Bicyclic Aromatic Hydrocarbons Research Articles

Catalytic conversion of biomass pyrolysis volatiles over composite catalysts of activated carbon and HY zeolite

Bio-oil has complex compositions and high oxygen content, which restricts its high-value utilization. Commercial activated carbon (AC) and HY zeolite were used as composite catalysts to study their effect on pyrolysis volatiles from rice straw and poplar sawdust by changing the mixing modes of two catalysts. The results showed that the loading modes of AC and HY zeolite obviously affected the products distribution and bio-oil components. The lowest yield of bio-oil was obtained when HY zeolite and AC were mechanically mixed at a mass ratio of 1:1 (YACM). But the loading mode of YACM was beneficial to the deoxidation and aromatic hydrocarbon generation. Under the mode of YACM, the aromatics content in rice straw and poplar sawdust bio-oil can be increased from 13.8% and 8.0% without catalyst to 56.4% and 53.1%, respectively. However, the layered loading with upper HY zeolite and lower AC (YTACL) was favorable for formation of phenolic compounds. The selectivity to monocyclic and bicyclic aromatic hydrocarbons followed the order of YTACL > ACTYL > YACM, and YACM > ACTYL > YTACL, respectively. Compared with HY zeolite, AC catalyst possessed smaller pore size and fewer acidity, and the active sites of AC were conducive to rearrangement of furan compounds to generate cyclopentanone, 2-cyclopentenone and methyl-cyclopentenone, and further rearrangement to form phenol. Therefore, the loading mode of YTACL exhibited a promotion effect on the formation of phenol, cresol, toluene, ethylbenzene and p-xylene. The strong acidic sites of HY zeolite were favorable for the aromatization, so the loading mode of ACTYL had good selectivity to the formation of naphthalene, methylnaphthalene, anthracene and pyrene. This work will provide a guide for products regulation from biomass pyrolysis and enrich aromatics and phenols in bio-oil.

Theoretical analysis of hydrogen solubility in direct coal liquefaction solvents

The cyclic hydrogenation technology in a direct coal liquefaction process relies on the dissolved hydrogen of the solvent or oil participating in the hydrogenation reaction. Thus, a theoretical basis for process optimization and reactor design can be established by analyzing the solubility of hydrogen in liquefaction solvents. Experimental studies of hydrogen solubility in liquefaction solvents are challenging due to harsh reaction conditions and complex solvent compositions. In this study, the composition and content of liquefied solvents were analyzed. As model compounds, hexadecane, toluene, naphthalene, tetrahydronaphthalene, and phenanthrene were chosen to represent the liquefied solvents in chain alkanes and monocyclic, bicyclic, and tricyclic aromatic hydrocarbons. The solubility of hydrogen X (mol/mol) in pure solvent components and mixed solvents (alkanes and aromatics mixed in proportion to the chain alkanes + bicyclic aromatic hydrocarbons, bicyclic saturated aromatic hydrocarbons + bicyclic aromatic hydrocarbons, and bicyclic aromatic hydrocarbons + compounds containing heteroatoms composed of mixed components) are determined using Aspen simulation at temperature and pressure conditions of 373–523 K and 2–10 MPa. The results demonstrated that at high temperatures and pressures, the solubility of hydrogen in the solvent increases with the increase in temperature and pressure, with the pressure having a greater impact. Furthermore, the results revealed that hydrogen is more soluble in straight-chain alkanes than in other solvents, and the solubility of eicosanoids reaches a maximum of 0.296. The hydrogen solubility in aromatic ring compounds decreased gradually with an increase in the aromatic ring number. The influence of chain alkanes on the solubility of hydrogen predominates in a mixture of solvents with different mixing ratios of chain alkanes and aromatic hydrocarbons. The solubility of hydrogen in mixed aromatic solvents is less than that in the corresponding single solvents. Hydrogen is less soluble in solvent compounds containing heteroatoms than in compounds without heteroatoms.

