Co-pyrolysis Process Research Articles

Study on the Effect of n-Hexane Insolubles on Pyrolysis Product Yields Based on Statistical Regression Analysis

Pyrolysis technology has attracted much attention due to its efficient biomass conversion capability, but the significant impact of n-hexane insoluble matter (INS) concentration on pyrolysis product yield has not been fully studied. Therefore, it is of great significance to explore the impact of INS on the yields of tar, water and coke residue. This study developed a linear regression model to analyze the effect of INS concentration on these pyrolysis products. The results show that INS concentration has a significant positive impact on tar yield, but has a smaller impact on water and coke residue yields. In addition, this study constructed a generalized linear model (GLM) to examine the interaction between INS concentration and mixing ratio, and found that the interaction effect was not significant. These findings provide valuable insights into optimizing the co-pyrolysis process of biomass and coal, helping to improve energy conversion efficiency and reduce environmental impact.

Evaluation of char properties from co-pyrolysis of biomass/plastics: effect of different types of plastics

Co-pyrolysis of biomass/plastics is a viable method to obtain high-quality carbon materials. The synergistic effect in the char production process of co-pyrolysis of biomass/plastics affects the properties of the obtained char. However, the synergistic effect research on the char production process of co-pyrolysis of biomass/plastics is facing challenges owing to highly varying composition of different plastics. In this study, the synergistic effect during co-pyrolysis of bamboo (BM) and plastics (polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), polycarbonate (PC), and polybutylene terephthalate (PBT)) was investigated. TG results showed that PP, PS, PET, and PBT promoted the release of biomass volatiles and increased co-pyrolysis char yield. Notably, the O-aromatic structure in PC underwent cleavage and deoxygenation reactions, inhibiting the production of co-pyrolysis char during co-pyrolysis process. Char yield from co-pyrolysis process decreased from 24.80% for bamboo pyrolysis to 15.74% for co-pyrolysis of bamboo/PC. The results of physicochemical tests on char samples indicated that the addition of polyhydrocarbon plastics (PP and PS) increased H/C ratio, O/C ratio, heating value and oxidative reactivity of the char compared to bamboo char due to the vapor deposition of hydrocarbons derived from thermal decomposition of plastics on the biomass char. While, co-pyrolysis of biomass and polyester plastics (PET, PC, PBT) improved the pore structure of char and increased oxygen content.

Facile constructing ZrO2 nanoparticles equipped with high conductivity carbon networks as pseudocapacitive anodes for removing phosphorus

Phosphorus pollution can seriously disrupt water quality and endanger ecosystem sustainability. Nonetheless, a few typical methods have been employed to remove phosphorus, but there are still challenges in controlling phosphorus from sewage. Capacitive deionization (CDI) displays the merits of having eco-friendliness and low energy consumption when capturing phosphorus. However, traditional carbon electrodes often suffer from the limitation that phosphorus uptake sites are insufficient. Herein, a novel ZrO2 nanoparticle equipped with a highly conductive carbon network (NZrC) was fabricated by a facile co-pyrolysis process. Na2EDTA can provide additional carbon backbones, N species, and metal chelation sites. Zr-MOF was applied as the ZrO2 precursor with abundant phosphorus trapping sites. The results suggested that Na2EDTA favors improving the ZrO2 dispersion, mesoporous channel formation, and pseudocapacitive behavior. NZrC-21 at 1.2 V displays low energy consumption and the optimal phosphorus uptake capacity of 10.99 mg P/g because of its rich mesoporous structure, abundant pyrrolic-N, graphitic-N, and ZrO2 active sites, and outstanding electrochemical properties. Furthermore, several key parameters were investigated for their effect on phosphorus removal performance. The mechanism revealed that hydrogen bonds, ligand exchange, and electrostatic attraction are the main uptake processes. This work presents a novel perspective for the facile construction and utilization of metal oxide nanoparticles equipped with a highly conductive carbon network for removing phosphorus.

