Low Sulfur Content Research Articles

Marine Fuel Regulations and Engine Emissions: Impacts on Physicochemical Properties, Cloud Activity and Emission Factors

AbstractMarine regulations aim to reduce sulfur and nitrogen exhaust emissions from maritime shipping. Here, two compliance pathways for reducing sulfur dioxide emissions, fuel sulfur content reduction and exhaust wet scrubbing, are studied for their effects on physicochemical properties and cloud forming abilities of engine exhaust particles. A test‐bed diesel engine was utilized to study fresh exhaust emissions from combustion of non‐compliant, high sulfur content fuel with (WS) and without (HiS) the usage of a wet scrubber as well as a regulatory compliant, low sulfur content fuel (LoS). Particle number emissions are decreased by ≈99% when switching to LoS due to absence of 20–30 nm sulfate rich particles. While number emissions for WS are also decreased, a shift in the sulfate mode toward larger sizes was found to increase particle mass emission factors by at least 31%. Changes in the mixing state induced by the compliance measures are reflected in the hygroscopicity of the exhaust particles. Fuel sulfur reduction decreased cloud condensation nuclei emissions by at least 97% due to emissions of primarily hydrophobic soot particles. Wet scrubbing increased those emissions, mainly driven by changes in particle size distributions. Our results indicate that both compliance alternatives have no obvious impact on the ice forming abilities of 200 nm exhaust particles. These detailed results are relevant for atmospheric processes and might be useful input parameters for cloud‐resolving models to investigate ship aerosol‐cloud interactions and to quantify the impact of shipping on radiative budgets from local to global scales.

Thermocapillarity transition-induced unconventional thermal behavior and dilution in laser welding of metals with dissimilar sulfur content

An enhanced three-dimensional transient Thermal-Fluid-Dilution model, integrating a sub-model that accounts for surface tension, is proposed to investigate the unconventional thermal behavior and dilution induced by the surface-active element (sulfur) during the laser joining process of 304SS with higher sulfur content and pure nickel with lower sulfur content. Surface tension is modeled as a function dependent on local temperature and the concentration of the surface-active element (sulfur) at the free surface. The temperature and sulfur-dependent surface tension initially generate an unconventional driving force, subsequently leading to the transitions of heat transfer, flow pattern, and species dilution. Specifically, the inclusion of the sulfur effect results in a redistribution of larger surface shear stress along the transition boundary, causing unconventional flow behavior. The temperature coefficient of surface tension (TCST) is the coexistence of TCST (-) and TCST (+), leading to a novel flow pattern with combined inward-outward flows. Moreover, the anomalous flow exhibits observed phenomena such as the rotation of the major axis (RA) and center line shift (CLS) within the melt pool, showing more reasonable simulated melt pool dimensions when accounting for the sulfur effect. Additionally, the dilution model integrated with the unconventional flow pattern presents a more uniform concentration distribution compared to the conventional dilution. Finally, the simulated distribution of alloy elements is validated effectively by experimental data obtained from Energy Dispersive Spectrometer (EDS) analysis.

Sulfide compositions of young Chang’e-5 basalts and implications for sulfur isotopes in lunar basalt sources

