Formation Of Aromatic Hydrocarbons Research Articles

Synthesis of sustainable chemicals from waste tea powder and Polystyrene via Microwave-Assisted in-situ catalytic Co-Pyrolysis: Analysis of pyrolysis using experimental and modeling approaches

In the current study, catalytic co-pyrolysis was performed on waste tea powder (WTP) and polystyrene (PS) wastes to convert them into value-added products using KOH catalyst. The feed mixture influenced the heating rates (17–75 °C/min) and product formation. PS promoted the formation of oil and WTP enhanced the char formation. The maximum oil yield (80 wt%) was obtained at 15 g:5 g, and the maximum char yield (44 wt%) was achieved at 5 g:25 g (PS:WTP). The pyrolysis index (PI) increased with the increase in feedstock quantity. High PI was noticed at 25 g:5 g, and low PI was at 5 g:5 g (PS:WTP). Low energy consumption and low pyrolysis time enhanced the PI value. Significant interactions were noticed during co-pyrolysis. The obtained bio-oil was analyzed using GC–MS and a plausible reaction mechanism is presented. Catalyst and co-pyrolysis synergy promoted the formation of aliphatic and aromatic hydrocarbons by reducing the oxygenated products.

Suppression of the phenolic SOA formation in the presence of electrolytic inorganic seed

Phenolic compounds are largely attributed to wildfire gases and rapidly react with atmospheric oxidants to form persistent phenoxy free radicals, which influence atmospheric chemistry and secondary organic aerosol (SOA) formation. In this study, phenol or o-cresol was photochemically oxidized under various conditions (NOx levels, humidity, and seed conditions) in an outdoor photochemical reactor. Unexpectedly, SOA growth of both phenols was suppressed in the presence of salted aqueous aerosol compared to non-seed SOA. This discovery is different from the typical SOA formation of aromatic or biogenic hydrocarbons, which show noticeably higher SOA yields via organic aqueous reactions. Phenol, o-cresol, and their phenolic products (e.g., catechols) are absorbed in aqueous aerosol and form phenoxy radicals via heterogeneous reactions under sunlight. The resulting phenoxy radicals are redistributed between the gas and particle phases. Gaseous phenoxy radicals quickly react with ozone to form phenyl peroxide radicals and regenerated through a NOx cycle to retard phenol oxidation and SOA formation. The explicit oxidation mechanisms of phenol or o-cresol in the absence of aqueous phase were derived including the Master Chemical Mechanism (MCM v3.3.1) and the path for peroxy radical adducts originating from the addition of an OH radical to phenols to form low volatility products (e.g., multi-hydroxy aromatics). The resulting gas mechanisms of phenol or o-cresol were, then, applied to the Unified Partitioning Aerosol Phase Reaction (UNIPAR) model to predict SOA formation via multiphase partitioning of organics and aerosol-phase oligomerization. The model well simulated chamber-generated phenolic SOA in absence of wet-inorganic seed, but significantly overestimated SOA mass in presence of wet seed. This study suggests that heterogeneous chemistry to form phenoxy radicals needs to be included to improve SOA prediction from phenols. The suppression of atmospheric oxidation due to phenoxy radicals in wet inorganic aerosol can explain the low SOA formation during wildfire episodes.

Effect of Apple Polyphenol and Three Antioxidants on the Formation of Polycyclic Aromatic Hydrocarbon in Barbecued Pork

Polycyclic aromatic hydrocarbons (PAHs) widely exist in food, which potentially harm human health. This study compared the effect of apple polyphenol (AP) and three antioxidants – ascorbic acid, tert-butyl hydroquinone and butylated hydroxytoluene on barbecued pork. The inhibition pathway of PAHs in barbecued pork were investigated by measuring DPPH radical scavenging rate, peroxide value (POV), and thiobarbituric acid value (TBARs). The results indicated that AP and antioxidants showed positive effects in inhibiting of PAHs formation (20.03–37.36%), scavenging DPPH radical activity (48.56–64.37%), reducing POV value (45.08–64.89%), and TBARs value (13.74–32.72%). Based on strong correlation between the PAHs content and the POV (r = 0.844, p = 0.017) and TBARs values (r = 0.825, p = 0.022) analyzed by Pearson correlation, AP can be used to control the formation of PAHs. The inhibition effect of AP on PAHs showed concentration-dependent. OPLS-DA analysis revealed that 0.20% AP had the best inhibition on PAH in barbecued pork, and elasticity, cohesiveness, adhesion, chewiness, and recovery of barbecued pork were improved significantly.