Elucidating synergistic effects and environmental value enhancement in infrared-Assisted Co-Pyrolysis of coal and polyvinyl chloride

Co-pyrolysis of high-alkali coal and polyvinyl chloride (PVC) through infrared heating is a promising approach for managing escalating PVC waste and converting low-grade coal resources efficiently. The synergistic effects during co-pyrolysis and thermal degradation of PVC were studied through thermogravimetric analysis (TG-FTIR) and spectral analysis. Furthermore, chlorine migration and chemical transformation integral to the process, along with catalytic interactions, were explored through chlorine mass balance assessment, employing X-ray photoelectron spectroscopy and ion chromatography to establish a groundbreaking understanding of these phenomena. The results of products exhibited a trend of initially increasing and then decreasing with increasing temperatures and mixing ratios. The maximum oil yield was 14.62 %, achieving at 600 °C and 20 %. Meanwhile, the content of aromatic hydrocarbons remained high level through the synergistic interaction of Lewis and Brønsted acid sites, nearly exceeding 60 %. The results showed that the Artificial Neural Network model had a high prediction accuracy with an R2 value of 0.99, while the decarboxylation effect dissociated the metal, resulting in an increase in the fixation of inorganic chlorine from 1 % to 66 % and a decrease in the chlorine content in the liquid phase. Innovatively, the study employs an ANN model for predicting the behavior of co-pyrolysis, exemplifying high accuracy in understanding complex thermal conversions of PVC and coal. Notably, the work challenges existing constraints by applying sophisticated analytical methods to elucidate the thermodynamics and kinetics of the co-pyrolysis processes, thereby enhancing the energetic and environmental value of the products.

Exploring the integrated potential of pyrolysis and low-temperature wet torrefaction for typical medical waste valorization: A multifaceted approach leveraging online TG-FTIR-MS, 2D-COS, iso-conversional kinetics, and reaction mechanisms

The rapid growth of medical waste, exacerbated by the COVID-19 pandemic and advancements in healthcare, has drawn increased public scrutiny regarding its proper disposal and treatment. This research aimed to characterize the wet torrefaction of a typical medical waste biomass (MWB) composition, comprising bamboo swabs, skewers, splints, cotton balls, tongue depressors, toothpicks, and chopsticks, followed by its co-pyrolysis with medical waste plastic (MWP) including catheter bags, drapes, IV tubing, IV bags, oxygen masks, syringes, and test tubes. The study employed thermogravimetric analysis, TG-FTIR, 2D correlation spectroscopy, iso-conversional kinetics, and mass spectrometry techniques elucidated the driving factors, behaviors, products, mechanisms, and pathways involved. The pyrolysis temperature ranges were 180.15 to 400 °C for TMWB and 380.04 to 550 °C for MWP, with average activation energies of 150.22 and 221.59 kJ/mol for their respective devolatilization processes. Incorporating 20 % and 40 % MWP into the co-pyrolysis process yielded the best performance, characterized by the lowest activation energy. The co-pyrolysis process promoted the release of cyclic hydrocarbons and chain hydrocarbons, but decreased the yields of alcohols, esters, ethers, phenols, and acids, through synergistic mechanisms. Unraveling the pyrolysis pathways and dynamics of these representative medical waste streams offers valuable insights into improving energy recovery, mitigating pollution, diminishing waste volumes, and optimizing industrial thermochemical conversion processes for safely treating these hazardous materials.

Investigation of the mechanism and interaction of nitrogen conversion during lignin/glutamic acid co-pyrolysis

