摘要
燃煤烟气中CO_(2)减排刻不容缓,而传统吸附材料存在吸附性能有限、受烟气中杂质影响大等问题,本研究以聚环氧乙烷-聚环氧丙烷-聚环氧乙烷三嵌段共聚物为模板剂,Na_(2)SiO_(3)为硅源,制备硅基介孔材料SM,并在其上担载四乙烯五胺(TEPA)、聚乙烯亚胺(PEI)以及2-氨基-2-甲基-1-丙醇(AMP),获得硅基胺吸附剂,用于CO_(2)吸附实验。结果表明,硅基材料负载胺后,CO_(2)吸附性能均明显提高,且双胺吸附剂要优于单胺吸附剂。最优硅基胺吸附剂30PEI-30AMP/SM的CO_(2)吸附量达到4.30 mmol/g。TEPA和PEI含有大量伯胺基团,能与CO_(2)发生化学反应,但高黏度限制了它们在载体中的分散。AMP是具有羟基的位阻胺,可以引入额外的网络结构,提高吸附剂的热稳定性。双胺吸附剂不同种类的胺可以相互协作,共同提高CO_(2)的吸附性能。同时,燃煤烟气中的SO_(2)和水蒸气等成分也会对吸附剂的CO_(2)吸附性能产生重要影响。强酸性的SO_(2)会优先与碱性胺基反应,生成的亚硫酸盐会堵塞孔隙,增加CO_(2)的扩散阻力,严重抑制CO_(2)的吸附;水蒸气可以减少与等量CO_(2)反应的胺基数量,提高胺基团的利用效率,从而提高吸附剂的CO_(2)吸附性能;NO对CO_(2)吸附几乎没有影响。
Introduction CO_(2) generated from coal combustion is the main cause of the greenhouse effect,and it is urgent to reduce its CO_(2) emissions.CO_(2) capture is the key to Carbon Capture,Utilization and Storage(CCUS)technology.Silicon-based materials are commonly used as carriers for adsorbents,but their CO_(2) adsorption capacity is weak,and chemical reagents need to be supported.At present,there is little research on the stability of different diamine adsorbents and adsorbents in the presence of impurity gases.Therefore,it is necessary to prepare silicon-based amine adsorbents and explore their adsorption mechanism and the influence of various factors.In this paper,a variety of organic amines are loaded onto silicon-based materials,aiming to prepare various silicon-based amine adsorbents.The influence mechanism of adsorption temperature,amine types,and gas components(SO_(2),NO_(x),H_(2)O)on CO_(2) adsorption are carefully investigated.Methods Using P123 as the template agent and Na2SiO3 as the silicon source,the silicon-based mesoporous material SM was prepared.Then,tetraethylenepentamine(TEPA),polyethyleneimine(PEI)and 2-amino-2-methyl-1-propanol(AMP)were supported on SM to obtain the silicon-based amine adsorbents.CO_(2) adsorption mechanism of the silicon-based amine adsorbents was explored through pore structure analysis,infrared spectroscopy analysis and thermogravimetric analysis.CO_(2) adsorption experiments of the silicon-based amine adsorbents were carried out by using a fixed-bed analyzer and a thermogravimetric analyzer.Results and discussion Pore structure analysis shows that due to the filling of organic amines,the porosity decreases and the average pore diameter increases.Infrared analysis indicates that the modification of organic amines does not damage the silicon-based carrier skeleton.Some Si-OH groups form bonds with organic amines,and new characteristic peaks appear after loading,which proves the successful loading of organic amines.Thermogravimetric analysis reveals that the weight loss of the adsorbent occurs in two stages,and the silicon-based amine adsorbent exhibits good thermal stability.In terms of adsorption performance,the modification of organic amines enhances the CO_(2) adsorption capacity of SM.Modification with diamines is more effective,as CO_(2) reacts with amino groups to form specific products.Adsorption kinetics studies find that the adsorption of CO_(2) by SM is mainly physical adsorption,and the adsorption of the three diamine adsorbents is jointly affected by physical and chemical adsorption.Regarding the cyclic performance,after 10 cycles of 30PEI-30AMP/SM,the CO_(2) adsorption capacity can reach 95%of the initial capacity,and the synergistic effect of the mixed amines improves the regenerability of the adsorbent.As for the influence of gas components,SO_(2) reduces the CO_(2) adsorption capacity,water vapor enhances it,and NO has a relatively minor effect.Conclusions The main conclusions of this work are summarized as follows:1)A silicon-based mesoporous material was prepared by using P123 as the template and Na_(2)SiO_(3) as the silicon source.By impregnating with TEPA,PEI and AMP,nine monoamine adsorbents and three diamine adsorbents were synthesized.Among them,the CO_(2) adsorption performance of the silicon-based diamine adsorbents is better.2)The macromolecular amine PEl can significantly occupy the pore space,causing a significant decrease in the specific surface area and pore volume,and a relative increase in pore diameter.The small molecular amines like TEPA and AMP can maintain a higher porosity and specific surface area while filling the pores.The combination of diamines can effectively utilize the characteristics of different amines,and significantly improve the pore structure through intermolecular interactions and spatial arrangements.3)TEPA and PEI contain a large number of primary amine groups,which can react with CO_(2).However,their high viscosity limits their dispersion in the carrier.AMP,a steric hindrance amine with hydroxyl groups,forms an additional network structure,improving the thermal stability of the adsorbent.Different types of amines in the diamine adsorbents can cooperate with each other to enhance their CO_(2) adsorption performance.4)SO2 in coal-fired flue gas will compete with CO_(2) for the limited adsorption sites in the adsorbent,preferentially reacting chemically with the amine groups on the surface of the adsorbent,reducing the adsorption sites for CO_(2).Moreover,the generated sulfates will also block the pores,increasing the diffusion resistance of CO_(2) and resulting in a decrease in the CO_(2) adsorption performance of the adsorbent.An appropriate amount of water vapor can improve the utilization efficiency of amino groups and enhance the CO_(2) adsorption performance of the adsorbent.
作者
李冠宇
郑仙荣
宁辉
郭百合
LI Guanyu;ZHENG Xianrong;NING Hui;GUO Baihe(College of Electrical and Power Engineering,Taiyuan University of Technology,Taiyuan O30024,China)
出处
《硅酸盐学报》
北大核心
2025年第11期3382-3392,共11页
Journal of The Chinese Ceramic Society
基金
山西省自然科学研究面上项目(202303021211066)。
关键词
介孔材料
有机胺
硅基胺吸附剂
二氧化碳吸附
mesoporous material
amine
silicon-based amine adsorbents
CO_(2)adsorption
