Synthesis and CO2 Adsorption Properties of Molecularly Imprinted

Article pubs.acs.org/est

Synthesis and CO2 Adsorption Properties of Molecularly Imprinted Adsorbents Yi Zhao,* Yanmei Shen, Lu Bai, Rongjie Hao, and Liyan Dong School of Environmental Science & Engineering, North China Electric Power University, Baoding 071003, People’s Republic of China S Supporting Information *

ABSTRACT: A series of molecularly imprinted adsorbents of CO2 were developed by molecular self-assembly procedures, using ethanedioic acid, acrylamide, and ethylene glycol dimethacrylate as template, functional monomer, and cross-linker, respectively. Textural properties of these adsorbents were characterized by N2 adsorption experiment, thermo-gravimetric analysis, and Fourier transform infrared spectroscopy. CO2 adsorption capacities of adsorbents were investigated by thermo-gravimetric balance under 15% CO2/ 85% Ar atmosphere. Adsorption selectivity of CO2 was studied by fixed-bed adsorption/desorption experiments. All the adsorbents displayed good thermal stability at 200 °C. Among them, MIP1b, with the higher amine content, exhibited the largest CO2 capacity, which maintained steady after 50 adsorption−desorption cycles. Although MIP3 showed the highest specific surface, the CO2 capacity was lower than that of MIP1b. CO2 adsorption mechanism of molecularly imprinted adsorbents was determined to be physical sorption according to the adsorption enthalpies integrated from the DSC heatflow profiles. The calculated separation factors of CO2 under 15% CO2/85% N2 atmosphere were above 100 for all adsorbents.

1. INTRODUCTION To cope with the worldwide demand for carbon dioxide (CO2) reduction, considerable attention has been attracted to CO2 capture and storage (CCS) process from power generation plants.1−3 In this process, the development of cost-effective techniques for capture CO2 is considered to be one of the highest priorities, because the cost of capturing CO2 alone is generally estimated to account for three-fourths of the total costs of ocean or geologic sequestration.1 Adsorption is one promising CO2 capture technique that could be less costly and energy efficient, and it overcomes the disadvantages of traditional liquid amine-based absorption processes, including solvent degradation, equipment corrosion, and foaming in the gas−liquid interface.4 Generally, CO2 adsorbents can be classified into three groups:5 inorganic porous materials including activated carbon, zeolites, and silicas;6−9 hydrotalcite materials and basic oxide;10−12 and porous hybrid materials such as metal organic frameworks (MOFS).13,14 Among them, inorganic porous adsorbents have been used in commercial run of ammonia to capture CO2, but their low adsorption capacity and selectivity as well as their requirement of dehumidification bring some limitations when applied for power plant flue gas.8 The other two groups of CO2 adsorbents are still limited to lab research and hard to apply in practical CO2 capture processes for severe energy penalties during regeneration.5 Recently, some research has been focusing on modifying mesoporous materials by basic centers to improve the © 2012 American Chemical Society

adsorption properties. Although these modified mesoporous materials commonly could take advantage of high selectivity and capacity to CO2, they have been difficult to prepare. Xu et al. developed a CO2 “molecular basket” adsorbent by loading polyethylenimine (PEI) into MCM-41, the CO2 uptake of which was 30 times larger than that of MCM-41.15,16 However, the preparation involved the hydrothermal synthesis of MCM41 by reacting 100 °C for 40 h, drying at 100 °C overnight, and calcining at 550 °C for 5 h, and the PEI modification by using toxic solvent, methanol, and drying at 70 °C for 16 h under reduced pressure. Wei et al.17 functionalized SBA-16 with aminosilane, and obtained high adsorption capacity of CO2 at 60 °C, but the synthesis of SBA-16 required 3 days for aging and 6 h for calcination at 550 °C, and the functionalization required inert atmosphere and toxic solvent, methanol. Similar studies also can be found in many other works.18,19 In this work, a kind of molecularly imprinted CO2 (MIPCO2) adsorbent has been developed. Molecular imprinting is a method of inducing molecular recognition properties in synthetic polymers in response to the presence of a template species during formation of the three-dimensional structure of the polymer. 20,21 The synthetic processes of MIP-CO 2 adsorbents were identical to the traditional molecular Received: Revised: Accepted: Published: 1789

October 8, 2011 December 17, 2011 January 12, 2012 January 12, 2012 dx.doi.org/10.1021/es203580b | Environ. Sci. Technol. 2012, 46, 1789−1795

