Unexpected highly reversible lithium silicates based CO2 sorbents

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Environmental and Carbon Dioxide Issues

Unexpected highly reversible lithium silicates based CO2 sorbents derived from sediment of Dianchi Lake Junya Wang, Taiping Zhang, ying yang, Min Li, Qingqing Qin, Peng Lu, Ping Ning, and Qiang Wang Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.8b02820 • Publication Date (Web): 04 Jan 2019 Downloaded from http://pubs.acs.org on January 4, 2019

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Unexpected highly reversible lithium silicates based CO2 sorbents derived from sediment of Dianchi Lake

Junya Wang1, Taiping Zhang1, Ying Yang1, Min Li1, Qingqing Qin3, Peng Lu2, Ping Ning1* Qiang Wang3

1Faculty

of Environmental Science and Engineering, Kunming University of Science

and Technology, Kunming, 650500, Yunnan, P. R. China. 2School

of Materials Science and Chemical Engineering, Ningbo University, Ningbo,

315211, Zhejing, P. R. China. 3College

of Environmental Science and Engineering, Beijing Forestry University, 35

Qinghua East Road, Haidian District, Beijing 100083, P. R. China.

*Corresponding author: Ping Ning Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500, Yunnan, P. R. China. E-mail: [email protected] Tel: +86 13708409187

1

ACS Paragon Plus Environment

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Abstract: In this work, Li4SiO4-based sorbents synthesized from sediment of Dianchi Lake for CO2 capture are reported first time. The sediment of Dianchi Lake was leaching treated with different ratios of hydrochloric acid (HCl) and nitric acid (HNO3), from which the obtained SiO2 was used for synthesis of Li4SiO4-based sorbents. The sorbents were all prepared by a solid-state reaction method using lithium nitrate (LiNO3, AR) and obtained SiO2, and their CO2 capture performances were determined by using a thermal gravimetric method by TGA analyzer. Influences of some important parameters such as pretreatment condition, synthesis condition and sorption condition on the CO2 uptake capacity of Li4SiO4-based sorbents were thoroughly investigated. The results showed that the sediment derived Li4SiO4 exhibited the largest CO2 uptake capacity of 27.93 wt%, reaching to 76 % of theoretical value of 36.70 wt%. More importantly, it showed outstanding cycling stability and superior regeneration ability in both temperature swing sorption and pressure swing sorption procedures, which will have the high potential for practical high temperature CO2 sorbent.

Key Words: CO2 sorbents, Li4SiO4, sediment, cycling stability

2


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1. Introduction With the rapid development of industrialization and the use of fossil fuels, emissions of carbon dioxide (CO2) into the atmosphere gradually increased1, 2. The global monthly average concentration of carbon dioxide (CO2) was above 400 ppm in March through May 20153. Energy-related CO2 emissions are the primary source of greenhouse gases (GHG) that lead to global climate change4. The control of GHG is arguably the most challenging environmental policy issue facing the world5. According to statistics, one third of CO2 emissions come from power plant flue gases6, 7.

To decreases the atmosphere of CO2, carbon capture and storage (CCS) technology

has received wide attention8. CCS is an important concept to reduce CO2 emissions, in particular from power plants9. The temperature of flue gases after combustion of fossil fuel usually ranges from 426.85 to 626.85 oC10. Thus, reducing the flue gas temperature to separating CO2 will result in the energy wasted of power plant11, 12. Therefore, to explore the high-temperature CO2 sorption material is necessary. After a long and unremitting effort, many kinds of high-temperature solid sorbents is available13,

14,

such as CaO-based materials15,

16,

CaSiO3 materials17,

lithium zirconate materials18 and lithium silicate materials6, etc.. Although, Ca-based sorbents exhibits high CO2 uptake capacity at high temperature (600-800 oC),but shows poor stability19. It is because that its capacity decreases dramatically after several sorption/desorption cycles and requires high energy for complete regeneration (950 oC)20. The main obstacle for the practical application of Li2ZrO3 is its kinetic limitation21. The theoretical CO2 uptake capacity of Li4SiO4 can reach up to 36.70 3


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wt%, which is much higher than that of lithium ceramics (Li2ZrO3) (up to 28.70 wt%)22. Among all these ceramics, lithium silicate (Li4SiO4) is considered as one of the most promising sorbents, because of the largest CO2 uptake capacity and the fastest CO2 uptake rate over a wide range of temperatures and CO2 concentrations23. Moreover, Li4SiO4 can absorb four or more times more CO2 than Li2ZrO3 during the first minutes24. Furthermore, Li4SiO4 has shown outstanding cyclability properties, which can be regenerated below 750 oC25, 26. From an economic point of view, the SiO2 is cheaper than ZrO227. The mechanism of Li4SiO4 adsorbing CO2 is usually explained by the double-shell theory. Suppose Li4SiO4 reacts with CO2 on the outer surface of the crystal grain; it is associated with ion diffusion to the surface of Li4SiO4 and reacts with Li+ and O2− on the surface to form Li2CO3 and Li2SiO322. Li2SiO3 forms a solid shell that covers unreacted Li4SiO4 and Li2CO328.With the increase in the double-shell thickness, the reaction proceeds under the diffusion control29. For Li4SiO4, many superior synthesis method have been proposed, including solid-state reaction method30, 31, co-precipitation method32, impregnation precipitation method33, and sol–gel method26. Among, them, the solid-state method is relative simple, and can obtained purity product34. B. N. Nair et al. considering the sol-gel method can synthesize nanoparticles and its large specific surface area could improve the CO2 sorption capacity35. However, Miriam J. Venegas showed that Li4SiO4 could not be obtained in pure form by the sol-gel route24. Among them, solid-state reaction method and the impregnation precipitation method have been proved that can produce pure Li4SiO436. Recent years, a lot of studies worked on using solid waste as raw 4


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materials to prepare CO2 sorbents.1,

37-39

The use of waste resource as the CO2

sorption sorbents not only offers the technology with competitive sorbent processing cost but also eliminates the waste simultaneously26, 40. So far, there are a few kinds of literature on the synthesis of Li4SiO4 from waste silicon-containing materials, which mainly include rice husk ash, fly ash, diatomite, and vermiculite1,

23, 41, 42.

The

research for application of sediment as the silicon source to synthesis Li4SiO4-based sorbents is a completely new synthesis route. Sediment is solid waste from the rivers and Lake43. Dianchi lake in the middle of the Yunnan-Guizhou Plateau of China44, receives drainage and effluents from 17 rivers and at least 20 springs and plays an important role for local socioeconomic activities45. In recent year, with the development of industry, more and more pollutants have been discharged into the Lake, causing serious pollution

46.

