Pyrolysis Reaction Research Articles

Study on pyrolysis characteristics of gonghe oil shale using Py-GC/MS at different temperatures

ABSTRACT Taking Gonghe oil shale as raw material, rapid pyrolysis experiments were carried out at different temperatures by using Py-GC/MS device to study the effect of different pyrolysis temperatures on the rapid pyrolysis of Gonghe oil shale. The results show that at 420°C, it is more conducive to the precipitation of light hydrocarbons, and the generation of oxygen-containing heterocyclic compounds is the smallest, but it is not conducive to the precipitation of heavy hydrocarbons. At 520°C, not only can it further promote the primary pyrolysis reaction, but it can also reduce the occurrence of secondary pyrolysis reactions, which is more conducive to the rapid pyrolysis of Gonghe oil shale. However, at 470°C, the degree of pyrolysis of Gonghe oil shale is not as good as at 520°C. At 570°C, although it can promote the primary pyrolysis reaction of oil shale, the higher temperature also further promotes the secondary pyrolysis reaction. Therefore, the pyrolysis temperature of 520°C is more conducive to the rapid pyrolysis of Gonghe oil shale.

Pyrolysis kinetics, reaction mechanisms, and thermodynamic parameter analysis of teff straw as a bioenergy potential resource in Ethiopia

Pyrolysis kinetics, reaction mechanisms, and thermodynamic parameter analysis of teff straw as a bioenergy potential resource in Ethiopia

Multi-perspective kinetic analysis of plastic blends under thermogravimetric pyrolysis conditions.

Plastic blends were co-pyrolyzed under non-isothermal conditions in a thermogravimetric (TG) analyzer. The co-pyrolysis characteristics and kinetic triplet, i.e., apparent activation energies, reaction models, and preexponential factors, were investigated from different perspectives, including the overall, weight-loss stage, and overlapping complex reaction deconvolution perspective. Fraser Suzuki (FS) deconvolution was adopted for the peak fitting of the differential TG curves. A model-free method and the master plot theory were used to solve the kinetic equations and fit the reaction mechanism models, respectively. The results indicated that the co-pyrolysis of plastic blends (polyvinyl chloride (PVC)/polypropylene, PVC/polystyrene, PVC/acrylonitrile-butadiene-styrene) could not be adequately described using the overall approach or the weight-loss stage approach. The pyrolysis reaction exhibited a complex multistep overlapping reaction mechanism. FS deconvolution identified and separated four pseudo-reactions from the pyrolysis reaction. The kinetic triplet of the separated reactions was estimated and used to establish kinetic rate equations. Mathematical relations were established between the mass loss rate and pyrolysis temperature. The TG curves of the co-pyrolysis of plastic blends can be parameterized and predicted using the overlapping complex reaction deconvolution model. This study can act as a basis for the development of thermal conversion of mixed plastic waste.

Analysis of the Pyrolysis Kinetics, Reaction Mechanisms, and By-Products of Rice Husk and Rice Straw via TG-FTIR and Py-GC/MS.

This study employed thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) to characterize and provide insights into the pyrolysis behaviors and by-products of rice husk (RH) and rice straw (RS). The primary pyrolysis range is partitioned into three stages, designated as pseudo-hemicellulose, pseudo-cellulose, and pseudo-lignin pyrolysis, by an asymmetric bi-Gaussian function. The average activation energies of the three pseudo-components of RH were estimated by the Flynn-Wall-Ozawa and Starink methods to be 179.1 kJ/mol, 187.4 kJ/mol, and 239.3 kJ/mol, respectively. The corresponding values for RS were 171.8 kJ/mol, 185.8 kJ/mol, and 203.2 kJ/mol. The results of the model-fitting method indicated that the diffusion model is the most appropriate for describing the pseudo-hemicellulose reaction. The reaction of pseudo-cellulose and pseudo-lignin is most accurately described by a nucleation mechanism. An accelerated heating rate resulted in enhanced pyrolysis performance, with RS exhibiting superior performance to that of RH. RH produces 107 condensable pyrolysis by-products, with ketones, acids, and phenols representing the largest proportion; RS produces 135 species, with ketones, phenols, and alcohols as the main condensable by-products. These high-value added by-products have the potential to be utilized in a variety of applications within the agricultural, bioenergy, and chemical industries.

