Hexagonal hydrothermal synthesis

Titanium containing hexagonal mesoporous materials were synthesized by the modified hydrothermal synthesis method. The synthesized Ti-MCM-41 has hi y ordered hexa rud structure. Ti-MCM-41 was transformed into TS-l/MCM-41 by using the dry gel conversion process. For the synthesis of Ti-MCM-41 with TS-1(TS-1/MCM-41) structure TPAOH was used as the template. The synthesized TS-l/MCM-41 has hexagonal mesopores when the DGC process was carried out for less than 3 6 h. The catalytic activity of synthesized TS-l/MCM-41 catalysts was measured by the epoxidation of 1-hexene and cyclohexene. For the comparison of the catalytic activity, TS-1 and Ti-MCM-41 samples were also applied to the epoxidation reaction under the same reaction conditions. Both the conversion of olefins and selectivity to epoxide over TS-l/MCM-41 are found hi er flian those of other catalysts. 

The controlled hydrothermal synthesis of rare earth borates results in various nanostructures. The hydrothermal method at 300 °C yields submicron sized GdB03 Eu " powders (Wang et al., 2001a). Well-crystallized YBOsTu NCs were prepared by a mild hydrothermal method in the presence of urea, and a pure hexagonal phase could be obtained at a lower temperature of 200 °C (Jiang et al., 2003). 

V- Hexagonal MCM- lattice 41 VOSO4 Fumed silica Dodecyltrimethyl ammonium bromide Hydrothermal synthesis 100 °C, 6-7 days in Teflon-hned autoclaves tumbled at 25 rpm Sayari, 1995 (57)... 

Hydrothermal synthesis, on the contrary, resulted in nanotube [153] and nano-particle [177] morphologies, as well as in hexagonal star- and dendrite-like 2-D nanostmctures [144] (Figure 19.11a and b). In this case, Mn(N03)2 and Mn(S04)2 salts were used as the most common sources of Mn, with reaction temperatures ranging between 100 and 250 °C. Kim ef al. [143] reported that the addition of a polyvinylpyrolidone (PVP) polymer to the reaction mixture, in combination with the post-treatment (calcination), resulted in a thin layer of a-Mn203 phase covering... 

Y.L. Auyoong, P.L. Yap, X. Huang, S.B.A. Hamid, Optimization of reaction parameters in hydrothermal synthesis astrategy towards the formation of CuS hexagonal plates. Chemistry Central Journal 7 (2013) 67-79. 

Figures 4a and 4b depict selected Nitrogen adsorption-desoprtion isotherms and pore size distributions (PSDs) for the same series of samples. As seen here and also in Table 1, all hexagonal phases exhibited pore sizes mostly above 5 nm, while typical pore sizes of MCM-41 silica prepared in the presence of CTAB under more common temperatures, i.e., 80 - 120 °C, have 3.5 to 4 nm pores [5, 19]. Earlier work showed that direct synthesis or postsynthesis hydrothermal restructuring in the mother liquor at high temperature, e.g. 150 °C gave rise to...

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