Aromatic Content Research Articles

Historical Variation in Carbon Fractions in Permafrost Peatland and Its Effects on Peatland Carbon Pool

ABSTRACTPermafrost peatlands store high amount of soil carbon. These developed on permafrost layers, which are being endangered increasingly by climate change and wildfires. However, limited data exist on the variation in carbon fractions and their effects on the stability of permafrost peatland carbon pools, despite that carbon fractions are widely used in other ecosystems. Here, we considered that peat soils consist of undecomposed plant litter and separated these into five carbon fractions: macro plant residue carbon (MPRC), coarse particulate organic carbon (cPOC), free particulate organic carbon (fPOC), occluded particulate organic carbon (oPOC), and mineral‐associated organic carbon (MAOC). We analyzed the historical variation in these fractions over the past 700 years and their effects on the carbon pool in the Hongtu peatland (HT, northern Great Khingan Mountains, China). Our results showed that MPRC comprised 66.7% ± 7.6% of the carbon pool, whereas oPOC and MAOC accounted for less than 1%. Notably, fPOC, which represented 15.6% ± 6.5% of the total carbon, had a high aromatic content. It may serve as an important stable carbon fraction for the peatland carbon pool. Over the past 700 years, the decrease in proportion of MPRC and increase in proportions of cPOC and fPOC have resulted in significant increases in both carbon content and aromaticity. Warm/dry conditions and high‐intensity fires reduced the accumulation rates (ARs) of MPRC while increasing those of fPOC and cPOC. The high organic carbon content in the HT peatland limited the availability of mineral elements and resulted in MAOC ARs of approximately 0.01 g m−2 yr−1. This was strongly influenced by the regional dust deposition. Cold climates and intense fires caused an increase in dust deposition, which also increased the MAOC ARs.

Research on the Correlation Between the Chemical Components and the Macroscopic Properties of Asphalt Binder

The chemical composition of asphalt binder is closely related to its macroscopic properties, and as an important road building material, its performance directly affects the service performance of asphalt binder pavement. Saturate, aromatic, resin, and asphaltene are the four most common chemical components of asphalt binders, collectively known as the SARA components. The SARA components are used to establish the corresponding relationship between the chemical composition and the macroscopic properties of asphalt binder, which is of great significance for further research on and development of high-performance asphalt pavement materials. This study used eight types of virgin asphalt binders as raw materials, labeled A–H. Firstly, the thin-layer chromatography–flame ionization detection (TLC-FID) method was used to test the SARA contents of the different asphalt binders. Then, the conventional, rheological, and low-temperature properties of the different binders were tested. Finally, gray relational analysis (GRA) and Pearson correlation analysis (PCA) were used to study the correlation between the asphalt binder’s SARA content and its macroscopic properties. The results indicate that the contents of asphaltenes and resins are crucial in determining the high-temperature performance of asphalt binder. By adjusting the ratio of these components, the high-temperature performance of asphalt binder can be optimized. An increase in the content of heavy components, particularly asphaltenes, negatively affects the low-temperature performance of asphalt binder. In contrast, a higher aromatic content enhances its low-temperature performance.

Polycyclic Aromatic Hydrocarbon Contents in Soil Organic Matter Fractions Along an Elevation Gradient in the French Alps

