Gold catalysts supported on mesoporous titania for low-temperature water–gas shift reaction

doi:10.1016/j.apcata.2004.04.030

Applied Catalysis A: General

Volume 270, Issues 1–2, 30 August 2004, Pages 135-141

https://doi.org/10.1016/j.apcata.2004.04.030 Get rights and content

Abstract

Mesoporous titania with high surface area and uniform pore size distribution was synthesized using surfactant templating method through a neutral [C₁₃(EO)₆–Ti(OC₃H₇)₄] assembly pathway. The different gold content (1–5 wt.%) was supported on the mesoporous titania by deposition–precipitation (DP) method. The catalysts were characterized by X-ray diffraction, TEM, SEM, N₂ adsorption analysis and TPR. The catalytic activity of gold supported mesoporous titania was evaluated for the first time in water–gas shift reaction (WGSR). The influence of gold content and particle size on the catalytic performance was investigated. The catalytic activity was tested at a wide temperature range (140–300 °C) and at different space velocities and H₂O/CO ratios. It is clearly revealed that the mesoporous titania is of much interest as potential support for gold-based catalyst. The gold/mesoporous titania catalytic system is found to be effective catalyst for WGSR.

Introduction

The mesoporous materials with different compositions, new pore systems and novel properties have attracted considerable attention because of their remarkably large surface areas and narrow pore size distributions, which make them ideal candidates for catalysts [1]. Recently, much attention has been paid to the synthesis of nanostructured mesoporous oxides using surfactant templating method. It has been developed for the synthesis of materials with a narrow mesopore size distribution and controlled pore structure [2], [3], [4], [5], [6]. Neutral templating route has important advantages because most metals form alkoxides or other neutral complexes suitable for hydrolysis and assembly as neutral inorganic precursors [7].

It is generally anticipated that the use of a high surface area mesoporous oxide support, rather than a commercial, low surface area support, for noble metals or transition metals has some beneficial effect on the catalytic performance [8].The mesoporous support would give rise to well dispersed and stable metal particles on the surface upon calcination and reduction and as a consequence would show an improved catalytic performance. It was suggested a good possibility to apply these materials for the first time as supports for gold catalysts. Mesoporous titania and zirconia have been found to be promising supports for gold-based catalysts in complete benzene oxidation [9].

The interest in gold-containing catalysts has very rapidly increased due to their high activity at low temperatures in a lot of important reactions [10], [11], [12]. Water–gas shift reaction (WGSR) has recently been attracting rapidly growing interest due to fuel cell power systems development and needs of pure hydrogen production. Moreover, WGSR is one of the key steps involved in the automobile exhaust processes, converting CO with water to hydrogen and carbon dioxide and including the produced hydrogen as a very effective reductant for NO_x removal. The catalytic activity and especially the stability of gold catalysts strongly depend on both the state and structure of the support and the specific interaction between gold and support. The type of the support is of crucial importance to the obtaining of highly dispersed gold particles and catalysts with good performance [13], [14]. It was found that Au/TiO₂ was selective to the formation of CO, namely, reverse WGSR [15]. Later, Au/TiO2 was confirmed to be active for water–gas shift reaction [16].

In this work we present a catalytic study of WGS gold catalysts supported on mesoporous titania. The methods of preparation of this nanomaterials and their characterization by XRD, TEM, SEM, N₂ adsorption analysis and TPR were described. The catalytic activity of the catalysts with different gold content was tested. The influence of space velocity and H₂O/CO ratio at different temperatures was investigated systematically.

Section snippets

Synthesis of mesostructured titania support

The mesoporous titania with high surface area and uniform pore size distribution was synthesized using surfactant [C₁₃(EO)₆–polyoxyethylene(6) tridecylether] templating method through a neutral [C₁₃(EO)₆–Ti(OC₃H₇)₄] assembly pathway [9]. The hydrothermal treatment was performed during 48 h at 60 °C. The template was completely removed after 48 h of ethanol extraction with the help a Soxhlet apparatus. The mesoporous titania was dried under vacuum at 80 °C.

Preparation of gold catalysts

Different gold content (1–5 wt.%), was

Results and discussion

The characteristics of the samples are listed in Table 1.

Conclusions

The study of WGS reaction over gold supported on mesoporous titania leads to the following conclusions:

•
A high and stable activity for gold/mesoporous titania catalytic system over a wide temperature range and at different space velocities and H₂O/CO ratios was established. This high and stable WGS activity could be related to the high stability of the gold dispersion.
•
The different loading, average particle size and dispersion of the gold strongly influence the catalytic activity. Higher

Acknowledgements

The authors VI and TT gratefully acknowledge financial support from the National Science Fund at the Ministry of Education and Science of Bulgaria (project X-1320).

References (30)

D Trong On et al.
Appl. Catal. A
(2001)
D Trong On et al.
Appl. Catal. A
(2003)
A Sayari et al.
Micropor. Mater.
(1997)
J.Y Ying et al.
Angew. Chem.
(1999)
J.Y Ying et al.
Angew. Chem. Int. Ed.
(1999)
S Velu et al.
Appl. Catal. A
(2003)
M Haruta
Catal. Surv. Jpn.
(1997)
M Haruta
Catal. Today
(1997)
D.Ch Andreeva et al.
Bulg. Chem. Commun.
(1998)
H. Sakurai, A. Ueda, T. Kobayashi, M. Haruta, Chem. Commun. (1997)...
G.R Bamwenda et al.
Catal. Lett.
(1997)
M. Haruta, in: Proceedings of the Gold 2003 Conference on New Industrial Applications for Gold, Vancouver, September...

M Haruta et al.

Appl. Catal. A

(2001)

M Haruta

Cattech

(2002)

J.L Blin et al.

Stud. Surf. Sci. Catal.

(2002)

J.-L Blin et al.

Angew. Chem. Int. Ed.

(2003)

W Yu-de et al.

Appl. Catal. A

(2003)

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Gold catalysts supported on mesoporous titania for low-temperature water–gas shift reaction

Abstract

Introduction

Section snippets

Synthesis of mesostructured titania support

Preparation of gold catalysts

Results and discussion

Conclusions

Acknowledgements

Appl. Catal. A

Appl. Catal. A

Micropor. Mater.

Angew. Chem.

Angew. Chem. Int. Ed.

Appl. Catal. A

Catal. Surv. Jpn.

Catal. Today

Bulg. Chem. Commun.

Catal. Lett.

Appl. Catal. A

Cattech

Stud. Surf. Sci. Catal.

Angew. Chem. Int. Ed.

Appl. Catal. A