| 1. |
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| 2. |
- Fan, Tengteng, et al.
(författare)
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CO2/N2 separation using supported ionic liquid membranes with green and cost-effective [Choline][Pro]/PEG200 mixtures
- 2016
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Ingår i: Chinese Journal of Chemical Engineering. - : Elsevier BV. - 1004-9541 .- 2210-321X. ; 24:11, s. 1513-1521
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Tidskriftsartikel (refereegranskat)abstract
- The high price and toxicity of ionic liquids (ILs) have limited the design and application of supported ionic liquid membranes (SILMs) for CO2 separation in both academic and industrial fields. In this work, [Choline][Pro]/polyethylene glycol 200 (PEG200) mixtures were selected to prepare novel SILMs because of their green and cost-effective characterization, and the CO2/N2 separation with the prepared SILMs was investigated experimentally at temperatures from 308.15 to 343.15 K. The temperature effect on the permeability, solubility and diffusivity of CO2 was modeled with the Arrhenius equation. A competitive performance of the prepared SILMs was observed with high CO2 permeability ranged in 343.3-1798.6 barrer and high CO2/N2 selectivity from 7.9 to 34.8. It was also found that the CO2 permeability increased 3 times by decreasing the viscosity of liquids from 370 to 38 mPa·s. In addition, the inherent mechanism behind the significant permeability enhancement was revealed based on the diffusion-reaction theory, i.e. with the addition of PEG200, the overall resistance was substantially decreased and the SILMs process was switched from diffusion-control to reaction-control.
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| 3. |
- Bao, Ningzhong, et al.
(författare)
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Thermodynamic modeling and experimental verification for ion-exchange synthesis of K2O·6TiO2 and TiO2 fibers from K2O·4TiO2
- 2002
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Ingår i: Fluid Phase Equilibria. - 0378-3812 .- 1879-0224. ; 193, s. 229-243
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Tidskriftsartikel (refereegranskat)abstract
- A thermodynamic model was established to determine ion-exchange conditions for the synthesis of potassium hexatitanate (K2O·6TiO2) and titanium dioxide (TiO2) from potassium tetratitanate (K2O·4TiO2) fiber. In the proposed model equilibrium species in the solid phase and corresponding ion-exchange equilibrium constants at 298.15 K were determined from the experimental data of Sasaki et al. [Inorg. Chem. 24 (1985) 2265]. In order to verify the proposed model, prediction results were compared with experimental data determined in literature and those measured in this work. The comparison shows a good agreement. Based on this, the proposed model was also used to predict more extensive suitable conditions for the synthesis of K2O·6TiO2 and TiO2.
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| 4. |
- Cao, Jian, et al.
(författare)
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Heterogeneous consecutive reaction kinetics of direct oxidation of H2 to H2O2: Effect and regulation of confined mass transfer
- 2023
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Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 455
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Tidskriftsartikel (refereegranskat)abstract
- Porous catalysts in heterogeneous reactions have played an important role in the modern chemical industry, but it is still challenging to quantitatively describe mass transfer and surface reaction behaviors of reactants in nano-confined space. Direct synthesis of hydrogen peroxide (H2O2) is considered as an attractive alternative to anthraquinone oxidation process, while the confined mass transfer of H2O2 in porous catalysts limits the reactivity. In this work, taking the consecutive reaction of H2O2 synthesis as an example, a quantitative method in modeling the effects of confined mass transfer on the reactivity was studied. More specifically, calorimetry was developed to characterize the confined structures of porous carbon experimentally, the linear nonequilibrium thermodynamics and the statistical mechanics method were further combined. Then, the heterogeneous consecutive reaction kinetics and the Thiele modulus influenced by confined mass transfer were modeled. Consequently, regulation strategies were proposed with the help of theoretical models. The optimized catalyst with biological skeleton carbon support and 0.5 wt% palladium loading shows an excellent catalytic performance. Lastly, for the mesoscience in heterogeneous reaction, the resistance was explored as a quantitative descriptor to compromise in the competition between mass transfer and surface reaction. The mesoscale structures were considered as the dynamic spatiotemporal distribution of substance concentrations, and the resistance minimization multi-scale (RMMS) model was proposed.
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| 5. |
- Chen, Yifeng, et al.
(författare)
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Developing aqueous porous carbons for biogas upgrading
- 2024
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Ingår i: Separation and Purification Technology. - : Elsevier B.V.. - 1383-5866 .- 1873-3794. ; 329
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Tidskriftsartikel (refereegranskat)abstract
- Developing novel sorbents is essential for biogas upgrading. In this study, mixed sorbents of aqueous porous carbons were developed to separate CO2 from the biogas, where the porous carbon with the developed micropore structure was identified as the most desirable constituent. Both thermodynamics and kinetics were studied experimentally, and Henry’s constant (KH) and the liquid-side mass-transfer coefficient (kL) of CO2 in the mixed sorbent as well as the selectivity of CO2/CH4 were obtained accordingly. Furthermore, the CO2 separation performance was evaluated with a proposed index, and the cost of biogas upgrading using the mixed sorbent was estimated and compared. The results showed that the porous carbon with the developed micropore structure led to better performance on KH and kL of CO2 in the mixed sorbent, and the mixed sorbent with 3.03 wt% porous carbon exhibited the best CO2 separation performance, reducing 36.2 % in cost compared to the current technologies.
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| 6. |
- He, Ming, et al.
