Design Of Pyrolysis Reactors Research Articles

Co‐Pyrolytic Recycling of Bakelite and Polymethyl Methacrylate: Kinetic, Synergistic, and Thermodynamic Analysis

AbstractBakelite, a thermosetting plastic, has limited feasibility for thermal recycling processes such as pyrolysis, unlike thermoplastics, due to its inherent tendency to get charred upon heating and difficulty in being converted into valuable fuel and chemical compounds. In this study, the co‐pyrolysis of bakelite and poly methyl methacrylate is explored to improve the thermal degradation and thus recycling feasibility of bakelite by pyrolysis. The kinetics and thermodynamics of the co‐pyrolysis of blended samples are analyzed using different kinetics models. The thermal degradation experiments of the sample are conducted from ambient to 1000 °C at five various heating rates of 5, 10, 20, 30, and 50 °C/min in an inert N2 gas environment. The results showed that adding poly methyl methacrylate to bakelite changes the pyrolytic degradation temperature and weight loss trend. The kinetic analysis reveals that the thermal degradation at 220–345 °C follows an F2.5 order‐based model with an average activation energy of 181 kJ/mol, while the degradation at 345–475 °C follows an F2 order‐based model with an average activation energy of 318 kJ/mol. The enthalpy changes and free energy change associated with thermal degradation exhibit a positive trend while that of entropy change shows a negative trend. With blending the free energy change and entropy change decreased while enthalpy change increased. During batch pyrolysis at 450 °C, the PMMA‐Bakelite blend generates oil (49.17 %), wax (12.36 %), residue (15.36 %), and gas (23.11 %). According to FTIR and GC‐MS analyses, the pyrolytic oil produced by the co‐pyrolysis of the blended sample at 450 °C comprises 32.23 % saturated hydrocarbons (C9–40), 20.97 % unsaturated hydrocarbons (C6–24), and 46.80 % oxygenated material (C5–19). These findings can assist in the optimization of pyrolysis reactor design for the recycling of thermosetting plastics.

CHALLENGES FOR THE DEVELOPMENT OF NUMERICAL MODELS FOR METHANE PYROLYSIS WITH LIQUID METAL REACTORS

Methane pyrolysis is a technology that is being postulated as an option within the Hydrogen economy. Pyrolysis allows gaseous hydrocarbons to be processed without directly emitting CO2, as it is carried out in the absence of oxygen, allowing its integration into the circular economy concept by producing two recoverable elements, such as solid carbon and hydrogen. It is currently classified as a form of turquoise hydrogen generation, as it shares characteristics of green hydrogen, as it does not emit carbon dioxide in the process, and blue hydrogen, as its primary resource is natural gas. There are several technological options to carry out the pyrolysis of natural gas, ranging from direct thermolysis, through the use of catalysts, the use of plasma arcs, or the development of hydrocarbon decomposition in liquid reaction media, such as molten salts or liquid metals. This communication will describe the main remains for the development of pyrolysis reactors with liquid metals, which are currently at Technology Readiness Level around TRL4, in order to advance towards industrially viable and competitive prototypes and demonstrators. That development requires creating numerical models that can be used for the engineering design of pyrolysis reactors. The design tools for this case must be capable of coupling multiphase and multicomponent fluid-mechanical evaluation, which takes into account the evolution of a gaseous phase (natural gas) into a liquid phase (liquid metal) with the formation of solids (carbon). The fluid dynamic calculation runs into the lack of experimental data that allow its validation, which becomes a critical aspect to be able to estimate the chemical kinetics of the reaction itself. This kinetics strongly depends on the residence time of the gas in the medium, and on the temperature. In this communication, those relations between the fluid-mechanical and chemical model that would allow the evaluation of the conversion of natural gas to hydrogen and carbon in the design of the reactor are analyzed. As a result, a series of experiments are proposed to validate these design tools for the pyrolysis process in liquid metal. Keywords: Decarbonization, Hydrogen, Circular economy, Carbon

Effect of different thermoplastics on the thermal degradation behavior, kinetics, and thermodynamics of discarded bakelite.

