invention.

[0098] Furthermore, the long-term stability of the adsorbent was investigated by performing TSA cycles under 80% CO2 (423 hours) and flue gas-like mixture (366 hours) in the temperature range of 50 - 145°C. Over this period, no CO2 uptake loss was recorded, indicating that the material maintained its thermochemical stability against leaching, oxidative decomposition, and urea formation. This demonstrates the high potential of the adsorbent for use in a CO2 recovery process using TSA / CO2 as a desorption strategy. Furthermore, the performance of the adsorbent at various CO2 concentrations and temperatures was evaluated, showing very good reaction rates and CO2 capacities at very low PCO2. As a result, the adsorbent can recover CO2 from ppm values (e.g., direct air capture) to flue gas concentrations in power plants and can manipulate the concentration gradient in the adsorbent bed. Furthermore, the regeneration of the adsorbent is particularly advantageous because the regeneration heat is close to 0 MJ / kg CO2 and only sensible heat is required.

[0099] Thus, as described above, the present invention is a method for regenerating a solid adsorbent for a carbon dioxide recovery process, wherein the solid adsorbent containing carbon dioxide is heated at a temperature of 120 - 150°C to release the carbon dioxide contained in the solid adsorbent, and the solid adsorbent is the solid adsorbent according to the present invention.

[0100] Preferably, the solid adsorbent containing carbon dioxide is heated at a temperature of 130 - 145°C, more preferably at a temperature of about 130 - 140°C, and most preferably at a temperature of about 134°C.

[0101] Preferably, the solid adsorbent containing carbon dioxide is heated in an atmosphere containing carbon dioxide, preferably an atmosphere containing 10 to 100 vol% of carbon dioxide, more preferably an atmosphere containing 40 to 100 vol% of carbon dioxide, still more preferably an atmosphere containing 60 to 100 vol% of carbon dioxide, even more preferably an atmosphere containing 70 to 100 vol% of carbon dioxide, and most preferably an atmosphere containing about 100 vol% of carbon dioxide.

[0102] Accordingly, in an embodiment, the present invention is a method for regenerating a solid adsorbent for a carbon dioxide recovery process, wherein the solid adsorbent containing carbon dioxide is heated at a temperature of 130 to 145 °C in an atmosphere containing 60 to 100 vol% of carbon dioxide to release the carbon dioxide contained in the solid adsorbent, and the solid adsorbent is the solid adsorbent according to the present invention, and provides a method.

[0103] In another embodiment, the present invention is a method for regenerating a solid adsorbent for a carbon dioxide recovery process, wherein the solid adsorbent containing carbon dioxide is heated at a temperature of 130 to 140 °C in an atmosphere containing 70 to 100 vol% of carbon dioxide to release the carbon dioxide contained in the solid adsorbent, and the solid adsorbent is the solid adsorbent according to the present invention, and provides a method.

[0104] Furthermore, as described above, the present invention further relates to the use of a solid adsorbent in the adsorption of carbon dioxide, wherein the adsorption of carbon dioxide is carried out at a temperature of less than 100 °C, and the solid adsorbent is the solid adsorbent according to the present invention, and provides a use.

[0105] Preferably, the adsorption of carbon dioxide is carried out at a temperature of 0 to 100 °C, more preferably at a temperature of 20 to 80 °C, still more preferably at a temperature of 30 to 70 °C, and most preferably at a temperature of 40 to 60 °C.

[0106] In an embodiment, carbon dioxide is adsorbed from air. Thus, in an embodiment, the present invention provides the use of a solid adsorbent in the adsorption of carbon dioxide by direct air capture, wherein the solid adsorbent is the solid adsorbent according to the present invention.

[0107] In other embodiments, carbon dioxide is adsorbed from flue gas.

[0108] Thus, in an embodiment, the present invention provides the use of a solid adsorbent in the adsorption of carbon dioxide from flue gas, wherein the adsorption of carbon dioxide is carried out at a temperature of 20 to 80 °C, and the solid adsorbent is the solid adsorbent according to the present invention.

[0109] In other embodiments, the present invention provides the use of a solid adsorbent in the adsorption of carbon dioxide from flue gas, wherein the adsorption of carbon dioxide is carried out at a temperature of 40 to 60 °C, and the solid adsorbent is the solid adsorbent according to the present invention.

[0110] Furthermore, as described above, the present invention further provides the use of a solid adsorbent in a carbon dioxide recovery process that uses temperature swing adsorption with carbon dioxide purge as a desorption strategy, wherein the solid adsorbent is the solid adsorbent according to the present invention.

[0111] Preferably, the carbon dioxide recovery process includes the adsorption of carbon dioxide as defined above. More preferably, the carbon dioxide purge includes a method for regenerating the solid adsorbent for the carbon dioxide recovery process as defined above, and the solid adsorbent containing carbon dioxide is heated in an atmosphere containing carbon dioxide.

[0112] Thus, in an embodiment, the present invention provides the use of a solid adsorbent in a carbon dioxide recovery process that uses temperature swing adsorption with carbon dioxide purge as a desorption strategy, (a) the solid adsorbent is the solid adsorbent according to the present invention, (b) The carbon dioxide recovery process includes the adsorption of carbon dioxide, and the adsorption of carbon dioxide is carried out at a temperature below 100 °C. (c) The carbon dioxide purge provides for use including a method in which a solid adsorbent containing carbon dioxide is heated at a temperature of 120 - 150 °C in an atmosphere containing carbon dioxide to release the carbon dioxide contained in the solid adsorbent.

[0113] In a preferred embodiment, the present invention is the use of a solid adsorbent in a carbon dioxide recovery process that uses temperature swing adsorption as a desorption strategy, (a) The solid adsorbent is the solid adsorbent according to the present invention. (b) The carbon dioxide recovery process includes the adsorption of carbon dioxide from flue gas, and the adsorption of carbon dioxide is carried out at a temperature of 40 - 60 °C. (c) The carbon dioxide purge provides for use including a method in which a solid adsorbent containing carbon dioxide is heated at a temperature of 130 - 140 °C in an atmosphere containing 70 - 100 vol% carbon dioxide, most preferably 100 vol% carbon dioxide, to release the carbon dioxide contained in the solid adsorbent.

[0114] Definition of parameters In this specification, the density of the secondary amine (expressed in amine groups / nm 2 is determined by the following formula.

[0115]

Equation

[0116] In the formula, Δw is the weight loss per gram of the adsorbent (g) in calcination in air at 120 - 800 °C determined by thermogravimetric analysis.

[0117] M cis the molecular weight lost upon calcination per secondary amine unit. When the secondary amine is derived from an aminosilane compound, the molecular weight lost upon calcination per secondary amine unit is calculated as the average molecular weight lost per secondary amine unit of a conceptual aminosilane hexamer containing three silane units with pendant alkoxy groups and having two oxygen atoms per silicon atom, and three silane units with pendant hydroxyl groups (see Figure 13, Structure 1). The lost molecular weight is assumed to be the sum of the molecular weights of six amino groups, three alkyl radicals (derived from three alkoxy groups), two hydrogen atoms, and one hydroxyl radical (derived from three hydroxyl groups). Therefore, the average molecular weight lost per secondary amine unit is the decrease in the molecular weight of the hexamer divided by six. When N-MAPTMS is used as the aminosilane, the molecular weight lost upon calcination per secondary amine unit is 83 g / mol (see the conversion from Structure 1 to Structure 2 in Figure 13).

[0118] For ease of calculation, note that the concentration of the N functional group (mmol N / g 吸着剤 ) is as follows.

[0119]

Number

[0120] Therefore, the above formula may be rearranged for convenience so that the concentration of the N functional group appears in the molecule.

[0121] NA is Avogadro's number (6.02214076·10 23 ).

[0122] Formula

[0123]

Number

[0124] is the surface area of the support per gram of adsorbent (nm of the support in 1 gram of adsorbent2 ) is provided.

[0125] SA is the surface area of the carrier (i.e., foamed MCM-41) determined as defined below in m 2 / g.

