CO2 adsorption performance of polyethyleneimine-modified ion-exchange resin

A series of solid amine adsorbents were prepared by the template method with ion-exchange resin (D001) as the carrier and polyethyleneimine (PEI) as the modifier. The absorbents were characterized by energy disperse spectroscopy (EDS), scanning electron microscope (SEM), N₂ adsorption–desorption, Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) techniques. The effects of PEI loading, adsorption temperature and influent velocities on CO₂ adsorption capacity in a fixed-bed reactor were investigated. The results show that the solid amine adsorbent prepared by the template method had a better PEI dispersion, stability and CO₂ adsorption capacity. The maximum CO₂ adsorption capacity was 3.98 mmol·g^?1 when PEI loading was 30%, the adsorption temperature was 65°C and the influent velocity was 40 mL·min^?1. The CO₂ adsorption capacity decreased only by 9.50% after 10 cycles of adsorption–desorption tests. The study of kinetics indicates that both chemical adsorption and physical adsorption occurred in the CO₂ adsorption process. The CO₂ adsorption process included fast breakthrough adsorption and gradually approaching equilibrium stage. The particle internal diffusion process was the control step for CO₂ adsorption.     

Carbon dioxide capture under postcombustion conditions using amine-functionalized SBA-15: Kinetics and multicyclic performance

ABSTRACT

In this work, ordered mesoporous SBA-15 was synthesized and functionalized by polyethyleneimine (PEI). The morphological properties were characterized by N₂ adsorption/desorption, field–emission scanning electron microscopy (FE-SEM), high–resolution transmission electron microscopy (HR-TEM) and Fourier transform infrared (FTIR) spectroscopy methods. The carbon dioxide (CO₂) uptake on the sorbents, kinetics of CO₂ adsorption/desorption and long-term multicycle stability of PEI-impregnated sorbent were measured. An optimal amine loading of 50 wt.% showed a CO₂ adsorption capacity ~3.09 mmol g^?1 using 10% pre-humidified CO₂ at 75°C. The presence of moisture in flue gas showed a promoting effect in CO₂ sorption capacity. The temperature swing adsorption/desorption cycles showed excellent multicycle stability over 60 cycles during 65 h of operations under humid CO₂.     

Highly Stable Amine-modified Mesoporous Silica Materials for Efficient CO2 Capture

A highly efficient and stable solid adsorbent invoking a direct incorporation of tetraethylenepentamine (TEPA) onto the as-synthesized mesocelullar silica foam (MSF) has been developed for CO₂ capture. Unlike most amine-functionalized silicas, which typically exhibit CO₂ adsorption capacities less than 2.0 mmol/g, such organic template occluded mesoporous silica-amine composites exhibited remarkably high CO₂ uptake as high as 4.5 mmol/g at 348 K and 1 atm. Moreover, notable increases in CO₂ adsorption capacities of the composite materials were observed when in the presence of humidity. Durability test performed by cyclic adsorption–desorption revealed that such adsorbents also possess excellent stability, even though a slight decrease in adsorption capacity over time was observed.     

Synthesis and CO2 adsorption behavior of amine‐functionalized porous polystyrene adsorbent

A solid amine adsorbent was prepared by modifying a porous polystyrene resin (XAD‐4) with chloroacetyl chloride through a Friedel–Crafts acylation reaction, followed by aminating with tetraethylenepentamine (TEPA). The adsorption behavior of CO₂ from a simulated flue gas on the solid amine adsorbent was evaluated. Factors that could determine the CO₂ adsorption performance of the adsorbents such as amine species, adsorption temperature, and moisture were investigated. The experimental results showed that the solid amine adsorbent modified with TEPA (XAD‐4‐TEPA), which had a longer chain, showed an amine efficiency superior to the other two amine species with shorter chains. The CO₂ adsorption capacity decreased obviously as the temperature increased because the reaction between CO₂ and amine groups was an exothermic reaction, and its adsorption amount reached 1.7 mmol/g at 10 °C in dry conditions. The existence of water could significantly increase the CO₂ adsorption amount of the adsorbent by promoting the chemical adsorption of CO₂ on XAD‐4‐TEPA. The adsorbent kept almost the same adsorption amount after 10 cycles of adsorption–desorption. All of these results indicated that amine‐functionalized XAD‐4 resin was a promising CO₂ adsorbent. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45046.     

