Pyrolysis Products Research Articles

Utilization of Charcoal Obtained from Woody Biomass in Metallurgical Processes Based on Solid–Gas Reactions

The high demand for carbon-based products within pyrometallurgy is placing the industry in an increasingly challenging position to meet stringent requirements. To transition away from fossil carbon carriers, biochar emerges as a sustainable and CO2-neutral alternative, presenting a viable solution without necessitating fundamental adjustments to plant technology, unlike hydrogen as an alternative reducing agent. Prior investigations have underscored the potential of woody biomass pyrolysis products for CO2-neutral metallurgy. Nonetheless, it is imperative to recognize that biochar must meet distinct requirements across various metallurgical processes. This paper conducts a comparative analysis between biochar and petroleum coke using thermogravimetric analyses, surface measurements, reactivity assessments, and scanning electron microscopy. Furthermore, the performance in a furnace for simulating the Waelz process, specifically regarding ZnO reduction, is scrutinized. The results illustrate the optical differences between petroleum coke and biochar and the significantly higher reactivity and specific surface area of biochar. When used in solid–gas reactors, it is observed that due to its high reactivity, biochar reacts more vigorously and carbon is completely consumed. However, during the reduction of ZnO, only minor differences were monitored, making biochar comparable to petroleum coke. Therefore, under certain constraints, biochar can be considered a potential substitute for metallurgical solid–gas reactions.

Numerical analysis of microwave-enhanced oil shale pyrolysis by rotation turntable based on the Arbitrary Lagrangian-Eulerian method

Microwave heating technology has great potential for efficient pyrolysis of oil shale. However, the inhomogeneous heating characteristics of microwave heating can lead to secondary cracking of pyrolysis products, thus reducing the overall oil yield. In order to address this issue, a rotational movement of oil shale under microwave heating has been proposed to obtain a uniform temperature distribution of the oil shale. Then, a new coupled three-dimensional electromagnetic-thermal-chemical-hydraulic model incorporating the Arbitrary Lagrangian-Eulerian (ALE) method was developed to investigate the temperature distribution and pyrolysis characteristics of oil shale under the rotational motion during microwave pyrolysis. The effects of rotational speed, rotational direction, and microwave power on the pyrolysis process of oil shale were explored through this model. The results showed that the introduction of rotational movement effectively addressed the uneven temperature distribution within the oil shale. Compared with the static condition, the rotational condition reduced the secondary reactions of oil products during microwave pyrolysis and increased the oil yield of oil shale to 50.12 %. As the rotation speed increased, the temperature distribution within the oil shale became more uniform, but the total oil yield reached its peak at a moderate speed of 180 s/r. Research on microwave power indicated that rotation increased the maximum usable power and highlighted that reducing the residence time of pyrolysis products within the oil shale was key to increasing oil yield. This study provides a novel approach and numerical simulation method for enhancing the microwave pyrolysis efficiency of oil shale, and the findings of this study are applicable to both the ex-situ and in-situ exploitation of oil shale.

Assessing bioenergy prospects of algal biomass and yard waste using an integrated hydrothermal carbonization and pyrolysis (HTC–PY): A detailed emission–to–ash characterization via diverse hyphenated analytical techniques and modelling strategies

Hydrothermal carbonization (HTC) presents a promising method for converting carbonaceous waste into renewable fuels, facilitating energy recovery. This study focuses on the HTC pretreatment of microalgae (Chlorella sorokiniana) and yard waste, examining their physicochemical structural changes, component migration, and potential for valorization via integrated HTC and pyrolysis processes. HTC notably enhances the carbon content while reducing oxygen and nitrogen levels in these feedstocks, producing a clean solid fuel with high energy density. The study investigates the pyrolytic behavior of hydrochars and their blends using different analytical techniques, kinetic modeling, and fixed–bed reactor experiments. The blends with 90% and 70% of microalgae hydrochar (CSH) exhibited the most significant synergistic effects during co–pyrolysis, evident in its devolatilization behaviors and reduced activation energies. Integrating artificial neural networks and response surface methodology models facilitated optimization of pyrolysis parameters and accurate prediction of bio–oil, biochar, and gas yields. The analytical techniques enabled characterization of pyrolysis products, revealing notable changes in bio–oil and biochar compositions, suggesting potential enhancements. The study comprehensively evaluates the HTC–pyrolysis approach’s potential for converting microalgae and lignocellulosic biomass into eco–friendly biofuels for industrial applications.