In this work, the kinetics, thermodynamics, and mechanism for co-pyrolysis of thermoplastic (PP, HDPE, PS, PMMA)blended bakelite (BL) (1:1 by weight) are explored utilizing different kinetics models like model-fitting and KAS model-free method. The thermal degradation experiments of each sample are conducted from ambient to 1000°C temperature at 5, 10, 20, 30, and 50°C/min heating rates in an inert environment. Thermoplastic blended bakelite is degraded in four steps, including two significant weight loss steps. A significant synergetic effect was observed by the addition of thermoplastics, which is reflected in the change in the thermal degradation temperature zone and the weight loss pattern. Among the four thermoplastics blended bakelites, the promotional synergetic effect is more pronounced for PP addition, causing an increase in the degradation of discarded bakelite by 20%, whereas the addition of PS, HDPE, and PMMA enhances the degradation of bakelite by 10%, 8%, and 3% respectively. Again, the activation energy of the thermal degradation of PP blended bakelite is found lowest followed by HDPE blended bakelite, PMMA blended bakelite, and PS blended bakelite. The mechanism of thermal degradation of bakelite changed from F5 to F3, F3, F1, and F2.5 by the addition of PP, HDPE, PS, and PMMA respectively. A significant change in the thermodynamics of the reaction is also found in the addition of thermoplastics. The kinetics, degradation mechanism, and thermodynamics for thermal degradation of the thermoplastic blended bakelite contribute to the optimization of pyrolysis reactor design to increase valuable pyrolytic products.

Synergy, kinetics, and thermodynamics analysis in the valorization of waste bakelite through co-pyrolysis with HDPE

Bakelite, a thermosetting plastic, can't be recycled suitably by pyrolysis as it is charred upon heating with low conversion to useful products. So, it is required to improve the conversion before charring in order to recycle it into valuable products through pyrolysis. Co-pyrolyzing bakelite with high-density polyethylene (HDPE) should improve its conversion before charring and obtaining more useful products. The design of a co-pyrolysis process requires kinetics and thermodynamic parameters. In this context, co-pyrolysis synergy, kinetics, and thermodynamics of HDPE blended Bakelite (1:1 by wt.) are studied by a variety of kinetics models to calculate kinetics triplets and predict a suitable mechanism. The thermal degradation experimental data are taken from ambient to 1000 °C at 5, 10, 20, 30, and 50 °C/min heating rates in an inert atmosphere. The co-pyrolysis synergy is ascertained from the alteration of temperature zone and weight loss pattern in thermal degradation. HDPE blended Bakelite degraded thermally in two stages (215–420 °C and 425–550 °C). The thermal degradation of HDPE blend Bakelite for the first stage (i.e., 215–420 °C) follows the third order (F3)- based model with activation energy 154 kJ/mol while that for the second stage (i.e., 425–550 °C) follows the 1-D diffusion (D1) model with activation energy 355 kJ/mol. The order of the reaction for the first stage is in the range of 0.035–0.352 and that in the second stage is in the range of 0.110–1.048 for different temperatures. The values of change in free energy, change in enthalpy, and change in entropy for the thermal degradation of HDPE blended Bakelite in the first and the second stage is 590.303 kJ/mol, 66.745 kJ/mol, −939.958 × 10-3JK-1mol-1 and 813.062 kJ/mol, 148.574 kJ/mol, - 876.864 × 10-3 JK-1mol-1 respectively. These kinetic and thermodynamic parameters definitely contribute to the optimization of pyrolysis reactor design.

