Production of transportation fuels via hydrotreating of scrap tires pyrolysis oil

Significance of the Topic

Scrap tire pyrolysis oil (STPO) offers a sustainable route to valorize end-of-life tires by converting their carbon-rich content into feedstock for transportation fuels. Hydrotreating STPO removes unsaturated compounds, sulfur, nitrogen, and improves stability, enabling integration into existing refinery processes for gasoline, jet, diesel, and marine fuel production.

Objectives and Study Overview

This work investigates the continuous fixed-bed hydrotreating of pilot-scale STPO over a commercial Ni–Mo/Al2O3 catalyst. The objective is to identify optimal conditions (210–360 °C, 6–10 MPa, WHSV = 1 h⁻¹, H₂/Oil = 400 m³/m³) yielding fractions that meet standard fuel specifications or require minimal downstream treatment.

Methodology and Instrumentation

STPO was hydrotreated in a lab-scale tube reactor with in situ sulfidation and stabilization. Products were separated into naphtha (C₅–150 °C), kerosene (150–250 °C), diesel (250–360 °C), and residue (>360 °C). Analytical techniques included GC–FID, GC×GC–FID, GC–MS, elemental analysis (ASTM D5291, D4629, D5453), density and viscosity measurements, iodine value, total acid number, simulated distillation, micro carbon residue, and CFPP.

Key Results and Discussion

• Naphtha: Complete olefin saturation, aromatics reduced from 43 vol% to ~33 wt%, sulfur <1 mg/kg at 360 °C/10 MPa. Suitable for catalytic reforming or BTEX recovery.
• Kerosene: Aromatics decreased from 48.6 wt% to 32 vol% at 360 °C/10 MPa; sulfur <3 mg/kg; smoke point marginally below JET-A1; blending with HEFA or mild post-hydrotreatment achieves aviation specifications.
• Diesel: Saturates increased to ~66 wt%, aromatics <4 wt%, sulfur <10 mg/kg, nitrogen <6 mg/kg. Cetane index improved to ~32 but below EN 590; blending with ≥35 wt% HVO yields compliant diesel (density, viscosity, cetane, CFPP < −38 °C).
• Residue: Saturate content rose to ~67 wt%, sulfur ~9 mg/kg, negligible carbon residue. Suitable for VLSFO/ULSFO marine fuels or co-hydrocracking feed.
• Hydrogen consumption: Up to 23.6 g H₂/kg STPO at 360 °C/10 MPa, primarily for aromatic hydrogenation. Desulfurization and denitrogenation required <2.4 g H₂/kg.
• Catalyst stability: Minor coke deposition (≤5.3 wt% at 10 MPa), stable activity over 170 h TOS with higher pressure reducing coke formation.

Benefits and Practical Applications

• Transforms waste tires into drop-in fuel components, reducing landfill and emissions.
• Integrates with conventional refinery hydrotreating units, leveraging existing assets.
• Generates feedstocks for gasoline reforming, jet fuel blending, diesel blending, and marine fuel production.

Future Trends and Potential Applications

• Scale-up to commercial hydrotreaters and co-processing with FCC oils and bio-oils.
• Development of noble metal catalysts for milder, deeper dearomatization.
• Advanced process integration combining STPO upgrading with renewable HEFA/HVO blending.
• Catalyst improvements to lower hydrogen consumption and extend cycle life.

Conclusion

Hydrotreating STPO at 360 °C and 10 MPa over a Ni–Mo/Al₂O₃ catalyst successfully produces naphtha, kerosene, diesel, and fuel oil fractions meeting or convertible to commercial standards. This approach enables the valorization of scrap tires in existing refinery schemes, delivering sustainable fuel components across multiple transport sectors.

Used Instrumentation

• GC–FID (Agilent 6890 N with CARBOBOND column)
• GC×GC–FID (LECO QuadJet SD with DB-17 ms × DB-1 ms columns)
• GC–MS (Thermo DSQ II with DB-5 ms column)
• Automatic distillation (Fischer)
• Density and viscosity meters (Anton Paar SVM 3000, Callisto 100)
• Elemental analyzers (ASTM D5291, D4629, D5453)
• Simulated distillation (Trace GC Ultra with CP-SimDist)
• Micro carbon residue (Normalab NMC 420)
• Cold filter plugging point (ASTM D6371)

