Study Of Pyrolysis Research Articles

Slow pyrolysis of low-density Poly-Ethylene (LDPE): A batch experiment and thermodynamic analysis

This research investigates the catalytic effect of activated charcoal, MgCO3, and ZSM-5 in a batch-pyrolysis reactor with a Low-Density Poly-Ethylene (LDPE) feedstock on pyro-oil yield. Initially, trials with the ZSM-5 catalyst were conducted at various temperatures ranging from 300 to 600 °C, in which 500 °C temperature offered a higher pyro-oil yield. Further, similar experiments were carried out with activated charcoal and MgCO3 at 500 °C. The qualitative and quantitative analysis of pyro-oil was done using GC/MS, DSC, TGA, and FTIR techniques. In GC/MS and FTIR, the range of hydrocarbon lying in C5 – C35 for aliphatic, aromatic, and phenolic groups. Moreover, the thermal stability of pyro-oil is found to be 350 °C and decreased by 10%–450 °C from TGA studies. The elemental analysis of char (C90.08% H9.82% N0.10%) and gas composition of pyro-gas were also studied. Additionally, thermal calculations were done for mass balance, energy balance, and exergy balance at various temperatures and found to be in good agreement with the input and output parameters. As per findings, the pyrolysis studies at 500 °C with LDPE feedstock and ZSM-5 catalyst showed higher pyro-oil yields than other tested catalysts under similar conditions.

Experimental and modeling study of acetone combustion

The pyrolysis and oxidation of acetone were studied using three complementary experimental setups. Jet-stirred reactor experiments were performed at four equivalence ratios (ϕ = 0.5, 1, 2, and ∞), at pressure of 1.067 bar (800 Torr) and over the temperature range of 700–1200 K for pyrolysis and 600–1150 K for oxidation. The decomposition of acetone starts around 800 K with a conversion rate of 50% obtained around 1000 K in both pyrolysis and oxidation studies. The main stable products detected in both conditions are small hydrocarbons (methane, ethane, and ethylene), with also acetaldehyde, CO and CO2 for oxidation. Oscillation behavior was detected beyond 1000 K under oxidation conditions and the products were followed with on-line mass spectrometry. Ignition delay times were measured using a rapid compression machine at pressures of 20 and 40 bar under non-diluted stoichiometric conditions over the temperature range 850–1100 K. The ignition delay times measured in the present study, combined with shock tube data of literature, exhibit a slight inflexion to the Arrhenius behavior, but no negative temperature coefficient. Laminar burning velocities were measured using a flat flame burner at atmospheric pressure for three fresh gas temperatures: ambient temperature, 358 and 398 K. A detailed kinetic model of the combustion of acetone including 852 species and 3265 reactions was developed. This new kinetic mechanism predicts relatively well the experimental measurements of ignition delay times, the mole fraction of the products in the jet-stirred reactor including oscillations and laminar burning velocities. Related flow rate and sensitivity analysis are also presented providing new insights into the acetone reaction network.

Interconnected pyrolysis and gasification of typical biomass in a novel dual fluidized bed

A novel 50 kg/h dual fluidized bed (DFB) was designed and constructed, and pilot study of interconnected pyrolysis and gasification/activation were conducted. Four typical biomass materials were investigated and compared in DFB system. Pyrolyzer temperature and riser temperature were 480–550 °C and 800–850 °C, respectively. Dolomite were used as bed material, and superheated steam was adopted as the fluidizing gas in pyrolyzer and transport gas in loop seals. Biochars were comprehensively characterized and analyzed, and were potential matrix for carbon-based materials. Biochar from wood sawdust was the best carbon-based material matrix compared to other biochars with the highest adsorption capacities of iodine (397.08 mg/g) and methylene blue (600.15 mg/g). Phenols and benzenes (total content of 63.26–97.36%) were the richest components in all bio-oils. Non-condensable pyrolysis gas from corn cob had the highest heating value (10.14 MJ/Nm3) and largest H2 content (23.91 vol%). The total energy yield was 63.54–84.95%, while energy efficiency was 63.79–82.47%. The carbon fixation ratio was in the range of 38.61–53.27% and the highest carbon fixation ratio was 53.27% from peanut shells. The advantages and feasibility of interconnected pyrolysis and gasification/activation technologies by DFB for biomass utilization and carbon capture were assessed in this pilot study. DFB is a promising technology to achieve carbon negative economy, and deserves more research in the future.

