The Properties of AuSiO2 Nanoparticles with Oriented Channel in Benzyl Alcohol Oxidation

M. Ng , Prof. M. Meneghetti , E. Catari , S. PengSUNY Binghamton, Federal University of Alagoas,

State University of New York at Oswego

Conclusion References

Acknowledgements

Introduction Methods

Objectives

Results

Characterization of AuSiO2

I. Scanning Microscope Images(SEM) & Transmission Microscope Image (TEM)

II. UV-vis Spectrum

The objectives of the project include:- Synthesis and characterization of gold nanoparticles hollow mesoporous silica spheres with oriented channels - The catalytic characterization of the prepared gold nanoparticles in the oxidation of benzyl alcohol

400 450 500 550 600 650 700 750 800 850 9000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Wavelength (nm)

Abso

rban

ce

III. FTIR Spectrum (after calcination)

50010001500200025003000350040000

10

20

30

40

50

60

70

80

90

100

Wavelength (cm -̂1)

Tran

smitt

ance

(%)@ 2800-3000cm^-1,

organic side products are removed with calcination. @ ~ 3740cm^-1,

assigned as Si-OH.

IV. BET – Relative pressure vs. Volume

0.00E+00 2.00E-01 4.00E-01 6.00E-01 8.00E-01 1.00E+00 1.20E+001.2

1.4

1.6

1.8

2

2.2

Relative Pressure

log

of V

olum

e at

STP

(cc/

g)

BET Surface Area =102.161 m²/gPore Volume = 0.250 cc/g

Pore Radius Dv(r) = 20.653 Å

V. Catalytic Properties in Benzyl alcohol oxidation

I. Preparation of AuNPs -9.16mL of HAuCl4 dissolved in H2O to make a 150mL solution

- Addition of 3% w/w sodium citrate, reflux for 30 minutes - 64mg of PVP dissolved in H2O added after reflux, stir for 24 hrs -Centrifugation

II. Preparation of silica coating on AuNPs- 460mL of isopropanol, 66mL of H2O, 12.8mL of ammonia

- Nanoparticles collected from centrifugation added to solution- Addition of 0.4mL of TEOS, mixture stirred vigorously for at least 8 hours- The silica coating is important in maintaining the AuNPs in nanoscale-sized.products at 550°C for 360 minutes (1°C/min)

III. Prepartion of Au@HMSS (oriented channels)- 0.7504g of CTAB in 150mL of water 150mL of ethanol, and 2.75mL of ammonia- Stir for 24 hours at room temperature- Centrifugation to obtain nanoparticles- Dry in oven at 80-85°C. Calcinate to eliminate organic side

Nanoparticles, elements with the size of 1-100nm, have different properties and behaviors. For example, gold nanoparticles (AuNPs) are very reactive and can be used as catalysts. One problem with nanoparticles is to maintain their size in nanoscale in reactions.

Benzyl alcohol is the most reactive reaction of alcohol. Due to the aromatic structure of benzyl, the dislocation of electrons is very easy to pull out the hydrogen from the -OH group, oxidizing the compound.

All additional catalytic results are still pending.

1. Balasubramanian, Suresh K.; et all. Characterization, purification, and stability of gold nanparticles. Biomaterials. 2010. 31. 9023-9030.2. Klitgaard, Soren.; et all. Aerobic oxidation of alcohols over gold catalysts: role of acid and base. Catal Lett. 2008. 213-2173. Miedziak, Peter.; He, Qian.; et all. Oxidation of benzyl alcohol using supported gold-palladium nanoparticles. Catalysis Today. 2011. 47-54.

The characterization results from FTIR, BET and UV-vis shows that the shape of the AuNPs with oriented channels are formed as expected. However, results on catalytic characterization are still pending. For future perspective, TGA, HPLC and GC can be used for more detailed characterization.

1h 2h 5h4h3h 6h

Interal diameter: 83.6nm External diameter: 192nm

1 22 3

1 2

3

OH+ O2

Cat.Au@SiO2

O

benzyl alcohol benzaldehyde