Biomass pyrolysis has the potential to be transformed into valuable chemicals and fuels. Nitrogenous chemicals exert a substantial influence on the quality of bio-oil. Studying the impact of lignin on the transformation of nitrogen-containing elements in biomass during biomass pyrolysis is crucial for achieving efficient and effective utilization of biomass resources. In this study, tube furnace experiments, thermogravimetric infrared experiments (TG-FTIR), and gas chromatography-mass spectrometry (Py-GC/MS) were used to investigate the interactions of typical lignins (vanillin and syringol), nitrogenous components (glutamic acid), and the effect of lignin on the pyrolysis gas release of glutamic acid and the pyrolysis products during the co-pyrolysis process. In addition, the impact of lignin on the effect of pyrrolidone formation from glutamic acid was investigated in this study in conjunction with quantum chemical calculations. The experimental findings demonstrated that the co-pyrolysis of lignin and glutamic acid resulted in a reduction in the pyrolysis temperature. This reduction facilitated the release of HCN, NH3, and CO2 while notably impeding the formation of nitrogen-containing compounds in the oil. The nitrogen concentration in the pyrolysis oil declined from 97 % to a range of 51.06–79.63 %, and the inhibitory impact decreased as the pyrolysis temperature increased. At an elevated pyrolysis temperature of 800 °C, lignin facilitated the decarboxylation process of glutamic acid, resulting in an increased production of pyrrolidone.Simulation results demonstrated that the lowest energy barrier paths were the dehydration condensation process and the Maillard reaction involving glutamic acid and lignin and their pyrolysis intermediates, with a particular competitive connection between the two pathways. The results explained the interaction mechanism between the two pyrolysis products and provided a fundamental theoretical basis for nitrogen conversion in biomass pyrolysis.

High performance of heterogeneous catalytic ozonation for tetracycline removal by a N-doped biochar derived from co-pyrolysis of sludge and water hyacinth

Enhancing the performance of heterogeneous catalytic ozonation (HCO) for contaminant removal using biochar that is both cost-effective and stable is of great significance. In this research, a novel nitrogen-doped biochar (HSBC) was synthesized through the co-pyrolysis of sludge and water hyacinth. The presence of pyrrolic N, pyridinic N and graphitic N in HSBC as well as the high-temperature co-pyrolysis process, conferred a high degree of graphitization to the biochar. The graphitic N species facilitated the generation of free radicals, while the graphitic structure enhanced electron transfer between the catalyst and tetracycline (TC). HSBC demonstrated exceptional efficiency in TC removal via HCO, achieving a 93% removal rate within just 130 minutes. Moreover, the biodegradability of actual printing and dyeing wastewater with a chemical oxygen demand (COD) of (9900 mg/L) was increased sevenfold after HCO treatment. This study offers new perspectives on the preparation of N-doped biochar and its practical application in the treatment of industrial wastewater through HCO processes.

CO-PROCESSING OF COTTON SOAPSTOCK, COAL DUST AND POLYMER WASTE BY PYROLYSIS METHOD

The work is aimed at solving the problems of rational consumption of secondary raw materials on the basis of carbon-containing waste of industries, saturation of the market with additional products and protection of the environment from the toxic effects of waste. Aim of work: the study of the co-pyrolysis process of gossypol resin (GR) from cotton soapstock of "Shymkentmay" JSC, coal dust (CD) of Kulan deposit and plastics waste (PW) in N2 medium. The methodology of work included the establishment of optimal modes of the process, determination of yield, composition and properties of pyrolysis products. Analysis of pyrolysis products by IR spectroscopy, XRD, chromatomass spectrometry. Study of the component composition of liquid pyrolysis products by the method of extraction separation in Soxhlet apparatus into oils, asphaltenes and resins. Assessment of perspectivity of co- pyrolytic processing of carbon-containing wastes from different industries for industrial development. Results and discussion. The optimum temperature of GR pyrolysis (T=450 ⁰С) was established, at which the yield of liquid product was on average 33.01 wt.%, gas yield – 60.33 wt.%, yield of solid residue – 6.65 wt.%. The co-pyrolysis of GR and CD at 1:1 ratio and T=500 ⁰C in N2 atmosphere was investigated for the first time. A high yield of liquid product – 47.34 wt.%, low gas formation – 2.31 wt.% and a large amount of solid residue – 50.34 wt.% were observed, which is apparently due to the formation of coal semicoke and coke. The process of co- pyrolysis of GR, CD with D=90 μm and PW (PE:HPPP – 1:1) at the ratio of 1:1:1 and temperatures of 500 ⁰С-700 ⁰С in N2 atmosphere was investigated for the first time. It is shown that the main contribution to the formation of liquid products in the given temperature regimes is made by GR and PW. Conclusion. Co-processing of carbon-containing wastes was found to be of interest and practical importance, both in terms of obtaining marketable products and maintaining a safe ecology.