Mechanistic insights into the chemical structural changes of lignite on potential formation of the polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) generated during lignite combustion and gasification are highly carcinogenic, teratogenic, and mutagenic. Leveraging solvent extraction without damaging the macromolecular structure of lignite could help better understand the chemical structure and further clarify the possible source of PAHs, and the possibility of their elimination, thereby improving lignite utilization efficiency. In this study, methanol, ethanol, dichloromethane, and n-hexane were used to extract the feedstock at room temperature, and the constituents of the extracts were analyzed using GC-MS. The study showed that poly-condensed aromatic constituents were present in relatively high percentage in the extracts, due to the polarity effect of solvents, and could have a noticeable impact on the generation of PAHs. The aromatic hydrocarbons content accounts for nearly 70% of the total, which is about 10% higher than that of aliphatic hydrocarbons, and mainly exist in the form of 2 and 3 rings. Furthermore, FTIR, XRD and Raman were used to evaluate the macromolecular structural characteristics and the relevant information of the lignite bonds. The study demonstrated that the rupture of weak C–O or C–C covalent bonds promoted a more aromatic product, as strongly cross-linked networks of polycyclic aromatic components remained. The potential generation of PAHs was comprehensively ascertained by evaluating the extracts obtained at room temperature and products of combustion test， which can provide more information on PAHs pollutants.

Synthesis of isocoumarins and PAHs with electron-withdrawing substituents: Impact of the substituent nature on the photophysical behavior

The efficient conditions for rhodium catalyzed oxidative coupling of electron-poor carboxylic acids with diphenylacetylene have been optimized. The best protocol uses Ag2CO3 as an oxidant and DMF as a solvent. The reactions smoothly proceed with the formation of isocoumarins and polycyclic aromatic hydrocarbons (PAHs). The isonicotinic, coumalic, coumarin-3-carboxylic, 4-nitrobenzoic, 4-cyanobenzoic, 4-(ethoxycarbonyl)benzoic, and terephthalic acids were successfully involved in the annulation. In contrast, in the case of picolinic acid, the formation of the stable chelate complex Cp*RhCl(O,N-pic) prohibits the catalytic reaction. The photophysical properties of isocoumarins and PAHs in solutions, such as fluorescence emission and solvatochromic effects, have been studied. In particular, the isocoumarin dyes demonstrate a phenomenon of aggregation-induced emission, while PAHs with electron-withdrawing substituents exhibit strong fluorescence emission in the violet region (370–390 nm) with quantum yields up to 55%.

Combined high-pressure experimental and kinetic modeling study of cyclopentene pyrolysis and its reactions with acetylene

A combined experimental and kinetic modeling study is presented to improve the understanding of the formation of polycyclic aromatic hydrocarbons (PAHs) from neat cyclopentene and cyclopentene/acetylene mixtures. High-pressure experiments are conducted for the first time over a temperature range covering 930–1650 K using a single-pulse shock tube coupled to gas chromatography/gas chromatography-mass spectrometry (GC/GC–MS) techniques. Several updates and inclusions, mainly regarding the reactions involving C5 molecules and radicals, are made in our on-going PAH kinetic model, which shows satisfactory predictive performances for the speciation measurements obtained in the current work and in the literature. On the basis of the experimental observations and modeling analyses, the reaction pathways active during the pyrolysis of cyclopentene are illustrated and the effects of acetylene addition as co-reactant on the PAH chemistry are assessed. In all of the cases investigated, it is noted that the cyclopentadienyl radical largely participate in the formation of mono-aromatic hydrocarbons (benzene and styrene) and PAHs (indene, naphthalene and phenanthrene).

