Nano-structured MgO Sorbents Derived from Organometallic

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Environmental and Carbon Dioxide Issues

Nano-structured MgO Sorbents Derived from Organometallic Magnesium Precursors for Post-combustion CO2 Capture Yafei Guo, Chang Tan, Jian Sun, Weiling Li, Chuanwen Zhao, Jubing Zhang, and Ping Lu Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.8b00866 • Publication Date (Web): 14 May 2018 Downloaded from http://pubs.acs.org on May 15, 2018

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Nano-structured MgO Sorbents Derived from Organometallic Magnesium Precursors for Post-combustion CO2 Capture Yafei Guo, Chang Tan, Jian Sun, Weiling Li, Chuanwen Zhao*, Jubing Zhang, Ping Lu Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, School of Energy and Mechanical Engineering, Nanjing Normal University, Nanjing 210042, China *

Corresponding author:

Chuanwen Zhao, Tel.: +86-25-85481123, Fax: +86-25-85481124, E-mail: [email protected] ABSTRACT: Nano-structured MgO sorbents show promise for intermediate-temperature CO2 capture from post-combustion flue gas stream. However, their CO2 capture behaviors can be affected by the magnesium precursors applied for sorbent synthesis. To screen potential precursors for fabricating excellent CO2 trappers, MgO nanoparticles (NPs) were synthesized by calcining several organometallic precursors including magnesium ethoxide, magnesium acetate tetrahydrate, magnesium oxalate dehydrate, magnesium lactate dihydrate, magnesium citrate nonahydrate, and magnesium gluconate hydrate. The precursors and MgO NPs were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), N2 adsorption-desorption, field emission scanning electron microscopy (FESEM), and CO2-temperature programmed desorption (CO2-TPD). A fixed-bed reactor was used to evaluate the CO2 capture performances of the MgO NPs in a simulated flue gas stream. The effect of organometallic precursors on CO2 capture behaviors of the sorbents was further demonstrated. Results indicated that the different precursors would yield MgO NPs with distinct textural and surface properties, and these could further affect their CO2 capture behaviors. MgO NPs derived from magnesium oxalate dehydrate exhibited the highest CO2 uptake of 4.41 mmol CO2/g. The excellent CO2 uptake was mainly attributed to its superlative textural properties, uniform surface morphology and abundant base sites.

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1. INTRODUCTION The intensive CO2 emissions from fuel combustion process are associated with the aggravated global warming. Carbon capture, utilization and storage (CCUS) has been considered as the most effective option against others for short-term CO2 emission control to achieve the IEA 450 Scenario, since fossil fuels will remain the dominant position in global energy structure for the near term

1, 2

. CO2 capture as

the most crucial section in CCUS process has received extensive concerns, considering the fact that its capital cost accounts for 75% against the overall cost 3. The current available routes for CO2 capture process include pre-combustion CO2 capture 1, oxy-fuel combustion

4, 5

, and post-combustion CO2

capture 6. Taking into account the merits of low cost, high technical maturity, and good availability, post-combustion CO2 capture (PCC) has been regarded as a promising option for practical application 2. Thus, the key issue identified for PCC technology could be developing excellent CO2 sorbents 7. Inorganic solid sorbents have been given high priority while screening potential candidates for CO2 capture, due to the low energy consumption, better stability, and minimized environmental impact, as compared to the commercialized MEA solvent 8, 9. Depending on the different temperature windows for CO2 capture, the inorganic solid sorbents can be divided into three categories as the low-temperature sorbents (400oC, e.g. calcium-based sorbents and lithium-based materials)

, and

3, 15-21

.

Amongst various, intermediate-temperature MgO sorbent shows particular promise since it exhibits high capture capacity towards CO2 and low cost for raw materials in comparison to alkali metal-based sorbents, and it requires low energy loading for sorbent regeneration compared to calcium-based sorbents. Previous work indicated that MgO presented a high theoretical CO2 capture capacity, while the CO2 uptake of commercial bulk MgO could be low as 0.5 mmol CO2/g due to the limited base sites ACS Paragon Plus Environment

22, 23

.

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Besides, the carbonation process of MgO was kinetically controlled, and the reaction rate could be limited by its high lattice energy 24, 25. Thus, the principal problem for MgO sorbents is the limited CO2 uptake and reaction rate. To improve their CO2 capture performances, attempts such as optimizing the synthesis methods and fabricating nano-sized sorbents doped with alkaline metal eutectic mixtures have been made to enhance their textural and surface properties and to reduce the activation energy 26-30. One important approach to achieving such goals is to prepare porous MgO sorbents using different magnesium precursors. Precipitation, hydro-thermal and sol-gel methods have been widely adopted to fabricate highly efficient CO2 sorbents with improved textural properties and controlled surface morphologies 26, 27, 29, 31. However, these synthesis routes will consume massive costly raw materials and chemical additives. By contrast, solid state reaction process could be a facile, economic, and green route for sorbent development

