Gaseous Pyrolysis Products Research Articles

Improving the flame retardancy and smoke suppression of epoxy resins by introducing of DOPO derivative functionalized ZIF-8

The introduction of traditional flame retardants into epoxy resins (EP) usually generated a number of harmful smoke during burning. A novel flame retardant (dZIF-8) was synthesized via functionalization of zeolitic imidazolate frameworks-8 by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide derivatives (DMZ). The flame retardancy and smoke suppression of the dZIF-8 modified EP were studied. The combustion results showed that dZIF-8 can effectively reduce the fire risk of EP. Compared with the neat EP, the value of peak heat release rate (PHRR), the total smoke release rate (TSRR) and the maximum smoke density of the EP containing 2% dZIF-8 were decreased by 51%, 47% and 36%, respectively. The TG-FTIR results showed that the production of the pyrolysis gaseous products was inhibited by dZIF-8 during the decomposition of EP. In addition, the synergistic effect between the DMZ and the zeolitic imidazolate frameworks-8 improved the flame retardancy of the EP. Meanwhile, the increase in the flame-retardant performance of the dZIF-8 modified EP was caused by the quenching effect of the free radical containing phosphorus in gas phase and the charring effect of pyrophosphoric acid and zinc oxide in condensed phase. The morphology of dZIF-8 crystal changed from granular to laminar, indicating that the introduction of DMZ affected the crystal growth of dZIF-8. The laminar structure of the dZIF-8 provided a layered barrier effect during the burning process of EP.

A phosphorous/nitrogen/silicon containing diphenylphosphoramide silicon oil toward effective flame retardancy for polycarbonate with comparable mechanical properties

AbstractA P/N/Si containing diphenylphosphoramide silicone oil (PASO) was synthesized using amino phenyl silicone oil and diphenylphosphinyl chloride as raw materials. The as‐synthesized PASO displayed better flame retardancy toward polycarbonate (PC) meanwhile maintaining the mechanical performances of PC. At loading level of 1 wt% PASO, UL 94V‐0 rating and a high limited oxygen index value of 31% were achieved for the flame retardant composite in the presence of 5 wt% talc as anti‐dripping agent. Additionally, it gave a tensile strength of 65.5 MPa, elongation at break of 96.4%, and impact strength of 52.6 kJ/m2, which were comparable to the pure PC. The analysis of the char residue after cone calorimeter test and the pyrolysis gaseous products demonstrated that PASO exhibited flame retardant mechanism of both gas and condensed phases.

The Effect of Time on the Activation of Bayah Natural Zeolite for Application of Palm Oil Shell Pyrolysis

Oil palm shell (OPS) constitutes 60% of the waste generated during the processing of palm oil. However, OPS can potentially be converted into energy and chemicals through pyrolysis. The purpose of this study is to determine and analyse the effect of acid treatment time on the characteristics of natural zeolites, which were then applied to oil palm shell pyrolysis. The effect of the acid treatment time on the products of the pyrolysis was also studied. The acid treatment time was varied: 1, 3, and 5 hours. The crystallinity of the natural zeolites was determined by X-ray diffraction (XRD). Solid, liquid and gaseous pyrolysis products were observed. Proximate, ultimate, and heat analysis were performed on the solid product. The liquid product was characterised using gas chromatography-mass spectrometry (GC-MS). Gas Chromatography (GC) was performed to analyse the composition of the gases produced. The results obtained from this study indicate that longer reflux times reduced the crystallinity of the zeolites. The addition of the zeolite catalysts increased the liquid products of pyrolysis from 24.5 wt% over the parent to 24.6–37.1 wt% over the acid-treated natural zeolites. The reduction of oxygenated compounds in bio-oil was observed in the amount of acetic acid and acetone produced. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Sampling and concentration of polycyclic aromatic hydrocarbons from exhaust gases from a plant for synthesis of carbon nanomaterials

