Chen Changpin

THE SEPERATION AND RECOVERY OF HYDROGEN FROM THE RECYCLING GAS IN AMMONIA PRODUCTION BY MEANS OF LANTHANUM-RICH MISCHMETAL NICKEL HYDRIDE BEDS

The seperation and recovery of hydrogen by means of a MlNi5 (Ml: La-rich mischmetal) beds were studied. The influence of the impurity gas components (O2, H2O, N2, Ar, CH4 and NH3 etc) on the hydrogen absorption capacity, hydriding and dehydriding kinetics and cycling ageing stability of the beds was investigated for both stagnent gases and continuously flowing gas streams. In small reactors, at first artificially made gas mixtures and finally the actual recycling gas from ammonia production were tested. In the presence of trace ammonia (<100ppm) in recycling gas stream, the efficiency of recovery amounted to 85 - 93% and the purity of the product hydrogen was around 99.9%. When ammonia amounted to 2.5%, the efficiency of recovery decreased to 81 -86%. The hydrogen absorption capacity of the alloy bed remained unchanged after cycling 50 times, indicating the stability of the alloy satisfactory.