CO2 Sorption Capacity Research Articles

Improved CO2 Sorption Performance of Calcium Oxide (CaO) Sorbent with Nickel Oxide Additive

Currently, carbon capture and storage (CCS) technology appeared to be the most viable method to reduce carbon dioxide (CO2) emission from its existing sources. This paper reports the improved performance of calcium oxide (CaO)-based sorbents with the addition of nickel oxide (NiO) as an additive (denoted as CaO:NiO) in CO2 sorption process (CaO carbonation reaction). Pure CaO was used as benchmarked sorbent in this study. The samples were synthesized using the sol-gel method and CaO:NiO were evaluated for their performance in CaO carbonation at different sorption temperatures, from its CO2 sorption capacity, CO2 sorption rate, and kinetic performance. CaO:NiO has demonstrated an excellent CO2 sorption capacity of 0.79 mmol CO2/mmol CaO, meanwhile pure CaO exhibited lower CO2 sorption capacity of 0.61 mmol CO2/mmol CaO at 600 °C. During the chemical reaction controlled stage, the CO2 sorption rate of CaO:NiO was 0.78 mmol CO2/mmol CaO.min at 600 °C compared to pure CaO with sorption rate of 0.18 mmol CO2/mmol CaO.min. This study indicates that the addition of nickel oxide has successfully improved the CO2 sorption rate and capacity of CaO for CaO:NiO. Based on the kinetic study, it has been observed that the diffusion controlled stage has a greater resistance towards the CO2 sorption process (carbonation reaction) compared to rapid chemical reaction controlled stage. Experimental carbonation data for CaO:NiO fitted very well to the shrinking core model (SCM) with high correlation coefficient (R2 >0.936). The specific rate constants of rapid chemical reaction and diffusion-limited stages are directly proportional to the carbonation temperature. The activation energy required for CaO:NiO sorbent during the chemical reaction control stage was 31.81 kJ/mol.

One-step synthesis of spherical CaO pellets via novel graphite-casting method for cyclic CO2 capture

Granulation of CaO sorbents is the prerequisite for the practical application of the calcium looping system for CO2 capture at high temperatures. This work, for the first time, proposed a simple and facile graphite-casting granulation technique to achieve the one-step pelletization of CaO-based sorbent pellets. The as-prepared pellets exhibited good sphericity and a uniform diameter distribution of 2.5–3 mm. It was found that the granulation process caused the densification of the microstructures for the sorbent, thus decreasing the surface areas and CO2 sorption performance. Hence, a porosity promoter was employed to modify the pellets, endowing the granulated sorbents with enhanced porous structures. As a result, the CO2 sorption capacity of the modified pellets was increased by 48% compared to that of the unmodified pellets over 20 sorption/desorption cycles. In addition, the cyclic performance of the pellets under 50% CO2 desorption atmospheres was also evaluated. The results showed that the presence of CO2 at the desorption stage aggravated the sintering and, thus, decreased the sorption capacity of the pellets. Nevertheless, the pellets modified by the porosity promoter still performed much better than the unmodified ones. The graphite-casting CaO pellets exhibited good mechanical properties, including compression strengths and attrition resistance, which were quite important for the practical application of CaO sorbents in circulating fluidized bed. Good chemicophysical performance demonstrates that the graphite-casting granulation technique is applicable to the preparation of CaO pellets.

Experimental investigation of improved calcium-based CO2 sorbent and Co3O4/SiO2 oxygen carrier for clean production of hydrogen in sorption-enhanced chemical looping reforming

In this study, highly pure hydrogen is produced in sorption enhanced chemical looping steam methane reforming (SE-CLSMR) using cobalt-based oxygen carrier (OC) and cerium promoted CaO-based sorbent. In addition, the CO2 removal from a gas stream at high temperatures is investigated via calcium looping process prior to SE-CLSMR process. The prepared samples are characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) and energy dispersive X-ray spectroscopy (EDX) techniques. The effect of Ca/Ce molar ratio (100/0.00–0.91/0.09), sorption temperature (550–650 °C) and sorbent lifetime are studied to find the optimal sorbent. The characterization results show the uniform and orderly CeO2 dispersed sorbent nanoparticles that notably improved the sorbent morphology compared with blank CaO. The sorption results revealed the negative effect of temperature on CO2 uptake of all the samples. In addition, the CO2 sorption evaluations indicate that the molar ratio of cerium to calcium plays a significant role in the stability of sorbent and improved the CO2 sorption capacity significantly. The high CO2 removal efficiency in the cerium modified sorbents could be due to decrease in diffusion resistance of CO2 through the sorbent structure during the carbonation reaction. Furthermore, results show that the addition of cerium to the sorbent structure, effectively improves the thermal resistance of synthesis sorbents. The SE-CLSMR results showed that the H2 purity could be increased up to about 95% considering Co3O4/SiO2 oxygen carrier and cerium promoted calcium-based sorbent at relatively low temperature of 550 °C, which is comparable with 84% in CLR process.