Pyrolysis of Polyolefins into Chemicals Using Low-Cost Natural Zeolites

An experimental study of pyrolysis from polyethylene (PE) and polypropylene (PP) has been done by catalytic method and utilization of low-cost natural zeolite in a semi-batch reactor. A low-cost natural zeolite made from acid-treated zeolite with 1 M HCl solution was denoted as HZ. The prepared HZ catalyst was then carried out under pyrolysis reaction at 350, 400, 450 °C for 60 min. The chemical products composition from this reaction was analyzed using Gas Chromatography-Mass Spectrometry (GC–MS). According to the analysis result, a low-temperature reaction of pyrolysis could produce wax in all variant types of feed. Utilization of HZ catalyst could reduce formation wax while also increasing the yield of oil products after the reaction. Catalytic pyrolysis using HZ for PE and PP plastic feed yields oil products up to 67% and 70%, respectively. The composition of oil products mainly consisted of paraffin, olefin, and alcohol compounds. The temperature optimum for the catalytic reaction could produce the highest paraffin and olefin products at 400 °C. Additionally, utilization of low-cost natural zeolite could improve pyrolysis reaction's performance from PP to produce yield olefin products from 39 to 62%.Graphical Abstract

Process study and CO2 emission reduction analysis of coal liquefaction residue fluidized bed pyrolysis

The direct coal liquefaction process usually produces a liquefaction residue of about 30% of its coal feed. The effective utilization of the coal liquefaction residue (CLR), which contains about 80% organic matter, is of great significance for improving the oil yield of the direct liquefaction process and reducing the amount of pollution emitted from this oil-containing organic solid waste. In this study, the CLR fluidized bed pyrolysis process was studied through a fluidized bed reactor pyrolysis experiment and steady-state thermal analysis. The characteristics of CLR were first analyzed, and then the pyrolysis experiment was conducted in a fluidized bed reactor system. The experiment results show that the oil yield is 34.81% at 540°C for an ash-free feedstock using a fluidized bed pyrolysis reactor. Based on the pyrolysis experimental data and the Aspen Plus software platform, the fluidized bed pyrolysis reactor, fractionation column, coke burner, gasifier, and other equipment were modeled to compare four different process schemes. CLR pyrolysis is an endothermic reaction, and its heat is usually supplied by coke combustion, which produces significant CO2 emissions. Case studies of the pyrolysis process were performed in detail in order to reduce CO2 emissions. Thermal efficiency, carbon efficiency, solid waste discharge, and CO2 emissions of the different schemes were compared, and a flexible fluidized pyrolysis (FFP) process coupled with water electrolysis was proposed. The introduction of green hydrogen and green oxygen to the process can realize near-complete utilization of carbon and hydrogen elements in the CLR and produce high-quality liquid fuels and syngas (for further chemical synthesis), and this new process can achieve almost near-zero CO2 emission in the entire unit. This process principle can also be applied to the CO2 emission reduction of organic solid waste pyrolysis, catalytic fluid cracking, fluid coking, and so on.

Pyrolysis and kinetic study of ethanol and DME inside a shock tube

Pyrolysis and kinetic study of ethanol and DME inside a shock tube

An integrated experimental and numerical study of iron-coke briquettes' pyrolysis and reduction behaviour in an industrial-scale pyrolyser

