Pyrolysis Kinetic Analysis Research Articles

Microscopic Phase Structure of Mo-based Catalyst and Its Catalytic Activity for Soot Oxidation

The MoO3 catalysts supported on nano-scale TiO2 with various loading rates (5%, 10%, 20%, and 40%) were prepared by an impregnation method. The phase structures of nano-scale MoO3/TiO2 catalysts were characterized by Brunner-Emmet-Teller, Fourier Transform Infrared Spectra, X-ray Diffraction, and Scanning Electron Microscope. The oxidation activities of catalysts over diesel soot were performed in a Thermogravimetric Analysis system. The kinetics of the catalytic oxidation process was analyzed based on Starink method. The characterization results showed that the phase structure of MoO3 supported on TiO2 depends heavily on the molybdenum contents, which put great effects on soot oxidation. The orthorhombic crystal system (α-MoO3) appeared on the surface of the catalysts when the MoO3 exceeds 10%. Due to the low melting point and good surface mobility of MoO3, the catalytic activity was increased and the characteristic temperatures were decreased with the increase in MoO3 contents. As a result, the activities of catalysts with different loading rates for soot oxidation can be ranked as: Mo5<Mo10<Mo20

Phy-chemical Attributes of Nano-scale V2O5/TiO2 Catalyst and Its’ Effect on Soot Oxidation

The V2O5 catalysts which supported on nano-scale TiO2 with variation of vanadium contents (5%, 10%, 20% and 40%) were prepared by an incipient-wetness impregnation method. The phase structures of nano-scale V2O5/TiO2 catalysts with different loading rates were characterized by Scanning electron microscope (SEM), X-Ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectra. The oxidation activities of catalysts over diesel soot were performed in a themogravimetric analysis (TGA) system. The kinetics of the catalytic oxidation process were analyzed based on Flynn-Wall-Ozawa method. The characterization results showed that the phase structure of V2O5 supported on TiO2 depends heavily on the vanadium contents, which will put great effects on the catalytic performances for soot oxidation. At a low vanadium loading rates (V5-V20), active species exist as monomers and polymeric states. At a high loading rate (V40), the crystalline bulk V2O5 covers the surface of TiO2. The formed crystal structure occupied the active sites and led a decreasing in the catalytic effect. By comparing the characteristics temperatures of soot oxidation over V2O5 catalysts, the catalytic activities of catalysts with different loading rates for soot oxidation can be ranked as: V5 < V10 < V40 < V20. Via pyrolysis kinetics analysis, it is revealed that the activation energy of soot oxidation is minimum when the vanadium loading rates is 20%, which is fit well with the TG experimental results. The consistency of pyrolysis kinetics and TG experimental results confirm that the best activity catalyst is V20 in discussed catalysts of this paper, which is nearest to the monolayer dispersion saturated state of V2O5/TiO2 catalyst. Moreover, it convincingly demonstrate the obvious threshold effect in V2O5 catalysts.

Structural Characterization and Pyrolysis Behavior of Cellulose and Hemicellulose Isolated from Softwood Pinus armandii Franch

Cellulose and hemicellulose were isolated directly from softwood Pinus armandii Franch by the alkali method for pyrolysis mechanism study. Structural characterization based on FTIR, 1H NMR, and 13C NMR showed that the hemicellulose was mainly composed of galactoglucomannan and arabinoxylan with abundant branches, while the cellulose was mainly composed of β-1,4-glucan with a few residual hemicellulose fragments. Pyrolysis of extracted cellulose showed high char yield due to the lower crystallinity. Hemicellulose pyrolysis showed a shoulder peak at low temperature and high char yield because of its abundant branches. A double-Gaussian distributed activation energy model was introduced for pyrolysis kinetics analysis. The devolatilization process for both cellulose and hemicellulose was dominated by a parallel decomposition reaction pathway. The distributions of their pyrolysis products were analyzed by Py-GC/MS. It is suggested that the utilization of isolated sample as model compound could give a better u...

Evaluation of Thermal Decomposition and Pyrolysis Process Parameters on Typical Polymer Materials in Solid Waste

Pyrolysis of plastic polypropylene (PP), plastic poly (vinyl chloride) (PVC) and latex gloves in solid waste was studied using thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TG-FTIR). Pyrolysis characteristic and kinetic analysis of different materials were discussed. From TG and DTG curves, the pyrolysis of plastic PP turned out to be the most concentrative, followed by latex gloves and plastic PVC. For volatile species analysis, evolved volatile products from all these three materials included alkene, alkane, carbon dioxide, and water, especially, for plastic PVC, HCl was the most volatile species; among the evolved species, HCl can be easily identify, but the different of standard spectrum for alkene or alkane is no significant, thus it is difficult to clearly identification alkane or alkene from the mixed gas. For kinetic analysis, kinetic parameters for the first reaction based Arrhenius theory was got.