(författare)
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A controllable approach for the synthesis of titanate derivatives of potassium tetratitanate fiber
- 2004
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Ingår i: Journal of Materials Science. - 0022-2461 .- 1573-4803. ; 39, s. 3745-3750
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Tidskriftsartikel (refereegranskat)abstract
- Three types titanate derivatives, K2Ti6O13 fiber, K2Ti8O17 fiber and anatase TiO2 fiber, were synthesized by ion-exchange reaction from potassium tetratitanate fiber (K2Ti4O9) based on the hydrate conditions predicted by a thermodynamic model. These products were formed by a heat treatment of the corresponding hydrate intermediates K1.33H0.67Ti4O9·H2O, KHTi4O9·0.5H2O and H2Ti4O9·1.2H2O which were quantitatively obtained by controlling the pH value and the equilibrium concentration of potassium ion. The mole ratio of Ti/K in solid phase (R) of the target products was taken as the controlling aim in the hydrate process. The temperature for heat treatment of hydrate intermediates was determined by thermogravimetry (TG) and differential scanning calorimetry (DSC). All products retained fibrous morphology similar to that of K2Ti4O9 used as the starting material.
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| 7. |
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| 8. |
- Ji, Xiaoyan, et al.
(författare)
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CO2 recovery in Ionic Liquids
- 2013
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Ingår i: Biomass to energy and chemicals. - Jyväskylä : Jyväskylä university. - 9789513954543 - 9789513954550 ; , s. 67-74
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 9. |
- Leng, Yan, et al.
(författare)
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Alterations of Elastic Property of Spastic Muscle With Its Joint Resistance Evaluated From Shear Wave Elastography and Biomechanical Model
- 2019
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Ingår i: Frontiers in Neurology. - : Frontiers Media S.A.. - 1664-2295. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- This study aims to quantify passive muscle stiffness of spastic wrist flexors in stroke survivors using shear wave elastography (SWE) and to correlate with neural and non-neural contributors estimated from a biomechanical model to hyper-resistance measured during passive wrist extension. Fifteen hemiplegic individuals after stroke with Modified Ashworth Scale (MAS) score larger than one were recruited. SWE were used to measure Young's modulus of flexor carpi radialis muscle with joint from 0 degrees (at rest) to 50 degrees flexion (passive stretch condition), with 10 degrees interval. The neural (NC) and non-neural components i.e., elasticity component (EC) and viscosity component (VC) of the wrist joint were analyzed from a motorized mechanical device NeuroFlexor (R) (NF). Combining with a validated biomechanical model, the neural reflex and muscle stiffness contribution to the increased resistance can be estimated. MAS and Fugl-Meyer upper limb score were also measured to evaluate the spasticity and motor function of paretic upper limb. Young's modulus was significantly higher in the paretic side of flexor carpi radialis than that of the non-paretic side (p < 0.001) and it increased significantly from 0 degrees to 50 degrees of the paretic side (p < 0.001). NC, EC, and VC on the paretic side were higher than the non-paretic side (p < 0.05). There was moderate significant positive correlation between the Young's Modulus and EC (r = 0.565, p = 0.028) and VC (r = 0.645, p = 0.009) of the paretic forearm flexor muscle. Fugl-Meyer of the paretic forearm flexor has a moderate significant negative correlation with NC (r = -0.578, p = 0.024). No significant correlation between MAS and shear elastic modulus or NF components was observed. This study demonstrated the feasibility of combining SWE and NF as a non-invasive approach to assess spasticity of paretic muscle and joint in stroke clinics. The neural and non-neural components analysis as well as correlation findings of muscle stiffness of SWE might provide understanding of mechanism behind the neuromuscular alterations in stroke survivors and facilitate the design of suitable intervention for them.
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| 10. |
- Lu, Xiaohua, et al.
(författare)
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Nano-interface enhanced CO2 absorption and mechanism analysis
- 2020
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Ingår i: Huagong Xuebao/CIESC Journal. - : Materials China. - 0438-1157. ; 71:1, s. 34-42
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Tidskriftsartikel (refereegranskat)abstract
- CO2 capture and separation (CCS) is a key step to mitigate greenhouse gas emissions and develop renewable energy. The trade-off between the rate and efficiency in the CO2 separation process cannot be solved with the traditional process intensification. Using nano-interface to realize process intensification has been widely used in the chemical process with multi-phase transfer, and CO2 separation is one of examples. This review summarizes the research work from the establishment of CO2 transfer model at nano-interface and the resistance regulation, the acquisition of the CO2 chemical potentials at equilibrium and at the nano-interface (the driving force regulation) and the molecular simulation analysis of the interface enhancement mechanism. Based on the theoretical studies, the resistance distribution for the CO2 separation process in a real absorption tower is further analyzed and a "three-stage strengthening scheme" is proposed to decrease the investment and operating costs. © All Right Reserved.
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| 11. |
- Ma, Chunyan, et al.