Catalytic pyrolysis of cotton stalk to produce aromatic hydrocarbons over Fe modified CaO catalysts and ZSM-5

In this study, a novel method for the enhanced production of aromatic hydrocarbons by biomass pyrolysis with Fe modified CaO and ZSM-5 was proposed. The feasibility of aforementioned method and related reaction mechanism for the formation of aromatic hydrocarbons were investigated in Py-GC/MS. The results showed that Fe modification of CaO increased its specific surface area and generated Ca2Fe2O5. As a result, 5Fe/CaO and 10Fe/CaO (CaO modification by 5 wt% and 10 wt% Fe, respectively) promoted the cracking of lignin oligomer to phenols, ketonization of acetic acid to acetone, and dehydration of levoglucosan to furfural. Therefore, the addition of 5Fe/CaO or 10Fe/CaO in cotton stalk catalytic pyrolysis with ZSM-5 favored the formation of BTX obviously. The peak area % of BTX obtained by dual-catalyst of 10Fe/CaO and ZSM-5 can reached up to 67.5%, boosting 10.94% and 2.94% than ZSM-5 alone and dual-catalyst of CaO and ZSM-5, respectively. Meanwhile, the peak area of BTX obtained by dual-catalyst of 5Fe/CaO and ZSM-5 boosts 9.59% and 7.11% than ZSM-5 alone and the dual-catalyst of CaO and ZSM-5, respectively.

The effects of 1-methylnaphthalene addition to n-dodecane on the formation of soot and polycyclic aromatic hydrocarbons in laminar coflow diffusion flames

1-Methylnaphthalene (1-MN) is a typical diaromatic component in petroleum-based fuels and has been widely chosen to represent aromatic fractions in surrogate fuels of diesel and jet fuels. In this study, experimental and modeling studies were performed to investigate the formation of typical polycyclic aromatic hydrocarbons (PAHs) and soot in coflow methane/air diffusion flames doped with 1-methylnaphthalene/n-dodecane mixtures, and explore chemical effects of 1-methylnaphthalen on key soot formation steps. The laser-induced incandescence (LII) and laser-induced fluorescence (LIF) techniques were used to obtained the soot volume fraction and relative concentration of typical PAHs along the flame centerline, respectively. A novel apparatus-independent indicator, yield aromatic index (YAI), was first proposed to quantify the formation tendency of a specific aromatic product in a flame. It can be found that the addition of 1-methylnaphthalene in the fuel mixtures has a significantly promoting effect on soot formation processes. The correlation between the mass fraction of 1-methylnaphthalene and sooting tendency shows a strong linear relationship. As to the PAH formation tendency, YAIA2R5 have the smaller deviations from corresponding YSIs than YAIA2&A3 and YAIA4, which indicating that A2R5 can be a type of important species leading to soot inception and have strong contribution to soot formation. Through the chemical kinetic analysis, A2R5 is proved to be a key coupling point of two A4 formation pathways, which start from n-dodecane and 1-methylnaphthalene, respectively. As a small amount of 1-methylnaphthalene is introduced into the fuel, the dominant approach to A2R5 rapidly shifts to a more efficient pathway, and is continually enhanced with increasing 1-methylnaphthalene at a moderate trend. The results reveal that 1-methylnaphthalene in the fuel can stride over the rate limiting step of the soot formation process of non-aromatic fuels, eventually leading to an obviously increasing sooting tendency. This study aims to provide useful information for the development of soot nucleation mechanisms and the control of soot formation processes.

Kinetic analysis of the pathways to naphthalene formation from phenyl + 1,3-Butadiyne reaction

Having a better understanding of polycyclic aromatic hydrocarbon (PAH) formation under flame conditions contributes to optimizing the fuel reforming process, where soot poisons the downstream catalyst. In this work, the phenyl + 1,3-Butadiyne reaction is systematically investigated to examine its contribution to naphthalene formation. The reaction potential energy surfaces were calculated using DFT/M06–2X/cc-pvtz and G4 methods. The temperature- and pressure-dependent reaction rate constants were calculated using RRKM theory with solving master equation. The results revealed that 2-naphthyl could be directly formed by phenyl + 1,3-Butadiyne reaction. With H assistance, naphthalene could be formed by the pathway of phenyl + 1,3-Butadiyne → C6H5CHCCCH (+H) → C6H5CHCHCCH (+H) →naphthalene +H. The proposed pathway is kinetically favorable, and featured by relatively low energy barrier. The importance of the proposed pathway reaction was confirmed in a premixed and a diffusion C2H4/O2/Ar flame simulations, where the enhancement of naphthalene by the investigated reactions is notable. The mole fraction of A2 is promoted by a factor of 10% in premix C2H4/O2/Ar flame and 30% in C2H4/O2/Ar counterflow flame, bringing the prediction results closer to the experimental results. The relative contribution of different reaction route to A2 formation is evaluated for HACA, cyclopentadienyl radical-cyclopentadienyl radical, phenyl-vinylacetylene[1], benzyl radical-propargyl radical, indene-CH2 and phenyl-1,3-Butadiyne routes in premixed and diffusion C2H4/O2/Ar flames. This work suggests that the PAH growth by 1,3-Butadiyne addition reaction is an effective pathway for A2 formation, which should be considered in future PAH mechanism.