Studies

have shown that removing sediment from lakes can improve water quality, but the dredged sediment usually lack of effective utilization44. Recent years, many scholars have begun to study the effective utilization of sediment. Such as using sediment to make cement47, 48 and biochar49 etc.. Considering the significant content of SiO2 in sediment, in this paper, we first used the sediment from the Dianchi Lake as source of silica for fabrication of Li4SiO4-based CO2 sorbents. The influence of synthesis condition and sorption condition on the CO2 uptake capacity of synthesized Li4SiO4-based sorbents was thoroughly investigated. Finally, the sorption/desorption properties were investigated during the multiple cycling tests comparing with the pure SiO2 derived Li4SiO4 5


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sorbents. 2. Experimental Details 2.1 Sediment pretreatment The sediment of Dianchi Lake was obtained from Hubei Zhonggu Technology Co., Ltd. The sediment was firstly leaching treated three times in deionized water and drying at 105 oC in an oven prior. The chemical composition of obtained sediment samples was determined using (PANalytical Axios mAX) X-ray Fluorescence (XRF) spectrometer. The dried sediment sample was pretreated in 200 ml acid solution for 24 h at 80 oC.

6M different volume ratios of HCl and HNO3 are used for this treatment of

sediment. The volume ratios of HCl to HNO3 were denoted as “CN-x, x=1, 2, 3, 4,” and the obtained SiO2 samples were denoted as “SiO2-x, x=1, 2, 3, 4”. After leaching pretreatment by the acid, the suspension was centrifuged and washed several times with distilled water until the filter liquor PH = 7, then dried in an oven. The resultant solid powder was the silicon source, which main composition was SiO2, 2.2 Synthesis of Li4SiO4-base sorbents Li4SiO4 powders were prepared by a solid-state method using above obtained SiO2 sample and lithium nitrate (LiNO3, AR) in this study, according to the following reaction (1). The synthesis Li4SiO4 sample was denoted as “Li4SiO4-x-t, t=3, 4, 5, 8, 10”, where t indicates the molar ratio of Li to Si. The effects of Li:Si molar ratio (t = 3, 4, 5, 8 and 10), synthesis temperature (650 oC, 700 oC, 750 oC, 800 oC), and synthesis time (5, 6 and 7 h) of the synthesized sediment derived Li4SiO4 sorbents 6


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were further investigated. The whole flow charts for synthesis Li4SiO4 from sediment of Dianchi Lake is as illustration in Figure 1. SiO2 + 4LiNO3  Li4SiO4 + 4NO2 + O2

(1)

2.3 Sample characterization The structural of the sorbents were resolved by XRD on a Shimadzu XRD-7000 instrument with Cu Kα radiation. The XRD patterns were recorded with the range of 2θ = 5o - 80o. Specific surface area, pore volume and pore size distribution of synthesized Li4SiO4-based sorbents were tested by BET instrument (Tri star Ⅱ3000 sn: 1404) nitrogen (N2) adsorption analyzer. Scanning electron microscopy (SEM) analysis was performed using a (Nova Nano SEM 50) instrument. 2.4 Evaluation of CO2 capture performance The weight increase of Li4SiO4-based sorbents due to CO2 sorption was measured by using a thermogravimetric (TGA) analyzer (DTG-60H Instrument). Put 10 mg Li4SiO4-based sorbents into the sample pan of TGA, heat-treated from room temperature to test temperature in pure N2 and kept for 30 min. After that, the atmosphere was change to pure CO2 (40 ml/min) by N2 and kept for 120 min. The cycling stability and regenerability of Li4SiO4-based sorbents was also measured by TGA analyzer. Both temperature swing sorption (TSA) and pressure swing sorption (PSA) were used. For TSA, the CO2 sorption capacity was evaluated at 650 oC in pure CO2 for 30 min, while CO2 flow was 40 ml/min. Desorption capacity was evaluated at 750 oC in N2 for 30 min, while N2 flow was 20 ml/min. For PSA, the CO2 sorption capacity was evaluated at 650 oC/700 oC in pure CO2 for 30 7


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min and the CO2 desorption capacity was evaluated in N2 for 30 min at same temperature. 3. Results and discussion 3.1 Sorbent preparation and characterization The XRF results are given in Table 1. It can be seen that SiO2(42.09%), Al2O3(20.10%),

Fe2O3(13.05%),

CaO(7.28%),

TiO2(3.38%)

were

the

main

composition of sediment of Dianchi Lake, and another composition follows as Table 1. The XRF result shows that the major composition of sediment of Dianchi Lake is SiO2, which is suitable to be used as silicon source to produce Li4SiO4-based sorbents. The XRD pattern of raw sediment sample is given in Figure 2. The diffraction peaks are well matched to the characteristic diffraction patterns of JCPDS file 46-1045. The XRD pattern confirmed that their majority phase was crystalline silicon. As shown in Figure 2, the XRD pattern of the raw sediment showed the characteristic diffraction peaks of SiO2 (2θ = 26.66o)，Al2O3 (2θ = 35.15o), Fe2O3 (2θ = 56.12o) and CaCO3 (2θ = 29.38o). To get pure SiO2, the sediment was firstly leaching treated in the acid solution for 24 h at 80 oC. The acid solution was 6M HCl and HNO3 with different volume ratios. The weight of obtained solid powders was listed in Table 2. Four different volume ratio of acid including 6M CN-1, CN-2, CN-3, CN-4 were used. From the experimental results, it can be seen that the volume ratio of HCl to HNO3 used for the leaching treatment affected the quality of the obtained SiO2 sample. The results showed that the weight of solid powder increased with the increase of the proportion 8


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of HCl. From the XRD results, after acid leaching treatment, the peak of Fe2O3 and CaCO3 was disappeared (see Figure 3). Compared with original sample (Figure 2), other impurities peaks were significantly reduced. However, the peak of Al2O3 (2θ = 35.15) still exists. The XRD results suggested that acid leaching treatment can remove and reduce the other compositions in the sediment to obtain SiO2. To explore the influence of different acid treatment conditions on CO2 sorption performance, Li4SiO4-based sorbents were synthesized with the molar ratio of Li:Si was 4 and 5, and then the sorbents were calcined at 750 oC for 6 h. The CO2 sorption performance was evaluated at 650 oC. Figure 4 and Figure 5 shows the CO2 uptake capacity of Li4SiO4-x-4 and Li4SiO4-x-5 sample synthesized at 750 oC for 6 h. From Figure 4, when x increased from 1 to 3, the CO2 sorption capacity of Li4SiO4-x-4 increased by the first 30 min. However, with the sorption time going up, the sorption rate of Li4SiO4-2-4 was growing quite fast, and got the maximum value of 27.93 wt%. When the Li:Si = 5, nearly the same trend as its sorption capacity can be seen in Figure 5. Li4SiO4-2-5 and Li4SiO4-3-5 nearly got the maximum value at the same time (27.42 and 27.10 wt%). These results indicated that different acid pretreatment will change the sediment composition, influencing Li4SiO4 production (amount and microstructural properties). Combined with XRD images of different acid treatment (see Figure 3), exist of Al2O3 will greatly enhanced the CO2 sorption capacity of synthesized Li4SiO4 samples. Therefore, considering the comprehensive performance, we choose 6M HCl and HNO3 with the molar ratio of 2 to 1 (CN-2) as the acid 9


