Decomposition Of Hydrocarbons Research Articles

Salting out and vortex-assisted dispersive liquid–liquid microextraction based on solidification of floating organic drop microextraction (SO-VADLLME-SFODME) for extraction and determination of polycyclic aromatic hydrocarbons (PAHs) in water and solid samples followed by HPLC

In this research the possibility of application of an innovative, simple, economical, selective ability and green (environmentally friendly) method of salting out and Vortex-Assisted dispersive liquid-liquid microextraction based on solidification of floating organic drop by using high performance liquid chromatography with containing UV for pre-concentration, the extraction and determination of polysiclic in water and solid samples followed by HPLC was studied. In this method three integrated and combined approaches have been adopted so as to maximize the advantages of the approach used while minimizing their disadvantages. The effects of experimental variables such as pH, the type and volume of dispersive extracting solvents (μl, pH), the volume of organic drop microextraction (extracting solvent), salt density (concentration), centrifuge condition (time), extraction time and temperature were examined, and the process of optimization was obtained by using a software based on Response Surface Methodology (RSM) and Box-Behnken design [as the experimental model] and Desirability Function (DF). This method has appropriate linear calibration between 0.2 to 800μg/L, and a significant limit of detection coefficient (r2> 9991) and low detection range (between 0.05 to 0.09 μg/L). The above method was also applied for the successful determination of polycyclic aromatic hydrocarbons in industrial was water, water and soil samples PAHs) and the percentage of recycling, repeatability and reproducibility, resulting in satisfactory results. Simplicity, being economical, quickness, proper repeatability, less consumption of organic solvent and efficient decomposition are of the principal advantages (merits) of the proposed method for the decomposition and determination of polycyclic aromatic hydrocarbons (PAHs) in water samples.

A study of the photocatalytic properties of chitosan-TiO2 composites for pyrene decomposition

In this work, nano- and microcomposites of chitosan-TiO2 were developed for the photocatalytic decomposition of pyrene, which is one of polycyclic aromatic hydrocarbons. TiO2 nanoparticles were synthesized by laser ablation, and their sizes were determined using the photon correlation spectroscopy method. Nano- and microcomposites based on chitosan with different TiO2 particle contents were manufactured. The work studies the effect of nano- and microparticles of TiO2 in the composition of manufactured nanocomposites on the photodegradation of pyrene in model solutions of dimethyl sulfoxide under ultraviolet radiation. To assess the decrease in pyrene concentrations in solutions, the authors used the method of luminescent analysis. Based on the results of the conducted studies, pseudo-first-order kinetic graphs for pyrene degradation in solutions were plotted. The analysis proves the efficiency of the obtained chitosan-TiO2 composites for the photocatalytic decomposition of pyrene. In 60 minutes, 68 % and 55 % of pyrene were photodegraded under ultraviolet irradiation using chitosan-TiO2 composites with TiO2 nanoparticles and with TiO2 microparticles, respectively. The developed chitosan-TiO2 composites are prospective photocatalytic materials for the decomposition of polycyclic aromatic hydrocarbons in aqueous media. The method of manufacturing composites does not require expensive equipment, and they are also convenient for performing photocatalytic reactions.

Emission of soot particles from the combustion of various fuels in boilers

According to modern estimates, the largest contribution to global warming is made by carbon dioxide, while its share is 60-70%. However, studies of the last decade also indicate a large impact on the planet’s climate of “short-lived climate pollutants”, which mean forcing substances with “lifetimes” in the atmosphere from several days to several years. These pollutants include black carbon. In the Russian Federation, black carbon refers to the substance “carbon (soot)”, which is a dispersed carbon product of incomplete combustion or thermal decomposition of hydrocarbons, consisting of particles of various shapes and having a black color. Soot is a strong carcinogen. It is the 2nd class harmful substance and carried by winds for thousands of kilometres. It has been found that black carbon retains several hundred times more heat than carbon dioxide does. Therefore, reducing black carbon emissions is one of the most important challenges in the fight against climate change. Therefore, the task arises of a comprehensive study of all aspects related to black carbon emissions. Based on this, experimental studies of the emissions of soot particles formed in the combustion chambers of boilers of various capacities and designs were carried out during the combustion of various solid, liquid and gaseous fuels. The structure, size and quantitative composition of soot particles, as well as their constituent elements, were studied using scanning electron microscopy. The research results made it possible to propose a more extended approach for choosing the values of specific soot emissions from the combustion of various fuels in heat generators, which should be used in the inventory of emissions of this pollutant.