Pyrolysis Decomposition Kinetics of Microcrystalline Cellulose and Curaua Fiber: Insight of Reaction Models by Using Vyazovkin Method

ABSTRACT This paper provides a full understanding of the pyrolysis mechanism of plant biomass (curaua) and cellulose – two materials that involve complex degradation stages. The chemical/physical reactions occurring in the corresponding mass loss stages are described in detail for each material. Multi-step degradation stages are identified by using Vyazovkin and Flynn–Wall–Ozawa methods and the individual contribution are discussed in terms of the chemical and physical steps involved in the process. The determination of multi-stages processes are rapidly determined applying an easy-to-use method as a first approach. We expect that this study helps to develop an understanding of the thermal degradation for future complex materials as well as to establish the initial guesses and to give an insight into the overall biomass decomposition. Final results can help to design of pyrolysis reactor and to develop new kinetic approaches.

Pyrolysis kinetics of new bioenergy feedstock from anaerobic digestate of agro-waste by thermogravimetric analysis

In this study, thermogravimetric and kinetic analysis of digestate from anaerobic co-digestion of dairy manure and dry biomass of Amaranthus retroflexus L. is presented. Thermal decomposition of digestate was studied in the temperature range 40–1000 °C in an inert atmosphere using thermogravimetric and differential scanning calorimetry (TG-DSC) at the heating rates of 5, 10, 15 and 20 °C/min. According to the results of TG/DTG analysis, the thermal decomposition of digestate occurs in three stages: dehydration, devolatilization and decomposition of carbonaceous residue. The devolatilization stage in pyrolysis is a key stage; therefore, it was divided into two steps: I-st step and II-nd step and analyzed in detail. The kinetic parameters were estimated by isoconversion Friedman, OFW (Ozawa-Flynn-Wall) and KAS (Kissinger-Akahira-Sunose) methods and using model-based methods, such as CnB (reaction of n-th order with autocatalysis by product), Bna (expanded Prout-Tompkins equation) and Fn (the reaction of n-th order). For the model-free methods, the average Eα values for the I-st step were 136.3 kJ/mol and for the II-nd step 143.1 kJ/mol. The average Eα values obtained using the CnB, Bna, and Fn models were 105.8 kJ/mol for the I-st step and 145.6 kJ/mol for the II-nd step, i.e. Eα increased by 37.6%. The results of the evaluation of the thermal behavior of digestate from agro-waste indicate a good prospect for the use of biomass as a new bioenergy feedstock. The obtained kinetic parameters are of great importance for the design of pyrolysis reactors.

Characterization and kinetics of thermal decomposition behavior of plum and fig pomace biomass

Redirecting waste biomass back into the economy can reduce their burden on the environment. The use of waste biomass for the production of fuels, value-added materials or natural fillers has significant economic and environmental benefits. Physico-chemical characterization of waste biomass (plum pomace and fig pomace) was done by proximate, elemental, biochemical analysis, FTIR and SEM analysis. The calorific value of both biomasses can be compared with the calorific value of lignite, which rises their potential use as a solid biofuel. The combustion behavior of biomass was investigated by thermal analysis techniques. Based on thermal degradation experiments performed at four heating rates a kinetic analysis of the biomass decomposition process was accomplished.The kinetic study was done using Kissinger method, Ozawa method, Flynn-Wall-Ozawa (FWO) method, Starink method, and Kissinger-Akahira-Sunose (KAS) method. The value of activation energy obtained by different kinetic methods was ∼210 kJ/mol for plum pomace and ∼162 kJ/mol for fig pomace. Estimated activation energy values were used to calculate thermodynamic parameters. In addition to the fact that the obtained results can serve as a useful reference for the design of pyrolysis reactors, this research has ecological significance because it solves the problem of solid waste disposal.

Numerical analysis on a catalytic pyrolysis reactor design for plastic waste upcycling using CFD modelling.