Shaping metal\u2013organic framework (MOF) powder materials for CO2 capture applications\u2014a thermogravimetric study

The paper presents the effect of the tabletting pressure and time on the chemical structure and crystallinity of the CuBTC and MIL-53(Al) metal–organic framework tablets. For MOFs, the no-binder tabletting method was employed using a pressure of 3.7, 7.4, 29.6 and 59.2 kN m−2, respectively, for a duration of 0.5, 1 and 2 min. The obtained tablets were crushed and sieved to obtain the desired fraction from 500 to 650 µm. In this study, the thermogravimetric test has been used for the assessment of the effect of shaping metal–organic frameworks on the CO2 adsorption properties. The examination of the CO2 sorption capacity of metal–organic frameworks was carried out using a Mettler TGA/SDTA 851e thermobalance and TG-Vacuum. The results indicate a significant effect of compression on the crystal structure and CO2 sorption capacity of MOFs.

Highly efficient and durable metal-organic framework material derived Ca-based solid sorbents for CO2 capture

Calcium looping is a promising technology for CO2 capture, although traditional calcium-based sorbents undergo a rapid loss of capacity after repeated cycles. Improving the toughness of sorbents can be accomplished with the use of stabilizer compounds, but at the cost of sorption performance. Minimizing the stabilizer content whilst maintaining high thermal stability is an effective pathway to solve this bottleneck. Here, a facile MOF-templated synthesis route is for the first time reported to yield highly efficient Al2O3-stabilized, Ca-based sorbents. Cyclic performance experiments and detailed characterization techniques are employed to identify the effects of synthesis factors on the structure-performance relationship of the synthesized CO2 sorbents. Calcium aluminum solid solution and its homogeneous mixture with CaO at the nanoscale provide for high thermal stability. The different CO2 uptake behavior for the synthesized sorbents primarily results from the influence of synthesis factors on the crystallization rates and coordination modes between metal ion and organic ligands. The stabilizer content (i.e. Al2O3) can be as low as 4.44 wt% and yet maintain a favorable thermal stability. Compared to that of the limestone-derived CO2 sorbents, the best MOF-derived sorbent can achieve about 500% times the CO2 sorption capacity after 30 repeated CO2 uptakes and sorbent regenerations.

Liquid marble-derived solid-liquid hybrid superparticles for CO2 capture

The design of effective CO2 capture materials is an ongoing challenge. Here we report a concept to overcome current limitations associated with both liquid and solid CO2 capture materials by exploiting a solid-liquid hybrid superparticle (SLHSP). The fabrication of SLHSP involves assembly of hydrophobic silica nanoparticles on the liquid marble surface, and co-assembly of hydrophilic silica nanoparticles and tetraethylenepentamine within the interior of the liquid marble. The strong interfacial adsorption force and the strong interactions between amine and silica are identified to be key elements for high robustness. The developed SLHSPs exhibit excellent CO2 sorption capacity, high sorption rate, long-term stability and reduced amine loss in industrially preferred fixed bed setups. The outstanding performances are attributed to the unique structure which hierarchically organizes the liquid and solid at microscales.

2D/3D amine functionalised sorbents containing graphene silica aerogel and mesoporous silica with improved CO2 sorption

This work investigates the performance of amine functionalised 2D/3D sorbents for CO2 capture. The 2D/3D structures were based on a combination of flake-like reduced graphene-silica oxide (G-Si) aerogel and rod-like mesoporous silica SBA-15. The G-Si aerogel formed mainly silica microporous structures which enveloped graphene sheets. The SBA-15 displayed the classical rod-like mesoporous features with high pore volume. The addition of G-Si aerogel to SBA-15 for the amine functionalised samples significantly reduced the combined total surface area and pore volume. Interestingly, the CO2 sorption capacity increased and peaked for samples containing G-Si aerogel/SBA-15 at 1:20 mass ratio (4.7 wt%), though declining thereafter. This counterintuitive effect of increasing CO2 sorption capacity but decreasing surface area and pore volume was attributed to the special morphological features of the 2D/3D sorbent assembly. At these optimal conditions, the flake-like G-Si aerogel was well intercalated with the rod-like SBA-15. As a result, the inter-particle space formed between the flake-like and rod-like assembly accommodated TEPA which facilitate the mass transfer and reaction between the amine groups and CO2. These special 2D/3D morphological features delivered high CO2 sorption capacity of 6.02 mmol g−1. The 2D/3D sorbents were also very stable under sorption and desorption cycles whilst heat of sorption were up to 22% lower than the analogue 3D SBA-15/TEPA sorbent.