[0126] M g is the molecular weight added to the carrier per secondary amine unit. When the secondary amine is derived from an aminosilane compound, the molecular weight added to the carrier per secondary amine unit is calculated as the average molecular weight added per secondary amine unit of a conceptual aminosilane hexamer containing three silane units with pendant alkoxy groups having two oxygen atoms per silicon atom and three silane units with pendant hydroxyl groups (see Figure 13, Structure 1). The added molecular weight is assumed to be the sum of the molecular weights of six silicon atoms, twelve oxygen atoms, six amino groups, three alkyl radicals (derived from three alkoxy groups), and three hydrogen atoms (derived from three hydroxyl groups). Therefore, the average molecular weight added per secondary amine unit is the molecular weight added by the hexamer divided by six. When N-MAPTMS is used as the aminosilane, the molecular weight added to the carrier per secondary amine unit is 143 g / mol (see Figure 13, Structure 1).

[0127] Calculation example of the density of the secondary amine of AS-3-0.9

[0128]

Equation

[0129] In this specification, the value ΔV is determined by the following formula. ΔV = V 担体 - V 吸着剤 V 担体 is the pore volume of the carrier contained in 1 g of the adsorbent (expressed in cm 3 / g). V 担体 = m s ·PV 担体 PV 担体 is the pore volume of the carrier per gram of the carrier (expressed in cm 3 / g) as determined by the BJH method. m s is the calculated mass (g) of the carrier contained in 1 gram of the adsorbent. m s = 1 - m アミノグラフト化 m アミノグラフト化 is the mass (g) of each secondary amine unit (i.e., amino silane derivative unit) covalently bonded to the solid adsorbent carrier per gram of the adsorbent.

[0130]

Equation

[0131] V 吸着剤 is the pore volume of the adsorbent contained in 1 g of the adsorbent (expressed in cm 3 / g). V 吸着剤 = PV 吸着剤 PV 吸着剤 is the pore volume of the adsorbent per gram of the adsorbent (expressed in cm 3 / g) as determined by the BJH method.

[0132] In this specification, the value of V アミノグラフト化 is determined by the following equation:

[0133]

Equation

[0134] where ρ 試薬 is the density (g / cm 3 ) of the compound that provides the secondary amine, i.e., the compound used to form the adsorbent (i.e., the compound used in the method of the present invention, preferably amino silane). When N-MAPTMS is used as the compound (i.e., amino silane), ρ 試薬 is 0.978 g / cm 3It is.

[0135] ΔV / V of AS-3-0.9 アミノグラフト化 Calculation example for the ratio:

[0136]

Number

[0137] V 吸着剤 = PV 吸着剤 = 0.23 cm 3 / g ΔV = V 担体 - V 吸着剤 = 0.76 - 0.23 = 0.53 cm 3 / g

[0138]

Number

[0139] ΔV / V アミノシラン = 0.53 / 0.5584 = 0.96

[0140] In this specification, the surface area (expressed in m 2 / g) is determined by N2 physical adsorption using the BET (Brunauer - Emmett - Teller) method.

[0141] In this specification, the pore volume (expressed in cm 3 / g) is determined by N2 physical adsorption using the BJH (Barrett - Joyner - Halenda) method.

[0142] In this specification, the average pore diameter (expressed in nm) is determined by N2 physical adsorption using the BJH (Barrett - Joyner - Halenda) method.

[0143] The results demonstrating the performance of the adsorbent according to the embodiment are shown below.

[0144] Characterization of PE-MCM-41 and N-MAPTMS-Modified Materials The structural properties of PE-MCM-41 and AS-X-Y obtained based on N2 physical adsorption technology are summarized in Table 1 shown in Figure 9. The nitrogen adsorption-desorption isotherms and pore size distributions of PE-MCM-41, AS-(1-5)-0.6, and AS-3-(0.6-1.2) are shown in Figure 1. According to the IUPAC classification, the N2 adsorption-desorption isotherm of PE-MCM-41 is type IV with a type H1 hysteresis loop (Figure 1a). This indicates the presence of a narrow range of uniform mesopores in the silica material. In addition to the recorded loop, there is an adsorption-desorption step within the relative pressure range of 0.25 to 0.4, which indicates the filling of mesopores. In this case, the mesopores have an inner width within the lower limit range of the mesopore region (e.g., 2 to 50 nm according to IUPAC). Figure 1b shows the bimodal pore size distribution of PE-MCM-41 determined by the BJH method. The first peak is distributed in a narrow pore size range of 2 to 4 nm with a maximum at 2.5 nm and corresponds to the pore filling step seen on the adsorption-desorption isotherm. On the other hand, the second peak spreads almost throughout the entire mesopore region, further enters the lower limit of the mesopore range, and records a maximum at 30 nm. The same analysis was performed on the N-MAPTMS-modified samples. The effects of the amino silane / SiO2 and H2O / SiO2 ratios on the texture properties of the PE-MCM-41 structure are shown in Figures 1a, b and 1c, d respectively. Prior to grafting, PE-MCM-41 had a surface area of 905 m 2 / g, a pore volume of 1.6 cm 3It had a pore volume of / g and an average pore diameter of 7.4 nm. After grafting, when the aminosilane / SiO2 increased from 1 to 5 for the same H2O / SiO2 ratio of 0.6, the surface area and pore volume decreased significantly. However, the decrease was not continuous from 1 to 5, and it was minimized at X = 2. In the case of the average pore diameter, an increase was seen up to X = 2, and then it decreased (Table 1). The increase in the average pore diameter with the grafting rate is due to the filling of small pores within the first and second peak ranges. The first peak disappeared from the pore size distribution of the grafted sample, and the second peak shifted to a larger pore diameter (Figure 1b). As shown in Figure 1a, when fixing aminosilane on the surface of the SiO2 pore structure, the N2 adsorption isotherm maintained Type IV with hysteresis H1. Furthermore, the pore filling step in the relative pressure range of 0.25 - 0.4 disappeared to pack aminosilane into small pores.

[0145] The addition of water clearly enhances the grafting process through the following: (i) increasing the density of silanol groups on the silica surface, thus increasing the possibility of contact between alkoxy - hydroxyl groups, and (ii) promoting the formation of siloxanes by hydrolysis and condensation of the alkoxy groups of aminosilanes with silanol groups from the silica surface and among themselves [References: 19, 35, 37]. Nevertheless, aminoalkoxysilanes each correspond to the hydrolysis - condensation reaction, specifically due to the nature of the amino - alkyl chain and alkoxy groups [References: 38 - 40]. Brochier Salon et al. [Reference: 38] studied the reaction rates of the hydrolysis and condensation reactions of various alkoxysilanes, and the results showed that the presence of basic groups in the silane molecule increased the self - condensation reactivity, leading to a 3D structure. Furthermore, they also emphasized the inhibitory effect of the steric - electronic hindrance of long chains and aromatic rings on self - condensation. This ultimately promotes the careful investigation of the alkoxysilanes selected through research. Therefore, in this specification, the influence of H2O on the grafting of AS - 2 - Y and AS - 3 - Y was investigated. The samples were selected based on their highest N content and best CO2 adsorption performance (Figure 2a, 4a). Figures 1c, d show the type IV N2 adsorption isotherm and unimodal pore size distribution of the AS - 3 - Y sample. The surface area and pore volume decreased significantly with the increase in water content for the AS - 2 - (0.6 - 0.8) and AS - 3 - (0.6 - 0.9) samples (Table 1). A further increase in the water / silica ratio to 1.2 affected the grafting rate of both the AS - 2 - 1.2 and AS - 3 - 1.2 samples, as an increase in surface area and pore volume was observed.

