Investigation of Naphthalene Formation During Petroleum Refining Processes and Mitigation Strategies

Abstract

Naphthalene formation during petroleum refining processes presents significant operational, environmental, and regulatory challenges due to its toxicity, persistence, and contribution to polycyclic aromatic hydrocarbon (PAH) emissions. This study investigates the mechanisms of naphthalene formation across key refining units, including fluid catalytic cracking (FCC), delayed coking, and catalytic reforming. It evaluates potential mitigation strategies to reduce its production. A mixed-methods approach was employed, combining process simulation using Aspen HYSYS, gas chromatography–mass spectrometry (GC-MS) analysis of hydrocarbon samples, and literature-based assessment of mitigation techniques.

The results indicate that naphthalene formation increases significantly with rising process temperature and severity, with FCC simulation data showing an exponential increase in yield from 0.42 wt% at 480°C to 1.25 wt% at 540°C. GC-MS analysis further revealed that delayed coking units exhibit the highest naphthalene concentrations (87 ppm), followed by catalytic reforming (61 ppm) and FCC units (38–52 ppm). These findings confirm that thermal cracking environments are the dominant contributors to naphthalene formation, driven by radical mechanisms and extended residence times.

Evaluation of mitigation strategies shows that feedstock hydrotreating is the most effective method, achieving up to 60–75% reduction in naphthalene formation by removing aromatic precursors prior to catalytic processing. Catalyst modification and process optimisation also contribute to reductions, though with varying degrees of effectiveness and subject to operational constraints.

The study concludes that naphthalene formation is primarily governed by process severity, feedstock composition, and reaction pathway dynamics. An integrated mitigation approach combining hydrotreating, catalyst optimisation, and process control is recommended to minimise emissions and improve refinery performance.