Small-scale hydrogen production from propane

doi:10.1016/j.cattod.2004.09.078

Catalysis Today

Volume 100, Issues 3–4, 28 February 2005, Pages 457-462

https://doi.org/10.1016/j.cattod.2004.09.078 Get rights and content

Abstract

Partial oxidation and oxidative steam reforming of propane were investigated over 0.01 wt.% Rh/Al₂O₃ foam catalysts. High selectivity to hydrogen was obtained for both reactions, but addition of steam to the reactant mixture gave higher selectivity to hydrogen. Stability tests over 7 h revealed that the catalytic activity of Rh was quite stable under partial oxidation conditions. Higher loss in Rh activity was observed when steam was present in the reactant mixture. FE-SEM images showed that Rh particle size and distribution are modified under partial oxidation and oxidative steam reforming conditions. However, these changes were more distinct on the catalyst used for oxidative steam reforming.

Introduction

Hydrogen is important in oil refineries and the chemical industry, and it is becoming attractive as a clean fuel for combustion processes and fuel cells. Conversion of lower alkanes by catalytic partial oxidation at short contact times is one promising route for hydrogen or synthesis gas production.

The short contact time regime obtained using various structured catalysts [1], [2], [3], [4] is particularly suitable for fast oxidation reactions [5], [6], [7], [8]. Several studies devoted to oxidation reactions of light hydrocarbons concluded that Rh is one of the most suitable catalysts for the production of hydrogen [9], [10], [11], especially if performed in a short contact time regime [12], [13], [14], [15], [16].

An essential property required for catalytic systems for production of hydrogen is stability under oxidising conditions. It has been reported that Rh-coated α-Al₂O₃ foam catalyst did not show activity loss at 1000 °C over several hours [12]. The stability and selectivity to hydrogen of reducible- and irreducible-oxide supported rhodium catalysts was investigated for partial oxidation of methane by Ruckenstein and Wang [17]. It was concluded that irreducible-oxides (MgO, γ-Al₂O₃, SiO₂, Y₂O₃, La₂O₃) are suitable supports with high stability due to strong interactions with the rhodium. The strong metal–support interaction between rhodium and alumina support, inhibiting sintering and growth of large of rhodium oxide particles below 900 °C, was also reported by Beck et al. [18]. Rh/Al₂O₃ was found to have the highest stability of all tested catalysts (Rh, Ru, Pd, Pt, Ni, Co supported on Al₂O₃) for hydrogen production by steam reforming of 2-propanol at 400 and 500 °C [19].

In our work, Rh-impregnated alumina foams have been tested for catalytic partial oxidation and oxidative steam reforming of propane as potential high-throughput structured catalysts. The main subject of this paper is the stability of the Rh foam catalyst. Furthermore, the structural details of the catalysts and possible changes under the conditions applied have been investigated using field emission scanning electron microscopy (FE-SEM). Finally, we wish to establish to which degree any structural changes can be directly linked to changes in activity and selectivity.

Section snippets

Experimental

Rh structured catalysts were prepared by impregnation of extruded alumina foams of 84% porosity (Goodfellow) with 99.5% nominal purity. Cylindrical foam pieces (3 mm i.d., 15 mm o.d., 12.7 mm length) were cut and then impregnated in Rh(NO₃)₃·2H₂O solution to obtain a final Rh loading of 0.01wt.%, as estimated by the solution uptake. The impregnated foams were dried at 100 °C for 1 h and calcined in flowing air at 600 °C for 4 h. Reduction was performed in situ at 700 °C for 1 h in a flow of hydrogen

Results and discussion

Conversion of reactants and selectivity to main products during partial oxidation (POX) and oxidative steam reforming (OSR) of propane over the Rh/Al₂O₃ foam catalyst are shown in Fig. 1A and B, respectively, as a function of furnace temperature. Aspects of temperature, residence time, pressure and contributions from homogeneous reactions are discussed elsewhere [20], but some main conclusions are summarised below. Oxygen and propane conversion increased with temperature, and was complete at 700

Conclusion

Rh-impregnated (0.01 wt.%) Al₂O₃ foam catalysts are active for both partial oxidation and oxidative steam reforming of propane. The highest selectivity to hydrogen (0.92) relative to propane converted at almost complete propane conversion (0.96) was obtained by oxidative steam reforming at 700 °C. Higher stability and lower selectivity (0.72) of the 0.01wt.% Rh/Al₂O₃ catalyst was observed for POX than for OSR, indicating that the presence of steam in the reaction mixture is the strongest cause of

Acknowledgement

The financial support from the Research Council of Norway is gratefully acknowledged.

References (20)

J.L. Williams
Catal. Today
(2001)
I.M. Lachman et al.
Catal. Today
(1992)
R.M. Watwe et al.
J. Catal.
(1998)
M. Fathi et al.
Catal. Today
(1998)
R. Lødeng et al.
Appl. Catal. A: Gen.
(1999)
B. Silberova et al.
Appl. Catal. A: Gen.
(2004)
A. Beretta et al.
Chem. Eng. J.
(2004)
S.S. Bharadwaj et al.
J. Catal.
(1994)
P.M. Torniainen et al.
J. Catal.
(1994)
E.P.J. Mallens et al.
J. Catal.
(1997)

There are more references available in the full text version of this article.

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Small-scale hydrogen production from propane

Abstract

Introduction

Section snippets

Experimental

Results and discussion

Conclusion

Acknowledgement

Catal. Today

Catal. Today

J. Catal.

Catal. Today

Appl. Catal. A: Gen.

Appl. Catal. A: Gen.

Chem. Eng. J.

J. Catal.

J. Catal.

J. Catal.