Ordered mesoporous silica (OMS) as an adsorbent and membrane for separation of carbon dioxide (CO2) (original) (raw)
Related papers
Engineering of Silica Mesoporous Materials for CO2 Adsorption
Materials
Adsorption methods for CO2 capture are characterized by high selectivity and low energy consumption. Therefore, the engineering of solid supports for efficient CO2 adsorption attracts research attention. Modification of mesoporous silica materials with tailor-made organic molecules can greatly improve silica’s performance in CO2 capture and separation. In that context, a new derivative of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, possessing an electron-rich condensed aromatic structure and also known for its anti-oxidative properties, was synthesized and applied as a modifying agent of 2D SBA-15, 3D SBA-16, and KIT-6 silicates. The physicochemical properties of the initial and modified materials were studied using nitrogen physisorption and temperature-gravimetric analysis. The adsorption capacity of CO2 was measured in a dynamic CO2 adsorption regime. The three modified materials displayed a higher capacity for CO2 adsorption than the initial ones. Among the studied sorbe...
Amine-modified ordered mesoporous silica: Effect of pore size on carbon dioxide capture
Chemical Engineering Journal, 2008
Three mesoporous silica materials with different pore sizes (33 Å for small pore size MCM-41; 38 Å for SBA-12; 71 Å for large pore size SBA-15) and pore connectivity (2D for MCM-41 and SBA-15-type materials; 3D for SBA-12 material) were prepared and functionalized with aminopropyl (AP) ligands by post-synthesis treatment. The materials were characterized by small angle X-ray scattering (SAXS), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and nitrogen adsorption/desorption experiments. The carbon dioxide sorption on modified mesoporous molecular sieves was investigated by using of microbalances at 25 • C, and the influence of pore size and pore architecture on CO 2 sorption was discussed. The large pore silica, SBA-15, showed the largest carbon dioxide sorption capacity (1.5 mmol/g), relating to highest amine surface density in this material. On the other hand, three-dimensional accessibility of amine sites inside the pores of SBA-12 silica resulted in a faster response to CO 2 uptake in comparison with MCM-41 and SBA-15 molecular sieves.
Journal of Porous Materials, 2020
In this study, the preparation of some large-pore ordered mesoporous silicas using a proper surfactant with different swelling agents was carried out. The synthesis of conventional SBA-15 was modified to obtain pore-expanded materials, with pore diameters up to 10 nm. To use a micelle swelling agent with a moderate swelling ability, three swelling agents were selected: 1-phenyl-decane (Dec), butyl benzene (BB), and mesitylene (Mes). These syntheses aimed to achieve a pore diameter enlargement but at the same time to avoid the formation of heterogeneous and/or poorly defined nanostructure of silica. The CO 2 adsorbents were obtained by post-synthesis functionalization treatments carried out by grafting with 3-aminopropyl triethoxysilane. The CO 2 adsorption/desorption experiments showed that carbon dioxide sorption capacities depend on the textural characteristics and the temperature used for the adsorption process. Good CO 2 adsorption capacities were obtained for all prepared adsorbents, especially for SSBA-15-Mes-sil and SSBA-15-BB-sil samples. At 50 °C, the SSBA-15-Mes-sil sample has an adsorption capacity of 3.58 mmol CO 2 /g SiO 2 , and an efficiency of amino groups of 0.99 mmol CO 2 /mmol NH 2. The results of adsorption capacities are comparable or even superior with the ones reported in literature for mesoporous silica functionalized with different amines. After nine adsorption-desorption cycles, the performance of the SSBA-15-Messil adsorbent is relatively stable, with a low decrease in the adsorption capacity (0.1 mmol/g of CO 2 , i.e., 2.8% of initial capacity). These studies show the potential of mesoporous silica for carbon dioxide capture.
Functionalised micro-/mesoporous silica for the adsorption of carbon dioxide
Microporous and Mesoporous Materials, 2007
SBA-16 silica was synthesised using the tri-block copolymer F127 as a surfactant. The copolymer was eliminated by calcination to 823 K or extraction with ethanol. These materials were functionalised with the diamine (CH 3 O) 3 Si-(CH 2 ) 3 -NH-(CH 2 ) 2 -NH 2 by post-synthesis grafting. TGA and DRIFT infrared spectroscopy revealed that the copolymer was not removed completely by extraction. For both methods the cubic pore structure of the synthesised silica remained intact which was corroborated by nitrogen isotherms and TEM measurements. The adsorption of carbon dioxide was studied with microcalorimetry at 300 K and up to 35 bars. The grafted silica samples show high enthalpies [À(90-100) kJ mol À1 ] at low pressures for the carbon dioxide adsorption. This was attributed to the initial interactions of the gas with the amine modified silica surface. With increasing carbon dioxide pressures the enthalpies decreased to values close to those observed with the non-grafted silica. The amounts of CO 2 adsorbed at 30 bar were $6.5 mmol g À1 for the non-grafted silica samples and 5.4 (extracted sample) and 4.6 mmol g À1 adsorbent (calcined sample) for the grafted silica materials, respectively.
CO2 Adsorption on Modified Mesoporous Silicas: The Role of the Adsorption Sites
Nanomaterials
The post-synthesis procedure for cyclic amine (morpholine and 1-methylpiperazine) modified mesoporous MCM-48 and SBA-15 silicas was developed. The procedure for preparation of the modified mesoporous materials does not affect the structural characteristics of the initial mesoporous silicas strongly. The initial and modified materials were characterized by XRD, N2 physisorption, thermal analysis, and solid-state NMR. The CO2 adsorption of the obtained materials was tested under dynamic and equilibrium conditions. The NMR data revealed the formation of different CO2 adsorbed forms. The materials exhibited high CO2 absorption capacity lying above the benchmark value of 2 mmol/g and stretching out to the outstanding 4.4 mmol/g in the case of 1-methylpiperazin modified MCM-48. The materials are reusable, and their CO2 adsorption capacities are slightly lower in three adsorption/desorption cycles.