ABSTRACTPolycyclic aromatic hydrocarbons (PAHs) are ubiquitous persistent organic pollutants that accumulate in soils because of their high affinity for soil organic matter (SOM). As these pollutants are toxic to humans and the environment, a better understanding of their fate in the environment is required. This study aimed to assess the PAH distribution within soils according to different soil fractions: the free particulate organic matter (fPOM), the occluded particulate organic matter (oPOM) and the mineral‐associated organic matter (MaOM). PAH contents were measured in bulk soils and SOM fractions of alpine soils along an elevation gradient in the French Alps (Lautaret) from 1920 m to 2840 m a.s.l. A specific PAH distribution was identified, with highest PAH contents in the oPOM, followed by the fPOM, then the MaOM. Organic matter (OM) contents of each fraction can partly explain this distribution, but results of nuclear magnetic resonance (NMR) spectroscopy on fPOM and oPOM also highlighted a correlation between the PAH contents and the degree of decomposition of SOM. This indicates that the PAH distribution may be linked to the formation and transformation of fractions: (i) PAHs in the fPOM correspond to relatively recent deposits and mainly reflect the background contamination, (ii) in the oPOM are the PAHs that resist biodegradation during the transformation of fPOM into oPOM and accumulate in the oPOM; this accumulation may be further enhanced by the formation of aggregates. Finally, (iii) in the MaOM, the lower PAH contents can be explained by the different formation pathway of this fraction and its high degree of decomposition. As the PAH distribution may have an impact on their dynamics in soils, it should be taken into consideration in future research.

Effect of organic supplement on the poly aromatic hydrocarbon content of a crude oil polluted soil

Effect of organic supplement on the poly aromatic hydrocarbon content of a crude oil polluted soil

Photic versus aphotic production of organohalogens from native versus invasive wetland plants-derived dissolved organic matter.

The aphotic formation of natural organohalogens (NOHs) remains inadequately understood, in contrast to the well-documented photo-halogenation process of dissolved organic matter (DOM), despite the significant biogeochemical implications associated with NOHs. This study investigates the differences in the formation of chlorinated and brominated compounds from the photochemical and aphotic reactions of native Phragmites australis (PA-DOM) and invasive Spartina alterniflora (SA-DOM). The findings indicate that SA-DOM exhibits a greater potential for photochemical halogenation, attributed to its higher aromatic content and enhanced photostability. Utilizing advanced mass spectrometry, the study identifies nitrogen-containing and free saturated compounds as primary precursors for both types of DOM during photochemical halogenation. Notably, significant disparities in the halogenation processes of lignin/CRAM, nitrogen-containing/free saturated compounds, and amino sugars between SA-DOM and PA-DOM are observed, leading to a higher production of NOHs in PA-DOM during aphotic reactions compared to photic reactions, even in artificial seawater. Furthermore, the study emphasizes the critical role of dissolved oxygen in the formation of NOHs from PA-DOM under aphotic conditions. Given the rapid fluctuations in oxygen levels, salinity, and solar intensity, alongside tidal and diurnal cycles, the significance of both photic and aphotic pathways for NOHs formation should not be overlooked.

High performance polyurethanes derived from aromatic acetal-containing polyols enabling closed-loop recycling

Acetal-containing polyols with high aromatic content were utilized for the preparation of high performance recyclable polyurethanes. These materials were depolymerized using a novel recycling strategy, enabling the recovery of the monomers.

Pasteurization and the Potential Anti-Obesity Function of Fermented Beverages: A Significant Increase in Nitrogen-Containing Aromatic Heterocyclic Compound Content

Obesity is a chronic disease that profoundly impacts human health, and the role of plant-based formulas (PBFs) in combating obesity has garnered significant interest. Studies have revealed that fermentation significantly enhances the taste, aroma, quality, and health benefits of PBF water extract, with pasteurization being the preferred sterilization technology. However, few studies have investigated the effects of pasteurization on the active components and potential functions of PBF water extract fermentation broth. To examine the impact of pasteurization on fermented water extract of Millettia speciosa Champ (FH08F) and its potential anti-obesity properties, the components of FH08F and thermal-pasteurized FH08F (FH08FS) were analyzed in this study. The analysis revealed a substantial rise in ester content following sterilization. This can be attributed to the acidic environment that promotes the esterification reaction during the heating phase. Network pharmacology was employed to thoroughly examine seven active components of upregulated compounds (URCs) with potential obesity targets, which constituted 92.97% of the total URC content, and four of them were nitrogen-containing aromatic heterocyclic compounds (NAHCs), which accounted for 90.33% of the total URC content. Upregulated NAHCs appear to actively contribute to efficacy against obesity. Molecular docking analyses have shown that theophylline, an NAHC, has the strongest binding affinity with the obesity-related target PTGS2 (Prostaglandin G/H synthase 2, 5FLG). These results imply that theophylline may directly activate PKA/PKG-mediated phosphorylated hormone-sensitive lipase (p-HSL), thereby promoting lipolysis through the cAMP signaling pathway and stimulating the catabolism of triglycerides (TGs) to combat obesity. In conclusion, pasteurization substantially alters the composition of FH08F, and NAHCs are likely to play a significant role in its potential anti-obesity function. These findings provide a scientific foundation for the potential therapeutic effect of FH08FS on obesity and associated metabolic diseases.

