Effect of pressure on radiolysis of hydrogen-carbon monoxide mixtures in unpacked metal vessels

Formation of hydrocarbon products in the gamma radiolysis of 3:1 hydrogen-carbon monoxide mixtures in unpacked nickel and stainless steel vessels has been investigated at room temperature over the pressure range 149 to 3242 torr. Yields of all products were less than 0.05 G units at all pressures. The predominant products were ethane and propane with G values of 0.042 and 0.0062 in nickel vessels at 149 torr. Smaller yields of ethylene, i-butane, n-butane, propylene, i-pentane, and n-pentane were found. In the nickel vessels, alkane yields dropped sharply with increasing pressure, but alkene yields were only slightly pressure dependent. It is concluded that the major reaction pathways to ethane and propane involve surface catalysis, but a very low efficiency homogeneous reaction (G values in the range of 10-4) producing roughly similar yields of alkanes and alkenes may also exist. (author)