N2 Fraction Research Articles

Fluid simulation of species concentrations in capacitively coupled N2/Ar plasmas: Effect of gas proportion

A two-dimensional self-consistent fluid model and the experimental diagnostic are employed to investigate the dependencies of species concentrations on the gas proportion in the capacitive N2/Ar discharges operated at 60 MHz, 50 Pa, and 140 W. The results indicate that the N2/Ar proportion has a considerable impact on the species densities. As the N2 fraction increases, the electron density, as well as the Ar+ and Arm densities, decreases remarkably. On the contrary, the N2+ density is demonstrated to increase monotonically with the N2 fraction. Moreover, the N density is observed to increase significantly with the N2 fraction at the N2 fractions below 40%, beyond which it decreases slightly. The electrons are primarily generated via the electron impact ionization of the feed gases. The electron impact ionization of Ar essentially determines the Ar+ density. For the N2+ production, the charge transition process between the Ar+ ions and the feed gas N2 dominates at low N2 fraction, while the electron impact ionization of N2 plays the more important role at high N2 fraction. At any gas mixtures, more than 60% Arm atoms are generated through the radiative decay process from Ar(4p). The dissociation of the feed gas N2 by the excited Ar atoms and by the electrons is responsible for the N formation at low N2 fraction and high N2 fraction, respectively. To validate the simulation results, the floating double probe and the optical emission spectroscopy are employed to measure the total positive ion density and the emission intensity originating from Ar(4p) transitions, respectively. The results from the simulation show a qualitative agreement with that from the experiment, which indicates the reliable model.

One-Step Synthesis of Silicon Oxynitride Films Using a Steady-State and High-Flux Helicon-Wave Excited Nitrogen Plasma

A steady-state and high-flux helicon-wave excited N2 plasma was used to oxynitride Si substrates for the synthesis of silicon oxynitride (SiON) films. X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS) have been extensively used to characterize surface quality of the SiON films, and it is found that a large amount of nitrogen (N) can be incorporated into the films. The result of XPS depth profiles shows that the N concentration is high near the surface and the oxide/Si interface. In the UPS spectra, absence of the reappearance of surface states suggests a resistance to clustering of the oxynitride layer. The N2 flux and Ar mixture quantity can facilitate tuning of the dissociation characteristics in N2 discharge. By modulating the N2 fractions, the N+ density reaches maximum at a N2/(N2 + Ar) flow-rate ratio of 0.5, resulting in incorporation of more N atoms into the SiON films. Considering the easy control of N2 plasma, our work opens up a new avenue for achieving high-yield SiON films at low temperature.

Spectroscopic and Langmuir probe measurements of Ar-N2 mixture plasma in magnetic pole enhanced ICP source

Over the last decade, the plasma sources based on electromagnetic power absorption mechanisms have emerged for large scale semiconductor manufacturing. For this purpose inductively coupled plasmas (ICPs), helicons, electron cyclotron resonance (ECR) etc have been widely explored. Recently, new designs of ICPs have been proposed for the improvement of plasma processing reactors including ICPs enhanced by a ferromagnetic core and ICPs with multiple antennas for a uniform spread of plasma over a large processing area. Present paper deals with variation in plasma processing parameters of a low pressure Ar-N2 inductively coupled plasma source with magnetic pole enhancement (MaPE-ICP). Optical emission spectroscopy (OES) and an RF compensated Langmuir probe are employed to examine the trends of parameters including the electron density, electron temperature and electron energy probability functions (EEPFs). Moreover, Ar metastable fractions are also calculated from line ratio method using optical emission intensities of the Ar spectral lines. The variation in emission intensities of the selected lines and in metastable fractions can be related with electron densities in various parts of the EEPFs. Furthermore, at low RF powers the evolution in EEPFs from ‘bi-Maxwellian’ to ‘Maxwellian’ distribution with increasing Ar concentration in the mixture is also observed. The dissociation fraction of N2 determined by ‘advanced actinometry’ technique, based on Trace rare gas-actinometry (TRG-actinometry), is also reported. It is found that dissociation fraction increases with Ar concentration in the discharge as well as RF power and filling gas pressure.

