Formation of Polycyclic Aromatic Hydrocarbons (PAHs) in Thermal Systems: A Comprehensive Mechanistic Review

Energy & Fuels, Journal Year: 2024, Volume and Issue: 38(22), P. 21735 - 21792

Published: Nov. 1, 2024

Polycyclic aromatic hydrocarbons (PAHs) are formed invariably through oxidative and pyrolytic degradation of organic materials fuels. Understanding the highly complex reaction mechanisms that dictate their synthesis in thermal systems has been given a great deal focus. Such interest stems from two broad perspectives, namely, enhancing efficiency combustion system, energy recovery fuels protecting environment. Health environmental effects widely vary among PAHs where certain compounds exhibit carcinogenic tendencies. This critical review mainly aims to provide general mechanistic view commonly discussed formation pathways PAHs. The attained knowledge often incorporates experimental measurements kinetic modelings, as well mapped out by quantum chemical calculations. A sampling species is typically conducted via molecular beam (MB)–mass spectroscopy (MS) technique connected reactor (flow reactor, jet-stirred or shock tube). Generally, PAH precursors encompass four categories (radicals molecules): acetylenic compounds, alkyl radicals, phenyl resonance-stabilized cyclic radicals. Overall, relevance mechanism depends on consistency between proposed model pathways, profiles products at investigated conditions (i.e., temperatures, pressures, distance burners). effect seeding common precursors, with other explored surveying pertinent studies. Growth higher PAHs, including toxic pyrene, most likely involves hydrogen abstraction acetylene addition (HACA)-like starting anthracene bimolecular reactions involve benzyl radicals indene molecules. synergistic collaboration different suggested account for observed fast growth rate As experimentally shown, sequential mass 15 u, 24 26 74 indicate routes MAC, HACA, HAVA*, PAC routes, respectively. Whether physical process initial step conversion into soot (the inception step) still debated literature. Recent evidence underscores commence creating dimers clustering under real flame 400–1200 K). Formation synthetic natural polymers ensues condensation fragments structural arrangements polymeric entities, prior fragmentation. surveyed presented this will be useful readers who aim comprehend chemistry underlying systems.

Language: Английский

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Fast Pyrolysis of Cigarette and Cigar Leaves: Differential Analysis of Their Heavy Products by Ultrahigh‐Resolution Mass Spectrometry

Rapid Communications in Mass Spectrometry, Journal Year: 2025, Volume and Issue: 39(10)

Published: Feb. 18, 2025

ABSTRACT Rationale The cigars have characteristic flavors in smoke when compared with cigarettes, and from various origins also a difference taste. However, little information can be found about the chemical components of smokes between cigar cigarette as well cigars, so it is interesting to compare their pyrolysis product distribution. Methods leaves were pyrolyzed microfluidized‐bed reactor, vapors condensed collected using cold traps. Mass spectrometric analysis liquids was performed utilizing electrospray ionization‐orbitrap mass spectrometry both positive negative ion modes. Results spectra condensable products three tobacco obtained by Orbitrap‐MS ESI DBE values (to carbon atom number) relative distribution nitrogen or oxygen different carefully discussed. Conclusion main relates N 1 –N 2 class compounds high‐mass range highly unsaturated nitrogenated compounds, while one two associated C x H y O z 5–9 30‐50 w compounds. Besides, oxygenated that fall into H/C > O/C < ranges are for Dominican cigar.

Language: Английский

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In-Situ Enrichment Of Light/Heavy Components and Selective Cracking Through Internals-Regulated Pyrolysis

Published: Jan. 1, 2024

Language: Английский

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Investigating the Kinetics of Heterogeneous Lipid Ozonolysis by an Online Photoionization High-Resolution Mass Spectrometry Technique

Analytical Chemistry, Journal Year: 2024, Volume and Issue: 96(49), P. 19576 - 19584

Published: Nov. 21, 2024

Lipid oxidation-induced imbalance in the redox system is one of key causative factors leading to accelerated aging living organisms and related diseases. Online sampling analysis heterogeneous ozonolysis kinetics lipid aerosols are highly important revealing oxidation-driven process lipids. In this paper, an online detection method based on atmospheric pressure photoionization combined with ultrahigh resolution mass spectrometry (APPI-HRMS) developed for real-time reactions between particles (oleic acid squalene) ozone. The APPI-HRMS technique serves as ideal platform analyzing oxidation particles, exhibiting remarkable stability, sensitivity, responsiveness across a wide range particle concentrations. Owing distinctive characteristics soft ionization, effective rate was quantitatively measured. This has facilitated series fingerprint particle-phase products, including aldehydes, secondary ozonides, hydroperoxides. Additionally, evolution these products ozone concentration captured. Consequently, ability assessing multiphase organic been demonstrated, positioning it promising feasible tool particles.

Language: Английский

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