Performance and operating limits of a sorbent-catalyst system for sorption-enhanced reforming (SER) in a fluidized bed reactor

The combined performance of a synthetic CaO-Ca12Al14O33 sorbent and an Ni-MgAl2O4 reforming catalyst was tested in a fluidized bed reactor under relevant operating conditions for the sorption-enhanced reforming (SER) process. The effect of CH4 space velocity (i.e. kgCH4/h·kgcat), steam-to-carbon (S/C) ratio and superficial gas velocity on product gas composition was assessed, as well as the effect of regeneration conditions on material performance. Moreover, a bi-functional material prepared by mechanical mixing of the separate materials was also tested in the reactor under consecutive SER/regeneration cycles. H2 contents as high as 96 vol% (N2 free, dry basis) were achieved under SER operation, using the separate materials working with an Ni content of 3.75 wt% in the solid bed at 650 °C with S/C ratios of 3 and 4. This solid system is able to process up to 0.63 kgCH4/h·kgcat at 0.1 m/s superficial gas velocity and with an S/C ratio of 4, although the CH4 input has to be reduced to 0.33 kgCH4/h·kgcat when working with a lower S/C ratio. Similar H2 contents to those found with the separate materials were obtained with the combined sorbent-catalyst material working with 0.33 kgCH4/h·kgcat at 0.1 m/s superficial gas velocity and S/C ratios of 3 and 4. The CO2 sorption capacity of the combined material produced the same as that of the separate sorbent particles (i.e. around 0.25 gCO2/g calcined sorbent), while remaining stable throughout the SER/regeneration cycles.

Fabrication of ultramicroporous triphenylamine-based polyaminal networks for low-pressure carbon dioxide capture

Three triphenylamine-based polyaminal networks (TMPs) with monodispersed ultramicropore (about 0.54 nm) and abundant doped-nitrogen (up to 42.88 wt%) are successfully prepared through the direct polycondensation of triphenylamine-based aldehydes with melamine. The synergistic effects of uniform ultramicropore and rich CO2-philic polar sites endow TMPs with exceptional CO2 sorption capacity and selectivity over N2 and CH4. For example, the CO2 uptakes of TMPs can reach 15.7 wt% (273 K) and 11.2 wt% (298 K) at 1 bar. Especially, at a low pressure of 0.15 bar, TMP-3 simultaneously exhibits excellent CO2 sorption capacity of 4.16 wt% (∼1 mmol g−1, 298 K), high adsorption selectivities of CO2/N2 (61.9, 298 K) and CO2/CH4 (7.8, 298 K) and good cycle reusability, which are superior to most of the microporous polymers. In addition, the porous properties of TMPs could be effectively tuned by varying the amount of substitution formyl. This facile preparation method and excellent CO2 adsorption properties enable TMPs to possess promising application potential in CO2 capture and separation from low-concentration gas mixtures.

CO2 Sorption Capacity in Clay-Rich Shales with Moisture Content

Injected CO2 in geological sites may contact the impermeable caprock/shales overlying the injection reservoirs. In such cases, the shales may provide additional storage capacity due to CO2 adsorption in the microstructures. Shales have heterogenous mineral compositions and nano-scale microstructures (pore width < 200 nm), which result in complex wetting properties and low permeability. In such nanoporous materials, a large percentage of gas in place is stored by adsorption to the high surface areas. The complex mineralogy of shales, such as clay, quartz, carbonate and organic matter, will control sorption properties in addition to environmental pressure and temperature effects. The goal of this study is to determine the mineralogy and moisture effect on CO2 accessible surface area using subcritical adsorption and low pressure adsorption. Our results indicate that the total organic content (TOC) is a controlling factor of micropore volume in shale. We find a positive correlation where the excess micropore volume increases with increasing TOC of the shale. The hydrophobic nature of organic matter (OM) shows preferential adsorption when tested with different fluids such as nitrogen, hexane and water. With the micropore volume estimated from CO2 subcritical adsorption, CO2 storage potential in Utica shale is estimated to be double of previous theoretical estimation by Godec et al (2014). Moisture effect on shale and zeolites is studied to image the effect of irreducible water saturation, where the CO2 adsorption is significantly reduced with the presence of moisture.

