Practical and Theoretical Study of the Adsorption Performances of Straw-Based Tertiary Amine-Supported Material toward Sulfur Dioxide in Flue Gas

Liming Sun, Xiaofan Zhu

Abstract


The primary and secondary amines of tetraethylenepentamine (TEPA) were N-methylated into tertiary amines through the Eschweiler-Clarke reaction. A straw-based tertiary amine-supported material (STA) was developed for SO2 removal, using a wet impregnation process. The effect of the adsorption conditions, such as the moisture content, flow rate, and adsorption temperature, as well as the regeneration performances were studied. Experimental results showed that STA has high SO2 adsorption capacity (approximately 100 mg/g) and can be regenerated at 100 °C. Furthermore, the adsorption of SO2 molecules on tertiary amine was studied using density functional theory (DFT). The most stable geometries of the adsorption structure in five possible positions, the geometric changes after the adsorption, and the corresponding adsorption energies were analyzed. The results showed that modified TEPA (M-TEPA) has four potential adsorbed sites (N(1,3,4,5)) with a small adsorption energy, indicating that the adsorption is weak. Moreover, the energy of the adsorbed SO2 on the N(1,3,4,5) is less than zero, indicating that the adsorption process is exothermic and spontaneous. The theoretical investigation agreed well with the experimental results.

Keywords


Straw; Density functional theory; Amine-supported material; Sulfur dioxide; Adsorption

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