Currently, there is an increase in the production of carbon nanomaterials in the world, which is associated with their unique physical and mechanical properties and their use in various fields of science, industry and technology. Investigation of the chemical composition of waste gases from a propane-butane mixture pyrolysis unit during the synthesis of carbon nanomaterials is of scientific and applied value, since it allows one to study both the chemistry of the pyrolysis process of hydrocarbon mixtures and determine the degree of toxicity of waste gas from pyrolysis units. The quantitative determination of polycyclic aromatic hydrocarbons in the gaseous products of pyrolysis of a propane-butane mixture during the synthesis of carbon nanomaterials has shown that when sampling with a small amount of the Supelpak-2 adsorbent, which is widely used in international and domestic methods, efficient capture of multinuclear aromatic hydrocarbons is not ensured. Therefore, an important research issue is the development of a simple and effective method for sampling polycyclic aromatic hydrocarbons with their subsequent GC-MS analysis. The principal essence of the technique is the impregnation of two fiberglass filters with an organic low-volatile solvent – diethylene glycol, tetraethylene glycol or dimethyl sulfoxide. The latter is characterised by the highest extracting power in relation to polycyclic aromatic hydrocarbons. The developed technique makes it possible to increase the efficiency of capturing multinuclear aromatic hydrocarbons (with four or more rings in a molecule) to 96–98 % compared to a solid adsorbent under equal conditions (pyrolysis conditions, weight of adsorbent equal with filters impregnated with a solvent), where the degree of their extraction is 1–5 %. The established values of the degree of recovery of the measured components are explained by the high extracting ability of dimethyl sulfoxide in relation to multinuclear aromatic hydrocarbons.

Impact of Sawmill Waste on SO2 Emissions from Co-firing with Lignite

ABSTRACT Results of experimental studies of joint pyrolysis processes of a fairly typical and widely used in Russia and Poland 3B grade lignite and wood (sawdust of pine wood) are provided. The results were performed in order to substantiate the previously formulated hypothesis about the mechanism of suppression of sulfur oxides in the combustion products of such mixed fuels. Conclusions on the mechanism of SOx suppression were made after comparing the analysis results of the elemental composition of the initial lignite, wood, and ash remaining after the total completion of the studied mixtures pyrolysis processes, as well as X-ray phase analysis of the ash composition. It was found that the proportion of calcium and aluminum sulfates is higher in the solid pyrolysis products of mixtures of crushed coal and wood compared to the ash of homogeneous coal. Practical significance of the performed studies is that the obtained results of the experiments allow to justify the possibility of using wood as a part of mixed fuels based on 3B grade lignite as an additive that significantly reduces the yield of sulfur oxides during combustion of such fuels in the furnaces of steam and hot water boilers. It has been experimentally established that during high-temperature decomposition of two-component fuels based on 3B lignite in a mixture with fine wood biomass, the effect of reduction of sulfur oxide concentration in gaseous pyrolysis products of such mixtures is obtained due to the formation of calcium and aluminum sulfates in the ash of mixed fuels as a result of chemical reactions between gaseous and solid pyrolysis products of lignite and wood with participation of water vapor.

Influence of Forest Combustible Material on the Characteristics and Conditions of Ignition of Bio-coal Water Fuels

ABSTRACT The results of the experimental studies of the particles ignition of bio-coal water fuels have been presented. The experiments have been carried out on the setup providing an error level of not more than 6.1% of the main recorded characteristics. The effect of the temperature of the oxidizing agent and the characteristic size of the fuel drops on the duration of the induction period of the fuel compositions has been studied. It has been established that the introduction of the additives from forest combustible materials of three typical tree species leads to an acceleration of the ignition process of substantially flooded particles of bio-coal water fuels. According to the results of a detailed analysis of the frames of the videogram, it has been shown that the duration of the intensive chemical reaction of the gaseous pyrolysis products with a high-temperature oxidizer is not more than 0.02% of the entire induction period. Colloquium. One of the possible promising directions for the development of the coal technologies in the energy sector and for reducing the negative anthropogenic impact of the thermal power plants that burn coal is the use of the composite fuels (coal- water (CWF), organ coal- water, etc.) based on coal. But a number of the technological problems significantly complicate the use of such fuels in the energy sector. This is evidenced by a significant increase (over the past 10 years) in the number of the publications devoted to the problems of carbonic fuels. The ignition process of CWF is quite long (ignition delay time (tign) up to 20 seconds). The use of fuel with such a large induction period in a real practice is practically impossible. One of the possible options for reducing the tign value of the liquid composite fuels is the introduction of biomass into their composition. This is a new composite bio-coal water fuel (Bio-CWF). At present, there are practically no publications devoted to the experimental and theoretical studies of the ignition of Bio -CWF particles under conditions corresponding to the furnaces of the typical boiler units of the thermal power plants. The duration of the characteristic stages of ignition of Bio-CWF particles (made on the basis of coal, water and various types of biomass) is an important characteristic necessary for carrying out the experimental design works on the development of new innovative boiler units burning bio-coal water fuel.

