Interactions of supported nickel and nickel oxide catalysts with methane and steam at high temperatures Pooya Azadi a , Junichiro Otomo b,n , Hiroyuki Hatano c , Yoshito Oshima b , Ramin Farnood a a Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College St., Toronto, Ontario, Canada M5S 3E5 b Department of Environment Systems, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8563, Japan c National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan article info Article history: Received 11 November 2010 Received in revised form 31 May 2011 Accepted 1 June 2011 Available online 15 June 2011 Keywords: Catalysis Catalyst support Energy Reaction engineering Chemical looping combustion Steam reforming abstract The catalytic performance of cermets made of 10% nickel or nickel oxide supported on YSZ (yttria- stabilized zirconia) for chemical looping combustion (CLC) and steam reforming (SR) of methane at 700 1C is investigated. Steam reforming of methane over the reduced catalyst resulted in a syngas containing more than 70% hydrogen and about 15% carbon monoxide. Chemical looping combustion of methane with insufficient lattice oxygen could potentially lead to 40–65% hydrogen rich gas products. Prolonged induction period (e.g. 30–80 min) in reduction of nickel oxide by methane has been observed in the presence of steam. The span of induction period increases by increasing steam partial pressure. It is hypothesized that the delayed reduction of nickel oxide is related to the retarding effect of steam on autocatalytic reactions of methane and hydrogen with lattice oxygen of nickel oxide and the subsequent reforming reactions. & 2011 Elsevier Ltd. All rights reserved. 1. Introduction The catalytic processes for hydrogen and synthesis gas pro- duction are among the most important processes in providing high quality fuels and food. Hydrogen is used in ammonia synthesis, fuel cells, hydrotreating and hydrogenation processes, while methanol production and Fischer–Tropsch synthesis of liquid fuels require syngas. Currently, due to low production costs and availability, hydrogen is commonly produced by the steam reforming (SR) of hydrocarbons; such as methane and naphtha in the presence of heterogeneous metal catalysts. Industrial hydro- gen production from hydrocarbons involves desulfurization, pre- reformer (for heavy hydrocarbons), primary and secondary refor- mers, high and low temperature water gas-shift reactions and methanation. Typical operating temperature for SR processes ranges from 600 to 1100 1C. Because of its high catalytic activity and relatively low price, nickel is the preferred metal for catalyz- ing the steam reforming reactions. In the pre-reformer and primary steam reforming steps, usually Ni/MgO (naphta), Ni/ MgAl 2 O 4 and Ni/CaAl 2 O 4 are utilized to catalyze the reactions while Ni/CaAl 2 O 4 and Ni/a-Al 2 O 3 are commonly used for the secondary reformer. In order to maximize hydrogen yield and to prevent carbon deposition on the catalyst, the reformer is oper- ated at a higher steam-to-carbon ratio than the stoichiometric value. Once CO and H 2 are produced, the equilibrium concentra- tions of all species (i.e. CO, H 2 , CO 2 , CH 4 and H 2 O) are formed rapidly. Additional hydrogen can be obtained through water gas- shift reaction at lower temperatures. Autothermal reforming (ATR) and catalytic partial oxidation (CPO) are alternative approaches for syngas and hydrogen pro- duction. ATR utilizes both steam and oxygen and results in a syngas with slightly lower H 2 /CO ratio compared to that of steam reforming. CPO solely uses oxygen and leads to formation of a low H 2 /CO ratio gas. The following reactions are involved in ATR and CPO. Autothermal reforming: CH 4 þ 3/2O 2 -CO þ 2H 2 O (1) CH 4 þ H 2 O-CO þ 3H 2 (2) CO þ H 2 O-CO 2 þ H 2 (3) Catalytic partial oxidation: CH 4 þ 1/2O 2 -CO þ 2H 2 (4) As an alternative to these conventional processes, a new process called chemical looping is under development that can be applied to hydrocarbons for total or partial combustion. In this Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/ces Chemical Engineering Science 0009-2509/$ - see front matter & 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.ces.2011.06.002 n Corresponding author. Tel.: þ81 4 7136 4714; fax: þ81 4 7136 4715. E-mail address: otomo@k.u-tokyo.ac.jp (J. Otomo). Chemical Engineering Science 66 (2011) 4196–4202