Etching characteristics of SiC, SiO2, and Si in CF4/CH2F2/N2/Ar inductively coupled plasma: Effect of CF4/CH2F2 mixing ratio

This study investigated the etching characteristics and mechanisms of SiC, Si, and SiO2 in CF4/CH2F2/N2/Ar inductively-coupled plasmas. The investigation showed that a change in the CF4/CH2F2 mixing ratio at fixed N2 and Ar fractions in a feed gas causes a decrease in the etching rates of SiC and Si, but results in an almost constant SiO2 etching rate. Plasma chemistry was analyzed using Langmuir probe diagnostics and optical emission spectroscopy. The good agreement between the behaviors of both the SiC and the Si etching rates with a change in F atom density suggested a neutral-flux-limited etching regime for these materials. On the contrary, the SiO2 etching process appeared in the transitional regime of the ion-assisted chemical reaction and was influenced by both neutral and ion fluxes.

Characterization of extinction/reignition events in turbulent premixed counterflow flames using strain-rate analysis

We investigate extinction/reignition events in two contrasting turbulent premixed flames of the Yale turbulent counterflow flame (TCF) burner, that are both qualitatively and quantitatively different. One of the two chosen flames is a high-burning (HB) flame with a low probability of local extinction while the other flame is a low-burning (LB) flame with a high probability of local extinction. In recent work, we successfully studied the turbulent premixed flames of the Yale TCF burner using the large-eddy simulation/probability density function (LES/PDF) methods. In this present study, the main motivation is to investigate how the compositional structure of the two turbulent flames are related to that of laminar flames. To this end, steady, one-dimensional, strained, opposed-jet laminar flame calculations are performed to investigate the effect of strain rates K on the laminar counterparts of HB and LB, and to evaluate the extinction strain rates Sext for the two flames. Subsequently, a normalized distance Z is defined in terms of the mixture fraction ξ, which is calculated based on the mass fraction of N2. The scatter plots from the particle data of (a) CH2O mass fraction YCH2O*vs. progress variable p* and (b) temperature T*vs. the normalized distance Z* are quite different for the two flames with more samples close to the extinguished laminar profile for the LB flame than for the HB flame. The cell-mean profiles of T vs. Z resemble the laminar profiles at different strain rates even though the LES/PDF are non-trivially 3D and unsteady. These cell-mean profiles are used to evaluate the instantaneous equivalent steady strain rate (ESSR) S for the two flames. The cumulative distribution function (CDF) of S, conditional on S < Sext (i.e., burning samples), is somewhat similar, with the distributions being broad without a peak close to the bulk strain rate. However, comparatively, more samples of the LB flame have the ESSR values above the extinction strain rate, i.e., S > Sext. The scatter plots of the ESSR S vs. the fresh product layer thickness Δf quantify the thinning of the product layer as the strain rate S increases. The scatter for the HB flame follow the corresponding laminar profile quite closely, whereas, the thicknesses observed for the LB flame are higher compared to its laminar prediction.

Influence of pulsed power supply parameters on active screen plasma nitriding

It is well known that active screen plasma nitriding (ASPN) is driven using a pulsed D.C. power supply, due to several advantages such as improved control over temperature, nitrided layer phase composition and active species generation. In addition, the pulsed power supply helps to avoid the transition to the arc regime. The ASPN configuration in particular is preferred over conventional plasma nitriding due to complete elimination of edge effect, as plasma is not in direct contact with the samples. In this work, the influence of pulsed power supply parameters such as duty cycle, peak voltage, peak current and time averaged current is studied in an ASPN setup, on nitrided layer phase composition and surface hardness of austenitic stainless steel (ASS). In addition, optical emission spectroscopy (OES) is used to measure the excitation, vibrational and rotational temperatures (Texc, Tvib, Trot), nitrogen dissociation fraction and concentration of active species N2(C3Πu) and N2+(B2Σu+) (in terms of emission intensities) to clarify the results obtained from surface characterization. The results show that keeping time-averaged current constant, the surface hardness decreases with the duty cycle of the pulsed D.C. power supply. The results from OES and surface analysis are correlated, and as a result plasma parameters (Texc, Tvib, Trot) and active species concentration (N, N2, N2+) are found to be important precursors in surface hardening of ASS.

Syngas production from regasified liquefied natural gas and its simulation using Aspen HYSYS

This research was carried out to simulate the Syngas production unit using Aspen HYSYS with the aim of enabling regasified liquefied natural gas (R-LNG) as raw material. The simulation is based on conditions and parameters (mass flow rates, temperature and pressure readings) obtained from the Ammonia plant of the Fertilizers and Chemicals Travancore Limited (FACT). The simulation results showed that the resulting syngas composition indicated 0.2661, 0.7331, 0.0005 and 0.0003 mol fractions of N2, H2, CH4 and H2O respectively. The feed changeover from naphtha to R-LNG, which has a lower carbon/hydrogen ratio, results in the reduction of steam/carbon ratio and so reduces CO2 emission.

