Oxidation Of N-decane Research Articles

Photocatalytic oxidation of n-decane in a NETmix photoreactor: Insights into the reactor geometry and illumination mechanism

This study focuses on the gas-phase photocatalytic degradation of n-decane using a NETmix photoreactor illuminated by UVA light-emitting diodes. The photoreactor is a static mixer composed of a network of cylindrical chambers interconnected by prismatic channels imprinted in a stainless-steel slab sealed with a borosilicate glass slab (reactor window with 55.7 cm2 of illuminated area). Photocatalytic performance was evaluated as a function of the flow rate (0.67 to 15 L min−1), corresponding to Reynolds number (Re) from 54 to 1209, using NETmix plates with 1 mm (92.3 cm2) and 3 mm depth (165.4 cm2), under back-side (BSI) and front-side (FSI) illumination mechanisms. The TiO2-P25 loading over the borosilicate slab (25–100 mg; BSI optimal: 75 mg) and stainless-steel slabs (100–400 mg; FSI-1/FSI-3 optimal: 200/400 mg) was optimized. Within system constraints, higher Re corresponds to increased reaction rate, apparent quantum yield, and reactivity, with decreased degradation efficiency, due to a reduction in the residence time, regardless of the reactor geometry and illumination. Moreover, operating at the same Re, the NETmix plate with 3 mm depth achieves reaction rates 2.2-/1.9-fold higher than 1 mm, considering FSI/BSI mechanisms. The results were consistent with applied experimental conditions and ray tracing simulations, indicating superior kinetic performance with higher catalyst superficial area. Ray tracing was coupled with Computational Fluid Dynamics (CFD) simulations to evaluate n-decane single-pass oxidation. A 94 % n-decane maximum experimental conversion was attained for a Re of 54, representing an error of ∼ 6.6 % compared to CFD simulation. In these conditions, only 1 % of n-decane was not mineralized, being identified aldehydes, alkanes, carboxylic acids, and ketones as the main reaction by-products. The influence of relative humidity (2 %-40 %) and n-decane inlet concentration (15–114 ppm) were also investigated.

A theoretical calculation and kinetic modeling analysis of H-abstraction from 1-octene for subsequent isomerization and [formula omitted]-dissociation

As a main component of alkenes, 1-octene is the key important intermediate in the process of oxidation or pyrolysis of n-decane or higher alkanes. In this work, quantum chemistry calculations of the 1-octene combustion and pyrolysis were illustrated for the potential energy surface, including the H-abstraction reactions and subsequent isomerization and β-dissociation reactions. The primary β-dissociation reactions after the H-abstraction reaction involving H atoms and CH3/NH2/NO2 radicals are detailed description with kinetic calculation. The rate constants of the primary pyrolysis reaction of 1-octene from 300 to 2000K were determined with the RRKM theory combined with CTST. The results indicated the H-abstraction reactions adhere to the Evans-Polanyi principle within the calculation uncertainty 1 kcal/mol. The 3-site exhibited the highest competitiveness in the 1-octene H-abstraction process and dominated, whereas the 1-site is lack of competitiveness due to overcome higher energy barriers (2–4 kcal/mol). The five-membered or six-membered ring in the H atom transfer process served as the most favorable structure for the isomerization reaction of 1-octenyl because of the lowest transition state energy. The dissociation channel for converting 1-octenyl to various octadienes and H atoms consumed the least 1-octenyl in the dissociation process. Following temperatures exceeding 570K, INT6 exhibits a preeminent 1-octenyl consumption ratio, attributed to the synergy between the enthalpy and entropy effects. The modified kinetic data of 1-octene H-abstraction reactions by four radicals and the subsequent isomerization and β-dissociation was expanded from 300 to 2000K, 0.01–100 atm. The modified model shows the better experimental prediction capabilities.