Fuel reformation by piston compression of rich air-fuel mixture

The purpose of this paper is to investigate and describe the fuel reformation by diesel piston compression to change the ignitability of commercial fuels for marine engines. The engine operational conditions were first investigated by CHEMKIN Pro with n-heptane as a fuel, an HCCI engine with port fuel injection was operated by n-heptane based on simulation results, and the production of reformed gases (hydrogen, carbon monoxide, methane, and ethylene) were measured by emission analyzers. The fuel reformation becomes active above a 2.0 equivalence ratio and higher intake air temperature conditions, and the molar fractions of the reformed gases can be varied by the maximum in-cylinder average temperature during the reforming processes. An indirect injection diesel engine was newly introduced and the diesel fuel reformation characteristics were evaluated. Further, the fuel decomposition processes were investigated by CHEMKIN Pro. The results suggest that the hydrogen and carbon monoxide are produced via a number of production paths in the fuel decomposition into small hydrocarbons and chemical production controls of hydrogen and carbon monoxide will be difficult. However, the production paths of methane and ethylene formation are limited by the decomposition of hydrocarbons and this suggests the possibility of chemical production control of methane and ethylene.

Hydrogen Evolution from Hydrocarbon Pyrolysis in a Simulated Liquid Metal Bubble Reactor

The evolution of hydrogen from methane decomposition in a liquid metal bubble reactor (LMBR) has become a recent subject of interest; this study examines a novel approach to hydrogen production from pyrolysis of complex hydrocarbon fuels. Modeling hydrocarbon fuel decomposition in an LMBR is executed in two stages of pyrolysis: First, primary pyrolysis intermediates are simulated using a functional-group-based kinetic model (FGMech). Then, a detailed high temperature mechanism (AramcoMech 1.3 + KAUST PAH + 5 solid carbon chemistry) is applied to simulate secondary pyrolysis of intermediates. The quantities of major products of the secondary pyrolysis simulation (CH4, H2, Cs, C6H6) are approximated by simplified regression equations. Further decomposition of smaller hydrocarbons (until exiting the reactor) is simulated using a coupled kinetic and hydrodynamics model that has been reported in the literature. The mixing effects of bubble coalescence and breakup are investigated in a comparative study on homogeneous and non-homogeneous reactors. Finally, a qualitative relationship between H2 yield per mass of fuel, functional group, and other factors such as temperature, pressure, and residence time is analyzed. In general, the H/C ratio and cyclic/aromatic content are the main features influencing total conversion to H2.

Optimization of electrokinetic pretreatment for enhanced methane production and toxicity reduction from petroleum refinery sludge

This study examined the effect of electrokinetic pretreatment on petroleum sludge (PS) released from the wastewater treatment plants of petrochemical industries for enhanced biodegradation and contaminant removal. The application of electric field on PS through direct current is optimized with the combined variation of applied voltage (40–80 V), exposure duration (20–120 min) and distance between graphite electrodes (8–16 cm) using central composite design-response surface methodology (CCD-RSM). The optimization study revealed significant interaction among the response variables to obtain an optimum condition (60 V, 83.5 min, 11.6 spacing) for maximization of solubilization in terms of soluble chemical oxygen demand (230% increment against untreated) and volatile fatty acids (172% increment against untreated) concentrations for accelerated hydrolysis of complex PS. BMP batch assays were performed at different inoculum and sludge ratios (0.3, 0.4, 0.5 and 0.7) based on volatile solids content after pretreatment at the optimized condition which resulted in accumulated methane ranging from 5.16 to 6.61 L/gVSadded (untreated - 3.9 L/gVSadded). The mixing ratio of 0.4 showed the maximum methane enhancement of 69.2% compared to untreated. The maximum removal of organic content (62.8%), oil and grease (71.74%), and total petroleum hydrocarbon (52.9%) were also observed for the mixing ratio of 0.4. The FTIR study showed the efficacy in hydrocarbon dissociation and decomposition after pretreatment of PS. The net energy gain (3508 kJ) and phytotoxicity reduction of batch digestate after the anaerobic digestion suggest the economic feasibility and decontamination efficiency of the electrokinetic pretreatment technique respectively. Further research could be performed to evaluate the viability of this pretreatment for enhanced methane recovery at field-scale levels to relate to these lab-scale postulations.