Amine-modified ordered mesoporous silica: The effect of pore size on CO2 capture performance
Applied Surface Science, 2015
The objective of current research is to investigate the effect of pore size of mesoporous silica supports on the CO 2 capture performance of solid amine sorbents. Two ordered mesoporous silicas (OMS) with different pore sizes (5.6 nm and 7.6 nm) were synthesized as tetraethylenepentamine (TEPA) supports. A serious of techniques, such as physical adsorption, infrared spectroscopy and thermal gravimetric analysis were used to characterize the solid amine sorbents. The CO 2 capture performances of the sorbents were evaluated using breakthrough method with a fixed-bed reactor equipped with an online mass spectrometer. The experimental results indicate that the pore size has significant influence on CO 2 capture performance. Larger pore size could decrease the mass transfer resistance and increase the interaction between CO 2 and TEPA. Therefore, OMS-7.6 is better than OMS-5.6 as amine support. The highest CO 2 sorption capacities achieved with OMS-7.6 with 50 wt% TEPA loading (OMS-7.6-50) in the absence and presence of moisture are 3.45 mmol/g and 4.28 mmol/g, respectively, under the conditions of 10.0% CO 2 /N 2 mixture at 75 • C. Cyclic CO 2 adsorption-desorption experiments indicate that the solid amine sorbents are fairly stable and regenerable.
CO2 Adsorption on the N- and P-Modified Mesoporous Silicas
Nanomaterials
SBA-15 and MCM-48 mesoporous silicas were modified with functionalized (3-aminopropyl)triethoxysilane (APTES) by using the post-synthesis method, thus introducing N- and P-containing groups to the pore surface. The structure of the newly synthesized modifiers (aldimine and aminophosphonate derivatives of (3-aminopropyl)triethoxysilane and their grafting onto the porous matrix were proved by applying multinuclear NMR and FTIR spectroscopies. The content of the grafted functional groups was determined via thermogravimetric analysis. The physicochemical properties of the adsorbent samples were studied by nitrogen physisorption and UV–Vis spectroscopy. The adsorption capacity of CO2 was measured in a dynamic CO2 adsorption regime. The modified silicas displayed an enhanced adsorption capacity compared to the initial material. The 13C NMR spectra with high-power proton decoupling proved the presence of physically captured CO2. A value of 4.60 mmol/g was achieved for the MCM-48 material g...
Adsorption of CO2, CH4 and N2 on ordered mesoporous silica molecular sieve
Chemical Physics Letters, 2005
Separation of CO 2 and N 2 from CH 4 is significantly important in natural gas upgrading, and capture/removal of CO 2 , CH 4 from air (N 2) is essential to greenhouse gas emission control. Adsorption equilibrium and kinetics of CO , CH 4 , and N 2 on an ordered mesoporous carbon (OMC) sample were systematically investigated to evaluate its capability in the above two applications. The OMC was synthesized and characterized with TEM, TGA, small-angle XRD, and nitrogen adsorption/desorption measurements. Pure component adsorption isotherms of CO 2 , CH 4 and N 2 were measured at 278, 298, and 318 K and pressures up to 100 kPa, and correlated with the Langmuir model. These data were used to estimate the separation selectivities for CO 2 /CH 4 , CH 4 /N 2 , and CO 2 /N 2 binary mixtures at different compositions and pressures according to the ideal adsorbed solution theory (IAST) model. At 278 K and 100 kPa, the predicted selectivities for equimolar CO 2 /CH 4 , CH 4 /N 2 , and CO 2 /N 2 are 3.4, 3.7, and 12.8, respectively; and the adsorption capacities for CH 4 and CO 2 are 1.3 mmol/g and 3.0 mmol/g, respectively. This is the first report of a versatile mesoporous material that displays both high selectivities and large adsorption capacities for separating CO 2 /CH 4 , CH 4 /N 2 , and CO 2 /N 2 mixtures.
Tuning the textural properties of HMS mesoporous silica. Functionalization towards CO2 adsorption
Microporous and Mesoporous Materials, 2018
HMS mesoporous silica materials were prepared using different amines as structure directing agents. Textural properties showed a clear dependence on the molecule used, with too long and too short amines yielding significantly distorted structures. CO 2 adsorbents were obtained by loading additional amino groups on supports before (as made) or after removing the structure directing agent (extracted and calcined). Organic loading was performed by grafting with diethylenetriaminetrimethoxysilane (DT) and by impregnation with polyethyleneimine (PEI). CO 2 adsorption analyses showed a higher CO 2 uptake and amine efficiency (defined as the molar ratio CO 2 /N) for uniformly-structured adsorbents. Besides, as-made materials showed the best CO 2 adsorption properties due to a synergistic effect between loaded amines and those already present in the support. The influence of adsorption temperature, operation cycles and CO 2 concentration was also studied. A maximum CO 2 uptake of 4.19 mmol CO 2 /g (184 mg CO 2 /g) was registered in pure CO 2 (90 ºC, 1 bar), while a value of 1.80 mmol CO 2 /g was found in direct air capture conditions (400 ppm CO 2 , 45ºC, 1 bar).