复合氨基改性Mg-Al LDH的制备及其CO2吸附性能的研究

Synthesis of Amine Modified Mg-Al LDH and their CO_2 Adsorption Characteristics

研究提出了一种层状双氢氧化物(LDHs)复合改性方法,分别以3-氨丙基三甲氧基硅烷(N1)和N-氨乙基-γ-氨丙基三甲氧基硅烷(N2)为改性剂,制备了一系列Mg-Al LDH,采用XRD、FT-IR、EA和TG等手段对制备的材料进行表征,考察氨基负载量对LDHs CO_2吸附性能的影响规律,优选出吸附性能优良的氨基改性LDHs,考察吸附温度等对其吸附性能的影响,并研究了其循环再生性能。结果表明,复合改性法克服了剥落法和阴离子表面活性剂法等常用的氨基改性方法难以进一步提高LDHs氨基负载量的不足,得到了具有较高氨基负载量的LDHs;Mg-Al LDH的CO_2吸附容量随氨基负载量的增大而增大,氨基负载量为6.20 mmol×g^(-1),在30℃、0.1 MPa纯CO_2环境下Mg-Al N2吸附容量高达2.26 mmol×g^(-1);在考察温度30~90℃,温度越高,吸附容量越小;Mg-Al N2在140℃下脱附完全,循环使用5次后,其结构与性能基本不变。

A series of amine modified layered double hydroxides（LDHs） were prepared using 3-aminopropyltrimethoxysilane（N1） and N-aminoethyl-γ-aminopropyltrimethoxysilane（N2） as grafting agents,and these LDHs were characterized by X-ray diffraction（XRD）, Flourier Transform Infrared spectroscopy（FT-IR）, elemental analysis（EA） and thermogravimetric analysis（TG）. Effects of amine loading on CO_2 adsorption were investigated and the amine modified LDH with excellent adsorption performance was selected.Effects of adsorption temperature on adsorption and recycling performance were further investigated. The results indicate that the composite amine modification method overcomes the shortcoming of conventional amine modified methods such as exfoliation and anionic surfactant methods which are difficult to further improve amine loading. LDH with high amine loading was obtained. CO_2 adsorption increases with the increase of amine loading. Mg-Al N2 with amine loading of 6.20 mmol×g^（-1） has an adsorption capacity of 2.26 mmol×g^（-1） at 30℃ and 0.1 MPa. CO_2 adsorption capacity reduces when temperature increases from 30℃ to 90℃. Moreover, CO_2 can be completely desorbed at 140℃ and the structure and performance of the adsorbent remains unchanged after five adsorption-desorption cycles.