High Oxygen Content Research Articles

Non-graphitic carbon as sodium-ion battery anode materials with improved ratio of plateau to sloping capacities prepared from lignite-based organic maceral

Herein, huminite concentrate is obtained from lignite with high yield of 68.9 % by density gradient separation, subsequently converted to non-graphitic carbon (HM-H) by carbonization at 1400 °C for 2 h. Huminite concentrate possesses relatively high oxygen content and considerable amount of aromatic component, with modest yield of volatile matter during pyrolysis, resulting in optimized carbon phase distribution and enhanced electrical conductivity of HM-H. Compared with HM prepared by direct carbonization of lignite, HM-H has slightly higher contents of pseudo-graphitic and graphite-like carbons, and lower content of highly disordered one. Notably, HM-H exhibits remarkably improved electrical conductivity (1773 S m−1) than HM (1406 S m−1). Compared with HM anode for SIBs, HM-H one delivers higher plateau capacity (170.1 mAh g−1) meanwhile lower sloping capacity (91.8 mAh g−1), with significantly improved rate and cycling performances. Full cell assorted with NaFe1/3Ni1/3Mn1/3O2 cathode and HM-H anode demonstrates higher energy density of 210.5 Wh kg−1 than its counterpart (193.8 Wh kg−1) at 20 mA g−1, with superior rate performance (208.6 mAh g−1 at 200 mA g−1) and a capacity retention ratio of 89.7 % after 100 cycles. This work provides a facile and effective strategy for preparing non-graphitic carbon as high-performance anode materials for SIBs.

EFEK BLENDING BAHAN BAKAR TERBARUKAN BUTANOL 5% PADA PERTAMAX TERHADAP PERFORMA MESIN BENSIN EFI 150 CC

Butanol is an alternative energy that is being developed to overcome the energy crisis. This is because butanol has a high Octane number and oxygen content so it can optimize engine performance. This research was carried out to determine the impact of adding butanol to Pertamax on gasoline engine performance. The engine used is a 150 cc EFI petrol engine. The fuel uses Pertamax with butanol additive. Testing uses speed variations of 1000 – 3000 rpm. Test results: The performance of the 150 cc EFI petrol engine using the Pertamax-butanol mixture (P95B5) has increased compared to using pure Pertamax fuel (P100). This can be seen from the increase in torque and power with Pertamax-butanol fuel (P95B5) of 3.57 N.m and 1.12 kW, the highest increase at rpm 3000. Engine fuel consumption decreased when butanol was added compared to pure Pertamax (P100). The lowest fuel consumption occurred with Pertamax-butanol (P95B5) fuel at 0.21 ml/s when the engine speed was 100 rpm. Meanwhile, the highest fuel consumption occurred in Pertamax fuel (P100) at 0.62 ml/s when the engine speed was 3000 rpm

Catalytic upgrading of the heavy fraction of waste coffee grounds pyrolysis bio-oil using supercritical ethanol as a hydrogen source to produce marine biofuel

Biomass pyrolysis oil has the potential to serve as a sustainable fuel in the maritime sector, either through the production of marine biofuel or as fuel blends. However, the production of biofuels with high energy value and low oxygen content during the upgrading process calls for a more in-depth understanding. Herein, the heavy fraction of bio-oil was upgraded in supercritical ethanol in order to produce a biofuel which can be used as an alternative for heavy fuel oil (HFO). The impact of distinct operational factors such as temperature, holding time, and amount of catalyst was experimentally evaluated on the upgrading process. Using an MgNiMo/SAPO-11 catalyst, the supercritical ethanol upgrading of CG-BO heavy fraction at 325 °C and 4 h reaction time yielded a biofuel product with a 63.2 % yield, 0.07O/C ratio and high heating values over 39 MJ/kg. The prevailing fractions observed in the upgraded bio-oil primarily encompassed esters and hydrocarbons.