Iron-coke is a promising raw material for ironmaking blast furnaces for reducing carbon consumption and can be produced by pyrolysers, but the present pyrolysis technologies should be improved to further lower energy consumption and CO2 emission. In this work, an integrated experimental and numerical study is conducted to investigate the pyrolysis and reduction behaviours of iron-coke briquettes in an industrial-scale gas heat carrier pyrolyser. A lab-scale two-stage tubular furnace is first employed to pyrolyze the briquette samples to obtain the recycled gas components. A DEM model is then used to simulate the packing status evolution of ellipsoidal iron-coke briquettes in the pyrolyser chamber. A CFD pyrolysis model is then used to study the pyrolysis and reduction behaviours of coke briquettes and then evaluate the impact of switching the carrier gas from traditional exhaust gas to recycled pyrolysis gas on the pyrolysis and reduction behaviours. The comprehensive in-furnace pyrolysis and reduction phenomena are illustrated. The simulation results also indicate that using the recycled gas as the gas heat carrier is beneficial to the pyrolysis efficiency and progress of ferric oxide reduction, compared to the exhaust gas. This study is useful for gas heat carrier pyrolyser design and optimisation for efficient iron-coke production.

Study of waste rubber catalytic pyrolysis in a rotary kiln reactor with spent fluid-catalytic-cracking catalysts

The low utilization rate of waste rubber has caused serious environmental pollution problems. Catalytic pyrolysis is an effective method for ensuring the resource utilization of waste rubber. However, the high cost and nonrecyclability of the used catalysts complicate the utilization of this method in industrial applications. In this paper, the spent fluid-catalytic-cracking (FCC) catalysts were applied into pyrolysis of waste rubber, aiming to reduce the cost of catalytic pyrolysis of waste rubber. At the same time, the pyrolysis mechanisms of the spent FCC catalysts used in waste rubber were studied. Pyrolysis/catalytic pyrolysis experiments on single-rubber-type unvulcanized rubber, single-rubber-type vulcanized rubber, and tread compounds were performed in a self-developed industrial pilot plant. The experimental results showed that the pyrolysis oil yield of the spent FCC catalysts catalyzed pyrolysis of the waste rubber increased and the content of light aromatics in increased by more than 90 %, indicating that the spent FCC catalysts applied in waste rubber can improve the quality of pyrolysis products, increase production efficiency, and realize the collaborative high-value reuse of waste rubberand spent FCC catalysts.

Mechanism study of tobacco pyrolysis based on the analysis of characteristic products and in-situ identification of functional groups evolution on pyrolytic char

To master the fundamental knowledge of the tobacco thermal degradation process is of great significance for the utilization of tobacco waste. Thermogravimetric analysis coupled with Fourier transform infrared spectrometer was used to analyze the thermal degradation of tobacco lamina and the release behavior of small molecular gas products. Based on the composition and component characteristics of tobacco lamina, the process was divided into four stages to elucidate its thermal degradation mechanism. Tobacco lamina pyrolysis at 200–800 °C was carried out on a microreactor with the products analyzed by gas chromatography-mass spectrometry. On the basis of obtaining variation rule of products belonging to different families of organic compounds with temperature, the evolution properties of products within the same family were summarized. Thereinto, the compositions of nitrogen-containing heterocyclic compounds and hydrocarbons were most affected by temperature. The in-situ infrared of the solid residue during tobacco lamina pyrolysis and the corresponding two-dimensional perturbation correlation infrared spectroscopy were performed to reveal the evolution of functional groups on the surface of the pyrolytic char. The results showed that the dehydration and ring-opening reaction of polysaccharides were earlier than the decomposition of carbonyl containing compounds.

Pyrolysis of low‐rank coal: Thermo‐kinetic analysis and product characterization

AbstractPyrolysis, the primary process accompanying the thermal degradation of coal, is complicated, and understanding this process requires kinetic analysis followed by product characterization. In this context, the present work involves the study of kinetics and thermodynamics of low‐rank Indian coal from thermogravimetric analysis data followed by batch pyrolysis and subsequent analysis of the liquid products. The thermal degradation of the coal sample has been carried out using a thermogravimetric analyzer from ambient temperature to 1350 K at five different heating rates (5, 10, 15, 20, and 25⁰C/min) under N2 atmosphere. The kinetic triplets (E, A, and n) are evaluated using the order‐based model‐fitting method. The result of this work shows that coal pyrolysis satisfies the first‐order kinetics mechanism with an average activation energy of 62.141 kJ/mol and a pre‐exponential factor of 123.835 min–1. Thermodynamic parameters such as average enthalpy change (ΔH), entropy change (ΔS), and free energy change (ΔG) of coal pyrolysis are calculated to be 56.1716 kJ/mol, –225.524 kJ/mol/s, and 1.6212 × 105 kJ/mol, respectively. A Batch pyrolysis study of coal was carried out in a semi‐batch reactor at different temperatures with an optimum oil yield of 18.94 wt% at 450°C. The chemical composition of pyrolytic oil was investigated by the FTIR and GC‐MS analysis confirmed the presence of D‐Limonene as the major constituent in the coal pyrolytic oil.

