Titanium-Doped Solid Core-Mesoporous Shell Silica Particles: Synthesis and Catalytic Properties in Selective Oxidation Reactions

Abstract

Near monodisperse spherical particles composed of a nonporous silica core covered by a Ti-doped hexagonally arranged mesoporous silica shell, Ti-SCMS, as well as spherical submicron-size particles of Ti-MCM-41, have been synthesized for the first time and characterized by elemental analysis, N 2 adsorption, XRD, TEM and DR-UV spectroscopy. The mesoporous Ti,Si-shell has a thickness of about 45 nm and incorporates isolated Ti centers in tetrahedral coordination. Catalytic properties of Ti-SCMS and Ti-MCM-41 have been studied in selective oxidation of three representative bulky organic substrates, 2,3,6-trimethylphenol, methyl phenyl sulfide and caryophyllene, with aqueous H 2 O 2 in MeCN medium. Ti-SCMS appeared to be more active and selective in the H 2 O 2 -based selective oxidation reactions compared to Ti-MCM-41, thus demonstrating an advantage of conducting a catalytic process in a thin mesoporous Ti,Si-shell.

Core–shell nanoparticles: synthesis and applications in catalysis and electrocatalysis

“…4.2.1. 340 For catalytic studies, SiO 2 @Pd(R)/TiMSS and SiO 2 @Pd(S)/ TiMSS (where (R) denotes random and (S) designates the surface) were investigated for one-pot generation of hydrogen peroxide (H 2 O 2 ); the concentration of H 2 O 2 in the reaction medium is almost independent of the catalysts used (Fig. Yamashita and co-workers synthesized Pd NPs supported on SiO 2 nanosphere core coated with a Ti-containing mesoporous silica shell (Pd/SiO 2 @TiMSS) 336 for one-pot oxidation of sulfide to sulfoxide.…”

“…31a). 340 For catalytic studies, SiO 2 @Pd(R)/TiMSS and SiO 2 @Pd(S)/ TiMSS (where (R) denotes random and (S) designates the surface) were investigated for one-pot generation of hydrogen peroxide (H 2 O 2 ); the concentration of H 2 O 2 in the reaction medium is almost independent of the catalysts used (Fig. 31b).…”

Magnetically separable titanium-silicate mesoporous materials with core–shell morphology: synthesis, characterization and catalytic properties

“…Recently, we have modified the procedure of Yoon and prepared a catalytically active material, Ti-SCMS, with near monodisperse spherical particles composed of a nonporous silica core covered by a titanium-silicate mesoporous shell (45 nm). 20 The shell had hexagonally ordered mesopores oriented perpendicularly to the core surface. The Ti-SCMS material revealed a superior catalytic performance in liquid phase H 2 O 2 -based oxidation of some bulky organic substrates compared with Ti-MCM-41 submicronsize particles, thus demonstrating the advantage of running a catalytic reaction in a thin uniform mesoporous shell.…”

Metal Complexes Immobilized on Magnetic Nanoparticles

“…A range of novel materials based on titanium silicate mesoporous solids have been recently reported by Barmatova et al [9,10]. These materials were prepared following the so-called solid core-mesoporous shell morphology synthetic approach, originally developed by Yoon et al [11].…”