Amino functionalized mesostructured SBA-15 silica for CO2 capture: Exploring the relation between the adsorption capacity and the distribution of amino groups by TEM

Abstract

The distribution of amino groups on amino-functionalized SBA-15 materials for CO 2 adsorption was studied by Transmission Electron Microscopy (TEM) in combination with a staining technique using RuO 4 in order to analyse the influence of the aminated organic chains location on the CO 2 adsorption properties. Mesostructured aminofunctionalized SBA-15 materials were obtained by co-condensation, grafting and impregnation using aminopropyl, AP (N), ethylene-diamine, ED (NN), diethylenetriamine, DT (NNN) and polyethyleneimine, PEI, as functionalizing agents. CO 2 adsorption isotherms of functionalized samples at 45 ºC showed that both the adsorption capacity (mg CO 2 /g ads) and the efficiency of amino groups (mol CO 2 /mol N) depend on the functionalization technique and the amount of organic compound used. While samples synthesized by co-condensation showed negligible CO 2 uptake and efficiency, adsorbents prepared by grafting and impregnation presented significant CO 2 adsorption capacities but a dissimilar efficiency. Key differences in the location of aminated chains explained the performance of CO 2 capture for every adsorbent, being grafted samples the adsorbents where amino groups were better distributed, favouring the CO 2 diffusion trough the whole structure.

Dummy molecularly imprinted mesoporous silicates for selective adsorption of 2-naphthol

“…3-Isocyanatopropyltriethoxysilane (IPTES), (3-aminopropyl)triethoxysilane (APTES) and Pluronic P123 (EO 20 PO 70 EO 20 , MW = 5800 Da) were purchased from Sigma Chemical Co., St. Louis. All other chemicals used were of analytical grade.…”

“…Since a pre-hydrolysis process was used for synthesis of NIMS, in which AP groups were distributed both in the pore channels (minor) and inside the walls of the resulting materials [20], MIMS-1, prepared by 2-naphthol (1) as template, incorporated similar amount of AP groups (calculated by the molar ratio of TEOS/1-Si) with did in NIMS (calculated by TEOS/APTES). By comparison of the adsorption behavior of MIMS-1 and NIMS, the location of AP groups in the materials could be distinguished.…”

ADSORPTION OF CO2ON MICRO AND MESOPOROUS MOLECULAR SIEVES

“…Peneiras moleculares baseadas em rede de sílica micro e mesoporosas, carvões ativos, hidrotalcitas, redes organometálicas (MOFs) e aminas interagindo com diferentes óxidos constituem as principais classes de adsorventes estudados para aplicação na adsorção de CO 2 . [3][4][5][8][9][10][11][12][13][14] As características superficiais e estruturais destes materiais são as mais variadas possíveis e o entendimento da interação do CO 2 com estes materiais ainda precisam ser mais bem estudados.…”

“…Peneiras moleculares baseadas em rede de sílica micro e mesoporosas, carvões ativos, hidrotalcitas, redes organometálicas (MOFs) e aminas interagindo com diferentes óxidos constituem as principais classes de adsorventes estudados para aplicação na adsorção de CO 2 . [3][4][5][8][9][10][11][12][13][14] As características superficiais e estruturais destes materiais são as mais variadas possíveis e o entendimento da interação do CO 2 com estes materiais ainda precisam ser mais bem estudados.Dentre os materiais microporosos pode-se destacar que as zeólitas compreendem o maior grupo das peneiras moleculares microporosas e são intensamente usadas para a separação e purificação de gases, troca iônica, adsorção e catálise. 4,[15][16][17][18][19][20][21][22][23] A eficiência das zeólitas nestes processos se deve a algumas de suas características, tais como: forte acidez/basicidade, estabilidade térmica e hidrotérmica, seletividade e capacidade de adsorção de muitos adsorbatos, etc.…”

Amine impregnated porous silica gel sorbents synthesized from water–glass precursors for CO2 capturing

“…Carbon materials like graphene, zeolites, metal organic frameworks and alkali metal carbonates are also fastly emerging as potential CO 2 adsorbents [8][9][10]. A large number of porous materials like MCM-41, SBA-15, porous silica, clays etc have been reported in the literature; CO 2 adsorption on such porous materials is usually governed by physical adsorption and therefore capacity and selectivity values are generally poor at elevated temperatures [11][12][13][14][15]. Recently, such porous materials grafted with amine functionality or impregnated with amine containing molecules are also reported and found to exhibit better selectivity, and increased CO 2 adsorption capacity.…”