Sulfides are accessory phases in lunar rocks butare important forunderstanding lunar interior processes as well as impacts on the lunar surface.Whether or not the lunar mantle had achieved sulfide saturation during magma ocean evolution and displays homogeneous sulfur isotopes remains under debate. TheChang’e-5 (CE-5) mission returned young (2.0 Ga) basalts from a mare terrain in thenorthern Oceanus Procellarum.Here we study chemical and sulfur isotopic compositions (δ34SV-CDT) of sulfides from CE-5 basaltic fragments and combine them with δ34S of other young (3.1–3.0 Ga) lunar low-Ti basalt (NWA 10597 and NWA 4734) and gabbro meteorites (NWA 6950) to compare them with Apollo low-Ti and high-Ti mare basalts. The sulfides in basaltic fragments of CE-5 are troilites (FeS) with lowabundances ofNi, Co, and Cu(e.g., Ni < 0.04 wt% and Ni/Co < 0.3). Textures and chemical compositions indicate that most troilites arelate-stage crystallization products fromthe highly evolvedCE-5 basalts. Several troilites occur in the matrices of impactite clasts and are intergrown with Fe–Ni metal(12–36 wt% Ni, Ni/Co of 12–39). These troilites are distinct from the major population of troilites withnoticeably higher Ni abundances (mostly > 0.2 wt% with Ni/Co of 1–3) andreconcile with the addition of meteoritic materials into the impact melts.The δ34SV-CDTof large troilite grains (>10 μm) from the CE-5 basaltic fragments and lunar meteorites were obtained by high-precision, high-spatial-resolution femtosecond laser ablation MC-ICP-MS which achieved external uncertainty (0.65 ‰, 2SD at 8-μm laser spots) like nano-SIMS. Sulfur degassing during surficial effusive lava flow likely led to a slightdecrease inδ34S (by ∼ 1 ‰) for some basaltic fragments; however, such effects were limited to the scale of bulk rock samples, consistent with previous results. The mean δ34Sof troilites in CE-5 basaltic fragments (0.35 ± 0.25 ‰, 2SE, n = 45) is similar to those of ancient (3.8–3.1 Ga old) Apollo low-Ti and high-Ti mare basalts and the young gabbro cumulate NWA 6950 (0.56 ± 0.21 ‰, 2SE, n = 10). The paired NWA 10597 and NWA 4734 show consistent δ34S, lower than most values by ∼ 0.5 ‰. Current data thus indicate that most mantle sources of lunar basalts would be homogeneous for δ34S(0.6 ± 0.3 ‰) and minor regions may be different. The overall homogenous δ34S from different mantle sources with variably low sulfur contents supports sulfide-undersaturated accumulation of the lunar magma ocean, which was inherited from strong volatile loss and evaporative fractionation during the formation of the Moon.

Nanohybrid of two-dimensional tellurium and metal sulfotelluride for solar-driven photocatalytic hydrogen production from seawater

The use of sunlight radiation to cause the dissociation of seawater has tremendous promise as a green method for hydrogen production. Herein, tellurides and sulfotellurides of cadmium and zinc and solid solutions like CdxZn(1−x)SyTe(1−y) were synthesized by a coprecipitation method at room temperature. The prepared materials were tested as photocatalysts to produce H2 from seawater using lactic acid as a sacrificial reagent assisted by a solar simulator. All photocatalysts were active for hydrogen production from seawater and artificial sunlight. The cadmium-free photocatalyst (ZnSTe) was the most active one with a hydrogen production rate of 378.85 µmol g−1 h−1, followed by CdZnSTe (374.7 µmol g−1 h−1). The low sulfur content profoundly changes the UV–vis absorption spectra of the sulfotellurides, improving photocatalytic activity. XPS and TEM analysis revealed that the ZnSTe is composed of elemental tellurium nanosheets decorated with nano amorphous ZnTe and cubic phase ZnO. Thus, the p-n heterojunction formation between the ZnTe and ZnO improves the separation and migration rates of photogenerated carrier pairs, improving the solar-driven H2 production. Furthermore, the presence of 2D Te nanosheets dispersed in ZnSTe may contribute as support for charge transfer, which is essential in increasing photocatalytic activity.

Co-Valorisation Energy Potential of Wastewater Treatment Sludge and Agroforestry Waste

