LAUSR

Abstract Organosilanes with different head groups and chemical properties, including phenyltriethoxysilane (PTES), aminopropyltriethoxysilane (APTES), and trimethylchlorosilane (TMCS), were used to modify the adsorption properties of diatomite (DE). Characterizations of the as-synthesized samples were investigated by scanning electron microscopy (SEM), infrared spectroscopy (IR), thermogravimetric analysis (TGA), nitrogen adsorption–desorption and solid-state 29Si magic angle spinning nuclear magnetic resonance (MAS NMR). SEM imagines show that the morphology of DE was remained during the modification. IR spectra provide clear evidence that they were indeed modified as intended. The results of TGA show that the weigh losses of all samples were increased after silylation. And the MAS NMR indicated that large amounts of isolated silanols condense with the organolsilanes, which further proved the organic groups have been loaded onto the diatomite. The adsorption experiments of methane by raw and three modified diatomite were also studied. Results showed that the adsorption amount increases constantly with the increasing of pressure and the equilibrium have not been reached at the room temperature. The adsorption data indicate that the sorption of CH4 on modified products and diatomite are dominated by multilayer coverage and they all fit the Freundlich isotherm equation well. The PTES-DE and APTES-DE have excellent CH4 adsorption capacity and they can reach the adsorption target proposed by DOE far below 35 bar, at 3 bar and 7.5 bar respectively. These two materials exhibit excellent adsorption performance for CH4 and have the potential to provide improved methods for reducing greenhouse gas emissions.