Concentrations Of Aliphatic Hydrocarbons Research Articles

Kinetic characteristics and product distribution of tar-rich coal in-situ underground pyrolysis: Influence of heterogeneous coal seam

Tar-rich coal contains more hydrogen-rich structures such as aliphatic side chains and bridge bonds, which is a good raw material for coal to oil. In-situ underground pyrolysis of tar-rich coal has significant advantages such as environmental friendliness and high safety factor; it is an efficient, clean coal utilization technology. Due to the influence of geological structure and other factors in the formation process, underground coal seam was often heterogeneous, generally accompanied by coal gangue interlayers. Due to the coal gangue being relatively dense and has poor thermal conductivity, it is also rich in metal oxides, it would inevitably affect the pyrolysis characteristics and product distribution during the pyrolysis process of heterogeneous tar-rich coal seam. The pyrolysis characteristics of heterogeneous tar-rich coal seam with different positions and layers of coal gangue interlayer were investigated by the thermogravimetric analyzer, and related kinetic parameters were obtained by the distributed activation energy model (DAEM). Based on the fixed bed tube furnace reactor, the pyrolysis experiments of heterogeneous tar-rich coal seam with different positions and layers of coal gangue interlayer were also carried out, and the pyrolysis products were characterized and analyzed. The thermogravimetric results showed that in the pyrolysis process of heterogeneous tar-rich coal seam, the initial pyrolysis temperature and the temperature corresponding to the maximum weight loss rate shifted to the higher temperature range, and the pyrolysis characteristic index decreased significantly. Under the same conditions, the corresponding pyrolysis characteristic indexes of the upper coal gangue interlayer and 4 layers of coal gangue interlayer were lower, which were 11.69 (10−8·%·min−1·℃−3) and 11.65 (10−8·%·min−1·℃−3), respectively. Compared with homogeneous tar-rich coal seam, pyrolysis activation energies of heterogeneous coal seam generally showed the decreasing trend. Under the conditions of the upper part containing coal gangue interlayer and the upper-and-lower parts containing coal gangue interlayer, the pyrolysis activation energies were higher due to the hindrance of the cover layer of coal gangue to the volatile release, which were 555.88 kJ·mol−1 and 546.66 kJ·mol−1 respectively. The results of fixed bed pyrolysis experiments showed that compared with homogeneous tar-rich coal seam, the tar yield obtained was reduced, the degree of tar lightening was significantly improved, and the proportion of lighter tar was up to 70.00 wt%. The contents of aromatic hydrocarbons and phenolic compounds in tar increased, the contents of aliphatic hydrocarbons and oxygenated compounds decreased significantly, and the maximum reductions were nearly 4.50 wt% and 6.50 wt%, respectively. The gas yield increased, the proportions of H2 and CO2 in the gas increased, and the proportions of CO and CH4 decreased to varying degrees. The tar yields were lower under the conditions of upper gangue and 4 layers gangue, which were 6.53 wt% and 5.81 wt%, respectively, and the degrees of tar lightening were also more significant. From the relationship between pyrolysis characteristic parameters and tar properties of heterogeneous tar-rich coal seam pyrolysis, it was found that the existence of coal gangue interlayer was not conducive to the tar production, but it could promote the lightening of tar and improve the tar quality. Exploring the kinetic characteristics and pyrolysis product distribution of heterogeneous tar-rich coal seam could provide theoretical guidance for the site selection of in-situ underground pyrolysis engineering and the well arrangement.

Pore Morphology and Oxidation Behaviour of Deep-Loaded Granular Coal at High Initial Temperatures

