Improvements in carbon black and carbon black processes

摘要

Carbon black is produced by continually introducing a fluid hydrocarbon into a zone wherein an inert, elementary gas having no more than two atoms per molecule, at a pressure of at least one atmosphere, is subjected to a radio frequency, electrodeless discharge to maintain the gas in a thermal plasma state. Suitable fluid hydrocarbons are methane, ethane, ethylene, butane, butylene, and higher homologues of saturated and unsaturated hydrocarbons and fuels containing same. The gas may be helium, neon, zenon, radon, argon, nitrogen, hydrogen. In the Figure, argon is fed tangentially under positive pressure into annular space between quartz tubes 12 and 11 so that it spirals up through tube 11 and remains in close proximity to the inner walls. Radio frequency current, e.g. 3 to 5 megacycles for monatoric gases from a generator is supplied to cylindrical copper coil 24 which may be hollow to circulate coolant therethrough. Metal tube 14, connected in air-tight fashion with hydrocarbon feed line 16, is raised into reaction zone 10 wherein it is heated by the high-frequency field and creates a localized plasma which establishes a thermal plasma. Tube 14 is then lowered. Alternatively, the plasma may be started by a tantalum, or other metal, wire or a carbon rod, and withdrawn after initiation. Fluid hydrocarbon is fed through tube 14 at say 39 mm./sec. into the plasma zone, wherein the temperature is at least 8000 DEG K. The carbon black may be collected by directing exhaust gases and produce carbon through a collection system, e.g. pyrex cyclones and bag filter, by an exhaust fan. The carbon blacks are characterized by small particle sizes, with a small, average number of crystallites per particle, and are useful as pigments or fillers.