Improvement of Engine Combustion and Emission Characteristics by Fuel Property Modulation

The sustainability of diesel engines has come to the forefront of research with the growing global interest in reducing greenhouse gas emissions and improving energy efficiency. The aim of this paper is to support the goal of sustainable development by improving the volatile properties of diesel fuel to promote cleaner combustion in engines. In order to study the effect of diesel fuel volatility on spraying, combustion, and emission, the tests were carried out with the help of the constant volume chamber (CVC) test rig and an engine test rig, respectively. CVC test: A high-speed video camera recorded the spray characteristics of different volatile fuels in a constant-volume combustion bomb. The effects of different rail pressures and ambient back pressures on the spray characteristics were investigated. Engine test: The combustion and emission characteristics of different volatile diesel fuels under different load conditions (25%, 50%, 75%) were investigated in a four-stroke direct-injection diesel engine with the engine speed fixed at 2000 rpm. The test results show that as the rail pressure increases and the ambient pressure decreases, the spray characteristics of the fuels tend to increase; for the more volatile fuels, although reducing the spray tip penetration, the spray projected area and spray cone angle increase, which is conducive to improving the homogeneity of the fuel and air mixing in the cylinder. The improvement of fuel volatility can form more and better-quality mixtures within the ignition delay time (ID), resulting in a 1–2% increase in peak cylinder pressure and a 2–4% increase in peak heat release. For different loads, pre-injection heat release is generated to redefine the ID and combustion duration (CD). Improved fuel volatility effectively reduces carbon monoxide (CO) emissions by about 8–10% and hydrocarbon (HC) emissions by about 13–16%, but it increases nitrogen oxide (NOx) emissions by about 8–11%. Analyzing from the perspective of particulate matter (PM), combined with the aromatic content of volatile fuels, it is recommended to use fuels with moderate volatility and aromatic content under low load conditions, and at medium to large loads, the volatility of the fuel has less weight on particulates and more weight on aromatics, so it is desirable to use the fuel with the lowest volatility and lowest aromatic content of the fuel selected.

Insight into the Amelioration Effect of Nitric Acid-Modified Biochar on Saline Soil Physicochemical Properties and Plant Growth.

Soil salinization is a major factor threatening global food security. Soil improvement strategies are therefore of great importance in mitigating the adverse effect of salt stress. Our study aimed to evaluate the effect of biochar (BC) and nitric acid-modified biochar (HBC) (1%, 2%, and 3%; m/m) on the properties of salinized soils and the morphological and physiological characteristics of pakchoi. Compared with BC, HBC exhibited a lower pH and released more alkaline elements, reflected in reduced contents of K+, Ca2+, and Mg2+, while its hydrophilicity and polarity increased. Additionally, the microporous structure of HBC was altered, showing a rougher surface, larger pore size, pore volume, specific surface area, and carboxyl and aliphatic carbon content, along with lower aromatic carbon content and crystallinity. Moreover, HBC application abated the pH of saline soil. Both BC and HBC treatments decreased the sodium absorption rate (SAR) of saline soil as their concentration increased. Conversely, both types of biochar enhanced the cation exchange capacity (CEC), organic matter, alkali-hydrolyzable nitrogen, and available phosphorus and potassium content in saline soils, with HBC demonstrating a more potent improvement effect. Furthermore, biochar application promoted the growth-related parameters in pakchoi, and reduced proline and Na+ content, whilst increasing leaf K+ content under salt stress. Biochar also enhanced the activity of key antioxidant enzymes (superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)) in leaves, and reduced hydrogen peroxide (H2O2) and malondialdehyde (MDA) content. Collectively, modified biochar can enhance soil quality and promote plant growth in saline soils.