The growing demand for sustainable and environment-friendly energy sources resulted in extensive research in the field of renewable energy. Biomass, derived from organic materials such as agricultural waste, forestry products, and wastewater treatment plant (WWTP) sludge, holds great potential as a renewable energy resource that can reduce greenhouse gas emissions and offer sustainable solutions for energy production. This study focused on diverse biomass materials, including sludge from WWTPs, forest biomass, swine waste, cork powder, and biochar. Chemical and physicochemical characterizations were performed to understand their energy potential, highlighting their elemental composition, proximate analysis, and calorific values. Results showed that different biomasses have varying energy content, with biochar and cork powder emerging as high-energy materials with net heating values of 32.56 MJ/kg and 25.73 MJ/kg, respectively. WWTP sludge also demonstrated considerable potential with net heating values of around 14.87 MJ/kg to 17.44 MJ/kg. The relationships between biomass compositions and their heating values were explored, indicating the significance of low nitrogen and sulphur content and favourable carbon, hydrogen, and moisture balances for energy production. Additionally, this study looked into the possibility of mixing different biomasses to optimize their use and overcome limitations like high ash and moisture contents. Mixtures, such as “75% Santo Emilião WWTP Sludge + 25% Biochar,” showed impressive net heating values of approximately 21.032 MJ/kg and demonstrated reduced emissions during combustion. The study’s findings contribute to renewable energy research, offering insights into efficient and sustainable energy production processes and emphasizing the environmental benefits of biomass energy sources with low nitrogen and sulphur content.

Sulfurized polyacrylonitrile as cathodes for advanced lithium-sulfur batteries: advances in modification strategies.

Sulfurized polyacrylonitrile (S@PAN) composites have gathered a lot of interest because of their advantages of high theoretical energy density, excellent cycling stability, and environmental friendliness. Meanwhile, their unique "covalent bonding" mechanism effectively avoids the dissolution and shuttling of polysulfides, and thus they are expected to be the most promising candidate for the cathode material in lithium-sulfur (Li-S) batteries. Over the past five years, S@PAN cathode materials have been widely studied in Li-S batteries, and it is very important to summarize the advances over time for their practical applications. This article reviews the latest progress concerning the modification of S@PAN cathode materials for improving poor electrical conductivity, low sulfur content, and sluggish reaction kinetics, and proposes possible research directions. We hope this review provides valuable insights and references for future research on Li-S batteries.

The risk of explosion during the transport and storage of liquid fuels

When transporting and storing liquid fuels, explosive atmospheres can form which, under certain conditions, can be initiated with different sources, of which static electricity has proven to be the source of ignition in many cases of fires and explosions that have occurred. As a result of the environmental regulatory requirements to reduce the noxes emitted by diesel engines, the oil industry introduced into production fuels with ultra-low sulfur content (ULSD Ultra Low Sulfur Diesel), clean burning diesel, and low sulfur content (LSD Low Sulfur Diesel). The new types of fuels present a greater risk of explosion than fuels with a high sulfur content because they have other explosive characteristics and are electrostatically charged much more easily. The paper presents some aspects regarding the risk of explosions during the transport and storage of liquid fuels with the highlighting of additional risks in the case of ULSD Also, the paper highlights the factors that must be taken into account when establishing the technical and organizational measures that must be taken to prevent ignition and that must be implemented in the work procedures of manufacturers, suppliers, transporters and users of ULSD.

SO2 emissions from the Timanfaya eruption (1730–36 CE), Lanzarote, Canary Islands

