INTERACTION BETWEEN THE LANI5-TYPE INTERMETALLIC COMPOUND AND HYDROGEN-SULFIDE

H2S interaction with powdered La0.95Ce0.05Ni4.98Al0.02 has been studie d in the temperature range 293-973 K. Sorption experiments were carrie d out using a flow system with gas stream 3 vol% H2S in Ar, 1.5 vol% H 2S in Ar and 3% H2S/60% H-2/37% Ar. Structural changes and surface mor phology were studied by X-ray diffraction and scanning electron micros copy. At T = 293 K, large amounts of H2S were absorbed by the sample w ithout significant changes in its structure, corresponding to x = 4.5 for La0.95Ce0.05Ni4.98Al0.02(H2S)(x). At T = 353 K, hydrogen sulfide w as also absorbed; however, after the first 100 min of total absorption without any products in the outlet gas, 10-20% H-2 was registered (wi th regard to amount of H2S in the initial gas stream). X-ray patterns show the beginning of the formation of Ni3S2 and amorphous phase with a diffuse maximum in the range 24-32 degrees (2 theta, Cu-K-alpha). Wi th T increasing, H-2 content increases and equals 30-40% at T = 433 K and 50% at T = 773 and 973 K. According to XRD, Ni3S2. La2S3 and initi al phase are present. After prolonged testing at 773 K, LaH2 peaks app eared in X-ray patterns. Electron micrographs show large particle form ation with porous flaky sulfides distributed over them. Experimental d ata for a 3% H2S/60%/H-2/37% Ar mixture are in agreement with those de scribed above. H2S is removed from the mixture at T = 773 K while the amount of H-2 is constant. This research was carried out in connection with the problem of refining H-2 produced from natural gas containing H2S.