Mass spectrometric analysis of unprecedented high levels of carbonaceous aerosol particles long-range transported from wildfires in the Siberian Arctic

Abstract. Wildfires in Siberia generate large amounts of aerosols, which may be transported over long distances and pose a threat to the sensitive ecosystem of the Arctic. Particulate matter (PM) of aged wildfire plumes originating from Yakutia in August 2021 was collected in Nadym and on Bely Island (both in northwestern Siberia). An advanced analysis of the chemical composition of aerosol particles was conducted through a multi-wavelength thermal–optical carbon analyzer (TOCA) coupled to resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (REMPI-TOFMS) as well as through ultra-high-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). In Nadym, concentrations of organic carbon (OC) and elemental carbon (EC) peaked at 100 and 40 µg m−3, respectively, associated with Angström absorption exponents for 405 and 808 nm (AAE405/808) between 1.5 and 3.3. The weekly average on Bely Island peaked at 8.9 µg m−3 of OC and 0.3 µg m−3 of EC and AAE405/808 close to unity. In particular, ambient aerosol in Nadym had a distinct biomass burning profile with pyrolysis products from carbohydrates, such as cellulose and hemicellulose, as well as lignin and resinoic acids. However, temporarily higher concentrations of five- and six-ring polycyclic aromatic hydrocarbons (PAHs), different from the PAH signature of biomass burning, suggest a contribution of regional gas flaring. FT-ICR MS with electrospray ionization (ESI) revealed a complex mixture of highly functionalized compounds, containing up to 20 oxygen atoms, as well as nitrogen- and sulfur-containing moieties. Concentrations of biomass burning markers on Bely Island were substantially lower than in Nadym, flanked by the appearance of unique compounds with higher oxygen content, higher molecular weight, and lower aromaticity. Back-trajectory analysis and satellite-derived aerosol optical depth suggested long-range transport of aerosol from the center of a Yakutian wildfire plume to Nadym and from the plume periphery to Bely Island. Owing to lower aerosol concentrations in the plume periphery than in its center, it is demonstrated how dilution affects the chemical plume composition during atmospheric aging.

Thermo-oxidative resistance of C-rich SiCN(O) nonwovens influenced by the pretreatment of the silazane

C-rich SiCN(O) ceramic nonwovens with thermo-oxidation resistance up to 600 °C were developed from electrospinning of polyacrylonitrile in combination with different ratios of an oligomeric or polymeric silazane and subsequent pyrolysis. The influence of the selective pre-polymerization of the oligosilazane and the respective amount on the electrospinning, pyrolysis, phase formation and the properties of the resulting C-rich ceramic nonwovens was evaluated. The fiber diameter after pyrolysis at 1000 °C ranges from 0.26 to 0.63 µm. The oligosilazane/PAN-derived ceramic nonwovens contain high oxygen and carbon content because of high reactivity leading to a high ceramic yield due to additional crosslinking. A higher initial oxidation temperature compared to pure carbon was confirmed for all samples. However, the best result was achieved with a sample based on a high proportion of polysilazane in combination with PAN, as a dense passivating layer to protect the free carbon regions was obviously better able to form.

In-situ torrefaction-densification approach for pelletizing of rice hull/rice stalk and the combustion behavior analysis

The utilization of biomass resources could optimize the energy consumption structure and achieve the goal of carbon neutrality. Torrefaction and densification pretreatment could improve the defects of high oxygen content, low energy density, and low bulk density of biomass. In this work, high-density and hardness pellets were prepared by torrefaction coupling densification (in-situ torrefaction-densification without binders). In-situ torrefaction-densification significantly reduced the pressure required for the densification process. In-situ torrefaction-densification lowered the pressure required to prepare RH pellets with a bulk density of 1000 kg/m3 from 88.23 MPa to 30.95 MPa. The effects of the in-situ torrefaction-densification method and pelletizing pressure on the pellet combustion process were investigated by non-isothermal and isothermal combustion. The volatile and carbon of TCDP could be burned intensively during combustion, and the emissions of CO and CxHy were reduced during combustion. The original structural strength of TCDP was still maintained in the combustion process. The alkali metal K in TCDP was difficult to escape, effectively reducing the emission of K in the flue gas. In-situ torrefaction-densification could not only improve the quality of biomass solid fuel but also facilitate the storage and transportation of biomass solid fuel.

