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A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "A4: Bio-Energy".

Deadline for manuscript submissions: closed (20 April 2022) | Viewed by 28031

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Prof. Dr. Grzegorz Czerski

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Faculty of Energy and Fuels, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow, Poland
Interests: fuels engineering; pyrolysis and gasification; solid fuels conversion; energy efficiency
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Dear Colleagues,

Currently, the use of renewable solid fuels, which include biomass, is of increasing importance. At the same time, the amount and variety of solid waste generated, which should be reused, is growing. Both waste and biomass can be utilized in an efficient and environmentally friendly manner using thermochemical processes such as pyrolysis and gasification. These processes enable the conversion of the mentioned raw materials into useful products, while significantly reducing their negative impact on the environment and the emission of toxic compounds into the atmosphere.

The Special Issue aims to present the results of research on the course of gasification and pyrolysis of biomass and waste, allowing assessment of the raw material used as well as providing information on the mechanism of these processes, intensification and optimization of the gasification and pyrolysis techniques used, and modelling of these processes. Original research articles, as well as review articles, are welcomed.

Prof. Dr. Grzegorz Czerski
Guest Editor

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Keywords

biomass
waste
gasification
pyrolysis

Published Papers (13 papers)

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Editorial

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5 pages, 192 KiB

Open AccessEditorial

Pyrolysis and Gasification of Biomass and Waste

by Grzegorz Czerski

Energies 2022, 15(19), 7299; https://0-doi-org.brum.beds.ac.uk/10.3390/en15197299 - 04 Oct 2022

Viewed by 1331

Abstract

The use of renewable solid fuels, including biomass, is of great importance in today’s society [...] Full article

(This article belongs to the Special Issue Pyrolysis and Gasification of Biomass and Waste)

Research

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18 pages, 2100 KiB

Open AccessEditor’s ChoiceArticle

Development and Comparison of Thermodynamic Equilibrium and Kinetic Approaches for Biomass Pyrolysis Modeling

by Sahar Safarian, Magnus Rydén and Matty Janssen

Energies 2022, 15(11), 3999; https://0-doi-org.brum.beds.ac.uk/10.3390/en15113999 - 29 May 2022

Cited by 16 | Viewed by 2862

Abstract

Biomass pyrolysis is considered as a thermochemical conversion system that is performed under oxygen-depleted conditions. A large body of literature exists in which thermodynamic equilibrium (TE) and kinetic approaches have been applied to predict pyrolysis products. However, the reliability, accuracy and predictive power of both modeling approaches is an area of concern. To address these concerns, in this paper, two new simulation models based on the TE and kinetic approaches are developed using Aspen Plus, to analyze the performance of each approach. Subsequently, the results of two models are compared with modeling and experimental results available in the literature. The comparison shows that, on the one hand, the performance of the TE approach is not satisfactory and cannot be used as an effective way for pyrolysis modeling. On the other hand, the results generated by the new model based on the kinetic approach suggests that this approach is suitable for modeling biomass pyrolysis processes. Calculation of the root mean square error (RMS), to quantify the deviation of the model results from the experiment results, confirms that this kinetic model presents superior agreement with experimental data in comparison with other kinetic models in the literature. The acquired RMS for the developed kinetic method in this paper varies within the span of 1.2 to 3.2 depending on temperature (400–600 °C) and various feedstocks (pine spruce sawdust, bagasse, wood bark, beech wood and paddy straw). Full article

(This article belongs to the Special Issue Pyrolysis and Gasification of Biomass and Waste)

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20 pages, 7641 KiB

Open AccessArticle

The Thermochemical Conversion of Forestry Residues from Silver Fir (Abies alba Mill.) by Torrefaction and Pyrolysis

