Kinetic Reaction Mechanism Research Articles

Reusable CuFe2O4–Fe2O3 catalyst synthesis and application for the heterogeneous photo-Fenton degradation of methylene blue in visible light

Abstract Mixed iron and copper oxides were synthesized by the modified Pechini method. Calcined (at different temperatures), characterized and used for the removal of methylene blue dye (MB) by solar photocatalysis. The materials exhibited magnetic behavior and low values of surface area (0.1 to 42.2 m2. g−1). According to the diffuse reflectance spectra, the prohibited band intervals of the samples ranged from 1.92 to 2.4 eV. The results of the X-ray diffraction analysis showed that the hematite and copper ferrite phases were the main responsible for the high efficiency of the photochemical reaction, with apparent kinetic constant equal to k =0.016 min−1 and 100% removal of the dye in 180 min of reaction (starting from an initial solution with 50 mg.L−1 of the dye). MB removal from the aqueous solution occurred in the presence of H2O2 (with 300 mg.L−1), with 1.0 g.L−1 of catalyst, at neutral pH and under solar radiation. The stability of the catalyst was confirmed by its reuse in four consecutive cycles. A kinetic mechanism for photochemical reaction has been proposed, which explains the experimental results obtained.

An investigation of ultrasonic based hydrogen production

A comprehensive numerical study is performed to establish a link between the primary effect of the acoustic cavitation bubble activity and the consequent effect of the chemical kinetics mechanism associated with the sonochemical process. In this work, we studied a possible reaction kinetics mechanism for the sonochemical hydrogen production, which we called the sonohydrogen process. The reaction kinetics mechanism consists of 19 reversible reactions taking place inside the acoustic cavitation micro-bubble at different conditions. The simulation of the reaction kinetics is validated and utilized to quantify the amount of hydrogen produced by a single bubble that is initially saturated with water vapor/oxygen. The results from the bubble dynamics model and the chemical kinetics model are compared with two different experiments available in the literature. Furthermore, the work evaluated the energy efficiency of this technology to produce 1 μmol of hydrogen in kWh. The present results revealed that the bubble temperature governs the chemical reaction mechanism of the water vapor dissociation. The minimum bubble temperature required for a slight production of hydrogen is 3000 K, the hydrogen is in the range of 5.46E-06 – 8.59E-06 μmol/h. At the following conditions of an ultrasonic frequency of 20 kHz, an acoustic power of 30 W, and a bubble temperature of 6000 K, the amount of hydrogen produced is 1.05E-03 μmol/h. The higher the bubble temperature, the faster the chemical reaction rate, which will lead to a higher hydrogen production rate. In terms of performance, the sonohydrogen process produces 2.22E-02 μmol/kWh.

Selective conversion of CO2 to methanol over intermetallic Ga-Ni catalyst: Microkinetic modeling

The conversion of CO2 from industrial effluent flue gas streams into methanol will not only help in mitigating global warming but also provide a clean source of alternate energy. In this study, the microkinetic model for methanol synthesis from CO2/H2 on supported intermetallic Ga3Ni5 catalyst based on the single-site mechanism is presented. The reaction route (RR) analysis was used to develop a rate expression without any presumption of the most abundant reactive intermediate (MARI) and rate-determining steps (rds). The silica-supported Ga3Ni5 catalyst was prepared through co-precipitation method and characterized by various techniques. The developed kinetic model was tested, and its parameters were estimated with the experimental data obtained over the lab synthesized catalyst. From the results obtained, it was found that the hydrogenation of formate intermediate is the rds and surface adsorbed CO2 and H-atom were MARI of the system. Based on rds and MARI, the final kinetic expression was tested against experimental data for a wide range of temperatures. The calculated data from the kinetic expression was found to fit the experimental results well, thereby validating the kinetic parameters and reaction mechanism proposed in this study. In addition, based on a plug flow reactor model, the kinetic parameters predicted the theoretical CO2 conversion at high temperatures, thus, demonstrating the robustness of the rate expression and accuracy of kinetic parameters proposed in this study.