Low-temperature oxidation of n-octane and n-decane in shock tubes: Differences in time histories of key intermediates

The impact of chain length on the time histories of key intermediate species that form upon first-stage ignition was studied experimentally in a shock tube using multi-color laser absorption diagnostics. CO, CH2O, OH, and composite time histories of heavier carbonyls were measured simultaneously during the low temperature oxidation of n-octane & n-decane in the temperature range of 720–860 K, and pressure range of 4.1–5.8 atm. The test mixtures were 0.64% & 0.6% fuel in oxygen, respectively. A two-color diagnostic was also developed and used in tandem with other diagnostics to quantify the evolution of temperature during oxidation. To our knowledge, this work reports the first measurement of CH2O, OH, and temperature during oxidation of C8 or heavier hydrocarbon fuels at low temperatures. The measured time histories were also compared against the predictions of two recent detailed kinetic models. Significant differences in the measured and predicted first-stage ignition delay times, absolute concentration of species post-ignition and the maximum rate of formation of species were observed. Our measurements will serve as targets for further refinement of these detailed kinetic models and in the development of rate rules for similar classes of fuels. The measurements also revealed significant differences in the relative reactivity of n-octane and n-decane. Taken together with previous speciation studies conducted in n-heptane, we observe a strong correlation between the species time histories, reactivity, and chain length of straight chain alkanes. This observation lends further support to the selection of CO and CH2O as target species for development of Low-Temperature Hybrid Chemistry (HyChem) models for real transportation and aviation fuels in future.

Catalytic Oxidation of n-Decane, n-Hexane, and Propane over Pt/CeO2 Catalysts.

Pt species with different chemical states and structures were supported on CeO2 by solution reduction (Pt/CeO2-SR) and wet impregnation (Pt/CeO2-WI) and investigated in catalytic oxidation of n-decane (C10H22), n-hexane (C6H14), and propane (C3H8). Characterization by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, H2-temperature programming reduction, and oxygen temperature-programmed desorption showed that Pt0 and Pt2+ existed on Pt nanoparticles of the Pt/CeO2-SR sample, which promoted redox, oxygen adsorption, and activation. On Pt/CeO2-WI, Pt species were highly dispersed on CeO2 as the Pt-O-Ce structure, in which surface oxygen decreased significantly. The Pt/CeO2-SR catalyst presents high activity in oxidation of C10H22 with a rate of 0.164 μmol min-1 m-2 at 150 °C. The rate increased with oxygen concentration. Moreover, Pt/CeO2-SR presents high stability on feed stream containing 1000 ppm C10H22 at gas hour space velocity = 30,000 h-1 as low as 150 °C for 1800 min. The low activity and stability of Pt/CeO2-WI were probably related to its low availability of surface oxygen. In situ Fourier transform infrared results showed that the adsorption of alkane occurred through the interaction with Ce-OH. The adsorption of C6H14 and C3H8 was much weaker than that of C10H22, which resulted in the decrease in activity for C6H14 and C3H8 oxidation of Pt/CeO2 catalysts.

Impacts of Nano-Sized Co3O4 on Ignition and Oxidation Performance of N-Decane and N-Decane/1,2,4-Trimethylbenzene Mixtures

ABSTRACT Nano-sized Co3O4 is an effective catalyst for fuel oxidation due to its high capacity of oxygen storage, and it is thus frequently applied in improving the oxidation performance of hydrocarbon fuels. In our present work, attempts were made to study the catalytic performance of Co3O4 for the oxidation of liquid fuels over a wide temperature range. Neat n-decane and n-decane/1,2,4-trimethylbenzene mixtures were chosen because they are typical liquid hydrocarbon fuels. The evidences from this study suggest that the temperatures of both fuel ignition and full conversion are significantly decreased by Co3O4 catalyst. CO2 is the only product detected in the catalytic oxidation, which also proves the complete oxidation of the liquid fuels. Furthermore, to explore the possible reaction pathways on the catalyst surface, temperature-dependent and time-dependent in situ DRIFTS were employed to identify surface species and analyze catalytic mechanism. Various surface intermediates including bidentate, monodentate carbonate species, carboxylate species and molecular adsorbed n-decane have been observed. The experimental results indicate that n-decane oxidation over Co3O4 proceeds via the Mars-van Krevelen mechanism where lattice oxygen plays a critical role in the fuel oxidation.

