Comprehensive Study of the Impact of Steam on Polyethyleneimine on Silica for CO₂ Capture

An amine sorbent, prepared by impregnation of polyethyleneimine on silica, was tested for steam stability. The stability of the sorbent was investigated in a fixed bed reactor using multiple steam cycles of 90 vol % H 2 O/He at 105 °C, and the gas effluent was monitored with a mass spectrometer. CO 2 uptake of sorbent was found to decrease with repeated exposure to steam. Characterization of the spent sorbent using N 2 physisorption, SEM, and thermogravimetric analysis (TGA) showed that the decrease in CO 2 loading can possibly be attributed to a reagglomeration of the amine in the pores of the silica. No support effect was found in this study. The commercial SiO 2 used, Cariact G10, was found to be stable under the conditions used. While it was found that subjecting the sorbent to several steam cycles decreased its CO 2 uptake, a continuous exposure of the sorbent to steam did not have a significant performance impact. A silanated sorbent, consisting of a mixture of PEI and aminopropyl-triethoxysilane on SiO 2 support, was also investigated for steam stability. Similarly to the nonsilanated sorbent, the CO 2 loading of this sorbent decreased upon steam exposure, although a mechanism for this change has not been postulated at this time.