Photon Factory Activity Report 2004 #22 Part B (2005)
Chemistry

10B/2002G265

Cu2O as active species in the steam reforming of methanol over CuO/ZrO2
Hisayuki OGUCHI, Saburo HOSOKAWA, Seiichiro IMAMURA, Hiroyoshi KANAI*
Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan

Results and discussion
The summary of XRD data on CuO/CeO2 and CuO/
ZrO2 catalysts is as follows: (1) the starting coppers wereCuO, (2) the coppers of the post-reacted CuO/ CeO2 with
15-80 wt% loading were metallic Cu, (3) the coppers ofpost-reacted CuO/ZrO2 with 15-40 wt% loading weremetallic Cu, (4) those with 80-90 wt% loading were Cu2O.
The structures of typical catalysts, 80 wt% CuO/ CeO2
and CuO/ZrO2, were analyzed. Their XANES spectra
were different in the pre-edge region(Fig. 1). The XANES
spectrum of CuO/CeO2 is almost the same as that ofmetallic Cu. However, the spectrum of CuO/ZrO2
resembles that of Cu2O. The second derivative of theXANES(Fig. 2) indicates that all of copper species in thepost-reacted 80 wt% CuO/ZrO2 are Cu2O. The catalyst
gave no XRD patterns of ZrO2, resulting in highly
dispersed in abundant copper species. Highly dispersed
ZrO2, which is monoclinic from its FT spectrum, exerts
all of copper species kept as Cu2O irrespective of thereducing conditions. The XANES spectrum of postreacted CuO/ CeO2/ZrO2(8: 1: 1) was the mixed spectrumof metallic Cu and Cu2O, their catalytic activity was
higher than those of CuO/CeO2 and CuO/ZrO2.

ab8980 9000 9020 9040
Energy/eVFig. 1 XANES spectra of post-reacted 80
wt% CuO/CeO2 and CuO/ZrO2 catalysts

2nd Derivative

Experimental
An aqueous solution containing known amounts ofcopper(II) nitrate, cerium(III) nitrate or zirconium(IV)oxynitrate was stirred at 80 °C for 20 min and 3 N NaOH
was added until the pH of the solution was 11. The
precipitate obtained was filtered and washed with
deionized water three times. After drying at 353K
overnight, it was calcined at 573K for 3 h. The steam
reforming reactions(MeOH : H2O : He = 4.5 : 6.8 : 16)
were carried out with a fixed bed reactor at 523K underatmospheric pressure. X-ray absorption measurements for
K-edge of Cu were done at the Beam Line 10B.

AbsorbanceIntroduction
Hydrogen is much in demand for the fuel cell. CuO/CeO2 and CuO/ZrO2 catalysts were very active for thesteam reforming of methanol (SRM)[1,2]. XRD diagrams
showed that the starting coppers were CuO, and coppers
in most catalysts were reduced to metallic Cu during
SRM. However, the post-reacted coppers of 80 or 90 wt%
CuO/ZrO2 were Cu2O, while those of CuO/ZrO2 having
less than 40 wt% loading were metallic Cu. The oxidation
states of Cu in the post-reacted catalysts depended upon
CuO loading and water/MeOH ratio in SRM. The
catalytic active copper species in CuO/CeO2 and CuO/
ZrO2 have been elucidated from their XANES spectra.

Cu2O

0.10

Cu metal
0.05

CuO/ZrO2

0.00

-0.05
8960

9000

9040

Energy/eVFig. 2 The second derivatives of the XANES
spectra of post-reacted 80 wt% CuO/ ZrO2,metallic Cu, and Cu2O.
References[1] H. Oguchi, T. Nishiguchi, T. Matsumoto, H. Kanai, K.
Utani, Y. Matsumura, S. Imamura, Appl. Catal. A,281(2005) 69.
[2] H. Oguchi, H. Kanai, K. Utani, Y. Matsumura, S.
Imamura, submitted for publication in Appl. Catal. A.
* kanai@kit.ac.jp

Users' Report

21