Evolution of the Active Phase of CoMo/Al2O3 Catalysts under Industrial Conditions: a High-Pressure MES Study

The behavior of CoMo/Al2O3 catalysts sulfided in H2S/H2 gas mixture, under industrial conditions, was investigated using Mossbauer emission spectroscopy (MES). An intermediate Co‐Mo phase is formed after increasing the sulfidation pressure to 4 MPa, favoring the Co‐Mo‐S phase formation. An increase in the quadrupole splitting value of the Co‐sulfide species after treatment at 573 K is proposed as a prerequisite for the formation of ideal Co‐Mo‐S structures.