A comparative study of biomolecule and polymer surface modifications by a surface microdischarge

Cold atmospheric plasma (CAP) sources are attractive sources of reactive species with promising industrial and biomedical applications, but an understanding of underlying surface mechanisms is lacking. A kHz-powered surface microdischarge (SMD) operating with N2/O2 mixtures was used to study the biological deactivation of two immune-stimulating biomolecules: lipopolysaccharide (LPS) and peptidoglycan (PGN), found in bacteria such as Escherichia coli and Staphylococcus aureus, respectively. Model polymers were also studied to isolate specific functional groups. Changes in the surface chemistry were measured to understand which plasma-generated species and surface modifications are important for biological deactivation. The overall goal of this work is to determine which effects of CAP treatment are generic and which bonds are susceptible to attack. CAP treatment deactivated biomolecules, oxidized surfaces, and introduced surface bound NO3. These effects can be controlled by the N2 fraction in O2 and applied voltage and vary among different target surfaces. The SMD was compared with an Ar/O2/N2-fed kHz-powered atmospheric pressure plasma jet and showed much higher surface modifications and surface chemistry tunability compared to the jet. Possible mechanisms are discussed and findings are compared with recent computational investigations. Our results demonstrate the importance of long-lived plasma-generated species and advance an atomistic understanding of CAP-surface interactions.

Three distinct modes in a surface micro-discharge in atmospheric pressure He + N2 mixtures

A surface micro-discharge in atmospheric pressure He + N2 mixtures is studied in this paper with an emphasis on the discharge modes. With the N2 admixture increasing from 0.1% to 20%, the discharge evolves from a spatially diffuse mode to a filamentary mode during positive half-cycles of the applied voltage. However during the negative half-cycles, an additional patterned mode emerges between the diffuse and the filamentary modes, which has not been reported before to exist in surface micro-discharges. In the diffuse and patterned modes, the plasmas cover almost the entirety of the mesh area during one cycle after plasma ignition in all mesh elements, and the discharge power increases linearly with the applied voltage. In contrast, plasma coverage of the mesh area is only partial in the filamentary mode and the plasma is more unstable with the discharge power increasing exponentially with the applied voltage. As the surface micro-discharge evolves through the three modes, the density of excited species changes significantly, for instance, the density of N2+(B) drops by ∼20-fold from [N2] = 0.2% to 20%. The N2+(B) is predicted to be generated mainly through successive processes of Penning ionization by helium metastables and electron-impact excitation of N2+(X), the latter is most responsible for the density decrease of N2+(B) because much more N2+(X) is converted to N4+(X) as the increase of N2 fraction. Also, the electron density and electron temperature decrease with the discharge mode transition.

Modeling of simultaneous competitive mixed gas permeation and CO2 induced plasticization in glassy polymers

Plasticization behavior of polymeric membranes, in presence of a second component in the feed is different from plasticization of pure CO2 due to competitive sorption. This study focused on a mathematical model derived for permeation of mixed gases in glassy polymers considering the plasticization case. It was assumed that diffusion coefficient for all components were exclusively a function of plasticizing component. In this study, the partial immobilization model was employed to determine fraction of mobile sorbed gases. This model accurately predicted the permeation behavior of CO2 as plasticizer and N2 in presence of plasticization. The model parameters were calculated by fitting experimental data from literature. Plasticization parameter (β) decreased for both CO2 and N2 by increasing fraction of N2 in the feed. It means that plasticization of glassy polymers was suppressed. This decrease was caused by competitive sorption between CO2 and N2. Indeed N2 in the feed acts as an anti-plasticizer. In addition, permeances of the feed gas components were declined in comparison to pure gases, which might be attributed to reduction of sorption and occupying Langmuir sites with the second component. The proposed model is capable of giving a useful tool to enhance our knowledge related to permeability and selectivity behavior of mixed gas systems in glassy polymeric membranes.