Fast co-pyrolysis of corncob with plastics: Evaluation of thermal behavior using deconvolution procedure, kinetic analysis and product characterization

In this study, the co-pyrolysis of corncob (CC) with polyethylene terephthalate (PET) and polyvinyl chloride (PVC) was first carried out at different blending ratios in a concentrating photothermal TGA (CP-TGA) to gain insights into their thermal behavior, pyrolysis characteristics and kinetic analysis under high heating rate conditions (≥500°C/min). The change in comprehensive pyrolysis index (CPI) for CC/PET and CC/PVC blends was 514 % and 125 %, respectively, when their blending ratio was increased from 25 wt% to 75 wt%. The decomposition rate (Rp %/min) for CC/PET and CC/PVC blends with an increased heating rate showed a favorable co-pyrolysis process. Rapid heating leads to complexity and simultaneous overlapping of the co-pyrolysis components; therefore, the devolatilization phase (active pyrolysis zone) was divided into pseudo-reactions using the Fraser-Suzuki deconvolution function. The deconvolution results of the blend samples fitted well with experimental results (R2 ≥ 0.997). The three pseudo components of CC in the CC25PET75% blend relatively reduced the needed activation energy (E) for PET degradation to about 130 %. With the blending ratio increase, the synergistic activity of pseudo hemicellulose presented trends of an increasing E in CC/PET blends, whereas CC/PVC blends showed decreasing trends. The relative ΔEa deviation revealed that most blend samples would promote an active synergistic reaction. The resultant co-pyrolysis oil from photothermal fixed bed pyrolyzer contained promising bio-renewable platform chemicals such as levoglucosenone, furfural, D-allose, etc. The synergistic interactions between pseudo-lignin and PET contributed to a significant reduction in activation energy and higher selectivity of acetic acid due to the degradation of the ester bonds in PET and the carboxyl groups in lignin. The results of this work could serve as a guide for selecting appropriate reaction parameters for optimal co-pyrolysis synergism.

Synergistic effects and comprehensive analysis of interaction during infrared co-pyrolysis of furfural residues and PVC

Infrared co-pyrolysis was employed to convert waste into valuable resource due to the increasing production of plastic waste. In this study, support vector machine (SVM) accurately predicted PVC and furfural residues thermal behavior. The results showed high accuracy (R2 > 0.95) after the SVM model was trained and validated. Furthermore, this research performed an in-depth characterized of the co-pyrolysis process using various analytical techniques, indicting TG-FTIR-GC/MS, XPS, simulated distillation, and GC/MS. As the temperatures and heating rates increased, the pyrolysis oil yield increased at first and then declined, reaching a maximum of 37.7 % at 600 °C and 10 °C/s. Notably, aromatic content was relatively high, comparing with other components, whereas the chlorinated content remained relatively low, all below 6.5 %, indicating the pyrolysis oil quality had effectively improved. According to the results of XPS, there was a significant 64.11 % increase in inorganic chlorination, which suggested the effective reduction in gaseous chlorine emission and achieving chlorine immobilization.