28, 32

. Therefore, the direct pyrolysis or calcination of magnesium precursors

should be promising for facile preparation of MgO sorbents. The major concern for this method is to determine suitable magnesium precursors. Hence, it is critically necessary to illuminate the effect of magnesium precursors on the structure-property relationship of the MgO sorbents. CO2 capture performances of solid inorganic sorbents have been reported to be affected by their precursors. Liu et al. studied the precursor effect on CO2 capture behaviors of calcium-based sorbents. Nano-sized CaO particles were derived from different organic and inorganic calcium precursors. CO2 uptakes of the CaO sorbents could be depended on the precursors, since different precursors would yield samples with different textural and surface properties 33. Furthermore, the precursor effect had also been observed for porous MgO sorbents. Li et al. reported that MgO NPs derived from magnesium acetate tetrahydrate (Mg(Ac)2·4H2O) exhibited better textural properties and higher CO2 uptake than those originated from the calcination of magnesium nitrate hexahydrate (Mg(NO3)2·6H2O)

34

. Song et al.

prepared porous MgO sorbents from the pyrolysis of magnesium hydroxide (Mg(OH)2), basic magnesium carbonate (4MgCO3·Mg(OH)2), and magnesium oxalate (MgC2O4·2H2O)

35

. Precursors

played significant roles in regulating the physical properties and surface characteristics of the MgO ACS Paragon Plus Environment

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sorbents, and the precursor effect was further correlated to their CO2 capture behaviors 35. Furthermore, Choudhary et al., Aramend´ıa et al., and some others also reported that textural parameters of MgO catalysts would vary with the different magnesium precursors 36-39. To date, comprehensive reports concerning the precursor effect on the textural properties and CO2 capture performances of MgO sorbents are still limited. The majority of previous work have been focused on fabricating MgO sorbents from inorganic precursors, while Song’s contribution covers only two organometallic magnesium precursors. The effect of organometallic magnesium precursor on CO2 capture behaviors of MgO sorbents remains largely unclear. To this end, we synthesize MgO NPs from different organometallic precursors, and we thoroughly study the CO2 capture behaviors of these MgO NPs. The objective of the current work is to deepen the understanding of the precursor effect on the structure-property relationships of MgO sorbents, and therefore to screen the optimal precursor candidate for fabricating MgO NPs with excellent CO2 uptakes. The results will provide significant guidance for developing efficient solid CO2 sorbents. 2. EXPERIMENTAL SECTION 2.1 Materials and Synthesis Magnesium ethoxide (Mg(OC2H5)2, 98%), magnesium acetate tetrahydrate (Mg(Ac)2·4H2O, AR, 99.0%), magnesium citrate nonahydrate (Mg3(C6H5O7)2·9H2O, AR), and magnesium gluconate hydrate (Mg(C6H11O7)2·2H2O, USP) were purchased from Aladdin Industrial Corporation. Magnesium oxalate dehydrate (MgC2O4·2H2O, AR, 99.0%) was provided by Shanghai EKEAR Bio@Tech Co., Ltd. Magnesium lactate dihydrate (Mg(C3H5O3)2·2H2O, CP, 98%) was purchased from Nanjing Chemical Reagent Co., Ltd. All the organometallic magnesium precursors were used as received. The magnesium precursors of Mg(OC2H5)2, Mg(Ac)2·4H2O, MgC2O4·2H2O, Mg(C3H5O3)2·2H2O, Mg3(C6H5O7)2·9H2O, and Mg(C6H11O7)2·2H2O were labelled as ME, MA, MO, ML, MC, and MG, respectively. MgO sorbents were derived from the calcination of the different magnesium precursors in a muffle furnace


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under 500-600oC with a ramping rate of 10oC/min, and they were labelled as MgO-ME, MgO-MA, MgO-MO, MgO-ML, MgO-MC, and MgO-MG, respectively. 2.2 Characterization Thermogravimetric analysis (TGA) was performed on a thermo gravimetric analyzer (STA 449F3, NETZSCH, Germany) to study the thermal decomposition behaviors of the precursors. The precursors were decomposed in a pure N2 atmosphere under 800oC with a ramping rate of 10oC/min. N2 adsorptiondesorption tests were performed on an accelerated surface area and porosimetry analyzer (Tristar II ASAP 2020, Micromeritics, USA). The specific surface areas and pore volumes were calculated using the Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) methods, respectively. Surface morphologies of the MgO sorbents were observed on a field emission scanning electron microscope (SIRION 200, Philips, Netherlands). Crystalline structure of the sorbents were studied using an X-ray diffractometer (X’Pert PRO, Philips, Netherlands). CO2-temperature programmed desorption (CO2-TPD) experiments were performed on an automated chemisorption analyzer (Chembet Pulsar TPR/TPD, Quantachrome, USA) to identify the surface active sites. 0.5 g of the MgO sorbents were pretreated in a pure He flow (30 mL/min) at 300oC for 30 min. The sorbents were then cooled to 60oC, and the stream was switched to pure CO2 for adsorption. He stream was then switched to purge the system until the detected signal was stable. CO2 desorption tests were then performed by increasing temperature to 500oC with a heating rate of 10oC/min. 2.3 Sorbent Performance Measurement CO2 capture performances of the MgO sorbents were evaluated using a fixed-bed reactor. 0.05 g of the MgO sorbents were packed into the reactor. Prior to each test, the reactor was preheated to 200oC in a pure N2 flow to eliminate the adsorbed impurities. A simulated flue gas stream containing 10%CO2 and 90%N2 (100 mL/min) then flowed through the reactor for CO2 capture. Change of CO2 concentration at the outlet of the reactor was recorded by an online infrared gas analyzer. CO2 capture