[0146] Thermogravimetric analysis of the PE-MCM-41 and AS-X-Y products was carried out to quantify the organic fragments of the grafted aminosilane. As described in the Methods section, the weight loss recorded at 150 - 800 °C in an oxygen atmosphere was considered for the calculation of the nitrogen content (Table 1). The weight loss of PE-MCM-41 was measured and subtracted from the loss obtained for the AS-X-Y sample. Figure 2a shows the change in nitrogen concentration, the ratio of the reduced pore volume (ΔV, BJH method), and the volume of the grafted aminosilane (V アミノグラフト化 , TGA calcination) at the N-MAPTMS / SiO2 ratio. ΔV was calculated considering 1 g of the support with subsequent filling with aminosilane (as described above), while the aminosilane capacity was calculated based on the TGA calcination and the initial aminosilane density (as described above). The ΔV / V アミノグラフト化 ratio value indicates the approximate location of the aminosilane. For ratios of 1, >1, and <1, the aminosilane is well positioned inside the support pore volume by surface grafting, shows pore blockage, and is externally deposited to some extent, respectively. When the aminosilane / support ratio is increased to 2, ΔV / V アミノグラフト化A significant increase in the ratio and nitrogen content is observed (Figure 2a), which then decreases with further addition of aminosilane. Among the factors are the change of aminosilane to the SiO2 ratio by varying the aminosilane concentration, various diffusion rates, and the hydrolysis and condensation rates by varying the aminosilane to the water ratio. At relatively low aminosilane concentrations, the enhanced diffusion with the increase in the aminosilane / carrier ratio is dominant, while at relatively high aminosilane concentrations, fast self-condensation in the solution without being fixed on the carrier surface is dominant, reducing the reaction inside the pores. Harlick et al. [Reference: 18], Linneen et al. [Reference: 41], and Kim et al. [Reference: 42] also studied the effect of the amount of aminosilane (triamine [References: 18, 41] and diamine [Reference: 42]) on the grafting efficiency in the absence of water. Interestingly, Harlick et al. [Reference: 18], Linneen et al. [Reference: 41] each reported a sharp step in the grafting effectiveness at 2 and 1 mL of aminosilane per g of SiO2, with the nitrogen content steadily increasing as the aminosilane / silica ratio increases and finally reaching a plateau as the further aminosilane / SiO2 ratio increases. In contrast, the study by Kim et al. [Reference: 42] found a constant N content within the range of 0.67 - 1.11 g / g of the aminosilane / SiO2 ratio, which then decreased sharply when the ratio increased to 2.22 g / g, which was hypothesized to be the result of non-uniform grafting throughout the porous medium due to pore opening blockage caused by an overly high aminosilane concentration during supply. In this specification, all ΔV / V of AS-X-0.6 アミノグラフト化 ratios are less than 1.

[0147] Figure 2b shows the change in the ΔV / V アミノグラフト化 ratio and nitrogen content with the H2O / PE-MCM-41 ratio of the AS-3-Y adsorbent. It can be seen the important role of water in the hydrolysis and condensation of alkoxy groups. The increase in water concentration enhanced the hydration of the silica surface that promotes the bonding of the alkoxy groups of aminosilane, and then aminosilane self-condensed, gradually filling the pore volume. The AS-3-0.9 adsorbent has a ΔV / V of 1.01アミノグラフト化 The case where the ratio is reached and all the aminosilane polymer is confined inside the carrier pore volume is shown. Linneen et al. [Reference: 41] and Harlick et al. [Reference: 19] studied the effect of the addition of water to triamine-functionalized silica. Interestingly, both studies reported the maximum amine loading at a water / SiO2 ratio of 0.3 mL / g. Further increases in the water content did not increase the N content beyond this point, causing a plateau. A similar behavior was observed by the inventors of the embodiments for the case of AS-3-Y. When the H2O / PE-MCM-41 ratio reached 0.7, the N content increased up to 3.6 mmol N / g and then leveled off. The ΔV / V observed with a further increase in the water / PE-MCM-41 ratio to 1.2 アミノグラフト化 The decrease in the ratio and the slight increase in the N content may be due to the relatively high water / aminosilane ratio used in AS-3-1.2. Rapid hydrolysis-condensation of the aminosilane outside the porous medium can occur at an overly high water / aminosilane ratio, resulting in a decrease in the active material [Reference: 38]. This can be confirmed by the fact that when the grafting process is carried out in toluene, sticky lumps develop over time and are deposited in the flask at high water / aminosilane ratios (e.g., in the case of AS-2-1.2, AS-1-0.6).

[0148] Figure 3 shows the XRD spectra of the PE-MCM-41 and AS-3-Y samples. Only the (100) reflection was detected at 2θ = 2.3°, and the decaying peak shoulders may correspond to the (110) and (200) reflections at 2θ = 3.5 - 4.5°, indicating the short-range order of the hexagonal structure of PE-MCM-41 [Reference: 43]. The intensity of the (100) reflection changed substantially during the fixation and polymerization of more aminosilanes in the porous silica structure. This indicates that the d-spacing (d(100)) decreased continuously when the pore occupancy by amine functional groups increased gradually [Reference: 44]. As the water / silica ratio increased from 0.6 to 0.8 and then remained almost constant between 0.8 and 1.2, the (100) reflection intensity decreased gradually. The flat region of the reflection intensity observed between 0.8 and 1.2 coincides with the flat region of the nitrogen content (Figure 2b), indicating the effective graft polymerization of aminosilanes inside the porous medium of PE-MCM-41. Apart from the decrease in the (100) reflection intensity when the water / silica ratio of the AS-3-Y sample increased, a gradual change in decreasing 2θ from 2.3° to 1.65° was also observed, indicating a shift to larger cell characteristics. At first glance, it seems to be inconsistent with the literature because the peak should move to a larger angle when the cell parameter is reduced [References: 43, 45 - 47]. However, considering the bimodal structure of PE-MCM-41, the average pore diameter changes to a larger value by first confining the smaller-diameter pores (Table 1). This explains the progressive shift of the (100) reflection to lower 2θ.

[0149] CO2 sorption Figure 4a illustrates the effect of the addition of N-MAPTMS on the CO2 adsorption efficiency and capacity at 5 vol% CO2 and 40 °C for 60 minutes. AS-2-0.6 achieved the highest CO2 uptake of 1.48 mmol / g and an efficiency of 0.43, followed by AS-3-0.6 (1.06 mmol / g and 0.37), AS-5-0.6 (1.02 mmol / g and 0.39), and AS-1-0.6 (0.77 mmol / g and 0.32). These trend changes are related to the N content and ΔV / V アミノグラフト化It is consistent with what was observed for the ratio (Figure 2a) and shows a relatively good dispersion of the aminosilane and easily accessible amine sites. It is widely accepted in the literature that two amine sites (primary and / or secondary) are required to adsorb one CO2 molecule in the anhydrous state, which is a reaction related to the formation of carbamate through the deprotonation of the zwitterion intermediate by a base (base = amine in this specification) [References: 17, 21, 47 - 51]. Considering this, approximately 70% of the amine sites in the AS-(2 - 5)-0.6 sample are involved in carbamate formation, which is a fairly high proportion considering that adsorption can be hindered by various factors. One of these is the amine density, which has been shown to be important in obtaining a high adsorption efficiency [References: 49 and 51]. Hori et al. [Reference: 49] grafted primary aminosilane (APTMS) onto MCM-41 and SBA-15, and interestingly, for the same aminosilane loading, a small pore diameter structure such as MCM-41 (2.9 nm) reached a higher CO2 adsorption capacity compared to SBA-15 (6.2 nm) and SBA-15 (10.6 nm). It was suggested that carbamate formation is more effective in small pores because the amine sites can form carbamates not only with nearby amines but also with those located on the opposite half of the pore considering polymerization in the layer. This may be exploitable for the bimodal pore structure of PE-MCM-41 according to the embodiment, since pores that are overly large (20 - 60 nm) may be less effective than smaller ones. Furthermore, considering the very large surface area and pore volume of the PE-MCM-41 support, an overly low aminosilane / silica ratio causes a low density of aminosilane as in the case of the AS-1-0.6 sample, and thus can reduce the effectiveness of carbamate formation even for nearby amines. Additionally, the aminosilane used in the studies conducted by the inventors of the embodiment is sterically more constrained by its attached methyl group than primary amine or primary-secondary diamine molecules, making carbamate formation more difficult.Steric hindrance of the carbamate complex is another factor, which also hinders the entry of CO2 into the inner free amine site and can result in an efficiency of less than 0.5 [References: 52, 53]. Furthermore, according to Linneen et al., water must be regarded as the main component in this study [Reference: 41], and the water layer / pocket on the silica surface can stimulate the rapid polymerization of aminosilane and become a substantial hindrance site for CO2 transport.