Reclamation of oil-induced soil hydrophobicity in the hyper-arid Evrona Nature Reserve, southern Israel

Two oil spills occurred in the Evrona Nature Reserve (southern Israel), in 1975 and 2014. This oil contamination induced highly persistent soil hydrophobicity. The objective of this study was to investigate the decrease in oil-induced soil hydrophobicity under different environmental conditions and to assess the relationship between the hydrophobicity and hydrocarbon content. A laboratory incubation experiment was conducted over 1.5 years to monitor the soil hydrophobicity and total hydrocarbon concentration under different environmental conditions. We hypothesized that the addition of water (20% or 50% saturation), nutrients, and biosurfactants can accelerate the reduction in hydrophobicity and decomposition of hydrocarbons. Water drop penetration time and molarity of ethanol droplet tests were used to assess soil hydrophobicity. In parallel, alkane composition and total petroleum hydrocarbons were evaluated to indicate oil attenuation. The addition of water, nutrients, and biosurfactants resulted in a concomitant reduction in hydrophobicity and hydrocarbon concentration of varying degrees, exhibiting enhanced degradation and hydrophobicity reduction observed in treatments to which nutrients and biosurfactants were added. At the end of the incubation, however, soil hydrophobicity in all treatments remained severe, even though total petroleum hydrocarbon removal was fairly high and reached 40%–80% in the treatments to which water with or without nutrients and/or surfactants was added.

Carbon Microstructures Synthesis in Low Temperature Plasma Generated by Microdischarges

The aim of this paper is to investigate the process of growth of different carbon deposits in low-current electrical microdischarges in argon with an admixture of cyclohexane as the carbon feedstock. The method of synthesis of carbon structures is based on the decomposition of hydrocarbons in low-temperature plasma generated by an electrical discharge in gas at atmospheric pressure. The following various types of microdischarges generated at this pressure were tested for both polarities of supply voltage with regard to their applications to different carbon deposit synthesis: Townsend discharge, pre-breakdown streamers, breakdown streamers and glow discharge. In these investigations the discharge was generated between a stainless-steel needle and a plate made of a nickel alloy, by electrode distances varying between 1 and 15 mm. The effect of distance between the electrodes, discharge current and hydrocarbon concentration on the obtained carbon structures was investigated. Carbon nanowalls and carbon microfibers were obtained in these discharges.

Production of Hydrogen and Carbon Nanofibers by the Catalytic Decomposition of Methane over Ni-Containing Catalysts

This paper is devoted to technology for producing pure hydrogen by catalytic decomposition of light hydrocarbons. A set of nickel-containing catalysts was prepared using the corresponding salts. The content of active metal (Ni) varied from 10 to 90 wt %. The activity of the catalyst in the process of methane decomposition was studied. It has been found that the most promising method for the synthesis of catalysts is the melting of salts of metal. The maximum yield of hydrogen was 416 L/gcat at a Ni content of 90 wt % at a temperature of 675 °C and a pressure of 5 atm.

Biological treatment of PAHs using genetically modified local bacterial isolates

Bioremediation technology by microorganisms, which already presents in the contaminated soils, is considered one of the primary mechanisms by which petroleum and other hydrocarbon pollutants can be removed from the environment. Twelve decomposing bacterial isolates were isolated from three polluted sites (Al-Dora oil refinery, Middle Refineries Company from oil wells, and Karbala oil refinery). This study showed high efficacy polycyclic aromatic hydrocarbons (PAHs) of isolated bacteria appropriate to polycyclic aromatic hydrocarbons decomposition. Primary and secondary screening of bacterial isolates has been performed using experiments based on the colour change in the medium resulting from the degradation of hydrocarbons in the nutrient medium. The screening results were three isolates that were characterized according to the basis of morphological and biochemical features and verified by Vitek 2, Pseudomonas aeruginosa, Escherichia coli and Sphingomonas paucimobilis. The mutagenesis process has been carried out by UV irradiation with a wavelength of 254 nm on selected bacterial strains. Experiments have been conducted on PAHs (naphthalene, phenanthrene and acenaphthene. According to the Biodegradation Efficiency result for 28 days, the best phenanthrene degrading bacteria was (Pseudomonas aeruginosa wild type (73.4%), Escherichia coli wild type (71.5%) and Sphingomonas paucimobilis wild type (68.8%). For naphthalin metabolism, the best degradation efficiency was (Pseudomonas aeruginosa wild type (86.2%), Sphingomonas paucimobilis wild type (69%) and Escherichia coli wild type (63%). At the same time, acenaphethene great degradation efficiency was Sphingomonas paucimobilis wild type (72%), Pseudomonas aeruginosa wild type (71%) and Sphingomonas paucimobilis mutant type (66%). We conclude that random mutation’s effect did not increase the degradation ability for most bacterial isolate.