Kinetics of thermal conversion of gaseous products of polypropylene pyrolysis using several detailed kinetic mechanisms

Thermal conversion (TC) of polypropylene pyrolysis gaseous products was studied numerically using three detailed kinetic mechanisms (DKMs) for the initial temperatures T0 ranging from 700 K to 1300 K and the initial pressure of 1 atm. Numerical simulations showed that all DKMs predicted similar qualitative behavior of the reacting mixture, however, they gave significantly different rates of the increase of the mole fractions of CH4 and H2 along with simultaneous decrease in C2+ hydrocarbons. The temperature increase in course of TC process was also found to be predicted differently by the three DKMs. Its characteristics depended on the initial temperature, some calculations showed smooth increase while in others explosionlike regimes were observed. The conversion products, along with methane and hydrogen, contained aromatic compounds C6+. Various DKMs gave significantly different TC characteristic times.

The effect of biomass addition on pyrolysis characteristics and gas emission of coal gangue by multi-component reaction model and TG-FTIR-MS

The pyrolysis experiment of biomass added to coal gangue was studied by thermogravimetric-Fourier transform infrared spectroscopy-mass spectrometry (TG-FTIR-MS) method. The multi-component reaction model was used to simulate the pyrolysis reaction of coal gangue and biomass. The most suitable model was obtained, and the pyrolysis mechanism was analyzed. According to the two-component reaction model of CG pyrolysis, the decomposition temperature range of components in CG is 340–800 °C and 400–620 °C. The five-component reaction model can well simulate the pyrolysis process of coal gangue and biomass. Meanwhile, the effects of different proportions of biomass in the mixture on the gas products of coal gangue pyrolysis were analyzed. It was found that the addition of biomass to coal gangue could promote the release of gaseous organic matter during pyrolysis. CG75PS25 only has a synergistic effect in the high temperature zone greater than 600 °C. CG25PS75 only has a synergistic effect in a small range of 230–300 °C, and there is an inhibitory effect in other temperature ranges. In general, there is an inhibitory effect between coal gangue and biomass on CO2 formation, which is of positive significance for greenhouse gas emission reduction.

Hierarchical core–shell SiO2@COFs@metallic oxide architecture: An efficient flame retardant and toxic smoke suppression for polystyrene

SiO2@3COFs@CuO and SiO2@3COFs@Fe2O3 are prepared in this study. Then SiO2 and its hybrids are incorporated into PS through solution blending method. The thermal stability, mechanical performance, combustion performance and smoke density of PS and its nanocomposite are investigated. The temperature at 5 wt% weight loss and the maximum weight loss rate of PS/SiO2@3COFs@ Fe2O3 (PS 4) under air are 15 and 14 °C higher than that of neat one, respectively. The glass-transition temperature of PS/SiO2@3COFs (PS 2) is 1.5 °C lower than that of PS, which can conclude that SiO2@3COFs contributes to impact strength of PS 0. The peak heat release rate (20.8%) and total heat release (14.0%) of PS 2 decreases further compared with that of PS 0. The smoke density of PS 4 is 23.1% lower than that of neat PS. The influence of SiO2 and its nano-hybrids on the pyrolysis and combustion of PS is investigated. Incorporation of SiO2 and its nano-hybrids shows little effect on pyrolysis process of PS. However, heat resistance of PS is enhanced obviously and thermal degradation rate of PS is also decreased through incorporation of SiO2 and its nano-hybrids. The gaseous pyrolysis products (aromatic compounds and alkenyl compounds) of PS and its nanocomposite also decrease.

