Limestone can be used for CO_2 capture and sequestration(CCS) in flue gas effectively. However, its CCS capability will dramatically decline after several cycles due to the surface "sintering". In this work,...Limestone can be used for CO_2 capture and sequestration(CCS) in flue gas effectively. However, its CCS capability will dramatically decline after several cycles due to the surface "sintering". In this work, the limestone was modified with palygorskite to reduce sintering phenomenon between the absorbent particles during the CCS process and the carbonation rate of the limestone can be enhanced effectively. Palygorskite is a natural mineral with nano-fibrous structure which can reduce the mutual contact of limestone particles during the CCS process. The results were detected by TGA, SEM, MIP, FTIR and particle size analyzer respectively. The best CO_2 capture performance of modified absorbent was 13.11% improvement with only 5 wt% palygorskite added during the CCS process after 15 cycles compared with natural absorbent. It was found that excellent microscopic structures of absorbent modified with palygorskite was created, and the surface sintering was postponed leading to CO_2 capture performance enhanced under the same conditions.展开更多
The objective of this work is to study the influences of silica supports and PEG additive on the sorption performance of molecular basket sorbent(MBS) for CO_2 capture consisting of polyethylenimine and one of the fol...The objective of this work is to study the influences of silica supports and PEG additive on the sorption performance of molecular basket sorbent(MBS) for CO_2 capture consisting of polyethylenimine and one of the following supports: SBA-15(2-D structure), TUD-1(3-D sponge-like structure) and fumed silica HS-5(3-D disordered structure). Effects of the supports regarding pore structures and pore properties, the PEI loading amount as well as the sorption temperature were examined. Furthermore, polyethylene glycol(PEG) was introduced as an additive into the sorbents and its effect was investigated at different PEI loadings and sorption temperatures. The results suggest that the pore properties of MBS(after PEI loading) play a more important role in the CO_2 sorption capacity, rather than those of the supports alone.MBS with 3D pore structure exhibits higher CO_2 sorption capacity and amine efficiency than those with 2D-structured support. Among the sorbents studied, fumed silica(HS-5) based MBS showed the highest CO_2 sorption capacity in the temperature range of 30-95 °C, probably due to its unique interstitial pores formed by the aggregation of polymer-loaded SiO_2 particles. It was found that the temperature dependence is directly related to the PEI surface coverage layers. The more PEI surface coverage layers, the higher diffusion barrier for CO_2 and the stronger temperature dependence of CO_2 capacity. 3D MBS exceeds 2D MBS at the same PEI coverage layers due to lower diffusion barrier. Adding PEG can significantly enhance the CO_2 sorption capacity and improve amine efficiency of all MBS, most likely by alleviating the diffusion barrier within PEI bulk layers through the inter-molecular interaction between PEI and PEG.展开更多
Highly porous nitrogen-doped carbon materials were synthesized by the carbonization of a low-cost porous covalent triazine polymer, PCTP-3, which had been synthesized by the AlCl_3 catalyzed FriedelCrafts reaction of ...Highly porous nitrogen-doped carbon materials were synthesized by the carbonization of a low-cost porous covalent triazine polymer, PCTP-3, which had been synthesized by the AlCl_3 catalyzed FriedelCrafts reaction of readily available monomers. The nature of the bond and structure of the resulting materials were confirmed using various spectroscopic methods, and the effects of KOH activation on the textural properties of the porous carbon materials were also examined. The KOH-activated porous carbon(aPCTP-3c) materials possessed a high surface area of 2271 m^2 g^(-1) and large micro/total pore volumes of 0.87/0.95 cm^3 g^(-1), respectively, with narrower micropore size distributions than the porous carbon prepared without activation(PCTP-3c). The aPCTP-3c exhibited the best CO_2 uptakes of 284.5 and 162.3 mg g^(-1) and CH_4 uptakes of 39.6 and 25.9 mg g^(-1) at 273 and 298 K/1 bar, respectively, which are comparable to the performance of some benchmark carbon materials under the same conditions. The prepared materials exhibited high CO_2/N_2 selectivity and could be regenerated easily.展开更多
This work presents a simulation study of several Ca-Cu looping variants with CO(2)capture,aiming at both parameter optimization and exergy analysis of these Ca-Cu looping systems.Three kinds of Ca-Cu looping are consi...This work presents a simulation study of several Ca-Cu looping variants with CO(2)capture,aiming at both parameter optimization and exergy analysis of these Ca-Cu looping systems.Three kinds of Ca-Cu looping are considered:(1)carbonation-calcination/reduction-oxidation;(2)carbonation-oxidation-calcination/reduction and (3)carbona tion/oxidation-calcination/reduction.A conventional Ca looping is also simulated for comparison.The influences of the calcination temperature on the mole fractions of CO(2)and CaO at the calciner outlet,the CaCO3 flow rate on the carbonator performance and the Cu/Ca ratio on the calciner performance are analyzed.The second kind of Ca-Cu looping has the highest carbonation conversion.At 1×10^5 Pa and 820℃,complete decomposition of CaCO3 can be achieved in three Ca-Cu looping systems,while the operation condition of 1×10^5 Pa,840℃is required for the conventional Ca looping system.Furthermore,the Cu/Ca molar ratio of 5.13-5.19 is required for the Ca-Cu looping.Exergy analyses show that the maximum exergy destruction occurs in the calciner for the four modes and the second Ca-Cu looping system(i.e.,carbonation-oxidation-calcination/reduction)performs the highest exergy efficiency,up to 65.04%,which is about 30%higher than that of the conventional Ca looping.展开更多