(författare)
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Hybrid solvents based on ionic liquids/deep eutectic solvents for CO2 separation
- 2023
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Ingår i: Science Talks. - : Elsevier. - 2772-5693. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- CO2 separation plays a vital role in reducing CO2 emissions to combat climate change, while the available technologies still face challenges, including high costs and intensive energy usage. It is still critical to develop an energy-efficient and cost-effective technology for CO2 separation. Ionic liquid/deep eutectic solvent (IL/DES) has drawn significant attention in CO2 separation because they are tunable and exhibit high thermal stability and high CO2 solubility. The technologies based on IL/DES show their potential to reduce cost and energy usage. However, their viscosity is relatively high. In our work, adding cosolvents was used to adjust the high viscosity of IL/DES. A universal framework of IL/DES-based hybrid solvents for CO2 separation, from properties determination, thermodynamic modeling, to process design and evaluation, has been built up. Several DESs/ILs interacted with CO2 chemically and/or physically were investigated, aiming for the gas streams with different CO2 concentrations (biogas, flue gas). A detailed comparison of the performance of IL/DES-based hybrid solvents in terms of energy usage and cost with respect to conventional solvents was provided to study their feasibility. Our research shows that IL/DES-based hybrid solvents are promising for CO2 separation for different gas streams to reach the aim of lowing energy usage and cost, while further improvement is still needed to reach a technological breakthrough.
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| 12. |
- Ma, Chunyan, et al.
(författare)
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Modeling, simulation and evaluation of biogas upgrading using aqueous choline chloride/urea
- 2017
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 229:1, s. 1269-1283
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Tidskriftsartikel (refereegranskat)abstract
- Biogas has been considered as an alternative renewable energy, and raw biogas needs to be upgraded in order to be used as vehicle fuels or injected into the natural gas grid. In this work, the conceptual process for biogas upgrading using aqueous choline chloride (ChCl)/urea (1:2 on a molar basis) was developed, simulated and evaluated based on the commercialized software Aspen Plus. Reliable thermophysical properties and phase equilibria are prerequisite for carrying out process simulation. In order to carry out the process simulation, the thermophysical properties of ChCl/Urea (1:2) and its aqueous solutions as well as the phase equilibria of gas-ChCl/Urea (1:2), ChCl/Urea (1:2)-H2O and gas-ChCl/Urea (1:2)-H2O were surveyed and evaluated. After evaluation, the consistent experimental data of these thermophysical properties were fitted to the models embedded in Aspen Plus. The properties needed but without available experimental results were predicted theoretically. The Non-Random Two-Liquid model and the Redlich-Kwong equation (NRTL-RK) model were used to describe the phase equilibria. The equilibrium approach was used for process simulation. Sensitivity analysis was conducted to determine the reasonable operating parameters. With a set of reasonable operating conditions, the effects of ChCl/Urea (1:2) content on the total energy utilization, the diameters and pressure drops of absorber and desorber as well as the environmental assessment of the process were studied. The simulation results showed that, with the addition of ChCl/Urea (1:2), the total energy utilization decreased by 16% compared to the process with pure water, and the diameters of both absorber and desorber decreased with increasing content of ChCl/Urea (1:2). The process using aqueous ChCl/Urea (1:2) was more environmentally benign than that with pure water. Therefore, aqueous ChCl/Urea (1:2) is a promising solvent for biogas upgrading.
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| 13. |
- Peng, Bo, et al.
(författare)
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Geochemistry of major and trace elements and Pb-Sr isotopes of a weathering profile developed on the Lower Cambrian black shales in central Hunan, China
- 2014
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Ingår i: Applied Geochemistry. - : Elsevier BV. - 0883-2927 .- 1872-9134. ; 51, s. 191-203
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports a geochemical study on the major and trace elements and Pb-Sr isotopes of a weathering profile developed in the Lower Cambrian black shales in central Hunan (China). Six weathering horizons were identified and sampled vertically throughout the profile. The chemical composition of the profile consists of variable concentrations of the major elements Fe2O3, FeO, MnO, MgO, CaO, Na2O, and P2O5 and of less variable concentrations of SiO2, TiO2, Al2O3, and K2O. The chemical change caused by weathering is estimated by mass-balance calculations, and the results show that the element mobility is characterised by substantial loss of SiO2, FeO, CaO, K2O, Na2O, LOI, Cr, V, Ba, Cs, Rb, Sr, U, and Th, and moderate loss of Al2O3, MgO, Fe2O3, Ni, Cu, Pb, Tl, Sn, Sc, Ge and REE (Y). The high field strength elements TiO2, Sn, Sc, U, Ga, Ge, Zr, Hf, Nb, and Ta were immobile during weathering. The chemical changes and the Pb-Sr isotopic data suggest that four types of chemical reactions occurred: the oxidation of sulphide minerals (e.g., pyrite) and organic carbon (OS), the dissolution of less resistant clinochlore-Ia, calcite, and P-bearing minerals (DL), the dissolution of detrital albite and microcline (DA), and the transformation of clay (TC) minerals (e.g., muscovite and illite-smectite). These chemical reactions then led to two stages of geochemical processes, an early stage of chemical differentiation and a later stage of chemical homogenisation. The chemical differentiation dominated by the OS, DL, and DA reactions, led to the leaching of mobile elements (e.g., MgO, Na2O, K2O, P2O5, Sr, and REE) and the redistribution of some less mobile elements (e.g., SiO2 and Al2O3). In contrast, the chemical homogenisation, which was caused by TC reactions, led to the leaching of both mobile and less mobile elements from the system and ultimately transformed the weathered black shales into soil. Soils derived from black shales in South China might result from the above two geochemical processes. (C) 2014 Elsevier Ltd. All rights reserved.
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| 14. |
- Sarmad, Shokat, et al.