by Elena Butnaru and Mihai Brebu

Energies 2022, 15(10), 3483; https://doi.org/10.3390/en15103483 - 10 May 2022

Cited by 6 | Viewed by 1402

Abstract

Forestry residue is a renewable energy biomass whose valorization has increased due to the interest in replacing exhaustible and environmentally unfriendly fossil resources. Needles, cones and bark from silver fir were thermally processed by separated and combined torrefaction (250 °C) and pyrolysis (550 °C). The torrefaction removed the humidity and extractives and degraded the hemicelluloses, significantly decreasing the oxygen content to ~11 wt% and increasing the carbon content to ~80 wt%, while enhancing the calorific value of the solids (~32 MJ/kg). The pyrolysis produced solid materials with high amounts of fixed carbon (~60–70 wt%) and high heating values, of ~29 MJ/kg. The combined torrefaction + pyrolysis increased the energy yield of the process and decreased the O/C and H/C atomic ratios to about 0.1 and 0.5, respectively, which is close to those of coals. It also led to condensable products with more homogeneously distributed compounds, regardless of the initial biomass type. More than 110 chemical compounds were confirmed in the condensable products, in amounts that depended on the type of starting material and on the thermal treatment. These included the following: terpenes, from extractives; furans, acids and linear ketones, from hemicelluloses; cyclic ketones and saccharides, from cellulose; and aromatic hydrocarbons and phenol derivatives, from lignin. Clear distinctions between the thermal procedures and the sample origins were evidenced by an exploratory data analysis (PCA), which suggested the presence of different types of lignin in the three starting materials. Full article

(This article belongs to the Special Issue Pyrolysis and Gasification of Biomass and Waste)

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15 pages, 3461 KiB

Open AccessArticle

Application of Slow Pyrolysis to Convert Waste Plastics from a Compost-Reject Stream into Py-Char

by Ewa M. Iwanek (nee Wilczkowska) and Donald W. Kirk

Energies 2022, 15(9), 3072; https://0-doi-org.brum.beds.ac.uk/10.3390/en15093072 - 22 Apr 2022

Cited by 3 | Viewed by 2059

Abstract

There is growing recognition that the degradation of plastics in the environment is a serious problem. This study investigated and reported on the feasibility of removing end-of-life plastics from circulating in the environment. The specific example focuses on non-recyclable plastics found in a waste diversion program for compostable materials, known as the Green Bin Program. The purpose of this study was to identify and quantify the types of polymers in this stream, as well as to determine if it could be successfully turned into char without separation of its components. The measurements show that polyethylene (72 wt.%), polypropylene (14 wt.%) and polyethylene terephthalate (12 wt.%) are the main constituents of this stream, with minor contributions from polybutylene adipate terephthalate (PBAT), polyvinyl alcohol (PVA), poly methyl methacrylate (PMMA), polystyrene (PS), Nitrile rubber and Nylon. Samples of the as-received waste containing plastics and fibrous material were subjected to a slow pyrolysis process. The yield of the char product depended on the conditions of the pyrolysis and a strong synergistic effect was noted when both the plastic and fibrous materials were co-pyrolyzed. The study of variable pyrolysis conditions, along with DTA-TGA-MS studies on the mechanism of the char formation, indicate that the positive effect results from enhanced interaction of plastics with air, in the presence of fibrous material, during the initial/pre-treatment step. Full article

(This article belongs to the Special Issue Pyrolysis and Gasification of Biomass and Waste)

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22 pages, 4140 KiB

Open AccessArticle

Comprehensive Estimation of Combustion Behavior and Thermochemical Structure Evolution of Four Typical Industrial Polymeric Wastes

by Shiqiao Yang, Ming Lei, Min Li, Chao Liu, Beichen Xue and Rui Xiao

Energies 2022, 15(7), 2487; https://0-doi-org.brum.beds.ac.uk/10.3390/en15072487 - 28 Mar 2022

Cited by 3 | Viewed by 1918

Abstract

A huge amount of industrial waste will be generated during the industrialization process and their harmless disposal has always been a headache for reducing carbon emissions. In this study, the combustion behaviors and thermal kinetics of four typical industrial polymeric wastes including rubber, leather, plastic and cloth, were systematically studied by using a Thermogravimetric Analysis. The gas emission and structural evolution was comprehensively analyzed using TG-FTIR, 2D-PCIS, ICP and TEM. The results show that the combustibility of leather and cloth are better than the other two samples, while the rubber and plastic have a wider combustion temperature range for higher content of C-H bonds and, the intermediate oxidation process and the stubborn cracking process of C=C bonds. The surface reaction was considered to be the main reaction of rubber and plastic (pre-exponential factor less than 10⁻⁹), while both leather and cloth went through a complex procedure during multiple decomposition. The volatiles products are gases (e.g., CO₂, CH₄) and small molecules (e.g., H₂O). The high levels of basic metals in the industrial waste causes serious slagging and fouling tendency (fouling index higher than 4.0), which have a serious adverse influence on the operation of a waste incineration plant. Full article