Environmental Science & Technology

Article

Table 1. Reagent Dosages and Preparation Conditions of Adsorbents samplesa group 1

group 2

MIP1 MIP1a MIP1b MIP1c MIP2 MIP3 NIP

ethanedioic acid (mmol)

AAM (mmol)

reaction condition

solvent

4 8 12 16 4 4 4

60 °C w/o UV 60 °C w/o UV 60 °C w/o UV 60 °C w/o UV ambient temperature w/UVc 60 °C w/o UV 60 °C w/o UV

AN AN AN AN AN AN/toluene = 1/1d AN

1 1 1 1 1 1 0

b

a

Group 1: MIP adsorbents prepared by varying the reaction condition and solvents, and nonimprinted material (NIP); Group 2: adsorbents prepared by varying the content of AAM. bw/o UV: without untravilot radiation. cw/UV: with untravilot radiation. dThe solvent is a mixture of AN and toluene in the ratio 1/1.

(BJH) method. Total pore volume was calculated from the amount of absorbed N2 at P/P0 = 0.99. Thermal stabilities of adsorbents were characterized by thermo-gravimetric analysis (TGA) (Netzch STA 449C, German). Adsorbents were predried at 120 °C before thermal characterization to remove moisture. Ten mg of the adsorbents were heated from 25 to 600 °C. The Fourier transform infrared (FTIR) spectra of samples were obtained using FTIR spectrometer (Thermo Nicolet 380, USA). 2.4. CO2 Adsorption/Desorption. CO2 adsorption/ desorption measurements was performed on DSC-TGA (Netzch STA 449C, German). Fifteen % CO2/85% Ar gas mixture was used for the adsorption study. Ten mg samples were first activated by flowing Ar with a flow rate of 20 mL/min at 120 °C for 2 h before adsorption, then cooled to adsorption temperature prior to exposure to the CO2/Ar mixture with a flow rate of 15 mL/min for 50 min. CO2 adsorption capacities were determined based on the rapid weight gain of adsorbents upon introduction of the CO2/Ar mixture. The adsorption enthalpies were calculated based on DSC heatflow profiles. After adsorption, the gas was switched to pure Ar at the same flow rate to perform desorption at the same temperature. CO2 selectivity and adsorption stability of adsorbents were investigated by a fixed bed absorber. In a typical adsorption/ desorption process, 2.5 g of the prepared adsorbent was loaded into a quartz column (10 mm O.D.; 5 mm I.D.) wound with a heating tape. Three thermal couples located at inlet and outlet as well as inside of the cell were used to monitor the temperatures during operation. The temperature could be controlled within ±0.5 °C. The initial activation of adsorbents was carried out at 120 °C for 2 h in Ar atmosphere with a flow rate of 100 mL/min. The adsorption run was operated by flowing 15% CO2/85% N2 mixture with a flow rate of 200 mL/ min at 60 °C, the desorption run was conducted in a N2 flow at 120 °C. The gas flow rate was controlled by mass flow meter (Rotamass, RCCS, German). The CO2 concentration in effluent gas stream at the outlet of the absorber column was measured by a CO2 infrared analyzer (Zhonghui, NKJH-3860B, China). N2 concentration in effluent gas was calculated by subtracting the concentration of CO2 from the effluent gas mixture. The CO2/N2 selectivity was assessed by separation factor which is defined as the mole ratio of the gases adsorbed by the adsorbent, (nCO2/nN2)adsorbed, over the mole ratio of the gases fed into the adsorbent bed, (nCO2/nN2)feed (eq 1).15 The adsorption stabilities of adsorbents were investigated by 50 cycles of CO2 adsorption/desorption.

imprinting process, except that the template molecule was not the targeted CO2 molecular but ethanedioic acid as the substitution. The synthesized MIP-CO2 adsorbents had basic centers and porous properties similar to those of aminemodified silica, and exhibited large adsorption capacity and high CO2/N2 selectivity. Besides, it was time saving, energy saving, and easy to prepare, because the selective amine recognition sites were introduced directly without second modification.

