Catalytic Hydrodesulfurization of a Spent Tire Pyrolysis Oil Distillate over a Ni-Mo Catalyst

This paper reports an experimental investigation into catalytic hydrodesulfurization of a spent tire pyrolysis oil distillate over a Ni-Mo catalyst. The desulfurization efficacy of the catalyst was evaluated over a range of reaction times (1-36 h), temperatures (300-375 °C), pressures (1-4 MPa), H2 concentrations (16.7-33.3% v/v), and reactive gas flow rates (H2 in N2, 45-90 mL min-1). Increasing temperature, pressure, or H2 concentration increased sulfur removal to a maximum of 99.9% w/w at 350 °C, 4 MPa, and 45 mL min-1 33.3% v/v H2. The treatment not only effectively removed sulfur but also reduced oxygenates, nitrogen-bearing compounds, and alkenes. The role of the Ni-Mo catalyst changed from adsorbing sulfur to catalyzing hydrodesulfurization as it was sulfided to Ni3S2 and MoS2. Full catalyst reduction only slightly increased the initial desulfurization activity but had an insignificant influence on subsequent sulfur removal as both the oxidized and reduced Ni and Mo forms could be sulfided to Ni3S2 and MoS2.