(445f) High Performance of Novel Kinds of Mesoporous Rare Earth Phosphates in Vapor O-Methylation of Hydroxybenzenes

Abstract: Porous materials have some good characters. For mesoporous materials, they have larger channels(2~50 nm) than zeolites, which make them are of high relevant for the catalytic application to the direct activation of large organic molecule or for supporting active sites bearing large organic functionalities. Rare earth phosphates have been extensively studied in optical materials, sensors, ceramic materials and heat-resistant materials, etc. However, there is still little research in mesoporous rare earth phosphates(MREP), which might be caused by the reasons that the prepared MREP are very unstable, or the application of MREP is limited. In this study, novel kinds of rare earth phosphates with a mesoporous microstructure have been prepared by template method. In a typical preparation, Rare earth(III) (La, Eu, Ho, Yb, Er) oxide was dissolved in concentrate HCl or HNO3, then the solution was heated to remove water and all other volatiles. Then the resulting solution was diluted in ethanol and the template P123 was added. The mixture was heated to evaporate ethanol slowly and the result solid was calcined to obtain the final MREP (Fig. 1). The application of this kind of rare earth phosphates in o-alkylation of hydroxybenzenes was investigated. This is a series of reactions, such as o-alkylation of phenol with methanol to anisole, o-alkylation of catechol with methanol to guaiacol, etc. Conventionally, these kinds of products were synthesized by Williamson ether synthesis, which require the corresponding alkyl halide and a stoichiometric amount of sodium hydroxide or by using dimethylsulphate. The convention method will cause environmental problems and produce wastes. The use of solid catalysts will solve the above problems and be a green chemical method. The comparison of performance of mesoporous catalysts and the catalysts prepared without templates has been studied(Fig.2). The higher performance of mesoporous materials would be ascribed to their porous structure and much more amount of surface active sites.