Combined high-pressure experimental and kinetic modeling study of cyclopentene pyrolysis and its reactions with acetylene

A combined experimental and kinetic modeling study is presented to improve the understanding of the formation of polycyclic aromatic hydrocarbons (PAHs) from neat cyclopentene and cyclopentene/acetylene mixtures. High-pressure experiments are conducted for the first time over a temperature range covering 930–1650 K using a single-pulse shock tube coupled to gas chromatography/gas chromatography-mass spectrometry (GC/GC–MS) techniques. Several updates and inclusions, mainly regarding the reactions involving C5 molecules and radicals, are made in our on-going PAH kinetic model, which shows satisfactory predictive performances for the speciation measurements obtained in the current work and in the literature. On the basis of the experimental observations and modeling analyses, the reaction pathways active during the pyrolysis of cyclopentene are illustrated and the effects of acetylene addition as co-reactant on the PAH chemistry are assessed. In all of the cases investigated, it is noted that the cyclopentadienyl radical largely participate in the formation of mono-aromatic hydrocarbons (benzene and styrene) and PAHs (indene, naphthalene and phenanthrene).

Experimental study of the autothermic pyrolysis in-situ conversion process (ATS) for oil shale recovery

Oil shale has not been applied in large-scale industrialization due to its poor efficiency and high energy extraction cost. The autothermic pyrolysis in situ conversion process (ATS) is an oil shale high-efficiency heating method that uses the residual potential heat after kerogen pyrolysis. In this study, one-dimensional oil shale in situ pyrolysis experimental apparatus is designed to study the feasibility, characteristics, and energy efficiency of ATS. The results show that the ATS of oil shale is successfully triggered at 300 °C. The peak surface of autothermic pyrolysis is steadily advancing, proving the feasibility of the method in laboratory-scale experiments. According to the optical characteristics and chemical composition, ATS can be divided into five typical reaction zones: (a) residue zone, (b) autothermic zone, (c) cracking zone, (d) preheating zone, and (e) virgin zone. Compared with the high-temperature nitrogen in situ conversion process (HNICP), pyrolysis oil obtained from ATS contains more light components. When the oil recovery from ATS reaches 97.1%, the energy efficiency reaches 3.46, which is much higher than that of 0.51 for HNICP. This study shows the advantages and feasibility of ATS experimentally, which can be used for the large-scale commercial development of oil shale.

Experimental and numerical simulation study of typical semi-transparent material pyrolysis with in-depth radiation based on micro and bench scales

With the increasing use of semi-transparent material such as photovoltaic panel and PMMA in our modern life, their cyclic utilization has been paid more attention. Pyrolysis, as the key step for thermal conversion, is studied in our current study. Multiple-scale pyrolysis experiments including micro-scale thermogravimetric experiment and bench-scale fire propagation apparatus experiment are conducted. The numerical simulation is carried out on a modified version of FireFOAM within the OpenFOAM toolbox and the predicted results agree well with experimental data, especially basically reproduce the main pyrolysis temperature range and the highest mass loss rate. By coupling of experiment and numerical simulation, the connection of multiple scales is achieved. Namely, the chemical reaction kinetic parameters are obtained from micro-scale thermogravimetric experiment and then set as simulation input parameters. Bench-scale fire propagation apparatus experiment is used to provide simulation validation data when both chemical reaction kinetics and physical mass/heat transfer are considered. Moreover, in view of the non-negligible transmission of light for semi-transparent material, the in-depth radiation is supplemented in our current simulation and the eventual simulation results further prove its important effect on the pyrolysis, especially the maximum of pyrolysis mass loss rate, pyrolysis duration time, top surface and inside temperature.

