Effects of different structure-directing agents (SDA) in MCM-41 on the adsorption of CO2

• Published in: Journal of porous materials 2014-12, Vol.21 (6), p.1069-1077
• Main Authors: Costa, C. C., Melo, D. M. A., Melo, M. A. F., Mendoza, M. E., Nascimento, J. C., Andrade, J. M., Barros, J. M. F.
• Format: Article
• Language: English
• Subjects: Catalysis; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Physical Chemistry
• ISSN: 1380-2224; 1573-4854
• DOI: 10.1007/s10934-014-9857-9

CO 2 capturing technologies have attracted significant attention in order to limit emissions and reduce their negative effect on the environment. Mesoporous silica materials (MCM-41) are easily recyclable, affordable, and thermally and mechanically stable, providing added benefits in CO 2 capture. However, further studies are necessary to characterize the effects of MCM-41 pore size, adsorption temperature and surface silylation on CO 2 adsorption efficiency. In this work, mesoporous silica is synthesized using alkyltrimethylammonium bromide with different chain lengths (C n H 2n  + 1 N(CH 3 ) 3 Br, n = 14, 16 and 18) as structure-directing agents, and the adsorption capacity of CO 2 on TTMCM-41 (C 17 H 38 NBr), CTMCM-41 (C 19 H 42 NBr), DTMCM-41(C 21 H 46 NBr) samples was measured gravimetrically at room temperature and pressure up to 40 bar. The silica structures were characterized by X-ray diffraction (XRD), nitrogen adsorption/desorption, Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy (TEM). The XRD, N 2 adsorption–desorption and TEM measurements indicated the presence of a well-ordered hexagonal array with uniform mesostructures. The mesoporous silica obtained, denoted as TTMCM-41, CTMCM-41 and DTMCM-41, had distinct physical properties, such as BET surface area, hexagonal unit cell, pore volume, pore diameter and pore wall thickness. CTMCM-41 exhibited an adsorption capacity (0.58 g CO 2 /g adsorbent) of more than DTMCM-41 (0.48 g CO 2 /g adsorbent) and TTMCM-41 (0.42 g CO 2 /g adsorbent). The results suggest that CTMCM-41 can be a better mesoporous adsorbent for CO 2 adsorption .