Preparation and characterization of metallic catalyst using wire arc spraying and its application in partial oxidation of methane S. Kamalifar a , S. Sharifnia a, * , M.E. Aalami-Aleagha b , M.R. Panahi b a Catalyst Research Center, Chem. Eng Dept., Razi University, Kermanshah, Iran b Mech. Eng. Dept., Razi University, Kermanshah, Iran article info Article history: Received 10 October 2009 Received in revised form 21 January 2010 Accepted 28 January 2010 Available online 14 February 2010 Keywords: Partial oxidation of methane Metallic catalyst Wire arc spraying abstract The catalyst activity over a series of new metallic catalysts prepared with wire arc spraying (WAS) method was investigated in catalytic partial oxidation of methane (CPOM) to syngas. Comparing with the conventional Ni-based catalyst, the prepared WAS catalysts exhibited significant activity in CPOM. At 850 °C, CH 4 conversion and CO selectivity for the best prepared catalyst were 48.0 and 75.2, respec- tively. Also, characterization of the WAS catalysts by BET isotherm, XRD and SEM showed that the excel- lent catalytic performance of the WAS catalysts is related to the high atomizing air pressure and particle cooling rate during the preparation process. Ó 2010 Elsevier B.V. All rights reserved. 1. Introduction Synthesis gas is industrially produced through the steam reforming of methane. This process requires too high temperatures as well as a large amount of energy input due to a highly endother- mic reaction. Alternatively, the production of synthesis gas through the partial oxidation of methane (CPOM) is preferred because the reaction is an exothermic one [1,2]. Also, the CPOM produces syn- thesis gas with H 2 /CO ratio near 2, where this ratio is suitable for the synthesis to methanol and higher hydrocarbons [2,3]. Among the various noble metal catalysts examined to date [4– 6], Rh has been reported to be the most active and stable catalyst in the CPOM. Due to the costs of Rh-based catalysts, it is clear that the development of cheaper and alternative metal-based catalysts such as Fe-, Co-, and Ni-based ones would be desirable [7–10]. Tor- niainen et al. [11] investigated monolith supported Fe and found that this metal was not successful in converting CH 4 to synthesis gas as it appeared to oxidize rapidly. Meanwhile, Ni catalysts have been widely investigated because of their lower cost and relatively high activity in the CPOM [8,12,13]. However, Mixed Ni–Fe cata- lysts supported on Al 2 O 3 have been reported to show increased stability and resistance to wards carbon deposition [14,15]. In this paper, we employed wire arc spraying (WAS) technique as a novel method for the preparation of metallic catalysts. The WAS system is a branch of thermal spraying methods that is com- mercially used to produce a wide variety of coatings [16]. Thermal spraying encompasses a group of processes that are capable for rapidly depositing of metals, ceramics, plastics, and mixtures of these materials [17]. In the WAS system, the molten droplet spray is created by forming a direct current (DC) arc between two con- sumable conductive wires of the raw material. The high tempera- ture of the arc melts, wires and an atomizing gas breaks-up the molten material on the wires tips and propels it in the form of droplets to prepared catalysts [18]. Low running cost, high spray rates and efficiency make it a good process for the preparation of catalysts. However, Rosenzweig et al. [19] was formed a porous nickel coating by using the WAS method, but so far, no report on the application of WAS method for the preparation of surfaces, with catalytic properties has been reported. The performance of the prepared metallic catalysts was tested in CPOM reaction. For comparing the performance of the WAS cat- alysts, a sample of nickel catalyst based on alumina, with the same percentage of nickel was prepared. Also, the effects of some oper- ational parameters such as spraying environment (into atmo- spheric air or cold water), and pressure of atomizing air were investigated [20]. The SEM, XRD and BET analyses were applied for the study of the structure of WAS catalysts. Although, the pres- ence of each of the elemental metals in the WAS wire (alone and together) will be affect the performance of the CPOM catalyst. But, the main purpose of this study is introducing a new type of metal catalysts, which was produced by the WAS method. 2. Experiment The metal catalysts were synthesized by the WAS method. Commercially available RIMA 410 stainless steel cored wire (D 1566-7367/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.catcom.2010.01.022 * Corresponding author. Tel.: +98 831 4274535 9 (284); fax: +98 831 4274542. E-mail address: sharif@razi.ac.ir (S. Sharifnia). Catalysis Communications 11 (2010) 689–693 Contents lists available at ScienceDirect Catalysis Communications journal homepage: www.elsevier.com/locate/catcom