Utilization of Metal-Functionalized ZSM-5 for Methanol and Low-Carbon Hydrocarbon Coupling Aromatization

Aromatics assume a paramount role as indispensable organic chemical feedstock within diverse industrial domains. Simultaneously, the global aromatics market is scarce, particularly with the exorbitant demand for high-value aromatics. Generating aromatics via coal-based methanol and low-carbon hydrocarbon coupling reactions has become a novel green and sustainable development trajectory. In this study, HZSM-5 catalysts featuring different Si/Al ratios and active metal-functionalized modifications were utilized to explore the aromatization effect in light of the Si/Al ratio, types of active components, and metal-loading content in a fixed-bed reactor. The outcomes were that the conversion ratios for methanol and n-pentane attained 99.9% and 83.1%, respectively. Remarkably, an oil phase yield of 32.1% was accomplished, along with an aromatic content of approximately 74.2%, while xylene selectivity reached approximately 37.6% for the 1.0%-ZnO/ZSM-5 (50) catalyst. Ultimately, a reaction mechanism for the coupling of methanol and n-pentane to yield aromatics using a 1.0%-ZnO/ZSM-5(50) catalyst is postulated.

Production of MAH-Rich bio-oil from co-pyrolysis of biomass and plastics using carbonized MOF catalysts under microwave irradiation

This study investigates the effects of various carbonized MOF catalysts on the properties of products derived from microwave-assisted co-pyrolysis of biomass and plastics. The Cr@C catalysts were prepared from MIL-101(Cr) precursors at different microwave carbonization temperatures, while Fe/Cr@C catalysts were synthesized under varying Fe loadings. Characterization of the catalysts was performed using XRD, BET, and FT-IR. The distribution of solid, liquid, and gaseous products, as well as the composition of bio-oil and syngas, were analyzed. The results show that the 5Fe/Cr@C catalyst achieved the highest pyrolysis gas yield (33.05 wt%), while the 15Fe/Cr@C catalyst produced the highest hydrogen yield (24.97 vol%). The Cr@C catalyst promoted hydrocarbon production, with Cr@C-700 achieving a total hydrocarbon content of 51.04%. The incorporation of Fe enhanced the selectivity of Cr@C catalysts for monocyclic aromatic hydrocarbons(MAHs) in the bio-oil. The aromatic content reached a maximum of 19.88% with the 15Fe/Cr@C catalyst. Notably, the MAHs content in the 5Fe/Cr@C catalyst accounted for 97.1% of the total aromatic hydrocarbons. This research provides valuable insights into the potential of carbonized MOF catalysts for producing bio-oil rich in single-ring aromatic hydrocarbons from microwave-assisted co-pyrolysis of biomass and plastics.

In-situ formation of molybdenum disulfide nanoparticle and its catalytic performance in heavy oil long-term aquathermolysis

Heavy oil is an important unconventional petroleum resource due to its abundant reserve, but the reduction of viscosity is a prerequisite for its effective exploitation. Researchers are trying to develop heavy oil catalytic aquathermolysis technologies for their merit of irreversible viscosity reduction through in-situ upgrading. The key point of catalytic aquathermolysis is the in-situ formation of high active catalytic phase. In this study, we have demonstrated that the precursor (NH4)2MoS4 was fully decomposed into MoS2 nanoparticles at relatively low temperature of 200°C after 90 minutes. The decomposition of (NH4)2MoS4 in aquathermolysis was significantly different from its decomposition process under hydrogen and vacuum atmospheres. The laboratory experimental results showed that the heavy oil viscosity reduction rate was above 85 % with the action of in- situ formed MoS2 nanoparticles after aquathermolysis. The sulfur content of heavy oil and asphaltene, asphaltenes and aromatics contents of heavy oil were decreased significantly, indicating that the cracking and ring opening reactions did take place. In the oilfield experiment, the precursor (NH4)2MoS4 was injected into the reservoir along with steam. After one-time injection, the catalytic effect could be sustained for at least four months. The maximum viscosity reduction rate was as high as 90 % during the first week, and still around 70 % in the 4th month. The molecular structural analysis of the produced heavy oil proved that the asphaltenes has been effectively cracked during the in-situ catalytic aquathermolysis. Both the laboratory and oilfield experimental results demonstrated that (NH4)2MoS4 precursor could form MoS2 nanoparticle and effectively catalyze the upgrading reactions of heavy oil. We hope that this study will provide a new catalyst development strategy for the catalytic aquathermolysis exploitation technology of heavy oil.

