TEXTURE OF RANEY NI CATALYSTS - AL-LEACHING OUT OF RAPIDLY SOLIDIFIED NI2AL3 ALLOYS

Raney catalysts are prepared by removing Al out of Ni-Al alloys in boiling NaOH. The evolution of the microcrystallized Ni//2Al//3 structure during Al-leaching out is essentially studied by transmission electron microscopy. The different phases of the precursor microcrystallized alloys are attacked selectively. Moreover, Al-leaching out of Ni//2Al//3 occurs step by step. The Ni crystallites' orientation is directly related to the orientation of precursor alloys. An intermediate phase of Ni//2Al type was observed. AES experiments were also performed before and after Al-leaching out of undoped and Cr-doped alloys.