共查询到20条相似文献,搜索用时 15 毫秒
1.
Qi Zhang Dong Peng Sai Zhang Qian Ye Yongqiang Wu Yanhui Ni 《American Institute of Chemical Engineers》2017,63(6):2153-2164
The absorption behaviors of Li4SiO4 sorbent under various CO2 partial pressures and temperatures were investigated through numerical and experimental methods. It was found that Li4SiO4 showed poor absorption capacity at high temperatures (>525°C) under CO2 partial pressure of 5066 Pa. This phenomenon was explained by the thermodynamic results from FactSage5.5 software. Meanwhile, a modified Jander‐Zhang model based on the double‐shell structure of the Li4SiO4 sorbent was developed to describe the absorption kinetic behaviors of CO2 on Li4SiO4. The results showed that the modified Jander‐Zhang model could fit the kinetic experimental data well. Furthermore, the influence of steam on CO2 absorption was also analyzed by the modified Jander‐Zhang model. The results showed that the activation energy in the absorption process with steam was smaller than that without steam, which indicated that the presence of steam could promote the CO2 diffusion in product layer, therefore, improving the sorption capacity. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2153–2164, 2017 相似文献
2.
Li4SiO4 is a promising sorbent for high temperature CO2 capture. It could be synthesized from three different Li sources (LiNO3, LiOH, and Li2CO3) by using the solid state reaction method. The effects of Li sources on the structure and CO2 adsorption/desorption properties of Li4SiO4 sorbents were analyzed in this work. The results showed that Li4SiO4 sorbents could be synthesized at a lower temperature by using LiNO3 and LiOH as the starting materials, which could reduce the sintering during the synthesis process and increase the surface area of synthesized Li4SiO4. During the CO2 adsorption/desorption cycles, Li4SiO4 sorbents derived from LiNO3 and LiOH presented higher initial CO2 adsorption capacities than those from Li2CO3. After 15 cycles, the adsorption efficiency of Li4SiO4 derived from LiNO3 showed no or slight decrease, while that from LiOH rapidly decreased to 20% of the initial value. This was because Li4SiO4 derived from LiNO3 had high surface area and porosity before CO2 adsorption/desorption cycles, and its surface area even increased after cycles. However, the surface area of Li4SiO4 derived from LiOH decreased greatly due to serious sintering. For Li4SiO4 derived from Li2CO3, its morphology and surface area were almost unchanged before and after CO2 adsorption/desorption cycles. 相似文献
3.
《Ceramics International》2022,48(22):33048-33057
Alkali silicate-based ceramics sorbents were regarded as particularly suitable materials for CO2 capture at high temperatures, however, the CO2 capture behaviors of Na4SiO4 had been seldom investigated. In this work, the Na4SiO4 ceramics samples were prepared using the one-step synthesized method, and the CO2 sorption/desorption performances at high temperatures, the thermal stability, and the cycling stability of Na4SiO4 were systematically investigated. It was demonstrated that the maximum CO2 sorption capacity of SO-3 sample reached 19.4 wt% at 725 °C, and the optimal condition of cycling tests were 750 °C for sorption and 800 °C for desorption based on the sorption/desorption capacity and rate, which exhibited good thermal stability and high cyclic stability. Besides, the kinetic analysis results showed that the diffusion process was the rate-determining step of CO2 adsorption, which was more dependent on temperature than the chemisorption process. The structure and surface morphology variations were also investigated, it was interesting that there was a special “fish scale” surface structure after the sorption process, revealing that the melting phenomenon happened during the chemisorption reaction process. By comparing with common sorbent Li4SiO4, the material and CO2 capture costs of Na4SiO4 were much lower. These results proved that Na4SiO4 was expected to be a suitable high temperature CO2 capture material as a good supplement to alkali silicate-based ceramics sorbents. 相似文献
4.