A method to synthesize ultrafineTiB2 and ZrB2 powders

In this work, the ultrafine TiB2 and ZrB2 powders were prepared using TiO2, ZrO2, C, B4C, and Ca as the raw materials. The process consisted of steps of carbothermic pre-reduction of oxide, boronization and decarburization reactions in Ca melt, wet leaching as well as deep deoxidation. The pre-deoxidation by carbothermic reduction successfully avoids the problem of evaporation loss of boron source in traditional borothermal reduction method to prepare borides due to the generation of boride oxide. Because of the strong exothermic behavior, the adiabatic temperatures in boronization-decarburization step as well as wet leaching step were calculated, and the results show that these reactions are mild and controllable. Furthermore, it was found that the high oxygen contents in as-prepared TiB2 and ZrB2 powders were resulted from the high temperature and low pH value during water leaching and acid leaching processes. After deep deoxidation at 1673 K in vacuum by mixture of C and B4C, the particle sizes of the final TiB2 and ZrB2 powders were about 200 nm, and the oxygen contents were 1.26 wt% and 0.92 wt%, respectively.

Assembly of 1D Helical Energetic Coordination Polymers Using a Flexible Bridged Furazan-triazole Cation.

Two new energetic coordination compounds with 1D helical chain structures have been synthesized. First, the polyamine precursor 4,5-diamino-2-((4-amino-1,2,5-oxadiazole-3-yl)methyl)-2,4-dihydro-3H-1,2,4-triazole-3-imino chloride salt (TATAF-Cl) is obtained by incorporating 4-(chloromethyl)-1,2,5-oxadiazol-3-amine with 4H-1,2,4-triazole-3,4,5-triamine. Using a simple hydrothermal method, two energetic complexes, Ag(TATAF)(ClO4)2 (ECP-1) and Ag(TATAF)(NO3)2·H2O (ECP-2), with a helical 1D MOF structure of furazan and triazole were synthesized. Compounds ECP-1 and ECP-2 have relatively high nitrogen and oxygen content (N + O%: 52.04%, 61.04%), excellent crystal density (2.229 g cm-3, 2.116 g cm-3 at 298 K) and high heat of detonation (1.18 kcal g-1, 1.06 kcal g-1), good detonation performance (P: 35.34 GPa, 29.52 GPa; Dv: 8412 m s-1, 7794 m s-1), and moderate sensitivity (IS: 8 J, 13 J; FS: 72 N, 64 N). Structurally, the Ag+ of the two ECPs is coordinated with two energetic cations, two perchlorates, or one nitrate via tetragonal coordination to form a single helical structure that is interspersed up and down in two directions.

Preparing carbonated water-bio-heavy oil emulsions via membrane emulsification for efficient interphase mass transfer desalination

Bio-heavy oil with high oxygen content and combustion calorific value has attracted lots of attention as a green and sustainable fuel to cope with the increasingly severe energy shortages. However, the high salt content limits its combustion utilization due to potential risks such as equipment corrosion and wear blockage. The traditional desalination method using sulfuric acid causes a large amount of wastewater, Herein, we propose an assisted metal-ion interphase mass transfer desalination strategy by preparing carbonated water-in-bio-heavy oil (CW/O) emulsions with continuous membrane emulsification. α-Al2O3 membrane with an average pore size of 600 nm was selected as the emulsification medium. Saturated carbonic acid solutions as a dispersed phase were pressed through the membrane pores into bio-heavy oil to form uniform micron-sized CW/O emulsions. The prepared CW/O droplets provide a large interphase mass transfer interface which assists the hydrolysis of fatty acid salts of bio-heavy oil in the acidic environment and yields an efficient transfer of metal ions. As a result, the CW/O emulsion with an average droplet size (D3,2) of 4.29 μm and a specific surface area of 139.63 m2/m3 was prepared at a pressure of 0.5 MPa, achieving a salt removal efficiency of up to 85.62 %. This study provides a novel chemical-free and effective strategy for efficient oil product refining while utilizing CO2 through the continuous preparation of micron-sized CW/O droplets with sufficient interphase mass transfer area.

