Single site Ni(II) anchored tetraethylene pentamine for enhancing CO2 kinetic adsorption rate and long-term cyclic stability

Abstract

Rapid kinetic adsorption and long-term cyclic stability are two of the major obstacles to the industrialization of solid amine adsorbents. The morphology and dispersibility of the organic amine in the pore structure of the support can strongly affect the adsorption rate and stability of CO2. In this work, we propose a strategy that enhances the dispersion and stability of tetraethylene pentamine (TEPA) via anchoring TEPA with single site Ni(II) in the pore of the commercial mesoporous silica gel (SG). The microscopic morphology and dynamic behavior of TEPA molecules in the adsorbents preparation process were explored by molecular dynamics simulation, which proved that the dispersibility of anchored TEPA in the porous structure has been improved, resulting in enhanced mass transfer and increased kinetic adsorption rate. The anchored Ni-TEPA/SG adsorbents exhibit a 37.5% faster kinetic adsorption rate than TEPA/SG adsorbents at 30 wt% TEPA loading, and the time required to reach 90% of maximum adsorption capacity is shortened by 6 times. Besides, the CO2 adsorption performance of the optimized Ni-TEPA/SG adsorbent remains unchanged after 20 cycles, consolidating the potential of our proposed strategy in improving the kinetic adsorption rate and cyclic stability of solid amine adsorbents as well as promoting its industrialization.