Estimation of CO2–brine interfacial tension using an artificial neural network

Experimental determination of CO2–brine interfacial tension (IFT) usually requires expensive apparatus and sophisticated interpretation procedure and is time-consuming. Hence, it is of practical importance to develop an accurate and reliable model for determining the CO2–brine IFT. This paper presents the use of feed forward artificial neural network (ANN) to accurately estimate CO2–brine IFT based on a database acquired from previous literature. The database consists of a total of 1716 CO2–brine IFT datasets that cover relatively large ranges of pressure (0.1–60.05MPa), temperature (5.25–175°C), total salinity (0–5molkg−1) and mole fractions (0–80%) of impure components. Six independent variables were considered to develop the IFT estimation model: pressure, temperature, monovalent cation (Na+ and K+) molality, bivalent cation (Ca2+ and Mg2+) molality in brine, and mole fractions of N2 and CH4 in injected CO2 streams. The ANN topology was optimized by trial-and-error in order to enhance its capability of generalization and the optimal one was determined to be 6-10-20-1 (10 and 20 neurons in the first and second hidden layers, respectively). The accuracy of the proposed ANN model was highlighted by four evaluation matrices, namely mean absolute error (MAE), mean absolute relative error (MARE), mean squared error (MSE), and determination coefficient (R2) between the measured and estimated IFT. The ANN model was further compared against four empirical IFT correlations developed in previous studies. It was observed that the ANN model outperforms significantly the empirical correlations and provides the most accurate IFT reproduction with respect to pure CO2–pure water, pure CO2–brine and impure CO2 systems.

RF discharge for in situ mirror surface recovery in ITER

Almost all optical diagnostic systems in ITER will require the implementation of mirror recovery and protection systems. Plasma cleaning is considered to be the most promising technique for the removal of metal deposits from optical surfaces. The engineering and physical aspects of RF discharge application for continuous or periodic plasma treatment are discussed with a focus on implementation under ITER conditions. The ion flux parameters obtained in capacitively coupled (CC) RF discharge were measured in the mock-up of a plasma cleaning system. The uniformity of sputtering in CC RF discharge with and without a magnetic field was studied experimentally for the cylindrical discharge reactor geometry and compared with numerical simulations. The sharp increase in the sputtering rate resulting from the non-uniform radial distribution of the ion flux was observed near the electrode edges. The longitudinal magnetic field improves sputtering uniformity. It was demonstrated that Al/Al2O3 deposits can be removed in the Ne and D2 plasma of CC RF discharge but long-term exposition results in the degradation of the polycrystalline molybdenum mirror surface. The efficiency of Al sputtering in the atmosphere containing O2 and N2 fractions was studied in the D2/O2 and D2/N2 plasma of glow discharge. The addition of 2% of oxygen or nitrogen increases the sputtering yield by 3–4 times as compared with that in a nominally pure D2 discharge. The impact of metal deposits on the performance of diagnostic mirrors is discussed. It was shown that an ultrathin metallic film with a thickness as low as a few nm may cause a significant degradation of diagnostic mirrors with a transparent coating.

Mesopore modification of beta zeolites by sequential alkali and acid treatments: Narrowing mesopore size distribution featuring unimodality and mesoporous texture properties estimated upon a mesoporous volumetric model

For mesopore modification of zeolite beta prepared in protonic form (H-Beta, Si/Al = ca.18.7) to concentrate pore size distributions, the framework T-atoms of H-Beta crystals were extracted according to the sequential schemes: hydrothermal pre-etching using incipiently wetted alkaline solutions, bulk alkaline treatment, and acid leaching coupling with ammonium exchange. Based on XRD, FTIR, N2 adsorption at 77 K, SEM, TEM, EDX, ICP–AES, and immersion porosimetry, structure properties of the hierarchical materials obtained were correlated with the sequential treatment processes. In contrast to single bulk alkaline treatment, the hydrothermal alkali pre-etching enables to impair or eliminate broadly secondary pore–distributed peaks, the bulk alkaline treatment before acid leaching facilitates textural mesopore formation, and the final acid leaching plus ammonium exchange leads to moderate increases in mesoporosity and mesopore diameters, and also to a suitable enhancement of Si/Al ratios. FTIR spectra provided evidence for the short range ordering of modified zeolites and for the presence of zeolitic ring sub-units in the basic filtrate. However, the microporosity, crystallinity and yield relative to the parent are reduced by increased alkaline concentrations. A novel model was built for estimating a volumetric fraction of intracrystalline-to N2 adsorbed mesopores. Calculation results show that this volumetric fractional model promises to identify the mesoporous textural property, explaining how many volumetric fractions of mesopores are to locate in beta crystallite entities. In addition, the hierarchical beta possesses a mesopore network with higher hydrothermal stability at 873 K.