Capacity and kinetics of CO_2 capture of Na_2CO_3 were studied to determine the mechanism for CO_2 sequestration under ambient conditions. Bicarbonate formation of Na_2CO_3 was examined by a thermogravimetric analysis...Capacity and kinetics of CO_2 capture of Na_2CO_3 were studied to determine the mechanism for CO_2 sequestration under ambient conditions. Bicarbonate formation of Na_2CO_3 was examined by a thermogravimetric analysis(TGA) under various CO_2 and water vapor concentrations and the accompanying structural changes of Na_2CO_3 were demonstrated by X-ray diffraction(XRD). Morphological variations were observed during the reaction of CO_2 capture through scanning electron microscope(SEM). Structural changes and morphological variations, which occurred during the course of the reaction, were then connected to the kinetic and exothermic properties of the CO_2 capture process from the XRD and SEM measurements. The results showed that the bicarbonate formation of Na_2CO_3 has two different pathways.For higher CO_2 and H_2O concentrations, the bicarbonate formation proceeded effectively. However, for lower CO_2 and H_2O concentrations, the reactions were more complicated. The formation of Na_2CO_3·H_2O from Na_2CO_3 as the first step, followed by the subsequent formation of Na_5H_3(CO_3)_4, and then the bicarbonate formation proceeds. To understand such fundamental properties in CO_2 capture of Na_2CO_3 is very important for utilization of Na_2CO_3 as a sorbent for CO_2 capture.展开更多
Due to a lack of technology,smaller breweries simply dump excess CO2 into the atmosphere,fueling the greenhouse effect and global warming.State-of-the-art CO2 capture technologies using nanofibrillated cellulose are e...Due to a lack of technology,smaller breweries simply dump excess CO2 into the atmosphere,fueling the greenhouse effect and global warming.State-of-the-art CO2 capture technologies using nanofibrillated cellulose are expensive and require laborious freeze-drying.Consequently,there is a high demand for affordable alternatives in order to reduce the environmental impact in this industry sector.This work describes a novel route for a quick and cost-efficient synthesis of amine-functionalized cellulose pellets by a surfactantassisted steam explosion process.Typical values with this method were porosity of 92%and density of 67 g/cm^3.Investigations on polyethylenimine(PEI)content and distribution revealed a maximum PEI concentration of 20 wt%with decreasing concentration to the core of a pellet.Sufficient stability against brewery exhaust gas was determined and CO2 release at^120℃ could be confirmed.Capacity tests under simulated working conditions with a novel laboratory reactor yielded a CO2 capacity of 1.0 mmol/g or 67 mol/m^3,which is comparable to values known from the literature for other cellulose-based adsorbents.展开更多
Sorbents for CO_2 capture have been prepared by wet impregnation of a commercial active carbon(Ketjen-black, Akzo Nobel) with two CO_2-philic compounds, polyethylenimine(PEI)and tetraethylenepentamine(TEPA), respectiv...Sorbents for CO_2 capture have been prepared by wet impregnation of a commercial active carbon(Ketjen-black, Akzo Nobel) with two CO_2-philic compounds, polyethylenimine(PEI)and tetraethylenepentamine(TEPA), respectively. The effects of amine amount(from 10 to70 wt.%), CO_2 concentration in the feed, sorption temperature and gas hourly space velocity on the CO_2 capture performance have been investigated. The sorption capacity has been evaluated using the breakthrough method, with a fixed bed reactor equipped with on line gas chromatograph. The samples have been characterized by N_2 adsorption–desorption,scanning electron microscopy and energy dispersive X-ray(SEM/EDX). A promising CO_2 sorption capacity of 6.90 mmol/gsorbenthas been obtained with 70 wt.% of supported TEPA at 70℃ under a stream containing 80 vol% of CO_2. Sorption tests, carried out with simulated biogas compositions(CH_4/CO_2mixtures), have revealed an appreciable CO_2 separation selectivity; stable performance was maintained for 20 adsorption–desorption cycles.展开更多
To find potential zeolitic imidazolate frameworks(ZIFs)for CO2 capture from flue gas,we built 169,898 ZIF models from 84,949 hypothetical zeolite networks.By calculating their lattice energies,accessible volumes to CO...To find potential zeolitic imidazolate frameworks(ZIFs)for CO2 capture from flue gas,we built 169,898 ZIF models from 84,949 hypothetical zeolite networks.By calculating their lattice energies,accessible volumes to CO2,the isosteric adsorption heat(Qst)of H2 O,Henry’s constant ratio(SKH)of CO2/N2,percent regenerability(R%),CO2 working capacity(ΔNCO2),CO2/N2 adsorption selectivity(SCO2/N2))and adsorbent performance score(APS),we identi fied 49 hydrophobic ZIF structures that might outplay already-realised ZIFs built from the same imidazolate linkers for CO2 capture from flue gas.展开更多
Herein we report a systematical investigation on the promoting effect of the carbon chain length of the intercalated carboxylic anions on the CO_2 capture performance of Mg-Al layer double hydroxides(LDHs).A series of...Herein we report a systematical investigation on the promoting effect of the carbon chain length of the intercalated carboxylic anions on the CO_2 capture performance of Mg-Al layer double hydroxides(LDHs).A series of organo-LDHs were successfully synthesized via co-precipitation and calcination-rehydration methods. All as-prepared samples were characterized by many techniques including XRD, ATR-FTIR, BET,and TGA. The XRD and ATR-FTIR studies indicated that organic anions were successfully intercalated into LDHs. The influence of some important parameters such as calcination temperature, adsorption temperature, and coating with(Li-Na-K)NO_3 molten salt was investigated. The results exhibited that when the number of carbon is greater than 10, the CO_2 capture capacity steadily increased with the increase in carbon number. After coating with 55 mol%(Li-Na-K)NO_3 molten salt, the CO_2 uptake of LDH-C16 sample with high Mg/Al ratios can be increased up to 3.25 mmol/g. The CO_2 adsorption/desorption cycling stability was also studied using temperature swing adsorption, which showed a stable CO_2 capture performance even after 22 cycles. Considering its high CO_2 capture capacity and good cycling stability, this novel CO_2 adsorbent is very promising in the sorption-enhanced water gas shift(SEWGS) processes.展开更多
Amine-silica composite materials for post-combustion CO_2 capture have attracted considerable attention because of their high CO_2 uptake at low CO_2 concentrations, excellent CO_2 capture selectivity in the presence ...Amine-silica composite materials for post-combustion CO_2 capture have attracted considerable attention because of their high CO_2 uptake at low CO_2 concentrations, excellent CO_2 capture selectivity in the presence of moisture, and lower energy requirements for sorbent regeneration. This review discusses the recent advances in amine-silica composites for CO_2 capture, including adsorbent preparation and characterization, CO_2 capture under dry and moisture conditions at different CO_2 partial pressures, sorbent regeneration, and stability after many cyclic sorption-desorption runs.展开更多
