Reaction of atomic hydrogen with carbon. [Carbon target at 30-950/sup 0/C; no unsaturated hydrocarbons detected]

A metal and glass reactor was used to study low-pressure atomic hydrogen and carbon reactions. Atomic hydrogen produced thermally was allowed to impinge on a temperature-controlled carbon target in the temperature range 30-950/sup 0/C. Unreacted hydrogen and organic reaction products were isolated on a liquid helium cold finger placed close to the carbon target and were subsequently analyzed both quantitatively and qualitatively by gas chromatography. Over the temperature range examined the major organic reaction product was CH/sub 4/ approximately equal to 90 percent, together with smaller amounts of C/sub 2/H/sub 6/ approximately equal to 9 percent and C/sub 3/H/sub 8/ approximately equal to 1 percent. No unsaturated hydrocarbons were detected. Contrary to the results of previous studies on the reaction, the formation of hydrocarbons did not reach a maximum at about 550/sup 0/C, but showed a continuous increase with temperature. The methane yield temperature dependence showed three distinct phases and activation energies were obtained. Upper and lower limits of 17 percent and 0.6 percent were determined for the room temperature conversion of atomic hydrogen to methane at the carbon target. At 950/sup 0/C these values were threefold larger.