(författare)
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Screening of Deep Eutectic Solvents (DESs) as green CO2 sorbents : from solubility to viscosity
- 2017
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Ingår i: New Journal of Chemistry. - : Royal Society of Chemistry. - 1144-0546 .- 1369-9261. ; 41:1, s. 290-301
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Tidskriftsartikel (refereegranskat)abstract
- Deep eutectic solvents (DESs) as ionic liquid (IL) analogues show great potential for CO2 capture. They exhibit favorable solvent properties and are considered to be economical alternatives to conventional ILs. In this study, we prepare 35 DESs and screen them in terms of their CO2 solubility and viscosity, both crucial factors to be considered when designing efficient CO2 sorbents. The influence of salt and HBD type and structure, as well their molar ratio on the CO2 solubility and viscosity of the DESs is investigated. The viscosity and CO2 solubility of the DESs are compared with those of other DESs and conventional ILs. 15 DESs, which exhibit comparable CO2 absorption capacity to choline chloride-urea DESs, glycerol DESs and fluorinated ILs, are chosen as the promising ones. The viscosities of the selected DESs are below 200 mPa s and are lower than those of choline chloride-based DESs. Since the viscosity of the DESs is relatively high, on a par with those of conventional ILs, the effect of water as a co-solvent is investigated in order to decrease the viscosity. The addition of water to the glycerol-based DESs improves the kinetics of absorption by decreasing the viscosity, thus increasing the CO2 absorption capacity. Dry or aqueous DESs that demonstrate a high sorption capacity and low viscosity are chosen for additional analysis and characterization, and further functionalization will be carried out in the future to improve their sorption capacityy
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| 15. |
- Sarmad, Shokat, et al.
(författare)
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Screening of Deep Eutectic Solvents (DESs) as green CO2 sorbents : from solubility to viscosity
- 2017
-
Ingår i: New Journal of Chemistry. - : Royal Society of Chemistry. - 1144-0546 .- 1369-9261. ; 41:1, s. 290-301
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Tidskriftsartikel (refereegranskat)abstract
- Deep eutectic solvents (DESs) as ionic liquids (ILs) analogues show great potential in CO2 capture. They exhibit favorable solvent properties and are considered as economical alternatives to conventional ILs. In this study, we prepare 35 DESs and screen in terms of their CO2 solubility and viscosity that are two crucial factors to be considered upon the design of efficient CO2 sorbents. The influence of salt and hydrogen bond donor nature and structure, their molar ratio on the CO2 solubility and viscosity of DESs are investigated. The viscosity and CO2 solubility of the DESs are compared with other DESs or conventional ILs. 15 DESs which exhibit comparable CO2 absorption capacity with those of choline chloride-urea or glycerol DESs or fluorinated ILs, are chosen as promising one. The viscosity of selected DESs are below 200 mPa[middle dot]s and are lower than choline chloride-based DESs. Since the viscosity of DESs is relatively high an par to those of conventional ILs, the effect of water as a co-solvent are investigated in order to decrease the viscosity. The addition of water to high viscosity glycerol-based DESs improves the kinetics of absorption by decreasing the viscosity thus increases the CO2 absorption capacity. Dry or aqueous DESs that demonstrate high sorption capacity and low viscosity are chosen for further analysis and characterization in future and further functionalization will be carried out to improve their sorption capacity.
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| 16. |
- Wu, Nanhua, et al.
(författare)
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Confinement Phenomenon Effect on the CO2 Absorption Working Capacity in Ionic Liquids Immobilized into Porous Solid Supports
- 2017
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 33:42, s. 11719-11726
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the CO2 absorption working capacity and solubility in the ionic liquids immobilized into porous solid materials (substrates) was studied both experimentally and theoretically. The CO2 absorption working capacity in the immobilized ionic liquids was measured experimentally. It was found that the CO2 absorption working capacity and solubility increased up to 10 times compared to that in the bulk ionic liquids when the film thickness is nearly 2.5 nm in the [HMIm][NTf2] immobilized into the P25. Meanwhile, a new model was proposed to describe the Gibbs free energy of CO2 in the immobilized ionic liquids, and both macro- and micro-analyses of the CO2 solubility in the confined ionic liquids were conducted. The theoretical investigations reveal that the substrate has a crucial effect on the gas solubility in the ionic liquid immobilized into the substrates, and the model performance was approved with the consideration of substrate effect.
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| 17. |
- Xie, Wenlong, et al.
(författare)
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CO2 uptake behavior of supported tetraethylenepentamine sorbents
- 2016
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 30:6, s. 5083-5091
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Tidskriftsartikel (refereegranskat)abstract
- Supported tetraethylenepentamine (TEPA) sorbents have been proposed as an attractive alternative for postcombustion carbon capture. To promote the application of these sorbents, in this work, a systematic investigation of CO2 absorption behavior on five TEPA-immobilized sorbents was conducted, in which the effects of TEPA loading, supports, and temperatures on both CO2 absorption working capacity and kinetics were studied. Poly(methyl methacrylate) (PMMA)-TEPA is the best among the studied sorbents. The optimal temperature for PMMA-TEPA was 25 deg lower compared to other sorbents studied in this work, and the maximum CO2 capacity was 0.17 g/g-sorbent. This is the highest value reported to date for PMMA-TEPA sorbents, and one of the high values that have been reported for TEPA-immobilized sorbents. In addition, the working capacity of PMMA-TEPA after six cycles of regeneration was 0.16 g/g-sorbent (i.e., with only 6% decrease). Therefore, PMMA is promising to be used as supporting material for TEPA in CO2 capture. The kinetics analysis with both the Avrami’s fractional-order kinetic model and the mass-transfer model on the basis of nonequilibrium thermodynamics was further conducted and discussed. Besides, it was also found that the CO2 absorption kinetics and capacity were affected by both the pore structure and the surface chemistry of the support.
