Structure and Catalytic Properties of the SiO-H Groups on SBA-15 Molecular Sieve: A Density Functional Theory Study

A DFT study on the structural and catalytic properties of the SiO-H groups on SBA-15 molecular sieve was carried out.The geometry and IR spectra data calculated are identical to the experimental data.The electrostatic potential maps of the model clusters show that the H atoms of the single O-H groups on the surface of SBA-15 are the L acid sites and the O atoms of the hydrogen-bonded O-H groups are the B basic sites.The frontier molecular orbitals demonstrate that the hydroxyl groups on the surface of SBA-15 provide the oxidability.Further,the strength of the B acid on the surface of SBA-15 was discussed by means of the deprotonation energy and Mayer bond order.