Amine-modified ordered mesoporous silica: The effect of pore size on CO2 capture performance

Abstract

The objective of current research is to investigate the effect of pore size of mesoporous silica supports on the CO2 capture performance of solid amine sorbents. Two ordered mesoporous silicas (OMS) with different pore sizes (5.6nm and 7.6nm) were synthesized as tetraethylenepentamine (TEPA) supports. A serious of techniques, such as physical adsorption, infrared spectroscopy and thermal gravimetric analysis were used to characterize the solid amine sorbents. The CO2 capture performances of the sorbents were evaluated using breakthrough method with a fixed-bed reactor equipped with an online mass spectrometer. The experimental results indicate that the pore size has significant influence on CO2 capture performance. Larger pore size could decrease the mass transfer resistance and increase the interaction between CO2 and TEPA. Therefore, OMS-7.6 is better than OMS-5.6 as amine support. The highest CO2 sorption capacities achieved with OMS-7.6 with 50wt% TEPA loading (OMS-7.6-50) in the absence and presence of moisture are 3.45mmol/g and 4.28mmol/g, respectively, under the conditions of 10.0% CO2/N2 mixture at 75°C. Cyclic CO2 adsorption–desorption experiments indicate that the solid amine sorbents are fairly stable and regenerable.