[0150] The influence of the water / SiO2 ratio on the CO2 adsorption performance of the AS-3-Y sample is shown in Fig. 4b. The trend in CO2 capacity is consistent with that observed for the nitrogen content and ΔV / V アミノグラフト化 ratio (Fig. 2b). The maximum CO2 capacity was achieved at AS-3-0.9 with 1.94 mmol / g, followed by AS-3-1.2 with a nearly similar value of 1.90 mmol / g, and then decreased to 1.84, 1.67, and 1.06 mmol / g for the AS-3-0.8, AS-3-0.7, and AS-3-0.6 samples, respectively. The CO2 adsorption efficiency follows a similar behavior, demonstrating that a high-density amino-based skeleton developed along the high surface area and the pore volume (ΔV / V アミノグラフト化 →1) is essential for manipulating the adsorption efficiency to a value close to the theoretical value (0.5). The N surface density (amine groups / nm 2 ) was calculated for all of the adsorbents (Table 1, Fig. 4c), showing the dependence of CO2 adsorption efficiency on the distance between the adsorption sites. Fig. 4c shows that when the N surface density approaches 5 amine groups / nm 2 , it is easy to obtain an efficiency close to the theoretical value. At this point, it is important to examine the pore diameter of the carrier. Hori et al. [Reference: 49] showed that for the same N surface density, an increase in pore diameter decreased the CO2 adsorption capacity. This is because spreading the polymer across the entire cross-sectional area of the pore increases the possibility of amine groups encountering other amine groups in its immediate vicinity.

[0151] In addition to high CO2 adsorption capacity, the CO2 adsorption reaction rate is another essential measurement criterion to consider when evaluating the effectiveness of adsorbents. Due to its high CO2 capacity, the AS-3-0.9 sample was selected for the study of reaction rate at 40, 50, and 60 °C for 56 minutes with 5% CO2 / N2. The uptake curves under different conditions are shown in Fig. 5a. When the adsorbent was exposed to the gas mixture, an immediate increase in CO2 uptake occurred, reaching 90.7%, 95.1%, and 97.6% of the maximum capacity (at 56 minutes) at 40, 50, and 60 °C, respectively, in just 3 minutes. This supports the idea that the combination of high surface area, pore volume, and pore diameter provides not only good dispersion of a large amount of aminosilane but also promotes fast CO2 diffusion to amine sites, despite the low regularity and bimodal structure of MCM-41. Furthermore, due to the exothermic nature of the CO2-amine reaction [References: 18, 45, 47, 48], the temperature drop from 60 to 40 °C resulted in an increase in CO2 capacity from 1.66 to 1.93. Similar trends were obtained for various grafted amine adsorbents or modified amine-based polymers such as TEPA and PEI [References: 24, 25, 28, 41]. Linneen et al. [Reference: 41] performed dry grafting of mono, di, and tri-aminoalkoxysilanes and obtained a similar decreasing trend in CO2 uptake with increasing temperature. The same was seen even when wet grafting of Tri was carried out [Reference: 28]. However, in the case of the long amino-alkyl chain of TRI, the lower pore volume and surface area of the carrier such as silica gel [Reference: 35], and / or the high degree of polymerization of Tri [Reference: 41] may increase the inaccessibility of amine sites and cause better performance at higher temperatures. This phenomenon is frequently observed in adsorbents prepared by impregnation of amine-based polymers such as PEI, TEPA, and PEHA into porous materials [References: 9, 25, 54 - 57]. High polymer loading and / or high polymer impregnation prohibit the mobility of amine sites and the movement of CO2 through the sticky medium. To increase mobility, Yamada et al. [Reference: 25] converted the primary amines of TEPA to secondary amines by bonding various hydroxyl-alkyl and alkyl chains.The results showed that the alkyl-modified TEPA had improved CO2 diffusion compared to the initial TEPA or the hydroxyl-alkyl-modified TEPA. The increased amine flexibility was typically due to a decrease in the hydrogen bonds formed between the amines and the amine-hydroxyl groups. A similar aspect could also be applicable to the aminosilanes used in this study if the amines had methyl groups attached to them, which would prevent the formation of hydrogen bonds with adjacent amines.

[0152] Figure 5b shows the CO2 adsorption isotherms of the AS-3-0.9 sample within a CO2 pressure range of 0.02 - 80 kPa (balanced N2 / He, total flow rate: 100 mL / min, 101 kPa) at 40, 50, and 60 °C. In the low CO2 pressure range of 0.02 - 5 kPa, all the isotherms showed a sharp increase, indicating a strong CO2-amine interaction [References: 17, 30, 58]. With a further increase in the CO2 partial pressure up to 80 kPa, although with a rather low slope, the CO2 capacity of the adsorbent increased. Serna-Guerrero et al. [Reference: 30] confirmed the fact that at CO2 partial pressures higher than 5%, CO2 physisorption occurs simultaneously with chemisorption, resulting in a CO2 / N efficiency exceeding 0.5. In this specification, at 40 °C and CO2 partial pressures of 5, 40, and 80 kPa, AS-3-0.9 recorded CO2 capacities of 1.95, 2.24, and 2.29 mmol / g, meaning CO2 / N efficiencies of 0.44, 0.5, and 0.51, respectively. In this case, it is difficult to define the uptake fractions of chemisorbed and physisorbed CO2. The adsorbent reached saturation of the accessible amines at 5 kPa, P CO2The CO2 uptake after >5 kPa may be due to physical adsorption. Nevertheless, the CO2 / N efficiency achieved at 40 °C and 5 kPa is quite close to the theoretical value, indicating both a very high density of secondary monoamine skeletons and accessible amine sites in the AS-3-0.9 sample, which are two major factors for the efficient formation of carbamates. The CO2 uptake of the adsorbent decreases continuously as the CO2 partial pressure drops below 5 kPa. Since the CO2 concentration in post-combustion NGCC power plants is in the range of 3 - 5 vol%, it is important to maintain a high CO2 capacity within this range and even at lower concentrations. It is also necessary to consider the concentration gradient across the adsorbent bed, which means that the adsorbent must have a high affinity for CO2 molecules even in ultra-dilute gas mixtures containing 200 - 1000 ppm of CO2. At 40 °C and Pco2 of 3, 1, and 0.03 kPa, the AS-3-0.9 adsorbent achieved capacities of 1.88, 1.73, and 0.94 mmol CO2 / g, respectively. Belmabkhout et al. [Reference: 28] performed the CO2 adsorption isotherm of TRI-PE-MCM-41 in the CO2 partial pressure range of 0.04 - 5 kPa. At 35 °C and P CO2 of 3, 1, and 0.04 kPa, CO2 capacities of 1.68, 1.4, and 0.98 mmol / g were obtained, respectively. If TRI-PE-MCM-41 has an amine loading of 7.9 mmol / g, the adsorbent developed in this study functioned significantly better at low CO2 concentrations while having a substantially lower nitrogen content of 4.46 mmol / g when compared to TRI-PE-MCM-41. Anyanwu et al. [Reference: 35] obtained a CO2 capacity of 1.098 mmol / g on a TRI-silica gel adsorbent at 25 °C and 415 ppm. A similar capacity was obtained with AS-3-0.9 at 40 °C.

[0153] Figure 5c illustrates the CO2 adsorption capacity versus time for the AS-3-0.9 sample at 40 °C and in the CO2 pressure range of 0.03 - 80 kPa. As the CO2 partial pressure gradually decreases from 5 to 0.03 kPa, the time required to reach the maximum capacity corresponding to each phase equilibrium increases. At 5, 3, and 1 kPa, the AS-3-0.9 adsorbent functions significantly, reaching 90% of the maximum capacity in less than 2.6, 3.5, and 5 minutes, respectively. Even at a low pressure of 0.1 kPa, the adsorbent achieved 90% of its equilibrium capacity in just 13 minutes. Little research has investigated the N-MAPTMS structure. Ko et al. [Reference: 47] and Zelenak et al. [Reference: 48] performed dry grafting of N-MAPTMS onto SBA-15 and SBA-12, obtaining nitrogen contents of 3.07 and 2.16 mmol / g, respectively. At 25 °C, the adsorbent of Ko et al. [Reference: 47] acquired 90% of the maximum coverage corresponding to P CO2 of 101 kPa (0.75 mmol CO2 / g) after 25 minutes, while the adsorbent of Zelenak et al. [Reference: 48] functioned in approximately 5 minutes at 10% CO2 / N2 (equilibrium CO2 capacity of 1.06). Considering the low CO2 concentrations used in the investigations by the inventors of the embodiments, it can be inferred that the AS-3-0.9 adsorbent was superior in terms of reaction rate and total adsorbed CO2 capacity compared to other adsorbents.