Catalytic decarboxylation of crude oil in a fixed-bed pyrolysis reactor

This study focused on using titanium dioxide (TiO2) as a catalyst to decarboxylate crude oil from the Imo oil field in Nigeria. The TiO2 catalyst was characterised using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). XRD investigation identified rutile-TiO2 as the primary crystalline phase, with important diffraction peaks matching the ASTM standard for rutile. SEM showed extensive agglomerations of TiO2 particles, whereas FT-IR detected surface functional groups such as hydroxyl, carbonyl, and aromatic. TGA identified three separate weight-loss stages, the biggest of which occurred in the devolatilization region, accounting for around 84%. The catalytic decarboxylation process revealed a considerable decrease in the total acid number (TAN) of the crude oil as the temperature increased, reaching a TAN of 0.28 mg KOH g⁻1 at 300 °C, with 96.35% decarboxylation. The TiO2-catalyzed process outperformed thermal cracking alone, resulting in less oxygenated functional groups and increased oil quality. These findings show that rutile-TiO2 can be an excellent catalyst for decarboxylation in crude oil refining.

PIROLIZ REAKTORINING QOVURG‘ALI SIRTI ORQALI ISSIQLIK UZATISH SAMARADORLIGINI HISOBLASH

In this article, the thermal parameters of the biomass pyrolysis thermal processing device were calculated. Also, the flow of flue gas at a temperature of 500-600 ℃ during the pyrolysis process, its movement on the ribbed surfaces of the pyrolysis reactor, and its effect on the water boiler on the outer wall of the reactor were studied. The bioreactor is made of the "pipe in a pipe" type, pyrolysis of biomass takes place in its inner pipe, and water is heated in the outer pipe due to the heat lost to the environment. At the same time, the internal pipe of the reactor allows obtaining gaseous fuel by thermal processing of biomass, and the heat in the external pipe of the boiler solves the problem of providing consumers with hot water in the heating system. The proposed device thermally processes agricultural biomass waste and provides autonomous consumers with alternative fuels and thermal energy at the same time.

Utilization of Syngas as Co-firing Fuel for Carbonization of Arabica Coffee Pulp

Pyrolysis is a commonly used method to produce main products such as bio-char, bio-oil and syngas. However, the practical use of syngas as a fuel is currently constrained by suboptimal properties and the necessity for specialized storage. This study investigated the impact of using syngas directly as an additional fuel for heating the pyrolysis reactor on process parameters and the properties of the resulting bio-char products. The experiment was conducted using two process variations: (i) pyrolysis utilizing syngas as fuel for co-firing with LPG, and (ii) pyrolysis using only LPG as fuel. The variables observed during the testing included the consumption of LPG fuel, process time, heating rate, pyrolysis product yields, and the properties of the bio-char. Characterization of the bio-char was carried out through proximate analysis, bomb calorimetry, thermogravimetric and FTIR analysis. Based on the experimental results it can be concluded that co-firing is able to save on the use of LPG and reduce process time. In terms of product yield, there was no significant difference when syngas was co-fired with LPG. In terms of the properties of the bio-char product, syngas co-firing pyrolysis helps in reducing the moisture content, increasing the fixed carbon content, and also increasing the calorific value up to 26855 J/g.