The 1730–36 CE eruption of Lanzarote (Canary Islands) is the third largest basaltic fissure eruption known to have occurred in the last 1000 years, after the Icelandic events of Laki (1783–84 CE) and Eldgja (939 CE). Approximately 5.2 km3 (1.1 × 1012 kg) of alkalic basalt (sensu lato) lava and pyroclastic rocks were emplaced on land, with a further unknown amount entering the sea, The activity occurred in five eruptive phases from vents situated along a 15-km long, E-W trending fissure. Each phase began with Strombolian fire fountain activity, building large spatter and scoria cones, accompanied and followed by effusive ‘a'ā and pāhoehoe lava flow emplacement. Phases I and II were the most explosive and occurred between 1st September 1730 and June 1731. Samples of scoria and lava surfaces were collected from all phases and the major elements, S, Cl and F contents of matrix glasses and glass inclusions in olivine (the dominant phenocryst phase) were analysed by electron microprobe. Water contents of selected glasses were measured on polished wafers by Fourier Transform Infrared spectroscopy. Glass compositions mimic the range of published whole rock compositions, with Phase I being predominantly basanitic and later phases alkali basalt. Whole rock variations in incompatible trace element ratios are mimicked by ratios involving TiO2, K2O and P2O5 in glass. Matrix and glass inclusion analyses in a given sample are similar, indicating that the inclusions formed synchronously with eruption and that most phenocryst crystallization occurred during earlier evolution of the magmas. Matrix glasses in scoria and surface lava samples have 80–300 ppm S and 260–750 ppm H2O, whereas glass inclusions in olivine have 420–2650 ppm S and 0.1 to 0.5 wt% H2O. Glass inclusions with low sulfur contents were trapped during degassing-induced crystallization as the magma approached the surface. The inclusions with the highest sulfur contents, at given P2O5/TiO2 ratio, are inferred to represent un-degassed melt, and their S content and S/K2O ratios correlate very strongly with incompatible element concentrations and P2O5/TiO2 ratios. The original S contents of 131 matrix glasses were calculated from their P2O5/TiO2 ratios and compared to their measured degassed S contents. The mass of S released per unit mass of magma ranged from about 0.25% in Phase I Episode 1to 0.17% in later phases, with propagated uncertainties of about 2 to 5%. About 40 Mt. of SO2 was released overall, with ca. 25 Mt. being released during the first 5 months of the eruption (Phase I). Estimates of average magma discharge rates imply that plumes remained in the troposphere, with the possible exception of those associated with extreme peak discharge rates during Phase I Episode 1 which may have just reached the upper troposphere – lower stratosphere. Lower eruption rates during the later phases would have confined SO2 emissions to the troposphere. Although acid and sulfate peaks dated to 1730 and 1731 have been reported from some Greenland ice cores, the evidence for stratospheric impact, such as cooling at the Earth's surface and increased stratospheric turbidity, is minimal.

Biomass Waste Conversion Technologies for its Utilization and Energy Generation in India: A Perspective

The speedy reduction of fossil fuels and its analogous environmental issues make it necessary for attention to energy generation from alternative fuels. Biomass seems to be one of the likely sources of renewable energy and the computation of waste materials into an appropriate kind of energy, like fuel or electricity, can be completed in several multifarious feasible ways. Utilizing biomass for energy production offers several advantages, including cost-effectiveness, lower sulfur content, and reduced greenhouse gas emissions, contributing to improved environmental sustainability in energy generation processes. This paper takes stock of exploring various biomass conversion technologies for its utilization that can facilitate power generation from biomass waste. It is important to note that biomass utilization extends beyond traditional combustion methods. Latest conversion technologies, including thermal, chemical, and biological processes, have proven to be efficient methods that can replace fossil fuels for producing energy from high-grade sources.

Fractographic research of destruction of 34CrNi1Mo steel gear shaft

Goal. The purpose of this research work is to establish the causes and mechanisms of destruction of gear shaft made of 34CrNi1Mo steel, to provide recommendations to prevent this type of product damage. Methodology. The gear shaft made of 34CrNi1Mo steel destroyed during operation was studied. The fracture surface of the investigated steel was studied by macroanalysis and scanning electron microscopy using a SEM-100У microscope at a magnification of 1500-10000 times. Microstructural analysis of 34CrNi1Mo steel was carried out on Neophot-21 optical microscope at x250, 300; 800 magnification. Microhardness was measured according to the standard method on a PMT-3M microhardness tester at a 50 g loading. Results. The causes and nature of the operational destruction of the gear shaft made of steel grade 34CrNi1Mo were analyzed. The fatigue nature of fracture was determined. The unsatisfactory quality of the surface of the experimental product was established: shells, pores, scratches, chips were found on the surface. The destruction began in the place of the geometric stress concentrator (surface defect – shell) due to metal chipping. Originality. The features of the destruction of the gear shaft were determined: at the break, there is a significant distance between the fatigue grooves, which indicates a high crack propagation rate, the fatigue grooves are weakly expressed, irregular, which indicates the limited possibilities of steel to plastic deformation. The fractographic surface of the fracture is shiny and consists of cleavage facets, covered with coarse scars, fan-shaped diverge from the focus, has a coarse-grained structure, typical for brittle fracture. The brittle nature of the fracture was confirmed by scanning electron microscopy. The surface microrelief contains cleavage facets, microcracks, and intergranular spall cells. Non-metallic inclusions of MnS, which are additional structural stress concentrators, have been revealed. Microcracks originate near non-metallic inclusions; at the boundaries of former austenite grains, especially at their triple junctions; at the interface between matrix and secondary phases. An increase in microhardness from 2500 to 4750HV after heating to 840–860°C with subsequent cooling in air was established, which can be explained with the probable hardening of the experimental steel, which, along with an increase in hardness, leads to a decrease in steel ductility. Practical value. It is recommended to use steel with a low sulfur content, additional gear shaft surface treatment to prevent the formation of stress concentrators in places of surface discontinuities; compliance with the nominal temperature regime also prevents spontaneous hardening of the product material.