Catalytic pyrolysis technologies are a current trend to address plastic waste upcycling, offering lower energy consumption and higher value products when compared to conventional thermal pyrolysis. In this study, catalytic pyrolysis of HDPE was simulated using computational fluid dynamics (CFD) in order to analyze the physical behaviour of a designed fluidized bed reactor unit on a pilot scale. Dimensionless numbers were used for heat and mass transfer assessment to provide useful insights for the scale-up of this technology. A fluidized bed reactor configuration was selected for its effective heat/mass transfer and compatibility with ZSM-5 catalyst. Calculations were performed on a set of temperatures (300–500 °C) and feed rates (0.5–1 kg m−2 s−1) to determine the best performing conditions. Tradeoffs between conversion, production rate and heat consumption were discussed. The key results of this study indicate that a feed rate of 1 kg m−2 s−1 at 500 °C yields the best gasoline production while consuming the lowest amount of energy per kilogram of product.

Experimental validation of complex mathematical model of screw reactor coupled with particle model describing pyrolysis of lignocellulosic biomass

As in every complex technological process design, pyrolysis reactor design and optimization require a mathematical model of sufficient complexity. Aside from properties of utilized feedstock, reaction temperature and residence time of solid and gaseous phase are the main parameters in pyrolysis reactor design. Screw pyrolysis reactor, also known as auger reactor, is a well-known and studied reactor type suitable for pyrolysis of heterogeneous materials. In this work, a complex mathematical model of a screw pyrolysis reactor coupled with a particle model is proposed. Primary pyrolysis reactions as well as secondary tar cracking reactions were taken into account. In addition, heat and mass transfer inside a solid particle and heat transfer between both phases and the reactor wall were considered. Experimental results obtained at a pyrolyzer temperature of 650, 700 and 750 °C and residence time of solid phase of 7, 9.6 and 15 min were compared with data predicted by the mathematical model. Both, tar and gas yield predicted by the model at 700 and 750 °C showed a good agreement with experimental data at all solid phase residence times. However, the model predicted higher gas production compared to the experimental one at 650 °C. The value of relative deviation of char yield remained under 2% under all pyrolysis conditions. The proposed model can be used for simulation and optimization of industry-scale screw pyrolyzers. However, its validity should be verified on wider operation temperature range.

Kinetic analysis of waste tire pyrolysis with metal oxide and zeolitic catalysts

Research interest in the conversion of waste tire into energy and fuels via pyrolysis process has increased extensively. To optimize pyrolysis reactor design and operating conditions, an understanding of the pyrolysis kinetics of waste tire is of fundamental importance. This study investigated the pyrolysis kinetics of waste tire in three cases (no catalyst, ZSM-5, and MnO2) under different heating rates. The thermogravimetric data showed that there was no apparent difference between the devolatilization processes of waste tire without catalyst and with ZSM-5. The activation energy was obtained by Friedman’s method, Kissinger-Akahira-Sunose (KAS) method and Flynn-Wall-Ozawa (FWO) method. The activation energy of waste tire pyrolysis suggested that MnO2 had a positive influence on the thermal decomposition of waste tire. Under the catalysis of ZSM-5, the pyrolysis of waste tire produced more C1-C4 alkanes and alkenes. While, the monocyclic aromatic compounds in the oil products were also enriched. Whereas, ZSM-5, which has been popularly used in thermal chemical conversions, had little catalytic effect on the decomposition of waste tire.

The Pyrolysis Reactor Design and The Effect of Liquid Smoke from Coconut Shell on Microbial Contamination of Tofu

Liquid smoke is a natural food preservative which can be made of coconut shells through the pyrolysis process. This study aimed to design a pyrolysis reactor and utilize the coconut shell waste to produce liquid smoke as a natural preservative of tofu. 1.5 kg of chopped coconut shell was pyrolyzed at 400C for 5 hours and produced 488 mL of grade 3 liquid smoke with a yield of 34.23%. The liquid smoke was then purified by extraction using ethyl acetate (1: 1 ratio) solvent and 70C temperature for 2 hours. The extract was then distilled at 80C and produced grade 1 liquid smoke. This liquid smoke had an acid content of 12.26% and a phenol content of 0.73%. This liquid smoke was then applied to tofu for 3 days and analyzed the microbial contamination. The smallest amount of microbial contamination was found in the samples of yellow tofu and white tofu coated with liquid smoke and stored in the refrigerator for 1.4 × 105 CFU / mL and 8 × 103 CFU/ml.