CFD and radiation field modeling of the NETmix milli-photocatalytic reactor for n-decane oxidation at gas phase: Effect of LEDs number and arrangement

This work describes the modeling of the NETmix milli-photocatalytic reactor for n-decane oxidation at gas phase coupling non-sequential ray tracing with computational fluid dynamics (CFD). The walls of the NETmix network, comprising cylindrical chambers interconnected by prismatic channels, were coated with a thin-film of TiO2-P25. The reactor was sealed with a UVA transparent borosilicate glass slab (reactor window). The illumination system, located above the reactor window, consists of a LED plate. A total of 28 variations in the illumination system were analyzed, considering 5, 12, 18 or 30 high power UVA LEDs arranged in a staggered configuration or of 6, 15 or 28 inline LEDs. The distance between the LEDs and the reactor window was varied between 6 mm and 48 mm. The radiation field over the catalyst surface provided by each illumination system was obtained through ray tracing simulations. The registered irradiance levels, light absorption efficiency, homogeneity of the field and overall photonic efficiency were analyzed for all the 28 simulated cases. The irradiance levels registered varied between 57 W/m2 and 589 W/m2, with a light absorption efficiency up to 44%. The impact of the illumination systems on n-decane oxidation was evaluated through CFD simulations. Results allowed to appoint an ideal LEDs-to-reactor distance, that balances the irradiation levels with the radiation field uniformity, as well as an ideal system able to achieve high pollutant degradation with low power demand.

Formation of PAHs, phenol, benzofuran, and dibenzofuran in a flow reactor from the oxidation of ethylene, toluene, and n-decane

The necessity to reveal the formation mechanism of not only polycyclic aromatic hydrocarbons (PAHs) but also oxygenated PAHs (OPAHs) during combustion is increasing. Although many studies on PAHs have been conducted, fundamental studies investigating OPAH formation are still limited. Phenol, benzofuran, and dibenzofuran were selected as OPAHs in this study. We experimentally investigated fuel-rich oxidation in a flow reactor at atmospheric pressure, mean gas temperatures from 1050 to 1350 K, residence times from 0.2 to 1.5 s, and equivalence ratios from 3.0 to 12.0. Ethylene, toluene, and n-decane were used as fuels. Three kinds of OPAHs as well as 23 kinds of PAHs including monocyclic structures were quantitatively measured through a direct sampling using gas chromatography mass spectrometry. The results showed that concentrations of PAHs and OPAHs were strongly affected by the fuel type, with increasing concentrations in the following order: ethylene < n-decane < toluene. A chemical kinetic model for OPAH formation was developed based on a recent PAH growth model. The model showed that the predicted concentrations of OPAHs and PAHs were in reasonable agreement with the measured data in this study. Some modifications were made to the previous model based on recent literature studies and on the comparison of the simulated and measured results. The effect of the fuel type on the formation of PAHs and OPAHs was investigated through kinetic analysis using the model to discuss their reaction pathways.

Cfd and Radiation Field Modeling of the Netmix Milli-Photocatalytic Reactor For N-Decane Oxidation at Gas Phase: Effect of Leds Number and Arrangement

Cfd and Radiation Field Modeling of the Netmix Milli-Photocatalytic Reactor For N-Decane Oxidation at Gas Phase: Effect of Leds Number and Arrangement

Diffusion combustion of n-decane with unpassivated aluminum nanoparticles additives: Аnalysis of mechanism and numerical simulation

Possible mechanisms of the increase in the flame front temperature, observed in experiments with diffusion combustion of n-decane with the addition of unoxidized aluminum nanoparticles with a diameter of 20 nm, were analyzed numerically. It was shown that at nanoparticle concentrations of 0.5 and 2.5 wt%, which were considered in the experiment, the heat release caused by the oxidation of aluminum can induce only a slight (up to 10 K) increase in the temperature of the front. Numerical modeling of a laminar diffusion flame allowed us to establish that the most probable cause of an increase in the temperature of the flame front is the acceleration of gas-phase reactions of n-decane oxidation. A detailed kinetic mechanism of ignition and oxidation of n-decane in the presence of aluminum vapor was developed to test the previously proposed hypothesis of promoting the n-decane combustion with aluminum vapor. Numerical calculations using the developed kinetic mechanism have shown that gaseous aluminum as a combustion promoter does not allow achieving the same increase in the flame front temperature as in the experiment. It makes the development of alternative mechanisms for promoting the combustion of n-decane by aluminum nanoparticles urgent.