Study on biomass and polymer catalytic co-pyrolysis product characteristics using machine learning and shapley additive explanations (SHAP)

Biomass and polymer catalytic co-pyrolysis can convert waste into higher-quality fuels, thereby reducing the use of fossil fuels to some extent. However, this process is an extremely complex thermochemical conversion, influenced by numerous factors such as feedstock properties, operational variables, and catalyst. Currently, experimental methods require substantial time and resource investment. Machine learning (ML) can fit and match input and output features based on existing data, achieving extremely high accuracy in the co-pyrolysis process. This study applies advanced ML models to study the biomass and polymer catalytic co-pyrolysis process, with a focus on the yield of pyrolysis products and the variations of the oxygen-containing components in the pyrolysis oil. The best-performing model is used for feature analysis of the correlation between inputs and outputs, based on game theory SHAP analysis. The results indicate a significant negative correlation between the polymer addition ratio and the generation of oxygen-containing components during the co-pyrolysis process. The addition of catalysts promotes the generation of pyrolysis gas during co-pyrolysis but suppresses the yield of pyrolysis oil. Additionally, catalysts significantly inhibit the formation of oxygenates in the pyrolysis oil. The XGBR model shows the highest performance in predicting pyrolysis oil yield, achieving R2 values of 0.98 during training phase and 0.91 during testing phase. The GBR model performs well in predicting the oxygenate composition of pyrolysis oil from small datasets.

Investigation of kinetics, reaction mechanisms, thermodynamics, and synergetic effects in co-pyrolysis of wood sawdust and linear low-density polyethylene using the thermogravimetric approach.

This study focused on investigating thermal degradation behaviors, kinetics, reaction mechanisms, synergistic effects, and thermodynamic parameters of wood sawdust (WSD), linear low-density polyethylene (LLDPE), and their blends (LW1:3, LW1:1, and LW3:1) during co-pyrolysis in a thermogravimetric analyzer (TGA). Thermal behavior exhibited a LW1:3 blend (25 wt.% LLDPE) showing significant mass loss at lower temperatures (150 to 300°C) compared to the individual feedstocks, such as 150 to 400°C and 300 to 520°C for WSD and LLDPE, respectively. The iso-conversional methods (KAS, FWO, and FM) were used to determine the kinetic parameters (Ea and A), and the activation energy drop was highest for the LW1:3 blend. According to the master plots, the third-order reaction (O3), nucleation (P2/3), and diffusional model (D4) were the predominant reaction mechanisms for the co-pyrolysis of the LW1:3, LW1:1, and LW3:1 blend, respectively. The thermodynamic parameters demonstrate that a small amount of plastic addition into WSD can improve the reactivity of the blend, shorten the reaction time, and cause less energy-intensive reactions. The values of ΔH, ΔG, and ΔS also confirmed the co-pyrolysis process's spontaneity and endothermic nature. The Fourier transforms infrared spectrometer (FTIR) spectra of raw feedstock, blends, and their biochar revealed some of the peaks were shifted, the intensity was reduced, and disappearance can happen when the temperature was increased. Using the experimental and theoretical/predicted activation energies, the parity chart illustrates the synergistic effects of co-pyrolysis of different blends, and the LW1:3 blend has a favorable synergistic impact. These results could be helpful in process optimization and designing an effective reactor system for co-pyrolysis.

Research on Biomass & Coal Co-pyrolysis

With the growing global energy demand and the pursuit of renewable energy, biomass and coal co-pyrolysis has attracted much attention as a potential energy conversion technology. In order to optimize energy utilization and increase renewable energy yield, this research systematically analyzed the effects of different biomass and coal combinations on pyrolysis products. The effects of different biomass and coal combinations on the products in the co-pyrolysis process were solved through mathematical modeling. Firstly, the linear regression model shows that INS has a significant positive effect on the yield of tar and coke residue. Then, through the interaction effect analysis, it was found that there was an interaction effect between INS and the mixing ratio. Finally, the optimal INS content and mixing ratio were obtained by optimizing the model, which improved the utilization rate and energy conversion efficiency of the pyrolysis products.