2. EXPERIMENTAL SECTION 2.1. Reagents. Ethanedioic acid, acrylamide (AAM), ethylene glycol dimethacrylate (EGDMA), azodiisobutyronitrile (AIBN), acetonitrile (AN), toluene, methanol, and hydrochloric acid (HCl, 20 wt %) were purchased from Kermel Chemical Reagent Ltd. (Tianjin) and were analytical reagent grade. High purity water (>18 MΩ) was produced by lab water purification system (Changfeng Co., Ltd., Beijing). All gases used in this work had purity higher than 99.99%, and were supplied by Beiyang Co., Ltd. 2.2. Synthesis of MIP-CO2 Adsorbents. A series of MIPCO2 adsorbents were synthesized by the following method: Ethanedioic acid and AAM were dissolved in 10 mL of solvent for 2 h with agitation followed by adding 20 mmol of EGDMA and 0.3 mmol AIBN. The mixture was then degassed by ultrasonic device for 15 min and purged with N2 for another 10 min to remove oxygen. After that, the mixture was sealed and reacted for 24 h at the reaction condition given in Table 1. The resultant polymers were ground and screened to 50−150 μm. The particles were washed with HCl/methanol (1/9, vol/vol) solution to remove ethanedioic acid and then filtered off. The washing procedure was repeated several times until the template could not be detected in filtrate. The remaining particles were washed with high-purity water to neutral and then dried overnight under vacuum at 60 °C. The reagent dosages and reaction conditions of adsorbents are listed in Table 1. Nonimprinted material (NIP) without using template was also prepared in parallel with the MIP-CO2 adsorbents by the same synthetic protocol. 2.3. Characterization. N2 adsorption/desorption experiments were performed with a surface area and pore size analyzer (Beckman Coulter SA 3100, USA). Each sample was outgassed under vacuum for 2 h at 150 °C prior to measurement. Surface area was calculated by Baunauer− Emmett−Teller (BET) equation; the Ps/P0 range over which the BET surface areas were calculated was 0.05−0.2. Pore size and distribution were determined by Barrett−Joyner−Halenda 1790

dx.doi.org/10.1021/es203580b | Environ. Sci. Technol. 2012, 46, 1789−1795


αCO2 /N2 =

(nCO /nN )adsorbed (nCO /nN )feed 2

Article

2

2

2

(1)

3. RESULTS AND DISCUSSION 3.1. Preparation and Characterization of MIP-CO2 Adsorbents. The synthetic strategy of MIP-CO2 adsorbent is shown in Figure 1. During the synthesis, the functional

Figure 2. N2 adsorption isotherms (A) and pore size distribution curves (B) of the prepared MIP-CO2 adsorbents in group 1 and group 2.

low-temperature polymerization can avoid the swelling phenomena and is favorable to form ordered structure of polymer. SBET and Vp of MIP3 are slightly higher than those of MIP1, which may be because the addition of toluene in solvent leads to stronger porogenic effect on polymer. For NIP, SBET and Vp are the lowest among all the prepared samples, moreover, macropores (>100 nm) account for a certain proportion in the structure, and the pore size is not uniform. This suggests that template plays a structure-directing role and helps to improve the specific area and form ordered structure. With an increase of AAM content in polymer, SBET of adsorbents in group 2 decreases in the order of MIP1a > MIP1b > MIP1c. Macropores larger than 100 nm occupy a certain proportion of the structure of MIP1c, but they are not observed in the structure of MIP1a and MIP1b (see Figure 2B). The main reason is that an increase of the proportion of AAM in polymer correspondingly decreases the cross-linking degree of polymer and thus affects the textural properties of polymers. MIP1a, with the highest cross-linking degree, is a network structure resulting from gathering into clusters of the molecules, leading to relatively higher surface area and smaller pore size. However, with the decrease of cross-linking degree, the structure of MIP-CO2 adsorbents transition from network to linear, hence, SBET and Vp decrease and dp increases correspondingly. TGA curves of adsorbents are shown in Figure 3. No obvious mass loss is observed in the temperature range of 25−200 °C due to the predrying of adsorbents. However, 5% weight loss of adsorbents occurs at 340 °C for MIP1, 360 °C for MIP2, 340 °C for MIP3, 330 °C for NIP, 300 °C for MIP1a, 280 °C for MIP1b, and 230 °C for MIP1c, in which most of the samples display good thermo-stability at 300 °C except for MIP1a, MIP1b, and MIP1c, suggesting that the decrease of crosslinking degree of polymers will decrease the stability of polymer. The best thermo-stability of MIP2 indicates that photopolymerization is beneficial to the stability of the polymers. The temperatures corresponding to 5% weight loss of MIP1, MIP3, and NIP are similar, which suggests that the variation of solvent and template during the preparation process does not have obvious effect on the thermo-stability of polymers. It has been reported that the weight loss of mesoporous materials grafted by aminopropyl ligand appeared

