Radiolysis of mixtures of carbon dioxide and hydrogen

Abstract The self‐radiolysis of CO 2 in excess tritium ( 3 H 2 ) has been studied at pressures of 0.1 to 1.0 atm, temperatures of −80° to +100°C, and in the presence of added H 2 O, He, or Ar. The primary products of decomposition are CO and 3 H 2 O. Secondary products are C 3 H 4 , C 2 3 H 4 , and a white polymer. The rates of disappearance of CO 2 and formation of products and G ‐;values were measured. The disappearance of CO 2 initially obeys first‐order kinetics, then slows down with time at a rate depending upon the initial pressure of 3 H 2 . The initial rates are proportional to pressures of CO 2 and 3 H 2 . They are independent of temperature, decreased by addition of H 2 O vapor, and increased by addition of He or Ar. The proposed mechanism of decomposition of CO 2 and formation of products involves ionization of CO 2 followed by dissociative recombination forming CO and O. Then the O reacts with a hydrogen‐containing species forming OH and H 2 O, and a back reaction forms CO 2 from CO and OH.