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treatment condition. 3.2 CO2 sorption performance Besides the influence of the acid leaching treatment, in order to obtain the best Li4SiO4-based sorbent, Li:Si molar ratio is another important factor. In this research, the Li4SiO4-based sorbents in different Li:Si molar ratio (Li:Si = t, t = 3, 4, 5, 8, 10) were synthesized by using SiO2 sample, which was obtained from sediment treated with 6M CN-2 as silicon source. All resultant sorbents were calcined at 750 oC for 6 h and evaluated at 650 oC for 120 min in pure CO2. From Figure 6, it can be seen that the molar ratio of Li:Si = 3, the CO2 uptake capacity was relatively low, reaching 12.05 wt %. When the Li:Si molar ratio was 4 and 5, the CO2 uptake capacity sharply improved to 27.93 wt % and 27.42 wt %, respectively. However, increasing the Li:Si molar ratio to 8 and 10, the CO2 sorption capacity sharply decreases to 11.40 wt% and 16.89 wt%, respectively. Figure 7 and Figure 8 show the XRD and BET results of Li4SiO4-based sorbents synthesized using different Li:Si molar ratio. It can be seen that the characteristic peaks of Li4SiO4 were detected in all samples in Figure 7, indicating that Li4SiO4 could be produced by synthesis of different Li:Si molar ratio. However, when Li:Si = 3, the characteristic peaks of Li2SiO3 were detected. It has been reported that at high temperature, the Li2SiO3 has no CO2 uptake capacity41. Therefore, the sample showed low CO2 sorption capacity at Li:Si = 3. When the Li:Si molar ratio was 4 and 5, pure Li4SiO4 was synthesized, the CO2 sorption capacity reached maximum value of 27.93 wt% and 27.42 wt%. With the molar ratio of Li:Si = 8, the characteristic peaks of 10


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Li3HSiO4 and LiOH (2θ = 33.44o, 2θ = 33.54o) appeared. When the molar ratio of Li:Si = 10, small portion of Li2O (2θ = 33.61o), LiOH and Li3HSiO4 were detected. It was reported that Li2O has poor cycling performance and is not suitable for practical application41,

50.

Figure 8 is the Li4SiO4-2-4 N2 adsorption/desorption isothermal

diagram. It can be seen that the isotherm of Li4SiO4-2-4 was type Ⅲ with hysteresis loops. The results indicated that the Li4SiO4-2-4 sorbent was non-porous; this result is consistent with previous studies32. Table 3 shows BET surface area, BJH pore volume and BJH pore size of Li4SiO4-2-t (t = 3, 4, 5, 8, 10). When the molar ratio of Li:Si = 4, its specific surface area was relative higher (14.3461 m2/g) than other samples. Considering the sorption capacity and cycle performance, Li4SiO4-2-4 sample will be further studied. The synthesis temperature often greatly affects the CO2 sorption performance of Li4SiO4-based sorbent. To explored the effect of synthesis temperature for Li4SiO4-based sorbents on the CO2 sorption performance. Li4SiO4-2-4 samples were calcined for 6 h at different temperatures (650 ， 700 ， 750 and 800 oC). The CO2 sorption capacity evaluated condition was 650 oC for 120 min. As seen in Figure 9, the CO2 sorption capacity rapidly increased from 19.32 wt% to 27.93 wt% with the synthesis temperature increased from 650 to 750 oC. However, with the synthesis temperature further increased, the CO2 sorption capacity started to decrease. When the synthesis temperature reached at 800 oC，the CO2 sorption capacity decreased to 15.12 wt%. Although, the best CO2 sorption capacity occurred on the synthesis temperature of 750 oC, the sorption rate increases slowly. Nevertheless, when the synthesis 11


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temperature was 700 oC, the CO2 sorption capacity quickly reached sorption equilibrium within 30 min and got its highest capacity of (25.76 wt %) after 120 min. These results indicated that the synthesis temperature had significant influence on CO2 capture capacity, and the sample synthesized at 700 oC had the best sorption efficiency. Furthermore, synthesis (calcination) time is another important factor that can influence the CO2 sorption performance. Therefore, the Li4SiO4-2-4 samples were synthesized (calcined) at 750 oC in muffle furnace for 5, 6 and 7 h, respectively. As seen in Figure 10, the CO2 sorption capacity of Li4SiO4-2-4 sorbents synthesized at 5 h and 7 h is very similar, which was 24.08 wt% and 23.41 wt%, respectively. However, when the calcination time of the sample was 6 h, its CO2 sorption capacity can reach the maximum value (27.93 wt%). The experimental results confirmed that an optimized synthesis time was 6 h. In addition to synthesis temperature and synthesis time, the operation condition was also needed to be optimized. Therefore, the CO2 sorption capacity of Li4SiO4-2-4 sample under different sorption temperature was evaluated, which results are shown in Figure 11. At 600 oC, its CO2 sorption capacity (20.08 wt%) was lower than that of 650 and 700 oC. The sorption temperature was further increased to 650 and 700 oC, the CO2 sorption capacity of the Li4SiO4-2-4 samples was increased to 27.93 and 26.32 wt%, respectively. The results showed that the sample got the maximum CO2 uptake capacity at the temperature of 650 oC, however, at 700 oC, the CO2 sorption capacity quickly reached sorption equilibrium within 10 minutes and got its highest 12


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capacity, which indicated that the sample had a very fast sorption rate at 700 oC. At 750 oC, the Li4SiO4-2-4 sorbent showed a low CO2 sorption capacity (3.80 wt%). This may be due to the high temperature leads to the sintering of Li4SiO4 and loss its CO2 sorption capacity. A double exponential model was successfully used to simulate two different processes taking place during CO2 sorption on Li4SiO4, chemisorption and lithium diffusion. This model is represented as: y = Aexp-k1t + Bexp-k2t + C In this formula, y presents sorption capacity; t is sorption time, A, B and C is the pre-exponential factors; k1 is the exponential constants for CO2 chemisorption on the sorbent surface and k2 is the CO2 chemisorption rate controlled by lithium diffusion. Figure 11 presents the isotherms of Li4SiO4 sorbents at different sorption temperature. The parameters obtained are presented in Table 4. At 600, 650 and 750 oC, the value of k1 were one order of magnitude large than the k2 values. The results clearly indicated that diffusions were the main factor limiting the process of whole CO2 capture. This conclusion is consistent with the results of literatures34, 51. 3.3 Cycling stability test For high temperature CO2 sorbent, the stability of CO2 sorption/desorption cycling is also a crucial factor. In order to obtain the relevant data of the synthesized Li4SiO4 sorbent in the view of long cyclic working capacity and lifetime, the cycling stability of Li4SiO4-2-4 samples was investigated. The cycling performance of Li4SiO4-2-4 sorbents was measured using typical TSA and PSA procedures. And in order to provide a base case for comparison, pure SiO2 derived Li4SiO4 (Li4SiO4-P) sample 13