Effects of different structure-directing agents (SDA) in MCM-41 on the adsorption of CO2

CO₂ capturing technologies have attracted significant attention in order to limit emissions and reduce their negative effect on the environment. Mesoporous silica materials (MCM-41) are easily recyclable, affordable, and thermally and mechanically stable, providing added benefits in CO₂ capture. However, further studies are necessary to characterize the effects of MCM-41 pore size, adsorption temperature and surface silylation on CO₂ adsorption efficiency. In this work, mesoporous silica is synthesized using alkyltrimethylammonium bromide with different chain lengths (C_nH_2n + 1 N(CH₃)₃Br, n = 14, 16 and 18) as structure-directing agents, and the adsorption capacity of CO₂ on TTMCM-41 (C₁₇H₃₈NBr), CTMCM-41 (C₁₉H₄₂NBr), DTMCM-41(C₂₁H₄₆NBr) samples was measured gravimetrically at room temperature and pressure up to 40 bar. The silica structures were characterized by X-ray diffraction (XRD), nitrogen adsorption/desorption, Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy (TEM). The XRD, N₂ adsorption–desorption and TEM measurements indicated the presence of a well-ordered hexagonal array with uniform mesostructures. The mesoporous silica obtained, denoted as TTMCM-41, CTMCM-41 and DTMCM-41, had distinct physical properties, such as BET surface area, hexagonal unit cell, pore volume, pore diameter and pore wall thickness. CTMCM-41 exhibited an adsorption capacity (0.58 g CO₂/g adsorbent) of more than DTMCM-41 (0.48 g CO₂/g adsorbent) and TTMCM-41 (0.42 g CO₂/g adsorbent). The results suggest that CTMCM-41 can be a better mesoporous adsorbent for CO₂ adsorption .     

超枝化固体胺吸附分离烟气中二氧化碳

采用浸渍方法将四乙烯五胺（TEPA）负载到KIT-6介孔硅材料孔道表面上合成超枝化固体胺KIT-6(TEPA),并对其吸附CO₂性能进行研究。结果表明,随着温度的升高,KIT-6(TEPA)的CO₂吸附量呈增长趋势,343 K时获得最大吸附量（3.1 mmol·g^-1）。继续升高温度吸附量则呈下降趋势。KIT-6(TEPA)吸附CO₂过程以化学吸附为主,化学吸附量占总吸附量的97.2%以上（323相似文献   

Mixed-amine Modified SBA-15 as Novel Adsorbent of CO2 Separation for Biogas Upgrading

A novel adsorbent of CO₂ from biogas was prepared by synthesizing and modifying the mesoporous molecular silica of SBA-15 with methyl-diethyl-amine (MDEA) and piperazine (PZ). The adsorbent showed good performance in separating CO₂ from biogas. The loaded amines did not change the ordered structure of SBA-15, but enhanced its adsorption of CO₂. The adsorbents were characterized by X-ray powder diffraction (XRD) and N₂ adsorption/desorption. With the increase in MDEA loading, the surface area, pore size, and pore volume of the MDEA-loaded SBA-15 decreased. The modification of amines enlarged the difference between the equilibrium adsorption of CO₂ and CH₄. Quantitatively evaluated on the basis of the breakthrough curves, the separation factors between CO₂ and CH₄, was increased more than seven fold due to the MDEA modification. With mixed-amine (MDEA + PZ) modification, the separation factors between CO₂ and CH₄ was further improved. In addition, not only the adsorbent was regenerable by purging with the purified gas, but also the adsorption performance is stable in adsorption cycles. Effect of moisture on adsorption of CO₂ is investigated and the results show the increase in the adsorption performance.     