Robust Asphaltene Onset Pressure Prediction using Ensemble Learning

Most works on asphaltene onset pressure (AOP) prediction rely on only one model without making them robust against noise. This paper takes a robust approach to train three machine learning models, namely the Multi-Layer Perceptron (MLP), CatBoost, and Random Forest (RF), to predict AOP as a function of oil composition, SARA fractions, saturation pressure and temperature. Moreover, a Power-Law Ensemble Model (PLEM) is used to integrate the predictions obtained from the individual experts. Robustness was achieved by tuning the hyperparameters using 5-fold cross-validation with multiple sets of noisy data. Results revealed that the robust approach could produce models outperforming the standard ones on noisy data by more than 10%, while keeping a good performance on original data. The PLEM could increase the coefficient of determination by a minimum of 3.4% relative to the best individual data-driven model regardless of the tuning strategy. Additionally, the proposed approach could outperform thermodynamic and mathematical models. In the end, Sobol sensitivity analysis showed that the concentration of C1-C7+, asphaltenes, saturates, CO2, and the saturation pressure had a positive impact on the AOP, while the temperature and concentration of N2, H2S, resins, and aromatics had a negative influence. The value of the work is in taking benefit of three distinct models to predict the AOP and employing a robust hyperparameter tuning approach to make the model robust against measurement errors. The findings indicate that the robust hyperparameter tuning increases the stability of the models, and combining the outputs of the models improves the prediction accuracy.

Experimental and numerical study of soot formation in hydrocarbon sprays under high-pressure fuel pyrolysis conditions

This study combined high-speed optical diagnostics and numerical simulation to investigate soot formation in n-dodecane sprays under conditions characterized by fuel pyrolysis and low oxygen concentrations. Numerical models were employed to predict the evolution of polycyclic aromatic hydrocarbons (PAHs), while the experiments focused on soot formation. A 186-µm single-hole orifice nominal diameter injector was employed to inject well-controlled fuel sprays into a constant-volume chamber operating at 76 bar. We use a short injection duration of approximately 100 µs to maximize the residence time of the fuel, with variations in the ambient gas temperature within the range of 1,400 to 1,700 K, and the oxygen concentration was ranged from 0 to 5 %. Additionally, we conducted closed-homogeneous-reactor and two-stage Lagrangian simulations with various kinetic mechanisms to predict PAH formation and compared the results with experimental data. The experimental results revealed that variations in the ambient temperature and oxygen percentage significantly influenced the pyrolysis and oxidation processes. Soot onset occurred at 1,450 K for oxygen levels of 0, 1, and 3 %, whereas at 5 % oxygen, soot formed at temperatures below 1,400 K. Interestingly, higher oxygen concentrations increased the rates of soot formation at all temperatures tested. By contrast, elevated temperatures reduce the total soot mass owing to enhanced oxidation. The present study also evaluates the influence of fuel composition on soot formation and observes that a higher aromatics content in the fuel leads to a lower soot onset temperature and increased soot mass. Notably, similar trends for both ethanol and n-dodecane fuels are identified in this study. Furthermore, the numerical calculations revealed distinct trends in PAH formation. Although the different mechanisms reasonably captured the trends in benzene formation, they differed in their predictions of the formation rate of pyrene, resulting in potential differences in soot processes. This disparity highlights the need for a comprehensive review and potential modification of the current soot modeling approach.