Kinetics and thermodynamics of synthesis of palm oil-based trimethylolpropane triester using microwave irradiation

Enhancement of reaction performance utilizing microwave irradiation has drawn so much interest due to its shorter reaction time and low catalyst loading. These advantages are particularly significant from kinetics and thermodynamics perspectives. This study aimed to investigate the kinetics and thermodynamics of microwave-assisted transesterification of palm oil-based methyl ester into biolubricant. The transesterification reaction of palm oil methyl ester (PME) and trimethylolpropane (TMP) was conducted at 110–130 °C for 90 min under vacuum condition. Sodium methoxide was employed as the catalyst at 0.6 wt% of reactants fixed at molar ratio of 4:1 (PME: TMP). The experimental data were fitted with the second-order reversible reaction kinetics mechanisms. The data were solved via Runge-Kutta 4,5 order using MATLAB software. Analysis on the data revealed that the reaction rate constants at temperatures of 110–140 ℃ were in the range of 0.01–0.63 [(w/w)(min)]−1, with standard errors of 0.0026–0.0228 within 99.99% prediction interval. Microwave-assisted reaction obtained 17.0 kcal/mol of activation energy. This method reduced activation energy by 49% as compared to the conventional heating. Activation energy and time-periodic energy assessment showed that the reaction was endothermic. The reaction at 130 °C is the easiest to activate. The positive Gibbs free energy (ΔG > 0) found using Eyring-Polanyi equation indicated that the transesterification was non-spontaneous and endergonic.

Kinetic Study on Microwave Magnetizing Roast of Fe<sub>2</sub>O<sub>3</sub> Powders

In this paper, the reaction kinetic mechanism of Fe2O3 powder containing carbon was studied by microwave magnetizing roast. Based on the temperature-rise curve and weight loss curve of Fe2O3 powder by microwave magnetizing roast, the kinetic parameters of Fe2O3 powder microwave magnetizing roast were calculated by non-isothermal methods. The controlling steps of different temperature-rising periods in microwave magnetizing roast process of Fe2O3 powder were calculated by the Achar-Brindley-Sharp-Wendworth method. The results indicated that the controlling step of microwave magnetizing roast was phase boundary reaction control of contracted cylinder in 250~450°C, and it was three-dimensional diffusion control of spherical symmetry in 450~650°C. The results showed that the starting temperature of reduction roasting of Fe2O3 powder was 250°C, which was lower than that under electrical heating, thereby, it proved in theory that microwave heating can enhance reaction rate.

Urea Injection and Uniformity of Ammonia Distribution in SCR System of Diesel Engine

Abstract The kinetic mechanism of chemical reaction was used to calculate the coupling of the fluid kinetics with the urea decomposition reaction and the SCR reaction kinetics. Combined with the engine test and simulation, the distribution uniformity of the urea injection and ammonia gas was studied. Through numerical simulation on urea spray and exhaust flow in Urea-SCR system, the flow field characteristics in whole after-treatment system are gotten. By using numerical calculation in different urea injection angle and orifice sizes, the urea-crystallization and ammonia distribution have been studied and the optimal urea spray angle and nozzle size are given.

Influence and assessment of AIBN on thermal hazard under process situations

Free radical polymerization is an effective method for large-scale production of various olefin polymers, in which the initiator is one of the emphases in the study of different chain reaction mechanisms in chemical industry. The azo compounds are widely used in organic synthesis to initiate chain reactions. Azos are divided into different types according to the applicable temperature range. 2,2′-Azobis(2-methylpropionitrile) is suitable for moderate temperatures and well known. In the past, the chemical and free radical reactions of 2,2′-Azobis(2-methylpropionitrile) have been studied. However, the kinetic model and reaction mechanism of initiators under process conditions are still lacking. The thermal hazard characteristics evaluated by process situation of 2,2′-Azobis(2-methylpropionitrile) were discussed in this study. The kinetics analysis on AIBN is based on detailed information including rate constants, reaction orders and activation energies of the decomposition reaction. Simulated heat exchange patterns of initiators between bulk packaging and the environment can be used to collect relevant heat hazard parameters. The results of the analysis are directly related to the storage and transportation safety of the 2,2′-Azobis(2-methylpropionitrile). Finally, a series of evaluation models about the thermal safety of initiators are constructed and analyzed by simulating the runaway modes of the 2,2′-Azobis(2-methylpropionitrile) at different temperatures.

Study on the Pyrolysis Kinetics and Mechanisms of the Tread Compounds of Silica-Filled Discarded Car Tires.

