Aqueous-phase reforming of ethylene glycol on Co/ZnO catalysts prepared by the coprecipitation method

doi:10.1016/j.molcata.2010.11.024

Journal of Molecular Catalysis A: Chemical

Volume 335, Issues 1–2, 1 February 2011, Pages 129-135

https://doi.org/10.1016/j.molcata.2010.11.024 Get rights and content

Abstract

Co/ZnO catalysts with different Co/Zn ratios have been prepared by the coprecipitation method. It is revealed that below the nominal Co/Zn molar ratio of 2, the calcined Co/ZnO samples were constituted by ZnO and ZnCo₂O₄ spinel. At the nominal Co/Zn ratio of 2, a small amount of Co₃O₄ spinel emerged. After reduction, the catalysts were composed of fcc Co and ZnO. In aqueous-phase reforming (APR) of ethylene glycol, it is found that the intrinsic activity and selectivity to H₂ increase with the increment of the ZnO content. H₂ selectivities over the Co/ZnO catalysts ranged from 52% to 89%, which are substantially higher than that of the Raney Ni catalyst at similar conversion. Moreover, the Co/ZnO catalysts produced much less CO in the product gas. With the aid of literature works as well as additional experiments on APR of acetic acid, methanol, and ethanol, the reaction pathways of ethylene glycol in the presence of water on the Co/ZnO catalysts were discussed.

Graphical abstract

Research highlights

▶ Co/ZnO catalysts were prepared by the coprecipitation method. ▶ They exhibit high intrinsic activity and H₂ selectivity in APR of ethylene glycol. ▶ The reaction pathways are discussed.

Introduction

Approximately 80% of the present world energy demand comes from fossil fuels [1], which are exhaustible and cause serious environmental problems. Recently, Dumesic and coworkers demonstrated the new process of aqueous-phase reforming (APR) of biomass-derived polyols such as ethylene glycol, glycerol, and sorbitol to H₂ and hydrocarbons [2], [3], [4]. The APR process is operated at temperatures near 500 K, at which the water–gas shift (WGS) reaction is thermodynamically favored, making it possible to generate H₂ and hydrocarbons in a single reactor with trace amount of CO [5]. This process is energy-efficient and green-house gas-neutral, thus opening a new opportunity for the utilization of readily available renewable biomass.

Catalysts that have been studied in the APR of ethylene glycol include Pt-based catalysts [2], [6], [7], [8], [9], [10], [11], [12], [13], SiO₂-supported Ni, Pd, Ru, Rh, and Ir catalysts [6], Sn-modified Raney Ni [3], [8], [14], [15], Ni/Al₂O₃ catalysts [8], [14], rapidly quenched skeletal Ni [16] and NiMo catalysts [17], and non-pyrophoric Ni catalyst derived from traditional Ni₅₀Al₅₀ alloy [18]. However, the APR performance of Co-based catalyst has not been explored as far as we are aware of. It is acknowledged that Co exhibits appreciable activities for C–C bond scission, WGS, and Fischer–Tropsch synthesis (FTS) among VIIIB metals [6], [19], so the Co-based catalyst is anticipated to be promising for the APR process.

It has been shown that the Co-based catalysts are efficient in steam reforming (SR) of ethanol [20]. Homs and coworkers have prepared Co catalysts by impregnating Co₂(CO)₈ on a series of supports, and found that the ZnO-supported Co catalyst exhibited the best catalytic performance in SR of ethanol [21]. Motivated by their work, we prepared Co/ZnO catalysts with different Co/Zn ratios by the coprecipitation method using less hazardous cobalt nitrate. Their catalytic behaviors in APR of ethylene glycol were investigated and correlated with the characterization results. The reaction pathways of ethylene glycol on the Co/ZnO catalysts in the presence of water were discussed with the aid of additional experiments on APR of acetic acid, methanol, and ethanol.