Peatland organic matter quality varies with latitude as suggested by combination of FTIR and Ramped Pyrolysis Oxidation.

We employed two compelling and distinct methods, Fourier Transform Infrared Spectroscopy (FTIR) and Ramped Pyrolysis Oxidation (Ramped PyrOx), to examine the quality of organic matter (OM) stored in four peatlands located along a latitudinal gradient (Tropical (4˚N), Subtropical (27˚N), Boreal (48˚N), and Polar (68˚N)). FTIR was used to quantify the relative abundance of carbohydrates, a relatively labile compound class, and aromatics, which are more recalcitrant, in a sample set of four peat cores. These samples were then prepared using Ramped PyrOx, a second, independent method of determining OM quality that mimics the natural diagenetic maturation of OM that would take place over long timescales. Previous large-scale studies using FTIR to evaluate OM quality have observed that it generally increases with increasing latitude (more carbohydrates, less aromatics). Here, we demonstrate that the Ramped PyrOx approach both validates and complements the FTIR approach. The data stemming from each Ramped PyrOx preparation was input to a model that generates an estimated probability density function of the activation energy (E) required to break the C bonds in the sample. We separated these functions into three fractions ("low E," "medium E," and "high E") to create Ramped PyrOx variables that could be quantitatively compared to the compound class abundance data from FTIR. In assessing the agreement between the two methods, we found three significant relationships between Ramped PyrOx and FTIR variables. Low E fractions and carbohydrate content were positively correlated (R2 = 0.51) while low E fractions were negatively correlated with aromatic content (R2 = 0.58). Medium E fractions were found to be positively correlated with aromatics (R2 = 0.69).

Catalytic vapor phase upgrading of sawdust pyrolysis using metal oxide catalysts: The support effect

Biocrude derived from biomass is unstable and has limited applications and vapor-phase upgrading of biomass pyrolysis over a catalyst can enhance bio-oil quality and yield, yet catalyst deactivation due to coke formation remains a major challenge. This study explores the effects of different magnesium oxide (MgO) catalysts supported on ZSM-5, Al2O3, ZrO2, TiO2 on the pyrolysis product yield, composition, and the extent of coke formation. Studies were conducted in a fixed-bed reactor at 550 °C at two different catalyst to biomass loadings (C/B) of 1:6, and 1:1. Non catalytic pyrolysis of sawdust resulted in the biocrude, gas, and char yields of ∼32 wt%, ∼29 wt%, and ∼39 wt% respectively. At a low C/B ratio, pyrolysis product yields were approximately comparable to those under non-catalytic conditions. However, at a high C/B ratio, biocrude yield decreased significantly with increase in gas yield, while char yield showed only minor changes. Using ZSM-5 and Al2O3 supported catalysts, low C/B ratios significantly increased phenolic content in the biocrude (∼58%). In contrast, higher C/B ratios enhanced the hydrocarbons (∼10%) and aromatics (∼32%) content, reducing phenolics and thereby lowering the biocrude's overall oxygen content, enhancing its stability. TiO2 and ZrO2 supports produced higher proportions of lower carbon chain length compounds, though with reduced hydrocarbon content compared to ZSM-5. ZSM-5 supported catalysts yield a high proportion of aromatic compounds, attributed to the synergy between the acidic sites of ZSM-5 and the basic sites of MgO that favored conversion of phenolics to aromatics through dehydroxylation and demethoxylation. Overall, this study highlights the influence of different catalyst supports in catalytic vapor phase upgrading of sawdust derived biocrude to selectively optimize bio-oil composition, increasing fuel or chemical potential while addressing coke formation.