Sorption-enhanced CO capture over Cu-Mn-Ce composite oxides with LiOH addition: CO oxidation and in-situ CO2 sorption

CuO-MnOx-CeO2 composite catalysts coupled with different amounts of LiOH sorbent were prepared using a solid-state impregnation method and characterized by XRD, N2 adsorption, FE-SEM/EDS and ICP-OES. Then the samples were tested dynamically and isothermally for CO capture involving CO oxidation and CO2 sorption reactions in the temperature range of 30–180 °C under the dry and wet conditions. The results showed that the samples were able to catalytically oxidize CO and chemically absorb CO2 in situ at low temperature. Particularly, CuMnCe/10LiOH exhibited the higher CO oxidation activity than the traditional CuO-MnOx-CeO2 catalyst, and significantly the resistance to water vapor of the sample was also promoted. Isothermal CO2 capture experiment results further revealed that CuMnCe/LiOH could achieve the larger CO2 sorption efficiency by the in-situ way when compared with trapping CO2 diluted in the feed gas. The promoted CO catalytic performance with the excellent tolerance to water poison, and the higher CO2 sorption capacity and efficiency, could be attributed to the synergistic interaction between the CO catalyst and the CO2/H2O sorbent induced by the sorption and transfer of the intermediate gases CO2 and H2O, which modified the influences of two-sidedness CO2 and H2O gases on CO oxidation and CO2 sorption reactions, respectively. These were summarized as a novel concept called Sorption-Enhanced CO Capture (SECC).

The Impact of Synthesis Method on the Properties and CO2 Sorption Capacity of UiO-66(Ce)

A series of cerium-based UiO-66 was obtained via hydrothermal and sonochemical methods, using the same quantities of reagents (cerium ammonium nitrate (CAN), terephthalic acid (H2BDC)) and solvents) in each synthesis. The impact of synthesis method and metal to linker ratio on the structural and textural properties of obtained UiO-66(Ce), as well as their composition in terms of Ce4+/Ce3+ ratio, structure defects resulting from missing linker, and CO2 adsorption capacity was discussed. By using typical characterization techniques and methods, such as XRD, N2 and CO2 sorption, TGA, XPS, and SEM, it was shown that the agitation of reacting mixture during synthesis (caused by stirring or ultrasounds) allows to obtain structures that have more developed surfaces and fewer linker defects than when MOF was obtained in static conditions. The specific surface area was found to be of minor importance in the context of CO2 adsorption than the contribution of Ce3+ ions that were associated with the concentration of linker defects.

Enhanced CO2 sorption capacity of amine-tethered fly ash residues derived from co-firing of coal and biomass blends

Co-firing of coal and biomass blends provides a promising route for clean energy utilization with high efficiency and mitigated pollutants emission. However, the technology meets an important challenge in effective utilization of the co-firing fly ashes. Efforts have been made to valorize the co-firing fly ash residues as potential CO2 sorbents. To achieve enhanced CO2 sorption performance, the samples were modified with tetraethylenepentamine (TEPA). Effects of amine loading, CO2 sorption temperature, initial CO2 concentration and gas flow rate on CO2 sorption behaviors of the amine-tethered sorbents were investigated. The desired sorbent with 25% TEPA loading presented the highest CO2 sorption capacity of 1.19 mmol CO2/g when tested under 60 °C and 15%CO2 with a total gas flow rate of 1200 ml min−1. The effects of regeneration temperature and ramping rate on sorbent regeneration performance were demonstrated. The maximum sorbent regeneration efficiency of 97.2% was achieved under the regeneration condition of 110 °C and 5 °C min−1. CO2 sorption capacity of the amine-tethered sorbent kept stable within 5 repeated cycles. These findings indicate that the amine-tethered sorbent could be a good candidate for on-site CO2 capture from flue gas in co-firing power plants.