Measurement of the vapour–liquid equilibrium of binary and ternary mixtures of CO2, N2 and H2, systems which are of relevance to CCS technology

The p–T phase envelopes of four binary and two ternary mixtures of carbon dioxide (CO2), nitrogen (N2) and hydrogen (H2) have been reported at temperatures between 252 and 304K. The compositions of the binary mixtures are xN2=0.0201 and 0.0399 for CO2+N2 and xH2=0.0300 and 0.0499 for CO2+H2, respectively. For the two ternary mixtures of CO2+N2+H2, the compositions are xN2=0.020, xH2=0.030 and xN2=0.040, xH2=0.030. The experimental data show that the bubble-point pressures of the CO2-permanent gas mixtures increase substantially when adding only several percent (mole fraction) of N2, H2 or both in CO2. H2 has the largest effect on the bubble-point pressure. For a mixture with 5% H2 in CO2, the bubble-point pressure reaches 10.1MPa at 288.15K, corresponding to an increase of 99% from the vapour pressure of pure CO2. These vapour–liquid-equilibrium data have also been compared to those predicted using the GERG-2004 and Peng–Robinson (PR) equations of state. Between the two models, the PR equation of state gives the smaller deviations (2.5–4.2%) for the bubble-point lines of CO2+H2 when using temperature-dependent binary interaction parameters, while both models show excellent agreement (0.4–2.8%) between the experimental and predicted data for CO2+N2. We also successfully model the CO2+H2 data using molecular simulation.

Using the same cut-off for sulfur hexafluoride and nitrogen multiple-breath washout may not be appropriate.

Recent evidence suggests that results from multiple-breath washout (MBW) using nitrogen (N 2 ) as washout gas are different to those obtained by using sulfur hexafluoride (SF 6 ). Explanations were mainly related to different MBW equipment and gas properties. We aim to mention a new aspect, namely using the same cut-off in both techniques to determine lung clearance index (usually 2.5% of initial tracer concentration) irrespective of additional contribution of tissue-nitrogen in N 2 -MBW. In a simple model calculation we subtracted 1% tissue-N 2 from the N 2 -MBW in real washout traces from two children, one with cystic fibrosis (CF) and one healthy. This "SF 6 -washout simulation" decreased LCI differently in the children. In the healthy subject 1/40 th (2.5%) was achieved two breaths earlier compared to the original signal and changed LCI from 6.7 to 5.9 (12%), while in CF 1/40 th was achieved 19 breaths earlier leading to a LCI decrease from 13.7 to 10.0 (27%). It would have been required to wash out SF6 until 1/66 th (1.5%) to be comparable to N 2 washout at 1/40th (2.5%), or to stop N2-MBW already at 3.5% of the starting concentration to make both techniques comparable. We show that a basic physiological-mathematical difference between both techniques additionally accounts for different sensitivities and poor agreement between SF 6 - and N 2 -MBW. The best way of adjusting for the contribution of tissue-N 2 needs to be examined in future studies. Thus, despite increasing use in different disease groups, the books on MBW technology are obviously not closed yet.

Local Dynamics of Chemical Kinetics at Different Phases of Nitriding Process

The local dynamics of chemical kinetics at different phases of the nitriding process have been studied. The calculations are performed under the conditions where the temperature and composition data are provided experimentally from an in-service furnace. Results are presented in temporal variations of gas concentrations and the nitrogen coverage on the surface. It is shown that if it is available in the furnace, the adsorption of the N2 gas can seemingly start at temperatures as low as 200 °C. However, at such low temperatures, as the diffusion into the material is very unlikely, this results in the surface poisoning. It becomes clear that, contrary to common knowledge, the nitriding heat treatment with ammonia as a nitrogen-providing medium is possible at temperatures like 400 °C. Under these conditions, however, the presence of excess amounts of product gas N2 in the furnace atmosphere suppresses the forward kinetics in the nitriding process. It seems that the best operating point in the nitriding heat treatment is achieved with a mixture of 6% N2. When the major nitriding species NH3 is substituted by N2 and the N2 fraction increases above 30%, the rate of the forward reaction decreases drastically, so that there is no point to continue the furnace operation any further. Hence, during the initial heating phase, the N2 gas must be purged from the furnace to keep its fraction less than 30% before the furnace reaches the temperature where the reaction starts.