Influence of Drying Conditions on Amine-Functionalized SBA-15 as Adsorbent of CO2

Adsorption of pure CO₂ on amine-functionalized SBA-15 mesoporous silica materials has been studied. Adsorbent materials were prepared by grafting the silica surface with aminopropyl (AP), ethylene-diamine (ED) and diethylene-triamine (DT) organosilane molecules. Materials so obtained were dried under air atmosphere at 110 °C and at room temperature. CO₂ adsorption isotherms were carried out at 45 °C, showing that grafted materials are very efficient for CO₂ removal at atmospheric pressure when samples are dried at 20 º C. However, when the drying step is carried out at 110 °C in air, CO₂ adsorption capacity is low. DRIFTS analysis has shown that amino groups can undergo oxidation to oxime or imine species during drying. Adsorption capacity of the materials was found to be unchanged after some consecutive adsorption?Cdesorption cycles, being the regeneration step performed at 110 °C under vacuum.     

CO<Subscript>2</Subscript> adsorption at high pressures in MCM-41 and derived alkali-containing samples: the role of the textural properties and chemical affinity

The adsorption properties of N₂ and CO₂ of MCM-41 and derived alkali-containing samples were analyzed over a wide range of pressures (up to ~4500 kPa) and temperatures (between 30 and 300 °C). The high-pressure and high-temperature experiments were carried out on pure MCM-41 and K- and Na-impregnated derived samples. It was analyzed the influence of pressure and temperature on the CO₂ capture capacity on pure and impregnated samples. The adsorption performance was correlated to the structure and textural properties of the materials using X-ray diffraction and N₂ adsorption–desorption measurements. The addition of an alkaline element changes the textural properties of the material increasing the pore size, which positively affected the CO₂ adsorption capacity of these materials at high pressure. In addition, the isosteric heats of adsorption gave information about the chemical affinity between the impregnated materials and CO₂. The CO₂ adsorption at ~ 4500 kPa for the samples with 5 wt% Na at 100 and 200 °C were 77.98 and 9.79 mmol g^?1, respectively, while the pure MCM-41 adsorbs only 8.92 mmol g^?1.     

Preparation of amine-modified SiO<Subscript>2</Subscript> aerogel from rice husk ash for CO<Subscript>2</Subscript> adsorption

Amine-modified SiO₂ aerogel was prepared using 3-(aminopropyl)triethoxysilane (APTES) as the modification agent and rice husk ash as silicon source, its CO₂ adsorption performance was investigated. The amine-modified SiO₂ aerogel remains porous, the specific surface area is 654.24 m²/g, the pore volume is 2.72 cm³/g and the pore diameter is 12.38 nm. The amine-modified aerogel, whose N content is up to 3.02 mmol/g, can stay stable below the temperature of 300 °C. In the static adsorption experiment, amine-modified SiO₂ aerogel (AMSA) showed the highest CO₂ adsorption capacity of 52.40 cm³/g. A simulation was promoted to distinguish the adsorption between the physical process and chemical process. It is observed that the chemical adsorption mainly occurs at the beginning, while the physical adsorption affects the entire adsorption process. Meanwhile, AMSA also exhibits excellent CO₂ adsorption–desorption performance. The CO₂ adsorption capacity dropped less than 10 % after ten times of adsorption–desorption cycles. As a result, AMSA with rice husk ash as raw material is a promising CO₂ sorbent with high adsorption capacity and stable recycle performance and will have a broad application prospect for exhaust emission in higher temperature.     