Particle-resolved simulation of the pyrolysis process of a single plastic particle

Particle-resolved simulations have been performed to study the pyrolysis process of a high-density polyethylene (HDPE) particle in an inert hot nitrogen flow. The simulations resolve the velocity and temperature boundary layers around the particle, as well as the gradients of temperature and concentration within the particle. The objective of this work is to gain an in-depth understanding of the effect of particle morphology-specifically, the particle size and shape-on the interplay between heat transfer and pyrolysis progress, as well as to assess the applicable particle size when using the Lagrangian concept for simulating plastic pyrolysis. In all simulation cases, the pyrolysis reaction is initiated at the external surface of the particle, where the particle is heated the fastest. The reaction front propagates inward toward the core of the particle until it is fully pyrolyzed. For particle diameters larger than 4 mm, distinct temperature gradients within the particle can be detected, leading to a temperature difference of more than 10 K between the core and the external surface of the plastic particle. In this case, the Lagrangian simulations yield a considerably slower conversion compared with the particle-resolved simulations. Moreover, the cylindrical particle in longitudinal flow has been found to be pyrolyzed more slowly compared with the spherical and shell-shaped particles, which is attributed to the enhanced heat transfer conditions for the cylindrical particle. The results reveal the importance of considering particle morphology when modeling plastic pyrolysis. In addition, the Lagrangian approach, which assumes particle homogeneity, is only applicable for particle diameters smaller than 2 mm when modeling plastic pyrolysis.

Time-Dependent Analysis of Catalytic Biomass Pyrolysis in a Continuous Drop Tube Reactor: Evaluating HZSM-5 Stability and Product Evolution

This study investigates a continuous deoxygenation of bio-oil vapor in a catalytic fixed-bed reactor coupled to a continuous drop tube reactor (DTR) for biomass pyrolysis. Beech wood pyrolysis was initially examined without catalysts at various temperatures (500–600 °C). The products were characterised using GC-MS, Karl Fischer titration, GC-FID/TCD, and thermogravimetric analysis. The highest bio-oil yield (58.8 wt.%) was achieved at 500 °C with a 500 mL/min N2 flow rate. Subsequently, ex situ catalytic pyrolysis was performed using an HZSM-5 catalyst in a fixed-bed reactor at a DTR outlet, operating at 425 °C, 450 °C, and 500 °C. The HZSM-5 catalyst exhibited declining deoxygenation efficiency over time, which was evidenced by decreasing conversion rates of chemical families. Principal component analysis was employed to interpret the complex dataset, facilitating a visualisation of the relationships between the experimental conditions and product compositions. This study highlights the challenges of continuous operation as experimental durations were limited to 120 min due to clogging issues. This research contributes to understanding continuous biomass pyrolysis coupled with catalytic deoxygenation, providing insights into the reactor configuration, process parameters, and catalyst performance crucial for developing efficient and sustainable biofuel production processes.

Pyrolysis kinetics and reaction mechanism of waste medical masks by sectional heating process

The COVID-19 epidemic has led to a significant upsurge in the accumulation of waste medical masks. This work focuses on the detailed examination of waste medical masks’ pyrolysis kinetic and reaction mechanism, employing a sectional heating process. The degradation properties were analyzed via thermal gravimetric analysis and pyrolysis reactor. The comprehensive kinetic process was studied using model-free and model-fitting methods, which determined the apparent activation energy and pre-exponential factor. The calculated average value for these parameters was 221.32 kJ/mol and 2.6 × 1014 min−1, respectively. The pyrolysis process was carried out at three distinct temperatures: 380, 470, and 490 ℃, corresponding to the initial peak degradation rate and final degradation temperatures determined by TGA results. The total yield of oil, gas and tar was 88.6 %, 11.3 % and 0.1 %, respectively. The identification and quantification of pyrolysis products were achieved through GC–MS and FTIR. It was observed that higher pyrolysis temperature facilitated the generation of alkanes and hydrocarbons with lower carbon chain lengths in oil products and propylene monomers in gas products. The dominant pyrolysis products in oil under 380 ℃, 470 ℃ and 490 ℃ were C20, C20 and C12 with the yield of 36.17 %, 48.96 % and 43.35 %, respectively. And the corresponding dominant products in gas all were propylene with the yield of 34.74 %, 53.02 % and 54.55 %, respectively. Furthermore, a reaction mechanism was postulated to elucidate the pyrolysis process under varying temperature conditions.