Porous carbon spheres are prepared by direct carbonization of potassium salt of resorcinol-formaldehyde resin spheres, and are investigated as CO_2 adsorbents. It is found that the prepared carbon materials still main...Porous carbon spheres are prepared by direct carbonization of potassium salt of resorcinol-formaldehyde resin spheres, and are investigated as CO_2 adsorbents. It is found that the prepared carbon materials still maintain the typical spherical shapes after the activation, and have highly developed ultra-microporosity with uniform pore size, indicating that almost the activation takes place in the interior of the polymer spheres. The narrow-distributed ultra-micropores are attributed to the "in-situ homogeneous activation"effect produced by the mono-dispersed potassium ions as a form of -OK groups in the bulk of polymer spheres. The CS-1 sample prepared under a KOH/resins weight ratio of 1 shows a very high CO_2 capture capacity of 4.83 mmol/g and good CO_2/N_2 selectivity of ~17-45. We believe that the presence of a welldeveloped ultra-microporosity is responsible for excellent CO_2 sorption performance at room temperature and ambient pressure.展开更多
A membrane contactor using ionic liquids(ILs) as solvent for pre-combustion capture CO_2 at elevated temperature(303-393 K) and pressure(20 bar) has been studied using mathematic model in the present work. A comprehen...A membrane contactor using ionic liquids(ILs) as solvent for pre-combustion capture CO_2 at elevated temperature(303-393 K) and pressure(20 bar) has been studied using mathematic model in the present work. A comprehensive two-dimensional(2 D) mass-transfer model was developed based on finite element method. The effects of liquid properties, membrane configurations, as well as operation parameters on the CO_2 removal efficiency were systematically studied. The simulation results show that CO_2 can be effectively removed in this process. In addition, it is found that the liquid phase mass transfer dominated the overall mass transfer. Membranes with high porosity and small thickness could apparently reduce the membrane resistance and thus increase the separation efficiency. On the other hand, the membrane diameter and membrane length have a relatively small influence on separation performance within the operation range.展开更多
Using the ionic liquid[emim][Tf2N]as a physical solvent,it was found by Aspen Plus simulation that it was possible to attempt to capture CO2 from the flue gas discharged from the coal-fired unit of the power plant.Usi...Using the ionic liquid[emim][Tf2N]as a physical solvent,it was found by Aspen Plus simulation that it was possible to attempt to capture CO2 from the flue gas discharged from the coal-fired unit of the power plant.Using the combination of model calculation and experimental determination,the density,isostatic heat capacity,viscosity,vapor pressure,thermal conductivity,surface tension and solubility of[emim][Tf2N]were obtained.Based on the NRTL model,the Henry coefficient and NRTL binary interaction parameters of CO2 dissolved in[emim][Tf2N]were obtained by correlating[emim][Tf2N]with the gas–liquid equilibrium data of CO2.Firstly,the calculated relevant data is imported into Aspen Plus,and the whole process model of the ionic liquid absorption process is established.Then the absorption process is optimized according to the temperature distribution in the absorption tower to obtain a new absorption process.Finally,the density,constant pressure heat capacity,surface tension,thermal conductivity,and viscosity of[emim][Tf2N]were changed to investigate the effect of ionic liquid properties on process energy consumption,solvent circulation and heat exchanger design.The results showed that based on the composition of the inlet gas stream to the absorbers,CO2 with a capture rate of 90%and a mass purity higher than 99.5%was captured.These results indicate that the[emim][Tf2N]could be used as a physical solvent for CO2 capture from coal-fired units.In addition,the results will provide a theoretical basis for the design of new ionic liquids for CO2 capture.展开更多
In order to study the effects of nanoparticles on the CO_2 absorption in ammonia,nanofluids with different ammonia concentration and different nanoparticle solid loading were prepared by a two-step method.The nanoflui...In order to study the effects of nanoparticles on the CO_2 absorption in ammonia,nanofluids with different ammonia concentration and different nanoparticle solid loading were prepared by a two-step method.The nanofluids-enhanced gas absorption test devices were also established. The CO_2 absorption in TiO_2,CuO,SiO_2 nanofluids,which nanoparticles solid loading were 1. 0-8. 0 g/L,was tested respectively. In comparison with the blank absorption experiment,the effects of nanoparticle solid loading,nanoparticle types,ammonia concentration on the removal efficiency and removal rate were obtained. Experimental results show that adding nanoparticles can enhance the removal efficiency and removal rate,which increase first and then decrease with the increase of nanoparticle solid loading,and there exists an optimum solid loading of TiO_2 nanoparticles. The effect of SiO_2 nanofluid is inhibitory on the reaction. The enhancement factor of CuO nanofluid is always hovering around 1,which does not show the obvious enhancement or inhibition on the reaction. The optimum solid loading decreases gradually with the increase of ammonia concentration. In addition,according to the experimental results,the mechanism of enhanced absorption was analyzed theoretically.展开更多
The globally increasing concentrations of greenhouse gases in atmosphere after combustion of coal-or petroleum-based fuels give rise to tremendous interest in searching for porous materials to efficiently capture carb...The globally increasing concentrations of greenhouse gases in atmosphere after combustion of coal-or petroleum-based fuels give rise to tremendous interest in searching for porous materials to efficiently capture carbon dioxide(CO_2) and store methane(CH4), where the latter is a kind of clean energy source with abundant reserves and lower CO_2 emission. Hundreds of thousands of porous materials can be enrolled on the candidate list, but how to quickly identify the really promising ones, or even evolve materials(namely, rational design high-performing candidates) based on the large database of present porous materials? In this context, high-throughput computational techniques, which have emerged in the past few years as powerful tools, make the targets of fast evaluation of adsorbents and evolving materials for CO_2 capture and CH_4 storage feasible. This review provides an overview of the recent computational efforts on such related topics and discusses the further development in this field.展开更多
