Synthesis, Characterization, Activities And Technology Of Novel Materials For Catalytic Oxidations In Green Chemistry

About a quarter of the industrial production of monomers and chemicalintermediates is made using selective oxidation processes on solid catalysts andthere is thus wide basic and applied interest for this area of the research. Most ofthe catalysts used in these industrial processes are well established, but there isstill need for further (minor) improvements based on both better engineering ofthe process (reactor design, in particular) and better tuning of catalyst reactivityand properties. There are also some clear driving forces which stimulate newbreakthroughs in this area and thus the development of new processes andcatalysts: (i) the use of new, more economical, raw material and (ii) theecological issue. An example of a recent breakthrough in the field of selective oxidation isthe discovery of Ti-silicalite (TS-1) and its applications, which also stimulateda large and more general interest on the use of transition metal containingmicroporous materials for liquid phase heterogeneous conversion ofhydrocarbons using either H2O2 or other peroxo compounds. But one V吉林大学博士学位论文disadvantage of TS-1 catalyst is that its pore size (generally less than 6 ?) is toosmall to allow bulky reactants access to the active sites in the micropores of thezeolite, while the kind of bulky reactants dominate most of the chemicaltransformations which are of central importance in the fine chemical andpharamaceutical industries. Therefore, novel porous titanosilicates with largerpore size have always been sought. The ordered porous silica materials with the size from 1.5 to 2.5 nm areimportant in catalysis because most substrates in organic reactions are less than2.5 nm, however such materials are relatively scarce. Recently, orderedmesoporous silica materials with various pore size (2.1-5.0 nm) have beensuccessfully synthesized from various crystallization temperatures using blockcopolymer surfactant as a template, but it is difficult to obtain the materials withpore size less than 2.0 nm, due to the limitation of hydrocarbon chains (largerthan C8) for copolymer surfactants. If hydrocarbon chains are shorter than C8in copolymer surfactants, the hydrophobicity of hydrocarbon chains is notenough for the formation of the surfactant micelle. We demonstrate here that when a semi-fluorinated surfactant (FSO,CF3(CF2)4(EO)10) is used as the template, ordered mesoporous silica-basedmaterials with tailorable size from micropore to mesopore (1.6-5.1 nm) aresuccessfully synthesized from various crystallization temperatures (R.T.-100°C)in both strongly acidic (JLU-14) and neutral conditions (JLU-15). Obviousfeatures for semi-fluorinated surfactant syntheses of ordered mesoporous silicamaterials are as follows: (1) Tailorable pore size from 1.6 to 4.0 nm, estimatedby BJH and TEM methods; (2) pH value for synthetic system is extended toneutral condition; (3) Thicker porous walls, showing high hydrothermal andmechanical stability. Particularly, these materials such as JLU-14 exhibit much VI吉林大学博士学位论文higher mechanical stability than SBA-15 and MCM-41; (4) Very large surfacearea. For example, the surface area of JLU-1560 is as high as 1500 m2/g; (5)Heteroatoms such as Ti species are easily introduced into mesoporous silicamaterials. Semi-fluorinated surfactant synthesis under neutral condition canprepare the ordered mesoporous silica materials incorporated with a largeamount of heteroatoms. Furthermore, the semi-fluorinated surfactant synthesis should not be limitedto the use of FSO, and many semi-fluorinated surfactants are candidates if onlythey can effectively form regular micella in solution. For example, whenanother semi-fluorinated surfactant (FSN) is used as the template, disorderedmesoporous silica-based materials have been prepared in both strongly acidic(JLU-11) and neutral conditions (JLU-12).