Physiochemical profiling of bioplasticizer derived from Ficus benghalensis leaves for eco-friendly applications

Ficus benghalensis is a tree belonging to the Moraceae family, reaching a height of 20–30 m and featuring branches that spread out widely, along with roots that grow in the air. F. benghalensis leaf cellulose (FBLC) is a type of biodegradable plasticizer with a restricted range of uses. Using pyrolysis and chemical reactions, this research aimed to produce a biodegradable plasticizer from natural sources. Once extracted, microscopic investigations evaluated the plasticizer’s suitability for use in lightweight packaging. The prominent Fourier transform infrared peaks ranging from 644 to 1124 cm−1 indicated the presence of C–Cl and C–F bonds. Additionally, the peak at 1524 cm−1 corresponds to the C–OH stretching in FBLC plasticizer, which is an organic molecule. The thin, downward UV peak indicated the presence of lignin or hemicelluloses. A strong transmission peak was observed at wavelengths of 240 and 366.34 nm. The FBLC plasticizers could be responsible for the size variations seen in the XRD view. The presence of a prominent thermogravimetric analysis (TGA) peak at an angle of 2θ = 28.35° indicated that the plasticizers had a significant enhancement on its crystalline properties. The material exhibits thermal stability up to a temperature of 271 °C. The FBLC plasticizer’s kurtosis (Rku) value ranged from 13.44 to 15.74, with a maximum value of 15.74 generating spikes on the produced surface and a minimum value of 13.44 skewing atomic force microscopy data. Scanning electron microscopy analysis revealed the presence of micro-sized fillers, plasticizers particles, rough surfaces on the fillers, and well-matched rough surfaces. The EDX test confirmed that the FBLC was free from any elemental impurities and showed a high level of purity. The Rq or Rrms value of FBLC surface roughness, measured at 48.28 μm, represented the square root of amplitudes relative to the midline. A significant reduction at 71.76 °C demonstrated the main thermal transition of the biopolymer, also known as the glass transition temperature of FBLC. In summary, the research findings suggested that bioplasticizers are a viable substitute for synthetic chemicals commonly used in the lightweight packaging industry.

Numerical Model of a Heterogeneous Pyrolysis Reactor of Methane

Numerical Model of a Heterogeneous Pyrolysis Reactor of Methane

CFD simulation investigation of size-induced thermophysical characteristics of biomass materials in a fast pyrolysis reactor

CFD simulation investigation of size-induced thermophysical characteristics of biomass materials in a fast pyrolysis reactor

Thermal performance evaluation of a novel solar-driven pyrolysis reactor

Utilizing concentrated radiation from the sun to drive solid waste pyrolysis can address the carbon-emission issue during the heating process. This study proposed a novel directly irradiated solar-driven pyrolysis reactor with a simplified structure, consisting of alumina insulation, quartz glass tubes, and porous ceramics. The reactor's numerical model, considering the radiative heat transfer at short-wavelength radiation and long-wavelength infrared radiation, was developed for its thermal performance evaluation. The effects of operating conditions (gas inlet velocity and lamp power) and porous media structural parameters (pore size and porosity) on the reactor's thermal performance were investigated to guide the practical application of the solar-driven pyrolysis reactor. The present study also found that using SiC as a porous skeleton increased the energy absorption of porous media from 17.8 % to 30.0 % due to the higher absorptivity of SiC compared to Al2O3 for solar radiation. The findings revealed the superior thermal performance of the novel reactor structure proposed in the present study, given that the energy absorbed by the porous media was three times that of the directly irradiated reactor with a conventional structure using SiC porous ceramics. This study might broaden the solar thermal utilization pathway and offer the possibility of commercializing solar-driven pyrolysis.