Yingchao Hu Wenqiang Liu Yuandong Yang Xianliang Tong Qianjun Chen Zijian Zhou 《Ceramics International》2018,44(14):16668-16677
Li4SiO4 sorbents for high-temperature CO2 removal have drawn extensive attention owing to their potential application in carbon capture and storage (CCS). The major challenge in the application lies in the poor CO2 capture performance under realistic conditions of low CO2 concentrations, owing to the dense structure and poor porosity. In this work, Li4SiO4 sorbents were prepared with porous micromorphologies and large contact areas using a variety of organometallic Li-precursors, achieving fast CO2 sorption kinetics, high capacity and excellent cyclic stability at a low CO2 concentration (15?vol%). It was found that a high conversion of ~?74% was maintained for pure Li4SiO4 even after 100 sorption/desorption cycles. Moreover, by doping with Na2CO3 to reduce the CO2 diffusion resistance, the conversion of the sorbent was further enhanced to 93.2%. The enhancement mechanism of alkali carbonate have been proven here to be ascribed to the formation of the eutectic melt of Li/Na carbonates, the existence and function of which has been confirmed in this study. 相似文献
5.
Synthesis,kinetic study,and reaction mechanism of Li4SiO4 with CO2 in a slurry bubble column reactor
AbstractThis study was performed to investigate the synthesis, kinetic and reaction mechanism of Li4SiO4 with CO2 in a slurry bubble column reactor. The Li4SiO4 powder sample was prepared via a solid-state reaction. The sample was characterized via X-ray diffraction (XRD) analysis and verified as a single phase. The median diameter of the sample was measured using the laser diffraction and scattering method as about 20?μm. The synthesized sample was suspended in binary molten carbonate of Li2CO3–K2CO3 having a molar ratio of 38:62. The experimental results show that Li4SiO4 in the slurry bubble column absorbed approximately a stoichiometric amount of CO2. The kinetic study shows that the CO2 reaction behavior on the Li4SiO4 surface was fitted to a double exponential model and the limiting step of the reaction was lithium diffusion. The mass transfer coefficient of CO2 and rate constant of reaction with Li4SiO4 were studied to understand the overall absorption mechanism in the reactor. The resistance for the direct reaction of CO2 on the Li4SiO4 was much smaller than the resistance for the mass transfer of CO2 to the Li4SiO4. We can conclude that the direct contact of CO2 with Li4SiO4 was the main path for the reaction. 相似文献
6.
ShaoYun Shan QingMing Jia LiHong Jiang QinChao Li YaMing Wang JinHui Peng 《Ceramics International》2013,39(5):5437-5441
Using inexpensive porous diatomite as silicon source, novel Li4SiO4-based sorbents for high temperature CO2 capture were prepared through the solid-state reaction method at lower temperature (700 °C). Effect of different raw material ratios on CO2 absorption capacity was investigated. The results showed that CO2 absorption capacity was dependent on the raw material ratio. When the raw material ratio was 2.6:1, the CO2 absorption capacity reached 30.32 wt% (83% of the theoretical absorption capacity) in the atmosphere (50 mL/min N2 and 50 mL/min CO2). Meanwhile, it was found that the as-prepared Li4SiO4-based sorbents from diatomite exhibited good absorption–desorption performance. 相似文献
7.