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capacities were then calculated by integrating the outlet CO2 concentration curves using the same method as reported in our previous work 40. 3. RESULTS AND DISCUSSION 3.1 Phase Identification As the MgO NPs were calcined from the different precursors, phase transformation of the precursors would affect their physical properties. To reveal the phase transformation pathways, thermal decomposition behaviors of the different precursors were studied by TGA, and the results are shown in Fig. 1 and Table S1. Figure 1 Fig. 1 shows the TG and DTG profiles of the different organometallic magnesium precursors. TG profile of ME shows single weight loss step in 220-500oC, corresponding to the decomposition of ME precursor to MgO. The decomposition processes of MA and MO consist of two steps: the precursors firstly dehydrate below 300oC, and then the anhydrous crystals further decompose to form MgO in 300600oC. Three weight loss steps are observed for ML and MC, corresponding to the initial dehydration of the precursors, the intramolecular dehydration at higher temperature to form intermediates, and the transformation of intermediates to MgO NPs

41, 42

. MG presents typical multi-step thermal

decomposition pathways. The total weight losses of ME, MA and MO in TG tests are in line with the theoretical values, considering the complete decomposition of the precursors to MgO. However, those of ML, MC and MG show difference to the theoretical values. This might be ascribed to their complicated decomposition pathways. For the precursors with great molecular weight, the formed intermediates would decompose simultaneously under a narrow temperature range and a medium heating rate, and this might result in insufficient decomposition of the precursors. Mass changes of the precursors during calcination in the muffle conform well to the theoretical values, indicating the complete decomposition of the precursors under a sufficient holding time. During the thermal decomposition processes, gaseous


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products are evolved from the precursors, and this will yield MgO solids with porous structures and preferable textural properties. Figure 2 To further identify the crystalline structures of the solid sorbents, the calcined samples were examined by XRD, and the results are presented in Fig. 2. All the sorbents show repetitive diffraction peaks at the positions of 36.9o, 42.8o, 62.2o, 74.6o, and 78.5o, which are assigned as the (111), (200), (220), (311), and (222) lattice plane of the bulk MgO (PDF#45-0946) 23. No diffraction peaks for the precursors could be resolved in the XRD profiles, indicating that the precursors have been completely converted into MgO during the calcination process. The crystallite sizes of the sorbents are calculated from the (200) diffraction peak using the Scherrer equation, and they are ranked as: MgO-ME>MgO-MA>MgOMC>MgO-ML>MgO-MG>MgO-MO. 3.2 Textural Properties Figure 3 Fig. 3 shows the N2 adsorption-desorption isotherms of the MgO sorbents derived from different organometallic precursors. All these sorbents present typical Type IV isotherm with Type H3 hysteresis loop, according to the IUPAC classification

43

. The isotherms are featured by the initial monolayer

adsorption with low N2 uptakes in lower relative pressure range. N2 adsorption quantity then increases in higher relative pressure range, and the hysteresis loop presents due to the capillary condensation of N2 in mesopores. These indicate that the synthesized MgO sorbents are mesoporous materials with slit-shaped pores. N2 uptakes of MgO-MA, MgO-MC and MgO-MG are relatively low, while MgO-MO and MgOML show greater N2 adsorption quantities. MgO-ME presents the maximum N2 adsorption quantity, and this indicates better physical parameters. Figure 4 To further identify the pore features, pore size distributions of the sorbents are plotted in Fig. 4. All the sorbents show broad pore size distributions, and the majority of the pores are located in the pore ACS Paragon Plus Environment

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diameter range of 2-100 nm, indicating that the sorbents mainly contain mesopores. Particularly, MgOME should own a greater mesopore volume, as evidenced by the obvious changing rate of pore volume in 2-100 nm. Table 1 Textural parameters of the MgO sorbents are listed in Table 1. MgO-MA, MgO-ML, MgO-MC and MgO-MG show similar textural properties. Their BET surface areas and BJH pore volumes are in the ranges of 51.44-69.33 m2/g and 0.17-0.29 cm3/g. By contrast, MgO-MO possesses a higher BET surface area of 104.80 m2/g and a greater pore volume of 0.42 cm3/g. Amongst all these sorbents, MgO-ME exhibits the optimal textural properties with the maximum BET surface area (187.90 m2/g) and pore volume (0.71 cm3/g). The difference in textural properties amongst these sorbents might be associated with their CO2 capture behaviors. 3.3 Surface Characteristics Figure 5 FESEM images of the sorbents are depicted in Fig. 5. The decomposition of ME will produce uniform MgO NPs with medium particle size (Fig. 5a). By contrast, MA precursor will yield MgO NPs with relatively greater particle size, and the produced NPs then bond with each other to form aggregates (Fig. 5b). MgO derived from MO precursor shows smaller particle size, as shown in Fig. 5c. Precursors such as ML, MC, and MG are more likely to be decomposed into even smaller MgO NPs, as illustrated in Fig. 5d-f. These spherical nano-sized crystals, however, suffer severe sintering during the high-temperature calcination, as most of the NPs have been significantly agglomerated. The different morphological characteristics should be attributed to the decomposition pathways of the precursors. Generally, ME, MA, and MO with small molecular weight follow one or two-step decomposition mechanisms. The loss of crystal water occurs first at lower temperatures, and the formed anhydrous compounds further decompose into MgO at elevating temperatures. Whereas, the decomposition processes of ML, MC, and MG with larger molecular weight could be more complicated, which involve several steps as the loss of ACS Paragon Plus Environment

