Effect of infrared laser radiation on gas-phase pyrolysis of ethane

Pyrolysis of hydrocarbons is widely used for the production of light olefins. The pyrolytic processes are energy-consuming, proceeding at high wall reactor temperature and producing large amounts of undesired carbonaceous side-products. There is a demand for the search of lower temperature regimes together with the reduction of side products at high conversion efficiencies. The objective of our research is to decrease the temperature of walls of the pyrolytic reactor for the ethane thermal decomposition by CO2-laser radiation. Gas-phase laser induced pyrolysis of ethane was studied in a continuous flow tubular reactor. Introduction of infrared laser radiation into the pyrolysis reactor results in significant reduction of the reaction temperature threshold and noticeable increase of the ethane conversion at temperatures 870-970 K. At low-temperature range, 760-920 K, significant increase of ethane conversion was observed in the presence of ethylene comprising 5-10 % vol. of the initial gas mixture. Similar shift of temperature threshold was also observed with the increase of radiation power density. Analysis of volatile products demonstrated minor differences in the product content for both conventional and laser-induced pyrolysis, thus confirming the laser radiation function as an additional energy source without significant interference in the gas phase reactions. From practical point of view the laser induced pyrolysis opens the possibility to save energy on the account of reduced temperature. The low-temperature pyrolysis could additionally be promoted by the introduction of unsaturated hydrocarbons.