Synthesis, Characterization And Catalytic Properties Of Green Catalytic Materials

About a quarter of the industrial production of monomers and chemical intermediates is made using selective oxidation processes on solid catalysts and there is thus wide basic and applied interest for this area of the research. Most of the catalysts used in these industrial processes are well established, but there is still need for further (minor) improvements based on both better engineering of the process (reactor design, in particular) and better tuning of catalyst reactivity and properties. There are also some clear driving forces which stimulate new breakthroughs in this area and thus the development of new processes and catalysts: (i) the use of new, more economical, raw material and (ii) the ecological issue.An example of a recent breakthrough in the field of selective oxidation is the discovery of Ti-silicalite (TS-1) and its applications, which also stimulated a large and more general interest on the use of transition metal containing microporous materials for liquid phase heterogeneous conversion of hydrocarbons using either H2O2 or other peroxo compounds. But one disadvantage of TS-1 catalyst is that its pore size (generally less than 6 ?) is too small to allow bulky reactants access to the active sites in the micropores of the zeolite, while the kind of bulky reactants dominate most of the chemical transformations which are of central importance in the fine chemical and pharamaceutical industries. Therefore, novel porous titanosilicates with larger pore size have always been sought.We have prepared mesoporous titanosilicates with MFI structure by using assembled from TS-1 nanocluster with mesoporous carbon as hard-templates. Characterizations showed that the meso-structure of such titanosilicates were 2D hexagonal ordered and the micro-structure in the framework was MFI structure. Catalytic tests suggested that the catalytic activities of such mesoporous titanosilicates are comparable with TS-1 in both small and bulky molecular oxidation.It is well known that the Fe(III) is an effective redox metal, and the synthesis and characterization for iron substituted aluminophosphate (FeAPO) have been studied widely, but few catalytic results in catalytic oxidations by H2O2 have been reported. Iron substituted aluminophosphate molecular sieves (FeAlPO4-11, FeAlPO4-5 and FeVPI-5) have been hydrothermal synthesized. Catalytic data show that the activities of Fe-AlPO4-11, Fe-AlPO4-5 are comparable with that of TS-1 in the oxidation of aromatic compounds. Fe-VPI-5 shows high activity in naphthol hydroxylation by H2O2, while TS-1 is completely inactive due to the small pore size. Comparison of various catalysts proposed that Fe(III) in the framework is proposed as the major active sites in the catalytic reactions. 57Fe M?ssbauer spectra of FeAPO-5 and FeAPO-11 samples suggest that higher catalytic activity may be mainly resulted from Fe(III) in the framework of the molecular sieves.