ABSTRACT As coal mining proceeds deeper, fragmented coal is subjected to high geostress and elevated thermal environments, causing changes in its micro-physical properties and spontaneous combustion (SC) risks. Deep mining operations entail significant risks of coal fires. In order to investigate the effects of high stress and high thermal environments on the microstructural and physicochemical damage of fragmented coal, and to elucidate the mechanisms influencing oxidation behavior, we conducted experiments including low-temperature nitrogen adsorption, synchronous thermal analysis, and in-situ diffuse reflectance spectroscopy. These experiments aimed to explore the pore morphology and oxidation characteristics of high initial temperature unloading granular coal (HITU-GC) unloading conditions. The results indicate that with increasing initial temperature, characteristic point temperatures initially rise and then decrease, while both the mass loss and heat release during the low-temperature oxidation stage decrease. After pressure-unloading composite treatment, the oxidation process accelerates with more intense reactions, resulting in an overall increase in heat release. The pore shapes of HITU-GC show no significant difference compared to the original coal, mainly comprising non-rigid aggregates of micropores, platy or layered matrix particles, including numerous slit-shaped pores. The coal surface also exhibits ink bottle-shaped pores and cone-shaped pores. Higher pre-oxidation temperatures correlate with higher specific surface areas. Higher stress levels from pressurized unloading correlate with lower specific surface areas. The specific surface area of sample O60-P16 is reduced by 0.879 m2/g compared to sample O60-P0. Pressurized unloading treatment disrupts mesoporous pores. Following thermal environment and pressure-unloading, the coal’s aromatic hydrocarbon content decreases, while the contents of hydroxyl, aliphatic hydrocarbons, and oxygen-containing functional groups (FG) all increase. Sample O60-P4 shows the highest content of active FG. While thermal environments enhance coal oxidation activity, pressure-unloading treatment increases the extent of coal surface fragmentation. The synergistic effect of both significantly increases the SC risk of coal. This study provides a theoretical basis for controlling thermal hazards associated with high-initial-temperature unloading fragmented coal in deep goaf areas.

Determination of the Nature of Hydrocarbons in the Barents Sea (Verification of Remote Sensing Data)

Based on remote sensing data on the distribution of oil spills obtained using synthetic aperture radar (SAR) imagery of the Sentinel-1A and Sentinel-1B satellites in 2016–2022 and the results of the analysis of aliphatic hydrocarbons (AHCs) and polycyclic aromatic hydrocarbons (PAHs) in bottom sediments taken in 2019–2022, the nature of oil slicks in various areas of the Barents Sea has been established. It is shown that the distribution of oil slicks in coastal areas is greatly influenced by anthropogenic hydrocarbon inflow (mainly from shipping and fishing), which is confirmed by elevated AHC concentrations in coastal sediments (up to 73 μg/g) and in the composition of Corg (up to 3.6%). In the central and northern regions of the Barents Sea (station 7105, in the coordinates 75.2–75.3 N, 31.5–31.8 E), the grouping of oil slicks is due to natural seepage of oil and gas. This is confirmed by the anomalous concentration of PAHs in the lower horizons of the obtained sediment column, and their composition (the dominance of 2-methylnaphthalene, a marker of their oil genesis). At the same time, the proportion of light homologues in the composition of alkanes increased, which may indicate their formation in the sedimentary sequence.

Impacts of LNAPL types on mechanisms and rate of natural source zone depletion

Understanding the mechanisms of natural source zone depletion (NSZD) will support an improved understanding of the long-term sustainability of NSZD as a site remedy and how NSZD rates may change over time. This is the first study that has quantified and compared the rate of three NSZD mechanisms (methanogenesis, vaporization, and aqueous biodegradation) between two chemically distinct light non-aqueous phase liquid (LNAPL) source zones (aliphatic-rich naphtha for Zone #1 vs aromatic-rich pyrolysis gasoline for Zone #2) within the same geologic and climate conditions. The rates of NSZD attributable to vaporization (400 mg C/m2/d vs. 300 mg C/m2/d) and aqueous biodegradation (92 mg C/m2/d vs. 67 mg C/m2/d) were similar for Zone #1 and #2; however, the rate of methanogenesis NSZD was 6x higher in Zone #1 (1000 mg C/m2/d vs. 170 mg C/m2/d). These results suggest that the aliphatic hydrocarbons content in an LNAPL source may be a factor in the rate of methanogenesis NSZD. For both Zone #1 and #2, total NSZD rate determined using this “three mechanism” measurement method was in reasonable agreement with two other methods used to measure total NSZD rates (CO2 Gradient Method and Dynamic Closed Chamber Method), validating the “three mechanism” method as a tool to measure the total NSZD rate at a site and to provide an improved understanding of the predominant NSZD mechanism. Overall, this study highlights the importance of LNAPL type and chemical characteristics in determining source zone natural attenuation mechanism and its total rates.