The disposal of used automobile tires is a major waste concern. Simply stacking tires and allowing them to decompose will harbor breeding mosquitoes that spread viruses, whereas burning them will release acidic and toxic gases. Therefore, one viable option is pyrolysis, where elevated temperatures are used to facilitate the decomposition of a material. However, the lack of theoretical support for pyrolysis technology limits the development of the pyrolysis industry when it comes to discarded tires. The purpose of this research is to put forward a brand-new multi-kinetic research method for studying materials with complex components through the discussion of various kinetic research methods. The characteristic of this kinetic research method is that it is a relatively complete theoretical system and can accurately calculate the three kinetic factors considered during the pyrolysis of multicomponent materials. The results show that the multi-kinetic research method can obtain the kinetic equation and reaction mechanism for the pyrolysis of tires with high accuracy. The pyrolysis process of this compound was divided into two stages, Reaction I and II, where the kinetic equation of Reaction I was , with an activation energy of 155.26 kJ/mol and a pre-exponential factor of 5.88 × 109/min. Meanwhile, the kinetic equation of Reaction II was , while its activation energy was 315.40 kJ/mol and its pre-exponential factor was 7.86 × 1017/min. Furthermore, based on the results of the research analysis, the reaction principles corresponding to Reaction I and Reaction II in the pyrolysis process of this compound were established.

Computational analysis of premixed methane-air flame interacting with a solid wall or a hydrogen porous wall

The process of flame-wall interaction for premixed methane-air flames is investigated by direct numerical simulation. The flames propagate towards an isothermal, chemically inert surface, consisting of either a solid impermeable wall (IW) material or a hydrogen-permeable wall (PW) material. With the PW, hydrogen seeps into the domain and participate as a secondary, non-premixed fuel. The skeletal methane-air chemical reaction kinetics mechanisms of Smooke and Giovangigli and DRM22 are used with the S3D code to study the major reactions controlling the flame-wall interactions (FWI). Initially, results of said mechanisms are compared to the complete GRI 3.0 scheme. The configurations are investigated for two temperatures, 600 K and 750 K, of the wall and the unburnt gas, and for initial equivalence ratios of 0.5, 1.0 and 1.5. Results for IW are similar to previous FWI studies. The flame quenches at the wall, with maximum heat release and wall heat flux occurring close to the quenching instance. For the PW cases, the flame quenches before reaching the wall. This is explained by the mutual effects of convective heat transfer away from the wall and flame due to permeation, a high concentration of hydrogen and high local fuel-to-oxidizer ratio, reduced temperature and reduced reaction heat release. The quenching definition and flame position are based on OH radicals concentration. The observed maximum wall heat flux is much lower than for IW, and occurs some time after quenching. A discussion about the quenching process indicates that a definition based on maximum wall heat flux is inappropriate.

3D Kinetics, an Upgrade to the Classical Michaelis‐Menten Method

Most of the kinetic data published nowadays are derived from different extensions of what Michaelis and Menten introduced to this field more than hundred years ago. The key assumption to Michaelis‐Menten kinetics is the steady state approximation where the change in the concentration of any enzyme‐substrate intermediate complex is assumed to be zero. This assumption has two underlying requirements with the first one being [S]≫[E] and the second being the limitation of the reaction time to the short initial linear region of the progress curve. The historical need for the steady state assumption was to simplify data treatment to such a degree that the analytical mathematics could be done without need for an abundance of computing power. However, with the computation power at our disposal today, none of the limiting assumptions are necessary anymore especially considering that many of these assumptions rarely hold true. The time course of aldehyde oxidase with one of it substrates, O6‐benzylguanine, is provided here as an example of the statement above. In addition to the obvious instant curvature in the time course plot which makes it difficult to identify the precise linear region, the simulation done on the ES complex based on the data further proves how the steady state approximation is a poor assumption to make especially during the shorter “linear” region of the progress curve as this region is the one in which the concentration of ES is changing the most (Figure 1). The easiest way to approach kinetic data today is to parameterize realistically complex kinetic reaction mechanisms through 3D kinetics. 3D numerical modeling uses the data derived from experiments that monitor the product formation as a function of both incubation time and substrate concentration. With this approach, scientists would be able to derive both the traditional Km and Vmax values as well as the micro‐rate constants related to each step of the enzymatic reaction (Figure 2).Support or Funding InformationThis work was supported by the National Institutes of Health grant: GM100874A‐1) Numerical fitting of product formation with two different models (A‐2 and A‐3) shows that Michaelis Menten (dashed line) does not fit the data well over longer period of time. B) Simulation of the ES complex through the A‐3 model shows a significant change in this species’s concentration over the initial period of the time course where it is assumed to be a constant in deriving the Michaelis‐Menten equation.Figure 1A) Numerical fitting of the product formation over time of different initial substrate concentrations with the kinetic model provided on the right side of the graph to solve for the micro‐rate constants k3‐k5. B) Classical kinetic parameters such as Km and Vmax can be obtained from the same data set by plotting the rate versus substrate concentration for each time point.Figure 2

