Analysis of a direct methane conversion to high molecular weight hydrocarbons

Abstract

Methane conversion to heavier hydrocarbons was studied using electrical furnaces and a plasma apparatus. The experiments were performed with pure methane for the electrical furnace experiments while pure methane and additions such as hydrogen and ethane were studied for the plasma apparatus. A variety of tubes was tested as reactor tubes for the electrical furnaces apparatus, and a silicon carbide tube was used as a reactor tube in the experiments performed. The operating pressure for the electrical furnace was around one atmosphere. In the plasma apparatus, the reactants were mixed with plasma gas downstream of the plasma and were shell quenched. The plasma experiments were performed at different flow rates and conditions. The experiments were done at currents of 150 to 800 A, at quenching positions of 5, 6, 7, 8" down stream. The operating pressure of the plasma tube reactor was around 7 psig. The voltage varied from 30 to 60 V. It was found that the selectivity of acetylene can be increased to more than 0.9 by adding hydrogen, operating at high average temperatures of mixing, and quenching very fast. Furthermore, ethane was formed when hydrogen was added to the methane in the feed which indicates that hydrogen increases the selectivity of ethane. The selectivity of ethylene was low in all the experiments and it was around 0.06. The addition of ethane showed good results compared to that of pure methane.