Effect of N 2 O-mediated calcination on nickel species and the catalytic activity of nickel catalysts supported on g-Al 2 O 3 in the steam reforming of glycerol Youngbo Choi a , Nam Dong Kim a , Jayeon Baek a , Wooyoung Kim b , Hee Jong Lee b , Jongheop Yi a, * a World Class University (WCU) Program of Chemical Convergence for Energy & Environment (C 2 E 2 ), School of Chemical and Biological Engineering, ICP, Seoul National University (SNU), Daehak-dong, Gwanak-gu, Seoul 151-742, Republic of Korea b GS-Caltex Corporation, R&D Center, Daejeon 305-380, Republic of Korea article info Article history: Received 5 August 2010 Received in revised form 2 December 2010 Accepted 18 December 2010 Available online 23 January 2011 Keywords: Glycerol Steam reforming N 2 O Ni/g-Al 2 O 3 Calcination abstract The steam reforming of glycerol over supported nickel catalysts is a promising and cost- effective method for producing hydrogen. The activity of nickel catalysts supported on g-Al 2 O 3 is low, primarily due to the formation of inactive nickel species during high temperature calcination in air. In order to address this problem, a Ni/g-Al 2 O 3 catalyst was prepared by calcination at 700  C in a nitrous oxide (N 2 O) environment. The N 2 O calcined catalyst showed an enhanced activity for the steam reforming of glycerol. A variety of characterization techniques (XRD, TPR, XPS and H 2 Chemisorption) confirmed that the high temperature N 2 O calcination resulted in a significant decrease in the levels of nickel aluminate. The N 2 O calcination also led to an enhancement in the amount of NiO as well as nickel ions present on the surface of the catalyst. Interestingly, compared to an air calcined catalyst, the N 2 O calcined catalyst contained larger nickel particles after reduction but the N 2 O calcined catalyst had a much larger nickel surface area and dispersion, which resulted in higher glycerol conversion and hydrogen yield. Copyright ª 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. 1. Introduction Glycerol represents a promising renewable resource for producing hydrogen [1e4], because it is a major by-product of the production of biodiesel [5] and can also be produced by fermentation [6]. Hydrogen can be catalytically produced from glycerol with high selectivity by means of the steam reforming, a well established technology [3,7e9]. In addition, the steam reforming of glycerol has many merits, such as low toxicity, ease of handling and the expected growth in the availability of glyc- erol due to the rapid expansion of biodiesel production [5,10]. Among the various supported catalysts that have been investigated for the steam reforming of glycerol, nickel-based catalysts have activities comparable to noble metal-based catalysts [7,11e14]. Moreover, the low cost and availability of nickel compared to noble metal have prompted investigations of nickel-based catalysts. One of the frequently encountered problems associated with supported nickel catalysts is the formation of catalyti- cally inactive nickel species, produced by reactions between nickel and the support [15,16]. A good case in point is the development of nickel aluminate in Ni/g-Al 2 O 3 catalysts [10,17e19]. The latter has been widely studied in the steam reforming of hydrocarbons (methane [20,21], ethanol [22,23], methanol [24] etc.) as well as glycerol [11,25]. It is well known that nickel aluminate is more difficult to reduce than nickel * Corresponding author. Tel.: þ82 2 880 7438; fax: þ82 2 885 6670. E-mail address: jyi@snu.ac.kr (J. Yi). Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy 36 (2011) 3844 e3852 0360-3199/$ e see front matter Copyright ª 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijhydene.2010.12.081