Linking reaction mechanisms and quantum chemistry: An ontological approach

In this paper, a linked-data framework for connecting species in chemical kinetic reaction mechanisms with quantum calculations is presented. A mechanism can be constructed from thermodynamic, reaction rate, and transport data that has been obtained either experimentally, computationally, or by a combination of both. This process in practice requires multiple sources of data, which raises, inter alia, species naming and data inconsistency issues. A linked data-centric knowledge-graph approach is taken in this work to address these challenges. In order to implement this approach, two existing ontologies, namely OntoKin, for representing chemical kinetic reaction mechanisms, and OntoCompChem, for representing quantum chemistry calculations, are extended. In addition, a new ontology, which we call OntoSpecies, is developed for uniquely representing chemical species. The framework also includes agents to populate and link knowledge-bases created through the instantiation of these ontologies. In addition, the developed knowledge-graph and agents naturally form a part of the J-Park Simulator (JPS) – an Industry 4.0 platform which combines linked data and an eco-system of autonomous agents for cross-domain applications. The functionality of the framework is demonstrated via a use-case based on a hydrogen combustion mechanism.

A reduced chemical kinetic reaction mechanism for kerosene-air combustion

Development of a new reduced chemical kinetic reaction mechanism for kerosene-air combustion is presented. The new mechanism uses a modular based development technique and is a further development on previously presented kerosene-air mechanisms. The new mechanism consists of 30 species and 77 irreversible reactions and is developed to accurate reproduce key flame parameters yet being small enough to be used in finite rate Large Eddy Simulations (LES), Direct Numerical Simulations (DNS) and in Reynolds Average Navier-Stokes (RANS) simulations. The well-proven development technique uses a refined fuel breakdown oxidation sub-mechanism, a simplified C2 intermediate species sub-mechanism and a more detailed set of reactions for the H/C1/O chemistry. The mechanism has been modified to be able to predict ignition delay times for a wide range of temperatures, including in the negative temperature regime.The mechanism has been evaluated for combustion parameters related to flame propagation and ignition over a wide range of equivalence ratios, initial gas temperatures and pressures. Agreements to experimental data and a set of detailed and skeletal mechanisms are good for all target parameters. The proposed mechanism shows good agreement at a computational cost far below all tested reference mechanisms, making it highly suitable for use in combustion computational fluid dynamic (CFD) simulations.

Kinetic reaction and deactivation studies on thermocatalytic decomposition of methane by electroless nickel plating catalyst

Hydrogen produced by thermocatalytic decomposition of methane is a promising approach to reduce the greenhouse gas effects on environment. A series of experiments were carried out to study the intrinsic kinetic reaction rate, reaction mechanism and catalyst deactivation in methane decomposition using electroless nickel plating on SBA-15 as the catalyst in a fixed bed reactor. The experiments were conducted under atmospheric pressure at a temperature range of 525–600 °C and different methane contact times based on varying methane flow rates over a catalyst bed of fixed weight and depth. The reaction order of kinetic reaction rate was found to be 2. The experimental value of the activation energy for the overall methane decomposition reaction was 113.993 kJ mol−1. A deactivation activity model was used and it showed good agreement with the experimental catalytic activities during the catalyst deactivation reaction for the range of experimental conditions. A deactivation order of 0.5 and an activation energy for the deactivation reaction of 147.870 kJ mol−1 were obtained. Transmission electron microscopy (TEM) was carried out to characterize the deactivated catalysts. TEM micrographs showed that the main deactivation mechanism using electroless nickel plating as catalyst was due to coking which resulted in a loss of active sites.