References

1. Straka P., Auersvald M., Vrtiška D., Kittel H., Šimáček P., Vozka P., Production of transportation fuels via hydrotreating of scrap tires pyrolysis oil. Chemical Engineering Journal 460 (2023) 141764.
2. Tire Market: Global Industry Trends, Share, Size, Growth, Opportunity and Forecast 2022-2027 (2022).
3. Senin M.S., Shahidan S., Leman A.S., Hannan N.I.R.R., Analysis of physical properties and mineralogical of pyrolysis tires rubber ash compared natural sand in concrete material. IOP Conf. Ser. Mater. Sci. Eng. 2016;012053.
4. Ucar S., Karagoz S., Ozkan A.R., Yanik J., Evaluation of two different scrap tires as hydrocarbon source by pyrolysis. Fuel 84 (2005) 1884–1892.
5. Mohajerani A., Burnett L., Smith J.V., Markovski S., Rodwell G., Rahman M.T., Kurmus H., Mirzababaei M., Arulrajah A., Horpibulsuk S., Recycling waste rubber tyres in construction materials and associated environmental considerations: a review. Resour. Conserv. Recycl. 155 (2020) 104679.
6. Cummins A.C., Global ELT Management–A global state of knowledge on regulation, management systems, impacts of recovery and (2019).
7. Chen B., Zheng D., Xu R., Leng S., Han L., Zhang Q., Liu N., Dai C., Wu B., Yu G., Disposal methods for used passenger car tires: One of the fastest growing solid wastes in China. Green Energy Environ. (2021).
8. Martínez J.D., Puy N., Murillo R., García T., Navarro M.V., Mastral A.M., Waste tyre pyrolysis–a review. Renewable Sustainable Energy Rev. 23 (2013) 179–213.
9. Williams P.T., Bottrill R.P., Sulfur-polycyclic aromatic hydrocarbons in tyre pyrolysis oil. Fuel 74 (1995) 736–742.
10. Jantaraksa N., Prasassarakich P., Reubroycharoen P., Hinchiranan N., Cleaner alternative liquid fuels derived from the hydrodesulfurization of waste tire pyrolysis oil. Energy Conversion Management 95 (2015) 424–434.
11. Dębek C., Walendziewski J., Hydrorefining of oil from pyrolysis of whole tyres for passenger cars and vans. Fuel 159 (2015) 659–665.
12. Hita I., Aguayo A.S.T., Olazar M., Azkoiti M.J., Bilbao J., Arandes J.M., Castaño P., Kinetic modeling of the hydrotreating and hydrocracking stages for upgrading Scrap Tires Pyrolysis Oil (STPO) toward high-quality fuels. Energy Fuels 29 (2015) 7542–7553.
13. Hita I., Gutiérrez A., Olazar M., Bilbao J., Arandes J.M., Castaño P., Upgrading model compounds and Scrap Tires Pyrolysis Oil (STPO) on hydrotreating NiMo catalysts with tailored supports. Fuel 145 (2015) 158–169.
14. Yun G.-N., Kim K.-D., Lee Y.-K., Hydrotreating of Waste Tire Pyrolysis Oil over Highly Dispersed Ni₂P Catalyst Supported on SBA-15. Catalysts 11 (2021) 1272.
15. Jantaraksa N., Prasassarakich P., Reubroycharoen P., Hinchiranan N., Hydrodesulfurization of waste tire pyrolysis oil for cleaner fuels. Fuel Process. Technol. 146 (2016) 1–9.
16. Choi G.-G., Oh S.-J., Kim J.-S., Non-catalytic pyrolysis of scrap tires using a newly developed two-stage pyrolyzer for the production of a pyrolysis oil with a low sulfur content. Appl. Energy 170 (2016) 140–147.
17. Miskolczi N., Angyal A., Bartha L., Valkai I., Fuels by pyrolysis of waste plastics from agricultural and packaging sectors in a pilot scale reactor. Fuel Process. Technol. 90 (2009) 1032–1040.
18. Namchot W., Jitkarnka S., Catalytic pyrolysis of waste tire using HY/MCM-41 core-shell composite. J. Anal. Appl. Pyrolysis 121 (2016) 297–306.
19. Palos R., Kekäläinen T., Duodu F., Gutiérrez A., Arandes J.M., Jänis J., Castaño P., Screening hydrotreating catalysts for the valorization of a light cycle oil/scrap tires oil blend based on a detailed product analysis. Appl. Catal. B 256 (2019) 117863.
20. Palos R., Kekäläinen T., Duodu F., Gutiérrez A., Arandes J.M., Jänis J., Castaño P., Detailed nature of tire pyrolysis oil blended with light cycle oil and its hydroprocessed products using a NiW/HY catalyst. Waste Manage. 128 (2021) 36–44.
21. Han Y., Stankovikj F., Garcia-Perez M., Co-hydrotreatment of tire pyrolysis oil and vegetable oil for the production of transportation fuels. Fuel Process. Technol. 159 (2017) 328–339.