Sequential oxidation-composting-phytoremediation treatment for the management of an oily sludge from petroleum refinery

Oily sludges are generated in large quantities in petroleum refinery wastewater treatment plants. Given their complex composition, they are classified as hazardous waste. Selecting a single treatment technique for their remediation is challenging.This work aims to assess the extent of composting followed by phytoremediation on an oily sludge from an API separator unit, pre-treated by chemical oxidation with alkaline activated persulfate (PS). 18% of total petroleum hydrocarbons (TPH) were determined by IR spectroscopy. The aliphatic hydrocarbon content was 4714 ± 250 ppm by GC-FID, and aromatics were not detectable, suggesting a high amount of non-chromatographable complex hydrocarbons. The density of generalist and hydrocarbon-degrading populations of the oily sludge estimated by quantitative polymerase chain reaction (qPCR) evidenced an autochthonous microbiota with hydrocarbon-degrading capacity. The oxidative treatment with PS removed 31% of the TPH determined by IR after 20 days. The significant reduction of the native bacterial community was counterbalanced by coupling a composting treatment. Co-composting the sludge with goat manure and oat straw produced, after a year, a 96% reduction in TPH content, regardless of the oxidative pretreatment. Organic matter transformation was evidenced by the decrease of dissolved organic carbon (DOC) and the variation in E4/E6 ratio. The matrices obtained of composting were used as substrates for phytoremediation for 4 months. Ryegrass seeds were planted in both PS-treated and untreated sludge substrates. The presence of the plant grown in the pre-oxidised and composted substrate resulted in a higher aerial biomass of ryegrass (67%), an increase in enzymatic activities, and higher concentration of DOC, although without evidence of additional dissipation of TPH.The dynamics of the bacterial communities of the different substrates generated during the biological treatment were analyzed by Illumina NovaSeq DNA sequencing of 16S rRNA amplicons. The findings mirrored a succession compatible with that described in contaminated matrices, but also in other non-contaminated ones.According to these findings, an organic matter transformation process occurred, which included the complex hydrocarbons of the oily sludge, resulting in an active substrate that promoted the retention of nutrients and water and provided the necessary support for plant development.

Autochthonous bioaugmentation strategies for the successful bioremediation of high-salt petrochemical wastewater using a biosurfactant-producing Enterobacter cloacae Z11

Petrochemical wastewater contains a high concentration of refractory aliphatic and aromatic hydrocarbons. Bioremediation of these hazardous materials using autochthonous bioaugmentation (ABA) strategy is attracting increasing interest. Herein, an indigenous biosurfactant-producing bacteria Z11 was isolated and identified as Enterobacter sp. The reintroduction of Z11 into petrochemical wastewater led to a substantial reduction (P < 0.01) in TPHs, decreasing from 8099 to 1723 mg/L, as well as a significant decrease in COD, decreasing from 8064.2 to 1689.2 mg/L. At a critical micelle concentration of 200 mg/L, the biosurfactant synthesized by Z11 exhibited an extraordinary decrease in surface tension from 67.5 to 29 mN/m. The biosurfactant demonstrated favorable surface activity over a wide pH, temperature, and salinity range. Based on a series of chemical analyses, the biosurfactant was classified as phospholipid. The autochthonous bioaugmentation technique developed by Z11 indicated a significant increase (P < 0.05) in the degradation of n-alkanes of varying chain lengths and polycyclic aromatic hydrocarbons. The analysis of the microbial composition demonstrated that the addition of Z11 caused a rise in bacterial populations capable of hydrocarbon decomposition, such as Pseudomonas sp. and Stenotrophomonas sp. The activities of two enzymes involved in degradation, alkane hydroxylase and alcohol dehydrogenase, increased dramatically and showed a significant (P < 0.05) correlation with Enterobacter sp. Z11. The proposed mechanism could be elucidated that functional genes regulate the secretion of biodegradation enzymes and biosurfactants to promote the deep degradation of petroleum hydrocarbons. This study provides technical support for the reintroduction of autochthonous microorganisms capable of producing biosurfactants in implementing in situ ABA strategies.