Process Modelling and Simulation of Fast Pyrolysis Plant of Lignocellulosic Biomass Using Improved Chemical Kinetics in Aspen Plus®

The successful operation of biomass pyrolysis plant on an industrial scale would showcase and promote the possibility of practical decarbonizing energy projects. This work presents a comprehensive Aspen Plus® modeling work of fast pyrolysis processes for lignocellulosic biomass based on kinetic reaction mechanisms. The simulation uses mass and energy balance calculations to forecast the product yields and composition depending on different sets of operating conditions (temperature, residence time) and feedstock composition includes conventional components, nonconventional components, and solids component of lignocellulosic biomass. The reaction kinetic models are developed from the principle of biomass pyrolysis using data available from the literature. The product yield from a biomass pyrolysis pilot plant is used to demonstrate the validation of the model. The results show a high correlation of the results for both slow and fast pyrolysis processes compared with those from the pilot plant and the previous works. The simulation model is found to be able to correctly predict fast pyrolysis products’ yields within the typical range of operation considered (high reaction temperatures with low residence times). In conclusion, the model proved to be suitable for predicting fast pyrolysis reactions for lignocellulosic biomass feedstock and can be used for estimating the trend of pyrolysis products without the need for experimental data with t-test of differential of product yield’s trend at 95 % confidence interval as 0.00327. This fast pyrolysis model offers rapid assessment for energy projects associated with the transition towards low-carbon development in Asia.

Determination of pyrolysis characteristics and thermo-kinetics to assess the bioenergy potential of Phragmites communis

This study systematically investigated the bioenergy potential of Phragmites communis, a large perennial grass found in wetlands. The biofuel physicochemical characteristics of Phragmites were determined and a pyrolysis kinetic study and thermal behaviour analysis were performed. Thermal degradation was investigated by exposing dried and powdered biomass to different heating rates (10, 20, 30, and 40 ℃/min) using TG-FTIR-GC/MS. The pyrolysis process of Phragmites communis occurred in three stages, with maximum mass loss (59.32%) during the main stage of devolatilization in the range of 150–500 ℃. The iso-conversional models of Flynn-Wall-Ozawa method was applied to explain the reaction chemistry, with good statistical confidence (R2 ≥ 0.9). The kinetic reaction mechanism of the three sub-stages predicted by the master-plots is f(α) = 3α2/3; f(α) = 3α3/4; and f(α) = 2 (1 − α)2, respectively. The coupled TG-FTIR-GC/MS analyses allowed identification of the volatile species as the major pyrolytic products, including acids, ketones, furan, phenols, benzene, furan, and alkane. Based on the thermodynamic parameters of Phragmites communis, this material is a promising feedstock for bioenergy production, and this study provides theoretical and practical guidance for effective energy and resource utilization.

OntoKin: An Ontology for Chemical Kinetic Reaction Mechanisms.

An ontology for capturing both data and the semantics of chemical kinetic reaction mechanisms has been developed. Such mechanisms can be applied to simulate and understand the behavior of chemical processes, for example, the emission of pollutants from internal combustion engines. An ontology development methodology was used to produce the semantic model of the mechanisms, and a tool was developed to automate the assertion process. As part of the development methodology, the ontology is formally represented using a web ontology language (OWL), assessed by domain experts, and validated by applying a reasoning tool. The resulting ontology, termed OntoKin, has been used to represent example mechanisms from the literature. OntoKin and its instantiations are integrated to create a knowledge base (KB), which is deployed using the RDF4J triple store. The use of the OntoKin ontology and the KB is demonstrated for three use cases-querying across mechanisms, modeling atmospheric pollution dispersion, and as a mechanism browser tool. As part of the query use case, the OntoKin tools have been applied by a chemist to identify variations in the rate of a prompt NOx formation reaction in the combustion of ammonia as represented by four mechanisms in the literature.

Effects of double-jet positions on detonation initiation characteristics

In order to initiate the detonation waves efficiently, the ignition method of two jets was proposed and utilized to initiate the mixture of H2/Air in a detonation chamber. The numerical simulation based on H2/Air detailed chemical reaction kinetics mechanism was carried out to study the influence of the two jets arrangement positions on detonation initiation. The reliability of the numerical simulation was verified by the calculation results of CEA and the experimental results. The simulation results indicated that the distance from the first jet to left end of the detonation chamber (L1) and the distance between the two jets (L2) showed significant influence on the detonation initiation process and the distribution of the reflected shock wave. The reflected wave formed by the reflection between the detonation waves from the jet tubes and the wall contributed to the propagation of the flame and the generation of the plane detonation waves. The OH concentration curve and the temperature curve were coupled. The formation and the consumption of OH was one of the main factors which controlling the detonation waves and the temperature behind the detonation waves. When L1 was greater than 10 mm, the velocity of the detonation waves decreased as L1 increased. Furthermore, when L1 and L2 both equaled to 10 mm, the velocity of the detonation wave was maximized.