(This article belongs to the Special Issue Pyrolysis and Gasification of Biomass and Waste)

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17 pages, 7683 KiB

Open AccessArticle

Numerical Simulation of the Cleaning Performance of a Venturi Scrubber

by Haouari Khadra, Rahmani Kouider, Naas Toufik Tayeb, Awf Al-Kassir and Juan Pablo Carrasco-Amador

Energies 2022, 15(4), 1531; https://0-doi-org.brum.beds.ac.uk/10.3390/en15041531 - 18 Feb 2022

Cited by 3 | Viewed by 2081

Abstract

Industrial applications need to use different systems for the problem of gas cleaning. A lot of processes have been developed, such as the use of a venturi for gas cleaning and pollution reduction. Additionally, several studies have been developed especially in terms of pressure drop because it is one of the main parameters to determine its efficiency. While the phenomenon of mass transfer in a venturi scrubber has not found much attention, in the present study, a mass transfer two-dimensional simulation is developed for gasification gas cleaning through a venturi scrubber with boundary conditions represented in air inlet velocities of 10, 15, and 20 m/s and water inlet mass flow of 0.02, 0.04 and 0.06 kg/s. In this work, Navier–Stokes equations are solved numerically and the mass transfer technique is treated by the volume of fluid (VOF) model, using CFD software. The obtained results were analyzed by presenting the mass fraction, velocity and pressure contours, and profiles. The probability density function (PDF) of mass transfer is studied too, showing how the removal efficiency of the venturi scrubber increases with a decrease in the liquid flow rate and an increase in the gas velocity. Therefore, the results show that the proposed venturi has the best mass transfer performance with a PDF that reaches 97.6 for velocity liquid of 20 m/s and the removal efficiency showed higher values at low liquid flow rates. Full article

(This article belongs to the Special Issue Pyrolysis and Gasification of Biomass and Waste)

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15 pages, 6108 KiB

Open AccessArticle

Comparison of Pyrolysis and Combustion Processes of Vinyl Floor Panels Using Thermogravimetric Analysis (TG-FTIR) in Terms of the Circular Economy

by Małgorzata Kajda-Szcześniak and Monika Czop

Energies 2022, 15(4), 1516; https://0-doi-org.brum.beds.ac.uk/10.3390/en15041516 - 18 Feb 2022

Cited by 5 | Viewed by 1514

Abstract

The article analyzes the thermal degradation in the inert and oxidative atmosphere of waste vinyl panels, the main component of which is PVC. Both pyrolysis and incineration of plastic waste are difficult, complex and multifaceted processes due to several physical and chemical phenomena occurring during their performance. The coupled TG-MS (thermogravimetry-mass spectrometry) analysis combined with the Fourier transform infrared spectrometry (TG-FTIR) analysis was used to identify the decomposition mechanisms of waste vinyl panels. Thermogravimetric tests were carried out for two heating rates of 5 and 20 K/min in the temperature range of 40–1000 °C, mass losses were determined, and products resulting from thermal degradation were identified. It was found that the individual components decompose at different temperatures depending on the heating rate and the choice of an inert or oxidative atmosphere. Vinyl floor panels were treated in terms of secondary raw material, which, in the light of the circular economy, may constitute a potential energy or chemical resource. Full article

(This article belongs to the Special Issue Pyrolysis and Gasification of Biomass and Waste)

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16 pages, 7063 KiB

Open AccessArticle

The Impact of Torrefaction Temperature on the Physical-Chemical Properties of Residual Exotic Fruit (Avocado, Mango, Lychee) Seeds

by Arkadiusz Dyjakon, Łukasz Sobol, Tomasz Noszczyk and Jakub Mitręga

Energies 2022, 15(2), 612; https://0-doi-org.brum.beds.ac.uk/10.3390/en15020612 - 15 Jan 2022