Figure 1. Synthetic strategy of MIP-CO2 adsorbents: (a) AAM molecules are arranged in a complementary configuration to ethanedioic acid; 1 is the complex of AAM and ethanedioic acid formed by hydrogen-bonding; (b) copolymerizing with EGDMA to give the polymer; (c) template removal; (d) reversible rebinding of CO2 by hydrogen-bonding or intermolecular force.

monomer (AAM) first arranged in a complementary configuration to template (ethanedioic acid) by self-association, forming complex 1 in which the oxygen atom of ethanedioic acid was bonded to the amino group of AAM. The cross-linker, EGDMA, was then added to give a porous polymer containing nascent imprint sites. After removal of template from the polymer by washing with HCl/methanol solution, the vacant imprinted sites were then available for adsorbing CO2. A 3D model of polymer with 8 molecules of AAM and 2 molecules of template was established by Chembio3D. The distances between adjacent N atoms calculated from 3D model were in the range of 0.489 and 0.694 nm, while the aerodynamic diameter of CO2 was 0.33 nm, making it quite suitable for the insertion of CO2 molecule. Figure 2 shows N2 adsorption isotherms and pore distribution curves of prepared adsorbents. Specific surface area (SBET), pore volume (Vp), and average pore diameter (dp) are summarized in Table 2. SBET and Vp were calculated from N2 adsorption isotherm. dp was estimated by dp = 4Vp/SBET. The isotherms for all the adsorbents except MIP2 are of type II characteristic (see Figure 2A), which shows feature of not uniform distribution of pore size. The isotherm of MIP2 exhibits type IV pattern showing feature of uniform distribution of pore size. SBET, Vp, and dp of adsorbents in group 1 (see Table 2) vary with the reaction conditions and solvents. By contrast, SBET, Vp, and dp of MIP1 are lower than those of MIP2, which may be due to the swelling effect during thermalinitiation reaction. As shown in Figure 2B, the pore size of MIP2 is relatively uniform (∼8 nm) which may be because the 1791



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Table 2. Textural Properties and CO2 Adsorption Characteristics of Adsorbents samples group 1

group 2

MIP1 MIP1a MIP1b MIP1c MIP2 MIP3 NIP a

SBET (m2/g)

Vp (mL/g)

dp (nm)

amine contents (mmol(N)/g)

adsorption enthalpiesa (kJ/mol)

CO2 capacitiesa (mmol/g)

CO2/N ratios (mol/mol)

separation factors

225.67 158.51 97.134 84.658 122.42 258.19 75.26

0.6641 0.6670 0.5675 0.5177 0.2596 0.7477 0.2493

12 17 23 24 8 12 11

0.94 1.74 2.47 3.11 0.94 0.94 0.94

25 32 36 34 22 28 27

0.418 0.455 0.478 0.464 0.398 0.423 0.384

0.445 0.261 0.194 0.149 0.423 0.450 0.409

120 190 260 340 140 125 90

Adsorption at 60 °C.

Figure 3. Thermal decomposition of adsorbents in group 1 and group 2 during the temperature range of 200−600 °C. The adsorbent dosage is 10 mg, the heating rate is 9 °C/min, and the air flow rate is 20 mL/ min.

Figure 4. FT-IR spectra of the activated MIP1, MIP1a, MIP1b, and MIP1c, and MIP1b/CO2 adsorbing CO2.

at 200−300 °C in the work of Zelenak and at around 250 °C in recent study of Hao,9,22 and the weight loss of polymer-loaded mesoporous materials appeared at 150 °C in the work of Xu and at 220 °C in the work of Son.16,5 It can be seen from previous works that the thermo-stabilities of MIP-CO2 adsorbents are comparable to or even better than those adsorbents based on silica substrate. The FTIR spectra of activated MIP1, MIP1a, MIP1b, and MIP1c are displayed in Figure 4. The FTIR spectra of MIP2, MIP3 and NIP are identical to that of MIP1 due to the same chemical structure, and not given here. As shown in Figure 4, in FTIR spectra of all the adsorbents, N−H stretching vibration appears around 3440 cm−1; a sharp and strong peak at 1730 cm−1 may resulting from the overlap of N−H deformation vibration of amine group with CO stretching vibration; the absorption peaks at 1380 cm−1 and 1150 cm−1 are attributed to C−N stretching vibration. These results provided clear evidence that the amine group of AAM was reserved on the surface of all adsorbents after polymerization reaction. The peak intensities at around 3440, 1730, and ∼1150 cm−1 increase in order of MIP1, MIP1a, MIP1b, and MIP1c, which is due to an increase of amine content in polymers. Additionally, for all the adsorbents, the absorption peak of CC vibration is not observed in the area of 1660−1600 cm−1, suggesting that all CC bonds of AAM and EGDMA are broken, hence, no