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| 18. |
- Xie, Wenlong, et al.
(författare)
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Mass Transfer Rate Enhancement for CO2 Separation by Ionic Liquids : Effect of Film Thickness
- 2016
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 55:1, s. 366-372
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Tidskriftsartikel (refereegranskat)abstract
- Ionic liquids (ILs) are promising in CO2 separation, while the film thickness is particularly critical for gas transport in these viscous and expensive liquids. In this work, the influence of IL-film thickness on CO2 absorption/desorption of two different IL immobilized sorbents was investigated, in which the results from the thermogravimetric analyzer were further used to estimate the scale of IL-film thickness. It is found that the IL-film in nanoscale is a prerequisite for efficient CO2 absorption/desorption; the equilibrium time can be 10-times different, and the rate constant can be 100-times different for microscale and nanoscale IL-films. This is the first time to quantitatively reveal the influence of IL-film thickness and find out its scale for a significant rate enhancement in the CO2 absorption/desorption by IL immobilized sorbents
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| 19. |
- Xie, Wenlong, et al.
(författare)
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Mass‐Transfer Rate Enhancement for CO2 Separation by Ionic Liquids: Theoretical Study on the Mechanism
- 2015
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Ingår i: AIChE Journal. - : Wiley. - 0001-1541 .- 1547-5905. ; 61:12, s. 4437-4444
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Tidskriftsartikel (refereegranskat)abstract
- To promote the development of ionic liquid (IL) immobilized sorbents and supported IL membranes (SILMs) for CO2 separation, the kinetics of CO2 absorption/desorption in IL immobilized sorbents was studied using a novel method based on nonequilibrium thermodynamics. It shows that the apparent chemical-potential-based mass-transfer coefficients of CO2 were in three regions with three-order difference in magnitude for the IL-film thicknesses in microscale, 100 nm-scale, and 10 nm-scale. Using a diffusion-reaction theory, it is found that by tailoring the IL-film thickness from microscale to nanoscale, the process was altered from diffusion-control to reaction-control, revealing the inherent mechanism for the dramatic rate enhancement. The extension to SILMs shows that the significant improvement of CO2 flux can be obtained theoretically for the membranes with nanoscale IL-films, which makes it feasible to implement CO2 separation by ILs with low investment cost
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| 20. |
- Xie, Yujiao, et al.
(författare)
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A Thermodynamic Study of Aqueous 1-Allyl-3-Methylimidazolium Formate Ionic Liquid as a Tailored Sorbent for Carbon Dioxide Separation
- 2017
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Ingår i: Energy Technology. - : John Wiley & Sons. - 2194-4296 .- 2194-4288. ; 5:8, s. 1464-1471
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Tidskriftsartikel (refereegranskat)abstract
- In this work, aqueous 1-allyl-3-methylimidazolium formate ([Amim][HCOO]) was studied as a potential sorbent for CO2 separation. The density and viscosity of aqueous [Amim][HCOO] were measured at temperatures ranging from 293.15 to 333.15 K at atmospheric pressure. The solubility of CO2 and CH4 in dry [Amim][HCOO] as well as the CO2 solubility in aqueous [Amim][HCOO] were measured at pressures up to 1.8 MPa and temperatures of 298.2, 313.2, and 333.2 K. The results showed that the density and viscosity of aqueous [Amim][HCOO] as well as the CO2 solubility in aqueous [Amim][HCOO] decreased upon increasing the water concentration and temperature. The viscosity was very sensitive to the water concentration. The experimental density and viscosity of aqueous [Amim][HCOO] were fitted to semiempirical equations, and the excess molar volume and viscosity deviations were calculated to investigate the interaction between the [Amim][HCOO] ionic liquid and water. The experimental vapor–liquid equilibrium was represented with the nonrandom two-liquid and Redlich–Kwong model. The model parameters can be further implemented into Aspen Plus software to conduct process simulations.
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| 21. |
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| 22. |
- Xie, Yujiao, et al.
(författare)
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Effect of Water on the Density, Viscosity, and CO2 Solubility in Choline Chloride/Urea
- 2014
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Ingår i: Journal of Chemical and Engineering Data. - : American Chemical Society (ACS). - 0021-9568 .- 1520-5134. ; 59:11, s. 3344-3352
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Tidskriftsartikel (refereegranskat)abstract
- To study the effect of water on the properties of choline chloride (ChCl)/urea mixtures (1:2 on a molar basis), the density and viscosity of ChCl/urea (1:2) with water were measured at temperatures from 298.15 K to 333.15 K at atmospheric pressure, the CO2 solubility in ChCl/urea (1:2) with water was determined at 308.2 K, 318.2 K, and 328.2 K and at pressures up to 4.5 MPa. The results show that the addition of water significantly decreases the viscosity of ChCl/urea (1:2), whereas the effects on their density and CO2 solubility are much weaker. The CO2 solubility in ChCl/urea (1:2) with water was represented with the Nonrandom-Two-Liquid Redlich–Kwong (NRTL-RK) model. The excess molar volume and excess molar activation energy were further determined. The CO2 absorption enthalpy was calculated and dominated by the CO2 dissolution enthalpy, and the magnitude of the CO2 dissolution enthalpy decreases with the increase of water content.
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| 23. |
- Xie, Yujiao, et al.
