Oxidative coupling of methane over (Ca +2 +Zr +4 ) modified with Na + Farideh Piri* 1 , Mohammad Yosefi 2 , Nahid Dayyani 1 , Narges Afroukhteh 2 1 Department of Chemistry, Faculty of Science, Zanjan University, Km. 6 Tabriz Road, P.O.Box 45195-313, Zanjan, (IRAN) 2 Gas Conversion Department, Faculty of Petrochemical, Iran Polymer and Petrochemical Institute, Tehran, (IRAN) E-mail : farideh_piri@yahoo.com Received: 2 nd October, 2009 ; Accepted: 12 th October, 2009 Full Paper Materials Science MSAIJ, 5(4), 2009 [360-363] An Indian Journal Trade Science Inc. Volume 5 Issue 4 December 2009 Materials Science OCM; Methane; Oxidative coupling of methane; Catalysts; Ethane; Ethene. KEYWORDS ABSTRACT Oxidative coupling of methane was carried out over various metal oxide catalysts (CaO + ZrO 4 ) modified with NaCl, NaI and NaOH and the catalytic performance of the catalysts was examined. These catalyst, which was pre- pared by sol-gel and then mixed of (Zr(OH) 4 +Ca(OH) 2 ) with an aqueous solution of NaCl, and NaOH, was the most effective for the formation of ethene and ethane among all the catalysts tested in this study. The results shows that the surface concentration of Na + species on each series of cata- lysts are related to electronegativity of counter ion with Na + .  2009 Trade Science Inc. - INDIA INTRODUCTION Direct catalytic conversion of methane to ethane and ethene by oxidative coupling is considered to be a promising route for the production of useful chemi- cals from abundant natural gas. It is well known that basic metal oxides such as MgO, Sm 2 O 3 , La 2 O 3 , etc. are effective catalysts for the oxidative coupling of methane [1-3] . The modification of the basic metal ox- ides with alkali ions (such as Li + and Na + ) improves the catalytic performance of the metal oxides for the oxidative coupling of methane, i.e., the addition of alkali ions into the metal oxides brings about the sup- pression of total oxidation of methane and then the improvement of selectivities to ethane and ethene [4- 8] . Although the Li + and Na + added metal oxide cata- lysts are often studied on the oxidative coupling of methane, the counter ions of Na + effect of the cata- lysts is one of the problems to be solved. There for, the counter ions effect of the Na + added catalyst is believed to be caused by the bond power between Na + and anion. EXPERIMENTAL Catalysts (Zr(OH) 4 +Ca(OH) 2 ) was prepared by using an aqueous solution of CaCO 3 and ZrOCl 2 and NaOH or NaCl and or NaI solution. The precipitate was washed with water and mixed thoroughly with an aqueous solu- tion of Na + . The Na + added sample was dried up at 373K and calcined at 1073K for 5h in air. The catalyst thus prepared is denoted as [(ZrO 2 +CaO 2 ) Na + ].