Measurements of Soot Particulate Emissions of Ammonia-Ethylene Flames Using Laser Extinction Method

Ammonia (NH3) has emerged as an attractive carbonless fuel that can be co-fired with hydrocarbon fuel to reduce carbon dioxide emissions. To understand the influence of NH3 on soot formation when co-fired with hydrocarbons, the soot formation propensity is experimentally investigated via a laminar diffusion jet flame. A stable ethylene (C2H4) jet flame doped with NH3 at different volume percentages was established for the investigation of soot formation tendency. OH* chemiluminescence imaging revealed the change of flame structure, in which the signals emitted from the heat release region weakened with increasing NH3 addition, while the peak intensity shifted from the flame wings towards flame centerline region. The laser extinction method used to measure the soot volume fraction (SVF) at different heights above the burner, which showed the effect of NH3 on soot suppression is significant, owing to the interaction between N-containing compounds with carbon atoms that result in the reduction of key intermediate products required for the formation of benzene and polycyclic aromatic hydrocarbons (PAH). The effect of soot inhibition appears to be stronger for the low NH3 blend fraction. The chemistry effect of NH3 on soot reduction for C2H4 flame is ascertained by comparing with N2-doped C2H4 flame at the same volume percentage. This work highlights the need for improved understanding of hydrocarbon fuel with NH3 to enable detailed understanding on the soot generation and oxidation process.

The Effects of Different Natural Plant Extracts on the Formation of Polycyclic Aromatic Hydrocarbons (PAHs) in Roast Duck.

Polycyclic aromatic hydrocarbons (PAHs) with high carcinogenicity and mutagenicity may be generated in roast duck during high-temperature roasting. Natural extracts with antioxidant effects may inhibit the formation of PAHs. The objective of this study was to compare the effects of green tea extract (GTE); extract of bamboo leaves (EBL); grape seed extract (GSE) and rosemary extract (RE) on PAHs in roast duck to obtain the optimum extract and present a guidance for reducing PAHs in roast duck. The total phenol content and antioxidant capacity of the four extracts were measured, and the PAH changes in the roast duck caused by the four extracts were detected. The total phenol content of GTE was the highest, 277 mg gallic acid equivalent (GAE)/g, while RE was the lowest at 85 mg GAE/g. The antioxidant capacity of RE was 1.9 mmol Trolox/g, which was significantly lower than that of the other three. The four extracts inhibited PAHs formation in roast duck to varying degrees: When the concentration was 25 g/kg, the best inhibitory effects on Benzo [a] pyrene (BaP) and PAH4 (BaP, BaA, BbF and CHR) were obtained from GTE, with inhibition rates of 75.8% and 79.7%, respectively, while the weakest inhibition rates, 32.7% and 43.6%, respectively, were from RE.

Assessment on combustion chemistry of coal volatiles for various pyrolysis temperatures