Numerical Simulation of the Thermal Conversion of Gaseous Products of Polyethylene Pyrolysis

Numerical Simulation of the Thermal Conversion of Gaseous Products of Polyethylene Pyrolysis

Pyrolysis behaviors of antibiotic fermentation residue and wastewater sludge from penicillin production: Kinetics, gaseous products distribution, and nitrogen transformation

Antibiotic fermentation residue (AFR) and wastewater sludge (AFS) were dangerous wastes from penicillin fermentation, and pyrolysis kinetics, gaseous products distribution, and nitrogen transformation of the two were investigated. The content of C/H/N/O/S in AFR was 93.52 %, with good pyrolysis performance and an average activation energy of 230.13 kJ/mol; the content of Fe/O in AFS reached 67.64 %, with poor pyrolysis performance and a high activation energy of 323.77 kJ/mol in the first stage. Monocyclic aromatic hydrocarbons and nitrogenous organics were main gaseous products of AFR pyrolysis, while monocyclic aromatic hydrocarbons and alcohols were main gaseous products of AFS pyrolysis. Pyridine- and pyrrole-nitrogen predominated in the biochar produced by AFR and AFS pyrolysis when the temperature was above 600 °C. The reactions of nitrogen migration and transformation during pyrolysis were summarized. This work provides insights for the pyrolysis potential and the highly concerned nitrogen conversion in AFR and AFS during pyrolysis.

Molten salt pyrolysis of biomass: The evaluation of molten salt

To identify the performance and mechanism of variant molten salts during biomass pyrolysis in molten salt, the thermogravimetric and differential scanning calorimetry (TG-DSC) analyzer, fixed-bed reactor and thermodynamic equilibrium simulation were applied to study the thermal melting characteristics and stability of molten salt as well as the selectivity for biomass pyrolysis products. The KCl-ZnCl2 is appropriate for the preparation of H2-rich gas and the carbon material with abundant mesoporous structure due to its activation effect. At 850 °C, the pyrolysis gas obtained from KCl-ZnCl2 contained 42.22 vol% H2 with the H2/CO ratio reaching 1.69. The carbonates demonstrated excellent improvement for the gas composition of biomass pyrolysis products, with 75.43 vol% and 70.52 vol% syngas (H2 + CO) collected from the Li2CO3-K2CO3 and Li2CO3-Na2CO3-K2CO3 pyrolysis systems at 850 °C respectively. With the presence of carbonates, the bio-oil and char prepared by biomass pyrolysis also achieved better quality. The thermodynamic simulation revealed the shifting (formation of Li2O) of molten salt composition during biomass pyrolysis. The interaction between Li2CO3 and char under high temperature explained the high yield of CO in pyrolysis gas products, also resulted in the consumption of salts and limited the sustainable use of the molten salt pyrolysis system.

Experimental study of ignition behaviors of pyrolysis gas of kerosene‐based endothermic hydrocarbon fuel

The pyrolysis gas consisting of 29.4% CH4, 21.3% C2H4, 30.8% C2H6, and 18.5% C3H6 in mole fraction is presented, as the surrogate of the actual gaseous pyrolysis products. At the conditions of TC = 877.7-963 K, PC = 3.22-4.37 MPa, φ = 0.5 and 1.0, the ignition delays of pyrolysis gas/air (diluted with 52% Ar) have been measured. With TC or PC increasing, the ignition delay time decreases. The auto-ignition of φ = 1.0 is faster than that of φ = 0.5. Furthermore, two widely used small hydrocarbons chemical mechanisms are validated with the measured results. The USC-II mechanism can well predict experimental results at high-T regimes, but fails at low-T regimes. By sensitivity analysis of temperature, the two elementary reactions C2H6 + OH = C2H5 + H2O (negative sensitivity coefficient) and C3H6 + OH = aC3H5 + H2O (positive sensitivity coefficient) have been identified, which have higher reactivity at low-T and lower reactivity at high-T. Considering the extreme uncertainty of rate constants of C3H6 + OH = aC3H5 + H2O, the kinetic parameters have been modified for improving the predictions. The validated results indicate that the optimized mechanism improves predictions of the auto-ignition behavior at low temperature regimes.

Recovery of Carbon Fibre from Waste Prepreg via Microwave Pyrolysis.