Synthesis and characterization of new nanocomposite Cu6W18O70⊂CuFe2O4 as an efficient nanocatalyst for oxidative desulfurization of real and model gasoline

AbstractThe primary objective of this investigation was to develop a new nanocatalyst that could produce materials with a lower sulfur content, thereby reducing its environmental harm. To achieve this, the researchers used the sol‐gel method to synthesize a heterogeneous nanocatalyst by attaching sandwich‐type polyoxotungstate [(CuW9O34)2Cu4(H2O)2−10] (denoted as Cu6W18O70) clusters on the surface of copper ferrite nanoparticles (CuFe2O4 NPs). To characterize the nanocatalyst, several analysis techniques were employed, including Fourier transform infrared spectroscopy, ultraviolet‐visible, powder X‐ray diffraction, and scanning electron microscope. The oxidative desulfurization of hazardous sulfur‐containing real and model fuel oils was effectively catalyzed by the Cu6W18O70⊂CuFe2O4 nanocatalyst. According to the experimental findings, the best efficiencies in oxidation reaction were achieved in 1 h contracting time at 35°C, which was as high as 95%. The Cu6W18O70⊂CuFe2O4 nanocatalyst exhibited impressive removal rates (%) on dibenzothiophene (C12H8S), benzothiophene (C8H6S), and thiophene (C4H4S) of model fuels, with figures reaching 97%, 96% and, 96% respectively. Furthermore, multiple recycling of the uniform nanocatalyst can be achieved effortlessly through filtration, without experiencing any notable decline in activity. Therefore, the authors suggest that this study will pave the way for the widely used mentioned nanocatalyst in the practical and workable organization of petroleum fractions.

INCREASING THE EXTRACTION OF VACUUM GAS OIL AT THE ELOU-AVT UNIT

The ELOU-AVT unit is part of a large oil refining complex. This unit is designed for primary processing of oils from various fields, as well as their mixtures. Refining is carried out in order to separate oil into separate fractions (gasoline, kerosene, diesel fuel, fuel oil), which are used as raw materials for secondary oil refining at other units. On the territory of modern refineries, in order to increase the depth of processing of petroleum feedstock, in most cases the following technological units are used: – The isomerization unit is designed for the production of low-boiling high-octane isomerizate used as a component of unleaded motor gasolines. For the production of a low-boiling high-octane component, the plant uses the process of low-temperature isomerization of C5-C6 normal paraffins. – The distillate hydrotreating unit is designed to produce high-quality diesel fuel with low sulfur and nitrogen content, high cetane number, and improved low-temperature properties. – The sulfur production unit is designed to produce solid commercial sulfur by the oxidative conversion of hydrogen sulfide into elemental sulfur. The delayed coking unit is designed to process heavy oil residues (straight-run tar) into lighter gaseous, liquid products and petroleum coke. The process of thermal cracking is the basis for the processing of tar. – The catalytic reformer with preliminary hydrotreatment is designed for the processing of gasoline fractions of oil in order to obtain high-quality gasolines and aromatic hydrocarbons, as well as hydrogen-containing gas (HCG), which is widely used both in petrochemistry and in such oil refining processes as: hydrotreating, hydrocracking, isomerization, etc. Oil refining is a multi-stage process of physical and chemical processing of crude oil, which results in the production of a complex of petroleum products. Industrial primary distillation units are divided into atmospheric (AT), vacuum (VT) and combined (for example, AVT, CDU-AVT, etc.). It is impossible to obtain a single marketable oil product from crude oil directly by one process (with the exception of gases), all of them are obtained by sequential processing at several installations. Keywords: ELOU-AVT machine, distillate hydrotreating unit, Oil refining, multi-stage process, primary distillation units

