|吴晋沪 研究员 ; 杨 成 副研究员
|Place of Conferral
|二氧化碳 有机胺 介孔硅材料 动态浸渍 吸附机理
通过筛选制备方法和控制浸渍过程将TEPA负载到SBA-15(P)上制备氨基修饰的CO2吸附剂-TEPA/SBA-15(P)，系统考察了浸渍次数和浸渍液胺浓度等动态浸渍效果的影响，阐述了TEPA在SBA-15(P)上的键合作用机制。通过考察动态浸渍次数和浸渍液胺浓度对动态浸渍效果的影响表明，动态浸渍中，在每次浸渍溶液用量35 mL，停留时间20 min的情况下，浸渍4次以及浸渍溶液TEPA与EtOH体积比为1:50时最合适；动态浸渍法提高了有机胺TEPA在载体SBA-15(P)上分散度并改善了结合形态，从而提高了吸附剂的稳定性。
系统考察了TEPA改性SBA-15(P)材料的CO2吸/脱附适用的工艺条件，实验研究表明，对于浓度为9.62%的CO2适宜的吸/脱附条件为：吸附温度75 ºC，气体流速20 mL·min-1，升温速率5 ºC·min-1，吸附时间30 min，脱附温度和时间分别为100 ºC和30 min。该吸附剂对浓度为9.62%和99.999%的CO2吸附容量基本一致，无水和有水气氛对吸附材料吸附CO2的容量影响不大。
The burning of fossil fuels emits CO2, which is considered to be the main greenhouse gas causing global warming. Post-combustion capture is one of the effective ways to control large scale industrial CO2 emissions, while the preparation of novel amino-modified mesoporous molecular sieves with excellent properties for CO2 adsorption was widely focused as the key for CO2 separation.
In this work, an amino-modified mesoporous molecular sieve based adsorbent with high CO2 adsorption capacity and high stability was designed and prepared, and the relative basic theories were studied. A mechanism of binding and grafting on tetraethylenepenthamine (TEPA) incorporated onto SBA-15(P) was investigated, thus a new method of dynamic impregnation for the absorbent preparation was developed and optimized. Then, the parameters which affect the adsorption/desorption process were performed, and an efficient monolithic adsorption system was constructed. Moreover, CO2 adsorption/desorption behaviors on the surface of adsorbent were analysed by in-situ Fourier transform infared spectroscopy (in-situ FTIR), and mechanism of the process was discussed. .
Various amine-functionalized CO2 adsorbents were prepared by incorporating TEPA onto SBA-15(P) through selecting preparation and controlling impregnation process. The influencing factors, such as the impregnation times and amine concentration were systematically investigated. The mechanism of dynamic impregnation was clearly understood. The results indicate that the optimized process parameters for dynamic impregnation were of solution 35 mL, residence time 20 min, four times impregnating, and the volume ratio of amine to ethanol 0.02. Dynamic impregnation got a high TEPA dispersion state and facilitated the bonding formation between TEPA and SBA-15(P). Therefore, the stability of adsorbent was enhanced.
Influencing factors for adsorption/desorption of CO2 on TEPA/SBA-15(P) were investigated. The experimental results show that the suitable adsorption conditions for 9.62% CO2 flow were at 75 ºC, under gas flow rate of 20 mL·min-1, and the heat rate is 5 ºC·min-1 for 30 min adsorption, while 100 ºC and 30 min for desorption process. The adsorption capacities were in substantial agreement, when the adsorption was exposed to CO2 with concentration 9.62% and 99.999%, respectively. Water in stream was found little affected on the adsorption capacity.
A monolithic adsorption system was prepared by dip-coating using TEPA/SBA-15(P) as active component and honeycomb ceramic as inert support. Its cyclic adsorption capacities for CO2 were studied. The results show that monolith adsorbent retained higher adsorption capacity for CO2 compared to the particle adsorbent. With excellent mass and heat transfer properties, the particle agglomerate rate was decreased significantly for monolith adsorbent.
The adsorption mechanism of the adsorbent for CO2 was examined by in-situ FTIR technique. The main adsorption species were bidentate carbonate, monodentate bicarbonate, bidentate bicarbonate, cabamic acid, glycine and ammonium carbamate. The major specie of CO2 combined with the adsorbent surface was bidentate carbonate in anhydrous and water conditions.
A mixture of TEPA and AP solution was used to modify mesoporous materials for the preparation of CO2 adsorbents, as well as silica gel modified by TEPA through dynamic impregnation process. The results show that TEPA and AP modifying mesoporous materials can be used for the preparation of high adsorption capacity and high stability of CO2 absorbent. But the dynamic impregnation method is not suitable for the TEPA modifying industrial silicone to prepare CO2 adsorbent.
|杨永红. 基于有机胺改性介孔硅材料的CO2吸附剂及吸附机理研究[D]. 北京. 中国科学院研究生院,2012.
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