Guangfan Tan Xin Hu Liang Cai Haifeng Xue Xiuhong Yang Yingchun Zhang 《Journal of the American Ceramic Society》2023,106(7):4304-4320
The bi-phase Li2TiO3–Li4SiO4 ceramic pebbles have been considered a promising breeder to realize the tritium self-sustainment in the blanket. However, up to now, the reported ceramic pebbles have the disadvantages of low yield, poor crushing load, and loose internal structure, which cannot meet the practical application requirements. In this work, the Li2TiO3–Li4SiO4 ceramic pebbles with excellent mechanical properties were fabricated successfully via the centrifugal granulation method with the assistance of introducing a spray-drying process, simulating particle trajectory by discrete element software and improving bonding interface between core and shell with ethylene glycol. The composition, microstructure, and inner structure of the Li2TiO3–Li4SiO4 ceramic pebbles were investigated, respectively, through X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray computed tomography (CT). It can be found that the employment of the ethylene glycol solution on the surface of Li2TiO3 can make the core and the shell combine well. Moreover, the effect of the rolling speed of the Li2TiO3–Li4SiO4 ceramic pebbles was investigated via discrete element method (EDEM) simulation and experiments. The experimental results displayed that the Li2TiO3–Li4SiO4 ceramic pebbles sintered at 1100°C for 2 h have a uniform diameter of 1 mm, a good sphericity of 0.97, and an excellent crushing load of 82.4 N, which are superior to those pebbles that obtained by using the traditional wet methods. Moreover, the CT results showed that the appropriate porosity of the core was 3.21% and of the shell was 10.73%. Therefore, the simple centrifugal granulation method can be applied to prepare the Li2TiO3–Li4SiO4 ceramic pebbles in a large scale and shed a light to investigate the relevant advanced biphasic tritium breeder materials in the future. 相似文献
8.
Rentian Xiong 《Chemical engineering science》2003,58(19):4377-4385
Potassium-doped lithium zirconate (Li2ZrO3) sorbents with similar crystallite but different aggregate sizes were prepared by a solid-state reaction method from mixtures of Li2CO3, K2CO3, and ZrO2 of different particle sizes. Carbon dioxide sorption rate on the prepared Li2ZrO3 sorbents increases with decreasing sorbent aggregate size. It is the size of the aggregate, not the crystallite, of Li2ZrO3 that controls the sorption rate. Temperature effect on CO2 sorption is complex, depending on both kinetic and thermodynamic factors. A mathematical model based on the double-shell sorption mechanism was established for CO2 sorption kinetics and it can fit experimental data quite well. Above 500°C, the rate-limiting step of CO2 sorption is the diffusion of oxygen ions through the ZrO2 shell formed during the carbonation reaction. Oxygen ion conductivities in the ZrO2 shell were obtained by regression of the experimental CO2 uptake curves with the model and are consistent with the literature data. 相似文献
9.
High‐Temperature Capture of CO2 on Lithium‐Based Sorbents Prepared by a Water‐Based Sol‐Gel Technique
下载免费PDF全文
![点击此处可从《化学工程与技术》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A convenient water‐based sol‐gel technique was used to prepare a highly efficient lithium orthosilicate‐based sorbent (Li4SiO4‐G) for CO2 capture at high temperature. The Li4SiO4‐G sorbent was systematically studied and compared with the Li4SiO4‐S sorbent prepared by solid‐state reaction. Both sorbents were characterized by X‐ray diffraction, scanning electron microscopy, nitrogen adsorption, and thermogravimetry. The CO2 sorption stability was investigated in a dual fixed‐bed reactor. Li4SiO4‐G exhibited a special Li4SiO4 structure with smaller crystalline nanoparticles, larger surface area, and higher CO2 adsorption properties as compared with Li4SiO4‐S. The Li4SiO4‐G sorbent also maintained higher capacities during multiple cycles. 相似文献
10.