(författare)
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Energy consumption analysis for CO2 separation using imidazolium-based ionic liquids
- 2014
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 136, s. 325-335
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Tidskriftsartikel (refereegranskat)abstract
- CO2 solubility in ionic liquids has been measured extensively in order to develop ionic liquid-based technology for CO2 separation. However, the energy consumption analysis has not been investigated well for such technology. In order to carry out the energy consumption analysis for CO2 separation using ionic liquids based on available experimental data, in this work, the experimental data of the CO2 solubility in imidazolium-based ionic liquids at pressures below 10 MPa was surveyed and evaluated by a semi-empirical thermodynamic model firstly. Based on the reliable experimental solubility data, the enthalpy of CO2 absorption was further calculated by the thermodynamic model. The results show that the CO2 absorption enthalpy in the studied ionic liquids is dominated by the enthalpy of CO2 dissolution and the contribution of excess enthalpy increases with increasing CO2 solubility in ionic liquids. The magnitude of the CO2 absorption enthalpy decreases with increasing chain length in cation and strongly depends on the anion of ionic liquids. Furthermore, the energy consumption for a CO2 separation process by pressure swing and/or temperature swing was investigated. For the pressure swing process, the Henry’s constant of CO2 in ionic liquids is an important factor for energy consumption analysis; If CO2 is absorbed at 298 K and 1 MPa and ionic liquid is regenerated by decreasing the pressure to 0.1 MPa at the same temperature, among the studied ionic liquids, [emim][EtSO4] is the solvent with the lowest energy consumption of 9.840 kJ/mol CO2. For the temperature swing process, the heat capacity of ionic liquids plays a more important role; If CO2 is absorbed at 298 K and desorbed at 323 K and 0.1 MPa, [emim][PF6] is the solvent with the lowest energy demand of 888.9 kJ/mol CO2. If the solvent is regenerated by releasing pressure and increasing temperature, both the Henry’s constant of CO2 in ionic liquids and the heat capacity of ionic liquids are important for analyzing the energy consumption; If CO2 is absorbed at 298 K and 1 MPa and ionic liquid is regenerated at 323 K and 0.1 MPa, [bmim][Tf2N] is the solvent with the lowest energy consumption of 57.71 kJ/mol CO2.
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| 24. |
- Xie, Yujiao, et al.
(författare)
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Evaluation of imidazolium-based ionic liquids for biogas upgrading
- 2016
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 175, s. 69-81
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Tidskriftsartikel (refereegranskat)abstract
- The conceptual processes for biogas upgrading using three imidazolium-based ionic liquids ([hmim][Tf2N], [bmim][Tf2N] and [bmim][PF6]) were simulated in Aspen Plus to study the effect of properties of ionic liquids (ILs) on the process performance. To conduct the process simulation, each IL was input into Aspen Plus as a pseudo component, their critical properties were estimated by group contribution method, and their thermo-physical properties were correlated from the available experimental data by semi-empirical equations. The gas solubility in ILs was modeled with the non-random two-liquid model and Redlich–Kwong equation of state. Among the studied ILs, the simulation results show that the amount of recirculated solvents and the total energy consumption for upgrading process using ILs follow: [bmim][Tf2N] < [bmim][PF6] < [hmim][Tf2N]. The effects of density and viscosity of ILs on pressure drop and diameter of the absorber as well as the effects of operational pressures and temperatures on the process efficiency were investigated. It is found that the energy consumption increases with increasing pressure and temperature in the absorber and decreases with increasing pressure in the first flash tank. The ILs-based technology was further compared with water scrubbing and aqueous choline chloride/urea scrubbing, and the comparison shows that the total energy consumptions follow: 50%ChCl/Urea-water < [bmim][Tf2N] scrubbing < water scrubbing
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| 25. |
- Xie, Yujiao, et al.
(författare)
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Solubilities of CO2, CH4, H2, CO and N2 in choline chloride/urea
- 2017
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Ingår i: Green Energy & Environment. - : Elsevier. - 2468-0257. ; 1:3, s. 195-200
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Tidskriftsartikel (refereegranskat)abstract
- Solubilities of CO2, CH4, H2, CO and N2 in choline chloride/urea (ChCl/Urea) were investigated at temperatures ranging from 308.2 to 328.2 K and pressures ranging from 0.6 to 4.6 MPa. The results show that the solubilities of gases increase with increasing pressure and decreasing temperature. The solubility of CO2 is higher than that of CH4, H2, CO and N2, which indicates that ChCl/Urea may be used as a potential solvent for CO2 capture from the gas mixture. Solubility of CO2 in ChCl/Urea was fitted by Non-Random Two-Liquid and Redlich–Kwong (NRTL-RK) model, and solubility of CH4, H2, CO or N2 in ChCl/Urea was fitted by Henry's Law. The standard enthalpy, standard Gibbs energy and standard entropy of gases were calculated. Additionally, the CO2/CH4 selectivities in water, dry ChCl/Urea and aqueous ChCl/Urea were further discussed.
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| 26. |
- Xie, Yujiao, et al.