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crystal water, multi-stage intra-molecular dehydration, the formation of magnesium carbonate, and the formation of MgO particles. In particular, the multi-stage intra-molecular dehydration will lead to the agglomeration of NPs to form large blocks. This will further result in the decreased surface areas and pore volumes. Figure 6 In order to identify the CO2 adsorption sites of the different sorbents, CO2-TPD tests were performed and the results are shown in Fig. 6 and Table 2. For all these sorbents, three peaks can be resolved on the CO2-TPD profiles. This indicates that the sorbents contain three different base sites as the weak sites at the temperature below 200oC, the medium sites in the temperature range of 200-300oC, and the strong sites at the temperature beyond 300oC. The surface basicity could be quantified by calculating the area below the TPD profiles

35, 44

. The base sites for MgO-ME, MgO-MA, MgO-MO, MgO-ML, MgO-LC,

and MgO-MG are 0.66, 0.60, 0.67, 0.39, 0.42, and 0.53 mmol CO2/g, respectively. As shown in Table 2, the weak and medium sites in MgO-ME play predominant roles in the CO2 capture process, while the weak and strong sites dominant the CO2 capture process of MgO-MA. It is noticed that the weak sites could be the dominant sites for CO2 capture processes of MgO-MO, MgO-MC and MgO-MG. The weak, medium and strong sites in MgO-ML show comparable contribution towards CO2 capture, as the numbers of these sites are almost identical. The type, number and distribution characteristics of the active sites in these sorbents should be associated with their CO2 capture behaviors. Table 2 3.4 CO2 Capture Behaviors CO2 capture performances of the MgO sorbents were tested in a simulated flue gas stream of 10%CO2 and 90%N2 at 200oC using a fixed-bed reactor. Fig. 7a shows the dynamic CO2 breakthrough curves of the MgO sorbents against the adsorption time. The sorbents show rapid CO2 breakthrough processes with different breakthrough times, as an indicative of distinct CO2 capture capacities. An integration of the CO2 breakthrough curves further gives their total CO2 capture capacities. As illustrated ACS Paragon Plus Environment

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in Fig. 7b, CO2 capture capacities are calculated as 3.54, 2.48, 4.41, 1.87, 1.76, and 2.52 mmol CO2/g for MgO-ME, MgO-MA, MgO-MO, MgO-ML, MgO-MC, and MgO-MG, respectively. Figure 7 The difference in CO2 capture capacities is associated with the precursor effect. It is reported that different magnesium precursors will yield MgO NPs with distinct textural properties and surface characteristics during the calcination process 35. The variation in CO2 capture capacities of the MgO NPs derived from different precursors conforms well to the change of their textural and surface properties. Nano-sized sorbents such as MgO-ME and MgO-MO present higher CO2 uptakes, due to their higher surface areas, greater pore volumes and more active sites. Despite that MgO-MA shows poor textural properties, the sorbent possesses uniform surface morphology and considerable active sites, and these will contribute to relatively good CO2 capture capacity. By contrast, CO2 capture capacities of MgO-ML, MgO-MC and MgO-MG could be relatively low. This should be ascribed to the fact that the hightemperature calcination process has resulted in significant particle agglomeration, and this has further caused the reduction in surface area and pore volume, the deterioration of surface morphology and the loss of active sites. Figure 8 CO2 capture capacities of the MgO sorbents derived from organometallic magnesium precursors are compared to those of the MgO sorbents reported in literatures 22, 28, 32, 34, 35, 45-47. The results are presented in Fig. 8 and Table S2. CO2 capture capacities of the commercial bulk MgO and MgO powder were low as 0.23-0.45 mmol CO2/g, due to the limited porous structure and surface basicity

22

. To achieve

enhanced CO2 uptakes, inorganic magnesium precursors of Mg(OH)2, 4MgCO3·Mg(OH)2·4H2O and Mg(NO)3·6H2O were applied to fabricate MgO sorbents. CO2 capture capacities of these sorbents were in the range of 0.39-1.82 mmol CO2/g, depending on the different testing conditions

22, 32, 35, 45, 47

.