Effect of reaction conditions on pyrolysis performance of waste plastics loaded with Ni/ZSM-5 catalyst

Ni/ZSM-5 catalysts were prepared by uniformly loading the active metal Ni to ZSM-5 zeolite using excessive wet impregnation method, and the characterization tests of XRD, SEM, H2-TPR, and NH3-TPD were carried out. For the prepared Ni/ZSM-5 catalyst, the pyrolysis–catalytic reforming of waste plastics for gas production performance was explored under different reaction temperatures, steam-carbon (S/C) ratio, catalyst addition amount, and plastic type. The results showed that the gas production volume and gas quality of pure pyrolysis of HDPE and catalytic pyrolysis of Ni/ZSM-5 were improved with the increase of temperature. Given the thermal economy, the optimal pyrolysis temperature was 700 °C, the catalytic gas production was 900 mL, and the hydrogen concentration was 64.4 %. S/C ratio of 1.5 and plastic: catalyst of 1 was the best reaction condition, under which the gas production was 1020 mL and the hydrogen concentration was 65.1 %, respectively. In addition, an appropriate increase in the amount of steam and the addition of catalysts would greatly optimize the final gas production performance. However, excess steam and catalysts was unfavorable to the gas production of plastic pyrolysis, resulting in a waste of resources. Finally, as for the gas production of four plastics, LDPE had the best pyrolysis gasification effect with gas yield of 1040 mL and hydrogen concentration of 65.7 %. The order of catalytic pyrolysis effect of different plastics was LDPE > HDPE > PP > PS.

Pyrolysis solid product as a sorbent for flue gases mercury capture — Part II: Sorbent utilization

This study explores using solid pyrolysis products from six materials as sorbents to capture mercury from flue gas in an experimental fluidized bed combustor. It investigates the effects of activation methods, adsorption temperature, and Hg0/Hg2+ ratios on mercury removal efficiency. Physical and chemical activations are conducted using steam and NaOH, respectively. Tests are run at 100–160 °C with 5 g of sorbent. Results show 120 °C as optimal, with sorbents losing 0.34 % and 0.39 % efficiency with increasing temperature for lignite and black coal. Specific surface area (up to 641 m2∙g–1) significantly influences cumulative removal efficiency (CRE), reaching 80.8 % for lignite and 73.85 % for black coal. Mercury gas recovery averages 35.5 % and 53.7 % after physical and chemical activations. Lignite sorbents exhibit higher CRE than black coal, indicating greater mercury oxidation in black coal flue gas. This study offers a promising method for char recovery from pyrolysis, suggesting competitive sorbents for industrial use.

Pyrolysis mechanism of a highly branched bio-derived fuel and its blends with aviation kerosene (RP-3)

