TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Process: The catalyst precursor is formed by co-precipitating metal salt solutions, preferably nitrate, chlorides or carboxylate, preferably acetate of at least two metals of cobalt, manganese, molybdenum, aluminum or magnesium. The co-precipitation of the metal salts takes place using an alkaline solution of an acid solution of the metal salts. The high temperature calcination takes place at 800-1100 degrees C, preferably 900-1050 degrees C. The conversion of the hydrocarbon in a fluidized bed takes place under the continuous or discontinuous addition of catalyst, optionally using a carrier gas, preferably nitrogen or hydrogen, and under continuous discharge of carbon nanotubes from the fluidized bed. Preferred Components: The carbon nanotubes contain at most 7, preferably 5 wt.% of impurities, preferably metals or metal compounds, preferably metal oxides. The carbon nanotubes are in the form of multi-walled carbon nanotubes, preferably based on nested graphite tubes, or rolled-up, multi-layer graphene layers. At least 95 wt.% of the agglomerate particle has outer diameter of 20-6000, preferably 100-1500 mu m. The agglomerate exhibits a bulk density of 20-250, preferably 50-150 kg/m3, according to EN ISO 60. The carbon nanotubes in the bulky yarn are interwoven to each other and are essentially non-aligned straight with each other. The bulked yarn made from carbon nanotubes has a diameter of 0.1-20, preferably 0.18-3 mu m. Less than 30, preferably 10% of the agglomerate, except carbon nanotube bundles in the form of bulked yarn, exhibits other structural bundle forms of carbon nanotubes, preferably a series of carbon nanotube bundle in: worsted structure, bird's nest structure, an open network structure or the form of parallel-oriented fibrils. EXAMPLE - A solution of magnesium nitrate hexahydrate (306 g) in water (0.35 l) was mixed with a solution of aluminum nitrate nanohydrate (360 g) in water (0.351 g). Then, manganese nitrate tetrahydrate (170 g) and cobalt nitrate hexahydrate (194 g) dissolved in water (0.51 g) was added and the mixture was stirred for 30 minutes and pH was set to about 2 by the addition of nitric acid. A stream of the obtained solution was mixed with sodium hydroxide (20.6 wt.%) and the obtained suspension was added into water (51 g). The unusual solid material was removed from the suspension and washed. The washed solid was then dried within first eight hours from room temperature to 160 degrees C. The solid was calcined for 3 hours at 1000 degrees C in the presence of air and cooled for 24 hours. The catalyst material was then post-oxidized for 7 days at room temperature to obtain catalyst material (109 g). The obtained catalyst (18 g) was heated at 700 degrees C under nitrogen. Further feed gas mixture of ethylene and nitrogen was added and reacted for 31 minutes to obtain carbon nanotube agglomerate.