Mesoporous Material Mcm-41 Structure Control And Application Performance

MCM-41 is one member of the family of mesoporous M41s that was first synthesized in 1992. With the clarification of its mechanism of formation and structural characteristics, recent research on MCM-41 has been gradually focused on modifying its structures, improving its performances and exploring potential applications. However,no breakthrough has been achieved up to date. In view of this situation,this dissertation study is mainly involved in two aspects: 1) Adjustment and control of the structures of MCM-41. 2) Studies on the performances of MCM-41 in different applications.1. Adjustment and control of the structures of MCM-41On the one hand, taking advantage of the substitutability of the framework and the modifiability of the surface,the structural characteristics and the surface properties of MCM-41 were adjusted on the basis of understanding the mechanism of formation. On the other hand,the shortcomings in the structures and the properties of MCM-41 have been overcome to some extent.1) The mechanism of formation was first investigated from view point of the effects of the synthesis conditions on the long-range order structure of MCM-41. It has been concluded that under the experimental conditions the hexagonal-ordered structure of MCM-41 is formed through a cooperative interaction between the inorganic anions and surfactant cations,and not via a lamellar mesophase.2) Isomorphous substituted MCM-41 materials with well-ordered structures were hydrothermally synthesized by adding Al or Ti,Fe,Ni and Cr compounds to the silicate species. Not only do the characteristics of long-range and local structures vary with the nature and amount of the substituting elements,but the characteristics of the pore structure can also be adjusted to some extent by isomorphous substitution. In addition to substitution of framework Si,the pore characteristics of MCM-41 can also be adjusted by post-synthesis dispersion of metal oxides on the interior surface of MCM-41.3) The surface acidity and the surface hydrophilicity/hydrophobicity of MCM-41 were altered,taking advantages of the substitutability of the framework and the modifiability of the surface. The results of pyridine-TPD indicate that the surface acidity of MCM-41 increases after inserting Al or transition metal elements into the framework and the post-synthesis dispersion of metal oxides. The results of benzene-TPD show that the surface hydrophobicity of MCM-41 decreases after inserting Al or transition metal elements into the framework and the post-synthesis dispersion of metal oxides.4) A potential method of overcoming the instability of MCM-41 which results from the...