Pyrolysis characteristics and pyrolysis products separation for recycling organic materials from waste liquid crystal display panels

Waste liquid crystal display (LCD) panels mainly contain inorganic materials (glass substrate with indium-tin oxide film), and organic materials (polarizing film and liquid crystal). The organic materials should be removed beforehand since the organic matters would hinder the indium recycling process. In the present study, pyrolysis process is used to remove the organic materials and recycle acetic as well as and triphenyl phosphate (TPP) from waste LCD panels in an environmental friendly way. Several highlights of this study are summarized as follows: (i) Pyrolysis characteristics and pyrolysis kinetics analysis are conducted which is significant to get a better understanding of the pyrolysis process. (ii) Optimum design is developed by applying Box–Behnken Design (BBD) under response surface methodology (RSM) for engineering application which is significant to guide the further industrial recycling process. The oil yield could reach 70.53wt% and the residue rate could reach 14.05wt% when the pyrolysis temperature is 570°C, nitrogen flow rate is 6Lmin−1 and the particle size is 0.5mm. (iii) Furthermore, acetic acid and TPP are recycled, and then separated by rotary evaporation, which could reduce the consumption of fossil energy for producing acetic acid, and be reused in electronics manufacturing industry.

Influence of pyrolysis condition and transition metal salt on the product yield and characterization via Huadian oil shale pyrolysis

In our work, a series of experiments on pyrolysis of the large particle oil shale (6–15mm) were carried out in a self-made retorting pyrolyzer, in order to obtain the optimal final pyrolysis temperature of Huadian oil shale and evaluate the catalytic performance of transition metal salts (CoCl2·6H2O, MnSO4·H2O) in promoting the shale oil yield and product characteristic. The experiment results showed that the retorting temperature significantly influenced the shale oil yield. The maximum oil yield appeared in 520°C with the result of 21.59wt%. Meanwhile, the higher retorting temperature promoted the more production of alkanes/olefins, which led to the increase of alkanes from 20.46% to 32.44%. Moreover, the use of CoCl2·6H2O salt further increased the oil yield. The pyrolysis behavior and kinetic analysis indicated the transition metal iron could act as the activation center to accelerate the breakdown of chemical bonds in organic matters. In addition, the addition of the Co salt significantly enhanced the formation of aromatic hydrocarbons in the shale oil, which increased about 18% compared to that of non-catalytic pyrolysis. It had demonstrated the Co iron could increase the selectivity of aromatic hydrocarbons and promote olefin aromatization. The acid compounds were observed in the oil produced from the catalytic pyrolysis of MnSO4·H2O, which suggested that it was not suitable to be regarded as the candidate catalysis.

Effects of Torrefaction on the Pyrolysis Behavior and Bio-Oil Properties of Rice Husk by Using TG-FTIR and Py-GC/MS

The properties of biomass directly result in the quality of bio-oil. Torrefaction pretreatment is an alternative and promising approach for biomass updating to produce high-quality bio-oil. The effects of torrefaction on the pyrolysis of rice husk were investigated using thermogravimetry–Fourier transform infrared spectroscopy (TG-FTIR), a pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), and a fast pyrolysis device. The results show that with increasing torrefaction temperature, the weight loss decreases and the shoulder peaks of torrefied rice husk in DTG curves fade away. The pyrolysis characteristics and kinetics analysis of torrefied rice husk at 290 °C are unique. Three-dimensional FTIR analysis of the evolved gases clearly shows the generation properties of individual volatile components. Fast pyrolysis of torrefied rice husk produces improved bio-oil low moisture content and high heat value. Py-GC/MS analysis shows that the acidic content does not increase, while the content of many highly valued products (e.g., levoglucose) increases greatly.

Pyrolysis characteristics and kinetic analysis of different dewatered sludge

Pyrolysis behavior and kinetic properties of four different sludge, including raw sludge and three sludge respectively dewatered with FeCl3/CaO, FeCl3/CaO/coal and Fenton’s reagent (Fe2++H2O2)/CaO, were analyzed by using thermogravimetry coupled with Fourier transform infrared spectrometry (TG-FTIR). The results show that organics of raw sludge mainly decomposed at 378–676K, and the decomposition temperature of conditioned sludge was prolonged to 823K. Addition of coal and catalysis of CaO/ferric salt both promoted sludge pyrolysis, leading to more NH3, CH4 and CO productions. Compared with dry sludge, wet sludge pyrolysis was hard to finish completely, and the first peak of organics’ decomposition appeared at higher temperature (about 573K). Additionally, the global reaction model was suited to determine kinetic parameters, which showed that dry sludge conditioned with more CaO addition had higher E values than those of dry raw sludge. Opposite results were obtained when sludge samples were wet.

