THERMAL EFFICIENCY OF PRODUCTION OF ACETYLENE FROM CARBON AND HYDROGEN

The effects of temperature and pressure on the heat requirements for forming acetylene from carbon and hydrogen were experimentally investigated using graphite filaments heated by timed a.c. pulses and in other experiments by condenser discharges. Acetylene is formed by the reaction of vaporized carbon and gaseous hydrogen, so the minimum energy required is that of vaporization and the associated radiation. In the thermal reaction of graphite and H2, radiation, thermal conduction, and hydrogen dissociation dissipate most of the energy if the temperature is <3600° K. By increasing the power density to high values so that the temperature exceeds 3700° K., most of the energy goes into vaporization of C and formation of acetylene. Condenser discharge heating gave the lower energy requirement, since the much shorter heating time at higher temperature lowers the energy lost by radiation and surface reactions. The limiting energy requirement for the formation of acetylene by the thermal reaction of C and H2 is in excess of 200 kcal. per mole—i.e., 4 kw.-hours per pound of acetylene. Observed experimental energy requirements approached this theoretical value. High temperature increased acetylene yield and low pressure increased product purity. © 1968, American Chemical Society. All rights reserved.