A hybrid kinetic and optimization approach for biomass pyrolysis: The hybrid scheme of the isoconversional methods, DAEM, and a parallel-reaction mechanism

Biomass is a renewable source and is considered as an alternative to fossil fuels. Bioenergy can be released from biomass combustion while various bioproducts can be produced through gasification and pyrolysis. Among these three technologies, pyrolysis is more attractive, because multiple types of bioproducts including biogas, bio-oil, and biochar can be generated during the process. On the other hand, due to the convolution of biomass pyrolysis, the design of pyrolysis reactors is very challenging. In this work, a new hybrid kinetic and optimization approach was proposed to facilitate the design and process optimization of pyrolysis reactors. In the hybrid approach, the isoconversional methods were integrated with a parallel-reaction mechanism to provide more detailed description on thermal decomposition of biomass. Duckweed samples were analyzed in a TGA analyzer at three heating rates (10, 20, and 30 °C/min). The data were studied and compared with our proposed hybrid model. In the proposed approach, the isoconversional methods including the Friedman, FWO, and KAS were first applied to gain the values of kinetic parameters. A kinetic model using a parallel reaction mechanism was then developed to predict the thermal decomposition of duckweed. Furthermore, a nonlinear dynamic optimization model was established and coupled with the kinetic model to gain the optimal kinetic parameters for each parallel reaction and achieve good model-fitting. The same hybrid scheme was also employed and coupled with a three pseudo-components DAEM (distributed activation energy model) to predict duckweed pyrolysis. The model calculations of the hybrid models were all well-matched with experimental data that exhibited great potentials of our proposed hybrid scheme for providing detailed description of biomass pyrolysis.

Design of Pyrolysis Reactor for Waste Plastic Recycling

There is an increase in the production and consumption of plastics in day to day life. All plastics are disposed as waste after their usage. The need to intervene through proper disposal and management of waste plastics is very crucial. These call the use of thermal pyrolysis, which is a way of making these wastes to become very useful to us by recycling them to produce fuel oil. In this study, the pyrolysis reactor was design and manufactured for recycling of waste plastic into fuel working by the principle of thermal pyrolysis process. Three experiments are carried out to test the proper function of the reactor. It was found that about 84% of fuel obtained from one kilogram of plastic at temperature of 360°C. The feed stock that was used for the experiment was plastic wastes of polyethylene with different proportion LDPE and HDPE. The method feeding the feedstock to the reactor was by opining the top cover of the reactor for every batch. The reactor was heating externally using furnaces built for the purpose and at the outlet of reactor the condenser is attached to condense the vapors coming out of it. The reactor temperature was controlled by thermocouple sensor fixed inside the reactor and this sensor connected to an external PD controller. A separation procedure of fuel was employed by controlling the internal temperature of the reactor. Three types of fuel obtained from these experiments which are similar to gasoil, kerosene and diesel temperature range from 130°C - 230°C, 230°C -270°C and 230°C and above respectively. The fuel obtained from the experiment tested and characterized in national petroleum supply enterprise laboratory and meet the physical and chemical characteristic of fuels for different applications.

Determination of the activation energy of water hyacinth (Eichornia crassipes) pyrolysis

ABSTRACTThermogravimetric investigation of the thermo-chemical conversion of water hyacinth to bio-fuels was carried out at temperatures between 35 and 915 °C under a nitrogen environment. It envisaged that the operational envelope for bio-oil production from water hyacinth pyrolysis lies between 250 and 550 °C. Kinetic analysis reveals that pyrolytic degradation of water hyacinth to bio-fuels is actually four consecutive reactions of desorption, evaporation, devolatization, and secondary cracking reactions, which takes place at the temperature range of 35 – 95 °C, 95 – 215 °C, 215 – 355 °C, and 355 – 915°C, with activation energies of 34.18, 6.60, 34.48, and 6.92 kJ/mol respectively. The kinetic parameters determined will prove useful in the design of pyrolysis reactors and gasifiers for the biomass.