Although not everybody wants to admit,climate change has been happening with irreversible consequences.It is getting worse and worse and becoming more and more influential to not only the environment but also to all k...Although not everybody wants to admit,climate change has been happening with irreversible consequences.It is getting worse and worse and becoming more and more influential to not only the environment but also to all kinds of beings;our earth is now seriously threatened by climate change.It is a critical issue the whole society must face and actions must展开更多
Hybrid adsorbents for CO_2 capture were prepared by coassembling laponite(LP) nanosheets and 1-nbutyl-3-methylimidazolium chloride(BMIMCl). The prepared BMIMCl/LP layered hybrids were systematically characterized. The...Hybrid adsorbents for CO_2 capture were prepared by coassembling laponite(LP) nanosheets and 1-nbutyl-3-methylimidazolium chloride(BMIMCl). The prepared BMIMCl/LP layered hybrids were systematically characterized. The interlayer distance of the BMIMCl/LP layered hybrids expanded with an increasing concentration of BMIMCl, indicating that cumulative BMIMCl was intercalated into the LP layers. The efficiency of BMIMCl toward CO_2 capture was significantly enhanced after it was immobilized within LP layers.展开更多
A mechanistic model is developed to investigate the influence of an activator on the corrosion rate of carbon steel in the absorption processes of carbon dioxide(CO2).Piperazine(PZ)is used as the activator in diethano...A mechanistic model is developed to investigate the influence of an activator on the corrosion rate of carbon steel in the absorption processes of carbon dioxide(CO2).Piperazine(PZ)is used as the activator in diethanolamine(DEA)aqueous solutions.The developed model for corrosion takes into consideration the effect of fluid flow,transfer of charge and diffusion of oxidizing agents and operating parameters like temperature,activator concentration,CO2 loading and pH.The study consists of two major models:Vapor–liquid Equilibrium(VLE)model and electrochemical corrosion model.The electrolyte-NRTL equilibrium model was used for determination of concentration of chemical species in the bulk solution.The results of speciation were subsequently used for producing polarization curves and predicting the rate of corrosion occurring at the surface of metal.An increase in concentration of activator,increases the rate of corrosion of carbon steel in mixtures of activated DEA.展开更多
In this work, CaO-NiO mixed oxide powders were evaluated as consecutive CO_2 chemisorbents and catalytic materials for hydrogen production thought the CH_4 reforming process. Between the NiO impregnated CaO and CaO-Ni...In this work, CaO-NiO mixed oxide powders were evaluated as consecutive CO_2 chemisorbents and catalytic materials for hydrogen production thought the CH_4 reforming process. Between the NiO impregnated CaO and CaO-NiO mechanical composite, the first one presented better chemical behaviors during the CO_2 capture and CH_4 reforming processes, obtaining syngas(H_2+ CO) as final product. Results showed that syngas was produced at two different temperature ranges, between 400 and 600 °C and at T > 800 °C, where the first temperature range corresponds to the CH_4 reforming process but the second temperature range was attributed to a different catalytic reaction process: CH_4 partial oxidation. These results were confirmed through different isothermal and cyclic experiments as well as by XRD analysis of the final catalytic products, where the nickel reduction was evidenced. Moreover, when a CO-O_2 flow was used during the carbonation process a triple process was achieved:(i) CO oxidation,(ii) CO_2 chemisorption and(iii) CH_4 reforming. Using this gas flow the hydrogen production was always higher than that obtained with CO_2.展开更多
The effect of CO_2 partial pressure was evaluated during the CO_2 chemisorption in penta lithium aluminate(Li_5AlO_4), using different CO_2 and O_2 partial pressures in the presence or absence of alkaline carbonates. ...The effect of CO_2 partial pressure was evaluated during the CO_2 chemisorption in penta lithium aluminate(Li_5AlO_4), using different CO_2 and O_2 partial pressures in the presence or absence of alkaline carbonates. Results showed that using low PO_2(0.1) did not affect the kinetic and final CO_2 chemisorption process. Moreover, small additions of oxygen(PO_2= 0.05) into the mixture flue gas, seemed to increase the CO_2 chemisorption. Additionally, the presence of alkaline carbonates modified the CO_2 capture temperature range. CO_2 chemisorption kinetic parameters were determined assuming a double exponential model where direct CO_2 chemisorption and CO_2 chemisorption controlled by diffusion processes are considered.Finally, ionic diffusion was analyzed by ionic conduction analysis, where all the gravimetric and ionic measurements were in good agreement showing different diffusion processes depending on temperature.Finally, the oxygen and alkaline carbonate additions have positive effects during the CO_2 chemisorption process in Li_5AlO_4, and a possible reaction mechanism is presented.展开更多
基金Supported by the National Natural Science Foundation of China(51274159)Special Funds for The Major Science and Technology Innovation of Shaanxi Province(2012zkc06-2)
文摘Limestone can be used for CO_2 capture and sequestration(CCS) in flue gas effectively. However, its CCS capability will dramatically decline after several cycles due to the surface "sintering". In this work, the limestone was modified with palygorskite to reduce sintering phenomenon between the absorbent particles during the CCS process and the carbonation rate of the limestone can be enhanced effectively. Palygorskite is a natural mineral with nano-fibrous structure which can reduce the mutual contact of limestone particles during the CCS process. The results were detected by TGA, SEM, MIP, FTIR and particle size analyzer respectively. The best CO_2 capture performance of modified absorbent was 13.11% improvement with only 5 wt% palygorskite added during the CCS process after 15 cycles compared with natural absorbent. It was found that excellent microscopic structures of absorbent modified with palygorskite was created, and the surface sintering was postponed leading to CO_2 capture performance enhanced under the same conditions.
