Thermal Emission Monitoring of Naphthalene from Coals by Supersonic Jet Resonance Enhanced Multi-photon Ionization Time-of-Flight Mass Spectrometry Technique

Abstract

In thermal processes, such as combustion and pyrolysis reactions, the development of useful techniques for the real-time monitoring of organic compounds, like dioxin and polycyclic aromatic hydrocarbons (PAHs), has been demanded. Supersonic jet resonance enhanced multi-photon ionization time-of-flight mass spectrometry (Jet-REMPI-TOFMS) has been an effective technique in terms of the molecular selectivity, high sensitivity, and real-time analysis capability of those compounds. In this study, we developed a prototype Jet-REMPI-TOFMS system. We tried to carry out real-time observations of the naphthalene emission behavior for heated coal samples in an inert gas flow using an electric tube furnace. The behavior of naphthalene emission on the coal pyrolysis reaction was different among the types of coal species. For example, one coal sample that is used as a coking material, naphthalene, began to appear from 170°C, previously to the generation of methane and ethane, and finished at above 600°C. It is suggested that naphthalene is formed by breaking the naphthyl group contained in thermally unstable sites of coals.