| Popis: |
The intermetallic phases NiAl 3 , Ni 2 Al 3 , (Ni 1−x Fe x ) 2 Al 3 , FeAl 3 and Fe 2 Al 5 , are obtained as single phase, then they are used to prepare Raney catalysts. Composition, structure and crystallite size of Ni, Fe and (NiFe) catalysts are determined by chemical analysis and X-Ray diffraction. For Raney Ni, the composition results show the residual Al content to be higher in the catalysts proceeding from the intermetallics with the lower Al content. For the Raney (Ni,Fe) catalyst, the Fe/Ni ratio is of the same order than in the (Ni 1−x Fe x ) 2 Al 3 master alloy. From the structure results, a second phase, likely NiAl, is found beside fcc Ni in the catalysts with high residual Al content. The crystallite size of the various catalysts is in the range 3–15 nm; the surface area obeys a linear relationship versus the reciprocal of crystallite size. |