Preparation of high-value carbon nanotubes from real waste plastic towards the negative carbon technology

The preparation of carbon nanotubes (CNTs) from plastics is of great significance for realizing high value utilization of waste and reducing carbon emission. Here, several kinds of real waste plastics were introduced into catalytic pyrolysis, and the process was also optimized. The results showed that the presence of impurities (e.g., adhesive labels) reduced the initial activation energy of the pyrolysis reaction, and the pyrolysis process was extended and could be divided into two stages. During the catalytic process, impurities play a toxic role on the catalyst at higher temperatures and result in the agglomeration of catalyst particles and a decrease in catalytic activity. Less than 10 wt.% carbon fibers were collected from milk cup waste. However, after experimental optimization, the influence of the impurity component was greatly reduced. The toxic effect of organic impurity volatiles on a catalyst was avoided by employing a segmented catalytic pyrolysis process, which led to an increase in solid carbon content of more than 20 % for express package waste. Simultaneously, more uniform and smoother CNTs can be found in the obtained solid carbon. The process of preparing carbon nanotubes with higher yield and better quality is feasible and has important application prospects in the utilization of waste plastics.

A reduced methane pyrolysis mechanism for above-atmospheric pressure conditions

Methane pyrolysis has recently gained significant attention because of its potential to produce hydrogen without any CO2 emissions. Modeling a methane pyrolysis reactor requires a detailed multi-step reaction mechanism consisting of the full reaction pathway up to soot formation. Several models have been proposed in the literature; however, they have not been validated and calibrated to above-atmospheric pressure conditions. Due to the high number of parameters, adjusting the current models parameter set to high-pressure requires mechanism reduction and optimization. In this work, an existing methane pyrolysis mechanism consisting of 1516 reactions and 325 species was reduced using the directed relation graph with error propagation within a temperature and pressure range of 1000–1400 K and 0.1–4 atm. A skeletal mechanism consisting of 343 reactions and 60 species was obtained; resulting in a reaction and species reduction ratio of 4.4 and 5.3, respectively. The target species concentrations, namely CH4, H2, C2H2, C2H4, C2H6, α-C3H4, p-C3H4, were found to be in good agreement with the original mechanism predictions. Then, the rate parameters of the reduced mechanism were fitted against in-house experimental data in the temperature range of 892–1292 K and at a pressure of 4 atm to extend the model validity to above atmospheric pressures. The optimized model showed significant improvement in capturing the experimental data profiles compared to the reduced model predictions. A carbon element flux transfer was performed to identify the importance of additional pathways under high-pressure in aiding faster methane decomposition. The proposed model can be used for the accurate prediction of methane pyrolysis products at a wide range of temperatures and pressures.

Phenol Concentration in Liquid Smoke Production from Rubberwood by Experiment and Simulation with CFD Modeling

Liquid smoke is produced through condensation resulting from the pyrolysis process of rubberwood, without the presence of oxygen. One of the dominant contents of liquid smoke products is phenol. Therefore, this study aimed to examine the molar concentration of simulated liquid smoke and the comparison between the experimental and simulated molar concentrations. The simulation used Ansys Fluent 19.2, a Computational Fluid Dynamics (CFD) program using the finite volume method in its solution. The several stages in completing Ansys simulation include pre-processing, meshing, processing, and post-processing. The geometry depicted in this study was a 2-dimensional pyrolysis reactor. Assumptions made for the simulation comprised using lignin as raw material, along with specified flowrate, and pyrolysis time. The results showed that based on the reaction mechanism, lignin in the pyrolysis process produced a phenol yield of 4.52%. In the final stage, quantitative data simulation results were obtained in the form of molar concentrations produced from liquid smoke products. The molar concentrations in the simulation during pyrolysis for 1, 2, 3, 4, and 5 hours were 0.00183512, 0.0017854, 0.00170856, 0.0017628, and 0.00166788 kmol/m3, respectively. The experimental molar concentration results also showed the same pattern as the simulation data. At 4 hours of pyrolysis, the molar concentration of phenol increased, resulting in liquid smoke with the best quality. A comparison of liquid smoke molar concentration for the simulation and experiment indicated a minimal difference of 0.005%.