Cited by 5 | Viewed by 2097

Abstract

A large portion of food loss and waste (FSL) is comprised of seeds and stones. Exotic fruits such as mangoes, lychees and avocados, in which the seeds account for a significant part of the weight and volume of the entire product, are most affected by this problem. The seeds contain a large quantity of polyphenols and essential nutrients, which makes them a good material for extraction. However, conventional extraction techniques are considered time-consuming, and therefore significantly limit their use on an industrial scale. An alternative method of managing the seeds may be their energy utilization. In this study, torrefaction was proposed as a method for the valorization of exotic fruit seeds (mango, lychee, avocado). Thus, the influence of torrefaction temperature (200–300 °C) on the physical-chemical properties of substrates was investigated. The obtained results revealed that, in relation to the unprocessed raw materials, the torreficates are characterized by improved hydrophobic properties (all materials are classified as extremely hydrophobic), higher heating value (at 300 °C the values increased from 17,789 to 24,842 kJ∙kg⁻¹ for mango, from 18,582 to 26,513 kJ∙kg⁻¹ for avocado, and from 18,584 to 25,241 kJ∙kg⁻¹ for lychee), higher fixed carbon content (which changed from 7.87–15.38% to 20.74–32.47%), and significant mass loss, by 50–60%. However, as a side effect of thermal treatment, an increase in ash content (approx. 2–3 times but still less than in coal) was observed. Therefore, the torreficates may be competitive with coal. The possibility of using residues from the food processing sector as a substrate for energy purposes is important from the point of view of environment protection and is a part of the functioning of the circular economy. Full article

(This article belongs to the Special Issue Pyrolysis and Gasification of Biomass and Waste)

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12 pages, 2071 KiB

Open AccessArticle

Effect of Pyrolysis Atmosphere on the Gasification of Waste Tire Char

by Przemysław Grzywacz, Grzegorz Czerski and Wojciech Gańczarczyk

Energies 2022, 15(1), 34; https://0-doi-org.brum.beds.ac.uk/10.3390/en15010034 - 21 Dec 2021

Cited by 7 | Viewed by 2214

Abstract

The aim of the study is to assess the influence of the atmosphere during pyrolysis on the course of CO₂ gasification of a tire waste char. Two approaches were used: the pyrolysis step was carried out in an inert atmosphere of argon (I) or in an atmosphere of carbon dioxide (II). The examinations were carried out in non-isothermal conditions using a Rubotherm DynTherm thermobalance in the temperature range of 20–1100 °C and three heating rates: 5, 10 and 15 K/min. Based on the results of the gasification examinations, the TG (Thermogravimetry) and DTG (Derivative Thermogravimetry) curves were developed and the kinetic parameters were calculated using the KAS (Kissinger-Akahira-Sunose) and FWO (Flynn-Wall-Ozawa) methods. Additionally, the CO₂ gasification of tire chars reaction order (n), was evaluated, and the kinetic parameters were calculated with the use of Coats and Redfern method. Tire waste char obtained in an argon atmosphere was characterized by lower reactivity, which was reflected in shift of conversion and DTG curves to higher temperatures and higher mean values of activation energy. A variability of activation energy values with the progress of the reaction was observed. For char obtained in an argon atmosphere, the activation energy varied in the range of 191.1–277.2 kJ/mol and, for a char obtained in an atmosphere of CO₂, in the range of 148.0–284.8 kJ/mol. The highest activation energy values were observed at the beginning of the gasification process and the lowest for the conversion degree 0.5–0.7. Full article

(This article belongs to the Special Issue Pyrolysis and Gasification of Biomass and Waste)

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15 pages, 2236 KiB

Open AccessArticle

The Effect of Temperature-Pressure Conditions on the RDF Gasification in the Atmosphere of Steam and Carbon Dioxide

by Katarzyna Śpiewak, Grzegorz Czerski and Karol Bijak

Energies 2021, 14(22), 7502; https://0-doi-org.brum.beds.ac.uk/10.3390/en14227502 - 10 Nov 2021