Modeling for Pyrolysis of Solid Biomass

In comparison to coal, biomass is characterized by a higher content of volatile matter. It is a renewable source of energy which has many advantages from an ecological point of view. Understanding the physical phenomena of pyrolysis and representing them with a mathematical model is the primary step in the design of pyrolysis reactors. In the present study, an existing mathematical model is used to describe the pyrolysis of a single solid particle of biomass. It couples the heat transfer equations with the chemical kinetics equations. A finite difference method is used for solving the heat transfer equation and the two-step pyrolysis kinetics equations. The model equation is solved for a slab particle of equivalent dimension 0.001 m and temperature ranging from 300 to 923 K. An original numerical model for the pyrolysis of wood chips is proposed and relevant equations solved using original program realized in MATLAB.To check the validity of the numerical results, experimental results of pyrolysis of woody biomass in laboratory facility was used. The samples were heated over a range of temperature from 300 to 923 K with three different heating rates of 21, 32 and 55 K/min, and the weight loss was measured. The simulation results as well as the results obtained from thermal decomposition process indicate that the temperature peaks at maximum weight loss rate change with the increase in heating rate. The experimental results showed that the simulation results are in good agreement and can be successfully used to understand the degradation mechanism of solid reaction.

Kinetic triplet of Colombian sawmill wastes using thermogravimetric analysis

The potential of sawmill wastes as a raw material in pyrolysis process is presented in this study. Non-isothermal thermogravimetric analysis (TGA and DTG) and isoconversional methods were employed to determine triplet kinetic (activation energy, reaction model and pre-exponential factor). Through TGA and DTG, the conversion degree is described as a function of temperature for five heating rates (10, 20, 30, 40 and 50o C/min) and four model-free methods (Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), Friedman, and Vyazovkin) with temperatures ranging from 25 to 1000°C were employed. Isoconversional lines were built for every method at different isoconversional degrees α∈[0,1]. The activation energy E was found as a function of α in the interval χII=[0.2,0.7] where each isoconversional methods were in agreement and the estimated error was sufficiently small. Findings show the same activation energy profile independently of the isoconversional method. In particular the total variation of E in χII was as follows: 209.909–228.238 kJ/mol (FWO); 211.235–229.277 kJ/mol (KAS); 223.050–188.512 kJ/mol (Friedman), and 211.449 kJ/mol-229.512 kJ/mol (Vyazovkin). The reaction model of the process in χII matched with a two-dimensional diffusion (D2) by using a master-plot analysis. The calculated and reported parameters are fundamental information for the pyrolysis reactor design using Sawmill wastes as feedstock.

Pyrolysis characteristics, kinetics, and evolved gas determination of chrome-tanned sludge by thermogravimetry–Fourier-transform infrared spectroscopy and pyrolysis gas chromatography-mass spectrometry

The pyrolysis characteristics, kinetics, and evolved gas analysis of chrome-tanned sludge were investigated by thermogravimetry (TG) with Fourier-transform infrared spectroscopy (TG–FTIR) and pyrolysis with gas chromatography and mass spectrometric detection (Py–GC/MS). Friedman, Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) methods were used to calculate kinetic parameters in the kinetic study. The chrome-tanned sludge contained 7600 mg kg−1 Cr in the form of CrOOH and 41,400 mg kg−1 S in the form of S8. The activation energy derived by Friedman method increased from 139.83 to 590.72 kJ mol−1 as the temperature increased from 50 to 500 °C, much higher than those of lignocellulosic biomass and sewage sludge. The TG–FTIR results showed that the main component of the pyrolysis gases was organics that contained alkane groups, and this component reached a maximum at ∼500 °C. The Py–GC/MS results indicated that the diesel-range organics (C10–C28) accounted for more than 65% of the evolved gases; 20%–31% of the evolved gases were C16 and C18, and included mainly palmitic, stearic, and oleic acids. The evolved gases contained high contents of sulfur and nitrogen compounds, mainly in the forms of elemental sulfur (S6 and S8) and nitriles, respectively. Kinetics and evolved gases determining provide a better understanding of tanned sludge pyrolysis and references for pyrolysis reactor design and scale-up.