Organic magnesium precursors of Mg(Ac)2·4H2O and MgC2O4·2H2O were also employed to synthesize MgO sorbents with distinct CO2 capture capacities (0.66-1.38 mmol CO2/g) ACS Paragon Plus Environment

28, 34, 35

. CO2 capture

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capacities of the sorbents in this work are in the range of 1.76-4.41 mmol CO2/g. Particularly, MgO NPs derived from Mg(OC2H5)2 and MgC2O4·2H2O exhibit great CO2 uptakes (3.54 and 4.41 mmol CO2/g). The values could be higher than those of the MgO sorbents derived from 4MgCO3·Mg(OH)2·4H2O, Mg(NO)3·6H2O and MgC2O4·2H2O, as reported by Song et al., Ding et al., Elvira et al., Bhagiyalakshmi et al. and Li et al. 22, 28, 32, 35, 47. Therefore, organometallic precursors of Mg(OC2H5)2 and MgC2O4·2H2O could be promising candidates for facile fabrication of efficient CO2 sorbents. 4. CONCLUSION Several nano-sized MgO sorbents were facilely fabricated from the direct calcination of different organometallic magnesium precursors. The structure-property relationships of the as-synthesized MgO sorbents were illuminated by different characterization techniques. Textural properties and surface morphologies of the MgO NPs were depended on the precursors. Amongst the different MgO NPs, MgO-ME and MgO-MO possessed higher surface areas, greater pore volumes and more surface base sites. The effect of organometallic magnesium precursor on CO2 capture behaviors of the MgO sorbents was demonstrated. The difference in CO2 capture behaviors of the MgO sorbents were associated with their diverse textural properties and surface morphologies. MgO NPs derived from magnesium oxalate dehydrate (MgO-MO) showed the highest CO2 capture capacity of 4.41 mmol CO2/g and was therefore screened as the best candidate. The excellent CO2 capture performances could be ascribed to its good textural properties, uniform surface morphology, and superior surface basicity. An optimization of the calcination conditions to fabricate MgO NPs with enhanced CO2 capture capacity will be carried out in future work. Besides, the kinetics performances for CO2 capture of the as-synthesized sorbents deserve more efforts. Supporting Information Phase transformation of the different precursors during thermal decomposition and a summary of CO2 capture capacities of MgO sorbents derived from different magnesium precursors. ACS Paragon Plus Environment

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Notes The authors declare no competing financial interest. ACKNOWLEDGMENTS Financial support from the National Natural Science Foundation of China (U1510129 and 51706108), and the Natural Science Foundation of Jiangsu Province (BK20140926) is sincerely acknowledged.

REFERENCES 1. Wall, T. F., Combustion processes for carbon capture. Proceedings of the Combustion Institute 2007, 31, (1), 31-47. 2. Zhao, C.; Chen, X.; Anthony, E. J.; Jiang, X.; Duan, L.; Wu, Y.; Dong, W.; Zhao, C., Capturing CO2 in flue gas from fossil fuel-fired power plants using dry regenerable alkali metal-based sorbent. Progress in Energy and Combustion Science 2013, 39, (6), 515-534. 3. Liu, W.; An, H.; Qin, C.; Yin, J.; Wang, G.; Feng, B.; Xu, M., Performance enhancement of calcium oxide sorbents for cyclic CO2 capture-A review. Energy & Fuels 2012, 26, (5), 2751-2767. 4. Bu, C.; Gómez-Barea, A.; Leckner, B.; Chen, X.; Pallarès, D.; Liu, D.; Lu, P., Oxy-fuel conversion of sub-bituminous coal particles in fluidized bed and pulverized combustors. Proceedings of the Combustion Institute 2017, 36, (3), 3331-3339. 5. Buhre, B. J.; Elliott, L. K.; Sheng, C.; Gupta, R. P.; Wall, T. F., Oxy-fuel combustion technology for coal-fired power generation. Progress in Energy and Combustion Science 2005, 31, (4), 283-307. 6. Thiruvenkatachari, R.; Su, S.; An, H.; Yu, X. X., Post combustion CO2 capture by carbon fibre monolithic adsorbents. Progress in Energy and Combustion Science 2009, 35, (5), 438-455. 7. Samanta, A.; Zhao, A.; Shimizu, G. K.; Sarkar, P.; Gupta, R., Post-combustion CO2 capture using solid sorbents: a review. Industrial & Engineering Chemistry Research 2011, 51, (4), 1438-1463. 8. Wang, Q.; Luo, J.; Zhong, Z.; Borgna, A., CO2 capture by solid adsorbents and their applications: current status and new trends. Energy & Environmental Science 2011, 4, (1), 42-55. 9. Wang, J.; Huang, L.; Yang, R.; Zhang, Z.; Wu, J.; Gao, Y.; Wang, Q.; O'Hare, D.; Zhong, Z., Recent advances in solid sorbents for CO2 capture and new development trends. Energy & Environmental Science 2014, 7, (11), 3478-3518. 10. Zhang, B.-T.; Fan, M.; Bland, A. E., CO2 separation by a new solid K-Fe sorbent. Energy & Fuels 2011, 25, (4), 1919-1925. 11. Qin, C.; Yin, J.; Ran, J.; Zhang, L.; Feng, B., Effect of support material on the performance of K2CO3-based pellets for cyclic CO2 capture. Applied Energy 2014, 136, 280-288. 12. Bhatta, L. K. G.; Subramanyam, S.; Chengala, M. D.; Olivera, S.; Venkatesh, K., Progress in hydrotalcite like compounds and metal-based oxides for CO2 capture: a review. Journal of Cleaner Production 2015, 103, 171-196. 13. Li, Y. Y.; Wan, M. M.; Sun, X. D.; Zhou, J.; Wang, Y.; Zhu, J. H., Novel fabrication of efficient solid base: carbon-doped MgO-ZnO composite and its CO2 capture at 473 K. Journal of Materials Chemistry A 2015, 3, (36), 18535-18545. 14. Zhao, X.; Ji, G.; Liu, W.; He, X.; Anthony, E. J.; Zhao, M., Mesoporous MgO promoted with NaNO3/NaNO2 for rapid and high-capacity CO2 capture at moderate temperatures. Chemical Engineering Journal 2018, 332, 216-226. ACS Paragon Plus Environment