Prediction of homogeneous combustion by modification of the fuel combustion mechanism in a DME fueled CI engine

This study was performed to predict numerically the homogeneous combustion characteristics where the fuel combustion mechanism was modified in a DME fueled CI engine. To achieve this, detailed chemical kinetic reaction mechanisms were used for the prediction of homogeneous combustion of hydrocarbon fuels (diesel and DME). The results were compared in terms of cylinder pressure, heat release rate, and CO and NOX emissions. Calculations were performed using the detailed chemical kinetic mechanism, including 671 species and 2933 reactions for n-heptane (n-C7H16) and 96 species and 453 reactions for dimethyl ether (CH3OCH3). In addition, a modified NOX mechanism was added to investigate the accumulated results of NOX production. The engine experiments were conducted using a single cylinder CI engine with a common-rail injection system. The fuel injection quantity was set to 8 mg, and the injection pressure was maintained at 50 MPa at 1500 RPM. In this study, DME and diesel fuels were injected for inducing the homogeneous combustion at BTDC 60 and BTDC 40 degree. The modified mechanism hardly affected the overall chemical reactions, which was almost identical in comparison to the results of the conventional mechanism. In addition, the ignition delay was slightly faster in the calculation of the n-heptane mechanism because it showed that a high reaction rate was involved in the fuel oxidation and reaction of the NTC region. The combustion and exhaust emission characteristics of the homogeneous combustion simulation were in good agreement with the engine experimental results at BTDC 60 degree of injection timing, but the CO emission was over predicted when the n-heptane mechanism was employed in the DME combustion simulation. The chemical reactions of the DME combustion process were dominated by the forward reaction, which were CH3OCH3+O→CH3OCH2+OH and CH3OCH3+OH→CH3OCH2+H2O reactions. Furthermore, this study confirmed that an increase of OH radicals promotes the fuel oxidation reaction, and it can influence the combustion temperature, which also affected the processes of NOX production and CO oxidation reactions.

Automatic kinetic model generation and selection based on concentration versus time curves

AbstractThe goal of the paper is to automatize the construction and parameterization of kinetic reaction mechanisms that can describe a set of experimentally measured concentration versus time curves. Using the framework and theorems of formal reaction kinetics, first, we build a set of possible mechanisms with a given number of measured and unmeasured (real or fictitious) species and reaction steps that fulfill some chemically reasonable requirements. Then we fit all the corresponding mass‐action kinetic models and offer the best one to the chemist to help explain the underlying chemical phenomenon or to use it for predictions. We demonstrate the use of the method via two simple examples: on an artificial, simulated set of data and on a small real‐life data set. The method can also be used to do a kind of lumping to generate a model that can reproduce the simulation results of a detailed mechanism with less species and thereby can largely accelerate spatially inhomogeneous simulations.

Reduction of large-scale chemical mechanisms using global sensitivity analysis on reaction class/sub-mechanism

The reliable chemical mechanisms with compact scale play an important role in engine modeling. In this research, a new method was presented to reduce the large-scale reaction kinetic mechanisms through the global sensitivity analysis on the reaction classes/sub-mechanisms in detailed mechanisms. In the present method, the importance of each reaction sub-mechanism in a detailed mechanism was first assessed using the Morris method. Then, the crucial reaction classes in the fuel-specific sub-mechanism were identified based on their significance on the detailed mechanism predictions and their coupling relationship using the Morris method and the path sensitivity analysis. Third, the reactions in the unimportant sub-mechanisms and the isomers in the dominant reaction classes of the fuel-specific sub-mechanism were lumped. The scale of the final mechanism was reduced further by removing the unimportant reactions in the important small-molecule sub-mechanism, and the initial reduced mechanism was obtained. Final, the optimization of the reaction rate constants in the fuel-specific sub-mechanism was performed under their uncertainties to improve the performance of the reduced mechanism over a wide temperature range. With the proposed method, a detailed iso-cetane mechanism including 1107 species and 4469 reactions was reduced. The reduced mechanism contains only 56 species and 131 reactions. Good agreements between the reduced mechanism and the detailed mechanism were achieved on the predicted results of ignition delay times and species concentrations over wide conditions.