Effects of Nitrogen Concentration in Nutrient Solution on Growth, Yield and Phytochemical and Aromatic Compounds of Persicaria minor Cultivated Using Hydroponics System

Persicaria minor, locally known as kesum and belonging to the family Polygonaceae, is a widely used aromatic herb in Malaysia. Cultivating kesum hydroponically using a deep-water culture (DWC) system presents an alternative method for growers to enhance crop yields. This system delivers a liquid fertilizer solution directly to the plant roots, eliminating the need for a growth medium or water flow. Kesum contains phytochemical compounds such as quercetin-3-glucuronide and quercitrin, which have medicinal properties. The primary objective of this study was to assess the effects of nitrogen concentration on the growth, yield, phytochemical (quercetin-3-glucuronide and quercitrin) and aromatic (aldehyde and caryophyllene) content of kesum cultivated in a hydroponic system. Plants were grown under four nitrogen concentration regimes: 200 mg/L, 100 mg/L, 50 mg/L, and 0 mg/L. The experiment was conducted under a side-netted rain shelter and arranged in a Randomized Complete Block Design (RCBD) with four replications. The plants were harvested eight weeks after planting. The result indicted those supplemented with 100 mg/L of nitrogen exhibited the best growth performance and biomass yield, along with the highest levels of aromatic compounds (aldehyde C-10: 5.80% and aldehyde C-12: 12.23%). Plants treated with 50 mg/L of nitrogen produced the highest amounts of quercetin-3-glucuronide (98.261 µg/mL) and quercitrin (61.367 µg/mL) compared to other treatments. Additionally, plants receiving 200 mg/L of nitrogen had the highest caryophyllene content (12.53%). In conclusion, the deep-water culture system in hydroponics can effectively cultivate kesum, allowing for adjustments in nitrogen concentration to achieve optimal yields, phytochemical levels, or aromatic compound production based on specific objectives.

Fungal Extracellular Enzymes from Aspergillus spp. as Promising Candidates for Extra-Heavy Oil Degradation and Enhanced Oil Recovery.

Heavy crude oil (HCO) and extra-heavy crude oil (EHCO) with high viscosity and density pose enormous challenges to the exploitation of oil reserves. While bacteria are increasingly used in biocatalytic upgrading of HCO and EHCO, less attention has been paid to the potential of fungi. The aim of this study was to ascertain the role of fungal extracellular enzymes from Aspergillus spp. In the biodegradation of EHCO and their application potential for enhanced oil recovery. A. terreus HJ2 and A. nidulans HJ4 with the ability to biodegrade HCO were previously isolated from bitumen enrichment cultures. Both strains grew well on EHCO agar plates supplemented with a small amount of soluble starch (0.2%) and yeast extract (0.3%). Extracellular enzymes from each strain separately, as well as mixtures of the enzymes, exhibited EHCO degradation activity, leading to redistribution of hydrocarbons with substantial formation of biogases and organic acids in a 7-day period. Enzymatic degradation resulted in decreased contents of resins and asphaltenes, accompanied by increased contents of saturates and aromatics. Gas chromatography-mass spectrometry revealed distinct redistribution patterns of n-alkane in the biotreated oil. Enzymatic degradation additionally caused considerable reduction in oil viscosity (by 12.7%) and heavy metal concentrations (Ni, by 44.1%; Fe, by 54.0%; V, by 31.6%). The results provide empirical evidence for the application potential of fungal extracellular enzymes from Aspergillus spp. in EHCO recovery and biocatalytic upgrading of EHCO.

Catalytic conversion of plastic waste into diesel fuel through pyrolysis and hydroprocessing