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was prepared following the same conditions in this work. Both TSA and PSA procedures were operated at sorption for 30 min and desorption for 30 min. For TSA, the sorption was evaluated at 650 oC with 100% CO2 (40 ml/min), while desorption was performed at 750 oC with 100% N2 (20 ml/min). Figure 12 (a) and (b) shows the results of TSA procedure. For Li4SiO4-2-4 sorbent (see Figure 12(a)), the CO2 sorption capacity reached 21.08 wt% at the 1st cycle. With an increase in cycle number, the CO2 sorption capacity from its initial 21.08 wt% gradually decreased to 14.14 wt% from 1st to 13th cycle. However, the CO2 sorption capacity had small change from 14th to 22th cycles and reached a final CO2 uptake of (12.50 wt%). Figure 12(b) shows the sorption/desorption results of the Li4SiO4-P under the same conditions. Although, the CO2 uptake capacity gradually increased from the 1th to the 22th cycle, the capacity only increased from its initial 2.90 wt% to 4.44 wt%. It clearly indicated that the Li4SiO4-2-4 sample had higher CO2 sorption capacity than Li4SiO4-P during the 22 cycles. Considering the process of temperature change maybe results complicated in practical application and will cost the energy, the PSA process was studied in this study. For PSA, from the result of Figure 11, it shows that the Li4SiO4-2-4 sample had the fast sorption rate at the sorption temperature of 700 oC, and got the maximum CO2 sorption value at the sorption temperature of 650 oC. Therefore, in the PSA process, two experiments were done with the sorption and desorption temperature setting at 650 and 700 oC, respectively. And the sorption and desorption time were also setting at 30 min, respectively. PSA results of 650 oC are shown in Figure 12(c) and (d). It 14


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can be seen that it was very stable during the first 6 cycles of the Li4SiO4-2-4 sample. From 7th cycle, the CO2 sorption capacity of the sorbents started to decrease slightly and the final CO2 capture capacity was (14.51 wt%) at 22th cycle (see Figure 12(c)). Although, the Li4SiO4-P showed the increasing CO2 sorption capacity in the first 3 cycle in PSA results, from the 4th cycle, its CO2 sorption capacity decreased shapely and its CO2 sorption capacity was only 2.05 wt% at 22th cycle (see Figure 12(d)). Figure 12(e) and (f) shows the PSA results of 700 oC. The CO2 uptake capacity of the Li4SiO4-2-4 sample gradually increased from the 1th to the 6th cycle and then nearly no change (see Figure 12(e)). However, for Li4SiO4-P, Figure 12(f) clearly shows that the CO2 uptake capacity increased slowly from the 1th cycle and got the CO2 uptake of 8.54 wt% at 22th cycle. As shown in Figure 12 (e) and (f), after 22 CO2 sorption/desorption cycles at 700 oC,

with the increasing of cycle times, the CO2 sorption capacity of Li4SiO4-2-4

sample and Li4SiO4-P sample increased gradually. Table 5 summaries of Li4SiO4 materials and their CO2 capture cycle performance in recent years. Obviously, it can be found that the CO2 sorption capacity gradually decreases or is relatively stable with the increase of cycle times. With the increasing of cycle times, the CO2 sorption capacity increased rarely. Therefore, the sediment as a silicon source to synthesize Li4SiO4-based sorbents has good application value. To investigate the reason why CO2 sorption capacity of Li4SiO4-2-4 sorbent increased with the increasing number of cycle in PSA 700 oC process, the SEM analysis was used to characterize the morphology changes of Li4SiO4-based sorbents 15


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before and after sorption (see Figure 13). In Figure 13(a) and (f), it can clearly be seen that the surface of raw Li4SiO4-2-4 sample seems rough and exhibited dense polygonal particles, mainly ranging from 4 -13 μm. However, the surface of raw Li4SiO4-P sample seems smooth and the particle size was between 8 and 20 μm. The particle size of raw Li4SiO4-2-4 was much smaller than that of raw Li4SiO4-P sample, which may resulted in the better CO2 sorption capacity.52 Moreover, the Li4SiO4-2-4 sample and Li4SiO4-P sample after cycle 1, cycle 6, cycle 12 and cycle 22 were analyzed using SEM. From Figure 13(b), after 1 sorption/desorption cycle, the surface of Li4SiO4-2-4 sample was rough and it displayed a dispersed particle. There was no significant change from the sample before sorption, as seen Figure 13(a). After 6 and 12 sorption/desorption cycles, the particles of Li4SiO4-2-4 sample presented a local particle agglomerate, and there were gaps between the agglomerated particles, as shown in Figure 13(c) and (d). As shown in Figure 13(e), after 22 sorption/desorption cycles, although the Li4SiO4-2-4 sample showed particles agglomeration, the gaps also existed. The existence of gaps may promote the rapid diffusion of CO2 to the surface of Li4SiO4, which increases the sorption capacity. This conclusion is consistent with the idea that well-development pore structure can promote CO2 capture proposed by Wang et al53. For comparison, the surfaces of Li4SiO4-P sample were smooth but shown closely polygonal particles after 1, 6 and 12 sorption/desorption cycles, as shown in Figure 13(g), (h) and (i). After 22 sorption/desorption cycles, the surface of Li4SiO4-P sample changed from smooth to rough and presented a local particle agglomeration with gaps, as shown in Figure 16


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13(j). Therefore, the enhancement in CO2 capture performance of the Li4SiO4-2-4 sample and Li4SiO4-P sample during the cycling test in PSA 700 oC maybe attributed to the morphological changes in the sorption/desorption processes. In addition, the Li4SiO4-2-4 sample showed higher sorption capacity during the cycling test in PSA 700 oC than the Li4SiO4-P sample, which can also attributed to morphology and its particle size. For CO2 sorbents, in addition to CO2 capture capacity and sorption rate, the desorption rate is also very crucial for their practical application. Therefore, in order to further implore the CO2 desorption rate of synthesized Li4SiO4 sorbents, one sorption/desorption cycle in each sorption and desorption cycle was selected for study, which results are shown in Figure 14. In TSA procedure, both of the Li4SiO4-2-4 sample and Li4SiO4-P sample can be completely desorption in N2 within 10 min (see Figure 14(a) and (b)). In PSA procedure, when the evaluated temperature was 650 oC, the Li4SiO4-2-4 sample and Li4SiO4-P sample had the nearly the same CO2 desorption rate, which can reach 95.3% and 96.8%, respectively at the first 5 min. With desorption time increasing, the CO2 desorption rate of the Li4SiO4-2-4 sample grew a little quickly than Li4SiO4-P sample. At 15 min, the CO2 desorption rate Li4SiO4-2-4 sample and Li4SiO4-P sample was 99.1% and 98.3%, respectively. When the desorption reach 30 min, both of them can be fully desorption. As shown in Figure 14(e) and (f), when the evaluated temperature was 700 oC, the CO2 could be completely desorption from Li4SiO4-2-4 sample within less than 5 min, which showed very highly desorption rate. However, for Li4SiO4-P sample, it needed 12 min to 17


