運用擴張劑合成不同孔洞結構之中孔洞吸附材料及其應用於二氧化碳捕獲之研究

Abstract

由於現階段對影響CO2吸附量之關鍵因子，各家眾說紛紜，因此本研究目的為運用擴張劑以擴張中孔洞材料之孔徑及孔洞體積，並使其材料穩定性佳、再現性高，而後探討不同孔洞結構對CO2吸附量及胺基嫁接之影響。本研究以中孔洞Si-MCM-41為基材，運用一步合成法添加擴張劑TMB(1,3,5-Trimethylbenzene)及改變製備參數以調整孔洞大小及對應之孔洞結構，探討不同添加量與不同水熱合成時間所製成中孔洞材料的物性變化，藉此掌握相關合成比例與參數，並以製備出不同孔洞大小之吸附材進行二氧化碳吸附測試。研究結果發現，成功擴張孔洞之吸附材仍可具備高比表面積(700~800 m2/g)之特性，並將其孔徑與孔體積由3 nm、0.9 cm3/g 擴大為7~14 nm與1.6~2.3 cm3/g。而後續之二氧化碳吸附測試顯示，研究中合成之擴大孔洞吸附材於33及50 wt.%胺基改質下之吸附效能分別可達109 及125 mg CO2/g adsorbent，遠優於原先之Si-MCM-41胺基化後的70 及97 mg CO2/g adsorbent。本研究亦探討各種不同孔洞結構之中孔洞材料對CO2吸附量以及胺基嫁接分布的影響，並經由數據歸納分析出影響二氧化碳吸附量的關鍵因素為中孔洞吸附材之總孔洞體積及孔洞大小。

The structure of mesoporous support is found to play a vital role in the performance of CO2 adsorption capacity, but literature data still show no conclusion yet. The purpose of this study is to expand the pore diameter and the pore volume of the MCM-41 base material via the use of pore expander. Then, the effect of different pore structures on the CO2 adsorption capacity and amine grafting will be discussed. In this study, the mesoporous material of MCM-41 is used as the substrate, and by adding the expansion agent of TMB (1,3,5-Trimethylbenzene) and changing the preparation parameters the pore diameter and the pore structure can be adjusted. The amount of TMB and the hydrothermal synthesis time on the pore structure are evaluated. Then several pore-expanded mesoporous materials with different pore structures are synthesized and functionalized with TEPA in order to evaluate the CO2 adsorption performance of these materials. The result shows that successful expansion on the pore diameters and volumes of MCM-41 is achieved, with the pore diameter increases from 3 nm up to 14 nm, and the pore volume increases from 0.99 cm3/ g up to 2.3 cm3/ g. In the meanwhile the high surface area of around 800 m2/ g can still be maintained. Furthermore, the correlation between CO2 adsorption capacity and the pore structure properties (pore size, pore volume and specific surface area) is studied. The result of the linear regression indicates that the CO2 adsorption capacity has the strongest correlation with the total pore volume of the mesoporous materials (R2>0.9). And the optimal TEPA grafted amount on the pore-expanded MCM-41adsorbent is 50 % (wt.). It exhibits a 125 mg/g adsorption capacity, which is superior to that of the original MCM-41, 97 mg/g.