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15. Qin, C.; Liu, W.; An, H.; Yin, J.; Feng, B., Fabrication of CaO-based sorbents for CO2 capture by a mixing method. Environmental Science & Technology 2012, 46, (3), 1932-1939. 16. Sun, J.; Liu, W.; Hu, Y.; Wu, J.; Li, M.; Yang, X.; Wang, W.; Xu, M., Enhanced performance of extruded–spheronized carbide slag pellets for high temperature CO2 capture. Chemical Engineering Journal 2016, 285, 293-303. 17. Chi, C.; Li, Y.; Ma, X.; Duan, L., CO2 capture performance of CaO modified with by-product of biodiesel at calcium looping conditions. Chemical Engineering Journal 2017, 326, 378-388. 18. Li, Y.; Ma, X.; Wang, W.; Chi, C.; Shi, J.; Duan, L., Enhanced CO2 capture capacity of limestone by discontinuous addition of hydrogen chloride in carbonation at calcium looping conditions. Chemical Engineering Journal 2017, 316, 438-448. 19. Ji, G.; Memon, M. Z.; Zhuo, H.; Zhao, M., Experimental study on CO2 capture mechanisms using Na2ZrO3 sorbents synthesized by soft chemistry method. Chemical Engineering Journal 2017, 313, 646-654. 20. Xu, Y.; Ding, H.; Luo, C.; Zheng, Y.; Xu, Y.; Li, X.; Zhang, Z.; Shen, C.; Zhang, L., Effect of lignin, cellulose and hemicellulose on calcium looping behavior of CaO-based sorbents derived from extrusion-spherization method. Chemical Engineering Journal 2018, 334, 2520-2529. 21. Luo, C.; Zheng, Y.; Xu, Y.; Ding, N.; Shen, Q.; Zheng, C., Wet mixing combustion synthesis of CaO-based sorbents for high temperature cyclic CO2 capture. Chemical Engineering Journal 2015, 267, 111-116. 22. Bhagiyalakshmi, M.; Lee, J. Y.; Jang, H. T., Synthesis of mesoporous magnesium oxide: Its application to CO2 chemisorption. International Journal of Greenhouse Gas Control 2010, 4, (1), 51-56. 23. Liu, W.-J.; Jiang, H.; Tian, K.; Ding, Y.-W.; Yu, H.-Q., Mesoporous carbon stabilized MgO nanoparticles synthesized by pyrolysis of MgCl2 preloaded waste biomass for highly efficient CO2 capture. Environmental Science & Technology 2013, 47, (16), 9397-9403. 24. Zhang, K.; Li, X. S.; Chen, H.; Singh, P.; King, D. L., Molten salt promoting effect in double salt CO2 absorbents. The Journal of Physical Chemistry C 2015, 120, (2), 1089-1096. 25. Glasser, L.; Jenkins, H. D. B., Lattice energies and unit cell volumes of complex ionic solids. Journal of the American Chemical Society 2000, 122, (4), 632-638. 26. Han, K. K.; Zhou, Y.; Chun, Y.; Zhu, J. H., Efficient MgO-based mesoporous CO2 trapper and its performance at high temperature. Journal of Hazardous Materials 2012, 203-204, 341-347. 27. Li, P.; Liu, W.; Dennis, J. S.; Zeng, H. C., Synthetic architecture of MgO/C nanocomposite from hierarchical-structured coordination polymer toward enhanced CO2 capture. ACS Applied Materials & Interfaces 2017, 9, (11), 9592-9602. 28. Li, Y. Y.; Sun, X. D.; Dong, X. Y. M.; Wang, Y.; Zhu, J. H., Acquiring an Efficient Warm-CO2 Sorbent from Advanced Pyrolysis of Magnesium Oxalate. ChemNanoMat 2017, 3, (11), 822-832. 29. Wang, F.; Gunathilake, C.; Jaroniec, M., Development of mesoporous magnesium oxide– alumina composites for CO2 capture. Journal of CO2 Utilization 2016, 13, 114-118. 30. Wang, L.; Zhou, Z.; Hu, Y.; Cheng, Z.; Fang, X., Nanosheet MgO-Based CO2 Sorbent Promoted by Mixed-Alkali-Metal Nitrate and Carbonate: Performance and Mechanism. Industrial & Engineering Chemistry Research 2017. 56, (20), 5802-5812. 31. Luo, C.; Zheng, Y.; Ding, N.; Wu, Q.; Bian, G.; Zheng, C., Development and performance of CaO/La2O3 sorbents during calcium looping cycles for CO2 capture. Industrial & Engineering Chemistry Research 2010, 49, (22), 11778-11784. 32. Elvira, G.-B.; Francisco, G.-C.; Víctor, S.-M.; Alberto, M.-L. R., MgO-based adsorbents for CO2 adsorption: Influence of structural and textural properties on the CO2 adsorption performance. Journal of Environmental Sciences 2017, 57, 418-428. 33. Liu, W.; Low, N. W.; Feng, B.; Wang, G.; Diniz da Costa, J. C., Calcium precursors for the production of CaO sorbents for multicycle CO2 capture. Environmental Science & Technology 2009, 44, (2), 841-847. ACS Paragon Plus Environment