Pyrolysis of predried dyeing sludge: Weight loss characteristics, surface morphology, functional groups and kinetic analysis

AbstractThe weight loss characteristics, surface morphology, functional group, and kinetic parameters of predried dyeing sludge (PDS) pyrolysis was studied for the first time in this paper. The contents of both volatile matter and organic matter in PDS char both decreased with the increase of pyrolysis temperature. The PDS pyrolysis process can be divided into four stages: S1 (30°C‐180°C)—water evaporation, S2 (180°C‐500°C)—decomposition of organic compounds such as aliphatic compounds and biomass fibres, S3 (500°C‐900°C)—decomposition of the former stage residues, and S4 (900°C‐1350°C)—decomposition of carbonaceous material remaining in the char and vaporization of partial ash. With the increase of pyrolysis temperature, the number density of small spherical particles on the PDS particle surface increased. The decomposition of aliphatic hydrocarbon was basically completed at 700°C. The average activation energy of PDS in S2‐S4 stages were 172.93, 445.65, and 301.76 kJ/mol, respectively. The pyrolysis reaction of PDS samples could be described by nth‐order reaction mechanism function.

In situ kinetic studies of CVD graphene growth by reflection spectroscopy

• In situ metrology system for graphene growth based on reflectance spectroscopy. • Evolution of a microkinetic model for microscopic understanding of growth process. • Investigation of hydrogen role during graphene growth. Controllable large-scale synthesis of two-dimensional materials (2DMs) such as graphene is a prerequisite for industrial applications. Chemical vapor deposition (CVD) is currently the most widespread synthesis method as it is efficient and easy to automatize. The process itself is quite complex and poorly understood, but it is generally believed to involve a number of distinct steps such as hydrocarbon decomposition into surface-bound intermediates, diffusion on the catalytic substrate, generation of nucleation points and, finally, graphene growth. In situ monitoring and tailoring of such a complex procedure is beneficial for understanding the growth kinetics and, eventually, for controlling the graphene growth. Herein, we report on a novel metrology system based on in situ reflectance spectroscopy that has been developed for real-time monitoring of surface changes during graphene growth on Cu foils at high operating temperatures. The implementation of this technique for extracting kinetic parameters of the growth process is presented. Furthermore, a microkinetic model of graphene growth based on density-functional theory (DFT) and the hindered translator / rotator model for enthalpy and entropy corrections is constructed and used to obtain a microscopic understanding of the apparent activation energy and related rate-determining steps in graphene growth.

Bioremediation Of Soil Of The Kola Peninsula (Murmansk Region) Contaminated With Diesel Fuel

This work focuses on the creation and use of associations of hydrocarbon-oxidizing microorganisms. Bioremediation of soils with the help of mixed cultural and associations of microorganisms provides wider adaptive possibilities than individual species. This is especially important in conditions of short northern summer. The results of field experiments showed that microbial associations based on indigenous microorganisms (bacteria Pseudomonas fluorescens, P. putida, P. baetica, Microbacterium paraoxydans and fungi Penicillium commune, P. canescens st. 1, P. simplicissimum st. 1) with mineral fertilizers reduced the content of total petroleum hydrocarbons in the Hortic Arthrosol soil of the Kola Peninsula by 82% over 120 days. Also, the microbial associations with mineral fertilizers had a positive effect on the physical properties of the soil, increasing its humidity. The bacterial-fungi associations changed the number, abundance and structure of the indigenous community of microorganisms. Penicillium canescens, which was included in the composition of fungi association, became dominant. During the rapid decomposition of hydrocarbons are released to the soil toxic intermediates or metabolites of the microbial oxidation of hydrocarbons. Hydrocarbon oxidizing microfungi suppressed the germination of test plant seeds to one degree or another. Penicillium commune fungal metabolites inhibited seed germination only by 29% for Lepidium sativum L. and 24% for Triticum aestivum L. This species can be used for bioremediation of petroleum contaminated soils.

The Possibility of Using the Existing Large-Sized Equipment of the Units when Switching to New Oil Treatment Technologies

Oil treatment at field stabilization units allows preparing oil for storage and transportation, including by reducing the RVP and hydrogen sulfide content in oil. However, the use of direct fire heating of oil in pipe stills to maintain the thermal regime in the stabilization column may cause the formation of secondary hydrogen sulfide as a result of the thermal decomposition of heavy sulfur-containing hydrocarbons, which leads to additional financial losses for bringing the stabilized oil to the requirements of the current regulatory documents. A way to reduce the amount of secondary hydrogen sulfide is the transition from direct fire heating of oil to heating through an intermediate high-temperature coolant. In this case, the thermal regime of the stabilization column operation is maintained by heating in the reboiler, while it remains possible to use the existing unit columns and stills without their significant retrofitting.

