New insights into the effect of nitrogen incorporation in Mo: catalytic hydrogenation vs. hydrogenolysis

The catalytic effect of nitrogen incorporation into Mo on hydrogenation (of –NO2 to –NH2 in nitrobenzene to aniline) and hydrogenolysis (of –CO in benzaldehyde to toluene) processes has been assessed. Bulk Mo was prepared by temperature programmed reduction of MoO3 (in H2 to 933 K) and β-Mo2N (confirmed by powder XRD) subsequently synthesised by Mo nitridation in N2/H2. Two intermediate samples (MoN-1 and MoN-2) with different Mo/N ratio were prepared by altering the duration (1 and 2 h) of the nitridation step. XPS analysis revealed a nitrogen surface enrichment (Mo/N = 2.2 → 0.9 from MoN-1 to β-Mo2N) relative to the bulk (Mo/N = 5.1 → 2.5). Incorporation of N did not affect morphology and each sample exhibited (by SEM analysis) aggregates (