Yield and distribution of products of lignin liquefaction catalyzed by molybdenum-vanadium-phosphorus heteropolyacids

ABSTRACT This paper focuses on the performance of Molybdenum-vanadium-phosphorus heteropolyacids (PMo12-xVx) with different V-doped amounts in catalyzing the conversion of lignin to bio-oil, and the distribution of liquefied products. Molybdenum-vanadium-phosphorus heteropolyacids (PMo11V1, PMo10V2, PMo9V3) with different amount (0, 2.5, 5, 10 wt%) were used to catalyze lignin liquefaction. The experimental results showed that PMo12-xVx could effectively catalyze the depolymerization of lignin to bio-oil, and the doping amount of the V atom in PMo12-xVx affects the distribution of lignin depolymerization products. The highest bio-oil yield (53.62wt%) and conversion (57.83wt%) could be obtained from lignin liquefaction at 2.5 wt% PMo9V3. With the increase of PMo12-xVx V-atom doped amount, the content of aliphatic hydrocarbons increased from 3.14% to 40.58%, the content of vanillin increased from none to 8.9%. Based on the analysis of bio-oil, FT-IR data, and DFT simulation results, it was found that the selective cleavage of the Cα-Cβ bond and the ring-opening of the carbon at the methyl end of lignin were the main reasons for the high yield of vanillin and aliphatic hydrocarbons during the depolymerization of lignin catalyzed by PMo12-xVx. Finally, a possible reaction pathway for the PMo12-xVx-catalyzed depolymerization of lignin to vanillin and aliphatic hydrocarbons was proposed.

Occurrence, Distribution, and Sources of Aliphatic and Cyclic Hydrocarbons in Sediments from Two Different Lagoons along the Red Sea Coast of Saudi Arabia

Surface sediment samples from Al-Qahma lagoon in the southern part and Al-Wajh lagoon in the northern part of the Red Sea coast of Saudi Arabia were collected by a Van Veen grab sampler to determine the characteristics, distribution, and sources of aliphatic and cyclic hydrocarbons. The total extractable organic matter (TEOM) was extracted with a dichloromethane/methanol mixture after drying and sieving the sediments and identified by gas chromatography–mass spectrometry. The TEOM comprised n-alkanes (302.6 ± 446.7 ng·g−1 and 64 ± 50 ng·g−1), hopanes (29.8 ± 132.3 ng·g−1 and 1.0 ± 2.5 ng·g−1), steranes (0.0 and traces), n-alkanoic acids (745.8 ± 799.6 ng·g−1 and 120.7 ± 92.0 ng·g−1), n-alkanols (457.4 ± 1085.6 ng·g−1 and 49.7 ± 32.3 ng·g−1), polycyclic aromatic hydrocarbons (PAHs) (54.5 ± 96.8 ng·g−1 and 7.8 ± 8.5 ng·g−1), and phthalates (185.3 ± 169.9 ng·g−1 and 67.4 ± 70.4 ng·g−1) in the Al-Qahma and Al-Wajh lagoon sediments, respectively. The percentages of the various sources relative to total aliphatic and cyclic hydrocarbon concentrations were 6.9 ± 6% for terrestrial plants, 53.7 ± 19% for algae, 10 ± 2% for microbial, 16 ± 12% for petroleum, and 13.4 ± 7 for plasticizer inputs in Al-Qahma lagoon. In Al-Wajh lagoon, they were 9.7 ± 4% for terrestrial plants, 30.8 ± 14% for algae, 25.2 ± 5% for bacteria, 11.2 ± 3% for petroleum, and 23.1 ± 11% for plasticizers.

Experimental study on the effect of room temperature pre-oxidized time on spontaneous combustion characteristics of coal

The presence of different types of coal at room temperature can lead to self-heating of coal, potentially resulting in spontaneous combustion. To investigate the effect of ambient temperature pre-oxidation (BL) time on the self-combustion characteristics of different coal types, synchronous thermal analysis (STA) and Fourier-transform infrared spectroscopy (FTIR) experiments were conducted. The results of the synchronous thermal analysis experiments indicate that ambient temperature pre-oxidation for 3 months (BL3), BL6, and BL9 coals exhibit faster oxidation reactions compared to the original coal, while BL12 coal shows slower oxidation than the original coal. Among these, BL9 coal demonstrates the most significant changes in oxidation reaction characteristics, with the fastest oxidation reaction time being 35.36 min, which is 1.38 min faster than the original coal. To support this observation, a comparison was made between the relative content of active functional groups in the original coal and BL coal. The study revealed that the BL process affects the relative content of hydroxyl groups, aromatic hydrocarbons, aliphatic hydrocarbons, and oxygen-containing functional groups, thereby influencing the coal-oxygen reaction process. This suggests that pre-oxidized coal, compared to the original coal, has a larger pore structure, which plays a dominant role in promoting coal self-combustion in the first 9 months of the BL process. As BL time continues to increase, the continuous reaction of active functional groups at room temperature leads to excessive consumption, resulting in a more significant role in inhibiting coal self-combustion. The research results provide valuable insights for predicting the spontaneous combustion risk of oxidized coal.