Carrying out in-depth research on the formation characteristics and mechanisms of organic products in coal combustion will help to provide theoretical guidance for the emission reduction of coal-fired pollutants. Since the combustion of coal volatiles plays a vital role in the whole process of coal combustion, this work took coal pyrolysis gases as fuels and focused on the organic pollutants such as alkanes, olefins and aromatics in the combustion of coal pyrolysis gases. To explore the effects of three pyrolysis temperatures of 600 °C, 750 °C and 900 °C on the formation characteristics and mechanisms of hydrocarbon products during coal pyrolysis gases combustion, the online detection was carried out by gas chromatography (GC) and gas chromatography-mass spectrometer (GC-MS) on the counterflow diffusion flame platform, combined with chemical reaction kinetics simulations. The results showed that rising pyrolysis temperature had an inhibitory effect on the formation of light hydrocarbons and aromatic hydrocarbons, such as acetylene (C2H2), propyne (PC3H4), 1,3-butadiene (C4H6-13), vinylacetylene (C4H4), diacetylene (C4H2), benzene (C6H6), toluene (C6H5CH3) and naphthalene (C10H8), during the combustion of pyrolysis gases. Among three mechanisms used in this study, Creck mechanism was more accurate and applicable than KM2 mechanism and AramcoMech 3.0 mechanism. As the pyrolysis temperature rose, the rate of the reactions which dominated the formation of C2H2, propargyl (C3H3), C6H6 and C10H8 decreased continuously, because the decrease of CH3 concentration and the increase of H concentration inhibited the forward progress of these reactions. In addition, with rising pyrolysis temperature, less C3H3 was converted to butadiene (C4H6), C6H6 and Fulvene, and more inclined to its upstream reactants, allene (AC3H4) and PC3H4. The tendency of phenyl (C6H5) to form C6H6 was strengthened. Meanwhile, less C10H8 was generated from C4H4 and C6H5, but the dominant role of this reaction was still enhanced.

Low-temperature nitrogen-bearing polycyclic aromatic hydrocarbon formation routes validated by infrared spectroscopy

Polycyclic aromatic hydrocarbons (PAHs) are abundant in many regions of the Universe, representing a major reservoir for cosmic carbon. However, their formation pathways in cold regions of space remain elusive. Recent astronomical detections show that current astrochemical models drastically underestimate the abundance of aromatic molecules and suggest that additional formation pathways such as ion–molecule reactions need to be considered. Here we reveal efficient low-temperature formation pathways towards nitrogen-containing PAHs via exothermic pyridine+ and acetylene ion–molecule reactions. The experimental approach combines kinetics with spectroscopic probing and unambiguously identifies key reaction intermediates and the final nitrogen-containing PAH product quinolizinium+, a structure that is thought to contribute to the 6.2 μm interstellar emission feature. This study not only provides competing formation pathways relevant in the chemistry of the interstellar medium and Titan’s atmosphere, but also delivers information to verify in-silico potential energy surfaces, astrochemical models and infrared observations.

Distinguishing the impact of temperature on iron catalyst during the catalytic-pyrolysis of waste polypropylene

The catalytic pyrolysis of waste plastics with iron-based catalyst can produce H2 rich gas, liquid oil and carbon nanotube (CNTs) together. While the catalytic pyrolysis mechanism is still unclear, in this study, the catalytic pyrolysis of polypropylene (PP) was explored in depth, and the influence of catalyst and temperature was distinguished. The results indicated that a lower temperature led to the generation of waxes, while a higher temperature promoted the formation of aromatic hydrocarbons when plastic pyrolysis was performed without a catalyst. In addition, a large number of carbon deposits, mainly in the form of spheres, were collected when the temperature was over 800 ℃. These carbon spheres originated from the agglomeration of aromatic hydrocarbons. Once catalysts were introduced, a large amount of liquid oil was transferred into carbon deposits at both lower and higher catalytic temperatures, simultaneously, leading to more light gases releasing, like hydrogen. At a lower temperature (≤ 800 ℃), it was mainly CNTs while carbon spheres are the main solid product at higher temperatures (> 800 ℃). In addition, two different mechanisms of CNTs formation were also concluded that the base-growth model dominated the of generation CNTs at 600 °C whereas the CNTs followed the tip-growth model at 800 ℃. The results show that the optimized temperature for the catalytic process should be around 800 o℃ where approximately 35 mmol/gplastic hydrogen, 50% hydrogen efficiency and over 320 mg/gplastic carbon nanotubes (CNTs) were obtained.