22. Liu X.-J., Wang F., Zhai L.-L., Xu Y.-P., Xie L.-F., Duan P.-G., Hydrotreating a waste engine oil and scrap tire oil blend for production of liquid fuel. Fuel 249 (2019) 418–426.
23. Abbas-Abadi M.S., Kusenberg M., Shirazi H.M., Goshayeshi B., Van Geem K.M., Towards full recyclability of end-of-life tires: Challenges and opportunities. J. Clean. Prod. 134036 (2022).
24. Zhang G., Chen F., Zhang Y., Zhao L., Chen J., Cao L., Gao J., Xu C., Properties and utilization of waste tire pyrolysis oil: A mini review. Fuel Process. Technol. 211 (2021) 106582.
25. Okoye C.O., Jones I., Zhu M., Zhang Z., Zhang D., Manufacturing of carbon black from spent tyre pyrolysis oil–a literature review. J. Clean. Prod. 279 (2021) 123336.
26. Okoye C.O., Zhu M., Jones I., Zhang J., Zhang Z., Zhang D., An investigation into the preparation of carbon black by partial oxidation of spent tyre pyrolysis oil. Waste Manage. 137 (2022) 110–120.
27. Martínez J.D., Lapuerta M., García-Contreras R., Murillo R., García T., Fuel properties of tire pyrolysis liquid and its blends with diesel fuel. Energy Fuels 27 (2013) 3296–3305.
28. Yaqoob H., Teoh Y.H., Jamil M.A., Gulzar M., Potential of tire pyrolysis oil as an alternate fuel for diesel engines: a review. J. Energy Inst. (2021).
29. Campuzano F., Jameel A.G.A., Zhang W., Emwas A.-H., Agudelo A.F., Martínez J.D., Sarathy S.M., On the distillation of waste tire pyrolysis oil: A structural characterization of the derived fractions. Fuel 290 (2021) 120041.
30. Williams P.T., Bottrill R.P., Sulfur-polycyclic aromatic hydrocarbons in tyre pyrolysis oil. Fuel 74 (1995) 736–742.
31. Jantaraksa N., Prasassarakich P., Reubroycharoen P., Hinchiranan N., Cleaner alternative liquid fuels derived from the hydrodesulfurization of waste tire pyrolysis oil. Energy Conversion Management 95 (2015) 424–434.
32. Hita I., Aguayo A.S.T., Olazar M., Azkoiti M.J., Bilbao J., Arandes J.M., Castaño P., Kinetic modeling of the hydrotreating and hydrocracking stages for upgrading Scrap Tires Pyrolysis Oil (STPO) toward high-quality fuels. Energy Fuels 29 (2015) 7542–7553.
33. Hita I., Gutiérrez A., Olazar M., Bilbao J., Arandes J.M., Castaño P., Upgrading model compounds and Scrap Tires Pyrolysis Oil (STPO) on hydrotreating NiMo catalysts with tailored supports. Fuel 145 (2015) 158–169.
34. Yun G.-N., Kim K.-D., Lee Y.-K., Hydrotreating of Waste Tire Pyrolysis Oil over Highly Dispersed Ni₂P Catalyst Supported on SBA-15. Catalysts 11 (2021) 1272.
35. Choi G.-G., Oh S.-J., Kim J.-S., Non-catalytic pyrolysis of scrap tires using a newly developed two-stage pyrolyzer for the production of a pyrolysis oil with a low sulfur content. Appl. Energy 170 (2016) 140–147.
36. Miskolczi N., Angyal A., Bartha L., Valkai I., Fuels by pyrolysis of waste plastics from agricultural and packaging sectors in a pilot scale reactor. Fuel Process. Technol. 90 (2009) 1032–1040.
37. Namchot W., Jitkarnka S., Catalytic pyrolysis of waste tire using HY/MCM-41 core-shell composite. J. Anal. Appl. Pyrolysis 121 (2016) 297–306.
38. Palos R., Kekäläinen T., Duodu F., Gutiérrez A., Arandes J.M., Jänis J., Castaño P., Detailed nature of tire pyrolysis oil blended with light cycle oil and its hydroprocessed products using a NiW/HY catalyst. Waste Manage. 128 (2021) 36–44.
39. Auersvald M., Shumeiko B., Vrtiška D., Straka P., Staš M., Šimáček P., Blažek J., Kubička D., Hydrotreatment of straw bio-oil from ablative fast pyrolysis to produce suitable refinery intermediates. Fuel 238 (2019) 98–110.
40. Debek C., Walendziewski J., Hydrorefining of oil from pyrolysis of whole tyres for passenger cars and vans. Fuel 159 (2015) 659–665.
41. Hita I., Aguayo A.S.T., Olazar M., Azkoiti M.J., Bilbao J., Arandes J.M., Castaño P., Kinetic modeling of the hydrotreating and hydrocracking stages for upgrading Scrap Tires Pyrolysis Oil (STPO) toward high-quality fuels. Energy Fuels 29 (2015) 7542–7553.