Investigation on Pyrolysis Characteristic and Kinetic Analysis of Lignocellulosic Biomass Model Compound

Lignocellulosic biomass gasification is considered as one of the effective methods for transforming scattered biomass into heat, power and various chemicals. As a fundamental step for biomass gasification, pyrolysis has remarkable influence on products distribution and char reactivity during the further step. Further research on the pyrolysis process of lignocellulosic biomass is beneficial to optimize and promote the process of gasification. In this paper, pyrolysis characteristic of a kind of lignocellulosic biomass model compound (cellulose) was explored through thermogravimetric analyzer. The temperature was from 25 °C to 950 °C under various heating rates (10, 20, 40 °C·min-1) with nitrogen atmosphere. A three step selecting method for mechanism function was used to check out the optimum model from fifteen kinds of most frequently used mechanisms. The results indicated that under various heating rates, the optimum mechanism model for the cellulose in this paper was different. The values of activation energy and frequency factor for cellulose pyrolysis calculated by the three step method in this paper under 10, 20, 40 °C·min-1 were 245.95, 212.09 and 144.27 kJ·mol-1, 8.47E+17, 5.35E+18 and 1.20E+11 s-1, respectively.

Pyrolysis kinetic and product analysis of different microalgal biomass by distributed activation energy model and pyrolysis-gas chromatography-mass spectrometry.

To assess the energy potential of different microalgae, Chlorella sorokiniana and Monoraphidium were selected for studying the pyrolytic behavior at different heating rates with the analytical method of thermogravimetric analysis (TG), distributed activation energy model (DAEM) and pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS). Results presented that Monoraphidium 3s35 showed superiority for pyrolysis at low heating rate. Calculated by DAEM, during the conversion rate range from 0.1 to 0.7, the activation energies of C. sorokiniana 21 were much lower than that of Monoraphidium 3s35. Both C. sorokiniana 21 and Monoraphidium 3s35 can produce certain amount (up to 20.50%) of alkane compounds, with 9-Octadecyne (C18H34) as the primary compound. Short-chain alkanes (C7-C13) with unsaturated carbon can be released in the pyrolysis at 500°C for both microalgal biomass. It was also observed that the pyrolysis of C. sorokiniana 21 released more alcohol compounds, while Monoraphidium 3s35 produced more saccharides.

Analysis of Pyrolysis Kinetics and Energy Content of Agricultural and Forest Waste

Selected agricultural and forest wastes included rice husk, coconut husk, cashewnut shell, eucalyptus, pine and mangrove were used for thermal characterization. The studied materials have heating value between 13 and 23 kJ/kg, such that the biomass material can be used as a fuel by directly burning, but their energy content is lower as compared to coal and other fossil fuels. The energy content of the biomass material can be improved through pyrolysis process for the mentioned materials, the cashew nut shell had higher energy content than other biomass material due to its high hydrogen to carbon ratio and low oxygen to carbon ratio. Thermochemical characteristic depicted high degradation at a heating rate of 10 K/min. All studied materials except mangrove and pine, maximum degradation occurred at 5 K/min. The reactivity of coconut husk was highest whilst cashew nut shell had the least reactivity. The activation energy for cashew nut shell obtained was 336.41 kJ/mole and the activation energy of the other biomass ranged between 220 and 130 kJ/mol. The coconut husk, pine, eucalyptus and rice husk are more reactive than mangrove and cashewnut shell.

Pyrolysis kinetic study of Huadian oil shale, spent oil shale and their mixtures by thermogravimetric analysis

The pyrolysis kinetics of Huadian oil shale, spent oil shale obtained from near-critical water extraction experiments and their mixtures were investigated using thermogravimetric analysis (TGA). Experiments were performed at four different heating rates of 2, 10, 20 and 50Kmin−1 from ambient temperature to 850°C at under atmospheric pressure and nitrogen flux. The results demonstrated that the thermal decomposition of oil shale, spent oil shale and their mixtures involved three degradation steps. The temperature of the maximum degradation rate (Tmax) of the oil shale and mixtures shifted toward higher temperature with the increase of heating rate. The extent of interactions during co-pyrolysis was confirmed by comparing the experimental result with the theoretical one. Different thermogravimetric data were analyzed by integral method. According to the pyrolysis kinetic analysis, the apparent activation energy of spent oil shale and mixtures was lower than that of oil shale. The values of the obtained apparent activation energy of the mixtures decreased with an increasing spent oil shale fraction because of the decreasing of the macromolecular organic matters which needed much energy during the thermal decomposition. The results are reasonable to conclude that the spent oil shale was helpful for the degradation of oil shale in the mixture.