Cited by 5 | Viewed by 1651

Abstract

This research aimed to assess the process conditions, temperature and pressure, on the gasification of alternative refuse-derived fuel (RDF) in the atmosphere of steam and carbon dioxide on a laboratory scale using a fixed bed reactor. For this reason, the selected RDF were analysed, including proximate and ultimate analysis, mercury content and ash composition. After that, isothermal gasification measurements using the thermovolumetric method were performed under various temperatures (700, 750, 800, 900 °C) and pressures (0.5, 1, 1.5 MPa), using steam and carbon dioxide as gasifying agents. The obtained results showed that in the entire analysed range, the increase in temperature positively affect both the steam and CO₂ gasification of RDF. The formation rates of main components (H₂ and/or CO) of the resulting gas, as well as yields of gas components and maximum carbon conversion degrees increase. However, this positive effect was the greater, the lower the process pressure was. In turn, the effect of pressure was more complex. In the case of RDF steam gasification, an increase in pressure had a negative effect on the process, while when using carbon dioxide as a gasifying agent, an improvement of most analysed parameters was observed; however, only at low temperatures, 700–750 °C. Full article

(This article belongs to the Special Issue Pyrolysis and Gasification of Biomass and Waste)

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16 pages, 3164 KiB

Open AccessArticle

Py-GC-MS Study on Catalytic Pyrolysis of Biocrude Obtained via HTL of Fruit Pomace

by Mariusz Wądrzyk, Marek Plata, Kamila Zaborowska, Rafał Janus and Marek Lewandowski

Energies 2021, 14(21), 7288; https://0-doi-org.brum.beds.ac.uk/10.3390/en14217288 - 03 Nov 2021

Cited by 4 | Viewed by 1474

Abstract

Herein, we proposed new two-stage processing of blackcurrant pomace toward a value-added, hydrocarbon-rich biocrude fraction. The approach consisted of thermochemical liquefaction of a wet-type organic matter into liquid biocrude followed by its upgrade by thermal and catalytic pyrolysis. Particularly, we put effort into investigating the effect of selected catalysts (ZSM-5 and HY zeolite) on the composition of the volatiles released during the pyrolysis of the biocrude. The latter was obtained through liquefaction of the raw material in the binary solvent system of water and isopropanol. The biocrude yield accounted for ca. 45 wt.% of the initial dry biomass. It was a complex mixture of various component groups with an abundant share of oxygenates, especially carboxylic acids and esters. Thereafter, the biocrude was subjected to a pyrolysis study performed by means of the microscale coupled pyrolysis-gas chromatography-mass spectrometry technique (Py-GC-MS). The dominant components identified in the catalytic pyrolytic volatiles were unsaturated hydrocarbons (both cyclic and aliphatic ones) and, to a lesser extent, oxygen and nitrogen compounds. The addition of the ZSM-5 and HY zeolite allowed us to attain the relative total share of hydrocarbons in the volatile fraction equal to 66% and 73%, respectively (in relation to identified compounds). Thus, catalytic pyrolysis over zeolites seems to be particularly prospective due to the promotion of the deoxygenation reactions, which manifested in the noticeable decrease in the share of oxygen compounds in the evolved volatiles. The developed innovative two-stage processing of blackcurrant pomaces allows for obtaining value-added products that could serve as chemicals, biocomponents, and self-contained biofuels as well as bioplastic precursors. The presented contribution brings some new insights into the field of valorization of residuals generated by the food industry sector. Full article

(This article belongs to the Special Issue Pyrolysis and Gasification of Biomass and Waste)

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16 pages, 3207 KiB

Open AccessArticle

Mechanical Durability and Grindability of Pellets after Torrefaction Process

by Arkadiusz Dyjakon, Tomasz Noszczyk and Agata Mostek

Energies 2021, 14(20), 6772; https://0-doi-org.brum.beds.ac.uk/10.3390/en14206772 - 17 Oct 2021