Design and construction of low-cost biomass pyrolysis reactor for research and teaching in universities and colleges

Design and construction of low-cost biomass pyrolysis reactor for research and teaching in universities and colleges

Pyrolysis of açai stems (Euterpe oleracea Mart.) and cocoa husks (Theobroma cacao L.) residues for the generation of added-value products in rural areas

AbstractGenerally, agriculture activities represent the main economic income of rural areas, and during these, huge amounts of biomass are generated. This biomass is considered as garbage due to its high storage cost. However, energy and added-value products can be recovered from biomass. Within this context, açai stems and cocoa husks were collected from different rural areas of Bolivia due to their high importance in the local and international markets as two of the most available products of the country. The preliminary study will contribute in the field of green energy recovery and resource management. Thus, in this study, both residues were tested as renewable feedstocks for the generation of added-value products from pyrolysis at 500 °C for 30 min. Açai stems were found to be more suitable to biochar based with yields up to 49.1% ± 2.4%, but also for biogas production (33.9% ± 2.0%). Cocoa husk was also found to be more suitable for biochar production (38.1% ± 1.7%) but also for bio-oils (33.6% ± 17.6%). Both resulting biochars had basic pH (between 10 and 12) and low density (287.2 kg/m3 and 401.7 kg/m3). Additionally, the lack of heavy metals on the surface makes both biochar products good candidates for soil amendment applications. Furthermore, the bio-oil composition is complex and varied, and products such as Maltol, 2-methyl furane, and D-allose have direct applications in the food industry. Moreover, the presence of phenolic compounds and hydrocarbons with more than five carbons in the structure makes the obtained bio-oils suitable for upgrading processes for biofuel production. Finally, the obtained biogases can be applied for local electricity generation, or to reduce the energy requirements for the pyrolysis reactor. Graphical Abstract

Co-pyrolysis of waste plastics and tires: Influence of interaction on product oil and gas composition

The co-pyrolysis of different waste plastics and tires was carried out to investigate the effect of their interaction during co-pyrolysis on the yield and composition of the product oils and gases. Different types of waste plastics, consisting of high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET), were co-pyrolysed with the waste tires using a fixed bed batch pyrolysis reactor. The main gases produced from the individual plastics and tires were hydrogen, methane, ethane, ethene, propane, propene, butane, and butene, whereas PET produced mainly carbon dioxide and carbon monoxide. GC/MS analysis of the product oil produced from tire pyrolysis were mostly aromatic compounds produced from the rubber components of the tire. For HDPE, LDPE and PP pyrolysis, the oil produced was of mainly aliphatic composition, PS pyrolysis gave a considerable portion of single ring aromatic and polycyclic aromatic compounds and PET formed mainly oxygenated compounds and aromatic compounds. Co-pyrolysis of the plastics and tires resulted in an increase in gas yield above what would be expected from feedstock addition, suggesting interaction between the feedstocks. Also, oil analysis of the co-pyrolysis oils indicated significant shifts in the oil composition. For the mixed tire with HDPE and LDPE, aliphatic compounds were increased above that expected from addition with lower yields of single ring and polycyclic aromatic hydrocarbons. In contrast, mixing tire with PP produced higher yields of aromatic hydrocarbons and lower yield of aliphatic and alicyclic compounds than expected from additive calculation. Mixing tire with PS produced higher than expected single ring aromatic compounds but lower yields of polycyclic aromatic and alicyclic hydrocarbons. For the tire-PET co-pyrolysis, the production of oxygenated compounds was decreased in comparison to the expected additive data.