Section snippets

Catalyst preparation

The Co/ZnO catalysts with four different Co/Zn molar ratios were prepared by the coprecipitation method. An aqueous solution fixed at 0.4 M containing a mixture of Zn(NO₃)₂ and Co(NO₃)₂ was added drop by drop to an aqueous solution of Na₂CO₃ (0.4 M) as the precipitant at 333 K under stirring. After being aged at 333 K for 2 h, the solid was filtered, washed with deionized water to neutrality, dried at 373 K overnight, and then calcined at 723 K for 4 h at a heating rate of 10 K min⁻¹ in static air. The

Physicochemical properties

Table 1 lists the bulk compositions and BET surface areas of the Co/ZnO samples. It is found that the experimental Co/Zn molar ratios always exceed the nominal values, suggesting that zinc cations are more reluctant to precipitate than cobalt cations under the present preparation conditions. With the increment of the Co/Zn ratio, the experimental ratios approach the nominal values. For the calcined Co/ZnO samples, the BET surface area increases slightly from 41 to 47 m² g⁻¹ with the increment of

Conclusion

In APR of ethylene glycol, the Co/ZnO catalysts prepared by the coprecipitation method could exhibit higher intrinsic activity and H₂ selectivity than the Raney Ni catalyst. Moreover, the Co/ZnO catalysts produced much less CO, which is especially desirable for fuel cell applications, demonstrating the potential of cobalt as an effective component in formulating a H₂-specific catalyst for APR of ethylene glycol. Future catalyst development work should focus on the preparation of Co/ZnO

Acknowledgments

This work was supported by the National Basic Research Program of China (2006CB202502), the NSF of China (20673025, J0730419, 20803011), the Program of New Century Excellent Talents in Universities (NCET-08-0126), the Science & Technology Commission of Shanghai Municipality (10JC1401800, 08DZ2270500), and the State Key Laboratory of Catalytic Materials and Reaction Engineering (RIPP, SINOPEC).

References (40)

D. Das et al.
Int. J. Hydrogen Energy
(2001)
R.R. Davda et al.
Appl. Catal. B: Environ.
(2005)
R.R. Davda et al.
Appl. Catal. B: Environ.
(2003)
J.W. Shabaker et al.
J. Catal.
(2003)
X.H. Liu et al.
Catal. Commun.
(2008)
O. Skoplyak et al.
Catal. Today
(2009)
J.W. Shabaker et al.
J. Catal.
(2004)
J.W. Shabaker et al.
J. Catal.
(2005)
F.Z. Xie et al.
J. Catal.
(2006)
J. Llorca et al.
J. Catal.
(2002)

R.C. Reuel et al.

J. Catal.

(1984)

J. Llorca et al.

Appl. Catal. B: Environ.

(2003)

C. Tang et al.

Thermochim. Acta

(2008)

Y. Zhang et al.

J. Catal.

(1999)

N.N. Madikizela-Mnqanqeni et al.

J. Mol. Catal. A: Chem.

(2005)

M. Haneda et al.

Appl. Catal. B: Environ.

(2003)

Y. Pei et al.

J. Catal.

(2007)

B. Ernst et al.

Appl. Catal. A: Gen.

(1999)

R.A. Lemons

J. Power Sources

(1990)

M.A. Vannice

J. Catal.

(1975)

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Aqueous-phase reforming of ethylene glycol on Co/ZnO catalysts prepared by the coprecipitation method

Abstract

Graphical abstract

Research highlights

Introduction

Section snippets

Catalyst preparation

Physicochemical properties

Conclusion

Acknowledgments

Int. J. Hydrogen Energy

Appl. Catal. B: Environ.

Appl. Catal. B: Environ.

J. Catal.

Catal. Commun.

Catal. Today

J. Catal.

J. Catal.

J. Catal.

J. Catal.

J. Catal.

Appl. Catal. B: Environ.

Thermochim. Acta

J. Catal.

J. Mol. Catal. A: Chem.

Appl. Catal. B: Environ.

J. Catal.

Appl. Catal. A: Gen.

J. Power Sources

J. Catal.