CO2 and CH4 sorption properties of granular coal briquettes under in situ states

The aim of this work was an experimental research into the sorption properties of coal briquettes under the various states of stress. The present state of knowledge when it comes to the impact of stress on the CO2 and CH4 sorption properties of coal is limited. Hence, in situ sorption capacity or sorption-induced deformation may vary considerably from these specified in the unloaded conditions. As part of this paper, a research device that enables the sorption measurements for coal samples submitted to loads of up to 40 MPa is presented. Sorption experiments with pure CO2 and pure CH4 were carried out by means of the volumetric method, under isobaric-isothermal conditions. Dry coal material in the form of granular coal briquettes was used. Presented results aimed to prove the existence of a relation between the stress state, sorption capacity and volumetric deformation of coal. Gas sorption and desorption processes on coal may be triggered by the action of mechanical factor. The mechanical load applied to the coal sorbent reduces its sorption capacity but has no direct effect on swelling. The sorption or desorption induced volumetric changes of coal occur regardless of the stress state and regardless of the mechanism of the sorption process itself. Deeper coal seams with reduced CO2 and CH4 sorption capacity may not be as useful for ECBM techniques as the shallower coal seams. Reduction of the sorption capacity with depth may also explain the growing threat of coal and methane outbursts in the USCB mines observed in recent years.

Effect of interlayer anion on the CO2 capture capacity of hydrotalcite-based sorbents

A series of hydrotalcites (HTCs) samples with different compensating anions was prepared (several anions never used before). The physicochemical characterization of these materials was realized through several techniques (including XRD and SEM/EDS). The CO2 sorption capacities of the HTCs were assessed using a magnetic suspension balance (static tests) and CO2 breakthrough runs in a packed column (dynamic tests). The HTC-CO3 sample presents the highest CO2 sorption capacity (1.05 mmol·g−1, @ pCO2 = 1 bar and 300 °C) in comparison with the other materials. The sorption kinetics were analyzed from CO2 uptake measurements and two distinct contributions were observed. Besides, the effect of temperature on the CO2 sorption capacity was studied for HTC-CO3. The efficiency of the column (in the breakthrough tests) was higher for the HTC-CO3 formulation (20%).

Metal precursor impregnation sequence effect on the structure and performance of Ni[sbnd]Co/MgO catalyst

The influence of metal precursor impregnation sequence has been analyzed in terms of catalytic activity and stability of NiCo/MgO catalysts for coke oven gas reforming of carbon dioxide. It is found that the metal precursor impregnation sequence overwhelmingly affected the interaction among Ni, Co and MgO and resulted in different CO2 sorption capacity. Compared to the catalysts prepared by first Ni precursor impregnation (Co/Ni/MgO) or by simultaneous Ni and Co precursor impregnation (NiCo/MgO), the catalysts prepared by first Co precursor impregnation (Ni/Co/MgO) obtained a stronger interaction among Ni, Co and MgO, leading to strong CO2 adsorption, smaller Ni particle size (9.6 nm), higher metal dispersion (10.6%), lower carbon deposition (1.5 wt%) and finally resulted in a superior catalytic activity and stability for coke oven gas reforming of carbon dioxide (CH4 and CO2 conversion were 55 ± 1% and 80 ± 2%, respectively). We also proposed a model for the effect of metal precursor impregnation sequence on the particle distribution of Ni and Co in NiCo/MgO catalyst.

DEVELOPMENT OF INEXPENSIVE CELLULOSE-BASED SORBENTS FOR CARBON DIOXIDE

ABSTRACT Aqueous amine solutions are benchmark solvents for CO2 capture and their operational drawbacks are well-known. In order to overcome these problems, the support of amines on solid materials appears as an option for CO2 capture. Cellulose is a versatile and low-cost material that can be used as a support. This study reports chemical modification of cellulose fibers extracted from rice husk with different amines and their potential for CO2 capture. The obtained compounds were characterized by different techniques. The CO2 sorption capacity was gravimetrically assessed in a Magnetic Suspension Balance. Quantum mechanical simulations and experimental results revealed that -NH- and -NH2 represent major working sites of the employed compounds. The best result for CO2 sorption was attained for the amine-modified cellulose CL-D-400 with a sorption capacity of 409 µmol CO2/g at 1 bar and 1091 µmol CO2/g at 10 bar with amine concentrations as low as 2 × 10- 6 mol/mg.