[0154] Long-term cycle stability The long-term stability of the AS-3-0.9 adsorbent in a CO2-rich stream was evaluated in a series of 205 TSA cycles at sorption / desorption temperatures of 50 and 145 °C in an 80% CO2 / N2 gas mixture. Figure 6 shows the stability results, as well as the weight change and temperature profiles for two cycles. Over 204 cycles and 423 hours of flow-on time, the AS-3-0.9 adsorbent maintained its adsorption capacity, demonstrating its exceptional chemical and thermal stability. The weight change profile indicates that a temperature of 145 °C thermodynamically favors maximum desorption in 80% CO2 / N2. Sayari et al. [References: 17, 36] carefully studied the stability of various amine structures containing N-MAPTMS. Their results showed significant stability of N-MAPTMS in a CO2-rich atmosphere up to 200 °C without signs of deactivation. IR-NMR investigations have already shown that when different amine structures are exposed to a CO2-rich gas mixture and high temperatures, they form stable urea species, which is an important cause of adsorbent deactivation. The DRIFT and MAS NMR studies by Sayari et al. [Reference: 36] showed that combinations of primary amines, primary-secondary, and secondary-secondary amines (e.g., aminoalkoxysilanes (Di, Tri), polymers (L-PEI, B-PEI)) undergo rapid deactivation in a dry CO2 atmosphere and at high temperatures up to 130 - 150 °C, forming open-chain and cyclic urea species. [Reference: 10], The investigations by Li et al. [Reference: 59] showed a detailed analysis of linear and branched PEI structures. According to their DRIFT results, branched PEI with a molecular weight of 600 Da began to develop a significant urea peak at 75 °C and grew very rapidly when the temperature was raised to 121 °C. The pMONO and Tri adsorbents by Sayari et al. [References: 17, 60] lost 21% between 60 cycles and 14% between 40 cycles at 55 and 50 °C, respectively, under pure CO2. Two routes for amine deactivation to urea species have been proposed [References: 17, 36]. The first is based on the generation of isocyanate by the dehydration of carbamic acid, which causes the formation of urea by subsequent interaction with adjacent amines, while the second involves the formation of urea by the dehydration of ammonium carbamate.For two available hydrogen atoms, isocyanate can only be produced from primary amines, while the nature of the subsequent adjacent amine for urea formation is not important. These mechanisms were further confirmed by testing the stability of the adsorbent in a humid CO2 atmosphere, and it was proven that the presence of water hinders carbamic acid / ammonium carbamate from dehydration even at high temperatures of 105 - 130 °C [References: 10, 59, 60]. Nevertheless, the TSA process based on desorption with pure CO2 and high temperature requires a stable adsorbent in a dry CO2 environment. Desorption with CO2 and water may not be the best approach as water is involved in the formation of bicarbonate, causing a deviation in the CO2 / N stoichiometry from 0.5 to 1 [References: 30, 61]. Furthermore, when using water, the TPD data of Huang et al. [Reference: 61] and Serna-Guerrero et al. [Reference: 30] show a shift of the maximum value of the desorption peak to a higher temperature, meaning a stronger bond in the bicarbonate over the carbamate. A CO2 / N stoichiometry of 1 is advantageous in the adsorption stage, but it is expensive in the desorption step as higher temperatures may be required to achieve a reasonable working capacity. To confirm this aspect, TPD analysis was performed on the AS-3-0.9 sample in the dry and wet states at 40 and 50 °C in 1% CO2 with or without 2.3 or 3% H2O, and then the adsorbed CO2 was released with a temperature ramp of 5 °C / min up to 120 °C.

[0155] Since the CO2 quantified in the dry state based on the MS signal was significantly lower (almost half) than the CO2 estimated from the weight gain, only the MS signal was used to estimate the signal ratio from dry and wet adsorption for the same adsorbent amount. The observations made show little substantial shift at the highest temperature, suggesting that the presence of water during the adsorption stage is unlikely to be a significant issue for the desorption temperature required. Additionally, a larger CO2 MS peak was obtained when adsorption was carried out in the wet state compared to the dry state, demonstrating that CO2 adsorption is enhanced in the presence of water. The ratios of the MS signals obtained in a wet atmosphere at 40 °C - 2.3% H2O, 40 °C - 3% H2O, and 50 °C - 3% H2O and their dry counterparts are 1.33, 1.24, and 1.25, respectively. Based on these findings, it can be inferred that the CO2 uptake of AS-3-0.9 can reach at least 2.4 - 2.6 mmol / g.

[0156] Figure 7 shows the long-term stability of the AS-3-0.9 adsorbent in a gas mixture with a composition equivalent to flue gas from a natural gas power plant. Compared to the previous long-term tests, this faces the influence of oxygen and water in addition to CO2 on the properties of the adsorbent during the adsorption stage. Based on the findings obtained, when desorption was achieved in a dry state (Ar), deactivation did not occur for 99 cycles (366 hours). However, when desorption was carried out in a humid environment (4% H2O), the stability decreased considerably during the first 60 cycles before reaching a plateau due to the low mechanical stability in the presence of water at a high temperature (140 °C) as presumed. Nevertheless, the presence of water is unnecessary in the desorption unit due to the predicted high costs of steam generation and adsorbent drying. In addition to the aspect of stability, it should be noted that the weight gain is the total weight resulting from both water and CO2 adsorption. Since MS-based CO2 quantification is inaccurate, the above ratio of 1.25 for the wet and dry MS signals can be used to estimate the total CO2 adsorbed in the wet state. Considering a CO2 capacity of 1.82 mmol / g in 5% CO2 at 50 °C, the CO2 capacity in the presence of 3% H2O is 2.28 mmol / g (100.1 mg / g). Water adsorption contributes as bicarbonate formation and / or simply physically adsorbed water, accounting for the remaining 20 mg / g (1.1 mmol / g).

[0157] The findings in FIGS. 6 and 7 clearly show the excellent thermal and chemical stability of the AS-3-0.9 adsorbent, which is an important advantage of the adsorbent according to the embodiments. Impregnated adsorbents such as PEI, TEPA, PEHA, and diethanolamine have significant CO2 capacities due to their high density of amine sites, but their long-term thermal stability is poor, especially when regeneration is carried out at temperatures above 75 °C [Reference: 62]. Liu et al. [Reference: 63] studied the stability of PEI (MW = 800)-MCF by performing desorption at 105 °C for 10 minutes during 50 cycles, and the adsorbent lost 6.9% of its initial adsorption capacity. Chen et al. [Reference: 64] impregnated HMS with PEI(600), and the capacity of the adsorbent decreased by 2% after 4 TSA cycles. The use of high molecular weight PEI in combination with low desorption temperatures is necessary to maintain thermal stability. Zhang et al. [Reference: 65] reported PEI(M nUsing ( = 25000), its capacity was maintained for 180 cycles by desorbing at 55 °C, but the capacity was 2.35 mmol / g in 10% CO₂, desorption continued for 15 minutes, and 100% regeneration was not achieved. For grafted adsorbents, the adsorption capacity is lower compared to impregnated ones, but the thermal stability is not a problem up to 120 °C [References: 17, 35, 41, 48, 66]. At this point, considering the trade-off between the CO₂ capacity and stability of the adsorbent, both classes, impregnated and grafted adsorbents, are limited to an average working capacity of 2.5 mmol / g in the dry state. From the perspective of chemical stability, it was found that primary amines have greater resistance to an oxygen atmosphere up to 90 °C than secondary and primary-secondary combinations [Reference: 67]. However, since the secondary amine-based adsorbent according to the embodiment functions better at 40 °C, the oxidative decomposition reaction is not a problem, and in particular, Heydari-Gorji et al. [Reference: 67] found that it is stable up to 70 °C. Regarding chemical stability in a CO₂-rich atmosphere, combinations of primary and primary-secondary amines show very poor resistance under the desorption conditions planned for the adsorbents developed especially by the present inventors (des: 100% CO₂ and t > 120 °C) [Reference: 36]. In this case, the secondary amine-based adsorbent is very stable even at a high temperature of 145 °C.