Adsorption of CO<Subscript>2</Subscript> by iron-exchanged heteropolyacid Fe<Subscript>1.5</Subscript>PMo<Subscript>12</Subscript>O<Subscript>40</Subscript> supported on mesoporous cellular foams

Novel low-temperature swing adsorbents that preferably adsorb CO₂ were synthesized by varying loading of heteropolyacid Fe_1.5PMo₁₂O₄₀ (Fe–PMA) supporting on mesoporous cellular foams (MCFs) by wetting impregnation. The synthesized materials were characterized by various physicochemical, thermal and spectral techniques and the CO₂ adsorption capacity of the materials were evaluated. Solid adsorbents showed a significantly high adsorption capacity toward CO₂ due to the chemisorptions of CO₂. The CO₂ adsorption capacities of the materials decreased as the temperature increased. The results showed that the adsorption capacity reached a level of 81.8 mg CO₂/g-adsorbent at 25 °C for the 20 wt% Fe–PMA–MCFs. These results indicated that the iron (Fe²⁺) complexes acted as efficient catalysts for the separation of CO₂. The as-synthesized adsorbents were selective, thermally stable, long-lived, and could be recycled at a temperature of 110 °C.     

CO2 sorption performance by aminosilane functionalized spheres prepared via co‐condensation and post‐synthesis methods

Amine functionalized silica microspheres were synthesised via a modified Stöber reaction for carbon dioxide (CO₂) adsorption. A number of adsorbents were synthesized by co‐condensation and post synthesis immobilization of amines on porous silica spheres. CO₂ adsorption studies were carried out on a fixed bed gas adsorption rig with online mass spectrometry. Amine co‐condensed silica spheres were found to adsorb up to 66 mg CO₂ g^?1 solid in a 0.15 atm CO₂ stream at 35°C. Simple post‐synthesis addition of aminopropyltriethoxysilane to amine co‐condensed silica was found to significantly increase the uptake of CO₂ to 211 mg CO₂ g^?1 under similar conditions, with CO₂ desorption commencing at temperatures as low as 60°C. The optimum temperature for adsorption was found to be 35°C. This work presents a CO₂ adsorbent prepared via a simple synthesis method, with a high CO₂ adsorption capacity and favorable CO₂ adsorption/desorption performance under simulated flue gas conditions. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2825–2832, 2016     

Influence of regeneration conditions on the cyclic performance of amine-grafted mesoporous silica for CO2 capture: An experimental and statistical study

This work deals with the behavior of amine-grafted mesoporous silica (referred to as TRI-PE-MCM-41) throughout adsorption–desorption cycles in the presence of 5% CO₂/N₂ using various regeneration conditions in batch experiments. The criteria proposed to determine the optimum regeneration conditions are the working adsorption capacity, the rate of desorption and the change of adsorption capacity between consecutive cycles. Using a 2³ factorial design of experiments, the impact on the performance of the adsorbent of different levels of temperature, pressure, and flow rate of purge gas during desorption was determined. It was found that all the parameters under study have a statistically significant influence on the working adsorption capacity, but only temperature is influential with respect to desorption rate. Regeneration using temperature swing was found to be attractive, as the highest CO₂ adsorption capacity (1.95 mmol g^?1) and the fastest desorption rate (9.82×10^?4 mmol g^?1 s^?1) occurred when desorption was carried out at 150 °C. However, if vacuum is applied, regeneration can be achieved at a temperature as low as 70 °C with only a 13% penalty in terms of working adsorption capacity. It was also demonstrated that under the proper regeneration conditions, TRI-PE-MCM-41 is stable over 100 adsorption–desorption cycles.     

Effect of La as Promoter in the Photoreduction of CO<Subscript>2</Subscript> Over TiO<Subscript>2</Subscript> Catalysts

In this work, TiO₂ has been modified by treating it thermally together with different proportions (0.5–15 wt%) of La₂O₃. The resulting materials have been extensively characterized by XRD, TEM, N₂ adsorption isotherms, temperature-programmed CO₂ desorption, Raman, UV–Vis photoluminescence and X-ray photoelectron spectroscopies. The activity tests of these materials for the gas-phase photocatalytic reduction of carbon dioxide show that the main products of the reaction are in all cases CO and CH₄, together with H₂ from the parallel reduction of water. After the preparation procedure, La phases are best described as oxycarbonates, and lead to improved activity with respect to TiO₂ with La contents up to 5 wt%. Higher loadings do not, however, lead to further enhanced activity. Retarded electron–hole recombination and enhanced CO₂ adsorption are invoked as the key factors contributing to this activity improvement, which is optimized in the case of 0.5 wt% La leading to higher productions of CO and CH₄ and increased quantum efficiency with respect to titania.     