Evaluation on explosibility of pulverized coal in air atmosphere based on functional group structure analysis

Explosion performance of single bituminous pulverized coals (PCs) and interaction between anthracite (AT) and bituminite (BT) in blends with various anthracite proportions were studied by measuring the length of backflow flame. The results indicated that explosibility of BTs was closely related to its functional group structure, while the influence of volatile content on explosibility of PCs was insignificant. Aliphatic hydrocarbons were observed to be more explosive comparing to aromatic hydrocarbons, while the reaction behavior of char was also dominant during the explosion of PC. Besides, the high heating value of char in BTs ranged from 29 and 30 kJ/g, while that of anthracite was decreased after pyrolysis for the volatile matters in anthracite were of higher heating value. The kinetic analysis based on random pore model implied that the activation energy of volatile was closely related to the value of apparent aromaticity, while the condensation degree of aromatic hydrocarbons was more critical for that of char. The decomposition of light volatiles would just lead to the formation of penetrating cracks, while the decomposition and oxidation of aliphatic and aromatic hydrocarbons were destructive to the microstructure of PC particle.

Selected Aspects of Hydrogen Production via Catalytic Decomposition of Hydrocarbons

Owing to the high hydrogen content, hydrocarbons are considered as an alternative source for hydrogen energy purposes. Complete decomposition of hydrocarbons results in the formation of gaseous hydrogen and solid carbonaceous by-product. The process is complicated by the methane formation reaction when the released hydrogen interacts with the formed carbon deposits. The present study is focused on the effects of the reaction mixture composition. Variations in the inlet hydrogen and methane concentrations were found to influence the carbon product’s morphology and the hydrogen production efficiency. The catalyst containing NiO (82 wt%), CuO (13 wt%), and Al2O3 (5 wt%) was prepared via a mechanochemical activating procedure. Kinetics of the catalytic process of hydrocarbons decomposition was studied using a reactor equipped with McBain balances. The effects of the process parameters were explored in a tubular quartz reactor with chromatographic analysis of the outlet gaseous products. In the latter case, the catalyst was loaded piecemeal. The texture and morphology of the produced carbon deposits were investigated by nitrogen adsorption and electron microscopy techniques.

Assessment of Ecological Condition of Haplic Chernozem Calcic Contaminated with Petroleum Hydrocarbons during Application of Bioremediation Agents of Various Natures

Petroleum hydrocarbon contamination disrupts ecological and agricultural soil functions. For their restoration, bioremediation agents of various natures are used (nonorganic or organic fertilizers, bacterial preparations, adsorbing agents) featuring different remediation mechanisms (adsorption or biostimulation of petroleum hydrocarbon decomposition). The objective of this research is the assessment of the ecological condition of petroleum hydrocarbon-contaminated Haplic Chernozem Calcic after the application of bioremediation agents of various natures. The influence of glauconite, nitroammophos, sodium humate, the bacterial preparation “Baikal EM-1”, and biochar on the intensity of petroleum hydrocarbon decomposition and the ecological condition of Haplic Chernozem Calcic was analyzed. The ecological condition of Haplic Chernozem Calcic was assessed based on the residual content of petroleum hydrocarbons in soil and the following biological parameters: changes in the number of soil bacteria, activity of catalase and dehydrogenases, soil respiration (CO2 emission), germinating ability, lengths of roots and shoots, and integrated index of the biological state. The minimum concentrations of residual petroleum hydrocarbons in soil were observed after the use of biochar (44% from initial content) and glauconite (49%). The biological properties of soils were affected in different ways. Soil respiration was stimulated by 3-6-fold after adding nitroammophos. Indices for the intensity of the early growth and germination of radish in soil with glauconite, sodium humate, and biochar were increased by 37–125% (p < 0.01) compared with the reference value. After the application of biochar, sodium humate, and “Baikal EM-1”, the number of soil bacteria was 66–289% higher (p < 0.01) than the reference value. At the same time, the activities of catalase and dehydrogenases were inhibited by up to 35% in variants with bioremediation agents and petroleum hydrocarbons relative to the reference values. The maximum stimulation of the biological activity (as the integrated index of the biological state (IISB)) of Haplic Chernozem Calcic was observed after applying sodium humate and biochar, with 70 and 66% (p < 0.01) increases from the reference value, respectively. Considering the net cost of bioremediation agents, the maximum cost efficiency is achieved with “Baikal EM-1”, sodium humate, and biochar: 110, 527, and 847 USD·103/ha, respectively. After using Baikal EM-1”, sodium humate, and biochar, the ecological state of Haplic Chernozem Calcic was restored.