[0158] Calorimetry The isosteric heat of adsorption of the AS-3-0.9 adsorbent within the temperature interval of 40 - 100 °C is illustrated in Fig. 8a. It can be seen that when the temperature is increased from 40 to 100 °C, the heat of adsorption decreases from 98 to 31 kJ / mol. By averaging the initial isosteric heat at the adsorption points (low CO2 loading) for each temperature value and plotting it against the reciprocal of the absolute temperature, a linear relationship was obtained (Fig. 8b). Based on the fitted trend line, the heats of adsorption at 120, 134, and 140 °C were estimated. The heat of adsorption with a net zero was estimated and calculated at 134 °C. The decrease in the heat of adsorption is clearly in contrast to aqueous amine solvents, where increasing the temperature results in a larger heat of adsorption as observed by Arshad et al. [Reference: 68] and Kim et al. [Reference: 69], with heats of adsorption exceeding 150 kJ / mol CO2 being observed. The research of the present inventors shows a very important discovery that in the case of surface-fixed amine adsorbents (e.g., AS-3-0.9), only sensible heat is required and no extra energy (adsorption energy) is needed to reverse the amine-CO2 reaction. The significant difference in the temperature dependence of the heat of adsorption must be related to molecular movement with increasing temperature. Molecular movement in 3D involves translational, rotational, and vibrational movement. In the liquid phase, temperature changes do not result in significant changes in the degrees of freedom of CO2 molecules. When CO2 is adsorbed on a solid surface, some degree of freedom of movement is lost like translational movement, and the 3D molecule becomes a 2D or 1D molecule. With increasing temperature, the vibration frequency significantly increases in 2D or 1D molecules. These changes in freedom can be explained by entropy changes. To confirm these hypotheses, entropy changes were estimated based on the Langmuir adsorption isotherm. The equilibrium constant K was obtained by fitting the Langmuir type to the experimental adsorption isotherm at each temperature. The entropy change at a certain temperature was then estimated from K, and the heat of adsorption was measured (details can be found in the supplementary information). More significant changes in entropy change were discovered with increasing temperature. Based on statistical thermodynamics, the total entropy can be divided into contributions from translation, rotation, and vibration, and the electronic ground state. In this specification, the amine compound is fixed to the solid, and the freedom of the amine is relatively small and can be regarded as the solid surface.When CO2 binds to the amine group, the bond mostly returns to vibration, and exposing it to a higher temperature increases the frequency, thus weakening the bond between the amine group and CO2 and even breaking the bond without the need for extra energy. If the amine compound is in liquid form and the amine-CO2 bond vibration frequency can be compensated by rotational and translational movements, it does not weaken the bond between the amine and CO2. The decrease in the heat of desorption is explained by the entropy-induced enthalpy change. It clearly explains the advantage of high temperature such as 140 °C with pure CO2 in terms of the desorption energy compared to low-temperature vacuum desorption. Furthermore, it opens a new way to the rational design of solid adsorbents that reduce the heat of desorption. Overall, this discovery contributes to reducing the energy disadvantage related to amine-based solvent CO2 capture systems.

[0159] Discussion of Embodiments N-MAPTMS was grafted onto PE-MCM-41 produced by the inventors. The nitrogen content was adjusted by manipulating two synthesis variables: the N-MAPTMS / PE-MCM-41 (X, mL / g) and H2O / PE-MCM-41 (Y, mL / g) ratios. The adsorbents obtained at the amino-silane / silica and water / silica ratios of 3 and 0.9 mL / g had 5.25 amine groups / nm 2 of the optimal N surface density, respectively, and functioned best in terms of the CO2 adsorption capacity (1.94 mmol / g at 40 °C and 5% CO2 / N2) and efficiency (0.52 mol CO2 / mol N at 40 °C and 5% CO2 / N2). The large surface area and pore volume of PE-MCM-41 contributed to the formation and sufficient distribution of the 3D structure of the amino-silane inside the porous medium, enabling good diffusion of CO2 to the amine sites. The accelerated CO2 diffusion was seen from the immediate increase in weight when switching to a 5% CO2 / N2 flow, thus reaching 90% of the total capacity corresponding to 40 °C in less than 3 minutes. Furthermore, AS-3-0.9 showed CO2 good CO2 capacity at <5 kPa and P of 3, 1, and 0.03 kPa, respectively CO2And reached 1.88, 1.73, and 0.94 mmol CO2 / g at 40 °C, setting it far beyond most of the adsorbents in the literature (see Supplementary Table 2 in Figure 10). Another aspect carried out in this study was the thermal and chemical stability of AS-3-0.9. The adsorbent showed excellent thermochemical stability during 205 TSA cycles at 80% CO2 and 50 - 145 °C, indicating the presence of covalent bonding of aminosilane to the silica surface and showing no signs of urea species. The adsorbent further showed sufficient long-term stability in a gas mixture with a composition similar to flue gas from a natural gas power plant, which contains O2 and H2O in addition to CO2. The simple synthesis of the PE-MCM-41 silica support and the direct grafting of aminosilane on the silica surface without the need for amine modification different from PEI [Reference: 24], TEPA [Reference: 26] enables the method to be easily scaled up together with the high CO2 capacity of the adsorbent and flexible operating conditions. Furthermore, the adsorbent does not show heat of adsorption at a high temperature of 140 °C and thus requires only sensible heat for the desorption unit, resulting in a reduction in energy penalty.

[0160] Comparison with previous adsorbents Table 3 in Figure 11 shows the comparison between the adsorbent of the present invention (AS-3-0.9) and the pre-prepared adsorbents (Reference 1 corresponds to [Reference: 69], Reference 2 corresponds to [Reference: 48], Reference 3 corresponds to [Reference: 70], and Reference 4 corresponds to [Reference: 47]). The properties presented in the table include amine group density (calculated according to the method in this literature), amine group density (literature value), efficiency, and capacity. It is demonstrated that AS-3-0.9 has the highest amine group density, efficiency, and capacity among the adsorbents.

[0161] Methods and materials of the embodiments Hexadecyltrimethylammonium bromide (CTAB; ≥98%, MW = 364.45 g / mol, Sigma-Aldrich), ammonia solution (25%, AnalaR NORMAPUR™, WVR Chemicals), tetraethyl orthosilicate (TEOS; ≥99% (GC), MW = 208.33 g / mol, Sigma-Aldrich), and distilled water were used to synthesize PE-MCM-41. N-Methylaminopropyltrimethoxysilane (N-MAPTMS; 97% min, Gelest), toluene (≥99.5%, MERCK), and distilled water were used to covalently bond N-MAPTMS to the surface of PE-MCM-41. Ultra-high quality gases were purchased from Linde: N2 (5.0), CO2 (5.3), 0.1, 1, and 10% CO2 balance N2 (uncertainty ±2%), Ar (5.0), synthetic air (5.0, 21% O2). All chemicals and gases were used without prior purification.

[0162] Synthesis of PE-MCM-41 PE-MCM-41 was prepared according to the novel procedure described in [Reference: 45]. Briefly, PE-MCM-41 was synthesized at 25 °C using a stirring-heating plate. Vigorous mixing at 400 rpm was maintained throughout the entire procedure. In a typical synthesis, 4 g of CTAB, the structure-directing agent, was mixed with 240 mL of water in a 500 mL beaker. A stirring time of 30 minutes was allowed to ensure homogeneous dispersion of the surfactant. As a next step, 20 mL of TEOS was added dropwise (over 10 minutes) to the CTAB-water mixture and then mixed for 5 minutes. Subsequently, 2 mL of 25% ammonia solution, the mineralizing agent, was finally added to catalyze the hydrolysis and condensation of TEOS. After the addition of the ammonia solution, the mixture started to form a gel and was kept under the same conditions for 19 hours. The beaker was covered with a parafilm layer to prevent loss of ammonia water throughout the sol-gel transition reaction. The white solid product was repeatedly filtered, washed with a large amount of distilled water, and then dried at room temperature overnight in a well-ventilated area. The surfactant was removed by calcination in a static air atmosphere using a muffle furnace. First, the solid was dried at 150 °C for 2 hours to completely remove water, then heated to 550 °C at a heating rate of 1 °C / min and maintained at that temperature for 5 hours. After cooling, the mesostructured product was stored in a glass vial with a lid and placed inside a glass desiccator jar whose bottom volume was filled with silica gel beads as a desiccant material. This was done to keep the calcined PE-MCM-41 away from moisture.