To address the environmental issues caused by traditional aviation fuels, the use of new alternative jet fuels (AJF) is emerging. C1 fuel, due to its excellent performance, is used as a blended fuel with traditional aviation kerosene. In this study, the pyrolysis pathways of C1 fuel are examined from molecular simulations. Furthermore, C1 fuel is blended with traditional aviation kerosene fuel RP-3 in a 1:4 vol ratio, and the potential coupling effects between two fuels are addressed under both pyrolysis and combustion conditions. In the process of fuel pyrolysis, it is observed that the composition of the fuel has a significant impact on the pyrolysis products. The decomposition process of C1 fuel is mainly dominated by branched-chain alkanes, while the pyrolysis of RP-3 primarily involves β-scission reactions of straight-chain alkanes. By comparing the combustion and pyrolysis processes of fuels, it is found that the combustion of fuel first involves the decomposition of fuel molecules, followed by the oxidation of pyrolysis products. Moreover, it is found that the reaction kinetics of blended fuel can be approximated using the additivity of two neat fuels, indicating a minor chemical coupling. Based on the proportion of C1 and RP-3 in the blended fuel, the mass fractions of key hydrocarbon products, including CH4, C2H2, C2H4, C2H6, C3H6, C4H6, C6H6, and C7H8, can be computed from the simulations of neat fuels. From a molecular perspective, the additivity of the HyChem model in describing the combustion behavior of blended fuels is verified.

Analytical evaluation of the performance of pyrolysis-gasification (Py-Gs) combination within hybrid thermochemical-biological biorefinery

Thermochemical treatments like pyrolysis and gasification, were proposed to circumvent hydrolysis bottleneck of conventional 2nd generation biorefineries. Within this big-picture, the target of this article was to establish the type and amount of bioavailable matter that can be obtained through intermediate pyrolysis of biomass followed by gasification of biochar. To establish the amount of “chemical energy” partitioned among different products’ chemical oxygen demand (COD), which is proportional to higher heating value (HHV) and often utilized for biological systems, was applied for the evaluation of thermochemical conversion of a lignocellulosic feedstock (fir wood). The most abundant product of intermediate pyrolysis was biochar, which retains from 33 % to 40 % of feedstock COD (with temperatures starting from 450 °C). The yield of water-soluble pyrolysis products (WS) slightly increases from 24 % at 450 °C to 27 % at 650 °C, whereas the yield of WI increases considerably with the same temperature. Pyrolysis temperature showed a minor effect on the composition of WS as revealed by GC-MS analysis of main compounds and size exclusion chromatography. Preliminary gasification experiments, performed at 850 °C under CO2 atmosphere, provided gasification rates for different biochars, which was equal to 0.004, 0.005, 0.006 min−1 for biochars obtained at 650, 550, and 450 °C respectively. Syngas obtained from gasification of 450 °C and 550 °C biochar was almost tar-free, whereas gasification of 650 °C biochar yielded a detectable amount of tars (0.4 %). Increasing the gasification temperature to 950 °C sharply increases the gasification rate of biochar obtained at 450 °C, allowing to obtain 55% conversion yield. Within the scope of hybrid thermochemical-biological (HTB) processes, the obtained results show that intermediate pyrolysis, when coupled with subsequent 950 °C CO2 gasification of biochar, can deliver 64% of chemical energy (by COD basis) of the lignocellulosic feedstock as bioavailable constituents, which are defined to syngas and WS based on recent biological studies. Whereas downstream fermentation can process syngas and WS materials in an effective way, such yields could surpass the holocellulose-targeted methods based on hydrolysis.

A lava-inspired design strategy based on combustion characteristics of PFRP for excellent flame retardancy via dual action mechanism at wide temperature range

Although plant fiber reinforced composite (PFRP) with environmental-friendly and biodegradable matches with society development requirements and carbon neutral strategy, the inherent flammability limits application in the engineering field, especially in rail transit and aerospace with strict fire standards. In this work, based on combustion behaviors of PFRP, the flame-retardant strategy inspired by the characteristics of volcanic lava in nature which could flow along rock crevices or valleys and form dense ceramic protective layer with outstanding heat insulation on the surface after cooling is designed. Compared with neat PFRP, the LOI of the PFRP/APP@PTNi20-GP10 (7.7 wt% FR contents) reaches 35.8 %, and UL-94 achieves V-0, showing excellent self-extinguishing performance. Meanwhile, the peak heat release rate (PHRR), total heat release (THR), total smoke release (TSR) and CO production (COP) decrease by 70.1 % and 51.7 %, 60.3 % and 65.5 % respectively. More importantly, the char layer formed after the combustion process retains excellent strength and compactness, which provides better protection for the undecomposed composite. Furthermore, the release of toxic volatiles including aromatic compounds, esters and carbonyl compounds in gas-phase pyrolysis products decrease significantly. The mechanism of lava-inspired flame-retardant system can be attributed to the dual action mechanism where different components play corresponding flame-retardant role under wide temperature range. And it is noted that the designed strategy endows PFRP with excellent fire resistance without deteriorating mechanical properties. This work provides a novel design idea for realizing the flame retardancy of PFRP and broadens the application field of PFRP.