Low bioavailability of derivatives of polycyclic aromatic hydrocarbons in biochar obtained from different feedstock

In the last years, there is great progress in the field of studies on the thermal transformation of wastes into valuable materials such as biochar. High-temperature processes, however, are connected with the formation of polycyclic aromatic hydrocarbons (PAHs) with confirmed toxicity. However, during pyrolysis, some derivatives containing oxygen, nitrogen, or sulfur can also be formed. Their toxicity is expected to be higher than parent PAHs. However, the key parameter in the agricultural application of carbonaceous materials is PAHs’ bioavailability. The aim of the presented studies was the determination of the effect of various feedstock (wheat straw (Triticum L.), willow (Salix viminalis), sunflower, residues from softwood and hardwood, sewage sludges, and residues from biogas production) on the formation of PAHs and their derivatives (O-, N-PAHs) in biochar and their bioavailability. The results indicated that the content of total and bioavailable PAHs in obtained biochar was rather low. The concentration of total PAHs in plant-derived biochar reached 57 ± 3 ng g−1 - 181 ± 8 ng g−1, whereas sewage sludge-derived biochar contained from 121 ± 6 ng g−1 to 188 ± 9 ng g−1 of PAHs. The highest concentration of PAHs was noted in biochar obtained from residues from biochar production – up to 202 ± 9 ng g−1. The total concentration of bioavailable PAHs was lower and reached 2–4.45 ng L−1 for plant-derived biochar, 3–40 ng L−1 for sewage sludge-derived biochar. The highest content of bioavailable PAHs was noted in biochar obtained from residues from biogas production: 9–42 ng L−1 indicating that increased attention should be paid to using this type of biochar. Among PAHs derivatives, nitronaphthalene, 1-methyl-5-nitronaphthalene, 1-methyl-6-nitronaphthalene, 9,10-anthracenedione, 4H-cyclopenta(def)phenanthrene, nitropyrene were determined at various levels and their concentrations were from below the limit of detection (LOD) to 28 ng L−1 for plant-derived biochar, 3–16 ng L−1 for biochar obtained from residues from biogas production, and 5–45 ng L−1 for sewage sludge-derived biochar. The content of bioavailable PAHs derivatives was, generally, one order of magnitude lower than parent PAHs derivatives, and reached from below LOD up to almost 1 ng L−1 for plant-derived biochar, from 0.5 to 2 ng L−1 for biochar obtained from residues from biogas production, and from 0.2 to almost 5 ng L−1 for sewage sludge-derived biochar confirming the safety of agricultural usage of biochar.

Effects of Onion Extract and Onion Peel Extract on the Formation of Polycyclic Aromatic Hydrocarbons in Charcoal-Grilled Pork Patties

This study investigated the effects of different concentrations (0.0005, 0.005, 0.05, 0.25, and 0.5%) of onion extract (OE) and onion peel extract (OPE) on the formation of four polycyclic aromatic hydrocarbons (PAHs) in charcoal-grilled pork patties. Both OE and OPE inhibited the formation of four PAHs in charcoal-grilled pork patties, with the highest inhibition rate reaching 88.33% on 0.50% OE addition and 98.79% on 0.05 and 0.25% OPE addition. OPE has greater inhibitory effect on the formation of four PAHs than OE does; this may be related to OPE's higher concentrations of flavonoids and higher free-radical scavenging activities. Both OE and OPE worked to lower thiobarbituric acid reactive substance values of charcoal-grilled pork patties. The inhibitory effect of OE and OPE on four PAHs showed the same trend as their antilipid oxidation effects, but the correlation was not strong. In addition to antilipid oxidation, other pathways are also involved in the inhibition of PAH formation.

Formation of polycyclic aromatic hydrocarbons and regulated emissions from biodiesel and n-butanol blends containing water

To increase the use of biofuels in diesel engines and reduce harmful emissions emitted from diesel fuel, biodiesel and higher alcohols are fuel sources at the forefront of research. The aim of this study is to understand the effect of water-containing n-butanol-biodiesel blends on regulated emissions, emphasizing nitrogen oxides (NOx) and polycyclic aromatic hydrocarbons (PAHs), which are harmful for the environment and engine durability. 10% n-butanol (B90Bu10) and 10% n-butanol-1% water (B89Bu10W1) were blended with 89% waste-oil biodiesel and tested in a diesel engine at four engine loads at a constant engine speed. PAH samples were analyzed using gas chromatography-mass spectrometry (GC-MS). Results showed B100, B90Bu10 and B89Bu10W1 blends increased break specific fuel consumption (BSFC), exhaust gas temperatures (EGT), carbon monoxide (CO) and hydrocarbon (HC) emissions. However, NOx emissions significantly decreased using butanol and butanol-water blends. Compared to diesel, biodiesel and blended fuels significantly reduced total PAHs and PAH toxicity up to 75.0%. However, B89Bu10W1 increased total PAH and PAH toxicity by 35.7%. Overall, the biodiesel-butanol blend, which emits less carcinogenic pollutants and low-cyclic PAHs than water-containing fuel, was found to reduce the risk of wetstacking in diesel engines operating under low loads.