Management of waste from carbon fibre composites has become a significant societal issue as the application of composite grows across many industries. In this study, carbon fibres (CF) were successfully recovered from cured carbon fibre/epoxy (CF/EP) prepreg under microwave pyrolysis at 450, 550 and 650 °C followed by oxidation of any residual char. The recovered fibres were investigated for their tensile properties, surface morphologies and the elements/functional groups presented on the surface. The chemical compositions of gaseous and oil pyrolysis products were also analysed. The microwave pyrolysis effectively pyrolyzed the epoxy (EP) resin. Char residue remained on the fibre surface and the amount of char reduced as the pyrolysis temperature increased. Compared to virgin fibres, the recovered fibre suffered from a strength reduction by less than 20%, and this reduction could be mitigated by reducing the pyrolysis temperature. The surface of recovered fibre remained clean and smooth, while the profile of elements and functional groups at the surface were similar to those of virgin fibres. The main gaseous products were CO, H2, CO2 and CH4, whilst the liquid product stream included phenolic and aromatic compounds.

Thermal-catalytic destruction of polyolephin polymers in presence of LnVO3 and LnVO4

This paper describes non-catalytic and catalytic pyrolysis of plastic waste materials. Four types of waste plastics were used in study: high density polyethylene (PE), low density polypropylene (PP), polyethylene terephthalate (PET). Plastic waste was decomposed into three fractions under pyrolysis conditions: gas, liquid and solid residual. The use of vanadates MeVO4 and vanadites MeVO3 of REM (Me=La, Gd, Lu) as catalysts let to change the yield of the gas fraction and change the composition of the gaseous pyrolysis products. Catalytic decomposition increased the amount of the gaseous products by 15–20 %, reduced the condensate, and changed their composition with regard to the non-catalytic process at the same pyrolysis temperature. The total number of reaction products was determined in each fraction. The quantitative analysis of the composition of the gas fraction was performed by gas-liquid chromatography. The study of non-catalytic pyrolysis of plastics and thermogravimetric analysis let to determine the most favorable temperature conditions for the implementation of the catalytic pyrolysis. The catalytic pyrolysis of plastics was carried out in order to obtain the maximum yield of valuable gaseous products. The synthesized vanadites and vanadates of REM were used as catalysts. When using catalysts based on lanthanum and gadolinium compounds, a regular change in the amount of gaseous substances was observed without significant changes in their composition. The use of lutetium vanadate and lutetium vanadite demonstrated a phenomenal result that is associated with the cardinal change of structure of degradation products of PET. The syngas was obtained instead of acetaldehyde. This result is related to the structure of the used catalyst.

A Study on the Law of Gas Production by Pyrolysis of Mixed Insulating Oil under Simulated Overheating Condition

To analyze the law of decomposition and gas production of mixed insulating oil under the action of heat energy, this research conducted the decomposition test of mineral insulating oil, vegetable insulating oil and mixed insulating oil at different hot-spot temperatures through the thermal fault simulation test, compared and analyzed the gas production characteristics and differences of the three insulating oils under the action of heat energy, and analyzed the pyrolysis gas production mechanism of vegetable insulating oil. According to the test results, it can be found that under the condition of no insulating paper and metal catalyst, the characteristic gases produced by the three oils under the action of heat energy are the same, mainly H2, CH4, C2H4, C2H6, CO, CO2. When the temperature is higher than 700°C, a small amount of C2H2 will be produced; when the temperature is low overheated, the pyrolysis characteristic gases of mineral insulating oil are mainly H2 and CH4, while the characteristic gases of vegetable insulating oil and mixed insulating oil are H2 and C2H6; when heated, vegetable insulating oil is more easily to produce H2 than mineral insulating oil; under the same conditions, the CO and CO2 produced in the vegetable insulating oil are much more than that of the mineral insulating oil, dozens of times more at high temperature; the mixed oil presents similar characteristics to the vegetable insulating oil, which is consistent with the relatively large proportion of vegetable oil in the mixed oil.