Stepwise dechlorination and co-pyrolysis of poplar wood with dechlorinated polyvinyl chloride: Synergistic effect and products distribution

With the combination of stepwise dechlorination and co-pyrolysis techniques, this study conducted polyvinyl chloride (PVC) dechlorination experiments and co-pyrolysis experiments of poplar wood (PW) with dechlorinated polyvinyl chloride (DPVC) by thermogravimetric analysis and a fixed bed reactor. Stepwise pyrolysis effectively removed Cl from PVC with a dechlorination efficiency of 99.84 % at 360 °C for 30 min. Thermogravimetric tests and thermokinetic variables were employed to describe the co-pyrolysis process's thermodynamic behavior, where co-pyrolysis significantly diminished the activation energy of the initial pyrolysis stage (9.65–21.62 kJ/mol) and increased the reaction rate (0.02–0.09 %/°C). The synergistic effect of co-pyrolysis enhanced the yield and quality of liquid oil and reduced the solid residue rate, with the maximum change in solid residue rate (−2.36 wt%) occurring at PW:DPVC = 3:7. The optimal conditions for the synergistic effect are a raw material ratio of 3:7 at 500 °C. Co-pyrolysis efficiently reduced the content of oxygen-containing compounds of phenols, ketones, and acids in oil, and elevated the selectivity of aromatics. The research methods avoid the drawbacks of bio-oil and plastic oil and improve the quality of pyrolysis oil in a concise and efficient manner, which provides some new ideas for the resource and clean utilization of municipal waste.

Deep insights on the Co-pyrolysis of tea stem and polyethylene terephthalate (PET): Unveiling synergistic effects and detailed kinetic modeling

This study investigates the co-pyrolysis of tea stem (TS) and polyethylene terephthalate (PET), with an emphasis on their interactions during the pyrolysis process. The effects of heating rate and TS/PET ratio on synergy of TS with PET pyrolysis was examined using thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR) techniques. The experimental runs were conducted at three mixing ratios (i.e., 3:1, 1:1, and 1:3) of TS to PET and four heating rates (i.e., 10, 15, 20, and 25 °C/min). The results show that the TS/PET ratio is the main factor determining the synergy of the two components. In particular, the mixture of 25 % TS and 75 % PET exhibited the least antagonistic effects, while the mixture of 75 % TS and 25 % PET had strong synergistic positive and negative effects. Moreover, the FT-IR analysis of the co-pyrolysis process suggested the presence of oxygenated compounds, including hydroxyl and carbonyl groups, indicating the potential formation of aromatic hydrocarbons in the co-pyrolysis process. A new kinetic modeling approach including seven independent parallel reactions (IPR), was developed to illustrate the complex decomposition behavior of the TS-PET mixture. The outcome of kinetic modeling using nonlinear multivariate optimization resulted in a quality of fit ranging from 1.38 % to 3.55 %. These results accurately depict the experimental evidence and offer useful understanding of the reaction kinetics and the overall influence of the mixing ratio on the kinetic triplets.

Natural N/O/S co-doped defect-rich functional carbon materials for aqueous supercapacitors: Effect mechanism of N-containing functional groups on chemical activation

The efficient synthesis of porous carbons with a micro-mesoporous composite structure from low-cost, multi-source biomass was of significant importance for the fabrication of carbon-based supercapacitors. A novel method for the preparation of micro-mesoporous composite carbon materials by co-pyrolysis of multi-source biomass coupled with KOH activation was proposed in this study. The N, O and S co-doped micro-mesoporous composite carbon materials were synthesized using the bamboo and spiral algae as the precursors and KOH as the activator. Spiral algae, as the main source of heteroatoms, played multiple roles (pore forming agent, dopant and enhancer) in the co-pyrolysis process. The enhanced effect of heteroatom doping on KOH activation facilitated the formation of microporous structures. The KCA-500–2 exhibited a porous structure dominated by micropores, with a specific surface area (SSA) of 2421.85 m2/g. At 0.5 A/g, KCA-500–2 displayed an excellent capacitance of 460F/g and outstanding rate performance (73.5 %). The assembled aqueous symmetric supercapacitor (KCA//KCA) demonstrated a maximum energy density of 19.09 Wh/kg at a power density of 150 W/kg. In addition, KCA//KCA attained 97.96 % capacitance retention after 9,000 cycles. This work revealed the synergistic mechanism between N-containing functional groups and KOH activation, suggesting a theoretical guidance for the synthesis of high-performance supercapacitors.