CO2 Adsorption by Modified Palm Shell Activated Carbon (PSAC) Via Chemical and Physical Activation and Metal Impregnation

The aim of this study was to verify the ability of nickel-impregnated palm shell activated carbon (PSAC) for CO₂ adsorption and compare its performance with the chemically and physically activated PSAC. Sodium hydroxide and CO₂ were used as activating agents for chemical and physical activation, respectively. Nickel nitrate hexahydrate (Ni(NO₃)₂·6H₂O) was used as a precursor for metal impregnation. The effect of different chemical loadings (NaOH: 20–50 wt%), metal impregnation (Ni(NO₃)₂·6H₂O: 16–28 wt%), and heat treatment time (1–4 h) was studied as parameters. Adsorption capacity was calculated using breakthrough graphs. The effect of humidity on CO₂ adsorption and desorption of CO₂ was also investigated in this study. The results revealed that chemically modified PSAC yields the highest adsorption capacity (48.2 mg/g) compared to other methods of activation. Interestingly, it was found that the adsorption capacity of nickel-impregnated PSAC was similar to other types of metal-impregnated activated carbon. Humidity gave a negative effect on CO₂ adsorption. In summary, results showed that chemical activation is an efficient technique to modify PSAC for CO₂ adsorption.     

Hydrophobically modified nano-SiO2 in situ loaded on polyurethane foam as a potential carrier for marine oil spill

In order to enhance the oil–water separation properties of polyurethane foam (PFU), hydrophobic silica nanoparticles (H-SiO₂ NPs) were firstly prepared by incorporating long alkyl chains into silica nanoparticles, and then, it was combined with PFU by in situ loading to fabricate a hydrophobic PFU (H-SiO₂ NPs/PUF). When the loading amount of H-SiO₂ NPs was 10%, the water contact angle of the modified foam H-SiO₂ NPs/PUF-10 reached 147 ± 1°, which proved it was highly hydrophobic. The elongation at break of the foam was increased by 202%, which indicated that it had better resilience and recyclability. In addition, the total pore area and porosity were increased to 16.24 m²/g and 88.43% from 5.46 m²/g and 2.11%, which provided more storage space for adsorption. The oil–water separation experiment showed that the adsorption capacity for most light oils was 11–13 g/g, and that for dichloromethane was as high as 40.5 g/g. After 10 adsorption–desorption cycles, the adsorption capacity only decreased from 15.6 to 14.5 g/g, which was still 93% of the initial adsorption capacity. H-SiO₂ NPs/PUF represents good adsorption capacity, recyclability, and recyclability, so it as a carrier has a potential application in the treatment of marine oil spills.     

拟薄水铝石负载PEI/AMP吸附CO2性能

用富含胺基的物质对多孔材料进行修饰可以得到高CO₂吸附量的吸附剂。采用浸渍法将聚乙烯亚胺(PEI)和2-氨基-2-甲基-1-丙醇(AMP)负载在拟薄水铝石上,考察了CO₂压力、胺类物质负载量等对吸附性能的影响。采用低温N₂吸附/脱附法(BET)、扫描电镜(SEM)、傅里叶变换红外线光谱分析仪(FTIR)等手段表征了吸附剂的结构特征及其物理性质,并使用重量法微天平实验装置对吸附剂的性能进行了评价。实验结果表明,当温度恒定为50℃,压力小于1 MPa时,负载PEI的吸附剂最高的CO₂吸附量为77.53 mg CO₂·(g吸附剂)^-1,最佳负载量为85%;压力大于1 MPa时,负载PEI的吸附剂最高的CO₂吸附量为123.79 mg CO₂·(g吸附剂)^-1,最佳负载量为10%。负载AMP的吸附剂最高的CO₂吸附量为128.01 mg CO₂·(g吸附剂)^-1,最佳负载量为85%。CO₂吸附稳定性实验表明,吸附剂对CO₂的吸附性能稳定。     