基金the support of this work at Penn State by the U.S.Department of Energy,National Energy Technology Laboratorythe financial support by the China Scholarship Council,the Natural Science Foundation of China(No.51176034)the Open Fund of Key Laboratory of Coal-Based CO2 Capture and Geological Storage of Jiangsu Province(2016A05)
文摘The objective of this work is to study the influences of silica supports and PEG additive on the sorption performance of molecular basket sorbent(MBS) for CO_2 capture consisting of polyethylenimine and one of the following supports: SBA-15(2-D structure), TUD-1(3-D sponge-like structure) and fumed silica HS-5(3-D disordered structure). Effects of the supports regarding pore structures and pore properties, the PEI loading amount as well as the sorption temperature were examined. Furthermore, polyethylene glycol(PEG) was introduced as an additive into the sorbents and its effect was investigated at different PEI loadings and sorption temperatures. The results suggest that the pore properties of MBS(after PEI loading) play a more important role in the CO_2 sorption capacity, rather than those of the supports alone.MBS with 3D pore structure exhibits higher CO_2 sorption capacity and amine efficiency than those with 2D-structured support. Among the sorbents studied, fumed silica(HS-5) based MBS showed the highest CO_2 sorption capacity in the temperature range of 30-95 °C, probably due to its unique interstitial pores formed by the aggregation of polymer-loaded SiO_2 particles. It was found that the temperature dependence is directly related to the PEI surface coverage layers. The more PEI surface coverage layers, the higher diffusion barrier for CO_2 and the stronger temperature dependence of CO_2 capacity. 3D MBS exceeds 2D MBS at the same PEI coverage layers due to lower diffusion barrier. Adding PEG can significantly enhance the CO_2 sorption capacity and improve amine efficiency of all MBS, most likely by alleviating the diffusion barrier within PEI bulk layers through the inter-molecular interaction between PEI and PEG.
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(grant number:2015042434)the support by the Korea Research Fellowship Program(grant number:2017H1D3A1A02013620)
文摘Highly porous nitrogen-doped carbon materials were synthesized by the carbonization of a low-cost porous covalent triazine polymer, PCTP-3, which had been synthesized by the AlCl_3 catalyzed FriedelCrafts reaction of readily available monomers. The nature of the bond and structure of the resulting materials were confirmed using various spectroscopic methods, and the effects of KOH activation on the textural properties of the porous carbon materials were also examined. The KOH-activated porous carbon(aPCTP-3c) materials possessed a high surface area of 2271 m^2 g^(-1) and large micro/total pore volumes of 0.87/0.95 cm^3 g^(-1), respectively, with narrower micropore size distributions than the porous carbon prepared without activation(PCTP-3c). The aPCTP-3c exhibited the best CO_2 uptakes of 284.5 and 162.3 mg g^(-1) and CH_4 uptakes of 39.6 and 25.9 mg g^(-1) at 273 and 298 K/1 bar, respectively, which are comparable to the performance of some benchmark carbon materials under the same conditions. The prepared materials exhibited high CO_2/N_2 selectivity and could be regenerated easily.
基金financially supported by National Key R&D Program of China(2019YFE0100100)。
文摘This work presents a simulation study of several Ca-Cu looping variants with CO(2)capture,aiming at both parameter optimization and exergy analysis of these Ca-Cu looping systems.Three kinds of Ca-Cu looping are considered:(1)carbonation-calcination/reduction-oxidation;(2)carbonation-oxidation-calcination/reduction and (3)carbona tion/oxidation-calcination/reduction.A conventional Ca looping is also simulated for comparison.The influences of the calcination temperature on the mole fractions of CO(2)and CaO at the calciner outlet,the CaCO3 flow rate on the carbonator performance and the Cu/Ca ratio on the calciner performance are analyzed.The second kind of Ca-Cu looping has the highest carbonation conversion.At 1×10^5 Pa and 820℃,complete decomposition of CaCO3 can be achieved in three Ca-Cu looping systems,while the operation condition of 1×10^5 Pa,840℃is required for the conventional Ca looping system.Furthermore,the Cu/Ca molar ratio of 5.13-5.19 is required for the Ca-Cu looping.Exergy analyses show that the maximum exergy destruction occurs in the calciner for the four modes and the second Ca-Cu looping system(i.e.,carbonation-oxidation-calcination/reduction)performs the highest exergy efficiency,up to 65.04%,which is about 30%higher than that of the conventional Ca looping.
