Tetraethylenepentamine-Modified Siliceous Mesocellular Foam (MCF) for CO2 Capture

Mesocellular silica foam (MCF) materials with different pore volumes were prepared and modified with tetraethylenepentatnine (TEPA) as sorbents for CO2 capture. The as-prepared sorbents were characterized by XRD, TEM, SEM, nitrogen adsorption/desorption, and FTIR. CO2 capture performances of the adsorbents were tested in a fixed-bed reactor equipped with an online MS. The results indicated that the pore volume of supports has great effect on the CO2 capture performance. With the increasing of pore volume as well as the window and cell sizes of the MCF, more TEPA can be loaded into the pores of MCF. For MCF with larger pore volume, more unoccupied space is left after the same amount of TEPA was loaded into the pores. The unoccupied space is beneficial for higher CO2 uptake because the mass transfer limitation can be reduced to some extent and the interaction between CO2 and TEPA may be easier. MCF material with largest pore volume exhibited the largest CO2 uptake of 4.34 mmol/g of adsorbent with a 70 wt % TEPA loading tested by the fixed-bed reactor and at least 4.57 mmol/g tested by thermogravimetric analysis (TGA) under the conditions of 10.0% (v/v) CO2 in N-2 at 75 degrees C. Repeated adsorption/desorption cycles revealed that its high CO2 capacity can be regenerated via temperature swing adsorption and so it may be useful for CO2 capture via TEPA functionalized MCFs.