AAM and EGDMA molecules are left in the polymers, from which, amine content can be evaluated according to the proportion of AAM in polymers. 3.2. CO 2 Adsorption Capacity and Mechanism Analysis. Figure 5 shows weight gain and evolution of heat led by CO2 capture on the adsorbents at 60 °C. It is apparent from Figure 5A that CO2 adsorption capacities increase almost linearly with time from 150 to 153 min. When the time increases from 153 min to 200 min, the CO2 adsorption capacities remain constant. This stable adsorption phase is considered as adsorption equilibrium one. CO2 desorption starts at 200 min, and complete desorption can be achieved within 6 min by flowing inert gas Ar at 60 °C. This suggests a weak interaction between CO2 and MIP adsorbents. The effects of various factors on CO2 adsorption capacities were investigated and the results are summarized in Table 2. For group 1 of Figure 5A, the CO2 adsorption capacities of MIP1, MIP2, MIP3, and NIP increase with SBET, Vp, and CO2/ N ratio, especially for SBET, suggesting that SBET is an important factor influencing CO2 adsorption capacity. For NIP, due to the lowest surface area resulting from the lack of template, its CO2 adsorption capacity is the lowest. Compared with MIP1, the three adsorbents in group 2 with the lower SBET exhibit the higher adsorption capacity, suggesting that SBET is not the only factor influencing CO2 1792



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Figure 5. TGA weight gain profiles during a CO2 adsorption/desorption cycle (A) and DSC heatflow profiles during adsorption process (B) of the adsorbents. The adsorption/desorption temperature is 60 °C.

formed after CO2 adsorption, again confirming that adsorption interaction between CO2 and the MIP-CO2 adsorbent is not a chemical reaction. We did a deep comparison with functionalized ITQ-6 in the work of Zukal,23 and found that the MIP-CO2 adsorbents had the advantage of time/energy saving in the preparation process of adsorbent. In addition, MIP adsorbent may benefit CO2 adsorption economically and highly effectively, due to the higher amine content and the larger pore size, and the lower adsorption enthalpy. To verify adsorption efficiency, the experiments of CO2 adsorption were carried out using MIP1b at 25 and 60 °C under 15% CO2/Ar atmosphere, and the data are given in Supporting Information (Figure S1). The results show that the adsorption capacity of CO2 is 0.912 mmol/g at 25 °C, and 0.478 mmol/g at 60 °C, indicating that the adsorption of CO2 is significantly affected by temperature. Compared with other works listed in Supporting Information (Table S1),9,17,22−27 the adsorption efficiency of CO2 is relatively high at 25 °C, although the SBET of adsorbent is relatively low, which may be due to the higher amine content in the adsorbent. Further research should be carried out to enlarge the SBET and improve the steric configuration of polymer by increasing the proportion of template, using the more effective porogenic agent, changing the template, monomer and crosslinker, and etc. Comparing with amine-grafted materials,17,24,28,29 the adsorption enthalpies of MIP-CO2 adsorbents are relatively lower, which might be because the adsorption force of amine site on CO2 is weakened by the electron cloud of cross-linked polymers, making them easier to regenerate during desorption process. Although other adsorbents, such as polythiophene− carbon mesocomposite and metal ion-exchanged zeolite,25,27,30−32 driven by electrostatic interaction to capture CO2, exhibited high CO2 capacity and low adsorption enthalpy, however, the selectivity was relatively low, and their stability still remains to be investigated. 3.3. Adsorption Selectivity and Stability. The selectivity of adsorbents was measured by the fixed bed equipment. The