N-Decane Reforming by Gliding Arc Plasma in Air and Nitrogen

Plasma cracking of n-decane is carried out in a new type of gliding arc flow reactor in the atmosphere of nitrogen and air, at a flow range of 25–45 L/min with an interval of 5 L/min. The relationship between arc evolution and discharge voltage and current signals is established by synchronous recording with high-speed camera and oscilloscope. It is recorded that the rotating frequency of the gliding arc is in the range of 81–176 Hz, which increases with the rise of the flow rate and has no direct relationship with the type of gas. When air is used as the discharge medium, although the luminous intensity of the arc is weak, arc rotation is relatively stable, and the specific input energy is higher, which is 58% higher than that of nitrogen. In addition, the partial oxidation of n-decane provides extra heat for cracking, which is helpful to improve the efficiency of plasma cracking. The cracking products mainly include hydrogen, ethylene, acetylene, methane, propylene and ethane. The concentration of each component is higher, reaching the maximum value at the flow rate of 40 L/min, with the hydrogen selectivity of 23.1%. However, when nitrogen plasma is selected, the kinds of products are reduced, containing only hydrogen, ethylene and acetylene, and the concentrations are lower than 0.5%. Two parameters, energy conversion efficiency and carbon based characterization effective cracking rate, were proposed to evaluate the cracking effect of flow reactor.

Ozonation and ozone-enhanced photocatalysis for VOC removal from air streams: Process optimization, synergy and mechanism assessment

The present work evaluates ozone driven processes (O3, O3/UVC, O3/TiO2/UVA) in the NETmix mili-photoreactor, as a cost-effective alternative for the removal of volatile organic compounds (VOCs) from air streams, using n-decane as a model pollutant. The network of channels and chambers of the mili-photoreactor was coated with a TiO2-P25 thin film, resulting in a catalyst coated surface per reactor volume of 990 m2 m−3. Ozone and n-decane streams were fed to alternate chambers of the mili-photoreactor, promoting a good contact between O3/n-decane/catalyst. Initially, direct reaction between n-decane and ozone (ozonation) was assessed for different O3/n-decane (O3/dec) feed molar ratios and total feed flow rates. Under the best conditions, ozonation process achieved total n-decane conversion (below the limit of detection), yielding a reaction rate (rdec) of 6.8 μmol min−1 or 6.7 mmol m−3reactor s−1. However, the low reactivity of ozone with the degradation by-products resulted in a quite poor mineralization (~10%). For the O3/UVC system, an increase on relative humidity from 7 to 40% slight improved the n-decane oxidation rate, mainly associated with the generation of HO from the reaction of active oxygen radicals (O) and water molecules. A strong synergistic effect was observed when coupling TiO2/UVA photocatalysis with ozonation (O3/TiO2/UVA), enhancing substantially the mineralization of n-decane molecules up to 100% under O3/dec feed molar ratio of 15, photonic flux of 2.67 ± 0.03 J s−1 and a residence time of 2.0 s. Different reaction intermediates were detected for O3, TiO2/UVA and O3/TiO2/UVA oxidative systems, indicating the participation of different oxidant species (O3, HO, O, etc.).