This study evaluates the potential of hydro-processed plastic pyrolysis oil (HPO) as a sustainable alternative fuel derived from mixed plastic waste. The physicochemical properties of diesel, mixed plastic pyrolysis oil (MPPO), and HPO were thoroughly analyzed according to IS standards, enabling a direct comparison and alignment of HPO characteristics with EN590 diesel fuel standards. Gas chromatography-mass spectrometry (GC-MS) analysis identified key fuel components—n-alkanes, alkenes, benzene, and naphthalene with HPO showing 98 % compositional similarity to commercial diesel. The HPO blend with various percentage of pure diesel ratio is (30:70, 60:40 and 90:10). The hydroprocessing technique effectively reduced the alkene content of MPPO, enhancing the purity and quality of the resulting HPO. This refinement was crucial in ensuring that the oil met the necessary fuel standards. Engine performance evaluations further indicated that blending HPO with conventional diesel resulted in emissions with 95 % similarity to those of standard diesel fuel. This close match in emission profiles underscores the potential of HPO as a cleaner and more environmentally friendly fuel alternative. Additionally, the increased aromatic content in HPO, due to hydroprocessing, significantly improved combustion properties. This enhancement not only supports the feasibility of using HPO as a substitute for traditional diesel but also suggests that HPO may offer superior performance in specific applications. Overall, these findings highlight the potential of HPO as a sustainable fuel option, capable of addressing the environmental impacts associated with both plastic waste and fossil fuel consumption. The study demonstrates the environmental benefits of converting plastic waste into valuable fuel through pyrolysis and hydroprocessing, offering a promising strategy for sustainable plastic waste management and advancements in environmental sustainability and the fuel industry.

Segregated Supply of Sustainable Aviation Fuel to reduce Contrail Energy Forcing – Demonstration and Potentials

Aviation contributes about 4 % to net anthropogenic climate forcing, with contrails being the largest individual contributor to radiative forcing from aviation. One option to mitigate contrail-related climate impacts is using kerosene containing fewer or no aromatic components and thus showing a higher hydrogen content compared to conventional kerosene (i.e., fossil fuel-based). Such “low contrail” kerosene can be provided as a blend of conventional (crude oil-based) and synthetic kerosene or from hydroprocessing conventional kerosene.Low contrail kerosene reduces contrail lifetime and optical thickness and thus the magnitude of contrail climate forcing. However, market shares of such kerosene are presently very low. Simultaneously, a small fraction (< 10 %) of all flights globally accounts for the majority (> 80 %) of global warming contrail climate forcing. Hence, the targeted use of low contrail kerosene on those flights appears promising. But, such an approach would require additional operational efforts, such as a duplication of supply lines and storage tanks.This study evaluates the feasibility and operational efforts of a segregated supply of a 35 m-% SAF-blend (14.34 m-% hydrogen content) to 84 winter time demonstration flights to reduce contrail climate forcing. Between 17th January 2023 and 2nd February 2023, low contrail kerosene was supplied to commercial A320 type aircraft flights on the route between Stockholm and Copenhagen in northern Europe. The operational feasibility and related efforts to target flights with the highest contrail energy forcing as well as a large-scale application are described. The evolution of contrails is tracked using data from the Meteosat Second Generation (MSG) satellite. The contrail energy forcing is calculated for the corresponding flight trajectories assuming another, well-validated engine model (CFM56-5B4 for the simulations instead of LEAP1A-26 for the demonstration flights) using the Contrail Cirrus Prediction (CoCiP) model with meteorological input fields from European Reanalysis data (ERA5).For the first time, the experiment demonstrates the operational feasibility for a segregated supply of low contrail kerosene to medium range aircraft at Stockholm airport. The segregated supply of low contrail kerosene can be realized for short to medium range flights, which can be fueled by a refueller truck. Targeting individual flights via single line hydrant fueling systems seems impractical as of now. Operational efforts to target single flights with highest contrail energy forcing are almost identical to the efforts in this demonstration experiment.Simulations estimate that the segregated supply of the medium blend kerosene (14.34 m-% hydrogen content) can reduce contrail energy forcing by about 11 % assuming the use of a “Rich-Quench-Lean” (RQL) engine (CFM56-5B4). The contrail climate benefit increases to >20 % for a 50 % blend ratio (14.7 m-% hydrogen content). Also, the location and evolution of the demonstration flights’ 28 contrails calculated with CoCiP was tracked with satellite data.The uncertainty of absolute contrail climate forcing estimates is mainly limited due to meteorological data input and also by lacking information on fuel composition in terms of cycloalkane, mono- and polycyclic aromatics content. Contrarily, the uncertainty of relative changes in contrail climate forcing is subject to low uncertainty, since it compares the use of different fuels for an identical fleet and identical weather conditions.