Cited by 3 | Viewed by 2155

Abstract

Renewable energy sources and their part in the global energy mix are beneficial to energy diversification and environment protection. However, raw biomass is characterized by low heating value, hydrophilic properties, various mechanical durability, and the logistic challenges related to transportation and storage. One frequently used process of combined biomass valorization is torrefaction and pelletization, which increase the heating value, homogeneity, and hydrophobicity of the fuel. However, industrial clients need fuel characterized by favorable grindability, whereas, the individual clients (householders) need fuel with high mechanical durability. Due to the different expectations of final customers regarding biomass fuel properties, it is necessary to investigate the influence of the torrefaction on the mechanical durability of the pellets. In this paper, five various types of pellets and their torreficates (obtained at a temperature of 200 and 300 °C) were examined. Then the mechanical durability index D_U and the grindability of the untreated and torrefied pellets were determined. The results indicated that the mechanical durability of untorrefied pellets is significantly greater than torrefied pellets. Interestingly, no significant differences in mechanical durability between torrefied pellets at 200 and 300 °C were observed, For sunflower husk pellets, the D_U index amounted to 95.28 ± 0.72 (untorrefied), 47.22% ± 0.28% (torrefied at 200 °C), and 46.34% ± 0.72% (torrefied at 300 °C). Considering the grindability, as the treatment temperature increased the energy demand for grindability decreased. For example, the grindability of pine tree pellets was 15.96 ± 3.07 Wh·kg⁻¹ (untreated), 1.86 ± 0.31 Wh·kg⁻¹ (torrefied at 200 °C), and 0.99 ± 0.17 Wh·kg⁻¹ (torrefied at 300 °C). The highest difference between raw and torrefied pellets was determined for beetroot pomace pellet: 36.31 ± 2.06 Wh·kg⁻¹ (untreated), 3.85 ± 0.47 Wh·kg⁻¹ (torrefied at 200 °C), and 1.03 ± 0.12 Wh·kg⁻¹ (torrefied at 300 °C). Full article

(This article belongs to the Special Issue Pyrolysis and Gasification of Biomass and Waste)

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Review

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20 pages, 1399 KiB

Open AccessReview

Opportunities and Challenges of High-Pressure Fast Pyrolysis of Biomass: A Review

by Waheed A. Rasaq, Mateusz Golonka, Miklas Scholz and Andrzej Białowiec

Energies 2021, 14(17), 5426; https://0-doi-org.brum.beds.ac.uk/10.3390/en14175426 - 31 Aug 2021

Cited by 18 | Viewed by 3216

Abstract

Most pyrolysis reactors require small sizes of biomass particles to achieve high-quality products. Moreover, understanding the usefulness of high-pressure systems in pyrolysis is important, given the operational challenges they exhibit specific to various biomass materials. To actualize these aspects, the authors first checked previous reviews involving pyrolysis on different biomass and different conditions/situations with their respective objectives and subsections. From these already existing reviews, the team found that there has not been much emphasis on high-pressure fast pyrolysis and its potential in biomass conversion, showing that it is a novel direction in the pyrolysis technology development. Therefore, this review aims to shed more light on high-pressure fast pyrolysis, drawing from (a) classification of pyrolysis; (b) reactors used in fast pyrolysis; (c) heat transfer in pyrolysis feedstock; (d) fast pyrolysis parameters; (e) properties/yields of fast pyrolysis products; (f) high pressure on pyrolysis process; (g) catalyst types and their application; and (h) problems to overcome in the pyrolysis process. This review increases the understanding regarding high-pressure fast pyrolysis. An attempt has been made to demonstrate how high-pressure fast pyrolysis can bring about high-quality biomass conversion into new products. It has been shown that fluidized bed (bubbling and circulating) reactors are most suitable and profitable in terms of product yield. The high-pressure, especially combined with the fast-heating rate, may be more efficient and beneficial than working under ambient pressure. However, the challenges of pyrolysis on a technical scale appear to be associated with obtaining high product quality and yield. The direction of future work should focus on the design of high-pressure process reactors and material types that might have greater biomass promise, as well understanding the impact of pyrolysis technology on the various output products, especially those with lower energy demands. We propose that the increase of process pressure and biomass particle size decrease should be considered as variables for optimization. Full article

(This article belongs to the Special Issue Pyrolysis and Gasification of Biomass and Waste)

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