《Ceramics International》2023,49(16):26778-26785
The neutron multiplier lead (Pb) containing Li2TiO3-0.5Li4SiO4–Pb was prepared, which aimed at the improvement of the tritium release performance of the lithium ceramic without an increase in lithium density. Li2TiO3-0.5Li4SiO4–Pb and that without Pb were irradiated at Kyoto University Research Reactor (KUR) with the thermal neutron flux of 5.5 × 1012 n s−1 cm−2 and the fast neutron flux of 1.2 × 1012 n s−1 cm−2. Fast neutrons can trigger the Pb (n, 2n) reaction. The tritium release experiments were conducted using the tritium thermal desorption spectroscopy (tritium-TDS) system. Compared with Li2TiO3-0.5Li4SiO4, the tritium release rate at the lower temperature range was higher than that for Li2TiO3-0.5Li4SiO4–Pb. The tritium-TDS spectrum was also shifted to the lower temperature side. The isothermal heating experimental results confirmed that tritium in the form of gas species (HT) was controlled by the diffusion process, while the trapping and de-trapping process contributed to the total tritium release. Further, 3 keV D2+ implantation with the fluence of 2.0 × 1022 D m−2 and subsequent TDS measurements were performed. It was shown that the D2 release at the lower temperature side was increased for Li2TiO3-0.5Li4SiO4–Pb. Meanwhile, HD and HDO release at higher temperature side was significantly decreased. 相似文献
11.
Ruichong Chen Akito Ipponsugi Ran Oyama Jianqi Qi Haomin Wang Zhangyi Huang Hao Guo Tiecheng Lu Wei Feng Kazunari Katayama 《International Journal of Applied Ceramic Technology》2023,20(4):2576-2585
The long-term thermal stability of tritium breeding materials during service is a key factor to ensure efficient tritium release. In this study, the long-term thermal stability of advanced Li4TiO4–Li2TiO3 core–shell breeding pebbles under continuous heating in 1%H2/Ar at 900°C was investigated for the first time. The results show that this core–shell material loses 3.4% Li mass after heating for 30 days, resulting in a reduction in Li density to .415 g/cm3, which is still significantly higher than other breeding materials. The moisture in the sample bed will determine the form of Li volatilization and thus affect the rate of Li mass loss. The core–shell pebbles maintain favorable phase stability during long-term heating, and the grain sizes of the Li2TO3 shell and Li4TiO4 core after 30 days of heating are 6.5 ± 1.5 and 6.9 ± 2.5 μm, respectively. Moreover, the samples did not crack or collapse during long-term heating and still had a satisfactory crushing strength of 37.61 ± 7.13 N after 30 days of heating. Overall, the high Li density and good thermal stability during long-term heating demonstrate that the Li4TiO4–Li2TiO3 core–shell breeding pebbles are a very reliable tritium breeding material for long-term service under harsh operating conditions. 相似文献
12.
《Ceramics International》2017,43(2):2314-2319
Li4SiO4 pebbles and Li2O pebbles have been considered as the potential candidates for tritium breeders. Li2O exhibits higher lithium density whereas worse lithium loss and hygroscopicity compared with Li4SiO4. It is anticipated to obtain an advanced breeder by combining Li4SiO4 with Li2O. The coexistence of Li4SiO4 and Li2O powders could not be obtained by solid state reaction using Li2CO3 as lithium source, while the biphasic Li4SiO4-xLi2O (x=0.1, 0.2, 0.3, 0.4) powders were prepared by sol-gel method in this experiment. Meanwhile, the biphasic Li4SiO4-xLi2O pebbles were fabricated by a wet method for the first time. The Li2O aggregated at the grain boundaries and promoted the grain growth of the Li4SiO4. The grain size and the crush load of the Li4SiO4-0.3Li2O pebbles reached 32.3 µm and 46.5 N, respectively. 相似文献
13.
The Li content and anion lattice of Li4SiO4 were modified to improve ionic conductivity. Li2CO3 and Si3N4 were mixed in a ratio of Li/Si?=?4.5 and heated in NH3 at 820?°C, which resulted in the formation of the oxynitride, Li4.1SiO3.9N0.1. Powder X-ray diffraction analyses revealed Li4.1SiO3.9N0.1 and Li4SiO4 to be isostructural with a subtle variation in the lattice constants. Diffuse-reflectance absorption spectroscopy, however, showed a significant decrease in the band gap, from 5.6?eV in Li4SiO4 to 4.8?eV in Li4.1SiO3.9N0.1. X-ray photoelectron spectra of the Li 1s and Si 2p levels revealed enhanced lattice covalency in Li4.1SiO3.9N0.1 compared to the oxide phase. The ionic conductivity of Li4SiO4 and Li4.1SiO3.9N0.1 were measured by ac impedance spectroscopy over the temperature range 100–400?°C. Non-linear fitting analysis of the equivalent circuit revealed that the ionic conductivity of Li4.1SiO3.9N0.1 was approximately one order of magnitude higher than that of Li4SiO4. 相似文献
14.
