Membrane separation technology has popularized rapidly and attracts much interest in gas industry as a promising sort of newly chemical separation unit operation. In this paper, recent advances on membrane processes f...Membrane separation technology has popularized rapidly and attracts much interest in gas industry as a promising sort of newly chemical separation unit operation. In this paper, recent advances on membrane processes for CO_2 separation are reviewed. The researches indicate that the optimization of operating process designs could improve the separation performance, reduce the energy consumption and decrease the cost of membrane separation systems. With the improvement of membrane materials recently,membrane processes are beginning to be competitive enough for CO_2 separation, especially for postcombustion CO_2 capture, biogas upgrading and natural gas carbon dioxide removal, compared with the traditional separation methods. We summarize the needs and most promising research directions for membrane processes for CO_2 separation in current and future membrane applications. As the time goes by, novel membrane materials developed according to the requirement proposed by process optimization with increased selectivity and/or permeance will accelerate the industrialization of membrane process in the near future. Based on the data collected in a pilot scale test, more effort could be made on the optimization of membrane separation processes. This work would open up a new horizon for CO_2 separation/Capture on Carbon Capture Utilization and Storage(CCUS).展开更多
Membrane gas separation is one of the most promising technologies for the separation of carbon dioxide （CO2） from various gas streams. One application of this technology is the treatment of flue gases from combustio...Membrane gas separation is one of the most promising technologies for the separation of carbon dioxide （CO2） from various gas streams. One application of this technology is the treatment of flue gases from combustion processes for the purpose of carbon capture and storage. For this application, poly（ethylene oxide）-containing block copolymers such as Pebax or PolyActiveTM polymer are well suited. The thin-film composite membrane that is considered in this overview employs PolyActiveTM polymer as a selective layer material. The membrane shows excellent CO2 permeances of up to 4 m^3（STP）.（m^2·h·bar）^-1 （1 bar = 105 Pa） at a carbon dioxide/nitrogen （CO2/N2） selectivity exceeding 55 at ambient temperature. The membrane can be manufactured reproducibly on a pilot scale and mounted into fiat-sheet membrane modules of different designs. The operating performance of these modules can be accurately predicted by specifically developed simulation tools, which employ single-gas permeation data as the only experimental input. The performance of membranes and modules was investigated in different pilot plant studies, in which flue gas and biogas were used as the feed gas streams. The investigated processes showed a stable separation performance, indicating the applicability of PolyActiveTM polymer as a membrane material for industrialscale gas processing.展开更多
The adsorption method based on solid adsorbents is one of feasible ways to capture and store CO2. Using the ion exchange method, different zeolites Na KA varying in K＋content were produced. The adsorption isotherms a...The adsorption method based on solid adsorbents is one of feasible ways to capture and store CO2. Using the ion exchange method, different zeolites Na KA varying in K＋content were produced. The adsorption isotherms and kinetic uptakes were measured. The experimental results show that the optimal NaKA could adsorb significant quantities of CO2 and little N2. On the zeolite Na KA with 14.7 at.% K＋, the adsorption capacity for pure CO2 is over 3.10 mmol g^-1 and the CO2–N2 selectivity is about 149 at ambient pressure and temperature. The kinetic CO2–N2 selectivity could also achieved 200 within 3 min according to the uptake data. To demonstrate the separation effectiveness, breakthrough curves of pure components and binary mixtures were investigated experimentally and theoretically in a fixed bed. It is found that the breakthrough points of CO2 and N2 are almost at the same time under the atmospheric pressure at 348 K with the raw gas composition CO2/N2（20：80, v/v）. If the pressure has been increased higher than 0.1 MPa, CO2 would break through the bed much slower than N2. Therefore, the pressure may become the limiting factor for the separation performance of zeolites NaKA.展开更多
CaSO4 is an attractive oxygen carrier for chemical looping combustion（CLC） because of its high oxygen capacity and low price. The utilization of a CaSO4 oxygen cartier suffers the problems of sulfur release, and dea...CaSO4 is an attractive oxygen carrier for chemical looping combustion（CLC） because of its high oxygen capacity and low price. The utilization of a CaSO4 oxygen cartier suffers the problems of sulfur release, and deacti- vation caused by sulfur loss. With respect to the fact that partial sulfur release could be recaptured and then recycled to CaSO4 by CaO sorbent, the mixture of CaSO4-CaO can be treated as an oxygen carrier. Thermodynamics of CaSO4 and CaSO4-CaO reduction by CO have been investigated in this study. The sulfur migrations, including the sulfur migration from CaSO4 to gas phase, mutual transformation of sulfur-derived gases and sulfur migration from gas phase to solid phase, were focused and elucidated. The results show that the releases of S2, S8, COS and CS2 from CaSO4 oxygen carrier are spontaneous, while SO2 can be released at high reaction temperatures above 884 ℃. SO2 is the major emission source of sulfur at low CO/CaSO4 molar ratios, and COS is the major part of the byproducts as soon as the ratio exceeds 4 at 900℃. Under CO atmosphere, all the sulfur-derived gases, SO2, S2, S8 and CS2, involved are thermodynamically favored to be converted into COS substance, and are spontaneously absorbed and solidified by CaO additive just into CaS species, which may be recycled to CaSO4 as oxygen carrier in the air reactor. But high reaction temperatures and high CO2 concentrations are adverse to sulfur capture.展开更多
基金Supported by the National Key R&D Program of China(No.2017YFB0603400)the National Natural Science Foundation of China(No.21436009)Tianjin Research Program of Basic Research and Frontier Technology(No.15JCQNJC43400)
文摘Membrane separation technology has popularized rapidly and attracts much interest in gas industry as a promising sort of newly chemical separation unit operation. In this paper, recent advances on membrane processes for CO_2 separation are reviewed. The researches indicate that the optimization of operating process designs could improve the separation performance, reduce the energy consumption and decrease the cost of membrane separation systems. With the improvement of membrane materials recently,membrane processes are beginning to be competitive enough for CO_2 separation, especially for postcombustion CO_2 capture, biogas upgrading and natural gas carbon dioxide removal, compared with the traditional separation methods. We summarize the needs and most promising research directions for membrane processes for CO_2 separation in current and future membrane applications. As the time goes by, novel membrane materials developed according to the requirement proposed by process optimization with increased selectivity and/or permeance will accelerate the industrialization of membrane process in the near future. Based on the data collected in a pilot scale test, more effort could be made on the optimization of membrane separation processes. This work would open up a new horizon for CO_2 separation/Capture on Carbon Capture Utilization and Storage(CCUS).