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complete the fully desorption. Nevertheless, these results indicated that the synthesized sediment derived Li4SiO4-2-4 sorbents not only have high sorption capacity, but also have fast desorption rate. In summary, the results of cycling tests demonstrated that our synthesized sediment derived Li4SiO4-2-4 sorbents have a much higher reversible CO2 capture capacity than that of pure SiO2 derived Li4SiO4 in both TSA and PSA procedures, which has the high potential for practical high temperature CO2 capture.

4. Conclusions In this work, we presented a Li4SiO4-based sorbents prepared from sediment of Dianchi Lake for the first time. The acid treatment condition, Li:Si molar ratio, synthesis temperature and synthesis time all showed significant effect on the CO2 sorption performance of sediment derived Li4SiO4-based sorbents. At Li:Si = 4, synthesis temperature was 750 oC and synthesis time was 6 h, pure Li4SiO4 was synthesized, showing the largest CO2 sorption value of 27.93 wt%, reaching to 76% of theoretical sorption value of 36.70 wt%. The results of cycling tests demonstrated that the sediment derived Li4SiO4 sorbents have a much higher reversible CO2 capture capacity than that of pure SiO2 derived Li4SiO4 in both TSA and PSA procedures. Surprisingly, the sediment derived Li4SiO4 sorbents not only have high sorption capacity, but also have fast desorption rate. The CO2 can be completely desorption from Li4SiO4-2-4 sample within less than 5 minutes at 700 oC. Since the sediment derived Li4SiO4 sorbents showed high sorption capacity, fast desorption rate, superior 18


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cycling stability and excellent regeneration ability, it is believed that they will be very promising high-temperature CO2 sorbents.

Acknowledgements We are very grateful to the National Natural Science Foundation of China (21868015, 51802135, 51568067, 51622801 and 51572029) and the Scientific Researching Fund Projects of Yunnan Provincial Department of Education (2017ZZX137), which funded this study. We are also grateful to all member units of the project team for their help.

References (1). Shan, S. Y.; Jia, Q. M.; Jiang, L. H.; Li, Q. C.; Wang, Y. M.; Peng, J. H., Preparation and kinetic analysis of Li4SiO4 sorbents with different silicon sources for high temperature CO2 capture. Chin. Sci. Bull. 2012, 19, 2475-2479. (2). Zhao, D.; Sheng, G.; Hu, J.; Chen, C.; Wang, X., The adsorption of Pb(II) on Mg2Al layered double hydroxide. Chem. Eng. J. 2011, 171, 167-174. (3). Corinne, L. Q.; Robbie, M. A.; Josep, G. C.; S.;, S., Global Carbon Budget 2016. Earth Syst. Sci. Data 2016, 8, 1-45. (4). Wang, H.; Ang, B. W.; Zhou, P., Decomposing aggregate CO2 emission changes with heterogeneity: an extended production-theoretical approach. Energy J. 2018, 39, 59-79. (5). Rao, A. B.; Rubin, E. S., A technical, economic, and environmental assessment of amine-based CO2 capture technology for powerplant greenhousegas control. Environ. Sci. Technol. 2002, 36, 4467-4475. (6). Kato, M.; Nakagawa, K.; Essaki, K.; Maezawa, Y.; Takeda, S.; Kogo, R.; Hagiwara, Y., Novel CO2 absorbents using Lithium-containing oxide. Int. J. Appl. Ceram. Tec. 2005, 2, 467-475. (7). Gao, Y.; Zhang, Z.; Wu, J.; Yi, X.; Zheng, A.; Umar, A.; O'Hare, D.; Wang, Q., Comprehensive investigation of CO2 adsorption on Mg–Al–CO3 LDH-derived mixed metal oxides. J. Mater. Chem. A 2013, 1, 12782-12790. (8). Romeo, L. M.; Lara, Y.; Lisbona, P.; Martínez, A., Economical assessment of competitive enhanced limestones for CO2 capture cycles in power plants. Fuel Process. Technol. 2009, 90, 803-811. (9). Feron, P. H. M.; Hendriks, C. A., CO2 capture process principles and costs. Oil. Gas. Sci. Technol. 2006, 60, 451-459. (10). Ochoafernández, E.; Rønning, M.; Grande, T.; Chen, D., Synthesis and CO2 capture properties of nanocrystalline Lithium Zirconate. Chem. Mater. 2006, 18, 6037-6046. (11). Ida, J. I.; Lin, Y. S., Mechanism of high-temperature CO2 sorptionon Lithium Zirconate. Environ. 19