Effective waste management through Co-pyrolysis of EFB and tire waste: Mechanistic and synergism analysis

Driven by the need for solutions to address the global issue of waste accumulation from human activities and industries, this study investigates the thermal behaviors of empty fruit bunch (EFB), tyre waste (TW), and their blends during co-pyrolysis, exploring a potential method to convert waste into useable products. The kinetics mechanism and thermodynamics properties of EFB and TW co-pyrolysis were analysed through thermogravimetric analysis (TGA). The rate of mass loss for the blend of EFB:TW at a 1:3 mass ratio shows an increase of around 20% due to synergism. However, the blend's average activation energy is higher (298.64 kJ/mol) when compared with single feedstock pyrolysis (EFB = 257.29 kJ/mol and TW = 252.92 kJ/mol). The combination of EFB:TW at a 3:1 ratio does not result in synergistic effects on mass loss. However, a lower activation energy is reported, indicating the decomposition process can be initiated at a lower energy requirement. The reaction model that best describes the pyrolysis of EFB, TW and their blends can be categorised into the diffusion and power model categories. An equal mixture of EFB and TW was the preferred combination for co-management because of the synergistic effect, which significantly impacts the co-pyrolysis process. The mass loss rate experiences an inhibitive effect at an earlier stage (320 °C), followed by a promotional impact at the later stage (380 °C). The activation energy needed for a balanced mixture is the least compared to all tested feedstocks, even lower than the pyrolysis of a single feedstock. The study revealed the potential for increasing decomposition rates using lower energy input through the co-pyrolysis of both feedstocks. These findings evidenced that co-pyrolysis is a promising waste management and valorisation pathway to deal with overwhelming waste accumulation. Future works can be conducted at a larger scale to affirm the feasibility of EFB and TW co-management.

Co-pyrolysis of pretreated cotton stalk and low-density polyethylene: Evolved products and pyrolysis mechanism analysis

The preparation of bio-oil from cotton stalks and agricultural residue films using co-pyrolysis technology can achieve resource recovery and energy conversion, which has important research value and significance. In this study, cotton stalks were subjected to different chemical pretreatments using NaOH, HCl, and H2O solutions to understand their structural changes and pyrolysis characteristics. In addition, the lower H/C ratio of cotton stalks resulted in higher oxygen content in the pyrolysis oil, which limited its efficient and clean utilization. Therefore, the characteristics and pyrolysis kinetics of the pyrolysis products of pretreated cotton stalks and LDPE (low-density polyethylene) were studied. The results showed that the ash content of alkali pretreatment cotton stalks decreased by 1.24 %, and the dense structure of cotton stalks significantly relaxed. NaOH pretreatment effectively removed hemicellulose sugars and cracked them. During the co-pyrolysis process, when the ratio of NaOH-CS/LDPE was 50/50, the synergistic effect was more pronounced, and the oil yield increased by 2 % compared to the theoretical value. The oxygen content of CO and CO2 in the pyrolysis gas was higher than the theoretical value, at 10.4 % and 14.1 % respectively. The synergistic effect of bio-oil on hydrocarbons was the most significant, reaching 18.9 %. More hydrogen and less oxygen migrated into the co-pyrolysis oil, resulting in an increase in hydrocarbons and a decrease in oxygen-containing compounds, and improving the quality of bio-oil. Results from electron paramagnetic resonance (EPR) indicated that adding LDPE might raise the quantity of stable free radicals. The evolution mechanism of functional groups of NaOH-CS and LDPE co-pyrolysis behavior was analyzed by Fourier in-situ infrared spectrometry (FTIR), and it was found that C–O–C, C=O, and O–H decreased due to dehydroxylation, decarboxylation, decarbonylation, and demethoxy reactions with the increase of temperature, indicating that there was a synergistic effect between NaOH-CS and LDPE co-pyrolysis. The pyrolysis kinetics of NaOH-CS, LDPE and their blends were determined by the model-free method. The introduction of LDPE can reduce the activation energy of NaOH -CS pyrolysis alone, and the 3D diffusion (D3) model is suitable for their blends.

