Cleaner alternative liquid fuels derived from the hydrodesulfurization of waste tire pyrolysis oil

• Hydrodesulfurization (HDS) could be applied for waste tire pyrolysis oil (WTPO).
• HDS of WTPO catalyzed by NiMo catalyst reached a sulfur removal of 87.8%.
• High catalyst content, H2 pressure, temperature and time increased level of HDS.
• HDS improved color and slightly increased heating value and saturation of WTPO.

Waste tires are attractive sources for alternative energy due to their long hydrocarbon chains with a high heating value. However, the condensed (volatile portion) pyrolysis oil derived from waste tires contains a relatively large level of sulfur compounds (1.15 wt%), which is not appropriate for use in combustion engines. Therefore, this research aimed to improve the waste tire pyrolysis oil (WTPO) via hydrodesulfurization (HDS) catalyzed by molybdenum (Mo), nickel–Mo (NiMo) or cobalt–Mo supported on alumina (γ-Al2O3). The maximum % sulfur removal (87.8%) was achieved when the reaction was performed at 250 °C for 30 min using a 2 wt% NiMo/γ-Al2O3 catalyst loading based on the WTPO content and 20 bar initial hydrogen pressure. The amount of sulfurous compounds in the waste tire pyrolysis oil was determined using gas chromatography spectroscopy equipped with a flame photometric detector (GC–FPD). The HDS of the WTPO was effective to reduce the sulfurous compounds, especially thiophene and its derivatives. The results from the simulated distillation gas chromatography (GC–SIMDIS) showed that the hydrodesulfurized WTPO (HDS-WTPO) was mainly composed of a light naphtha fraction (ca. 69%). The heating value of the HDS-WTPO (44 MJ/kg) was similar to those for commercial diesel (45 MJ/kg) and gasoline (gasohol) fuels (47 MJ/kg).

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