Mesoporous silicas with enhanced pore structures were synthesized and PEI was immobilized in them to produce adsorbents for CO2.The prepared samples were characterized by N2 adsorption-desorption isotherms and small angle x-ray diffraction, and their CO2 adsorption performance were evaluated.CO2 adsorption capacity increased with operating temperature initially and then declined.CO2 adsorption capacity increased with PEI loading due to more amine sites created.The results show that the structure of support plays an important role in CO2 adsorption capacity.High surface area and large pore volume favor the CO2 adsorption capacity.The remaining template in MCF materials plays an important role in promoting CO2 adsorption capacity, which could be 3.24 mmol/g when the amount of PEI loading is 70% at 85C.Meanwhile the remaining template contributes greatly to the dispersion of PEI, resulting in higher adsorption capacity at low temperature.The effect of the amount of remaining template was studied and it was found that CO2 adsorption capacity decreases with increasing template.The CO2 adsorption capacities for mixed-amine modified MCFs are higher than those of the samples modified by PEI only, which was ascribed to the better dispersion of PEI.MCF modified with the mixing of 3-aminopropyltrimethoxysilane (APTMS) and PEI exhibited highest adsorption capacity of 2.67 mmol/g at 50C.These findings reveals that pore structure, PEI loading, PEI dispersion and remaining template work together to influence the CO2 adsorption performance.