Effects of Solution pH on Chemical Bath Deposited Iron-Sulfide-Oxide with Tartaric Acid Presence

A chemical bath deposition (CBD) contained sodium thiosulfate (Na2S2O3), iron (II) sulfate heptahydrate (FeSO4.7H2O), and L(+)-tartaric acid (C4H6O6) as the complexing agent has been used to deposit the iron-sulfide-oxide (FeSxOy) films. The effects of different solution pH (5.0-9.0) on film properties were investigated. The thicknesses of the film analysed from the cross-sectional images of Scanning Electron Microscopy (SEM) showed the thickness of the film is increasing with increasing pH. The X-Ray Diffraction (XRD) pattern and the hot probe method revealed that all the deposited films are crystalline, and possess n-type semiconductor behaviour due to high oxygen content (around 72-82%). Larger crystallite sizes with extra peaks of goethite and hematite were present for the films with pH > 7.0, while, better film uniformity and grains distribution, as well as clear absorption edge in transmittance measurement, were obtained for the film with pH 5.0.

Sorption of four antibiotics onto pristine biochar derived from macadamia nutshell

In this study, the sorption properties of ciprofloxacin, ofloxacin, sulfamethoxazole, and trimethoprim on biochar derived from macadamia nut shells were investigated. The raw biomass was pyrolyzed at 600 °C to create a highly porous material with a surface area of 392 m2 g−1. The produced biochar was found to be a valuable material for both environmental remediation and carbon sequestration due to its high carbon and oxygen content. The sorption properties of four antibiotics on the produced biochar were compared using Bayesian nonlinear regression based on second-order kinetics and the Langmuir model. The Bayesian estimation successfully compared the adsorption coefficients of the antibiotics, which can be directly visualized through graphical grammar using the probability density distribution. The results demonstrated the ability of macadamia nut shell biochar to remove antibiotics from water at neutral pH, and this material has the potential to be used for treating other emerging contaminants.

Experimental and numerical investigation of methane combustion in a HCCI engine under enriched oxygen conditions

The challenge in the energy transition lies in the intermittent nature of renewable energy, requiring the development of effective storage methods. E-fuels are considered a promising solution, with potential applications to Homogeneous Charge Compression Ignition (HCCI) engines known for their high thermal efficiency and low nitrogen oxide emissions. However, HCCI engines face limitations such as low power density and a narrow operating range. To overcome these issues, oxygen-enriched combustion is proposed, aiming at enhancing the mixture reactivity and expanding the operating range by decreasing the intake temperature. As the potential of the expansion of the operating range has never been investigated, we performed an experimental campaign using a methane-fuelled HCCI engine at variable oxygen fractions in the oxidizer. To further elucidate the effects of oxy-fuel combustion, we also performed a kinetic analysis of the reactions driving the combustion behaviour. It has been experimentally found that increasing the oxygen content in the mixture, up to 90%, has a significant potential to decrease the needed intake temperature (up to 70 °C) of the charge to keep the Maximum Pressure Rise Rate (MPRR) below the safety threshold of 8 bar/CAD. Despite the notable IMEP increase achieved, operating the engine at high oxygen content presents significant technical challenges. Therefore, to make HCCI engines competitive with other combustion modes, it is essential to combine oxygen enrichment with additional power density enhancement techniques. The kinetic analysis has highlighted that the mixture is less sensitive to intake temperature changes at higher oxygen percentages (above 50%) and that the rates of the main reactions involved in methane and OH consumption are highly enhanced by oxygen addition.

Pyrolysis of Laminaria japonica with biochar production and its characteristics

In the present paper, biochar from the Laminaria japonica from brackish lagoons (Sea of Okhotsk, Sakhalin Island) was obtained by a stepwise pyrolysis at 500 °C. The properties of concerned biochar (elemental composition, specific surface area, particle size distribution) were studied. It was shown that the Laminaria japonica biochar has 0.2–18 μm particle sizes with a complex branched surface of high microporosity and a specific surface area of 38.6 m2g-1. Aforementioned biochar has the high content of carbon (~60 at%) and high content of oxygen (~34 at.%).

Selective C(aryl)-O bond cleavage in biorenewable phenolics.