Effect of catalyst coated surface, illumination mechanism and light source in heterogeneous TiO2 photocatalysis using a mili-photoreactor for n-decane oxidation at gas phase

This work evaluates the effect of the catalyst coated surface per reactor volume, illumination mechanism (back side (BSI) or front side (FSI) illumination) and light source on heterogeneous TiO2 photocatalysis using a mili-photoreactor, for the oxidation of a volatile organic compound in a gas stream. A thin film of TiO2-P25 was uniformly deposited on the front borosilicate window of the mili-photoreactor (BSI mechanism) or on the network of channels and chambers imprinted in the back stainless steel slab (FSI mechanism) using a spray system. BSI and FSI mechanisms were assessed using two different UVA LED systems (9 LEDs – LED9 and 18 LEDs – LED18), UVA lamps and simulated solar light as radiation sources. Under BSI and solar light the maximum reaction rate (rdec) obtained was 1.0 µmol min−1, whereas a 1.7-fold increase was attained using BSI-LED9. Although under FSI mechanism the catalyst coated surface per reactor volume is three times higher than under BSI, the maximum rdec for FSI showed only a 1.4 and 1.1-fold increase using simulated solar light and LED9, respectively, when compared with BSI. In order to provide a better light distribution over the catalyst coated surface, a new LED plate with 18 LEDs was designed and tested. Under FSI or BSI mechanisms and using the LED18 system, a ∼3.6 fold increase on the maximum rdec was observed when compared to the LED9 system. However, even for the LED18 system, similar maximum reaction rates are observed for BSI and FSI mechanisms. This means, that regardless of the light source configuration used, ∼60% of the catalyst coated surface is not illuminated.

Hydroperoxide Measurements During Low-Temperature Gas-Phase Oxidation of n-Heptane and n-Decane

A wide range of hydroperoxides (C1-C3 alkyl hydroperoxides, C3-C7 alkenyl hydroperoxides, C7 ketohydroperoxides, and hydrogen peroxide (H2O2)), as well as ketene and diones, have been quantified during the gas-phase oxidation of n-heptane. Some of these species, as well as C10 alkenyl hydroperoxides and ketohydroperoxides, were also measured during the oxidation of n-decane. These experiments were performed using an atmospheric-pressure jet-stirred reactor at temperatures from 500 to 1100 K and one of three analytical methods, time-of-flight mass spectrometry combined with tunable synchrotron photoionization with a molecular beam sampling: time-of-flight mass spectrometry combined with laser photoionization with a capillary tube sampling, continuous wave cavity ring-down spectroscopy with sonic probe sampling. The experimental temperature at which the maximum mole fraction is observed increases significantly for alkyl hydroperoxides, alkenyl hydroperoxides, and then more so again for hydrogen peroxide, compared to ketohydroperoxides. The influence of the equivalence ratio from 0.25 to 4 on the formation of these peroxides has been studied during n-heptane oxidation. The up-to-date detailed kinetic oxidation models for n-heptane and for n-decane found in the literature have been used to discuss the possible pathways by which these peroxides, ketene, and diones are formed. In general, the model predicts well the reactivity of the two fuels, as well as the formation of major intermediates.

Time-resolved carbon monoxide measurements during the low- to intermediate-temperature oxidation of n-heptane, n-decane, and n-dodecane

Time-resolved mid-infrared laser absorption measurements of carbon monoxide were carried out during the low- and intermediate-temperature oxidation of n-heptane, n-decane, and n-dodecane in a shock tube. Dilute mixtures of n-alkane/O2/Ar were shock heated, initiating oxidation and resulting in CO formation and heat release with time scales of 1 to 10ms. Experiments are reported in two temperature and oxygen concentration ranges, 686–797K at 5% O2 and 1121–1290K at 0.5% O2, for pressures around 10atm. For measurements in the lower temperature range, first-stage ignition was observed and found to exhibit negative-temperature-coefficient behavior. The low-temperature reactivity was found to increase with increasing n-alkane chain length and first-stage ignition delay to be well correlated with literature derived cetane numbers. The time-resolved CO measurements and first-stage ignition delay times provide quantitative targets for kinetic models that are sensitive to important low-temperature ignition chemistry; comparisons are made with n-alkane kinetic models from the literature.