(författare)
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Techno-economic evaluation of biogas upgrading using ionic liquids in comparison with industrially used technology in Scandinavian anaerobic digestion plants
- 2018
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 227, s. 742-750
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Tidskriftsartikel (refereegranskat)abstract
- The process of biogas upgrading with ionic liquids, i.e. pure 1-butyl-3-methylimidazolium bis(trifluoro-methylsulfonyl)imide ([bmim][Tf2N]), aqueous choline chloride/urea (ChCl/Urea), and aqueous 1-allyl-3-methyl imidazole formate ([Amim][HCOO]), was simulated in Aspen Plus and compared with the conventional water scrubbing upgrading technique. The comparisons of the performances on the amount of recirculated solvents and energy usage show the following order: aqueous [Amim][HCOO]<aqueous ChCl/Urea<[bmim][Tf2N]<water. Six different co-digestion plants (anaerobic digestion, AD, plants) were surveyed to acquire data for comparison. The selected plants had different raw biogas production capacities and produced gas with differing methane content. The data confirmed the simulation results that the type of substrate and the configuration of AD process are two factors affecting energy usage, investment cost, as well as operation and maintenance costs for the subsequent biogas upgrading. In addition, the simulation indicated that the energy usage of the ionic liquid-based upgrading was lower than that of the conventional upgrading techniques in Scandinavian AD plants. The estimated cost including investment, operation and maintenance for the ionic liquid technology showed to be lower than that for the water scrubbing upgrading process.
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| 27. |
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| 28. |
- Xie, Yujiao, et al.
(författare)
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Thermodynamic study on CO2 separation with a novel ionic liquid
- 2015
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Konferensbidrag (refereegranskat)abstract
- 1-allyl-3-methylimidazolium formate ([Amim][HCOO]) exhibited higher solubility for various polysaccharides because of the strong hydrogen bond ability. In this work, the density and viscosity of [Amim][HCOO] were measured at different temperatures, the CO2 and CH4 solubilities in [Amim][HCOO] were determined at temperatures from 298.15 to 333.15 K and at pressures up to 2 MPa. The density and viscosity of [Amim][HCOO] were fitted by semi-empirical equations, and the experimental gas solubility was represented by thermodynamic model. The energy consumption for CO2 separation was calculated and compared with the conventional ILs.
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| 29. |
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| 30. |
- Xu, Jingzhe, et al.
(författare)
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Geochemistry of soils derived from black shales in the Ganziping mine area, western Hunan, China
- 2013
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Ingår i: Environmental Earth Sciences. - : Springer Science and Business Media LLC. - 1866-6280 .- 1866-6299. ; 70:1, s. 175-190
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Tidskriftsartikel (refereegranskat)abstract
- The geochemistry of major and trace elements (including heavy metals and rare earth elements) of the fresh and weathered black shales, and the soils derived from black shales in the Ganziping mine area in western Hunan province (China) were studied using the following techniques: X-ray fluorescence (XRF), inductively coupled plasma mass spectrometer (ICP-MS) and X-ray diffraction (XRD). The results show that the black-shale soils are significantly enriched with Al2O3 and Fe2O3, and depleted of mobile elements CaO, Na2O and K2O. The soils are also highly enriched with heavy metals U, V, Ni, Ba, Cu, Zn and Pb, that may cause potential heavy-metal contamination of the soils. Composition of the soils is homogeneous compared to the weathered black shales, for which the concentrations of major elements except CaO and Na2O, and trace elements except heavy metals (U, V, Ni, Ba, Cu, Zn and Pb) as well as the mobile Sr, show lower variations than in the weathered black shales. Ratios of Zr/Hf, Ta/Nb, Y/Ho, Nd/Sm, and Ti/(Ti + Zr), of the soils are also less variable, with values constantly similar to that of the fresh and weathered black shales correspondingly. Thus, components of the soils are believed to be contributed from the parent black shales through weathering and pedogenesis. It is concluded that the soils were formed by at least two stages of geochemical processes: the early stage of chemical differentiation and the later stage of chemical homogenization. The chemical differentiation that was taken during black-shale weathering might have caused the depletion of CaO and Na2O, and the enrichment of Al2O3 and Fe2O3; while the chemical homogenization that was taken during pedogenesis led to the depletion of SiO2 and K2O, and to the further enrichment of Al2O3 and Fe2O3. The heavy-metal enrichment (contamination) of the soils was then genetically related to the enrichment of Al2O3 and Fe2O3 in the soils.
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| 31. |
- Yu, Changxun, et al.
(författare)
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Effect of weathering on abundance and release of potentially toxic elements in soils developed on Lower Cambrian black shales, P. R. China
- 2012
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Ingår i: Environmental Geochemistry and Health. - : Springer. - 0269-4042 .- 1573-2983. ; 34:3, s. 375-390
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Tidskriftsartikel (refereegranskat)abstract
- This paper examines the geochemical features of 8 soil profiles developed on metalliferous black shales distributed in the central parts of the South China black shale horizon. The concentrations of 21 trace elements and 8 major elements were determined using ICP-MS and XRF, respectively, and weathering intensity (W) was calculated according to a new technique recently proposed in the literature. The data showed that the black shale soils inherited a heterogeneous geochemical character from their parent materials. A partial least square regression model and EFbedrock (enrichment factor normalized to underlying bedrock) indicated that W was not a major control in the redistribution of trace metals. Barium, Sn, Cu, V, and U tended to be leached in the upper soil horizons and trapped by Al and Fe oxides, whereas Sb, Cd, and Mo with negative EF values across the whole profiles may have been leached out during the first stage of pedogenesis (mainly weathering of black shale). Compared with the Chinese average soils, the soils were strongly enriched in the potentially toxic metals Mo, Cd, Sb, Sn, U, V, Cu, and Ba, among which the 5 first listed were enriched to the highest degrees. Elevated concentrations of these toxic metals can have a long-term negative effect on human health, in particular, the soils in mining areas dominated by strongly acidic conditions. As a whole, the black shale soils have much in common with acid sulfate soils. Therefore, black shale soils together with acid sulfate soils deserve more attention in the context of metal exposure and human health.