A novel symmetrically structured protonated ionic liquids for alkane de‐aromatization

AbstractThe efficient separation of aromatics/alkanes is important for the efficient utilization of fossil resources. Based on the influence of ionic symmetry structure on the polarity, melting point, interaction force, and spatial site resistance of ionic liquid solvents, a protonic ionic liquid with anionic and cationic double symmetry structure [DMI][FeCl4] was designed and synthesized for alkane de‐aromatization process, which enhances the Van der Waals forces dominated by dispersed forces with aromatics, and thus enhances the extraction efficiency of aromatic. For the binary system of dodecane/decalin + tetralin/1‐methylnaphthalene, and two simulated oil systems of six‐component straight‐sun diesel fuel and hydrofinishing LCO, [DMI][FeCl4] showed excellent de‐aromatization effects. The selectivity coefficients for monocyclic and bicyclic aromatic hydrocarbons can reach 150 and 480, respectively. When used in the de‐aromatization process of real oils, about 40% of the aromatic hydrocarbons can be removed by a single extraction using a 1:5 O/A ratio.

New biological monitoring method for 1-Naphthol and 2-Naphthol based on stir bar sportive dispersive micro extraction strategy using magnetic ionic liquid

Naphthalene is one of the few volatile bicyclic aromatic hydrocarbons and a white crystalline solid that can sublimate at room temperature. Since 2000, according to the results of animal studies on the carcinogenic effects of naphthalene, this substance has been recognized as a major problem for the environment and industrial environments. Exposure to naphthalene leads to kidney toxicity, hemolytic anemia and other health problems in the human body. The International Agency for Cancer has placed naphthalene in group 2B (probably carcinogenic to humans). 1- naphthol and 2- naphthol are biological urinary indicators of human exposure to naphthalene in work environments. For the first time in this research, the concentration of 1-naphthol and 2-naphthol in urine, which serves as an indicator of naphthalene exposure, was performed through a method known as magnetic ionic liquids-based disperse liquid–liquid microextraction (MIL-DLLME). Subsequently, the samples were analyzed using gas chromatography with a flame ionization detector (GC-FID). Additionally, the factors that influence the extraction of this metabolite, such as the quantity of extracting solvent, speed of mixing, proportion of salt added, duration of mixing, and pH value, were determined using both a two-level factorial test design and a central composite design. Calibration curves were developed under optimal conditions, and the validity of the developed microextraction method was studied with different statistical methods and the analysis of real samples. A strong linear correlation between the subpeak level and the corresponding concentrations was observed in the range of 0.5–0.002 μg/ml for 1-naphthol and 2.00–0.001 µg mL-1for 2-naphthol. In addition, the detection limit and quantitative detection limit for 1-naphthol were 0.0006 µg mL−1, 0.002 µg mL−1, and 0.0003 µg mL−1, 0.001 µg mL-1for 2-naphthol respectively. The MIL-DLLME extraction method can be regarded as an environmentally friendly microextraction technique since it eliminates the need for dispersing solvents and toxic organic solvents as extractants. Results showed that the proposed technique can be applied for biological monitoring of the biomarkers of naphthalene in the exposed workers during occupational or environmental assessments.

Effect of different SAPO-34 film thickness on coke resistance performance of SAPO-34/ZSM-5/quartz film in MTA reaction

