Gamma irradiation of hydrocarbon-liquid nitrogen systems and the synthesis of ammonia

The 60Co-gamma radiolysis of hydrocarbons (HC)-liquid N2 mixtures at 770K and 1.8 atm of pressure was investigated. Batch irradiation studies of methane, ethane, and ethylene and semibatch studies of methane were made in the presence and absence of transition metal oxide catalysts. In noncatalyzed systems, the effects of varying the radiation dose, total dose, solute feed rate and concentration and liquid N2 volume were investigated. NH3 was found to be the major N-containing product in the alkane solute system. N2 and HC radical addition was found to be the predominate initial reaction for nitrogeneous product formation. Results of scavenger studies indicate that excited N2 played a lesser role in precursor formation. All product yields were found to be dependent upon the H-containing species availability in the liquid N2 solution. Production rates were limited by HC solubility. The use of the transition metal oxide supported catalyst greatly increased product formation in all systems. Product yields were found to be dependent upon the available catalyst surface area, metal loading, and reduction techniques for each metal examined. As evidenced by the radiation lag time studies, the stability of the N2 precursors on the catalyst surface was believed to be a significant factor in reaction enhancement. Energy transfer from the catalyst to the absorbates was examined and could not be ruled out