Synthesis of a catalyst system to a production method of carbon nanotubes multiwall

Process for the synthesis of a catalyst system for the selective conversion of hydrocarbons ennanotubos carbon and hydrogen multiple walls, said catalyst comprising a compound deformula: CoFe2O4 (Al2O3) w where w £ 32 £ 4.5 the method comprising the steps of: - synthesizing a hydroxide precursor of the formula CoFe2 (OH) 8 (Al (OH) 3) q, wherein q is entre9 and 64, by reaction between compounds of cobalt, iron and aluminum led out according SomeProcedure selected from the group consisting of impregnation, coprecipitation, sol-gel ycomplejacion citrate; - heat treating said precursor hydroxide to form the compound.