3 Brief informative subheadings: SAPO-34 film thickness, Coke deposition analysis, Rich hierarchical pores. BackgroundComposite zeolite film had a shorter lifetime due to the easy deactivation of SAPO-34. We explored the effect of SAPO-34 film thickness on anti-coking performance of composite zeolite film. MethodsThree SAPO-34/ZSM-5/quartz films with different SAPO-34 film thicknesses were prepared for MTA reaction. TG, N2 isothermal adsorption-desorption, XPS, FTIR, and GC-MS were used to explore the content, location, and composition of coke formed on the composite zeolite film. The deactivation behaviors of three catalysts were comparatively analyzed. Significant findingsThe results showed the change in SAPO-34 film thickness could affect the reactivity. The zeolite with the SAPO-34 film thickness of 8 μm had excellent coke resistance performance because of the reasonable acid distribution and rich hierarchical pores. This could improve their coke-holding capacity and hinder the formation of graphite-like carbon. The analysis of coke species indicated that the intermediate products of the composite film were mostly tetrasubstituted methylbenzene. And the composite zeolite film with medium-thickness SAPO-34 film had the simplest composition of soluble coke, such as bicyclic or tricyclic aromatic hydrocarbons. This provided a new idea for improving the anti-coking performance of composite material.

Study of the effect of methanol/biodiesel fuel mixtures on the generation of soot particles and their oxidation reactivity

When diesel engines burn different fuels, the chemical composition of the emitted combustion particles changes, leading to changes in the oxidation characteristics of these particles and determining the regeneration strategy and service life of after treatment devices. In order to investigate the influence of methanol/biodiesel fuel mixtures on the chemical composition and oxidation activity of emitted soot matter, a test bench was built using a four-cylinder diesel engine, and soot matter in the exhaust was collected. Tests used mixed fuel with different methanol mixing ratios. By using a high-performance liquid chromatograph, a thermogravimetric analyzer, and other equipment, the changes of chemical composition and oxidation characteristics of particles were studied. The results show that as the methanol mixing ratio increases, the mass concentration of organic carbon (OC), bicyclic, and tricyclic polycyclic aromatic hydrocarbons (PAHs) in the particles increase, the mass concentration of elemental carbon (EC) and high molecular weight PAHs decreases, the concentration of nitrate ions first increases and then decreases, the activation energy decreases, and the oxidation activity increases. In general, the chemical composition of combustion particulates from methanol/biodiesel changes, and the oxidation activity is greatly improved. This research work can provide a reference for the coating design and regeneration strategy for optimizing diesel particulate filters (DPFs).

Adsorption characteristic analysis of PAHs on activated carbon with different functional groups by molecular simulation.

As widespread organic pollutants in the environment, polycyclic aromatic hydrocarbons (PAHs) greatly threaten human health. The adsorption technology has become one of the main methods to deal with PAHs because of its low cost, simple design, and no secondary pollution. Among them, solid media have strong adsorption capacities for PAHs and are widely used. In this work, activated carbon was chosen as the solid adsorbent. The adsorption behavior of three PAHs (naphthalene, anthracene, and phenanthrene) on activated carbon was investigated at the molecular level by Grand Canonical Monte Carlo (GCMC) method. The effects of different functional groups (amino, carboxyl, hydroxyl, carbonyl, and hydrogen groups) and temperature effect on the adsorption isotherms and heat of adsorption of PAHs on activated carbon were calculated. The results showed that the carbonyl functional group increased the adsorption of PAH molecules by the most considerable amount among all the functional groups. Acid functional groups were more favorable to the adsorption of PAHs than alkali functional groups. The adsorption capacity and heat of adsorption of PAHs decreased when the temperature increased. The adsorption performance of bicyclic aromatic hydrocarbons was more influenced by temperature than that of tricyclic aromatic hydrocarbons.

Reaction laws of polycyclic aromatic hydrocarbons and heteroatomic compounds in hydrocracking process