Heat transfer characteristics of molten plastics in a vertical falling film reactor

Abstract The heat transfer efficiency during the pyrolysis process is a key factor to be considered in the design of pyrolysis reactors. In this study, the average apparent heat transfer characteristics of molten plastic pyrolysis in a vertical falling film reactor were explored by experiments and numerical simulation and the apparent heat transfer coefficients were determined. In addition, the temperature distribution and the thickness of the liquid film in the reactor were predicted and the influences of pyrolysis temperatures on the average apparent heat transfer coefficients were discussed.

Sustainable recycling of residues from the food waste (FW) composting plant via pyrolysis: Thermal characterization and kinetic studies

Abstract Residues from the food waste (FW) composting factories are an important component of solid waste and commonly treated by landfill and incineration approaches, posing serious environmental and social challenges. In this work, pyrolysis was proposed as a potential alternative method to sustainably recycle FW composting residues as value-added byproducts (bio-char, bio-oil and syngas). To obtain reliable operating and designing parameters for the pyrolytic reactor, the characteristics of the composting residues, the thermal behaviors and kinetic parameters were investigated. The results show that the composting residues mainly consisted of lignin (69%), bone (18%) and plastic (12%), with the lower heat value of around 15.72 MJ/kg. The final pyrolysis temperature of over 500 °C was needed for the complete decomposition of the lignin, bone, and plastic components. According to the comparison between the experimental and calculated thermogravimetric/derivative thermogravimetric curves, only slight interactions were observed in the decomposition of the lignin, bone, and plastic components. The byproducts from lignin/bone pyrolysis might deposit on the plastic material and slightly slow down the mass loss rate. However, the catalytic role of the byproducts were also observed which prompted further investigations. The thermal behavior of the FW composting residues could be successfully modelled by first and third-order chemical reactions respectively in the temperature ranges of 200–360 and 360–510 °C, with activation energy ranging from 25.68 to 41.89 kJ/mol. The results from this study have not only proved the feasibility of the proposed pyrolysis technique for diverting FW composting residues away from landfilling and incineration for enhancing resource recovery from FW, but also provided basic information for further pyrolysis reactor design and operation.

Pyrolysis mechanism of microalgae Nannochloropsis sp. based on model compounds and their interaction

Pyrolysis is one of important pathways to convert microalgae to liquid biofuels and key components of microalgae have different chemical composition and structure, which provides a barrier for large-scale microalgae-based liquid biofuel application. Microalgae component pyrolysis mechanism should be researched to optimal pyrolysis process parameters. In this study, single pyrolysis and co-pyrolysis of microalgal components (model compounds castor oil, soybean protein and glucose) were conducted to reveal interaction between them by thermogrametric analysis and bio-crude evaluation. Castor oil (model compound of lipid) has higher pyrolysis temperature than other model compounds and has the maximum contribution to bio-crude formation. Bio-crude from soybean protein has higher N-heterocyclic compounds as well as phenols, which could be important aromatic hydrocarbon source during biorefineries and alternative aviation biofuel production. Potential interaction pathways based on model compounds are recommended including further decomposition of Maillard reaction products (MRPs) and surfactant synthesis, which indicate that glucose played an important role on pyrolysis of microalgal protein and lipid components. The results should provide necessary information for microalgae pyrolysis process optimization and large-scale pyrolysis reactor design.