Stability and hydrothermal synthesis of Co-MCM-41 mesoporous molecular sieves

Hexagonal Co-MCM-41 mesoporous molecular sieves with different contents of cobalt were synthesized by hydrothermal method and using sodium silicate and cobalt chloride as raw materials. The physicochemical properties of the samples were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), inductive coupled plasma (ICP) technique, temperature programmed reduction (TPR), transmission electron microscopy (TEM) and N2 physical adsorption, respectively, to investigate the thermal and hydrothermal stabilities of the Co-MCM-41 samples. The experimental results show that Co-MCM-41 mesoporous molecular sieves are successfully synthesized under hydrothermal condition, with specific surface area in the range of 809.8-1257.2 m2/g and average pore size in the range of 2.7-2.8 nm. Specific surface area and pore volume of the synthesized Co-MCM-41 mesoporous molecular sieve decrease with the increase of cobalt content doped, and the mesoporous ordering becomes poor. The results of thermal and hydrothermal tests show that the mesostructure of Co-MCM-41 mesoporous molecular sieve after calcination at 750 ℃ for 3 h is damaged. On the other hand, the framework of Co-MCM-41 mesoporous molecular sieve still retains after hydrothermal treatment at 100 ℃ for 5 d, but the mesoporous ordering is poor.