On the origin of 3-methyl steroids and diasteranes

The potential origin of 3-methyl steroids is investigated through comparison of their carbon number distributions with those of their desmethyl counterparts using GC-MS and GC-MS-MS analysis of a range of oils and some immature source rock bitumens. There is a close genetic link between desmethyl and 3-methyl steranes, consistent with competition between methylation and hydrogenation at C-3 in the shared steroidal precursors, producing strongly positively correlated carbon number distributions within the two series. The absence (or possibly very low levels) of detectable 3-methyl diasteroids in immature bitumen samples suggests that these compounds are not formed in the free bitumen during diagenesis in amounts capable of explaining their abundance in oils. It is possible that they are produced by a limited degree of rearrangement of steroids after they are bound into kerogen or upon cleavage from kerogen and methylation during catagenesis. Support for this proposition is provided by the previous detection of desmethyl diasterenes in the hydropyrolysate of pre-extracted algal biopolymers, as well as the high diasterane/sterane ratios reported in several studies of hydrous pyrolysis of kerogen. Competition between methylation and hydrogenation during catagenetic formation of diasteranes might explain the lower diasterane/regular sterane ratio observed for 3-methyl compared to desmethyl species.

Thermogravimetric and kinetic analysis of orange peel using isoconversional methods

A kinetic study of pyrolysis of dried orange peel is performed using thermogravimetric analysis (TGA) and differential thermogravimetry (DTG). The degradation kinetics are investigated at 1, 5, 10 & 20 °C/min of heating rates in TGA equipment. The results obtained indicated that the process is parted into four stages. The activation energy is calculated using isoconversional methods like KAS, OFW, and Starink methods. Whereas the pre-exponential factors are calculated using KAS and OFW methods. The activation energy for these models ranges between 28 KJ/mol and 90 KJ/mol and the pre-exponential factors range between 107 min−1 and 1013 min−1. The activation energy versus conversion study shows that the activation energy is increasing with conversion and it is almost same for the proposed three methods.

Pyrolysis of micro- and macroalgae in thermobalance coupled with mass spectrometer

Due to the constant increase of energy demand, new ecological sources of energy are being sought. One of the promising directions is the use of algae biomass from special cultivation or biomass floating on the sea. In order to determine the potential of algae for thermal decomposition, the pyrolysis study in thermobalance coupled with mass spectrometer was carried out at heating rates of 5, 10, 20 °C/min, in the temperature range of 30–900 °C Three types of algae: macroalgae Cladophora glomerata and Fucus vesiculosus, and microalgae Chlorella pyrenoidesa were used in this research. During the deconvolution of the derivative of the thermogravimetric curves, three peaks were assigned to the decomposition of carbohydrates, proteins and lipids. The isoconversional kinetic model used indicated that the pyrolysis process occurred in several reactions. The proposed kinetic model consists of three nth order independent parallel reactions of pseudo-components. The calculated activation energy ranged from 39 to 266 kJ/mol for carbohydrates, 177–181 kJ/mol for proteins, and 110–229 kJ/mol for lipids. The obtained results could be used in the design of 3rd generation biorefineries.

Estudio computacional de la pirólisis rápida de biomasa en un reactor de lecho fluidizado

Biofuels are considered a promising source of renewable energy. Pyrolysis uses heat in an inert atmosphere to break down biomass and produce biofuels like bio-oil (tar) and synthesis gas. This paper presents a computational study of fast biomass pyrolysis in a laboratory fluidized reactor. A laminar flow regime and an Eulerian-Eulerian approach were considered. A comprehensive kinetic model consisting of sixteen irreversible, first-order reactions was coupled with conservation equations of mass, momentum, and energy. The computational model was validated with data reported in the literature. The effect of biomass type and reactor temperature on the thermal decomposition of biomass were analyzed, finding a direct relationship between the content of cellulose and production of tar and similarly between the content of lignin and production of char. Also, the absence of lignin in the biomass dramatically changes the tar and gas compositions. Energy requirements, temperature contours, the composition of the exit gases, and final product yields (tar, char, and gas) are reported.