[0163] Grafting of N-MAPTMS onto the PE-MCM-41 of the Embodiment N-MAPTMS was covalently bonded to the surface of PE-MCM-41 according to the wet grafting approach reported by [References: 19, 35, 66]. A silica amount in the range of 0.36 - 0.38 g was loaded into a 100 mL Erlenmeyer flask, and then 50 mL of toluene was added. A specific amount of water was added dropwise while vigorously mixing at 25 °C (400 rpm). The solution was stirred for 3 hours to allow the water to penetrate the porous structure of the silica. Subsequently, a volume of N-MAPTMS was added dropwise to the mixture, and the flask was immersed in an oil bath and rapidly heated to 85 °C. The suspension was stirred and kept under reflux for 12 hours. The N-MAPTMS-grafted PE-MCM-41 was repeatedly vacuum filtered and washed with aliquots of toluene, and then dried at 50 °C for 6 hours. The dried product was stored in a glass vial with a lid. The prepared samples were labeled as AS-X-Y, where AS denotes the amino-grafted silica sample, followed by the amino silane (mL) / silica (g) ratio as X and the water (mL) / silica ratio (g) as Y.

[0164] Material properties of the embodiment N2 physisorption of the embodiment The N2 adsorption-desorption isotherms were measured at -196 °C using a Micromeritics TriStar3000 apparatus. Prior to adsorption, the PE-MCM-41 and AS-X-Y samples were degassed overnight under vacuum in a VacPrep061 Degasser at 200 and 80 °C, respectively. The temperature of 80 °C was selected for the grafted samples to minimize amine decomposition. The specific surface area was calculated using the BET (Brunauer-Emmett-Teller) model in the relative pressure range of 0.05 - 0.3. The pore size distribution was calculated using the BJH (Barrett-Joyner-Halenda) approach. Complete surface saturation was assumed to be at a relative pressure (P / P0) of 0.97, which was considered for the estimation of the total pore volume.

[0165] XRD of the embodiment The X-ray diffraction (XRD) patterns of the MCM-41 and AS-X-Y samples were measured on a Bruker D8 Focus operating under CuKα radiation (1.54 Å) at 40 kV and 40 mA. Diffraction patterns were obtained in the 2θ range of 1.5 - 10° with a step size of 0.02° and a step time of 6 seconds. A divergence slit with an aperture of 0.1 mm was used.

[0166] TGA of the embodiment The amount of N-MAPTMS on the AS-X-Y sample was quantified by thermogravimetric analysis (TGA) on a TA-Q500 instrument. The temperature gas-profile involved two steps: (i) sample pretreatment under a N2 flow at 150 °C for 1 hour to remove moisture, and (ii) heating ramp of 5 °C / min to 800 °C in a Doell with N2 containing 14.7 vol% O2 for 1 hour to remove the organic content. Using the weight loss obtained in step (ii), the grafting amount of the aminosilane was calculated by assuming monodentate coordination of the methoxy groups and other aminosilanes with the effective hydroxyl groups on the silica surface. Considering this, the mmol of N was simply determined to be 83 g / mol by dividing the weight loss. The weight loss of PE-MCM-41 was also determined with the same temperature-gas profile.

[0167] CO2 adsorption-desorption experiment of the embodiment The CO2 capacity of all samples was measured by thermogravimetric analysis (TGA) on a TA-Q500 instrument using N2(5.0) as the balance purge gas. A 10% CO2 balance N2 gas was used as the sample purge gas, and the total gas flow was maintained at 100 mL / min. Approximately 10 mg of sample was used for all measurements. Before exposing the sample to the CO2-N2 mixture, the AS-X-Y samples were activated by performing a degassing step under N2 flow at 120 °C for 1 hour to remove adsorbed species (e.g., CO2, H2O, trace amounts of solvent). The temperature profile then followed a cooling step to the desired temperature, switched to a 5% CO2 balance N2 mixture, and the mixture was maintained for 1 hour. The CO2 adsorption step was performed at 100 °C for 10 minutes under N2 flow between desorption steps and was carried out at 40 and 50 °C. The isotherms of the AS-3-0.9 sample were recorded at 40, 50, and 60 °C within a pressure range of 0.02 - 80 kPa using the same instrument. For this purpose, 0.1, 1, and 10% CO2 balance N2 and / or He gas blends were used. Each point of the isotherm was measured for 1 hour.

[0168] Multi-cycle stability of the embodiment Dry adsorption-desorption of the embodiment The stability of the AS-3-0.9 sample was examined using a TGA-TA-Q500 instrument with a dry 80% CO2 balance N2 flow. 205 (423 hours) adsorption-desorption cycles were performed at adsorption-desorption temperatures of 50 and 145 °C, respectively, under a total flow rate of 100 mL / min. When cooling to the adsorption temperature, the gas was switched from CO2 to N2 to completely remove CO2 and accurately quantify the adsorption capacity of the next cycle.

[0169] Simulated flue gas of the embodiment The stability of the AS-3-0.9 sample was also investigated at 50 °C for 20 min with simulated flue gas as the adsorbed gas mixture (5% CO2, 10.5% O2, 3% H2O balanced with N2 and Ar), and at 140 °C for 25 min with 77% CO2 and 4% H2O (in Ar) as the desorbed gas. 413 and 272 mL / min were the total flow rates for adsorption and desorption, respectively. The cooling step was carried out under pure Ar. The switching from CO2 to Ar was also necessary to completely remove the adsorbed CO2. A glass gas scrubber was used at 35 °C to allow the passage of the wet gas over the sample. A constant temperature was maintained in a water bath (Julabo12). The main part of the gas scrubber was heated to 50 - 70 °C to avoid water condensation. A similar stability test was carried out by replacing the desorbed gas mixture with a flow of 200 mL / min of pure Ar (dry desorption). 99 cycles (366 h) were performed in both cases.

[0170] Temperature-programmed desorption (TPD) analysis in the dry and wet states was performed on a TGA-Linseis coupled to an MS detector. 0.1, 1% CO2 balanced with N2-He and pure N2 gas were used for MS calibration. The calibration curve was generated based on the linear relationship between the CO2 concentration and the MS signal corresponding to 44 atomic mass units. For this purpose, 9 CO2 concentrations were used to determine the coefficient of determination R 2It becomes 0.9986. All the analyses were carried out on the AS-3-0.9 sample. Each test was performed according to the following steps: (i) Pretreatment at 120 °C for 30 minutes under Ar at 200 mL / min, (ii) Cooling to the desired temperature (40, 50 °C) at a cooling rate of 1 °C / min in Ar at 200 mL / min, (iii) Switching to 1% CO2 with or without water and maintaining for 2 hours to reach equilibrium, (iv) Switching to Ar for 4 minutes to purge the TGA-MS path, (v) Heating to 120 °C at a ramp of 5 °C / min in Ar at 100 mL / min to release the adsorbed CO2. The CO2 released from the adsorbent was quantified based on the MS signal area and the calibration curve. The adsorption step was realized at 40 and 50 °C. At 40 °C, two TPD tests were carried out in 2.3% and 3% H2O respectively, and further at 50 °C in 3% H2O. Water was introduced into the sample-containing chamber described in the simulated flue gas section. Blank tests were realized for each type of analysis to correct the MS baseline.

[0171] Embodiments include many variations and modifications to the above process.

[0172] Embodiments include secondary monoamines grafted onto silica supports as described in ‘CO2-Induced Degradation of Amine-Containing Adsorbents: Reaction Products and Pathways’; Abdelhamid Sayari, Aliakbar Heydari-Gorji, and Yong Yang; Journal of the American Chemical Society; 2012, 134, pages 13834 to 13842, the entire content of which is incorporated herein by reference.

[0173] All of the components of the reactor system of the embodiments are scalable so that the implementation of the embodiments is suitable for small, medium, and large industrial-scale processes.