基金funded by the Helmholtz Association of German Research Centersthe funding given by the German Federal Ministry for Economic Affairs and Energy to finance the research project METPORE Ⅱ (03ET2016)+2 种基金the METPORE Ⅱ project partnersSSC Strategic Science Consult GmbHBORSIG Membrane Technology GmbH
文摘Membrane gas separation is one of the most promising technologies for the separation of carbon dioxide （CO2） from various gas streams. One application of this technology is the treatment of flue gases from combustion processes for the purpose of carbon capture and storage. For this application, poly（ethylene oxide）-containing block copolymers such as Pebax or PolyActiveTM polymer are well suited. The thin-film composite membrane that is considered in this overview employs PolyActiveTM polymer as a selective layer material. The membrane shows excellent CO2 permeances of up to 4 m^3（STP）.（m^2·h·bar）^-1 （1 bar = 105 Pa） at a carbon dioxide/nitrogen （CO2/N2） selectivity exceeding 55 at ambient temperature. The membrane can be manufactured reproducibly on a pilot scale and mounted into fiat-sheet membrane modules of different designs. The operating performance of these modules can be accurately predicted by specifically developed simulation tools, which employ single-gas permeation data as the only experimental input. The performance of membranes and modules was investigated in different pilot plant studies, in which flue gas and biogas were used as the feed gas streams. The investigated processes showed a stable separation performance, indicating the applicability of PolyActiveTM polymer as a membrane material for industrialscale gas processing.
文摘The adsorption method based on solid adsorbents is one of feasible ways to capture and store CO2. Using the ion exchange method, different zeolites Na KA varying in K＋content were produced. The adsorption isotherms and kinetic uptakes were measured. The experimental results show that the optimal NaKA could adsorb significant quantities of CO2 and little N2. On the zeolite Na KA with 14.7 at.% K＋, the adsorption capacity for pure CO2 is over 3.10 mmol g^-1 and the CO2–N2 selectivity is about 149 at ambient pressure and temperature. The kinetic CO2–N2 selectivity could also achieved 200 within 3 min according to the uptake data. To demonstrate the separation effectiveness, breakthrough curves of pure components and binary mixtures were investigated experimentally and theoretically in a fixed bed. It is found that the breakthrough points of CO2 and N2 are almost at the same time under the atmospheric pressure at 348 K with the raw gas composition CO2/N2（20：80, v/v）. If the pressure has been increased higher than 0.1 MPa, CO2 would break through the bed much slower than N2. Therefore, the pressure may become the limiting factor for the separation performance of zeolites NaKA.
基金Supported by the National Natural Science Foundation of China（Nos.51306084, 51374004）, the Scientific and Technological Leading Talent Projects in Yuunan Province, China（No.2015HA019） and the Natural Science Foundation of Kunming University of Science and Technology, China（No.KKZ3201352030）.
文摘CaSO4 is an attractive oxygen carrier for chemical looping combustion（CLC） because of its high oxygen capacity and low price. The utilization of a CaSO4 oxygen cartier suffers the problems of sulfur release, and deacti- vation caused by sulfur loss. With respect to the fact that partial sulfur release could be recaptured and then recycled to CaSO4 by CaO sorbent, the mixture of CaSO4-CaO can be treated as an oxygen carrier. Thermodynamics of CaSO4 and CaSO4-CaO reduction by CO have been investigated in this study. The sulfur migrations, including the sulfur migration from CaSO4 to gas phase, mutual transformation of sulfur-derived gases and sulfur migration from gas phase to solid phase, were focused and elucidated. The results show that the releases of S2, S8, COS and CS2 from CaSO4 oxygen carrier are spontaneous, while SO2 can be released at high reaction temperatures above 884 ℃. SO2 is the major emission source of sulfur at low CO/CaSO4 molar ratios, and COS is the major part of the byproducts as soon as the ratio exceeds 4 at 900℃. Under CO atmosphere, all the sulfur-derived gases, SO2, S2, S8 and CS2, involved are thermodynamically favored to be converted into COS substance, and are spontaneously absorbed and solidified by CaO additive just into CaS species, which may be recycled to CaSO4 as oxygen carrier in the air reactor. But high reaction temperatures and high CO2 concentrations are adverse to sulfur capture.