Pyrolysis kinetics and combustion of thin wood by an advanced cone calorimetry test method

Pyrolysis kinetics analysis of extractives, holocellulose, and lignin in the solid redwood over the entire heating regime was possible by specialized cone calorimeter test and new mathematical analysis tools. Added hardware components include: modified sample holder for the thin specimen with tiny thermocouples, the methane ring burner with stainless-steel mesh above cone heater, and the water vapor sensor in heated gas sampling lines. Specialized numerical deconvolutions were applied to the oxygen and water vapor analyzer signals to synchronize with the rapid-responding CO/CO2 analyzer signals. From this data, the mass flow rates of carbon, hydrogen, and oxygen within the wood volatiles as function of time were obtained, which allowed deducing the mass flow rate of significant molecules of wood volatiles that have their origins in the wood constituents of extractives, holocellulose, and lignin. Accurate analytical solution of pyrolysis kinetics of appropriate competitive reactions that continuously conserved carbon, hydrogen, and oxygen mass flow rates was obtained for piecewise exponentially-shaped, spatially uniform temperature within the specimen as implemented conveniently in MS Excel spreadsheet.

Evaluation of oil potential and pyrolysis kinetics of renewable fuel and shale samples by Rock-Eval analyzer

A possibility for preliminary evaluation by Rock-Eval analysis of oil potential and pyrolysis kinetics of six representatives of renewable fuel and two Estonian shales is described. The amount of hydrocarbons volatilised from thermolabile ingredients of the samples at 300 °C (S1) is found to increase from 1.1 to 66.3 mg/g in the row: Dictyonema argillite < Kukersite < peat < pine sawdust < pine bark < willow < reed ≈ spruce needles. The total oil potential by pyrolysis at 300–650 °C (S1 + S2) increases from 47.4 to 367 mg/g in the row: Dictyonema argillite < peat < reed < pine bark < willow < spruce branches < pine sawdust < Kukersite. An increase in oxygen index (OI) decreases the temperature at the pyrolysis maximum rate ( T max) and S2 but increases S1 of the samples according to relationships approximated to linear regressions. Relationship between hydrogen and oxygen contents expressed by an increase in atomic ratio of (H/C) daf with that of (O/C) daf in Van Krevelen diagram for the initial samples is opposite to a decrease in HI with increase in OI for the volatiles estimated by Rock-Eval analysis. First-order kinetic models are proposed to estimate the values of apparent activation energy ( E) and frequency factor ( A) for evolution of total hydrocarbons, for release of hydrocarbons from thermolabile ingredients, and for prediction of current yields of hydrocarbons in time and temperature basing on S1, S2, T max at one heating rate. A linear relationship is revealed between the pyrolysis kinetic constants, E (kJ/mol) and A (1/min), of the samples studied: ln A = 0.228(±0.010) E − 4.46(±1.61).

Pyrolysis Kinetics of Asphaltite by Thermal Analysis

Pyrolysis properties and kinetic analysis of asphaltite were investigated by means of thermogravimetry (TG) and derivative thermogravimetry (DTG). Thermal experiments were carried out from ambient temperatures to 1000°C in nitrogen atmosphere at different heating rates. TG/DTG curves showed that the decomposition proceeds through two steps with DTG peaks corresponding to the weight loss obtained. Kinetic analysis of the asphaltite decomposition steps was carried out under non-isothermal conditions. Coats-Redfern method was used to analyze the TG data for determination of kinetic parameters. Activation energies (E a ) and pre-exponential factors (k o ) were calculated for different heating rates and compared.

Study on Biomass Pyrolysis Kinetics

Pyrolysis is the most fundamental process in thermal chemical conversion of biomass, and pyrolysis kinetic analysis is valuable for the in-depth exploration of process mechanisms. On the basis of thermal gravity analysis of different kinds of biomass feedstock, thermal kinetics analysis was performed to analyze the pyrolysis behavior of biomass. With the apparent kinetic parameters derived, a kinetic model was proposed for the main reaction section of biomass pyrolysis process. The pyrolysis characteristics of three kinds of biomass material were compared in view of corresponding biochemical constitution. Through model simulation of different pyrolysis processes, the diversity in pyrolysis behavior of different kinds of biomass feedstock was analyzed and pyrolysis mechanism discussed. The results derived are useful for the development and optimization of biomass thermal chemical conversion technology.