Changes in the nature of organic matter in a large tropical urban bay: Temporal variations and environmental implications

We used information on the elemental (C/N ratio), isotopic (δ13C and δ15N) and molecular (aliphatic hydrocarbons) composition of organic matter in sediments from two cores collected in the Todos os Santos Bay to investigate the sources, distribution and fate of organic matter (OM). TOC (0.66–2.23%) and TN (0.12–0.26%) concentrations increased over time but still indicate an oligotrophic system. A simple isotopic mixing model shows a mixture of sources, with autochthonous OM dominating (47.1–93.2% of TOC). ALCTOT concentrations in the sediments varied from 0.25 to 5.84 µg g−1. The ACL (27.79–29.89) and AI (0.02–0.57) indices show the dominance of the terrestrial contribution coming from C3 vascular plants, such as the mangrove vegetation present on the BTS tidal flats. In core T2, collected at a more offshore site, the parameters analyzed indicate better environmental conditions with natural sources of hydrocarbons. At the T4 core collection site, which was close to the shoreline, a gradual and persistent increase in terrestrial input from 1950 onward was detected, probably related to changes in land use. From 1980 onward, a clear petrogenic signature is seen with the presence of a complex unresolved mixture (nd to 349.94 µg g−1) and increased concentrations of total resolved aliphatic hydrocarbons (0.35–380.34 µg g−1) and normal alkanes (0.25–5.84 µg g−1). Three decades of moderate chronic contamination are revealed in the T4 core, reflecting the history of economic development of the region, including extraction, refining, transportation and burning of fossil fuels and changes in land use. The effects of implementing environmental policies to improve the Bay's water quality began to be reflected in the sediment quality at the beginning of the 21st century.

Simulation and Experimental Study of Solid-Liquid Extraction of Coal Tar Residue Based on Different Extractants.

Coal tar residue (CTR) is recognized as a hazardous industrial waste with a high carbon content and coal tar consisting mainly of toxic polycyclic aromatic hydrocarbons (PAHs). The coal tar in CTR can be deeply processed into high-value-added fuels and chemicals. Effective separation of coal tar and residue in CTR is a high-value-added utilization method for it. In this paper, ethyl acetate, ethanol, and n-hexane were chosen as extractants to study the extraction process of coal tar from CTR, considering the mass transfer in the liquid phase outside the CTR particles and the diffusion inside the CTR particles, and a mathematical model of the solid-liquid extraction process of CTR was established based on Fick's second law. First, the mass-transfer coefficients (kf) and effective diffusion coefficients (De) of ethyl acetate, ethanol, and n-hexane in solid-liquid extraction at 35 °C were determined to be 1.54 × 10-5 and 4.99 × 10-10 m2·s-1, 1.14 × 10-5 and 3.57 × 10-10 m2·s-1, and 1.01 × 10-5 and 3.48 × 10-10 m2·s-1, respectively. Furthermore, the simulated values obtained by the model also maintained a high degree of agreement with the experimental results, which indicates the high accuracy prediction of the model. Finally, the model was used to investigate the effects of the solvent-solid ratio, temperature, and stirring speed on the extraction rates with the three extractants. According to the analysis with gas chromatography-mass spectrometry (GC-MS), among the three solvents, n-hexane extracted the highest content of aliphatic hydrocarbons (ALHs), ethyl acetate extracted the highest content of oxygenated compounds (OCs), and ethanol extracted the highest content of aromatic hydrocarbons (ARHs). The model and experimental data can be used to provide accurate predictions for industrial utilization of CTR.