adsorption capacity. From Table 2, it is clear that the amine contents of MIP1a, MIP1b, and MIP1c are much higher than that of MIP1, which may be due to an increase of proportion of AAM in polymerization system. Thus, the amine content is another significant influencing factor for adsorbing CO2. Because CO2 is an acidic gas, it can be absorbed by the basic amine active site on the surface of the MIP-CO2 adsorbents, which will be analyzed next. It is also found from Table 2 that CO2/N ratios of MIP1a, MIP1b, and MIP1c decrease significantly as an increase of amine content on the surface of adsorbents. The main reason is that the structure of adsorbent may be changed by increasing proportion of AAM in the polymer, resulting that a large number of amine active sites are not exposed on the pore surface but covered in the body of polymer, making CO2 unable to reach the active point due to the steric hindrance. Another reason is that the amount of CO2 molecules adsorbed on adsorbents in group 2 is affected by increasing pore size and decreasing surface area, leading to the decrease of CO2/N ratio in spite of high N content. That is why MIP1b, instead of MIP1c with highest amine content, becomes the adsorbent with the highest CO2 uptake. The DSC heatflow profiles during adsorption process are given in Figure 5B, and the adsorption enthalpies of adsorbents integrated from the DSC heatflow profiles are shown in Table 2. It can been seen from Table 2 that the calculated values of adsorption enthalpies are all below 40 kJ/mol which is in the range of the enthalpy of physical sorption, suggesting that the adsorption interaction between CO2 and the MIP-CO2 adsorbent is not chemical reaction but a type of intermolecular force or hydrogen bond. To further investigate the interaction between the absorbent and CO2, the FT-IR spectra of the absorbent following CO2 sorption were recorded, and the typical FT-IR spectra of MIP1b following CO2 sorption (denoted as MIP1b/CO2) is selected and shown in Figure 4. Compared with the FT-IR spectra of the activated MIP1b, the spectra of MIP1b/CO2 shows no obvious change expect for the disappeared weak peak at 2170 cm−1 resulting from the C≡N of the residual solvent AN, indicating that new bonds are not 1793



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calculated CO2 separation factors for all MIP-CO2 adsorbents were above 100 at the measuring conditions (see Table 2). The connection between the separation factor and the chemical and physical structure of polymers was not clear enough here and needs further research. In theory, the selectivity can be improved if the steric configuration of amine site fits well with the structure of CO2, and this target might be achieved by finding a proper way to avoid swelling in polymerization. Zhao and co-workers synthesized a series of porous silica-based adsorbent with amine-like motifs and observed a selectivity of CO2 between 10 and 50 at 1 atm.19 Pillai et al. studied the CO2 selectivity of microporous zeolite NaETS-4 and the reported selectivity was lower than 50.33 Xu et al. reported a new kind CO2 nanoporous “molecular basket” adsorbent with highselectivity more than 1000.15,16 Compared with these adsorbents, the selectivity of synthesized MIP-CO2 adsorbents is better than most of the porous silica-based adsorbents, but worse than the “molecular basket” adsorbents. Figure 6 depicts the dynamic adsorption capacity of MIP1b during 50 cycles of CO2 adsorption at 60 °C and desorption

under flowing N2 at 120 °C. The cyclical data reveal that the regeneration performance of MIP1b was fairly stable. The total adsorption capacity in the first run was 0.478 mmol (CO2)/g (MIP1b), and the final run produced a capacity of 0.468 mmol(CO2)/g(MIP1b), with only 2% drop in capacity after 50 adsorption/desorption cycles. The stability is comparable to that of the amine-grafted mesoporous silica materials.18,34

ASSOCIATED CONTENT

S Supporting Information *

SExperimental data of CO2 adsorption on MIP1b at 25 and 60 °C under 15% CO2/Ar atmosphere and a list of CO2 adsorption capacity on various adsorbents. This material is available free of charge via the Internet at http://pubs.acs.org.

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REFERENCES

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Figure 6. Adsorption capacity of MIP1b during 50 cycles of CO2 adsorption at 60 °C and desorption under flowing N2 at 120 °C.

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AUTHOR INFORMATION

Corresponding Author

*Phone: +86-0312-7522343; fax: +86-0312-7522192; e-mail: [email protected]..

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ACKNOWLEDGMENTS We appreciate the financial support of this research by the Major State Basic Research Development Program of China (973 Program, 2006CB200300-G). 1794



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Synthesis and CO2 Adsorption Properties of Molecularly Imprinted

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