Experimental and numerical study on the kinetics of CO2–N2 clathrate hydrates formation in silica gel column with dodecyltrimethylammonium chloride for effective carbon capture

•CO2–N2 hydrates formation kinetics in silica gel column with DTAC are studied.•A shrinking core model is built to reveal the roles of pores, DTAC, and N2.•CO2 separation factor is greatly improved by 77.5% with 0.6- wt% DTAC.•Pore sizes affect diffusion rate constant more significantly than reaction rate constant.•The porosity of the hydrate shell changes with the addition of DTAC.