Evolution and oxidation properties of the functional groups of coals after water immersion and air drying

The evolution of functional groups, the gas generation laws in oxidation and temperature increase, and the oxidation kinetics parameters of the coal samples immersed in water for 30 days, 90 days, and 150 days (hereinafter referred to as 30 d coal, 90 d coal, and 150 d coal, respectively) were analyzed through Fourier transform infrared spectrometer, programmed temperature increase test system, and thermal gravimetric analyzer to disclose spontaneous combustion and the influencing mechanism of long-flame coals immersed in water for a long period. Results show that the aliphatic hydrocarbon and the hydroxyl contents of the coal samples increase after water immersion and air drying. In particular, the aliphatic hydrocarbon contents in 30 d coal, 90 d coal, and 150 d coal increase from 12.61 % for raw coal to 15.84 %, 14.08 %, and 13.90 %, respectively, whereas the hydroxyl content increases from 48.75 % for raw coal to 50.77 %, 50.13 %, and 49.23 %, respectively. In the low-temperature oxidation process, the CO output increases, and the apparent activation energy declines. When the temperature is 200 °C, the CO outputs of 30 d coal, 90 d coal, and 150 d coal are 28088, 25421, and 22112 ppm, which are 37.4 %, 24.4 %, and 8.2 % higher than the CO output of raw coal (20437 ppm), respectively. The apparent activation energy decreases from 65.7 kJ mol−1 for raw coal to 61.12 kJ mol−1, 63.08 kJ mol−1, and 64.5 kJ mol−1. According to the comparison of characteristic temperature points, the temperature of the mass extreme (T3) and the temperature of ignition point (T4) of the immersed coal samples both decrease. The T3 values of 30 d coal, 90 d coal, and 150 d coal decrease from 282.71 °C for raw coal to 274.87, 278.33, and 280.50 °C, whereas their T4 values decrease from 424.24 °C for raw coal to 419.23, 420.14, and 423.42 °C, respectively. This study proves that water immersion increases the oxidative activity of coals, thereby simplifying spontaneous combustion.

Petroleum-like fuels with substantially enriched branched iso-paraffins and benzenes via boehmite-assisted pyrolysis of oil shale

Oil shale (OS) is a potential alternative to substitute/supplement traditional fossil fuels, where catalyst-assisted OS pyrolysis has become a subject of general concern. While great progresses have been realized in this field, the pursuit of high-performance catalysts for a niche OS utilization still remains a formidable challenge, because most of the catalysts face various problems, including, high cost, unsatisfactory performances, etc. Based on a two-stage flash pyrolysis, we herein report our efforts about this issue by using boehmite, a low-cost industrially relevant material of an easy availability, as catalyst. We show that boehmite could arouse 17.0 % decreases in activation energy of OS pyrolysis. When the pyrolysis is executed at the 1st stage (450 °C), the content of hydrocarbons and short-chain aliphatic hydrocarbons (≤C13), which are desired for petroleum-like fuels (PLFs), increases evidently by 56.73 % and 158.5 %, respectively, while that of heteroatomic compounds and long-chain aliphatic hydrocarbons (≥C20), which are undesired for PLFs, decreases distinctly by 60.09 % and 41.6 %, respectively, indicating an evident improvement in the quality of the pyrolysates. Fascinatingly, the content of branched iso-paraffins, especially, monomethyl-, dimethyl- and trimethyl-branched paraffins, which are either efficient octane number boosters, important tectons for functional surfactants, or significant component for high-quality fuels of excellent low-temperature performances, increases substantially by ca. 180.2 % from ca. 16.02 % to 44.89 %. For the 2nd stage at 585 °C, besides a distinctly improved quality of the pyrolysates, the content of benzene, toluene, xylene and trimethylbenzene, which are value-added chemicals broadly employed in numerous industrial fields of paramount importance, is enriched distinctly by 94 %, 65.2 %, 13 %, and 19 %, respectively. We find that the concentration of the Brönsted acid sites (BASs) of the employed boehmite, which contain 94 % medium and strong BASs, is substantially lower than that of Lewis acid sites (LASs), which contain merely 54.91 % medium and strong LASs, such that the competitive-collaborative actions of BASs and LASs confer boehmite with outstanding catalytic reactivity.