A Method for Determining the Sulfur Isotope Composition in Ultramafic–Mafic Rocks with a Low Sulfur Content

A Method for Determining the Sulfur Isotope Composition in Ultramafic–Mafic Rocks with a Low Sulfur Content

Enhancing Soybean Yield: The Synergy of Sulfur and Rhizobia Inoculation.

Sulfur deficiency severely limits soybean growth, inhibiting the rhizobia nitrogenase and soybean protein synthesis. This study assessed the impact of sulfur fertilization and rhizobia inoculation on soybean growth and nitrogen fixation through bacterial culture and hydroponic experiments. We selected three rhizobia strains for bacterial cultures and used six sulfur levels. The test demonstrated severe inhibition of Rhizobium USDA110 growth without sulfur. In hydroponic experiment, we employed five sulfur levels with USDA110 as the inoculum strain. Soybean growth, nitrogen fixation, yield, and root morphology-related parameters, and root nodule growth, were significantly inhibited without sulfur. Following Rhizobium inoculation, low sulfur concentrations (0.15-0.60 mM) stimulated early-stage (V9) root growth and increased shoot nitrogen accumulation, but inhibited root growth at R5 stage. Furthermore, Rhizobium inoculation notably enhanced soybean growth, nitrogen fixation, and yield, especially within the recommended low sulfur concentration range (0.15-0.30 mM). The maximum nodule nitrogenase activity at R5 stage and highest yield was recorded at a 0.3 mM sulfur concentration with Rhizobium inoculation, which was 9.51-1222.07% higher than other treatments. These findings highlight that low sulfur concentration and rhizobia inoculation enhance soybean growth, nitrogen fixation, and yield but reduce soybean root efficacy, increasing reliance on root nodules.

Evidencing contributions arising from disorder-rich rhombohedral stacking-order regions in S-doped carbon nanotube buckypapers

The recent observations of superconductive-ordering in carbon-based systems consisting of rhombohedral stacking-faults, trilayer graphene (ABC-stacks) or dislocation-rich interfaces (pyrolytic graphite) have attracted a significant attention. Here we report an unusual nucleation of rhombohedral (ABC) stacking-faults in low-dimensional systems comprising of multiwall carbon nanotube (CNT) buckypapers, in experiments involving doping with sulfur. Interestingly, at low sulfur-concentrations, a broad-band at the Raman shift from 1800 to 2000 cm−1 was frequently identified, evidencing contributions arising from disorder-rich regions with rhombohedral stacking-order (ABC-stacks), as confirmed by X-ray diffraction and Rietveld refinements. These observations were further supported by a broadening in the left-shoulder of the 2D band at higher frequencies. T-ESR in the T range from 300 K to 77 K revealed multiple resonant signal splitting, indicative of paramagnetic contributions arising from the conduction π-electrons of the CNT and from amorphous iron-based-sulfides. Presence of CS bonding was revealed by Raman- and X-ray photoelectron-spectroscopy, evidencing a modification of the CNT. A sulfur-induced collapse within the CNTs-structure was found at high concentrations, as a consequence of a substitutional doping process and investigated through XRD, Rietveld refinements, TEM, HRTEM and magnetometry. ZFC/FC and magnetization vs field acquisitions revealed an interplay of ferromagnetic, paramagnetic and diamagnetic components with the diamagnetic-susceptibility χ being −2.85 ∗ 10−6 (emu/gOe) at T ~ 30 K.