The Role of Organically Modified Clay Particle on Thermal,Mechanical and Gas Barrier Properties of Polyimide Nanocomposites and Toward Improvement of Gas Selectivities

ABSTRACT

Novel mixed matrix membranes with various Cloisite®15A in polyimide (PI) matrix were developed for gas separation. The synthesized membranes were characterized by the FE-SEM, XRD, DTG and TEM. According to FE-SEM results, at 3 wt% of Cloisite®15A, the fillers were dispersed homogeneously in the PI polymer matrix. The tensile properties of PI/Cloisite®15A increased gradually with clay content. It was interesting to note that the pure gas selectivity was seen to be increased with decreasing the filler loading. At 1 wt% clay loading, PI/Cloisite®15A nanocomposites showed an increase of 55% in CO₂/CH₄ ideal selectivity over pristine PI membrane.     

Synthesis and evaluation of NiO@MCM-41 core–shell nanocomposite in the CO<Subscript>2</Subscript> reforming of methane

In this paper, the synthesis of core shell structured NiO@MCM-41 nanocomposite via vesicles as soft template is reported for the first time. Its catalytic performance was investigated in the CO₂ reforming of methane (CRM) conversion. Stable vesicles first formed with CTAB/SDBS surfactant ratio of 1:2. Nickle nitrate was added to the vesicle mixture followed by addition of the aqueous solution of vesicle containing Ni cations inside to the MCM-41 gel. After high-temperature calcination, NiO@MCM-41 nanocomposite were obtained. The structural symmetry and the surface morphology were characterized by transmission electron microscope (TEM), low angle X-Ray Diffraction (XRD) and N₂ adsorption/desorption analysis. TEM image confirmed core–shell structure and the hexagonally ordered structure of shell of MCM-41 silica. The results indicated that the average diameter of synthesized core–shell NiO@MCM-41 particles is 70–80 nm and the most of them are of spherical shape. The result of small angle XRD and N₂ isotherm adsorption/desorption analyses indicated successfull formation of mesoporous shell. Hydrogen consumption by the catalyst mainly at 700 °C in TPR profile showed the strong interaction of the most of Nickel content with the support. CRM conversion on the prepared catalyst after 245 min of reaction led to H₂ conversion at 42%, CO₂ conversion at 48% with H₂/CO yield ratio of 0.8.     

Greenhouse Gas Adsorptivity of Horn-Shaped Carbon Nanotubes over Nitrogen: Equilibrium Study

The synthesis of horn-shaped carbon nanotubes using carbon tetrachloride as carbon source was carried out by solvothermal method at 200°C for 2 h. The scanning and transmission electron microscopic characterization of the obtained product showed the formation of horn-shaped carbon nanotubes with irregular wall structure having inner diameter of ～105 nm and length of ～1 µm. The equilibrium gas adsorption properties of horn-shaped carbon nanotubes derived from carbon tetrachloride were successfully investigated for CO₂, CH₄, and N₂ at 288, 303, and 318 K. Horn-shaped carbon nanotubes possess better CO₂ adsorption capacity (2.53 mmol/g) with high capacity selectivity (14.7) and equilibrium selectivity (59.1) over N₂ at 288 K. The detailed adsorption study with estimation of physical parameters such as Henry's constant and heat of adsorption identifies the horn-shaped carbon nanotubes as a potential adsorbent material in the field of CO₂ storage and separation.