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Journal ArticleDOI

Recent progress on catalytic pyrolysis of lignocellulosic biomass to high-grade bio-oil and bio-chemicals

TL;DR: In this paper, a review of catalytic pyrolysis of lignocellulose biomass to renewable fuel grade bio-oil and chemicals is presented, along with catalysts type and their catalytic activities in the production of renewable biooil and bio-chemicals.
Abstract: Pyrolysis converts lignocellulosic biomass to bio-oil that can be a precursor to fuel and chemicals for industries. The bio-oil contains high oxygenates fractions that deteriorate the bio-oil fuel properties. Catalysts acted to upgrade the bio-oil through selected bond cleavage reactions such as deoxygenation, cracking, decarbonylation and others reactions. Bulk and supported acid or base catalysts in biomass pyrolysis tailored the production of high-grade bio-oil. The catalytic biomass pyrolysis is an approach that is reliable for producing quality renewable fuel and chemical precursors. This paper elucidated recent studies on catalytic pyrolysis of lignocellulose biomass to renewable fuel grade bio-oil and chemicals. The review discussed the various principal activities on biomass characteristics and their potentials in pyrolysis process to produce the high-grade biofuel precursor. The possible processes used in perpetuating the pyrolysis devolatilisation of biomass are also appraised along with catalysts type, and their catalytic activities in the production of renewable bio-oil and bio-chemicals. Therefore, catalyst development for the upgrade of bio-oils from pyrolysis of biomass to renewable fuel and chemicals precursor remains a topical issue.
Citations
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Journal ArticleDOI
TL;DR: In this article, a review of various pyrolysis process, especially focusing on the effects of essential parameters, the process design, the reactors and the catalysts on the process, is presented.

368 citations

Journal ArticleDOI
TL;DR: In this paper, a review of physicochemical biomass pre-treatment methods used to improve the physiochemical properties of the bio-oils produced from pyrolysis of treated biomass is presented.
Abstract: Bio-oil upgrading can be achieved mainly via three types of methods that are biomass pre-treatment, catalytic upgrading and downstream bio-oil upgrading. The article aim is to review the different physicochemical biomass pre-treatment methods used to improve the physiochemical properties of the bio-oils produced from pyrolysis of treated biomass. Biomass pre-treatment could be classified as physical, thermal, chemical and biological methods. The physical methods, such as grinding and densification improve the biomass particle size and density, affecting the heat flow and mass transfer during pyrolysis, while thermal methods, such as torrefaction, decrease the activation energy of the pyrolysis process and increase the amount of hydrocarbons in the produced bio-oil. The chemical methods generally remove the minerals and alkali metals from the biomass, improve its calorific value and enhance other biomass properties. The biomass pre-treatment methods can be integrated with catalytic pyrolysis to enhance the total carbon yield and aromatic hydrocarbons in the bio-oil. This article provides review of the basic principles of the methods, important parameters that affect biomass properties, highlights the key challenges involved in each treatment method and suggests possible future recommendations to further understand the influence of the pre-treatment methods on bio-oil upgrading. In the last section, the effect of integrated catalytic pyrolysis and pre-treatment methods on bio-oil upgrading is provided.

263 citations

Journal ArticleDOI
TL;DR: It is hoped this review will stimulate further advances in the sustainable production of value-added products from lignin to integrate this invaluable "bio-waste" into the chemical/materials supply chain.
Abstract: Despite the enormous research efforts in recent years regarding lignin depolymerisation and functionalisation, few commercial products are available. This review provides a summary and viewpoint of extensive research in the lignin-to-product valorisation chain, with an emphasis on downstream processing of lignin derived feedstock into end products. It starts with an introduction of available platform chemicals and polymeric derivatives generated from lignin via existing depolymerisation and functionalisation technologies. Following that, detailed analyses of various strategies for the downstream processing of lignin derived platform chemicals and materials into fuels, valued-added chemicals and functional polymers are provided. A concise techno-economic analysis of various downstream processes is conducted based on the market demand of the end product, economic potential and technological readiness, enabling the identification of processes that are potentially both economically competitive and commercially feasible, and shedding light on processes which deserve further technological development. We wish this review will stimulate further advances in the sustainable production of value-added products from lignin to integrate this invaluable “bio-waste” into the chemical/materials supply chain.

232 citations

Journal ArticleDOI
TL;DR: In this article, the potential opportunities for food waste pyrolysis focusing on the conversion of food waste to biochar products were evaluated. But the authors did not consider the food waste composition and the process conditions.
Abstract: Waste generated from anthropogenic activities contributes toward stresses on our natural systems through impacts associated with both production and disposal. Sustainable waste management necessitates that industries shift from the current linear model to a circular based economy, utilizing wastes as raw materials for the production of new products, eg. fuels and chemicals. Biomass and associated waste materials can be converted into value-added products using thermochemical processes. The pyrolysis process is a convenient thermochemical method, whereby biomass is efficiently converted into biofuels, biochars and BBQ briquettes; and further processing yields additional value added products, such as activated carbons, carbon black and printing ink. This paper reviews current development work and evaluates potential opportunities for food waste pyrolysis focusing on the conversion of food waste to biochar products. Overall, it was found that the constituents of the food waste together with the process conditions play a major role in the yield and composition of the produced chars. Moreover, more research work needs to be conducted on food waste to biochar and on mixed food blends in particular.