Co-pyrolysis of coal and biomass blends: Impact of pyrolysis temperature and biomass blending on thermal stability of coal, and composition of pyrolysis products

The study investigates the thermal pyrolysis of coal and co-pyrolysis of the coal-sawdust blend (100% blend) in a fixed-bed reactor. The pyrolysis od coal and sawdust was performed at 773 K, 823 K, and 873 K temperature and 30 K min−1 heating rate under nitrogen purge gas (300 mL min−1). Co-pyrolysis coal and biomass was performed at 50%, 100%, and 200% blends at 873 K temperature. The pyrolysis and co-pyrolysis products such as liquid and gas was analysed and compared. Coal pyrolysis resulted higher coal char generation with negligible yield of liquid and gas compared to sawdust. However, 100% co-pyrolyzed blend resulted in higher oil yield % with the increase in temperature from 773 to 873 K with conversion % at 37.35% at 873 K temperature. It was confirmed that the increase in biomass blending percentage with coal, the conversion % increased to 92.8% for the 200% blend. GC/MS characterization of oil from 100% and 200% blended samples revealed that alkane is the main component along with a remarkable Cp value of 1.094 kJ kg−1 K−1 and 0.271 kJ kg−1 K−1 obtained at 823 K and 873 K reaction temperatures respectively. The pyrolysis oil obtained at 873 K at higher biomass to coal blended condition contained higher aromatic compounds. Certain rare comp compounds such as 1-Methyl cyclopropane methanol, 3, 3’- Thiodipropanol, 3- Trans-(1,1-Dimethylethyl)-4, Cis, Methoxycyclohexane-1-ol, 1, 1 -Dimethyl-1-Sinacyclobutane, Octadecane, 2,2,4,15,17,17-Hexamethyl-7, 12-Bis (3, 5,5-Trimethylhexyl), 1,4:3,6-Dianhydro-Alpha-D-Glucopyranose, Hexacosyl acetate and 1,2-Benzenediol, 4-Methyl- present in the copyrolysis oil was also a significant observation in this study.

Review of methods for the reuse and recycling of equine bedding waste

The worldwide expansion of the horse industry has changed the role of horses from work animals to competition, companion and recreation animals. Competition and companion horses spend a significant part of their days confined in stalls, on beds made of different materials, such as shavings. Accumulated waste is removed daily or weekly and is often discarded in an uncontrolled manner, becoming a potential pollutant of soil and water. The present work aims to summarize the potential environmental impact of horse litter disposal practices described in the literature in line with the circular economy. The Science Direct database, the website of the United Nations (UN) and the website of the Brazilian Agricultural Research Corporation (EMBRAPA) were used as source material. The results are displayed using the VOSviewer online software. The main horse litter waste disposal practices were burning (to generate heat), pyrolysis (production of biofuels such as bioethanol and biochar) and production of organic fertilizers. The lowest environmental impact was achieved by a combination of these methods.