Energy & Fuels 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

Sci. Technol. 2003, 37, 1999-2004. (12). Khomane, R. B.; Sharma, B. K.; Saha, S.; Kulkarni, B. D., Reverse microemulsion mediated sol–gel synthesis of lithium silicate nanoparticles under ambient conditions: Scope for CO2 sequestration. Chem. Eng. Sci. 2006, 61, 3415-3418. (13). Adelodun, A. A.; Lim, Y. H.; Jo, Y. M., Surface oxidation of activated carbon pellets by hydrogen peroxide for preparation of CO2 adsorbent. J. Ind. Eng. Che. 2014, 20, 2130-2137. (14). Rabiee, H.; Meshkat, A. S.; Soltanieh, M.; Mousavi, S. A.; Ghadimi, A., Gas permeation and sorption properties of poly(amide-12-b-ethyleneoxide)(Pebax1074)/SAPO-34 mixed matrix membrane for CO2/CH4 and CO2/N2 separation. J. Ind. Eng. Chem. 2015, 27, 223-239. (15). Chanburanasiri, N.; Ribeiro, A. M.; Rodrigues, A. E.; Arpornwichanop, A.; Laosiripojana, N.; Praserthdam, P.; Assabumrungrat, S., Hydrogen production via sorption enhanced steam methane reforming process using Ni/CaO multifunctional catalyst. Ind. Eng. Chem. Res. 2011, 50, 13662-13671. (16). Oliveira, E. L. G.; Grande, C. A.; Rodrigues, A. E., CO2 sorption on hydrotalcite and alkali-modified (K and Cs) hydrotalcites at high temperatures. Sep. Purif. Technol. 2008, 62, 137-147. (17). Wang, M.; Lee, C.-G., Absorption of CO2 on CaSiO3 at high temperatures. Energ. Convers. Manage. 2009, 50, 636-638. (18). Xiong, R.; Ida, J.; Lin, Y. S., Kinetics of carbon dioxide sorption on potassium-doped lithium zirconate. Chem. Eng. Sci. 2003, 58, 4377-4385. (19). Amorim, S. M.; Domenico, M. D.; Dantas, T. L. P.; José, H. J.; Moreira, R. F. P. M., Lithium orthosilicate for CO2 capture with high regeneration capacity: Kinetic study and modeling of carbonation and decarbonation reactions. Chem. Eng. J. 2016, 283, 388-396. (20). Yin, X. S.; Song, M.; Zhang, Q. H.; Yu, J. G., High-temperature CO2 capture on Li6Zr2O7 : experimental and modeling studies. Ind. Eng. Chem. Res. 2010, 49, 6593-6598. (21). Wang, Q.; Luo, J.; Zhong, Z.; Borgna, A., CO2 capture by solid adsorbents and their applications: current status and new trends. Energ. Environ. Sci. 2011, 4, 42-55. (22). GAUER, C.; HESCHEL, W., Doped lithium orthosilicate for absorption of carbon dioxide. J. Mater. Sci. 2006, 41, 2405-2409. (23). Sanna, A.; Ramli, I.; Maroto-Valer, M. M., Development of sodium/lithium/fly ash sorbents for high temperature post-combustion CO2 capture. Appl. Energ. 2015, 156, 197-206. (24). Venegas, M. J.; Fregoso-Israel, E.; Escamilla, R.; Pfeiffer, H., Kinetic and reaction mechanism of CO2 sorption on Li4SiO4 : study of the particle size effect. Ind. Eng. Chem. Res. 2007, 46, 2407-2412. (25). Kimura, S.; Adachi, M.; Noda, R.; Horio, M., Particle design and evaluation of dry CO2 recovery sorbent with a liquidholding capability. Chem. Eng. Sci. 2005, 60, 4061-4071. (26). Olivares-Marín, M.; Drage, T. C.; Maroto-Valer, M. M., Novel lithium-based sorbents from fly ashes for CO2 capture at high temperatures. Int. J. Greenh. Gas Con. 2010, 4, 623-629. (27). 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. Energ. Environ. Sci. 2014, 7, 3478-3518. (28). Seggiani, M.; Puccini, M.; Vitolo, S., High-temperature and low concentration CO2 sorption on Li4SiO4 based sorbents: Study of the used silica and doping method effects. Int. J. Greenh. Gas Con. 2011, 5, 741-748. (29). Zhang, Q.; Han, D.; Liu, Y.; Ye, Q.; Zhu, Z., Analysis of CO2 sorption/desorption kinetic behaviors and reaction mechanisms on Li4SiO4. Aiche J. 2012, 59, 901-911. (30). Yin, Z.; Wang, K.; Zhao, P.; Tang, X., Enhanced CO2 Chemisorption Properties of Li4SO4 , Using a 20


Page 20 of 43

Page 21 of 43 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

Water Hydrationl Calcination Technique. Ind. Eng. Chem. Res. 2016, 55. (31). Nakagaki, T., Enhanced Hydrogen Production Process from Coal Integrated with CO2 Separation Using Dual Chemical Looping. Energ. Procedia 2011, 4, 324-332. (32). Mejı ´a-Trejo, V. L.; Fregoso-Israel, E.; Pfeiffer, H., Textural, Structural, and CO2 Chemisorption Effects Produced on the Lithium Orthosilicate by Its Doping with Sodium (Li4-xNaxSiO4 ). Chem. Mater. 2008, 20, 7171-7176. (33). Shan, S. Y.; Li, S. M.; Jia, Q. M.; Jiang, L. H.; Wang, Y. M.; Peng, J. H., Impregnation precipitation preparation and kinetic analysis of Li4SiO4-based sorbents with fast CO2 adsorption rate. Ind. Eng. Chem. Res. 2013, 52, 6941-6945. (34). Rodrı ´guez-Mosqueda, R.; Pfeiffer, H., Thermokinetic analysis of the CO2 chemisorption on Li4SiO4 by using different gas flow rates and particle sizes. J. Phys. Chem. A 2010, 114, 4535-4541. (35). Nair, B. N.; Burwood, R. P.; Goh, V. J.; Nakagawa, K.; Yamaguchi, T., Lithium based ceramic materials and membranes for high temperature CO2 separation. Prog. Mater. Sci. 2009, 54, 511-541. (36). Pfeiffer, H.; Bosch, P.; Bulbulian, S., Synthesis of lithium silicates. J. Nucl. Mater. 1998, 257, 309-317. (37). Plaza, M. G.; González, A. S.; Pevida, C.; Rubiera, F., Green coffee based CO2 adsorbent with high performance in postcombustion conditions. Fuel 2015, 140, 633-648. (38). Sevilla, M.; Fuertes, A. B., Sustainable porous carbons with a superior performance for CO2 capture. Energ. Environ. Sci. 2011, 4, 1765-1771. (39). Hemalatha, P.; Bhagiyalakshmi, M.; Ganesh, M.; Palanichamy, M.; Murugesan, V.; Jang, H. T., Role of ceria in CO2 adsorption on NaZSM-5 synthesized using rice husk ash. J. Ind. Eng. Chem. 2012, 18, 260-265. (40). Witoon, T., Characterization of calcium oxide derived from waste eggshell and its application as CO2 sorbent. . Ceram. Int. 2011, 37, 3291-3298. (41). Zhang, Y.; Zhou, T.; Louis, B.; Yu, F.; Dan, J.; Wang, Q., Environmental benign synthesis of lithium silicates

and Mg-Al layered double hydroxide from

vermiculite mineral for CO2 capture Catalysts

2017, 7, 1-17. (42). Wang, K.; Guo, X.; Zhao, P.; Wang, F.; Zheng, C., High temperature capture of CO2