Based on the Structure Oriented Lumping (SOL) method, a molecular-level reaction kinetic model for hydrocracking process was established to investigate the reaction laws of polycyclic aromatic hydrocarbons (PAHs) and heteroatomic compounds in hydrocracking process and calculate the molecular compositions of hydrocracking products. Molecules showed different reaction laws due to the differences of the initial contents, the structural increments and their positions in the reaction network. Since the hydrodenitrogenation reactions of indole and carbazole homologs were more difficult to carry out than the hydrodesulfurization reactions of benzothiophene and dibenzothiophene homologues, the denitrification rate was lower than the desulphurization rate at the outlet of the hydrotreating section. When the reaction temperature of the hydrotreating section was 360 °C, the conversion rates of sulfides and nitrides were 98.4 % and 91.3 %, respectively. The increase of reaction temperature intensified the hydrogenation saturation of aromatics, the ring opening of naphthenes and the cracking of paraffins. As the reaction temperature of the hydrocracking section rose from 370 °C to 410 °C, more isomerized carbon ions were generated due to the β-position cracking of paraffins. The mass ratio of methylbutane to n-pentane in light naphtha increased from 1.29 to 3.08. The increase of reaction temperature accelerated the side chain cracking reactions of naphthenes with 4 or more carbon atoms in the side chains, and generates more naphthenes with 0 to 3 carbon atoms in the side chains. Aromatics mainly underwent the ring-by-ring hydrogenation saturation reactions in the hydrotreating section, and bicyclic aromatic hydrocarbons was significantly easier to be hydrogenated than monocyclic aromatic hydrocarbons.

Research of the residual content of aromatic hydrocarbons in the composition of diesel fuel after extraction cleaning

In paper the results of luminescent studies mixture of the straight-run diesel fraction with the product secondary oil refining — light gas oil coking at a mass ratio of components of 70:30% of the masses and raffinates obtained by extraction purification of the indicated feedstock with N-methylpyrrolidone and an ionic liquid - N-methylpyrrolidoneacetate synthesized based on N- methylpyrrolidone and acetic acid have been presented. A series of studies has established a relatively high extraction ability of the ionic liquid, compared with N-methylpyrrolidone. Since under similar conditions of selective purification using the specified ionic liquid as the extractant, bicyclic aromatic hydrocarbons are almost completely removed from the composition of the test mixture of the diesel fraction. Keywords: raffinate; luminescent studies; extraction purification; UV spectral analysis; ionic liquid; N-methylpyrrolidone.

Using fluorescence analysis to find traces of accelerants in the thermal decomposition products of laminates

Introduction . To enhance combustion in arson attacks, arsonists often use accelerants, or easily accessible petrochemicals, such as gasoline, diesel fuel, as well as their mixtures. As a rule, accelerants are submitted for investigation as traces left on the surface or inside objects of evidence. If objects of evidence are damaged by the fire heat, thermal decomposition products may be formed, and their composition is similar to the one of petrochemicals. Goals and objectives . The goal of the study is to use fluorescence spectroscopy to study extractive components of the burnt laminate, as one of the most common types of floor coverings, and identify their influence on detec- tion of accelerants. Methods . The study is focused on extracted samples of the Tarkett laminate, having physical dimensions of 50 × 50 mm 2 , exposed to the thermal impact in a muffle furnace at the temperatures of 300, 400 and 500°C for 2–10 minutes. The samples were studied using fluorescence spectroscopy at the fluorescence excitation wavelength of 255 nm. Discussion . The fluorescence spectra of the laminate samples, showing signs of minor thermal damage (color change), include a single wide peak of 300–410 nm with a maximum in the area of 340 – 370 nm. The shift of the fluorescence maximum and the emergence of peaks in other areas of the spectrum are typical for laminate samples, on the surface of which a carbonized layer is formed at the temperature of 300°C (600 s) and 400°C (240, 360 s). An increase in the thermal damage of samples, accompanied by the destruction of the carbonized residue, leads to the decrease in the fluorescence intensity of their extractive components to background values. Conclusion . The fluorescence spectra of the laminate samples, obtained by means of burning at 400°C for 240–360 s, have peaks in the area of bicyclic and tricyclic aromatic hydrocarbons, which impede the identifiability of accelerant traces that may be present as heavy oil fractions (oils, lubricants, fuel oil), highly burnt diesel fuels.

