TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The length to diameter ratio of the carbon nanotubes is at least 5, preferably at least 50. The powder comprises maximum 7 wt.%, preferably 5 wt.% of impurities made of metals or metal compounds, preferably metal oxides. The impurities comprise metals or metal compounds of the transition metal, preferably the group VII and group VIII elements of the periodic system, or the alkaline metal or the alkaline earth metal or silicon or silicon oxide. The metals or metal compounds comprise aluminum, magnesium, titanium, zirconium, calcium, iron, nickel, manganese, molybdenum or cobalt. The powder comprises maximum 7 wt.%, preferably 1 wt.% of pyrolytically deposited carbon. The carbon nanotube powder is present as agglomerate, where at least 95 wt.% of the agglomerate portion has an outer diameter of 5-10000 mu m, preferably 50-3000 mu m. The bulk density (according to EN ISO 60) of the carbon nanotube powder is 20-450 kg/m3, preferably 110-250 kg/m3. The specific surface (nitrogen adsorption according to Brunauer-Emmett-Teller) is 20-1500 m2/g, preferably 90-600 m2/g. The carbon nanotubes (viewed in cross-section) exhibit a maximum outer diameter of up to 500 nm, preferably 50 nm. The average retention time of the catalyst in the reaction zone is 20-45 minutes, preferably 25-35 minutes. The catalyst comprises cobalt (45-55 mol.%) and manganese (55-45 mol.%). Preferred Method: The carbon nanotube powder is deagglomerated by grinding or dispersing under energy input. EXAMPLE - A transition metal catalyst was produced by mixing magnesium nitrate hexahydrate (0.306 kg) in water (0.35 liter) with a solution of aluminum nitrate nonahydrate in water (0.35 liter) and subsequently adding manganese nitrate tetrahydrate (0.17 g) and cobalt nitrate hexahydrate (0.194 kg). Then a reactor was inertized with nitrogen and heated at 650 degrees C. Then the reactor was added with the catalyst (24 g). Then a mixture of ethane and nitrogen with a ratio of 90:10 as educt gas was added to the reactor. The retention time of the catalyst in the reaction zone was 33 minutes. Finally 35.3 g of carbon nanotube powder per gram of used catalyst was obtained.