Oxidative coupling of methane catalyzed by Li, Na and Mg doped BaSrTiO 3 Z. Fakhroueian, F. Farzaneh * , N. Afrookhteh Department of Chemistry, University of Alzahra, Vanak, Tehran, Iran National Petrochemical Company Research and Technology Company (NPC-RT), Iran Received 25 September 2007; received in revised form 11 February 2008; accepted 12 February 2008 Available online 7 March 2008 Abstract The XBaSrTiO 3 (X = Li, Na, Mg) with perovskite structure was prepared by impregnation of LiCl, NaCl or MgCl 2 solution on BaSr- TiO 3 (BST) surface. The products were characterized with XRD, SEM, UV, FT-IR and Raman spectroscopy. Determination of band gap, conduction and basicity of the prepared catalysts revealed that NaBST exhibits the lowest band gap and the most conduction and basicity. The catalytic performances of XBSTs for the oxidative coupling of methane (OCM) in a tubular continuous flow reactor were evaluated. The NaBST showed the maximum catalytic effect on methane conversion (47%), C 2+ selectivity (51%) and ethylene yield (24%) at the temperature of 800 °C. Ó 2008 Elsevier Ltd. All rights reserved. Keywords: BaSrTiO 3 ; Oxidative coupling of methane; Doping; Perovskite 1. Introduction Based on the world annual total production, ethylene seems to be the most important base organic chemical in petrochemical industries [1]. Since 1982, there has been much research on the oxidative coupling of methane (OCM) process [2]. Direct catalytic conversion of methane to C 2 and higher hydrocarbons by OCM is considered a potential route for the production of useful chemicals and fuels from abundant natural gas [3]. The progress of OCM reaction depends on temperature, chemical catalyst and composition of reaction mixture. OCM takes place at high temperature (900 °C) and may be performed by two modes: cyclic mode with the alternate feeding of reactions (methane and oxidants) and co-feed mode with the simultaneous feeding of reactants [3,4]. Innumerable catalysts have been studied and found to be effective in this complex heterogeneous–homogeneous process. They are mostly bi or multicomponent mixed or supported metal oxides containing components with basic properties such as oxides of alkali metals, alkaline earth metals, and rare earth metals [5]. Long and co-workers have found that CH 4 conversion and C 2+ selectivity were high over SrF 2 /Nd 2 O 3 catalyst than over pure Nd 2 O 3 for OCM reaction [6]. They found that properties such as sur- face basicity and conductivity are important factors for OCM catalysts [6]. Dedov and co-workers studied on the rare earth metal oxides or their mixture for OCM [7]. They found that such mixture reveals good efficiency in the OCM [7]. La 0.2 Sr 0.8 CoO 3 (LSC), SrCoFe 0.2 O 3 (SCF), Y 2 O 3 doped Bi 2 O 3 and Bi 1.5 Y 0.3 O 3r (BYS) were tested for OCM by Lin and his co-workers [8]. Lansford et al. worked on OCM over oxide-supported sodium–manganese catalysts [9]. It was also found that Mn/Na 2 WO 4 /SiO 2 and Mn/Na 2 WO 4 /MgO were active catalysts for OCM reactions [10,11]. MnO x with lowest band gap and highest electrical conductivity on Na 2 WO 4 / SiO 2 showed the best catalytic performance [12] with 20% CH 4 conversion and 16% yield. Ji et al. [13] investigated 0016-2361/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.fuel.2008.02.010 * Corresponding author. Address: Department of Chemistry, University of Alzahra, Vanak, Tehran, Iran. Tel.: +98 21 88258977; fax: +98 21 66495291. E-mail address: faezeh_farzaneh@yahoo.com (F. Farzaneh). www.fuelfirst.com Available online at www.sciencedirect.com Fuel 87 (2008) 2512–2516