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| 32. |
- Zhang, Yingying, et al.
(författare)
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Energy Consumption Analysis for CO2 Separation from Gas Mixtures with Liquid Absorbents
- 2014
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 61, s. 2695-2698
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Tidskriftsartikel (refereegranskat)abstract
- CO2 separation is an energy intensive process, and it plays an important role in both energy saving and CO2 capture and storage (CCS) to deal with global-warming. CO2 can be from different sources in a wide temperature, pressure and concentrations range. Meanwhile, new liquid absorbents are under-development to cost-effectively separate CO2 from gas mixtures. All this makes it crucial to analyze the energy consumption for CO2 separation from different streams and with different absorbents. In this work, the theoretical energy consumption of CO2 separation from flue gas (CO2/N2), lime kiln gas (CO2/N2), biogas (CO2/CH4) and bio-syngas (CO2/H2/CO) was calculated. The results show that the energy consumption of CO2 separation from flue gas is the highest and that from biogas is the lowest. If the CO2 captured from flue gases was substituted by that from biogases, the energy saving would be equivalent to 28.13 million ton standard coal globally. The energy consumption of CO2 separation from biogas using traditional absorbent of 30%MEA and new developed ionic liquids (ILs) was further studied, in which 1-ethyl-3-methy- limidazolium bis[(trifluoromethyl)sulfonyl]imide ([Emim][NTf2]), 1-butyl-3-methylimida- zolium tetrafluoroborate ([Bmim][BF4]), 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide ([Hmim][Tf2N]) and 1-butyl-1-methylpyrrolidinium bis[(trifluoromethyl)sulfonyl]imide ([Bmpy][Tf2N]) were screened from 75 ILs. The energy consumptions of CO2 separation using ILs are lower than those of 30%MEA and that of [Bmim][BF4] is the lowest in the four screened ILs. With a very low vapor pressure and high CO2 solubility, it's promising to use ILs as absorbents for CO2 separation.
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| 33. |
- Zhang, Yingying, et al.
(författare)
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Screening of conventional ionic liquids for carbon dioxide capture and separation
- 2016
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 162, s. 1160-1170
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Tidskriftsartikel (refereegranskat)abstract
- CO2 capture and storage could efficiently mitigate CO2 emissions, wherein CO2 capture is a crucial energy-intensive process. Ionic liquids (ILs) have been proposed as potential liquid absorbents for CO2 separation. The CO2 absorption capacity and selectivity of ILs have also been investigated extensively. Although ILs have been screened for CO2 separation, only specific ILs have been examined in terms of energy consumption. In this study, 76 conventional ILs were collected and screened in terms of energy consumption to establish potential ILs for CO2 separation. Seventeen ILs were screened according to the CO2 dissolution enthalpy and CO2 working capacity criteria obtained from the Henry’s law constant in the preliminary screening. Seven ILs were then screened from the 17 ILs according to the CO2 working capacity from the measured CO2 solubility in the final screening. The energy consumptions of the seven screened ILs (i.e., [Emim][NTf2], [Bmim][BF4], [Bmim][PF6], [Bmim][NTf2], [Hmim][NTf2], [Bmpy][NTf2], and [Hmpy][NTf2]) were calculated, and the corresponding gas solubility selectivities were discussed. The energy consumptions and properties of the seven screened ILs were compared with those of the commercial CO2 absorbents of 30 wt% MEA, 30 wt% MDEA, and dimethyl ethers of polyethylene glycol (Selexol™ or Coastal AGR®). The results showed that the energy consumptions of the seven screened ILs were lower than those of the commercial CO2 absorbents. [Hmpy][NTf2] showed the lowest energy consumption among the seven screened ILs under the operating conditions set in this study.
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| 34. |
- Zhang, Yingying, et al.
(författare)
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Thermodynamic analysis of CO2 separation from biogas with conventional ionic liquids
- 2018
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 217, s. 75-87
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Tidskriftsartikel (refereegranskat)abstract
- CO2 separation plays an important role in energy saving and CO2 emission reduction to address global warming. Ionic liquids (ILs) have been proposed as potential absorbents for CO2 separation, and a large amount of ILs have been synthesized to achieve this purpose. To screen ILs for CO2 separation, CO2 absorption capacity/selectivity and energy use have been considered, whereas the required amount of IL has been seldom involved. In this work, CO2 separation from biogas with 30 conventional ILs was analyzed theoretically on the basis of the Gibbs free energy change combining the amount of IL needed and the energy use. The desorption temperature was estimated from the absorption pressure, and then the amount of IL needed and the energy use were calculated. Thermodynamic analysis shows that the absorption pressure and the desorption temperature need to be changed to achieve optimal separation. Several ILs were screened with certain criteria, namely, the amount of IL needed and energy use. The performance of the screened ILs was compared with that of commercial CO2 absorbents (30 wt% MEA, 30 wt% MDEA, DEPG, and water). The comparison with DEPG and water shows that the screened physical ILs are promising for IL-based technologies because of their advantages of negligible vaporization enthalpy, low amount of absorbent needed, or low energy use. A comparison with 30 wt% MEA and 30 wt% MDEA indicates that chemical IL has negligible vaporization enthalpy and low energy use. These findings show that the screened ILs are promising for CO2 separation from biogas.
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| 35. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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