Influence of mixture compositions on ion energy distributions in Ar/N2 electron cyclotron resonance plasma

In this report, the mass and energy spectra of ions in Ar/N2 electron cyclotron resonance (ECR) plasma at the microwave power of 100 W and the gas pressure of 1 Pa are investigated by a Hiden EQP analyzer, and also the plasma optical emission spectra are recorded by optical emission spectroscopy (OES). Singly charged Ar+ and N2+ as the dominant ions are detected. The ion energy distribution functions (IEDFs) of Ar+ and N2+ exhibit complicated evolutions of peak structures with varying the N2 fractions. The IEDF of Ar+ is bimodal at the low N2 fractions, and changes to trimodal structure as the N2 fractions are near 40%. However, it turns to be unimodal at the N2 fractions above 80%. The IEDFs of N2+ present unimodal structures in the case of both high and low N2 fractions, and the bimodal profiles appear as the N2 fractions are around 50%. It is suggested that the distributed ionization and the charge–exchange reactions between ions and neutrals are responsible for the evolutions of peak structures for IEDFs.

CO2 Conversion in a Microwave Plasma Reactor in the Presence of N2: Elucidating the Role of Vibrational Levels

A chemical kinetics model is developed for a CO2/N2 microwave plasma, focusing especially on the vibrational levels of both CO2 and N2. The model is used to calculate the CO2 and N2 conversion as well as the energy efficiency of CO2 conversion for different power densities and for N2 fractions in the CO2/N2 gas mixture ranging from 0 to 90%. The calculation results are compared with measurements, and agreements within 23% and 33% are generally found for the CO2 conversion and N2 conversion, respectively. To explain the observed trends, the destruction and formation processes of both CO2 and N2 are analyzed, as well as the vibrational distribution functions of both CO2 and N2. The results indicate that N2 contributes in populating the lower asymmetric levels of CO2, leading to a higher absolute CO2 conversion upon increasing N2 fraction. However, the effective CO2 conversion drops because there is less CO2 initially present in the gas mixture; thus, the energy efficiency also drops with rising N2 fraction.

Laser diagnostics of pulverized coal combustion in O2/N2 and O2/CO2 conditions: velocity and scalar field measurements

Optical diagnostic techniques are applied to a 21 kW laboratory-scale pulverized coal–methane burner to map the reaction zone during combustion, in mixtures with varying fractions of O2, N2 and CO2. Simultaneous Mie scatter and OH planar laser-induced fluorescence (PLIF) measurements have been carried out to study the effect of the oxidizer/diluent concentrations as well as the coal-loading rate. The spatial distribution of soot is captured using laser-induced incandescence (LII). Additionally, velocity profiles at selected axial locations are measured using the pairwise two-dimensional laser Doppler velocimetry technique. The OH PLIF images capture the reaction zones of pilot methane–air flames and the variation of the coal flame structure under various O2/CO2 compositions. Coal particles devolatilize immediately upon crossing the flame interface, so that the Mie scatter signal almost vanishes. Increasing coal-loading rates leads to higher reaction rates and shorter flames. LII measurements show that soot is formed primarily in the wake of remaining coal particles in the product regions. Finally, differences in the mean and RMS velocity field are explained by the combined action of thermal expansion and the changes in particle diameter between reacting and non-reacting flows.

Fast carbon nanofiber growth on the surface of activated carbon by microwave irradiation: A modified nano-adsorbent for deep desulfurization of liquid fuels

Carbon nanofibers were fabricated on the surface of regular activated carbon (AC) by microwave-assisted chemical vapor deposition (CVD) method. Methane and ethane were comparatively used as the source gases to figure out the textural and particulate properties and efficiency of the produced nano-adsorbents in sulfur adsorption from a fuel model. AC granules were firstly impregnated with nickel and exposed to a flow of hydrocarbon–nitrogen mixture through a stationary bed. A 900W household microwave apparatus was used as the energy source to decompose the hydrocarbon and grow up nanofibers on the surface. Effect of catalyst fraction, radiation time and inlet gas flow rate were studied as the influential synthesis parameters. The 0.5wt% Ni-impregnated AC was exposed to equal mole fraction of N2–hydrocarbon mixture with WHSV of 6.7ml/gmin and the result revealed the highest yield of nanofibers growth on the surface. The diameter of nanofibers made from ethane was almost twofold over the diameter of nanofibers made from methane. Thiophene and dibenzothiophene removal were comparatively investigated by a series of batch adsorption experiments with a model fuel comprising n-octane. The sulfur removal efficiency was improved up to 87% compared with the original AC. During two hours contact time, the sulfur content of solution was decreased from 290 to 45ppm by the modified AC surface.