Lithium-based sorbent from rice husk materials for hydrogen production via sorption-enhanced steam reforming of ethanol

The sorption-enhanced steam reforming of ethanol (SE-SRE) has the potential to produce the high-purity hydrogen. It is essential to obtain suitable reforming catalysts and CO2 sorbents in the SE-SRE process. We first prepared Ni-based catalysts by using three synthesis methods involving sol-gel, impregnation, and co-precipitation. Characterizations and catalytic activity tests results revealed that sol-gel route produced the most promising catalyst with 80% selectivity to H2 and the favorable structure of SG-Ni/Al2O3 was responsible for its superior performance. Then, different waste materials (rice husk ash, fly ash, kaolin) as silica source were employed to prepare Li4SiO4 sorbents for CO2 capture. The chemical composition of the silicon sources and the crystalline phase, specific surface area and morphology of these synthesized sorbents were characterized and results indicated that rick husk ash with large specific surface area and loose structure is the optimal silicon sources. Cyclic carbonation/calcination tests showed that RH-Li4SiO4 sorbent from rick husk material without acid treatment possesses the excellent CO2 sorption capacity up to 36.57 wt% and cyclic stability. The presence of impurity phases (MgO, Al2O3, K2O, etc.) in the RH-Li4SiO4 sorbent is beneficial to the CO2 adsorption. Moreover, the influence of steam on the CO2 capture of RH-Li4SiO4 sorbent was further investigated. We found that its CO2 adsorption performance was improved in the existence of steam. The integration of the optimized SG-Ni/Al2O3 catalyst and RH-Li4SiO4 sorbent with different packing methods was finally considered in the SE-SRE system. The four-layer interval packed catalyst and sorbent exhibited the best performance over the ten consecutive SE-SRE/regeneration cycles with a stable and high selectivity to H2 (>93%), confirming the potential for high-purity H2 by adsorption enhancement.

Novel Binders-Promoted Extrusion-Spheronized CaO-Based Pellets for High-Temperature CO2 Capture

Calcium looping (CaL) is a well-acknowledged approach in CO2 removal via the circulation of CaO-based sorbents between a carbonator and a calciner. During circulation, there is usually a quick decrease in CO2 sorption capacity and sorbent pellets experience severe attrition in fluidized-bed reactors, which are the two major challenges in CaL application. To develop sorbent pellets with high and stable sorption capacity and sufficient mechanical strength simultaneously, in this work, three kinds of novel phosphates were screened and utilized as binders in producing sorbent pellets via extrusion and spheronization, and their mechanical and chemical properties were tested and analyzed systematically. It was found that Mg3(PO4)2·4H2O was a good binder candidate in preparing CaO-based sorbent pellets with promoted mechanical and chemical performance. Under the optimum conditions of 10 wt % loading and 900 °C precalcination temperature, pellets of Ca8Mg1 (80 wt % Ca(OH)2 + 10 wt % Mg3(PO4)2·4H2O) demonstrated a compressive stress of 12.14 MPa and a CO2 uptake of 0.23 g-CO2/g-sorbent after 25 cycles, which were almost three times larger and 64% improved, respectively, compared to the typical Ca10 (pure Ca(OH)2). Additionally, the main reasons for performance enhancement were confirmed to be the production of Ca5(PO4)3(OH) with good hardness and the “spacer” effect of MgxCa1–xCO3.

Molecular Insights into Carbon Dioxide Sorption in Hydrazone-Based Covalent Organic Frameworks with Tertiary Amine Moieties.

Tailorable sorption properties at the molecular level are key for efficient carbon capture and storage and a hallmark of covalent organic frameworks (COFs). Although amine functional groups are known to facilitate CO2 uptake, atomistic insights into CO2 sorption by COFs modified with amine-bearing functional groups are scarce. Herein, we present a detailed study of the interactions of carbon dioxide and water with two isostructural hydrazone-linked COFs with different polarities based on the 2,5-diethoxyterephthalohydrazide linker. Varying amounts of tertiary amines were introduced in the COF backbones by means of a copolymerization approach using 2,5-bis(2-(dimethylamino)ethoxy)terephthalohydrazide in different amounts ranging from 25 to 100% substitution of the original DETH linker. The interactions of the frameworks with CO2 and H2O were comprehensively studied by means of sorption analysis, solid-state NMR spectroscopy, and quantum-chemical calculations. We show that the addition of the tertiary amine linker increases the overall CO2 sorption capacity normalized by the surface area and of the heat of adsorption, whereas surface areas and pore size diameters decrease. The formation of ammonium bicarbonate species in the COF pores is shown to occur, revealing the contributing role of water for CO2 uptake by amine-modified porous frameworks.