Pyrolysis behavior of coal in a moving bed with baffled internals under different residence times

In view of the problems faced by a conventional moving bed coal pyrolysis process, such as the inability to deal with pulverized coal, low light tar yield, poor tar quality, etc., a moving bed pyrolysis process with baffled internals was developed to control heat and mass transfer of the gas-solid two-phase and the pyrolysis reaction process. The multi-stage gas gathering system can collect the oil and gas products released in different pyrolysis stages of coal in time. The pyrolysis behavior and product quality of Naomaohu coal at different temperatures and residence times were investigated. The results show that the baffle internals enhance heat and volatile matter transfer among particles, enabling it to process 0.4–6.0 mm pulverized coal. When pyrolysis temperature is 550°C and residence time is 3.0h, the pyrolysis tar yield reaches the highest 11.38%, which is 86.87% of the Gray-King assay yield, and the mass fraction of light components below 360°C in the tar fraction is 85.0%. With the extension of the residence time, the H2 volume fraction in the pyrolysis gas increases from 22.1% to 35.1%, and the CO volume fraction increases from 8.0% to 9.5%. Tar yield in the first and second layer reactors increases with increasing residence time, and the tar yield in the third and fourth layer reactors isobtained when the residence time is 2.0 h. As the number of beds increases, content of light components in the tar simulated distillation fraction increases; content of tar aliphatic hydrocarbon compounds decreases, and that of monocyclic aromatic hydrocarbons and bicyclic aromatic hydrocarbons gradually increases. Based on the above results, it provides technical support for large-scale industrial processing of small particle size pulverized coal, and preparation of higher yield and quality tar.

Azulene-Pyridine-Fused Heteroaromatics.

Azulene, a nonbenzenoid bicyclic aromatic hydrocarbon with unique electronic structure, is a promising building block for constructing nonbenzenoid π-conjugated systems. However, azulene-fused (hetero)aromatics remain rare as a result of limited synthetic methods. We report herein the unexpected synthesis of azulene- and pyridine-fused heteroaromatics Az-Py-1, a seven fused ring system with 30π electrons, by reductive cyclization of a 1-nitroazulene. The structure of Az-Py-1 was unambiguously confirmed by single-crystal X-ray analysis, and analogues Az-Py-2-Az-Py-6 were also synthesized, demonstrating that this is an effective method for constructing azulene- and pyridine-fused heteroaromatics. Theoretical calculations and photophysical and electrochemical studies of Az-Py-1-Az-Py-6 suggest their potential as semiconductors, and the single-crystal ribbons of Az-Py-1 show high hole mobilities up to 0.29 cm2 V-1 s-1.

(Mono-) Exposure to Naphthalene in the Abrasives Industry: Air Monitoring and Biological Monitoring.

Exposure to the bicyclic aromatic hydrocarbon naphthalene occurs in most cases along with other polycyclic aromatic hydrocarbons. Here we report from an investigation of 63 healthy, non-smoking male employees in the abrasives industry where naphthalene is the only relevant chemical exposure. Exposure assessment was performed using a combination of Air and Biological Monitoring over nearly a whole working week (Mo.-Th.). Air measurements were carried out during the shift on Thursday with the GGP mini-sampling system, combining particle and vapour sampling at low flow rates. In urine spot samples, the metabolites 1- and 2-naphthol were measured Mo.-Th. pre- and post-shift (for the reference group only Mo. pre- and Th. post-shift). With regard to naphthalene concentrations measured in air and concentrations of its metabolites (1- and 2-naphthol) in urine, study participants could be divided into a high and a low exposure group, and a reference group. The naphthalene concentration in air was in the range of 0.1-11.6 mg m-3, and naphthol concentrations (sum of 1- and 2-naphthol) in post-shift urine were in the range of <1 to 10 127 µg l-1. Naphthalene concentrations in air and naphthol concentrations in urine were closely correlated, indicating mainly airborne exposure at the investigated workplaces. As expected from toxicokinetic data, internal body burden increased slightly during a working week and did not completely decline over a work-free weekend to background concentrations observed in occupationally not exposed persons. Taking into account the observed increase in pre- and post-shift values during the working week, urine sampling for Biological Monitoring at workplaces should be carried out after several preceding shifts. Our data allow the derivation of biological limit values for the sum of 1- and 2-naphthol in urine corresponding to occupational exposure limits for naphthalene in air.

