Ethane pyrolysis

A process of pyrolyzing ethane to produce ethyne comprising heating the ethane for a period of time within a range of 0.05 to 0.3 sec in a pyrolysis reactor having a final heating zone at a temperature in the range of 950 to 1500.degree. C., using steam as diluent gas, wherein the steam is used in a steam/ethane molar ratio of at most 3, the pyrolysis reactor being provided with a cascade of heating zones having progressively increasing temperatures in the direction of flow, and the pyrolysis reactor having a ceramic reaction zone comprising a series of juxtaposed channels grouped in rows and covering at least a part of the length of said reaction zone, parallel to its axis, the channel rows being non adjacent to one another, the reaction zone also comprising a heating zone surrounding the channel rows either on said part of the reaction zone or on a part of the length of the reaction zone when the channels cover the whole length of the reaction zone, and a cooling zone following said heating zone wherein the steam is present in a molar ratio positively influencing selectivity to ethyne production, said heating being conducted substantially solely by indirect heat exchange against surfaces of said channels in said ceramic reaction zone, and wherein said heating is conducted so that preheating to less than 950.degree. C. occurs in heating zones upstream of said final heating zone.