Evaluation of the Contents of Aliphatic and Aromatic Hydrocarbons in Sediment from Zwitina Harbor Coast (Libya), as Indicator of Petroleum Pollution

Evaluation of the Contents of Aliphatic and Aromatic Hydrocarbons in Sediment from Zwitina Harbor Coast (Libya), as Indicator of Petroleum Pollution

Synthesis of Ni/Clinoptilolite catalyst by modified polyol method for upgrading of bio-oil produced from hazelnut husk pyrolysis

Bio-oil obtained by pyrolysis of biomass contains high amounts of oxygenated compounds as a result its physicochemical properties may give rise to certain challenges. Zeolite-based catalysts, such as clinoptilolite, have the ability to convert oxygenated compounds into less oxygenated compounds.10%Ni/Clinoptilolite catalyst was synthesized by modified polyol method as an alternative to known methods instead of common catalysts to improve bio-oil quality. Catalyzed/uncatalyzed pyrolysis of hazelnut husk (HH) was conducted for two distinct retention times (15 s and 25 s) and two catalyst/biomass ratios (1:1 and 2:1) to determine the effect of the catalyst. The optimal catalyst/biomass ratio for obtaining the highest aromatic hydrocarbon content was found to be two, whereas the highest aliphatic hydrocarbon content was observed at a ratio of one. An increase in retention time from 15 s to 25 s was found to have a positive impact on the composition of bio-oil, whereas it decreased the aromatic hydrocarbon content only when the ratio of catalyst to biomass was two.

Investigation on DOPO as reactive fumes suppressant to reduce the fumes emission of asphalt

Asphalt fumes released during pavement construction posed a threat to human health and environment. In this study, 9,10-dihydro-9-oxa-10-phosphorophenanthrene-10-oxide (DOPO) was used as a reactive fumes suppressant to reduce the asphalt fumes emission. The volatilization behavior of DOPO modified asphalt (DOPO-Asphalt) was investigated through thermogravimetric analysis, volatility test and thermal destruction gas chromatography mass spectrometry, and effect of DOPO on the chemical structure and composition of asphalt was explored through nuclear magnetic resonance hydrogen spectroscopy, Fourier transform infrared spectroscopy, and asphalt component testing. The results indicated that 1.0 wt% DOPO reduced the fume content of control asphalt by 1.1% from 120 ℃ − 200 ℃ and the H2S and VOC content by 96.9% and 84.2%, respectively, at 180 ℃. Moreover, 1.0 wt% DOPO reduced the content of aliphatic hydrocarbons, hydrocarbon derivatives, aromatics, and sulfides in control asphalt fumes by 86.8%, 89.7%, 90.7%, and 93.5%, respectively, which may be attributed to electrophilic and nucleophilic reactions between DOPO and volatile substances in asphalt. Chemical structure and composition changing of DOPO-Asphalt confirmed that P-H bond in DOPO was chemically reacted with components in asphalt, generating stable aromatic hydrocarbons and resins. The results provided a novel method for inhibiting the volatilization of harmful substances in asphalt.

Effect of Solvent Treatment on the Composition and Structure of Santanghu Long Flame Coal and Its Rapid Pyrolysis Products.

Easily soluble organic components in Santanghu long flame coal (SLFC) from Hami (Xinjiang, China) were separated by CS2 and acetone mixed solvent (v/v = 1:1) under ultrasonic condition, and the extract residue was stratified by carbon tetrachloride to obtain the light raffinate component (SLFC-L). The effect of solvent treatment on the composition and structure of the coal and its rapid pyrolysis products was analyzed. Solvent treatment can reduce the moisture content in coal from 9.48% to 6.45% and increase the volatile matter from 26.59% to 28.78%, while the macromolecular structure of the coal changed slightly, demonstrating the stability of coal's complex organic structure. Compared with raw coal, the relative contents of oxygen-containing functional groups and aromatic groups in SLFC-L are higher, and the weight loss rates of both SLFC and SLFC-L reached the maximum at about 450 °C. In contrast, the loss rate of SLFC-L is more obvious, being 33.62% higher than that of SLFC. Pyrolysis products from SLFC at 450 °C by Py-GC/MS are mainly aliphatic hydrocarbons and oxygenated compounds, and the relative contents of aliphatic hydrocarbons decreased from 48.48% to 36.13%, while the contents of oxygenates increased from 39.07% to 44.95%. Overall, the composition and functional group in the coal sample were changed after solvent treatment, resulting in a difference in the composition and distribution of its pyrolysis products.