Combined effects of cadmium and oil sludge on sorghum: growth, physiology, and contaminant removal.

The physiological and biochemical responses of Sorghum bicolor (L.) Moench. to cadmium (Cd) (30mgkg-1) and oil sludge (OS) (16gkg-1) present in soil both separately and as a mixture were studied in pot experiments. The addition of oil sludge as a co-contaminant decreased Cd entry into the plant by almost 80% and simultaneously decreased the stimulation of superoxide dismutase (SOD) and peroxidase. The decrease in glutathione reductase (GR) activity and the increase in glutathione-S-transferase (GST) activity under the influence of oil sludge indicated that its components were detoxified by conjugation with glutathione. Cd additionally activated the antioxidant and detoxifying potential of the plant enzymatic response to stress. This helped to enhance the degradation rate of oil sludge in the rhizosphere, in which the participation of the root-released enzymes in the degradation could be possible. Cd increased the extent of soil clean-up from oil sludge, mainly owing to the elimination of paraffins, naphthenes, and mono- and bicyclic aromatic hydrocarbons. The mutual influence of the pollutants on the biochemical responses of sorghum and on soil clean-up was evaluated. The results are important for understanding the antistress and detoxification responses of the remediating plant to combined environmental pollution.

Effect of Composition of Cobalt-Molybdenum-Containing Sulfonium Thiosalts on the Hydrogenation Activity of Nanosized Catalysts In Situ Synthesized on Their Basis

Cobalt-molybdenum-containing thiosalts with different composition of the sulfonium cation are prepared. The activities of sulfide catalysts in situ synthesized on their basis in the hydrogenation of substituted naphthalenes are compared. It is shown that the sulfonium cation composition affects the morphology of the sulfide particles and the phase composition of the catalyst. It is demonstrated that the conversion of model alkyl-substituted bicyclic aromatic hydrocarbons is higher in the presence of the catalyst prepared from the phenylsulfonium thiosalt.

Azulene-Based BN-Heteroaromatics.

Azulene, a nonalternant bicyclic aromatic hydrocarbon, has unique chemical and physical properties and is considered to be a promising building block for constructing novel polycyclic aromatic hydrocarbons (PAHs) and heteroaromatics. We present here the first two azulene-based BN-heteroaromatics Az-BN-1 and Az-BN-2. The chemical structures and optical and electrochemical properties of both compounds have been investigated, as well as their sensing behavior in response to fluoride ion. Az-BN-1 and Az-BN-2 show different photophysical properties from other reported BN-embedded PAHs, such as lower band gaps and unusual fluorescence. In addition, Az-BN-1 and Az-BN-2 exhibit unexpected deboronization upon addition of trifluoroacetic acid, which distinguishes them from other reported BN-heteroaromatics and can be ascribed to the unique property of the azulene unit.

Nickel–Tungsten and Nickel–Molybdenum Sulfide Diesel Hydrocarbon Hydrogenation Catalysts Synthesized in Pores of Aromatic Polymer Materials

Porous aromatic polymer materials based on tetraphenylmethane molecules linked by methylene groups have been synthesized. By impregnating these materials with nickel–tungsten and nickel–molybdenum thiosalts, catalysts for the hydrogenation of bicyclic aromatic hydrocarbons of the diesel fraction have been prepared. Nanoparticles of the active sulfide phase are formed in support pores during the reaction; it is assumed that after the formation of the nanoparticles, the support material will undergo partial degradation to rearrange the mesoporous structure into a macroporous structure providing the best diffusion of substrates to the surface of the sulfide nanoparticles. The synthesized catalysts have been tested in the hydrogenation of naphthalene and naphthalene derivatives at a hydrogen pressure of 5 MPa and a temperature of 380°C.