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34. Li, Y.; Wan, M.; Lin, W.; Wang, Y.; Zhu, J., A novel porous MgO sorbent fabricated through carbon insertion. Journal of Materials Chemistry A 2014, 2, (30), 12014-12022. 35. Song, G.; Zhu, X.; Chen, R.; Liao, Q.; Ding, Y. D.; Chen, L., Influence of the precursor on the porous structure and CO2 adsorption characteristics of MgO. RSC Advances 2016, 6, (23), 19069-19077. 36. Choudhary, V.; Rane, V.; Gadre, R., Influence of precursors used in preparation of MgO on its surface properties and catalytic activity in oxidative coupling of methane. Journal of Catalysis 1994, 145, (2), 300-311. 37. Aramendıa, M.; Borau, V.; Jimenez, C.; Marinas, J.; Porras, A.; Urbano, F., Magnesium oxides as basic catalysts for organic processes: study of the dehydrogenation–dehydration of 2-propanol. Journal of Catalysis 1996, 161, (2), 829-838. 38. Ruckenstein, E.; Hu, Y. H., The effect of precursor and preparation conditions of MgO on the CO2 reforming of CH4 over NiO/MgO catalysts. Applied Catalysis A: General 1997, 154, (1), 185-205. 39. Ruckenstein, E.; Wang, H., Partial oxidation of methane to synthesis gas over MgO-supported Rh catalysts: the effect of precursor of MgO. Applied Catalysis A: General 2000, 198, (1), 33-41. 40. Wang, P.; Guo, Y.; Zhao, C.; Yan, J.; Lu, P., Biomass derived wood ash with amine modification for post-combustion CO2 capture. Applied Energy 2017, 201, 34-44. 41. Zhang, J. J.; Ren, N.; Bai, J. H., Non-isothermal Decomposition Reaction Kinetics of the Magnesium Oxalate Dihydrate. Chinese Journal of Chemistry 2006, 24, (3), 360-364. 42. Szynkaruk, P.; Wesolowski, M.; Samson-Rosa, M., Principal component analysis of thermal decomposition of magnesium salts used as drugs. Journal of Thermal Analysis and Calorimetry 2010, 101, (2), 505-512. 43. Sing, K. S., Reporting physisorption data for gas/solid systems with special reference to the determination of surface area and porosity (Recommendations 1984). Pure and Applied Chemistry 1985, 57, (4), 603-619. 44. Han, S. J.; Bang, Y.; Kwon, H. J.; Lee, H. C.; Hiremath, V.; Song, I. K.; Seo, J. G., Elevated temperature CO2 capture on nano-structured MgO–Al2O3 aerogel: Effect of Mg/Al molar ratio. Chemical Engineering Journal 2014, 242, 357-363. 45. Ward, S. M.; Braslaw, J.; Gealer, R. L., Carbon dioxide sorption studies on magnesium oxide. Thermochimica Acta 1983, 64, (1), 107-114. 46. Zhao, Z.; Dai, H.; Du, Y.; Deng, J.; Lei, Z.; Shi, F., Solvo- or hydrothermal fabrication and excellent carbon dioxide adsorption behaviors of magnesium oxides with multiple morphologies and porous structures. Materials Chemistry & Physics 2011, 128, (3), 348-356. 47. Ding, Y. D.; Song, G.; Zhu, X.; Chen, R.; Liao, Q., Synthesizing MgO with a high specific surface for carbon dioxide adsorption. RSC Advances 2015, 5, (39), 30929-30935.


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Figure and table captions Fig. 1 Thermal decomposition behaviors of the different precursors (a) TG profiles; (b) DTG profiles Fig. 2 XRD patterns of the different MgO sorbents Fig. 3 N2 adsorption-desorption isotherms of the different MgO sorbents Fig. 4 Pore size distributions of the different MgO sorbents Fig. 5 FESEM images of the different MgO sorbents (a) MgO-ME; (b) MgO-MA; (c) MgO-MO; (d) MgO-ML; (e) MgO-MC; (f) MgO-MG Fig. 6 CO2-TPD profiles of the different MgO sorbents Fig. 7 CO2 capture behaviors of the different MgO sorbents (a) CO2 breakthrough curves; (b) CO2 capture capacities Fig. 8 CO2 capture capacities of MgO sorbents derived from different magnesium precursors Table 1 Textural Properties of the Different MgO Sorbents Table 2 Identification of the Active Sites in the Different MgO Sorbents


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ME MA MO ML MC MG

Weight, %

80

60

40

20

(a) 0

100

200

300

400

500

600

700

800

o

Temperature, C 0

Derivative weight, %/min

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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-2

