Production of cleaner waste tire pyrolysis oil by removal of polycyclic aromatic hydrocarbons via hydrogenation over Ni‐based catalysts

Abstract

Summary This research aimed to improve the quality of waste tire pyrolysis oil (WTPO) via hydrogenation to eliminate polycyclic aromatic hydrocarbons (PAHs), which are classified as toxic compounds or precursors to induce the formation of particulate matter. Given the presence of organosulfurous compounds in WTPO, this research was consisted of two steps. First, the hydrogenation of naphthalene, a model PAH compound, was used to screen for suitable promoters [molybdenum (Mo), tungstate (W), and platinum (Pt)] for nickel‐supported gamma‐alumina (Ni/γ‐Al2O3) catalyst to provide a high sulfur tolerance and high PAH hydrogenation efficiency. Second, the obtained suitable catalysts were applied for the hydrogenation of 50 wt% WTPO solution in decane containing 15 982 ppm PAHs and a 0.75 wt% sulfur content. Although the NiPt/γ‐Al2O3 catalyst exhibited the highest performance with 83.8% naphthalene conversion under 40 bar initial H2 pressure at 350°C for 6 hours, it was less tolerant to the presence of thiophene, one of the organosulfurous compounds found in WTPO. Thus, the NiMo/γ‐Al2O3 and NiW/γ‐Al2O3 catalysts were selected for WTPO hydrogenation. The PAHs hydrogenation and hydrodesulfurization occurred simultaneously in both catalytic systems. Under 50 bar initial H2 pressure at 350°C, the NiMo/γ‐Al2O3 catalyst had a higher ability for hydrodesulfurization (98.4% maximum sulfur removal) than hydrogenation of PAHs (66.0% removal of PAHs), whereas NiW/γ‐Al2O3, with lower acidity, showed a preference for hydrogenation of PAHs (71.1% removal of PAHs) with a lower hydroisomerization efficiency (74.2% sulfur removal). Moreover, the chemical structure of PAHs affected the ability to be eliminated by hydrogenation. PAHs having unsubstituted rings could be easily hydrogenated, while the removal of PAHs containing alkyl substituents in both aromatic rings required severe reaction conditions due to their high steric hindrance for adsorption onto the catalyst active sites.

Hydroisomerization Principles of Acenaphthene to Alkyladamantanes over Modified USY-Supported Pt Catalysts

“…It was widely accepted that different temper-Table 1. 27 The Si/Al of the samples from SEM-EDS. atures correspond to different acid site strengths.…”

“…There were two processes involved in the conversion of PAHs to AAs, hydrogenation and ring-shift isomerization reactions. , The hydrogenation of PAHs has been reported, and the corresponding mechanisms have been clearly identified. The process was a reversible process of ring-by-ring hydrogenation, , which mainly depended on the metal .…”

Development and Application of a Novel Multiloop Splitter-Based Non-cryogenic Artificial Trapping Modulation System in Comprehensive Two-Dimensional Gas Chromatography

“…However, the elimination of PAHs in the WTPO has gained much less attention. The previous literature reported that nickel–tungsten (Ni–W) supported on γ-Al 2 O 3 had a preference for hydrogenation to eliminate PAH species in WTPO with 71.1% removal …”

“…The previous literature reported that nickel−tungsten (Ni−W) supported on γ-Al 2 O 3 had a preference for hydrogenation to eliminate PAH species in WTPO with 71.1% removal. 33 According to the complexity of chemicals in WTPO, the technique of SNAT modulation was proposed in this study to improve the modulation capability by artificial splitting-andtrapping of highly volatile compounds without the use of cryogens. The approach also enables the use of a longer 2 D column and P M and could be performed within a single injection.…”