Kinetic, products and shrinkage for the pyrolysis of flax fibers

Biomass pyrolysis is a thermochemical process used for renewable products and energies. However, there are still issues that need to be addressed for process modeling and optimization. This study focuses on the relationship between heating rate, shrinkage, and products from flax fibers using thermogravimetric analysis (TGA), microscopic observation, and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). TGA confirms sequential evaporation of water then decomposition of hemicellulose, cellulose, and lignin. Observations from the micro-reactor show that flax fibers undergo shrinkage within the temperature range of 335–370 ∘C, depending on the heating rate. Pyrolysis products were analyzed using Py-GC/MS at four different final temperatures from 350 to 500 ∘C, revealing the presence of anhydrosugars, furans, ketones, phenols, esters, alcohols, aldehydes, and acids. The results indicate a correlation between temperature and the increase in furans and ketones. The analysis suggests that furans and ketones are associated with shrinkage.

Catalytic pyrolysis of wood dust for monophenol over macroalgal biochar-based catalyst: Effects of activation agents and atmospheres during catalyst synthesis on its performance

After introducing heteroatoms into the carbon material skeleton, the performance of carbocatalyst during catalytic pyrolysis of biomass for monophenol production is significantly improved. Algae, as a carbon source with intrinsic nitrogen content, is well-identified as a suitable raw material for preparing heteroatom-doped carbocatalyst. The present study aimed to investigate the effects of different alkaline activation agents (KOH/NaOH) and gas atmospheres (N2/CO2) during the carbonization-activation synthesis process of macroalgal biochar-based catalysts (MBBCs) on their properties and performances. Characterizations of carbocatalysts were carried out via BET and XPS analyses to investigate the porous structures and surface functional groups. Results showed that CO2, as a weakly oxidizing atmosphere, can promote the formation of porous structure of MBBCs. However, the promotion is not as strong as that of chemical activation agents (KOH/NaOH). Furthermore, KOH can promote the formation of porous structure more strongly than NaOH, but NaOH can substantially enhance the formation of surface oxygen‑nitrogen groups compared to KOH. All the MBBCs exhibited the increment of monophenols in the bio-oil obtained from catalytic pyrolysis of wood dust, especially phenol, o-cresol, and p-cresol. Amongst, the biochar-based catalyst activated with NaOH in CO2 atmosphere was the most effective one in promoting monophenols content (up to 59.46 %). Compared with the control group (without catalyst), the phenol content was increased from 5.03 % to 19.40 %. Moreover, it is found that the catalytic performance was positively correlated with the CO species percentage on the surface of MBBCs. The macroalgal biochar-based catalyst has an excellent catalytic performance, which is of great significance for achieving the complete utilization of algae and thereby improving the quality of catalytic pyrolysis products.

Research on the pyrolysis mechanism of tobacco based on low temperature torrefaction

The temperature range of 100–220 °C is known to cause the volatilization of some volatile components and the pyrolysis of some unstable components in tobacco. However, there is a lack of research on the pyrolysis mechanism of tobacco at this temperature range. To address this gap, the present study employed an innovative cascade pyrolysis method based on stepwise heating to analyze the composition of tobacco's rapid pyrolysis products within this temperature range. The analysis was conducted at intervals of 30 °C. The study summarized the release characteristics of organics at different temperatures and analyzed the representative substances of various organic families. In addition, considering that tobacco has a unique composition compared to most biomass, the same five temperature points as they do in the cascade pyrolysis process were selected to torrefy the tobacco samples. These temperatures are lower than the conventional torrefaction temperatures typically used for biomass pretreatment. Multiple techniques were used to systematically analyze the composition, functional group structure, and thermal degradation characteristics of tobacco torrefied at different temperatures. Subsequently, the effect of torrefaction temperature on the release performance of products from tobacco pyrolysis at 650 °C was also studied. The results of this study not only contribute to a more comprehensive understanding of the pyrolysis mechanism of tobacco but also provide theoretical support for cigarette processing and tobacco waste utilization.

