Soft-Pillared@Magadiite: influence of the interlayer space and amine type on CO2 adsorption.

Abstract

Layered silicates are versatile materials that can be grafted with different organosilanes for several applications. Despite this, there are few studies on the use of layered silicate-based materials in CO2 adsorption. In this regard, the present study describes the synthesis of organo-magadiite followed by simultaneous grafting with two organosilanes ((3-glycidyloxypropyl)trimethoxysilane (GPTS) and N1-(3-trimethoxysilylpropyl)diethylenetriamine (TMSPETA)) to prepare an adsorbent labeled Soft-Pillared@Magadiite. The adsorbents were characterized through XRD, 13C- and 29Si-NMR, TGA/DTG, and elemental analyses of carbon, hydrogen, and nitrogen (CHN). The results suggest that this adsorbent has an expanded interlayer space (3.05 nm) that is larger than the interlayer space when the layered material is grafted with the organosilanes separately, and it may display improved CO2 adsorption. The CO2 adsorption was evaluated by TGA, CO2-TPD, and DSC. Moreover, the adsorption isotherms were fitted using a pseudo-second order, a fractional order, and Avrami models. The optimum adsorption temperature of Soft-Pillared@Magadiite was 25 °C, and the adsorption capacity and efficiency were 0.36 mmol g-1 and 0.15, respectively, obtained using 5 vol% CO2 in He for 3 h. The CO2-TPD shows that the desorption of CO2 occurs below 90 °C, and from DSC, it is found that thermodynamic parameters, specifically sensible heat and heat of regeneration, are low as compared to those of aqueous MEA solution; the current technology indicates that Soft-Pillared@Magadiite has a good potential for CO2 adsorption.