基金supported by a Grant-in-Aid for Scientific Research(C)(Grant No.15K05583)from the Japan Society for the Promotion of Science
文摘Capacity and kinetics of CO_2 capture of Na_2CO_3 were studied to determine the mechanism for CO_2 sequestration under ambient conditions. Bicarbonate formation of Na_2CO_3 was examined by a thermogravimetric analysis(TGA) under various CO_2 and water vapor concentrations and the accompanying structural changes of Na_2CO_3 were demonstrated by X-ray diffraction(XRD). Morphological variations were observed during the reaction of CO_2 capture through scanning electron microscope(SEM). Structural changes and morphological variations, which occurred during the course of the reaction, were then connected to the kinetic and exothermic properties of the CO_2 capture process from the XRD and SEM measurements. The results showed that the bicarbonate formation of Na_2CO_3 has two different pathways.For higher CO_2 and H_2O concentrations, the bicarbonate formation proceeded effectively. However, for lower CO_2 and H_2O concentrations, the reactions were more complicated. The formation of Na_2CO_3·H_2O from Na_2CO_3 as the first step, followed by the subsequent formation of Na_5H_3(CO_3)_4, and then the bicarbonate formation proceeds. To understand such fundamental properties in CO_2 capture of Na_2CO_3 is very important for utilization of Na_2CO_3 as a sorbent for CO_2 capture.
文摘Due to a lack of technology,smaller breweries simply dump excess CO2 into the atmosphere,fueling the greenhouse effect and global warming.State-of-the-art CO2 capture technologies using nanofibrillated cellulose are expensive and require laborious freeze-drying.Consequently,there is a high demand for affordable alternatives in order to reduce the environmental impact in this industry sector.This work describes a novel route for a quick and cost-efficient synthesis of amine-functionalized cellulose pellets by a surfactantassisted steam explosion process.Typical values with this method were porosity of 92%and density of 67 g/cm^3.Investigations on polyethylenimine(PEI)content and distribution revealed a maximum PEI concentration of 20 wt%with decreasing concentration to the core of a pellet.Sufficient stability against brewery exhaust gas was determined and CO2 release at^120℃ could be confirmed.Capacity tests under simulated working conditions with a novel laboratory reactor yielded a CO2 capacity of 1.0 mmol/g or 67 mol/m^3,which is comparable to values known from the literature for other cellulose-based adsorbents.
基金financial support received from Ministry of Education, Universities and Research (Italy) through the RITMARE Project-SP1_WP2_A5.2 (Research National Program 2012–2016)
文摘Sorbents for CO_2 capture have been prepared by wet impregnation of a commercial active carbon(Ketjen-black, Akzo Nobel) with two CO_2-philic compounds, polyethylenimine(PEI)and tetraethylenepentamine(TEPA), respectively. The effects of amine amount(from 10 to70 wt.%), CO_2 concentration in the feed, sorption temperature and gas hourly space velocity on the CO_2 capture performance have been investigated. The sorption capacity has been evaluated using the breakthrough method, with a fixed bed reactor equipped with on line gas chromatograph. The samples have been characterized by N_2 adsorption–desorption,scanning electron microscopy and energy dispersive X-ray(SEM/EDX). A promising CO_2 sorption capacity of 6.90 mmol/gsorbenthas been obtained with 70 wt.% of supported TEPA at 70℃ under a stream containing 80 vol% of CO_2. Sorption tests, carried out with simulated biogas compositions(CH_4/CO_2mixtures), have revealed an appreciable CO_2 separation selectivity; stable performance was maintained for 20 adsorption–desorption cycles.
基金supported by the National Key Research and Development Program of China (No.2016YFB0701100)the National Natural Science Foundation of China (Nos.21622102 and 21621001)+1 种基金the National 111 Project (No.B17020)Program for JLUSTIRT,and High Performance Computing Center of Jilin University
文摘To find potential zeolitic imidazolate frameworks(ZIFs)for CO2 capture from flue gas,we built 169,898 ZIF models from 84,949 hypothetical zeolite networks.By calculating their lattice energies,accessible volumes to CO2,the isosteric adsorption heat(Qst)of H2 O,Henry’s constant ratio(SKH)of CO2/N2,percent regenerability(R%),CO2 working capacity(ΔNCO2),CO2/N2 adsorption selectivity(SCO2/N2))and adsorbent performance score(APS),we identi fied 49 hydrophobic ZIF structures that might outplay already-realised ZIFs built from the same imidazolate linkers for CO2 capture from flue gas.
基金supported by the Fundamental Research Funds for the Central Universities (2016ZCQ03)Beijing Excellent Young Scholar (2015000026833ZK11)+1 种基金the National Natural Science Foundation of China (51622801,51572029,and 51308045)the Xu Guangqi Grant
文摘Herein we report a systematical investigation on the promoting effect of the carbon chain length of the intercalated carboxylic anions on the CO_2 capture performance of Mg-Al layer double hydroxides(LDHs).A series of organo-LDHs were successfully synthesized via co-precipitation and calcination-rehydration methods. All as-prepared samples were characterized by many techniques including XRD, ATR-FTIR, BET,and TGA. The XRD and ATR-FTIR studies indicated that organic anions were successfully intercalated into LDHs. The influence of some important parameters such as calcination temperature, adsorption temperature, and coating with(Li-Na-K)NO_3 molten salt was investigated. The results exhibited that when the number of carbon is greater than 10, the CO_2 capture capacity steadily increased with the increase in carbon number. After coating with 55 mol%(Li-Na-K)NO_3 molten salt, the CO_2 uptake of LDH-C16 sample with high Mg/Al ratios can be increased up to 3.25 mmol/g. The CO_2 adsorption/desorption cycling stability was also studied using temperature swing adsorption, which showed a stable CO_2 capture performance even after 22 cycles. Considering its high CO_2 capture capacity and good cycling stability, this novel CO_2 adsorbent is very promising in the sorption-enhanced water gas shift(SEWGS) processes.