Investigation of Pyrolysis Characteristics and Product Evolution Behavior of Methyl Oleate under the Effect of Copper Slag

Investigation of Pyrolysis Characteristics and Product Evolution Behavior of Methyl Oleate under the Effect of Copper Slag

Identification of Main Reaction Path of Soot Formation from Primary Pyrolysis Products in Coal Gasification

Identification of Main Reaction Path of Soot Formation from Primary Pyrolysis Products in Coal Gasification

A hybrid approach combining mechanism-guided data augmentation and machine learning for biomass pyrolysis

Process accuracy modelling requires comprehensive thermodynamics and kinetic knowledge, which is not feasible for complex biomass pyrolysis. Here, we propose a hybrid modelling strategy that combines mechanism-guided modelling (Aspen Plus) with data-driven machine learning (ML) models to accurately predict biomass pyrolysis products. Specifically, we establish the pyrolysis equilibrium model based on the first principles and Gibbs free energy minimization approach; then, the equilibrium model is leveraged to augment data by selecting points with smaller residuals; finally, the augmented data and experimental data serve as input for the ML models training. The results revealed that the hybrid model exhibited superior performance, with average R2 and MAPE values of 0.981 and 0.266, respectively, for predicting biochar yield and heating value. Conclusively, this work introduces new insight and strategy to accelerate the engineered application of bioenergy via modelling biomass pyrolysis and screening biomass.

Utilizing metabolomics and network analysis to explore the effects of artificial production methods on the chemical composition and activity of agarwood.

Introduction: Agarwood is a traditional aromatic southern medicine. It has a long history of being used in traditional Chinese aromatherapy to treat insomnia, anxiety and depression. Due to the scarcity of wild resources, people have planted trees successfully and begun to explore various agarwood-inducing techniques. This study comparative analysis of volatile metabolites in agarwood produced by various inducing techniques and its potential sleep-promoting, anti-anxiety and anti-depressant network pharmacological activities. Methods: A total of 23 batches of two types of agarwood were collected, one of which was produced by artificial techniques, including 6 batches of TongTi (TT) agarwood produced by "Agar-Wit" and 6 batches of HuoLao (HL) agarwood produced by "burning, chisel and drilling", while the other was collected from the wild, including 6 batches of BanTou (BT) agarwood with trunks broken due to natural or man-made factors and 5 batches of ChongLou (CL) agarwood with trunks damaged by moth worms. The study employed metabolomics combined with network analysis to compare the differences in volatile metabolites of agarwood produced by four commonly used inducing techniques, and explored their potential roles and possible action targets in promoting sleep, reducing anxiety, and alleviating depression. Results: A total of 147 volatile metabolites were detected in agarwood samples, mainly including small aromatic hydrocarbons, sesquiterpenes and 2-(2-phenylethyl) chromone and their pyrolysis products. The results showed composition of metabolites was minimally influenced by the agarwood induction method. However, their concentrations exhibited significant variations, with 17 metabolites showing major differences. The two most distinct metabolites were 6-methoxy-2-(2-phenylethyl) chromone and 6,7-dimethoxy-2-(2-phenylethyl) chromone. Among the volatile metabolites, 142 showed promising potential in treating insomnia, anxiety, and depression, implicating various biological and signaling pathways, predominantly ALB and TNF targets. The top three active metabolites identified were 2-(2-phenylethyl) chromone, 1,5-diphenylpent-1-en-3-one, and 6-methoxy-2-[2-(4'-methoxyphenyl) ethyl] chromone, with their relative content in the four types of agarwood being TT>HL>CL>BT. Conclusion: The differences in the content of 2-(2-phenylethyl) chromones suggest that they may be responsible for the varying therapeutic activities observed in different types of agarwood aromatherapy. This study offers theoretical support for the selection of agarwood in aromatherapy practices.

