Sulfur dioxide removal by mesoporous silica KCC-1 modified with low-coverage metal nitrates

The removal of sulfur dioxide (SO2) from flue gas using fibrous mesoporous silica KCC-1 synthesized via microwave-assisted hydrothermal method was observed. The sorbent was modified by introducing nitrate salts of sodium (Na) and calcium (Ca) at 5 wt. % metal loading via incipient wet impregnation method. The SO2breakthrough experiment was conducted in a vertical quartz-column reactor at atmospheric pressure and temperature of 323 K in the presence of 0.3 % SO2/N2. The SEM micrograph of KCC-1 exhibited a well-defined fibrous morphology consisting of colloidal spheres of 240-1160 nm in diameter. Addition of metal nitrates resulted in the reduction of surface area, total pore volume and minor breakage of the silica framework. The adsorption capacities of all samples were measured at C/C0= 0.5, where the addition of sodium (Na5/KCC-1) and calcium (Ca5/KCC-1) enhanced the removal capacity by 1.88 and 2 times higher than the parent KCC-1 respectively. Even though sodium is expected to achieve better removal capacity due to its higher basicity and dispersion related to the lower crystallite size, its performance ultimately suffered from significant agglomeration of sodium oxide which created pore blockage, subsequently resulting in poor accessibility to the active sites.