Diesel Hydrodesulfurization and its Impact on the Fuel Market in Ecuador: A Review

This article examines the hydrodesulfurization process used to produce diesel with low sulfur content in Ecuador. The analysis covers the level of processing in the country, the quality of domestic diesel compared to other nations, and the technical and economic requirements of the process. It also explores the need to modify or upgrade catalysts to achieve deep hydrodesulfurization.. Unfortunately, the review found that sulfur content in Ecuadorian deposits is very high, with 3.53 MMkg produced in 2018. Despite improvements in the country’s refineries, diesel sulfur content has only been reduced to 110 ppm.. Ecuador regulates sulfur emissions through the Ecuadorian standard NTE INEN-1489 (2012). This norm classifies the fuel into three types, diesel #1 (3000 ppm), diesel #2 (7000 ppm), and premium diesel (500 ppm), following the use of diesel both in the industrial and transportation sectors. However, Ecuador seeks to adjust to countries with stricter regulations, such as the European Union. The standard that regulates sulfur emissions in this community is Euro VI, which limits the concentration to 10 ppm. One of the challenges in achieving international standards in the hydrodesulfurization units of the Ecuadorian refineries is to modify or improve the catalytic systems. Trimetallic catalysts, both supported and unsupported, can help overcome this challenge by decomposing the refractory molecules (e.g., dibenzothiophene and 4,6-dimethyldibenzothiophene) found in deep hydrodesulfurization. These catalysts can handle molecules that commonly used catalysts such as CoMo or MoW cannot. Therefore, proposals such as using trimetallic catalysts to achieve deep hydrodesulfurization levels are techno-economic options for Ecuador.&#x0D; Keywords: diesel, sulfur, Ecuador, hydrodesulfurization, refineries, catalyst.

Comprehensive Characterization of Some Selected Biomass for Bioenergy Production.

There is a lack of information about the detailed characterization of biomass of Nigerian origin. This study presents a comprehensive characterization of six biomass, groundnut shells, corncob, cashew leaves, Ixora coccinea (flame of the woods), sawdust, and lemongrass, to aid appropriate selection for bio-oil production. The proximate, ultimate, calorific value and compositional analyses were carried out following the American Standard for Testing and Materials (ASTM) standards. Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and X-ray fluorescence were employed in this study for functional group analyses, thermal stability, and structural analyses. The H/C and O/C atomic ratios, fuel ratio, ignitability index, and combustibility index of the biomass samples were evaluated. Groundnut shells, cashew leaves, and lemongrass were identified as promising feedstocks for bio-oil production based on their calorific values (>20 MJ/kg). Sawdust exhibited favorable characteristics for bio-oil production as indicated by its higher volatile matter (79.28%), low ash content (1.53%), low moisture content (6.18%), and high fixed carbon content (13.01%). Also, all samples showed favorable ignition and flammability properties. The low nitrogen (<0.12%) and sulfur (<0.04%) contents in the samples make them environmentally benign fuels as a lower percentage of NOx and SOx will be released during the production of the bio-oil. These results are contributions to the advancement of a sustainable and efficient carbon-neutral energy mix, promoting biomass resource utilization for the generation of energy.

Development of method for managing risk factors for emergency situations when using low-sulfur content fuel in marine diesel engines