Experimental study on effect of mudstone on spontaneous combustion of coal

The influence of mudstone on the spontaneous combustion of coal was investigated in this study. The effects of different proportions of mudstone on the characteristic temperature, thermal effect, thermal physical parameters, and combustion characteristic index of coal were analyzed by TG-DSC experiments and thermal physical parameter test experiments. The catalytic mechanism of mudstone on the active structure of coal oxidation was obtained by Fourier transform infrared spectroscopy. The results showed that an interaction exists between coal and mudstone, and different stages had different effects. The combustion characteristic index showed a trend of an initial increase followed by a decrease. The thermal conductivity and thermal diffusivity of MY-1 samples were larger than those of raw coal samples, indicating that a small amount of mudstone had the most obvious effect on coal combustion and played a promoting role in the heat transfer of coal samples. The carbon content of mudstone was much lower than that of coal, and the content of metals and their oxides and sulfides was higher. The content of aliphatic hydrocarbons and hydroxyl groups in the samples mixed with mudstone decreased. When coal coexists with a small amount of mudstone, the risk of spontaneous combustion of coal increases.

Study on the thermal kinetics and microscopic characteristics of oxidized coal.

Revealing the characteristics of spontaneous combustion and re-combustion of oxidized coal is of great significance for the coal fire prevention and control. Synchronous Thermal Analyzer (STA) and Fourier Transform Infrared Spectrometer (FTIR) were used to measure the thermal kinetics and microscopic characteristics of coal samples with different oxidation degrees (unoxidized, 100 ℃, 200 ℃ and 300 ℃ oxidized coal). It is found that the characteristic temperatures decrease first and then increase with the increasing degree of oxidation. The ignition temperature of 100 ℃-O coal (oxidized at 100 ℃ for 6h) is relatively the lowest at 334.1 ℃. Pyrolysis and gas-phase combustion reactions dominate the weight loss process, while solid-phase combustion reactions are relatively minor. The gas-phase combustion ratio of 100 ℃-O coal is the highest at 68.56%. With the deepening of coal oxidation degree, the relative content of aliphatic hydrocarbons and hydroxyl groups gradually decreases, while that of oxygen-containing functional groups (C-O, C = O, COOH, etc.) increases first and then decreases, reaching the highest value of 42.2% at 100 ℃. Moreover, the 100 ℃-O coal has the minimum temperature at the point of maximum exothermic power of 378.5 ℃, the highest exothermic power of -53.09 mW/mg and the maximum enthalpy of -18,579J/g. All results show that 100 ℃-O coal has the highest risk of spontaneous combustion than the other three coal samples. This suggests that there is a maximum point of spontaneous combustion risk in the range of pre-oxidization temperatures of oxidized coal.

Spontaneous Combustion Characteristics and Inhibition of Air-Dried Coal with Varying Water Soaking Times

ABSTRACT Coal left in the goaf is prone to oxidation reactions when soaked in water and air-dried, which can cause a temperature increase and potentially lead to a mine fire. The spontaneous combustion characteristics of residual coal soaked in the goaf differ significantly from those of dry coal. Analyzing the variation rules of functional groups in coals with different water soaking times (WSTs) during low-temperature oxidation and exploring the inhibitory effect of an inhibitor on coals with different WSTs are vital in preventing and controlling fires in soaked and air-dried coal seams in the goaf. This paper analyzes the variation rules of functional groups in raw coal samples and samples soaked for one, three, and five months, as well as the corresponding samples under the influence of the inhibitor, MgCl2, using an experimental system of coal low-temperature oxidation and a Fourier transform infrared spectrometer. The following findings were obtained: as the WST increases, the aliphatic hydrocarbon content increases, the low-temperature oxidation activity becomes higher, and the inhibition effect of the inhibitor weakens gradually. As the WST increases, the -CH2, -CH3, -OH, and -COOH contents fall gradually, while the C=O content rises. At the beginning of the oxidation temperature rise (30–70°C), the inhibitor, MgCl2, slows down the consumption of oxygen-containing functional groups and aliphatic hydrocarbon functional groups. However, when the temperature exceeds 130°C, its inhibitory effect on coal oxidation weakens gradually. In this case, a growing number of functional groups are involved in coal oxidation, and the inhibitor fails to effectively prevent coal oxidation. Therefore, it is necessary to strengthen temperature monitoring in the goaf and regularly replenish inhibitors in soaked and air-dried coal seams to enhance the inhibitory effect and prevent the SC of such seams.