In this study, porous precipitated silica (PPS) was synthesized using sodium silicate as an inexpensive silica precursor and then
impregnated with various amines such as 2-aminomethylpropanol (AMP), monoethanolamine (MEA), diethanolamine (DEA)
and polyethyleneimine (PEI) to produce amine-impregnated solid adsorbents, which will be evaluated as a sorbent for CO2
capture. Major parameters and performances of adsorbents including thermal stability, adsorption capacity, heat capacity, and
adsorption heat were investigated. The results indicated that MEA impregnated PPS (60 wt%) has the highest CO2 adsorption
capacity; up to 233 mg/g, while the adsorption capacity of PEI impregnated PPS (60 wt%) is 136 mg/g. The heat capacity of PEI
impregnated PPS (50 wt%) is relatively low (1.68 J/go·C) compared to that of aqueous MEA 30 wt% (3.98 J/go·C). Obtained
results were used to calculate the energy requirement for adsorbent regeneration. The calculated results revealed that PEI
impregnated PPS (50 wt%) requires the least energy for regeneration, only 2080 kJ/kg of CO2 and it is 44.7 % lower than energy
requirement for aqueous MEA 30 wt%. Thermal stability of the adsorbents was confirmed by thermal gravity analyses, which
showed that AMP and MEA start vaporizing at very low temperature and complete at 110 and 120 oC, DEA vaporizes at
temperature from 100ņ200oC, and PEI vaporizes and decomposes at about 250ņ400 oC. The study on adsorption/desorption
performance at the regeneration temperature of 90 oC indicated that the stability of the sorbent is greatly varied with the
vaporization temperature. PEI impregnated PPS shows a no significant loss in CO2 adsorption capacity, while DEA impregnated
PPS lost 12 % of adsorption capacity after 10 cycles.
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