Efficient CO2 capture on low-cost silica gel modified by polyethyleneimine

In this work, a series of polyethyleneimine (PEI) functionalized commercial silica gel were prepared by wet impregnation method and used as CO₂ sorbent. The as-prepared sorbents were characterized by N₂ adsorption, FT-IR and SEM techniques. CO₂ capture was tested in a fixed bed reactor using a simulated flue gas containing 15.1% CO₂ in a temperature range of 25–100°C. The effects of sorption temperature and amine content on CO₂ uptake of the adsorbents were investigated. The silica gel with a 30 wt% PEI loading manifested the largest CO₂ uptake of 93.4 mgCO₂/g_adsorbent (equal to 311.3 mgCO₂/g_PEI) among the tested sorbents under the conditions of 15.1% (v/v) CO₂ in N₂ at 75°C and atmospheric pressure. Moreover, it was rather low-cost. In addition, the PEI-impregnated silica gel exhibited stable adsorption-desorption behavior during 5 consecutive test cycles. These results suggest that the PEI-impregnated silica gel is a promising and cost-effective sorbent for CO₂ capture from flue gas and other stationary sources with low CO₂ concentration.