Development of lithium disilicate-based glass-ceramics critically depends on use of nucleating agent in the glass matrix. The present study reports the effect of externally added nucleating agent Li3PO4 in Li2O–K2O–MgO–ZnO–ZrO2–Al2O3–SiO2 system which is compared with a reference composition (GC1) (SiO2:Li2O = 2.16:1) prepared with in situ formed Li3PO4. For externally added Li3PO4, two compositions were studied. In one case (GC2) before addition of Li3PO4, SiO2:Li2O ratio in glass was maintained as 2.87:1 and in another case (GC3) SiO2:Li2O ratio in glass was maintained same as reference GC1 that is, 2.16:1. The glasses were characterized by using MAS-NMR spectroscopy. Sintering and crystallization behavior of the glass-ceramics was characterized by using XRD, SEM, DTA. Due to in situ formation of Li3PO4, GC1 resulted in a dense sample with finer crystals of lithium disilicate. In GC2 and GC3, externally added lithium phosphate, which was in the form of ultrafine aggregated particles, formed flower-like colonies of radially outward crystals. Higher SiO2:Li2O ratio in GC2 resulted in lithium disilicate crystals and high viscous glass causing large air entrapment and so less densification. GC3 with higher lithia in glass showed higher densification than GC2 but only lithium metasilicate crystals were formed. 相似文献
15.
《Ceramics International》2021,47(20):28744-28753
The bagasse, which is a typical agricultural and forestry waste, was employed as the silicon source to produce Li4SiO4-based ceramics with superior CO2 sorption performance. It is found that the presence of impurities elements in the bagasse ash will bring complex side reactions and form side products during the sorbent preparation process, which are extremely harmful to the performance of the synthetic sorbent. Pretreatment has been considered as an effective approach to reduce the impurities elements. In this work, the effects and mechanisms of water/acid washing pretreatments on bagasse ash were firstly detailed investigate and compared. The results indicate that the hydrochloric acid washing pretreatment can effectively remove the residual metals (Ca, Fe, etc.) in the sample in addition to the water-soluble impurities (K, P, S, etc.). The maximum sorption capacity of sorbent synthesized by the acid washing pretreatment is about 0.32 g/g sorbent and the superior performance can be well maintained over 10 cycles. A novel technical route utilizing the ash from biomass power plants for in-situ CO2 capture has been developed, which has great potential for carbon capture in the future. 相似文献
16.
A kinetic study of ethanol steam reforming to produce hydrogen within the region of kinetic rate control was carried out. A Ni(II)–Al(III) lamellar double hydroxide as catalyst precursor was used. H2, CO, CO2 and CH4 were obtained as products. Using the Langmuir–Hinshelwood (L–H) approach, two kinetic models were proposed. The first was a general model including four reactions, two of them corresponding to ethanol steam reforming and the other two to methane steam reforming. When high temperatures and/or high water/ethanol feed ratios were used, the system could be reduced to two irreversible ethanol steam reforming reactions. 相似文献
17.
