TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: (I) Is obtained by thermal treatment of (II) (preferably CoFe2(OH)8(Al(OH)3)32 or CoFe2(OH)8(Al(OH)3)64), where p is 6.5-9 (preferably 7-8.5) and q is 3-128 (preferably 9-64). The aluminum hydroxide is gibbsite (preferred) or bayerite. The specific surface of the gibbsite is 8-20 m2/g. The metallic solution comprises cobalt acetate, cobalt nitrate, nickel acetate, nickel nitrate, iron acetate or iron nitrate. The cobalt or nickel acetate is selected for (Co/Ni)/(Co/Ni)+Fe ratio of 0.30-0.40 and cobalt nitrate is selected for the Co/Co+Fe ratio of 0.30-0.75, where Co is cobalt, Ni is nickel and Fe is iron. The catalyst support particle size as determined by X-ray diffraction technique (when using the gibbsite variety of aluminum hydroxide), is 30-70 nm. The catalyst support grain size (when using the bayerite variety of aluminum hydroxide), is 20-70 microns. The carbon source is an olefin (preferably ethylene and/or propylene) and/or an alkane (methane and/or ethane), where alkane mixture is natural gas.Preferred Process: The impregnation step or the co-precipitation step, is carried out by reacting an aluminum hydroxide with metallic solutions containing soluble salts of cobalt, nickel and iron, where the impregnation is a simultaneous impregnation. The aluminum hydroxide used in the impregnation step is obtained by a calcination of aluminum hydroxide at greater than or equal to 350degreesC for 0.5-4 hours. The process of synthesizing (II) further comprises: a drying step of the impregnated or co-precipitated mixed hydroxide at 60-120degreesC for 1-4 hours; and a calcinating step of the impregnated or co-precipitated mixed hydroxide at 350-800degreesC for 10 minutes to 1 hour. The calcinating step comprises: heating in a flow of nitrogen, at 120-350degreesC at a rate of heat at 5-20degreesC per minute and remaining isothermally at the same conditions for 0.5-4 (preferably 1-2) hours; and heating in a flow of nitrogen between 450-700 (preferably 500-600)degreesC at a rate of heat at 5-20degreesC per minute and remaining isothermally for 0.5-2 hours. The reaction temperature of the contacting step of the activated catalyst, is 600-1100 (preferably 650-950)degreesC. The reaction space-time of the hydrocarbon is 0.2-0.75 g hour/mol. The spacer time of the ethylene is 0.3-0.45 g hour/mol. The spacer time of the methane is 0.2-0.45 g hour/mol. The selective conversion process is performed by a thin film catalyzed bed process, a moving bed process or a rotary kiln process. SPECIFIC COMPOUNDS - The use of 3 compounds (I) is specifically claimed, i.e. CoFe2O4(Al2O3)45 , CoFe2O4(Al2O3)16 and CoFe2O4(Al2O3)32.    EXAMPLE - No suitable example given.