ME MA MO ML MC MG

-4 -6 -8 -10

(b)

-12 0

10

20

30

40

50

60

70

Time, min

Fig. 1 Thermal decomposition behaviors of the different precursors (a) TG profiles; (b) DTG profiles


(222)

(311)

(200)

(220)

MgO-ME MgO-MA

Intensity, a.u.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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(111)

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MgO-MO MgO-ML MgO-MC MgO-MG 20

30

40 50 60 2 theta, degree

70

80

Fig. 2 XRD patterns of the different MgO sorbents


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120 MgO-ME

MgO-MA

400

90

300 60

N2 adsorption quantity, cm /g

200

3000 240

30

3

100

3

N2 adsorption quantity, cm /g

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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2000

MgO-MO

160

180

120

120 60 0 120

80 40

0 120

MgO-MC 90

G

MgO-MG

90

60

60

30

30

0 0.0

MgO-ML

0.2

0.4

0.6

0.8

1.0

0 0.0

0.2

Relative pressure, P/P0

0.4

0.6

0.8

Relative pressure, P/P0

Fig. 3 N2 adsorption-desorption isotherms of the different MgO sorbents


1.0

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MgO-ME MgO-MA MgO-MO MgO-ML MgO-MC MgO-MG

1.5 1.2

3

dV/dlogD, cm /g/nm

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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0.9 0.6 0.3 0.0 1

10 Pore diameter, nm

100

Fig. 4 Pore size distributions of the different MgO sorbents


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Fig. 5 FESEM images of the different MgO sorbents (a) MgO-ME; (b) MgO-MA; (c) MgO-MO; (d) MgO-ML; (e) MgO-MC; (f) MgO-MG


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MgO-ME

MgO-MA

TCD signal, a.u.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

MgO-MO

MgO-ML

MgO-MC

MgO-MG

100

200

400

300

500

o

Temperature, C

Fig. 6 CO2-TPD profiles of the different MgO sorbents


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1.0 Blank test MgO-ME MgO-MO MgO-MC

0.8 Dimensionless outlet CO2 concentration

0.6 0.4 0.2

1.0

100

200

300

MgO-MA MgO-ML MgO-MG

MgO-M E MgO-M A MgO-M O MgO-M L MgO-M C MgO-M G

0.8 0.6 0.4 0.2 0.0 0

50

100 Time, s

0.0 0

400

500

150

600

200

700

(a) 800

Time, s

5

CO2 capture capacity, mmol CO2/g

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Dimensionless outlet CO 2 concentration

Energy & Fuels

(b)

4 3 2 1 0

MgO-ME MgO-MA MgO-MO MgO-ML MgO-MC MgO-MG

Sorbents

Fig. 7 CO2 capture behaviors of the different MgO sorbents (a) CO2 breakthrough curves; (b) CO2 capture capacities


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5

CO2 capture capacity, mmol CO2/g

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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4

3

Bhagiyalakshmi et al. [22] Zhao et al. [46] Song et al. [35] Ward et al. [45] Ding et al. [47] Elvira et al. [32] Li et al. [34, 28] This work

This work

2

1

0

CM

MP

MH BMC MN

MA

MO

ME

Precursors

Fig. 8 CO2 capture capacities of MgO sorbents derived from different magnesium precursors CM: commercial available MgO; MP: MgO powder; MH: magnesium hydroxide; BMC: basic magnesium carbonate; MN: magnesium nitrate hexahydrate; MA: magnesium acetate tetrahydrate; MO: magnesium oxalate dehydrate; ME: magnesium ethoxide


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Table 1 Textural Properties of the Different MgO Sorbents Sorbents

Surface area a, m2/g

Pore volume b, cm3/g

Average pore size c, nm

Crystallite size d, nm

MgO-ME

187.90

0.71

15.17

32.84

MgO-MA

54.74

0.17

12.32

28.70

MgO-MO

104.80

0.42

24.14

23.84

MgO-ML

69.33

0.29

11.06

25.80

MgO-MC

68.67

0.18

10.67

25.97

MgO-MG

51.44

0.19

14.78

24.04

a

Surface area: multi-point BET surface area

b

Pore volume: single point adsorption total pore volume at P/P0=0.97

c

Average pore size: adsorption average pore width (4 V/A by BET)

d

Crystallite size: crystallite size calculated by the Scherrer equation based on the XRD results


Page 25 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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Table 2 Identification of the Active Sites in the Different MgO Sorbents Amount of CO2 desorbed, mmol CO2/g

Sorbents

o

Weak site, 300oC

Total

MgO-ME

0.31

0.23

0.12

0.66

MgO-MA

0.22

0.11

0.27

0.60

MgO-MO

0.36

0.16

0.15

0.67

MgO-ML

0.16

0.13

0.10

0.39

MgO-MC

0.24

0.12

0.06

0.42

MgO-MG

0.29

0.12

0.12

0.53


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Supporting Information Table S1 Phase transformation of the different precursors during thermal decomposition Table S2 A summary of CO2 capture capacities of MgO sorbents derived from different magnesium precursors


Nano-structured MgO Sorbents Derived from Organometallic

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