Synthesis of benzoic acid from catalytic co-pyrolysis of waste wind turbine blades and biomass and their kinetic analysis

This work aims to study the catalytic co-pyrolysis of waste wind turbine blades (WTB: consists of fiberglass/unsaturated polyester resin) and woody biomass (WB) over ZSM-5 and Y-type zeolite catalysts for the production of benzoic acid. The experiments were performed on an equal combination of WTB and WB (WTB/WB) and a fixed amount of catalyst (50 wt%) using a thermogravimetric (TG) analyser at 10, 20 and 30 °C/min. The evolved products from the catalytic co-pyrolysis process were recognized using TG-FTIR and GC/MS. The kinetic and thermodynamic characteristics of catalytic co-pyrolysis was studied using various linear and nonlinear approaches. Also, the decomposition curves were predicted mathematically using an artificial neural network algorithm. The results revealed that the mixture was decomposed in the presence of both catalysts in the form of dual decomposition peaks at 361–374 °C and 428–443 °C, respectively. Based on TG-FTIR results, the CO stretching and carbon dioxide clusters were their main functional groups. While the GC-MS analysis revealed that the released vapours were completely free of toxic styrene (the main compound of resin) and the catalytic co-pyrolysis treatment succeeded in converting it into highly abundant benzoic acid, especially at 10 °C/ min, with an estimated 71.4 % (ZSM-5) and 64 % (Y-type). Whereas the activation energy was estimated at 262–295 kJ/mol (ZSM-5) and 319–357 kJ/mol (Y-type) with almost similar reaction complexity when compared to the case of absence of catalysts. Finally, the developed ANN algorithm showed high efficiency in predicting TG decomposition zones for both WTB/WB mixtures over zeolite catalysts with R2 more than 0.99. These results demonstrate that WB and zeolite catalysts can be used for upgrading the pyrolysis oil of WTB and eliminate its toxic styrene and convert it into benzoic acid and other aromatic hydrocarbons compounds (such as benzene, alanine, and 2-Propanamine).

Co-Pyrolysis of Mushroom Residue Blended with Pine Sawdust/Wheat Straw for Sustainable Utilization of Biomass Wastes: Thermal Characteristics, Kinetic/Thermodynamic Analysis, and Structure Evolution of Co-Pyrolytic Char

Co-pyrolysis technology is considered to be one of the most promising methods for the sustainable utilization of biomass wastes, as it can realize waste reduction and convert wastes into high-value-added products with little impact on the environment. The evaluation of thermal characteristics and product properties is necessary for understanding this technique. In this paper, thermal characteristics and kinetic and thermodynamic analysis during the co-pyrolysis of mushroom residue (MR) with pine sawdust (PS) or wheat straw (WS) were investigated in a TGA. The carbon structure and surface textures of co-pyrolytic char were explored using Raman spectroscopy and a scanning electron microscope. As the PS or WS mass ratio increased, the devolatilization index increased obviously, indicating that volatile release was promoted and concentrated. Weak interactions were observed between 250 and 400 °C during the co-pyrolysis process, which primarily affected the mass transfer, resulting in a change in the thermal decomposition temperatures and rates. The interactions had no prominent influence on the volatiles’ yields. The non-additive performance of average activation energies for the blends was observed due to the interactions, and the lowest average activation energy was obtained when the PS or WS mass ratio was 50%. The lower average pre-exponential factor of the blends indicated the reduced complicacy of the pyrolysis reaction. The relatively small deviation between the activation energy and enthalpy change (4.94–5.18 kJ·mol−1) signified the energy sensitivity of product formation. PS promoted the formation of small aromatic rings (<6 fused rings) in co-pyrolytic chars, whereas WS favored the production of larger rings (≥6 fused rings). The surface textures of the co-pyrolytic chars became porous, and the greater fractal dimensions of the surface morphology for the co-pyrolytic chars indicated that the char surface became irregular and rough.