Numerical study of plastic waste pyrolysis driven by char smoldering

Pyrolysis is a promising process for the valorization of plastic waste (PW). However, traditional pyrolysis processes have high energy consumption. On the other hand, smoldering has been proven as an effective and economic process to treat waste, becoming an attractive application for developing countries. Therefore, a reactor for PW pyrolysis driven by char smoldering was investigated in this study. A proof-of-concept was the development of a multidimensional mathematical model to verify the proposed reactor's feasibility and evaluate its performance. It was found that PW was pyrolyzed stably driven by a self-sustaining char smoldering front. The model suggested that the air inlet velocity and char concentration determined the duration of the PW pyrolysis process and tar and gas yields by regulating the front velocity and the peak temperature. The carrier gas inlet velocity controlled the tar's residence time in the PW pyrolysis chamber and further affected the tar and gas yields.

Catalytic pyrolysis of torrefied olive stone for production of potential petrochemical alternatives

AbstractBench‐scale fluidized bed fast pyrolysis of as‐received and torrefied residual olive stone (OS) was carried out at 500 °C in the presence or absence of a solid acid catalytic bed. Light to mild torrefaction conditions were investigated, with temperatures of 200, 225, and 250 °C, set in a bench‐scale fluidized bed torrefier. Light torrefaction temperatures (200 and 225 °C) did not yield appreciable differences in the thermogravimetric pyrolysis studies, despite notable changes in mass and energy yield resulting from the influence of temperature difference. The mass and energy yields decreased from 91.1 to 74.0% and from 92.0 to 80.9%, respectively, moving from light to mild torrefaction. The higher heating value (HHV) increased linearly with an increase in torrefaction temperature, reaching a maximum of 22.1 MJ/kg at 250 °C, which was 9.7% greater than the as‐received OS sample. A comparison was made between the influence of light and mild torrefaction on subsequent bench‐scale pyrolysis experiments. In particular, the quality of bio‐liquids for torrefaction coupled to fast pyrolysis shifted signifcantly towards the production of higher phenolic and aromatic derivatives that may find applications as potentaila drop‐in alternative hydrocarbons. © 2022 The Authors. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons Ltd.

Should IQOS Emissions Be Considered as Smoke and Harmful to Health? A Review of the Chemical Evidence.

The chemical evidence that IQOS emissions fit the definition of both an aerosol and smoke, and that IQOS and potentially other heated tobacco products (HTPs) pose some harmful health threats from the range of compounds released even at somewhat lower concentrations is reviewed. Further, we address the yields of harmful and potentially harmful compounds (HPHCs), including polycyclic aromatic hydrocarbons (PAHs), and the constituents of IQOS emission that are diagnostic of pyrolysis to provide information on the temperatures reached in IQOS tobacco sticks. The HPHCs present in IQOS emissions are the same as in conventional cigarette smoke (CCs), analogous to emissions from earlier generation of HTPs classed as smoke. However, Philip Morris International (PMI) studies have to some degree underestimated IQOS aerosol HPHC yields, which are a factor of between 3.2 and 3.6 higher when expressed on a tobacco rather than an IQOS stick basis compared to the reference 3R4F cigarette. Further, IQOS emissions contain carbon particles, which fit definition of both aerosol and smoke. Continual reheating of deposited tar in the IQOS device will occur with real-life use, likely leading to generation of even higher concentrations of HPHCs and particulate matter. Despite IQOS not exceeding 350 °C, local hot spots could exist, causing formation of species (phenol/cresols, PAHs). It is recommended that the impact of repeated use to determine the levels of black carbon (insoluble organic matter) in the particulate matter, and the extent to which compounds in IQOS emissions are formed by pyrolysis need to be assessed rigorously. To address whether uneven temperature profiles in heat sticks can lead to potential hot spots that could, for example, lead to PAH formation, it is recommended that pyrolysis studies on tobacco and other constituents of HTPs are required in conjunction with more effort on heating tobacco blends under controlled temperature/time conditions.