Coupled experimental phase diagram study and thermodynamic optimization of the Li2O–MgO–SiO2 system
下载免费PDF全文
![点击此处可从《Journal of the American Ceramic Society》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Bikram Konar Dong‐Geun Kim In‐Ho Jung 《Journal of the American Ceramic Society》2018,101(4):1711-1726
A coupled key phase diagram study and critical evaluation and optimization of all available experimental data of the Li2O–MgO–SiO2 system was performed to obtain a set of Gibbs energy functions to reproduce all the reliable phase equilibria and thermodynamic data. Differential scanning calorimetry measurements and equilibration/quenching experiments were performed in the Li2SiO3–MgO and Li4SiO4–Mg2SiO4 sections, respectively, using sealed Pt capsules to prevent the volatile loss of Li. According to the present experimental results, Li2MgSiO4 is the only compound present in the Li4SiO4–Mg2SiO4 isopleth, which shows a peritectic melting at 1465 ± 6°C (1738 ± 6 K). The Modified Quasichemical Model, which considers short‐range ordering in the melt, was employed to describe the thermodynamic properties of the liquid phase. The Li4SiO4–Li2MgSiO4 and Mg2SiO4‐rich solid solutions were modeled using the Compound Energy Formalism. 相似文献
18.
CO2 sorption capacities of the neat and silica‐supported 1‐butyl‐3‐methylimidazolium‐based ionic liquids (ILs) were measured under atmospheric pressure. The silica‐supported ILs were synthesized by the impregnation‐vaporization method and charactrized by N2 adsorption/desorption and thermogravimeteric analysis (TGA). Evaluation of the effects of influential factors on sorption capacity demonstrated that by increase of the temperature, flow rate, and the weight percentage of ILs in sorbents, the sorption capacity decreases. Among the sorbents, [Bmim][TfO] and SiO2‐[Bmim][BF4](50) had the highest capacity. By increasing the IL portion in SiO2‐[Bmim][BF4], the selectivity for CO2 to CH4 could be improved. The CO2‐rich sorbents could be easily recycled. 相似文献
19.
Coupled reaction and solvent extraction process to form Li2CO3: Mechanism and product characterization
下载免费PDF全文
![点击此处可从《American Institute of Chemical Engineers》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Zhiyong Zhou Fan Liang Wei Qin Weiyang Fei 《American Institute of Chemical Engineers》2014,60(1):282-288
A coupled reaction and solvent extraction process to produce Li2CO3 from LiCl and CO2 is proposed. The aqueous reaction occurs with difficulty and is not spontaneous at 298 K. To ensure the continuous reaction between LiCl and CO2 to produce Li2CO3, it is necessary to remove HCl. Experiments conducted in an open reactor at room‐temperature showed that the product sample was pure Li2CO3 with a particle‐size distribution in two regions and a larger number of small crystals. The large and small crystals were obtained by radial growth in the free aqueous phase and in water‐in‐oil structures with growth space constraints, respectively. Factors influencing the particle‐size distribution and Li2CO3 morphology were investigated. A short reaction time, large phase ratio (O/A), low–temperature, and surfactant addition (TritonX‐100) can increase the number of small particle crystals and reduce the number and volume of large particle crystals. © 2013 American Institute of Chemical Engineers AIChE J, 60: 282–288, 2014 相似文献
20.
Mohammed J. Al-Marri Yussuf O. Kuti Majeda Khraisheh Anand Kumar Mahmoud M. Khader 《化学工程与技术》2017,40(10):1802-1809
The kinetics of adsorption of CO2 on solid sorbents based on polyethyleneimine/mesoporous silica (PEI/MPS) was studied by following the mass gain during CO2 flow. Linear (PEI‐423) and branched (PEI‐10k) polymers were studied. The solid sorbents were synthesized by impregnating the PEI into MPS foam. The kinetics of adsorption was fitted with a double‐exponential model. In contrast, the desorption process obeyed first‐order kinetics. The activation energy of desorption of PEI‐423 was lower than that of PEI‐10k, presumably because the branched polymer required more energy to expose its nitrogen to CO2. To increase the CO2 sorption capacity, the MPS was treated with nonionic surfactant materials prior to impregnation with PEI. This also lowered the maximum sorption temperature and desorption activation energies. 相似文献