An approach for upgrading lignite to improve slurryability: Blending with direct coal liquefaction residue under microwave-assisted pyrolysis

As the composition of direct coal liquefaction residue (DCLR) is complex and difficult to handle, more importantly its dielectric properties are excellent, it is used as consumable wave-absorbents to enhance the microwave pyrolysis of lignite for slurryability improvement. The effects of the different additions of DCLR on the evolution of pyrolysis products were studied by using gas chromatography, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and low-temperature N2 adsorption analysis. The results indicated that microwave-assisted pyrolysis with DCLR was a promising method for improving slurryability of lignite and an effective method for utilizing DCLR. The introduced DCLR accelerated the heating rate of the process of microwave upgrading lignite, facilitating the decomposition of active oxygen-containing functional groups and aliphatic hydrocarbons and then their transformation into stable ether groups and aromatic structures. In the meantime, it was converted into gaseous products, mainly composed of H2, CO, and CH4, and solid products with high quality. Additionally, the cyclization and aromatization of organic structures were improved, as well as the order degree of aromatic systems, especially with 12 wt% of DCLR added. Furthermore, the existing and newly formed structures of micropores and mesopores in the upgraded lignite (UL) were remarkably reduced with the increase of DCLR contents. The re-absorption capacity was dramatically reduced and the slurryability of UL was improved as a result of the changes in chemical properties and pore structures. The maximum solid concentration of lignite water slurry (LWS) increased from 41.73 wt% to 65.42 wt% with lower pseudo-plasticity and static stability.

Decomposition of oil refinery sludge using E+-Ozonation process for carbon source releasing and TPH removal.

To utilize carbon source and decompose the petroleum hydrocarbon substances simultaneously, adding the electrolysis to ozonation (E+-Ozonation) was employed to deal with hazardous activated petroleum waste sludge (P-sludge). It was found that E+-Ozonation could accelerate the ozone utilization and hydroxyl radical (·OH) generation rate. Soluble chemical oxygen demand (SCOD) increased around 16.3 times than the control one (from 471 to 7700 mg/L). The potential carbon source, such as the short-chain carbon of acetate and propionate, increased from 50 to 1088 mg/L and from 27 to 614 mg/L respectively, and approximately accounted for a quarter of total SCOD. Total petroleum hydrocarbon (TPH) decomposition was observed with a much higher removal rate of 84.3% simultaneously, and the substances with the function group of C=C and C-C bonds decomposed greatly. The long- and medium-chain substances in TPH were converted into the short-chain substances (90% of C28-C40 of hydrocarbons was removed, while C10-C18 increased by 13.8%). E+-Ozonation process could be one of the promising methods for P-sludge decomposition through carbon source releasing and TPH removal.

Production of thin graphite films on a dielectric substrate by heteroepitaxial synthesis

Problem statement. Development of methods for producing large-area isolated graphene under controlled conditions is an important task, which is primarily interested in the unique physical and chemical properties of graphene: high electrical and thermal conductivity, dependence of electronic characteristics on the presence of attached different radicals on the graphene surface, adjustable band gap, and high carrier mobility. Goal. It is necessary to develop regimes for producing thin graphite films on a dielectric substrate by annealing the structure (0001)Al2O3/(111)Ni/ta-C with a minimum density of defects in the crystal structure by the heteroepitaxial synthesis method. Results. The method of obtaining thin graphite films on a dielectric substrate by annealing the structure (0001)Al2O3/(111)Ni/ta-C has been tested. The method is based on the catalytic decomposition of hydrocarbons on the single crystal surface of a metal catalyst, diffusion and crystallization of carbon on the reverse side of the metal film. The surface of the obtained carbon films with a thickness significantly exceeding one atomic layer is uniform within the 5x5 mm samples. Varying the annealing temperature and time, as well as the initial amount of carbon, will further allow to control the amount of carbon involved in the formation of atomic layers. Practical significance. The described method is promising for developing a scalable technological process for obtaining largearea graphene on a dielectric substrate.