基金supported financially by the National Natural Science Foundation of China (No. 21607121)by the National Research Foundation of Korea (NRF) (Grant number: NRF2015R1A4A1042434)
文摘Amine-silica composite materials for post-combustion CO_2 capture have attracted considerable attention because of their high CO_2 uptake at low CO_2 concentrations, excellent CO_2 capture selectivity in the presence of moisture, and lower energy requirements for sorbent regeneration. This review discusses the recent advances in amine-silica composites for CO_2 capture, including adsorbent preparation and characterization, CO_2 capture under dry and moisture conditions at different CO_2 partial pressures, sorbent regeneration, and stability after many cyclic sorption-desorption runs.
基金the financial supports by the Natural Science Foundation of China (NSFC21576158, 21476132, 21576159 and 21403130)Shandong Provincial Natural Science Foundation, China (No. 2015 ZRB01765)
文摘Porous carbon spheres are prepared by direct carbonization of potassium salt of resorcinol-formaldehyde resin spheres, and are investigated as CO_2 adsorbents. It is found that the prepared carbon materials still maintain the typical spherical shapes after the activation, and have highly developed ultra-microporosity with uniform pore size, indicating that almost the activation takes place in the interior of the polymer spheres. The narrow-distributed ultra-micropores are attributed to the "in-situ homogeneous activation"effect produced by the mono-dispersed potassium ions as a form of -OK groups in the bulk of polymer spheres. The CS-1 sample prepared under a KOH/resins weight ratio of 1 shows a very high CO_2 capture capacity of 4.83 mmol/g and good CO_2/N_2 selectivity of ~17-45. We believe that the presence of a welldeveloped ultra-microporosity is responsible for excellent CO_2 sorption performance at room temperature and ambient pressure.
基金partly supported by the Research Council of Norway through CLIMIT program (MCIL-CO_2 project, 215732)
文摘A membrane contactor using ionic liquids(ILs) as solvent for pre-combustion capture CO_2 at elevated temperature(303-393 K) and pressure(20 bar) has been studied using mathematic model in the present work. A comprehensive two-dimensional(2 D) mass-transfer model was developed based on finite element method. The effects of liquid properties, membrane configurations, as well as operation parameters on the CO_2 removal efficiency were systematically studied. The simulation results show that CO_2 can be effectively removed in this process. In addition, it is found that the liquid phase mass transfer dominated the overall mass transfer. Membranes with high porosity and small thickness could apparently reduce the membrane resistance and thus increase the separation efficiency. On the other hand, the membrane diameter and membrane length have a relatively small influence on separation performance within the operation range.
基金financially supported by the Zhejiang Provincial Natural Science Foundation of China(LY16B060014)State Key Laboratory of Chemical Engineering(No.SKL-ChE-08A01)the Innovation and Development of Marine Economy Demonstration。
文摘Using the ionic liquid[emim][Tf2N]as a physical solvent,it was found by Aspen Plus simulation that it was possible to attempt to capture CO2 from the flue gas discharged from the coal-fired unit of the power plant.Using the combination of model calculation and experimental determination,the density,isostatic heat capacity,viscosity,vapor pressure,thermal conductivity,surface tension and solubility of[emim][Tf2N]were obtained.Based on the NRTL model,the Henry coefficient and NRTL binary interaction parameters of CO2 dissolved in[emim][Tf2N]were obtained by correlating[emim][Tf2N]with the gas–liquid equilibrium data of CO2.Firstly,the calculated relevant data is imported into Aspen Plus,and the whole process model of the ionic liquid absorption process is established.Then the absorption process is optimized according to the temperature distribution in the absorption tower to obtain a new absorption process.Finally,the density,constant pressure heat capacity,surface tension,thermal conductivity,and viscosity of[emim][Tf2N]were changed to investigate the effect of ionic liquid properties on process energy consumption,solvent circulation and heat exchanger design.The results showed that based on the composition of the inlet gas stream to the absorbers,CO2 with a capture rate of 90%and a mass purity higher than 99.5%was captured.These results indicate that the[emim][Tf2N]could be used as a physical solvent for CO2 capture from coal-fired units.In addition,the results will provide a theoretical basis for the design of new ionic liquids for CO2 capture.
基金Sponsored by the Hebei Natural Science Foundation of Hebei Province of China(Grant No.B2014502056)
文摘In order to study the effects of nanoparticles on the CO_2 absorption in ammonia,nanofluids with different ammonia concentration and different nanoparticle solid loading were prepared by a two-step method.The nanofluids-enhanced gas absorption test devices were also established. The CO_2 absorption in TiO_2,CuO,SiO_2 nanofluids,which nanoparticles solid loading were 1. 0-8. 0 g/L,was tested respectively. In comparison with the blank absorption experiment,the effects of nanoparticle solid loading,nanoparticle types,ammonia concentration on the removal efficiency and removal rate were obtained. Experimental results show that adding nanoparticles can enhance the removal efficiency and removal rate,which increase first and then decrease with the increase of nanoparticle solid loading,and there exists an optimum solid loading of TiO_2 nanoparticles. The effect of SiO_2 nanofluid is inhibitory on the reaction. The enhancement factor of CuO nanofluid is always hovering around 1,which does not show the obvious enhancement or inhibition on the reaction. The optimum solid loading decreases gradually with the increase of ammonia concentration. In addition,according to the experimental results,the mechanism of enhanced absorption was analyzed theoretically.