Mitigation of Polycyclic Aromatic Hydrocarbons Formation in Goat Satay by Shallots Juices Marination

This study aimed to mitigate the carcinogen formation of polycyclic aromatic hydrocarbons (PAHs) in charcoal-grilled goat satay by marinating raw goat-satay with shallots (Allium cepa var. Ascalonicum) juices. The experiment used a 2 x 4 split-plot factorial randomized block design. The experiment consisted of 2 treatments of 2 goat satay types (without and with sliced fat) and 4 treatments of marination with shallots juice at concentrations of 0%, 10%, 20%, and 30% (gmL-1 of fresh shallots in distilled water) for 60 minutes at 4 °C. A total of 24 samples of raw and grilled goat-satay were used for 3 replication groups. The marination with 10% and 20% shallots juices significantly reduced the BaP and BaA until they were not detected even though they increased the non-carcinogenic Pyr levels in the grilled goat-satay with and without sliced fat. The marination with 10%, 20%, and 30% shallots juice significantly prevented the formation of Phe, Ace, and Nap so that they were not detected in the grilled goat-satay with and without sliced fat. The marination with 30% shallots juice of raw goat-satay without sliced fat resulted in the highest antioxidant activities and detectable BaP levels (3.88 mg kg-1).

Production of aromatic hydrocarbons by co-cracking of bio-oil and ethanol over Ga2O3/HZSM-5 catalysts

• The activity of Ga 2 O 3 /HZSM-5 was significantly affected by the preparation method. • Weak Brønsted acidity was detrimental to deoxygenation and aromatization reactions. • The catalyst prepared by impregnation showed high activity at a Si/Al ratio of 25. The catalytic cracking of bio-oil is important to produce aromatic hydrocarbons, which can partially replace gasoline or diesel to greatly reduce carbon emissions from transportation. To further promote the formation of aromatic hydrocarbons, this work studied the effects of the preparation method and the acid strength of Ga 2 O 3 /HZSM-5 on catalytic cracking of the bio-oil distilled fraction systematically. The preparation method of Ga 2 O 3 /HZSM-5 had an important effect on its catalytic activity: the Ga 2 O 3 /HZSM-5 prepared by physical mixing showed the low dispersion of active phases and poor pore structure, resulting in its insufficient activity and severe coke deposition; the Ga 2 O 3 /HZSM-5 prepared by precipitation exhibited the higher activity, while many polycyclic aromatic hydrocarbons unfavorable for the subsequent utilization were in the oil phase; the Ga 2 O 3 /HZSM-5 prepared by impregnation showed the highest activity and 35.5% (mass) selectivity of the oil phase, including 80.3% monocyclic aromatic hydrocarbons and 12.0% polycyclic aromatic hydrocarbons. The Brønsted acidity of Ga 2 O 3 /HZSM-5 decreased with Si/Al ratio, leading to the decline in reactant conversion, oil phase selectivity and quality. Meanwhile, the polymerization between monocyclic aromatic hydrocarbons and oxygenates was promoted to produce many polycyclic aromatic hydrocarbons and even coke, causing catalyst deactivation.

Образование и выгорание полициклических ароматических углеводородов в топках котлов

This paper presents the results of the next stage of ongoing author’s research on hazardous emissions from thermal power plants. Environmental safety regulations require utility companies to determine limits of their highly toxic pollutants with oncogenic and mutagenic effects, including polycyclic aromatic hydrocarbons. Such hazardous emissions depend on a fuel type, combustion technique, and combustion process parameters. In this research, the factors of polycyclic aromatic hydrocarbon formation and combustion for boiler furnaces were explored.