Effect of EDTA on hydrotreating activity of CoMo/γ-Al₂O₃ catalyst

Abstract

γ-Al₂O₃ supported Co (0–4.5 wt%) Mo (9.0 wt%) sulfide catalysts were prepared in the presence and the absence of ethylenediaminetetraacetic acid (EDTA). The hydrodenitrogenation (HDN) activity of these catalysts was studied in the model reaction of 2,6-dimethylaniline (DMA) at 300 °C under 4 MPa. The CoMo/Al₂O₃ catalysts prepared with the EDTA showed higher HDN of DMA than those prepared without EDTA. The maximum of 36% increase in rate constant of HDN of DMA was observed over the catalyst with 3% Co prepared using EDTA. The FT-IR spectroscopy of adsorbed CO on CoMo catalysts showed that EDTA addition promoted the formation of catalytically active “CoMoS” phase as evidenced from increases in intensity of band at 2070 cm⁻¹, which is maximum for 3% Co loaded catalysts. The HDN and hydrodesulfurization (HDS) activity of 3% Co loaded catalyst prepared using EDTA was tested and compared with those catalyst prepared without EDTA in a trickle bed reactor using heavy gas oil derived from Athabasca bitumen in the temperature range 370–400 °C and 8.8 MPa. Improved HDN and HDS conversion of heavy gas oil was obtained for the catalyst prepared with EDTA.