Biorefining of lignocellulosic biomass via a lignin first approach delivers a range of products with high oxygen content. Besides pulp, a lignin oil rich in guaiacols and syringols is obtained bearing multiple C(aryl)-OH and C(aryl)-OMe groups, typically named phenolics. Similarly, technical lignin can be used but is generally more difficult to process providing lower yields of monomers. Removal of the hydroxy and methoxy groups in these oxygenated arenes is challenging due to the inherently strong C-O bonds, in addition to the steric and electronic deactivation by adjacent -OH or -OMe groups. Moreover, chemoselective removal of a specific group in the presence of other similar functionalities is non-trivial. Other side-reactions such as ring saturation and transalkylation further complicate the desired reduction process. In this overview, three different selective reduction reactions are considered. Complete hydrodeoxygenation removes both hydroxy and methoxy groups resulting in benzene and alkylated derivatives (BTX type products) which is often complicated by overreduction of the arene ring. Hydrodemethoxylation selectively removes methoxy groups in the presence of hydroxy groups leading to phenol products, while hydrodehydroxylation only removes hydroxy groups without cleavage of methoxy groups giving anisole products. Instead of defunctionalization via reduction transformation of C(aryl)-OH, albeit via an initial derivatization into C(aryl)-OX, into other functionalities is possible and also discussed. In addition to methods applying guaiacols and syringols present in lignin oil as model substrates, special attention is given to methods using mixtures of these compounds obtained from wood/technical lignin. Finally, other important aspects of C-O bond activation with respect to green chemistry are discussed.

Highly stable poly-nitro components achieved through supramolecular encapsulation

As representatives of poly-nitro oxidant components, dinitramide [−N(NO2)2, DN] and nitroformate [−C(NO2)3, NF] exhibit a very large potential as energetic materials given their highly available oxygen content.

Structure and performance regulation of energetic complexes through multifunctional molecular self-assembly.

The design of novel energetic compounds constitutes a pivotal research direction within the field of energetic materials. However, exploring the intricate relationship between their molecular structure and properties, in order to uncover their potential applications, remains a challenging endeavor. Therefore, employing multi-molecule assembly techniques to modulate the structure and performance of energetic materials holds immense significance. This approach enables the creation of a new generation of energetic materials, fueling research and development efforts in this field. In this study, a series of coordination compounds are synthesized by utilizing tetranitroethide (TNE) as an anion, which possesses a high nitrogen and oxygen content. The synthesis involves the synergistic modification between metal ions and small molecule ligands. Characterization of the obtained compounds is carried out using various techniques, including single crystal X-ray diffraction, IR spectroscopy, elemental analysis, and simultaneous TG-DSC analysis. Additionally, the energy of formation for these compounds is calculated using bomb calorimetry, based on the heat of combustion. The detonation performances of the compounds are determined through calculations using the EXPLO 5 software, and their sensitivities to external stimuli are evaluated.

Comparison of lignocellulosic-based biomass pyrolysis processes by multi-scale molecular characterization

Nowadays, biomass is considered one of the key solutions for the energy transition as a renewable energy source. It can be converted by pyrolysis into bio-oil, which can be used for producing biofuels or valuable chemicals. However, bio-oils produced from pyrolysis present high oxygen content and it is necessary to use advanced pyrolysis processes to improve the quality of the bio-oils. In this study, three bio-oils produced by different pyrolysis processes: fast pyrolysis (FP), catalytic fast pyrolysis (CFP), and reactive catalytic fast pyrolysis (RCFP) were analyzed using different analytical techniques. A first bulk analysis was performed using proximate and ultimate analysis and gel permeation chromatography with refractive index and UV detection (GPC-RI and GPC-UV), which provided crucial information on the elemental composition and mass distribution of the bio-oil components. A deeper investigation at the molecular level was performed using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICR MS) and High-Performance Thin Layer Chromatography (HPTLC) to determine detailed molecular classification of the bio-oil components. Finally, a fractionation method using flash chromatography (FC) was used to provide a more accurate chemical description. The obtained fractions were analyzed by two-dimensional "comprehensive" gas chromatography (GC×GC) coupled with mass spectrometry (MS) and flame ionization detector (FID), HPTLC, and FTICR MS. The results show that the bio-oils produced from FP and CFP are very similar chemically spoken. The bio-oil from RCFP has less oxygenated products and more unsaturated hydrocarbon species. Therefore, RCFP process was found to be the best process for producing oils with a low O/C ratio.