on

lithium-based sorbents from rice husk ash. J. Hazard. Mater. 2011, 189, 301-307. (43). W.;, L.; Wang, S.; Zhang, L.; Ni, Z., Water pollution characteristics of Dianchi Lake and the course of protection and pollution management. Environ. Earth Sci. 2015, 74, 3767-3780. (44). Duan, Y.; Pfeiffer, H.; Li, B.; Romero-Ibarra, I. C.; Sorescu, D. C.; Luebke, D. R.; Halley, J. W., CO2 capture properties of lithium silicates with different ratios of Li2O/SiO2 : an ab initio thermodynamic and experimental approach. Phys. Chem. Chem. Phys. 2013, 15, 13538-13558. (45). Shan, S. Y.; Jia, Q. M.; Jiang, L. H.; Li, Q. C.; Wang, Y. M.; Peng, J. H., Novel Li4SiO4 -based sorbents from diatomite for high temperature CO2 capture. Ceram. Int. 2013, 39, 5437-5441. (46). Durán-Muñoz, F.; Romero-Ibarra, I. C.; Pfeiffer, H., Analysis of the CO2 chemisorption reaction mechanism in lithium oxosilicate (Li8SiO6): a new option for high-temperature CO2 capture. J. Mater. Chem. A 2013, 1, 3919-3925. (47). Dalton, J. L.; Gardner, K. H.; Seager, T. P.; Weimer, M. L.; Spear, J. C. M.; Magee, B. J., Properties of Portland cement made from contaminated sediments. Resour. Conserv. Recy. 2003, 41, 227-241. (48). Chen, H. X.; Ma, X.; Dai, H. J., Reuse of water purification sludge as raw material in cement production. Cement Concerte Comp. 2010, 32, 436-439. (49). Pan, P.; Huang, P.; Wu, M.; Wang, Z.; Wang, P.; Jiao, X.; Xing, B., Physicochemical and sorption 21


Energy & Fuels 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

properties of thermally-treated sediments with high organic matter content. Bioresource Technol. 2012, 103, 367-373. (50). Pan, Y.; Zhang, Y.; Zhou, t.; Louis, b.; O'Hare, D.; Wang, Q., Fabrication of Lithium silicates as highly efficient high-temperature CO2 sorbents from SBA-15 precursor. Inorg. Chem. 2017, 56, 7821-7834. (51). Izquierdo, M. T.; Turan, A.; Garc´ıa, S.; Maroto-Valer, M., M., Optimization of Li4SiO4 synthesis conditions by a solid state method for maximum CO2 capture at high temperature. J. Mater, Chem. A. 2018, 6, 3249-3257. (52). Venegas, M. J.; Fregoso-Israel, E.; Escamilla, R.; Pfeiffer, H., Kinetic and reaction mechanism of CO2 sorption on Li 4SiO4 : study of the particle size effect. Ind. Eng. Chem. Res. 2007, 46, 2407-2412. (53). Wang, K.; Yin, Z.; Zhao, P., Synthesis of macroporous Li4SiO4 via a citric acid-based sol-gel route coupled with carbon coating and its CO2 chemisorption properties. Ceram. Int. 2016, 42, 2990-2999. (54). Nambo, A.; He, J.; Nguyen, T. Q.; Atla, V.; Druffel, T.; Sunkara, M., Ultrafast carbon dioxide sorption kinetics using lithium silicate nanowires. nano lett. 2017, 17. (55). Wang, k.; Zhao, p.; Guo, X.; Li, Y.; Han, D.; Chao, Y., Enhancement of reactivity in Li4SiO4-based sorbents from the nano-sized rice husk ash for high-temperature CO2 capture. Energ. Convers. Manage. 2014, 81, 447-454. (56). Zhang, Y.; Yu, P.; Louis, B.; Wang, Q., Scalable synthesis of the lithium silicate-based high-temperature CO2 sorbent from inexpensive raw material vermiculite. Chem. Eng. J. 2018, 349, 562-573. (57). Zubbri, N. A.; Mohamed, A. R.; Mohammadi, M., Parametric study and effect of calcination and carbonation conditions on the CO2 capture performance of lithium orthosilicate sorbent. Chinese J. Chem. Eng. 2018, 26, 631-641. (58). Zhang, Q.; Zang, S.; Ye, Q.; Wu, Y.; Ni, Y., Behaviors and kinetic models analysis of Li4SiO4 under various CO2 partial pressures Aiche J. 2016, 63. (59). Zhang, Z.; Zhang, Q.; Wang, H.; Ni, Y.; Zhu, Z., Absorption behaviors study on doped Li4SiO4 under a humidified atmosphere with low CO2 concentration Int. J. Hydrogen Energ. 2014, 39, 17913-17920. (60). Chen, X.; Xiong, Z.; Qin, Y.; Gong, B.; Tian, C.; Zhao, Y.; Zhang, J.; Zheng, C., High-temperature CO2 sorption by Ca-doped Li4SiO4 sorbents. Int. J. Hydrogen Energ. 2016, 41, 13077-13085. (61). Seggiani, M.; Puccini, M.; Vitolo, S., Alkali promoted lithium orthosilicate for CO2 capture at high temperature and low concentration. Int. J. Greenh. Gas Con. 2013, 17, 25-31. (62). Zhou, Z.; Wang, K.; Yin, Z.; Zhao, P.; Su, Z.; Sun, J., Molten K2CO3-promoted high-performance Li4SiO4 sorbents at low CO2 concentrations. Thermochim Acta 2017, 655, 284-291. (63). Wang, K.; Yin, Z.; Zhao, P.; Zhou, Z.; Su, Z.; Sun, J., Development of metallic element-stabilized Li4SiO4 sorbents for cyclic CO2 capture. Int. J. Hydrogen Energ. 2017, 42, 4224-4232.

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Figure 1. The flow charts for synthesis Li4SiO4 from sediment. (a) The sediment is treated with acid to obtained SiO2 sample. (b) Synthesis of Li4SiO4 from the SiO2 sample obtained in step (a).

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Table 1. The sediment of Dianchi Lake XRF chemical composition analyses Element

SiO2

Al2O3

CaO

TiO2

K2O

MgO

SO3

P2O5

Na2O

MnO

Fe2O3

Content(%)

42.09

20.10

7.28

3.38

1.97

1.70

0.66

0.30

0.16

0.12

13.05

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Table 2. The SiO2 quantities when the sediment was treated with different volume ratio of leaching acid. 6M

6M

6M

6M

Acid HCl:HNO3 SiO2(g g-1)

0.63

2HCl:HNO3 0.72

3HCl:HNO3 0.74

25


4HCl:HNO3 0.77

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Figure 2. XRD analyze of (a) raw sediment sample.

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Figure 3. XRD analysis of the SiO2 sample obtained from leaching treatment with (a) CN-1, (b) CN-2, (c) CN-3, (d) CN-4, for 24 h at 80 oC.

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Figure 4. CO2 sorption capacity of Li4SiO4-x-4 (x=1, 2, 3, 4) samples synthesized at 750 oC for 6 h, and CO2 sorption capacity was evaluated at 650 oC.

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Figure 5. CO2 sorption capacity of Li4SiO4-x-5 (x=1, 2, 3, 4) samples synthesized at 750 oC for 6 h, and CO2 sorption capacity was evaluated at 650 oC.

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Figure 6. CO2 sorption capacity of Li4SiO4-t (t=3, 4, 5, 8, 10) samples with 6M CN-2 treated, and CO2 sorption capacity was evaluated at 650 oC.