The operation process of marine diesel engines when using fuel with a sulfur content of no more than 0.1 % was chosen as the object of the study. Similar types of fuel are characterized by a lower auto-ignition temperature and higher calorific value. During combustion, this leads to an increase in the rate of fuel combustion and the degree of pressure increase during combustion, precisely because of this, the dynamic loads on the parts of the cylinder-piston group and diesel engine bearings increase. Also, this (due to the increase in temperature at the end of combustion) creates conditions for an increase in the concentration of nitrogen oxides in diesel exhaust gases. This (namely, the change in dynamic and thermal loads that occur during the use of fuels with a reduced sulfur content in marine diesel engines) leads to the occurrence of emergency situations. As a method of managing the risk of such emergency situations, the reconfiguration of the high-pressure fuel equipment, namely the change of the advance angles of the fuel supply, is proposed. The research was carried out on a vessel intended for the transportation of containers and on which a marine diesel engine 8K80ME-8.2-TII MAN-Diesel &amp; Turbo was installed as the main engine. Combustion pressure, the degree of pressure increase during combustion, the temperature of exhaust gases, and the concentration of nitrogen oxides in exhaust gases were chosen as the indicators for evaluating the use and implementation of the proposed method. It has been experimentally proven that this results in an increase in the environmental sustainability of diesel operation by 3.61–10.97 %, an increase in thermal stability – up to 2.54 %, and an increase in dynamic stability – up to 4.82 %. This is due to the shift of the self-ignition and combustion process towards expansion and the corresponding decrease in pressure and temperature at the end of combustion. The most favorable use of this method is on modern diesel engines that have an electronic fuel injection control system, so they do not require mechanical reconfiguration of fuel pumps. Taking this into account, the method based on the change of fuel advance angles is defined as the one that provides management of the risk factors of emergency situations when using low-sulfur fuel in marine diesel engines.

Method for Determining the Sulfur Isotopic Composition in Ultramafic-Mafic Rocks with a Low Sulfur Content

The method of sample decompounding and silver sulfide precipitation for determination of the isotopic composition of sulfur by isotope mass spectrometry has been tried out and improved. The analytics and methodology of preparing test samples for analysis are described, task variations are indicated. The validity of the developed method of sample preparation was verified by a comparative analysis of various methods in three laboratories using internationally certified standards.

Source of inorganic components in the Middle Jurassic inertinite-rich coals of the Southern Ordos Basin, China: With emphasis on formation of Sr- and Ba-bearing minerals

The Middle Jurassic coal seams located in the southern Ordos Basin display notably high concentrations of barium (Ba) and strontium (Sr). To acquire a comprehensive understanding of the source and occurrence of the elevated contents of Ba- and Sr-bearing minerals and their formation mechanism in the coal, a suite of petrological, mineralogical, and geochemical analyses was conducted on the Middle Jurassic coals of the Gaojiapu mine (No. 4 Coal) from the Binchang mining area, using optical microscopy, field emission-scanning electron microscopy, X-ray diffraction, X-ray fluorescence, and inductively coupled plasma mass spectrometry. The results indicate that the No. 4 Coal is a high volatile B bituminous coal, which is characterized by low ash, medium sulfur, and high inertinite contents. The modes of occurrence of minerals identified in the coal, including calcite, dolomite, pyrite, quartz, kaolinite, anatase, barite, and celestine, indicate that the No. 4 Coal may have been subjected to multiple stages of solutions injection. Barium and Sr in the investigated coals are significantly enriched, exhibiting maximum values of 19738 μg/g and 9932 μg/g, respectively, while concentrations of other trace elements are generally depleted. Barite and celestine, generally coexisting with carbonate minerals, commonly occur as cell- and fracture-fillings. Furthermore, the strong correlation coefficients (r) for Ba vs. Ca + Mg and Sr vs. Ca + Mg (0.78 and 0.61, respectively) indicate that most barite and celestine have a close association with carbonate minerals of epigenetic origin. The highly elevated concentrations of Ba and Sr are thought to be primarily derived from solutions leaching barite deposits developed in the Qinling Orogenic Belt, which is located in the south of the Ordos Basin. When mapped spatially, the distributions of Ba and Sr concentrations are fan-shaped, decreasing from the NW to the SE of the mining area. Meteoric water containing dissolved CO2 induced partial dissolution of carbonate rocks, and during this process, selected metal ions (e.g., Ca2+, Mg2+, Al3+, Si2+, Fe2+, Ba2+, and Sr2+) were redistributed and subsequently migrated along fracture zones to the coal seam. The fracture systems and abundant cavities within inertinite in the coal provided sufficient space and conduits for solutions migration.