Porous Silica Loaded with Polyethylenimine and Diethanolamine for CO ₂ Capture from Kitchen Flue Gas

CO2 adsorption is a key technology for carbon capture. Current applications primarily focus on large-scale industrial CO2 emission sources, while the capture from distributed sources, especially kitchen flue gas, has been ignored. The kitchen flue gas is featured by low CO2 concentrations, high humidity, and high concentrations of volatile organic compounds. Such a complex composition leads to competitive gas adsorption and rapid degradation of the adsorbent performance. Herein, to solve this problem, xP/D-carrier adsorbents are synthesized by coloading polyethylenimine and diethanolamine onto the three SiO2 carriers (fumed silica, hierarchically porous SBA-15, and mesostructured KIT-6). Among them, 0.9P/D-KIT-6 performs the best chemical CO2 adsorption capacity of 2.22 mmol/g at 348 K and 1.0% (vol.) CO2 concentration, showing excellent thermal stability and ultrahigh CO2/N2 selectivity of 1030. Breakthrough tests with simulated kitchen flue gas show that xP/D-carrier adsorbents maintain high CO2 adsorption selectivity under elevated temperatures and complex gas environments.