Recent Developments in Gold Nanomaterial Catalysts for Oxidation Reaction through Green and Sustainable Routes - Advanced Materials for Agriculture, Food and Environmental Safety - page 205

Au
<110>

TiO 2
<201>

Figure 8.5 (Let ) Transmission electron micrograph for Au/TiO2 contact interface and
(Right) its schematic diagram. Reproduced with permission from [68].

0.2

Au/Ti-SiO 2 D645
(total counts: 354)

0.15

0.1

d = 4.42 nm

σ = 1.13

0.05

0

0 24681012

Particle Diameter (nm)

14 16 18 20

Figure 8.6 HRTEM photograph of Au/Ti-SiO 2 catalyst and particle size distribution of
gold. (Obtained from presentation of X. Nijhuis, Eindhoven University of Technology).

Ti-HMM, Ti-SiO 2 was up to 4-5%. It is found that titanium-incorporated
conventional mesoporous silica was very ef ective in producing PO with
high selectivity. Among the dif erent parameters, the catalyst preparation
(i.e., gold deposition), washing with water and calcination temperature
had a signii cant ef ect on the activity of the catalysts for propylene epoxi-
dation. h e silylated three-dimensional mesoporous titanosilicate material
was very promising for producing PO up to 8% yield. h is probably sug-
gests that the distance between two neighboring Ti cations in Ti-O-Ti enti-
ties may determine the optimal reaction temperature to some extent. h e
mesoporous titanosilicate discovered by Sinha et al. [80] could raise the
PO yield up to 9% at er silylation and using Ba(NO 3 ) 2 promoter.
h e major problem associated with a Ti-incorporated mesoporous silica
system is the fast deactivation of the catalyst. Uphade et al. [71] extracted
the organic compound from used Ti-MCM-48 catalyst and by GC-MS
studies and found many oligomarized products in the catalyst surface