Studies On Synthesis, Characterization And Catalytic Performance Of Highly Stabilized Mesoporous Molecular Sieves

Mesoporous molecular sieves have attracted considerable attention of the researchers since they were discovered. Owing to that the mesoporous molecular sieves have large specific surface area, one dimensionally linear and uniform channel structure, and the adjustable pore size ranging in 1.5-10 nm, it has been found that they have widely potential applications in the fields of heterogeneous catalysis and adsorption and separation. But the worse thermal and hydrothermal stabilities of mesoporous molecular sieves limited their application. In this paper, the main research target is to look for synthesis method of mesoporous molecular sieves with high thermal and hydrothermal stabilities and to characterize the as prepared mesoporous molecular sieves and their catalytic properties.A two-step methodology was applied to the synthesis of the mesoporous molecular sieves in the present researches. By this method, Co- or Ni-containing mesoporous molecular sieves with high thermal and hydrothermal stabilities were synthesized. Meanwhile, a novel method was carried out by introducing lamellar materials into the pore walls of mesoporus molecular sieves in order to increase their thermal and hydrothermal stabilities. Ni-containing mesoporous molecular sieves with high thermal and hydrothermal stabilities were successfully synthesized by using Ni-containing saponite as a precursor; mesoporous molecular sieves with high thermal and hydrothermal stabilities were synthesized using natural clay as a raw material; titanium oxide mesoporous molecular sieves were also synthesized by hydrothermal method.The synthesized mesoporous molecular sieves were characterized by the means of XRD, FT-IR, TEM, TPR, AFM, TG/DSC, BET, and element analysis. The results show that well ordered mesoporous molecular sieves were synthesized and that the template agent was efficiently removed after calcination at 550℃. The thermal and hydrothermal stabilities of the synthesized mesoporous molecular sieves can be enhanced by two-step method. MCM-41 mesoporous molecular sieves had still mesoporous structure after calcination at 850 ℃ for 3h and the mesoporous structure was not damaged after hydrothermal treatment at 100℃ for 10 d. Ni- and Co-containing mesoporous sieves had certain thermal and hydrothermal stabilities. The thermal hydrothermal stabilities of mesoporous molecular sieves were affected by the sequence of adding materials. The particle sizes of Co-containing mesoporous sieves can be controlled by the two-step method, i.e. nanosized Co-containing mesoporous sieves can be synthesized. Ni-containing...