Intensification of heterogeneous TiO2 photocatalysis using an innovative micro-meso-structured-photoreactor for n-decane oxidation at gas phase

The main goal of this work is to overcome barriers in heterogeneous TiO2 photocatalysis application towards indoor air decontamination by process intensification. The photocatalytic oxidation (PCO) of gas-phase n-decane was studied using a micro-meso-structured-photoreactor irradiated by simulated solar light, consisting of chambers and channels mechanically engraved in an acrylic slab. The network of chambers and channels is sealed with a borosilicate slab, allowing a good light penetration through the entire reactor depth. A sheet of cellulose acetate (CA) coated, in one side, with TiO2-P25 was assembled between the two slabs, allowing high spatial illumination homogeneity over the catalyst surface. The P25 thin film was in contact with the air stream flowing in the network. The reactor contains 1.95g of TiO2 in contact with the air stream per liter of reactor volume and the illuminated catalyst surface area, in contact with the gas phase, per reactor volume was calculated to be 349m2m−3, which is ∼1.4 times higher than that obtained for an annular photoreactor packed with CA monolithic structures coated with TiO2-P25. The PCO reaction rate, rdec, was assessed under different experimental conditions: amount of TiO2 supported in CA sheets, n-decane feed concentration, feed flow rate, relative humidity and UV irradiance. The highest rdec value (0.82μmolmin−1) was achieved when the following conditions were employed: mTiO2=75mg, Cdec,feed=1.31×10−2molm−3, Qfeed=220cm3min−1 and I=38.4Wm−2. The maximum reactivity of photocatalyst in combination with the photoreactor was 6.93×10−4molm−3reactor s−1, which is a 21.4 fold increase when compared with the annular photoreactor, highlighting the enhancement of mass and photons transfer.

Evaluation of a solar/UV annular pilot scale reactor for 24 h continuous photocatalytic oxidation of n-decane

A pilot scale single-pass continuous-flow annular photoreactor (rannulus=21.3mm) was designed and manufactured featuring a compound parabolic collector (CPC) to capture both direct and diffuse solar radiation and, simultaneously, artificial UVA lamps, in order to examine the possibility of working continuously day and night. Cheap, lightweight and easily shaped cellulose acetate materials, which are transparent in the TiO2 activation range, were used as supports, as an alternative to classic porous solid monolithic structures. Such configuration allows that only 1% of the reactor volume is filled with photoactive material.The photocatalytic oxidation (PCO) of n-decane (Cdec, feed=10ppm, Qfeed=2Lmin−1, τ=44s) over cellulose acetate monolithic structures coated with different TiO2-based photocatalytic films (Lcatalytic bed=144cm) was studied under solar and artificial UVA radiation. Gas-phase n-decane conversions up to 100% were attained using P25 or PC500 photocatalytic films under solar irradiances starting from 16WUVm−2 in the morning (sunrise, increasing temperature) and down to 3WUVm−2 in the afternoon (sunset, decreasing temperature). An increase of the UV irradiance at total n-decane conversion promotes the formation of CO2. The excess of photons reaching the photocatalytic bed favours the direct reaction pathway of CO2 generation. The PCO of n-decane enhanced 29% resulting in 100% of conversion using PC500 film instead of P25 film, under artificial UVA radiation (I=29Wm−2). Results indicate that combining both radiation sources, a 24h continuous PCO process towards the removal of n-decane can be accomplished.

Gas phase oxidation of n-decane and PCE by photocatalysis using an annular photoreactor packed with a monolithic catalytic bed coated with P25 and PC500