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Figure 7. XRD patterns of Li4SiO4-2-t (t = 3, 4, 5, 8, 10) samples.

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Table 3. BET surface area, BJH pore volume and BJH pore size of Li4SiO4-2-t (t = 3, 4, 5, 8, 10) samples.

BET surface area (m2/g) Pore volume (cm3/g) Pore size (Å)

Li:Si = 3

Li:Si = 4

Li:Si = 5

Li:Si = 8

Li:Si = 10

4.0926

14.3461

4.3705

4.1679

2.7398

0.033043

0.058534

0.044366

0.042202

0.131913

96.941

87.846

93.797

93.213

92.561

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Figure 8. BET analysis of synthesized Li4SiO4-2-4 sample.

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Figure 9. The CO2 sorption performance of Li4SiO4-2-4 samples synthesized at different temperature (650, 700, 750 and 800 oC, and CO2 sorption capacity was evaluated at 650 oC )

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Figure 10. The CO2 sorption performance of Li4SiO4-2-4 samples synthesized at 750 oC

for different time, and CO2 sorption capacity was evaluated at 650 oC.

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Figure 11. Isotherms of Li4SiO4-2-4 sorbents evaluated at different sorption

temperatures of 600, 650, 700 and 750 oC.

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Energy & Fuels

Table 4. Kinetic parameters of Li4SiO4-2-4 sample Name

T(oC)

K1(s-1)

K2(s-1)

R

Li4SiO4-2-4 sample

600 650 700 750

3.81×10-3 4.68×10-3 6.21×10-3 7.81×10-3

3.19×10-4 5.96×10-4 6.21×10-3 7.84×10-5

0.999 0.998 0.954 0.944

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Energy & Fuels 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

Figure 12. CO2 sorption/desorption cycling performance of (a) Li4SiO4-2-4 sample (sorption at 650 oC, desorption at 750 oC), (b) Li4SiO4-P sample (sorption at 650 oC, desorption at 750 oC), (c) Li4SiO4-2-4 sample (sorption and desorption at 650 oC), (d) Li4SiO4-P sample (sorption and desorption at 650 oC), (e) Li4SiO4-2-4 sample (sorption and desorption at 700 oC), (f) Li4SiO4-P sample (sorption and desorption at 700 oC).

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Energy & Fuels

Table 5. Summary of Li4SiO4 materials and their CO2 capture cycle performance. Material

Adsorption Conditions

Desorption Conditions

Cycles

Performance From 1th about 33 wt% to 2th about 25 wt%, then gradually reduce Stable at around 28 wt%

Published year

Ref.

2017

54

2014

55

Li4SiO4 nanowires

700 oC, 10 min, Pure CO2

720 oC, 10 min, Pure N2

4

Li4SiO4 Nano-sized Li4SiO4, Vermiculite as silicon source Li4SiO4, Vermiculite as silicon source



15



20

Stable at around 17 wt%

2018

56



20

Form 1th 29.37 wt% to 20th 15 wt%

2017

41

Li4SiO4



27.6 18.7

2018

56

Li4SiO4


800 oC, Pure N2

10

35.2 26.5

2018

57

800 oC, Pure N2

10

2016

58

2014

59

2016

60

2016

19

2016

30

Li4SiO4

Li4SiO4

700 oC, 160 min, Pure CO2 575 oC, 200 min, Pure CO2

20

700 oC, Pure N2

10

Li4SiO4



15

Li4SiO4



48

Li4SiO4 Solid-state method



15

From 1th wt% to 20th wt% From 1th wt% to 10th wt%

From 1th 25 wt% to 10th 23 wt% From 2th 24.4 wt% to 10th 22.2 wt% From 1th 32.5 wt% to 15th 13.1 wt% From 1th 33 wt% to 48th 27 wt% From 1th ~11.5 wt% to 15th ~10 wt%

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Energy & Fuels 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

Li4SiO4 Wet-mixing method Li4SiO4+30 wt% k2CO3 Li4SiO4+0.1 k2CO3



580 oC, 60 min, 4vol. CO2 575 oC, 30 min, 15vol. CO2

700 oC, 15 min, Pure N2 700 oC, 10 min, Pure N2

580 oC, 60 min, 4vol. CO2


650 oC, 60 min, Pure CO2 650 oC, 60 min, Pure CO2

650 oC, 60 min, Pure N2 750 oC, 60 min, Pure He

Ce2- Li4SiO4



10

Li4SiO4+6 mol% Ca



15

Li4SiO4+32 mol% Ca Li4SiO4, Diatomite as silicon source



15

700 oC, 30 min, 50 vol. CO2


16

Li4SiO4+30 wt% Na2CO3 Li3.7Fe0.1SiO4 Li3.7Fe0.1SiO4

15

25 10

25

5 5

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From 1th ~28 wt% to 15th ~26 wt% Stable at around 19 wt% Stable at around 30 wt% From 1th 18.5 w% to 25th 6.74 wt% From 1th 22 w% to 5th 18.7 wt% From 1th 23 w% to 5th 14 wt% From 1th 32.5 w% to 6th 29 wt%, then gradually increase. From 1th 31.2 w% to 15th 26 wt% From 1th 25 w% to 15th 20 wt% From 1th 34.14 w% to 10th 27.7 wt%

40


2016

30

2013

61

2017

62

2013

61

2006

22

2006

22

2017

63

2016

60

2016

60

2013

45

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Energy & Fuels

Figure 13. SEM image of (a) Li4SiO4-2-4 sample, (b) Li4SiO4-2-4 sample after 1 cycles at 700 oC, (c) Li4SiO4-2-4 sample after 6 cycles at 700 oC, (d) Li4SiO4-2-4 sample after 12 cycles at 700 oC, (e) Li4SiO4-2-4 sample after 22 cycles at 700 oC, (f) Li4SiO4-P sample, (g) Li4SiO4-P sample after 1 cycles at 700 oC, (h) Li4SiO4-P sample after 6 cycles at 700 oC, (i) Li4SiO4-P sample after 12 cycles at 700 oC, (j) Li4SiO4-P sample after 22 cycles at 700 oC.

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Figure 14. (a) One CO2 sorption/desorption cycle of (a) Li4SiO4-2-4 sample (sorption at 650 oC, desorption at 750 oC), (b) Li4SiO4-P sample (sorption at 650 oC, desorption at 750 oC), (c) Li4SiO4-2-4 sample (sorption and desorption at 650 oC), (d) Li4SiO4-P sample (sorption and desorption at 650 oC), (e) Li4SiO4-2-4 sample (sorption and desorption at 700 oC), (f) Li4SiO4-P sample (sorption and desorption at 700 oC).

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Energy & Fuels

Graphical abstract

43


Unexpected highly reversible lithium silicates based CO2 sorbents

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