Composition of Oil Fractions Obtained in Combined Thermolysis of Heavy Sulfur-Rich Petroleum and Oxidation of Activated Carbon with Supercritical Water–Oxygen Fluid

The composition of oil fractions (OFs) obtained via the conversion of heavy sulfur-rich petroleum is studied with physicochemical methods. Petroleum is supplied to the upper part of a vertical tubular reactor packed with activated carbon (AC), through which a supercritical water-oxygen fluid is pumped. The experiment is carried out under the following conditions: pressure 30 MPa; temperatures in the upper, middle, and lower parts of the reactor of 673, 723, and 723 K, respectively; and the flow rates of oxygen, petroleum, and water of 0–3.5, 4, and 6 g/min, respectively. Time dependences between the wall temperature of the reactor and power of ohmic heaters show that the autothermal conversion regime is achieved due to heat release during the combustion of high-molecular petroleum components accumulated in the AC bed. The movement of a combustion front along the reactor axis is found. Isoprenoid and normal alkanes, 1-alkyl-2,3,6-trimethylbenzenes, and alkyl derivatives of benzothiophenes and dibenzothiophenes are the main components of OFs of the initial petroleum. A yield of OFs, whose content in the liquid products exceeds 90%, has an extreme dependence on the oxygen flow rate. An increase in the oxygen flow rate (and, consequently, an increase in temperature of the reaction mixture due to heat release during combustion) leads to an increase in the content of alkyl derivatives of bicyclic and tricyclic aromatic hydrocarbons, as well as benzothiophenes and dibenzothiophenes in OFs of the products. The content of components boiling at T < 493 K in OFs of the products increases 2–3-fold in comparison with those of the initial petroleum.

Naphthalene Toxicity-Winter Poison in Teenager

Introduction: Naphthalene is bicyclic aromatic hydrocarbon most commonly used as insect and moth repellent household product for storing clothes. The toxic manifestations have been proposedly due to increased free radical formation leading to lipid peroxidation and formation of epoxide and further ultimate DNA damage. Naphthalene toxicity manifests at doses ranging 5 to 15 gms to incidences as low as 2 gm have been reported in children.

Formation of bicyclic polycyclic aromatic hydrocarbons (PAHs) from the reaction of a phenyl radical with cis-3-penten-1-yne.

The formation of polycyclic aromatic hydrocarbons (PAHs) on the C11H11 potential energy surface involved in the reactions of a phenyl radical (C6H5) with cis-3-penten-1-yne (cis-C1H Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> C2–C3H Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> C4H–C5H3, referred to as C5H6) and its three radicals (CHC–ĊCH–CH3, CHC–CHĊ–CH3, and cis-CHC–CHCH–ĊH2, referred to as the C3-, C4-, and C5-radicals with the same chemical components, C5H5) assisted by H atoms is investigated by performing combined density functional theory (DFT) and ab initio calculations. Five potential pathways for the formation of PAHs have been explored in detail: Pathways I–II correspond to the reaction of C6H5 with C5H6 at the C1 and C2 position, and Pathways III–V involve the reaction of C6H5 with the C3-, C4-, and C5-radicals with the assistance of H atoms. The initial association of C6H5 with C5H6 or C5H5 is found to be highly exothermic with only minor barriers (1.4–7.1 kcal mol−1), which provides a large driving force for the formation of PAHs. The hydrogen atom is beneficial for the ring enlargement and ring formation processes. The present calculations predict 9 potential PAHs, six (CS6, CS10, CS13, CS26, CS28 and CS29) of which are indicated to be energetically more favorable along Pathways I, III, IV and V at low temperature. The calculated barriers for the formation of these PAHs are around 19.2–38.0 kcal mol−1. All PAHs products could be formed at flame temperature, for the medium barriers are easily overcome in various flame conditions. The theoretical results supplement the PAH formation pathway and provide help to understand PAH growth mechanism.