Evaluation of the thermal hazard and pyrolysis mechanism of 1-allyl-3-methylimidazole nitrate and 1-propyl-3-methylimidazole nitrate via thermal analysis and DFT calculation: Effect of structural characteristics

Imidazole ionic liquid, as a green solvent, is one of the most widely used ionic liquids. Understanding its thermal safety characteristics and mechanism is the essential basis for its safe application. In this paper, the thermal hazard characteristics of two ionic liquids with typical structural characteristics are systematically studied, which were 1-allyl-3-methylimidazole nitrate and 1-propyl-3-methylimidazole nitrate ionic liquids. The thermal decomposition peculiarities of two ionic liquids were systematically analyzed by thermogravimetric analyzer, differential scanning calorimetry and accelerating rate calorimeter techniques, and the risk of thermal runaway is also evaluated. In addition, the pyrolysis products and microscopic pyrolysis mechanism of ionic liquids were studied via thermogravimetry-Fourier transform infrared spectroscopy, thermogravimetric mass spectrometry and density functional theory calculation, and the essential mechanism of thermal hazard were determined. The influence of substituent structure on the thermal hazard characteristics of imidazole nitrate ionic liquid was preliminarily analyzed from macroscopic experiment and microscopic mechanism two aspects. This study provides a theoretical basis for the safe application, design and development of imidazole nitrate ionic liquids.

Exploring the potential of cashew nutshells: A critical review of alternative applications

The production of cashew nuts has been increasing globally, leading to a greater volume of waste materials that require proper management. Nevertheless, cashew nutshells (CNS), currently considered waste by most processors, offer a noteworthy opportunity for alternative applications owing to their distinct physical, chemical, and thermal properties. This article reviews alternative applications for CNS that can leverage these properties, while evaluating research gaps. The potential uses are classified into three categories: material development, energy production, and substance absorption. In the materials segment, various examples are discussed where CNS serves as raw material to synthesize biopolymers, cementitious materials, and a broad range of composites. The energy production section discusses various processes that utilize CNS, including pyrolysis, gasification, and briquette production. The absorption section presents CNS and activated carbon derived from CNS as effective absorbents for liquid-phase and gas-phase applications. While this review highlights numerous research-level possibilities for CNS utilization, only a few of these options have been implemented within the industry. Consequently, further research is essential, particularly in CNS characterization, economic and environmental assessment, and real-life implementation, to broaden and enhance the integration of this biomass into applications that can contribute to the value of both its production and processing chain.

ReaxFF reactive molecular dynamic and density functional theory study on the co-pyrolysis mechanism of waste 1,1,1,2-tetrafluoroethane and waste plastics to produce high value-added chemicals and fuels

Pyrolysis is one of the potential way for the degradation of hydrofluorocarbons, but it is difficult to make effective use of the complex pyrolysis products. The addition of plastics can provide sufficient hydrogen source for the degradation of hydrofluorocarbons to generate the high value-added chemicals and fuels. Density functional theory calculation and reactive molecular dynamic simulation are employed to investigate the co-pyrolysis mechanism of 1,1,1,2-tetrafluoroethane and low-density polyethylene in this work. The results show that the H atoms provided by low-density polyethylene promote the defluorination reactions of 1,1,1,2-tetrafluoroethane to generate HF and short chain hydrocarbons, and the number of F atoms in HF molecules accounted for nearly 80 % of the whole reaction system, achieving a better defluorination effect. The defluorination rate of 1,1,1,2-tetrafluoroethane and plastics co-pyrolysis is more than 5 times that of pure 1,1,1,2-tetrafluoroethane pyrolysis. The main co-pyrolysis products of 1,1,1,2-tetrafluoroethane and low-density polyethylene are H2, HF and short chain hydrocarbons, the purpose of hydrofluorocarbons degradation into high value-added chemicals and fuels is realized in this study. This work provides a green, effective way for the conversion waste hydrofluorocarbons and waste plastics into high value-added chemicals and fuels, and achieves the conversion of waste hydrofluorocarbon refrigerants to more economical products.