(A) Thermal decomposition of hydrocarbons in the absence of oxygen
The thermal decomposition of hydrocarbon is carried out in closed systems, and two major processes belong to this category: the thermal black and the acetylene black process. The thermal black process is discontinuous and runs cyclically in two separate process steps. In the first step, the energy for the thermal decomposition of the feedstock is generated by the complete combustion of fuel like natural gas or oil without formation of any carbon black. In the second step, the feedstock is injected in the hot reactor and the thermal decomposition and carbon black formation occur. The acetylene black process is based on the exothermic decomposition of acetylene gas into acetylene black and hydrogen occurring above ca. 800 °C. The process reaction is initialized by burning acetylene gas with air. Once the reaction temperature is reached, the acetylene decomposition to carbon black and hydrogen is self-sustaining and runs continuously.