Butyltriphenylphosphine‐based chelate borates influenced on flame retardancy of polystyrene composite containing self‐expanded intumescent flame retardants

AbstractThe polystyrene (PS) composite containing self‐expanded intumescent flame retardant (polyphosphate ammonium and expandable graphite) was blended with three butyltriphenylphosphine‐based chelate borates, respectively, to evaluate their effect on flame retardancy. The chemical structure of as‐prepared three chelate borates was confirmed by nuclear magnetic resonance (NMR) and Fourier transform infrared spectrum (FTIR). The flame retardancy of various PS composites was evaluated by vertical burning test (UL‐94), limited oxygen index (LOI), and cone calorimeter (CC). Flammability and combustion results suggested that one of chelate borates, named [BTP][BMB], made PS composite (PS4) obtain V‐0 rating, 27.0 ± 0.3% LOI value, and reduction on heat release and smoke production with 17 wt% total flame retardants loading. The combustion residue was analyzed by scanning electron microscope and FTIR, and the pyrolysis gaseous products were investigated by TG‐FTIR technique. Besides, complex viscosity of PS composites composed of various chelate borates from a rheology instrument indicated that the improvements of flame retardancy of PS composites depended on the temperature of construction of crosslinked network by expandable graphite, which the chelate borates showed distinctive influence. Accordingly, the flame‐retarding mechanism about fast response to flame has been proposed.

Facile fabrication of NiAl-LDH and its application in TPU nanocomposites targets for reducing fire hazards

ABSTRACT In this study, nickel-aluminium layered double hydroxide (NiAl-LDH) was prepared and characterised. NiAl-LDH was incorporated into thermoplastic polyurethane (TPU) to prepare a series of TPU/NiAl-LDH nanocomposites using solution mixing technology. Thermogravimetric analysis revealed that the addition of NiAl-LDH increased the thermal stability of TPU/NiAl-LDH nanocomposite at high temperatures. Kinetic analysis of the nanocomposites was conducted via the Coats–Redfern method. Thermogravimetric infrared spectroscopy was carried out to investigate gaseous pyrolysis products in degradation process of TPU/NiAl-LDH nanocomposites. TPU/NiAl-LDH nanocomposites showed a significant decrease in CO, hydrocarbon, and aromatic compound intensities than those of pure TPU, indicating that NiAl-LDH can effectively reduce the fire hazard associated with TPU nanocomposites. Furthermore, X-ray photoelectron spectroscopy, scanning electron microscopy, and Raman spectroscopy were used to analyse char residues of TPU/NiAl-LDH nanocomposites. TPU/NiAl-LDH nanocomposites produced a denser char layer with a significantly enhanced graphitisation degree, which inhibited substance and heat transfer during combustion.

Investigation of pyrolysis kinetics and gaseous compounds emitted during charcoal production from woods commonly used in the Eastern Mediterranean

AbstractAir pollution caused by the traditional charcoal production industry is an environmental problem for developing countries. Avocado (Persea americana) and Lemon (Citrus limon) trees that are commonly used in the charcoal industry in the Eastern Mediterranean were chosen as representatives of charcoal raw material in a wood pyrolysis kinetic study that was conducted using a thermogravimetric analyzer (TGA). The weight loss was measured in a nitrogen atmosphere with a heating rate of 10 °C.min−1 at a temperature range from 30 °C to 700 °C. Four main stages, denoted as dehydration, initial decomposition and both active and final decomposition, were registered in the wood thermal decomposition. The main gases produced were identified in the active decomposition stage for lemonwood and avocado wood, respectively, in the temperature range of 255 to 355 °C and 246 to 340 °C. The released gases in the biomass pyrolysis were measured on‐line using Fourier transform infrared (FTIR) spectroscopy. Main gas products of avocado and lemonwood pyrolysis were similar and included CO2, CO, H2O, CH4, and several organic compounds including methanol, formic acid, acetic acid, and furan. Charcoal production thermogravimetric analysis validated that the wood biomass thermal decomposition process has four stages: (1) water evaporation; (2) initial decomposition; (3) active decomposition, and (4) final decomposition. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd

Relaxation State of Wood and Production of Cellulose Composites for Energy Purposes: Wood Briquettes and Pellets

Changes in the relaxation state of polymeric components of wood at the main stages of production of cellulose composites for energy purposes—wood pellets and briquettes—are considered. The possibility of transition to energy-saving technology due to dispersion under conditions of directional brittle destruction of sawdust during its transformation into a powder material and the extrudability of the powder in subsequent steam humidification is shown. An anomaly of the apparent viscosity of the wood system in the extruder due to the combined effect of water vapor, gaseous pyrolysis products, temperature, and shear stresses is observed.