Nickel catalyst nitrogen adsorption

Aluminium dissolves with H2 evolution, and this hydrogen remains chemisorbed on nickel, presumably in a dissociated form. Raney nickel catalysts are often doped with other metals in order to improve the catalytic activity the selectivity decreases in the order. Mo > Cr > Fe > Cu > Co. These metals are fused with the Ni-Al alloy and remain on the final catalyst, probably as oxides. It is believed that the role of the doping metals is to strengthen the selective adsorption of nitrogenous substrates. 

Figure 6.2 Nickel activity and B5 sites [415], Ni/Al203 catalysts (including K-promoted catalysts). B5 sites measured by nitrogen adsorption [415]. Reproduced wilh the permission of Elsevier.

Nitrogen and krypton physisorption measurements at 77 K and hydrogen chemisorption measurements at 293 K were carried out with a Belsorp 28SA automatic adsorption apparatus in order to obtain BET surface area and the number of surface nickel atoms, respectively. The structure of catalysts was determined by X-ray diffraction using Cu radiation. 

---