Perchloroethylene (PCE) and n-decane are persistently present in the indoor air of several industrial/corporate facilities and households. The present paper reports studies on the photocatalytic oxidation (PCO) of n-decane and PCE using an annular photoreactor equipped with a compound parabolic collector (CPC) and packed with transparent cellulose acetate monolithic structures coated with two commercially available TiO2, namely PC500 and P25, under simulated solar light. Such configuration allowed the illumination of the whole tubular reactor perimeter and catalytic bed, enhancing therefore the photonic efficiency and to take advantage of the low pressure drop and the high surface-area-to-volume ratio, typical of honeycomb reactors. The influence of the type of TiO2, feed flow rate, pollutant concentration, relative humidity, gas-phase molecular oxygen and irradiance on the pollutants PCO was assessed. PC500 film showed higher conversion of both pollutants in comparison with P25 despite the lower mass of catalyst used for film coating. n-Decane (Cdec,feed=71ppm) and PCE (CPCE,feed=1095ppm) conversions close to 100% were obtained operating at Qfeed=150cm3min−1 (τ=88s), I=38.4WUVm−2 and RH=40%. The mineralization's of PCE over both photocatalytic films were similar. However, n-decane was 100% and 69% mineralized respectively over PC500 and P25 films, under the same operating conditions. In addition, competitive adsorption between the pollutants and water molecules on the TiO2 film surface was observed above 20% of RH. Results obtained at low RH suggest that Cl radical chain propagation reactions may be included in the PCO mechanism of PCE. Finally, the absence of oxygen drastically impairs the photoreaction.

High-pressure reduced-kinetics mechanism for n-hexadecane autoignition and oxidation at constant pressure

In previous work, a local full self similarity (LFS2) was identified between (properly) normalized thermo-kinetic quantities when plotted against a normalized temperature. The local partial self similarity (LPS2), which is the computationally efficient companion of LFS2, was coupled with a simple tabulation scheme and yielded highly-accurate twenty-light-species reduced mechanisms for constant-mass and constant-volume autoignition and oxidation of n-heptane, n-decane, n-dodecane and iso-octane. The LFS2 and LPS2 reduction framework coupled with tabulation were combined into a method here called Local Self Similarity Tabulation (LS2T). The LS2T method is here extended and validated for constructing reduced kinetics mechanisms for the constant-mass autoignition and oxidation of an even heavier hydrocarbon, n-hexadecane, but now at constant pressure conditions for a wide range of initial conditions. The method employs the same twenty light species as species progress variables as in the lighter alkanes previously studied, and tabulates through the LPS2 all information involving any heavy species. The template mechanism used for reduction is the detailed 2115-species kinetics from the Lawrence Livermore National Laboratory. Results are presented for the n-hexadecane autoignition and oxidation at the high pressures encountered during engine operation and for several initial temperatures and equivalence ratios. We show that the utilization of a real-gas equation of state (the Peng–Robinson equation of state with a volume correction) is essential in obtaining accurate results. Reduced-kinetics plots of the temperature and the major species, including the OH temporal evolution, computed with the LS2T method accurately duplicated those obtained with the LLNL detailed mechanism.

Experimental and kinetic modeling study of pyrolysis and oxidation of n-decane

The pyrolysis of n-decane was investigated in a flow reactor at 5, 30, 150 and 760Torr, and the oxidation of n-decane at equivalence ratios of 0.7, 1.0 and 1.8 was studied in laminar premixed flames at 30Torr. In both experiments, synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS) was used to identify combustion species and measure their mole fraction profiles. A new detailed kinetic model of n-decane with 234 species and 1452 reactions was developed for applications in intermediate and high temperature regions, and was validated against the experimental results in the present work. The model was also validated against previous experimental data on n-decane combustion, including species profiles in pyrolysis and oxidation in high pressure shock tube and atmospheric pressure flow reactor, jet stirred reactor oxidation, atmospheric pressure laminar premixed flame, counterflow diffusion flame and global combustion parameters such as laminar flame speeds and ignition delay times. In general, the performance of the present model in reproducing these experimental data is reasonably good. Sensitivity analysis and rate of production analysis were conducted to understand the decomposition processes of n-decane.

Oxidation kinetics of n-decane in the presence of an inhibiting composition: A mathematical model

We designed an algorithm and software for inverse kinetic problem solving by conditional global minimization of the deviation of calculated data from experimental data. This approach allows use of more complete information on the process, which narrows the region of feasibility and increases the quality of mathematical simulation of chemical reactions. The algorithms designed were tested in the kinetic description of a complex liquid-phase chain reaction, specifically, the oxidation of n-decane in the presence of an inhibiting composition, viz., para-oxydiphenylamine + n-decanol.