[0174] The flowcharts and their descriptions in this specification should not be understood to define a fixed order for performing the method steps described herein. Rather, the method steps can be performed in any executable order. Although the present invention has been described with respect to specific exemplary embodiments, it should be understood that various modifications, substitutions, and changes can be made to the disclosed embodiments without departing from the essence and scope of the invention described in the appended claims and which would be apparent to those skilled in the art.

[0175] Throughout this document, references are made to the following documents, all of which are hereby incorporated by reference into this specification.

[0176]

Table A1

[0177]

Table A2

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Table A3

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Table A4

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Table A5

[0181]

Table A6

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Table A7

[0183]

Table A8

Claims

1. A solid adsorbent for carbon dioxide capture processes, The adsorbent, A solid adsorbent carrier containing pores, and The solid adsorbent carrier contains a secondary amine covalently bonded to it, wherein the secondary amine is confined within the pores of the solid adsorbent carrier, with 4 amine groups / nm ２ A solid adsorbent that exists at a density exceeding [a certain value].

2. The solid adsorbent according to claim 1, wherein the solid adsorbent carrier is a silica adsorbent carrier.

3. The solid adsorbent according to claim 2, wherein the silica adsorbent carrier is a porous foamed mesoporous silica adsorbent carrier, and preferably PE-MCM-41.

4. The secondary amine covalently bonded to the solid adsorbent carrier has the structure of formula (I): 【Chemistry 1】 (In the formula, * indicates a bond point to an atom (preferably Si) that is covalently bonded to or forms part of the solid adsorbent support. n is between 1 and 6. p is between 0 and 5. A solid adsorbent according to claim 1, having the following characteristics.

5. The secondary amine covalently bonded to the solid adsorbent carrier has the structure of formula (I'): 【Chemistry 2】 (In the formula, * indicates a bond point to an atom (preferably Si) that is covalently bonded to or forms part of the solid adsorbent support. A solid adsorbent according to claim 4, having the following characteristics.

6. The aforementioned secondary amine has 4.5 amine groups / nm ２ More than 5 amine groups / nm ２ The solid adsorbent according to claim 1, which exists at a density exceeding a certain level.

7. The solid adsorbent carrier is a silica adsorbent carrier which is a porous foamed MCM-41. The secondary amine covalently bonded to the solid adsorbent carrier has the structure of formula (I'): 【Transformation 3】 (In the formula, * indicates a bond point to an atom (preferably Si) that is covalently bonded to or forms part of the solid adsorbent support. It has, The secondary amine is trapped inside the pores of the solid adsorbent carrier, with 5 amine groups / nm ２ Exceeding 6 amine groups / nm ２ The solid adsorbent according to claim 1, which exists at a density less than [amount missing].

8. The secondary amine has a ΔV / V ratio of 0.7 to 1.1, preferably 0.85 to 1.1, and more preferably 0.9 to 1.05 for the solid adsorbent. アミノグラフト化 The solid adsorbent according to claim 1, wherein the solid adsorbent is confined within the pores of the solid adsorbent in such a ratio.

9. A method for preparing a solid adsorbent for a carbon dioxide capture process, The adsorbent, A solid adsorbent carrier containing pores, and The solid adsorbent carrier contains a secondary amine that is covalently bonded to the solid adsorbent carrier and trapped inside the pores of the solid adsorbent carrier. The aforementioned method, A solid adsorbent carrier containing pores (a) A compound comprising a secondary amine group and a group capable of forming a covalent bond with the solid adsorbent carrier, and (b) including the step of bringing into contact with water, The compound is present in an amount of 2 to 6 mL per gram of solid adsorbent carrier. The method is characterized in that the water is present in an amount of 0.5 to 1.5 mL per gram of solid adsorbent carrier.

10. The method according to claim 9, wherein the solid adsorbent carrier is a silica adsorbent carrier.

11. The method according to claim 10, wherein the silica adsorbent carrier is a porous foamed mesoporous silica adsorbent carrier, and preferably PE-MCM-41.

12. The aforementioned solid adsorbent carrier is (d) Approximately 700 to approximately 1100m ２ / g surface area, and / or (e) Approximately 1.2 to approximately 2.0 cm ３ Pore ​​volume per g, and / or (f) The method according to claim 9, having an average pore size of about 5 to about 10 nm.

13. The aforementioned compound has formula (II): 【Chemistry 4】 (In the formula, X is each independently a detachable group, preferably, each X is independently C １ -C ６ an alkoxy group, n is between 1 and 6. p is between 0 and 5. The method according to claim 9, wherein the aminosilane is...

14. The method according to claim 13, wherein the aminosilane is N-methylaminopropyltrimethoxysilane.

15. The aforementioned contact step is carried out in the presence of toluene. The toluene is present in an amount of 140 to 417 mL per gram of solid adsorbent carrier. (a) The compound is present in an amount of 2.0 to 2.4 mL of the solid adsorbent carrier, and the water is present in an amount of 0.6 to 0.9 mL of the solid adsorbent carrier, or (b) The method according to claim 9, wherein the compound is present in an amount of 2.5 to 5 mL of the compound per gram of the solid adsorbent carrier, and the water is present in an amount of 0.7 to 1.3 mL of water per gram of the solid adsorbent carrier.

16. The compound is present in an amount of approximately 3 mL per gram of solid adsorbent carrier. The water is present in an amount of approximately 0.9 mL per gram of solid adsorbent carrier. The method according to claim 15, wherein the toluene is present in an amount of about 140 mL of toluene per gram of solid adsorbent carrier.

17. The solid adsorbent carrier is a solid silica adsorbent carrier which is a porous foamed MCM-41. The compound is N-methylaminopropyltrimethoxysilane, The aforementioned contact step is carried out in the presence of toluene. The toluene is present in an amount of 140 to 417 mL per gram of solid adsorbent carrier. (a) The compound is present in an amount of 2.0 to 2.4 mL of the solid adsorbent carrier, and the water is present in an amount of 0.6 to 0.9 mL of the solid adsorbent carrier, or (b) The method according to claim 9, wherein the compound is present in an amount of 2.5 to 5 mL of the compound per gram of the solid adsorbent carrier, and the water is present in an amount of 0.7 to 1.3 mL of water per gram of the solid adsorbent carrier.

18. In the contact step, the secondary amine is subjected to a ΔV / V ratio of 0.7 to 1.1, preferably 0.85 to 1.1, and more preferably 0.9 to 1.05 for the solid adsorbent. アミノグラフト化 The method according to claim 9, wherein the solid adsorbent is confined within the pores of the solid adsorbent in such a ratio.

19. A solid adsorbent for a carbon dioxide recovery process, wherein the adsorbent is A solid adsorbent carrier containing pores, and The solid adsorbent carrier contains a secondary amine that is covalently bonded to the solid adsorbent carrier and trapped inside the pores of the solid adsorbent carrier. The solid adsorbent is a solid adsorbent that can be obtained by the method described in claim 9.

20. The aforementioned solid adsorbent is (a) Approximately 20 to approximately 80m ２ / g surface area, and / or (b) Approximately 0.15 to approximately 0.6cm ３ Pore ​​volume per g, and / or (c) The solid adsorbent according to claim 1 or claim 19, having an average pore size of about 26 to about 33 nm.

21. The solid adsorbent according to claim 1 or claim 19, wherein the adsorbent is for use in a fixed adsorbent bed or a mobile adsorbent bed.

22. The solid adsorbent according to claim 1 or claim 19, wherein the adsorbent is intended for use in pellet form or powder form.

23. A method for regenerating solid adsorbents for carbon dioxide capture processes, A solid adsorbent containing carbon dioxide is heated to a temperature of 120 to 150°C to release the carbon dioxide contained in the solid adsorbent. The method wherein the solid adsorbent is the solid adsorbent described in claim 1 or claim 19.

24. The use of solid adsorbents in carbon dioxide adsorption, The adsorption of carbon dioxide is carried out at a temperature of less than 100°C. The solid adsorbent is the solid adsorbent described in claim 1 or claim 19.

25. Use of a solid adsorbent in a carbon dioxide recovery process that uses thermal swing adsorption as a desorption strategy for carbon dioxide purging, wherein the solid adsorbent is the solid adsorbent described in claim 1 or claim 19.

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