基金supported by the Natural Science Foundation of China (Nos.21706106,21536001 and 21322603)the National Key Basic Research Program of China ("973") (No.2013CB733503)+1 种基金the Natural Science Foundation of Jiangsu Normal University(16XLR011)Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘The globally increasing concentrations of greenhouse gases in atmosphere after combustion of coal-or petroleum-based fuels give rise to tremendous interest in searching for porous materials to efficiently capture carbon dioxide(CO_2) and store methane(CH4), where the latter is a kind of clean energy source with abundant reserves and lower CO_2 emission. Hundreds of thousands of porous materials can be enrolled on the candidate list, but how to quickly identify the really promising ones, or even evolve materials(namely, rational design high-performing candidates) based on the large database of present porous materials? In this context, high-throughput computational techniques, which have emerged in the past few years as powerful tools, make the targets of fast evaluation of adsorbents and evolving materials for CO_2 capture and CH_4 storage feasible. This review provides an overview of the recent computational efforts on such related topics and discusses the further development in this field.
文摘Although not everybody wants to admit,climate change has been happening with irreversible consequences.It is getting worse and worse and becoming more and more influential to not only the environment but also to all kinds of beings;our earth is now seriously threatened by climate change.It is a critical issue the whole society must face and actions must
基金sponsored by the National Science Foundation(CMMI-1562907)the financial support from the National Natural Science Foundation of China(51678511 and 51308484)+4 种基金the Open Fund of Key Laboratory of Mineralogy and Metallogeny in Chinese Academy of Sciences(KLMM20150104)the Natural Science Foundation of Hunan Province(13JJ4049)the Education Department Fund of Hunan Province(14C1094)the Major Talent Training Program of Xiangtan University(16PYZ09)the Specialized Research Fund for the Doctoral Program of Xiangtan University(12QDZ18)
文摘Hybrid adsorbents for CO_2 capture were prepared by coassembling laponite(LP) nanosheets and 1-nbutyl-3-methylimidazolium chloride(BMIMCl). The prepared BMIMCl/LP layered hybrids were systematically characterized. The interlayer distance of the BMIMCl/LP layered hybrids expanded with an increasing concentration of BMIMCl, indicating that cumulative BMIMCl was intercalated into the LP layers. The efficiency of BMIMCl toward CO_2 capture was significantly enhanced after it was immobilized within LP layers.
基金the financial support provided by the Ministry of Higher Education&Scientific Research of Iraq。
文摘A mechanistic model is developed to investigate the influence of an activator on the corrosion rate of carbon steel in the absorption processes of carbon dioxide(CO2).Piperazine(PZ)is used as the activator in diethanolamine(DEA)aqueous solutions.The developed model for corrosion takes into consideration the effect of fluid flow,transfer of charge and diffusion of oxidizing agents and operating parameters like temperature,activator concentration,CO2 loading and pH.The study consists of two major models:Vapor–liquid Equilibrium(VLE)model and electrochemical corrosion model.The electrolyte-NRTL equilibrium model was used for determination of concentration of chemical species in the bulk solution.The results of speciation were subsequently used for producing polarization curves and predicting the rate of corrosion occurring at the surface of metal.An increase in concentration of activator,increases the rate of corrosion of carbon steel in mixtures of activated DEA.
基金financially supported by the projects PAPIITUNAM(IN-101916)CONACyTDGAPA-UNAM for financial support
文摘In this work, CaO-NiO mixed oxide powders were evaluated as consecutive CO_2 chemisorbents and catalytic materials for hydrogen production thought the CH_4 reforming process. Between the NiO impregnated CaO and CaO-NiO mechanical composite, the first one presented better chemical behaviors during the CO_2 capture and CH_4 reforming processes, obtaining syngas(H_2+ CO) as final product. Results showed that syngas was produced at two different temperature ranges, between 400 and 600 °C and at T > 800 °C, where the first temperature range corresponds to the CH_4 reforming process but the second temperature range was attributed to a different catalytic reaction process: CH_4 partial oxidation. These results were confirmed through different isothermal and cyclic experiments as well as by XRD analysis of the final catalytic products, where the nickel reduction was evidenced. Moreover, when a CO-O_2 flow was used during the carbonation process a triple process was achieved:(i) CO oxidation,(ii) CO_2 chemisorption and(iii) CH_4 reforming. Using this gas flow the hydrogen production was always higher than that obtained with CO_2.
基金financially supported by the projects PAPIITUNAM(IN-101916)SENER-CONACYT(251801)+1 种基金CONACYTDGAPA-UNAM for financial support
文摘The effect of CO_2 partial pressure was evaluated during the CO_2 chemisorption in penta lithium aluminate(Li_5AlO_4), using different CO_2 and O_2 partial pressures in the presence or absence of alkaline carbonates. Results showed that using low PO_2(0.1) did not affect the kinetic and final CO_2 chemisorption process. Moreover, small additions of oxygen(PO_2= 0.05) into the mixture flue gas, seemed to increase the CO_2 chemisorption. Additionally, the presence of alkaline carbonates modified the CO_2 capture temperature range. CO_2 chemisorption kinetic parameters were determined assuming a double exponential model where direct CO_2 chemisorption and CO_2 chemisorption controlled by diffusion processes are considered.Finally, ionic diffusion was analyzed by ionic conduction analysis, where all the gravimetric and ionic measurements were in good agreement showing different diffusion processes depending on temperature.Finally, the oxygen and alkaline carbonate additions have positive effects during the CO_2 chemisorption process in Li_5AlO_4, and a possible reaction mechanism is presented.