In-situ preparation of high oxygen content titanium via wire arc additive manufacturing with tunable mechanical properties

High oxygen content titanium (HOC-Ti) was manufactured in-situ via wire arc additive manufacturing (WAAM), and its compositional segregation, microstructure and mechanical properties were studied. The results show that the microstructure of the HOC-Ti component is mainly manifested as acicular α colonies. As oxygen content increases, the acicular α of the sample is broadened and the colonies become larger. Due to the strengthening of oxygen and the grain size effect, the strength change trend is from high to low, and the elongation is reduced significantly. The fracture mechanism is changed from ductile rupture to cleavage fracture. When the oxygen content is 0.37 wt.%, its elongation is about 7%, andthe ultimate tensile strength is more than 730 MPa, which is around double that of commercially pure titanium (CP-Ti).

Properties of Mixed Crystal Coprecipitation Substances of Ammonium Nitrate and Potassium Perchlorate Prepared by the Evaporative Solvent Method.

Ammonium perchlorate (AP) has been widely used as an oxidizer in propellants and military mixed explosives in recent years. However, its high characteristic signal, environmental pollution, and poor detonation performance have prompted the industry to seek alternatives to AP. Ammonium nitrate (AN) is a suitable substitute due to its low characteristic signal, lack of pollution, and excellent detonation performance. However, its room-temperature phase transition and hygroscopicity affect its practical use. In this work, we prepared mixed crystal coprecipitation (MCC) materials of AN and potassium perchlorate (KP) using the evaporative solvent method. The characterization of AN/KP MCCs was carried out by combining TG-DSC, XRD, FT-IR, and SEM analysis, revealing that the formation of MCCs by AN and KP is due to ion exchange between the two components. AN/KP MCCs not only solve the problem of room-temperature phase transition in AN but also reduce its hygroscopicity. Furthermore, AN/KP MCCs have mechanical sensitivity, explosive performance, and specific impulse similar to pure AN, but compared to AN, AN/KP MCCs have higher density, effective oxygen content, and thermal stability. Compared with existing oxidizers AN, AP, and KP, AN/KP MCCs with high density, low sensitivity, high oxygen content, and high safety have obvious advantages and have good prospects in the application of oxidizers in solid propellants and military mixed explosives.

Catalytic aqueous hydrodeoxygenation of palmitic acid with in-situ hydrogen donor

Algal bio-oil obtained from hydrothermal liquefaction of algae contains a large amount of water and long-chain fatty acids. High acidity and corrosiveness seriously restrict the application of algal bio-oil. The aqueous-phase catalytic upgrading was a promising approach to solve this problem, and the hydrogen donor was one of the most important parameters to the conversion of the algal bio-oil and the quality of the products. Catalytic transfer hydrogenation (CTH) reaction was an efficient, economical and green method for hydrogenation reaction, which can directly transfer hydrogen from the hydrogen donor to the reaction substrate. In this work, the CTH reaction of algal bio-oil model compound palmitic acid was investigated to deal with the problem of high oxygen content in the algal bio-oil. Several common hydrogen donors, included methanol, ethanol, formic acid, and isopropanol, as well as different reaction conditions were experimented to study the CTH process of palmitic acid. The results showed that, with the reaction conditions of 350 °C and 10 h, formic acid achieved the best oxygen removal, carbon retention and energy efficiency, the C16 selectivity reached the highest at 33.3 % as the formic acid addition ratio was 1:2, and the C15 selectivity reached the highest at 48.3 % as the formic acid addition ratio was 1:3. In general, the best ratio of formic acid added was 1:3, which showed the highest yield of C15 and above alkanes of 79.6 %. This result indicates that the catalytic transfer hydrogenation reaction of formic acid has practical value in improving the combustion performance of algal bio-oil.