219 citations

Journal ArticleDOI
TL;DR: A review of the current state of the art was performed in order to search directions toward the most profitable biochar farming applications as discussed by the authors, indicating that a promising direction might be its on-farm production followed by onfarm use and nutrient recycling, or more precisely, special fertilization applications.
Abstract: Biochar refers to the high-carbon, black fine-grained product of biomass pyrolysis. Independent studies repeatedly confirmed that its incorporation into arable land is a reliable carbon sequestration method that significantly improves soil quality. The latest development leads to a reduction in the production cost (− 10 to 30 USD t−1); however, the use of biochar in commercial agriculture remains scarce. The reason is that biochar can substitute lower-quality charcoals (150–300 USD t−1). Therefore, farmers tend to sell their biowaste for energy purposes, respectively, preferring a quick profit over the forgotten soil-improving practices, which hold long-term benefits. A review of the current state of the art was performed in order to search directions toward the most profitable biochar farming applications. There are indications that a promising direction might be its on-farm production followed by on-farm use and nutrient recycling, or more precisely, special fertilization applications.

198 citations

References
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Journal ArticleDOI
TL;DR: In this article, the authors provide a description of the emerging biorefinery concept, in comparison with the current oil refinery, as well as discussion of the most important biomass feedstocks, conversion technologies and final products.

1,754 citations

Journal ArticleDOI
TL;DR: In this article, two general routes for bio-oil upgrading have been considered: hydrodeoxygenation (HDO) and zeolite cracking, where zeolites, e.g. HZSM-5, are used as catalysts for the deoxygenization reaction.
Abstract: As the oil reserves are depleting the need of an alternative fuel source is becoming increasingly apparent. One prospective method for producing fuels in the future is conversion of biomass into bio-oil and then upgrading the bio-oil over a catalyst, this method is the focus of this review article. Bio-oil production can be facilitated through flash pyrolysis, which has been identified as one of the most feasible routes. The bio-oil has a high oxygen content and therefore low stability over time and a low heating value. Upgrading is desirable to remove the oxygen and in this way make it resemble crude oil. Two general routes for bio-oil upgrading have been considered: hydrodeoxygenation (HDO) and zeolite cracking. HDO is a high pressure operation where hydrogen is used to exclude oxygen from the bio-oil, giving a high grade oil product equivalent to crude oil. Catalysts for the reaction are traditional hydrodesulphurization (HDS) catalysts, such as Co–MoS2/Al2O3, or metal catalysts, as for example Pd/C. However, catalyst lifetimes of much more than 200 h have not been achieved with any current catalyst due to carbon deposition. Zeolite cracking is an alternative path, where zeolites, e.g. HZSM-5, are used as catalysts for the deoxygenation reaction. In these systems hydrogen is not a requirement, so operation is performed at atmospheric pressure. However, extensive carbon deposition results in very short catalyst lifetimes. Furthermore a general restriction in the hydrogen content of the bio-oil results in a low H/C ratio of the oil product as no additional hydrogen is supplied. Overall, oil from zeolite cracking is of a low grade, with heating values approximately 25% lower than that of crude oil. Of the two mentioned routes, HDO appears to have the best potential, as zeolite cracking cannot produce fuels of acceptable grade for the current infrastructure. HDO is evaluated as being a path to fuels in a grade and at a price equivalent to present fossil fuels, but several tasks still have to be addressed within this process. Catalyst development, understanding of the carbon forming mechanisms, understanding of the kinetics, elucidation of sulphur as a source of deactivation, evaluation of the requirement for high pressure, and sustainable sources for hydrogen are all areas which have to be elucidated before commercialisation of the process.

1,487 citations

Journal ArticleDOI
TL;DR: In this article, the main steps of pyrolysis and the composition of the products obtained from each constituent were synthesized and the results were used to predict the reactivity and energy content of these products and evaluate their potential use as biofuels in renewable applications.
Abstract: The conversion of biomass by thermochemical means is very promising for the substitution of fossil materials in many energy applications. Given the complexity of biomass the main challenge in its use is to obtain products with high yield and purity. For a better understanding of biomass thermochemical conversion, many authors have studied in TG analyzer or at bed scale the individual pyrolysis of its main constituents (i.e. cellulose, hemicelluloses and lignin). Based on these studies, this original work synthesizes the main steps of conversion and the composition of the products obtained from each constituent. Pyrolysis conversion can be described as the superposition of three main pathways (char formation, depolymerization and fragmentation) and secondary reactions. Lignin, which is composed of many benzene rings, gives the highest char yield and its depolymerization leads to various phenols. The depolymerization of the polysaccharides is a source of anhydro-saccharides and furan compounds. The fragmentation of the different constituents and the secondary reactions produce CO, CO2 and small chain compounds. For temperature higher than 500 °C, the residues obtained from the different constituents present a similar structure, which evolves towards a more condensed polyaromatic form by releasing CH4, CO and H2. As the aromatic rings and their substituent composition have a critical influence on the reactivity of pyrolysis products, a particular attention has been given to their formation. Some mechanisms are proposed to explain the formation of the main products. From the results of this study it is possible to predict the reactivity and energy content of the pyrolysis products and evaluate their potential use as biofuels in renewable applications.

1,234 citations

Journal ArticleDOI
TL;DR: The structure of lignin suggests that it can be a valuable source of chemicals, particularly phenolics as discussed by the authors, but it is the major challenge for converting it into value-added chemicals.
Abstract: The structure of lignin suggests that it can be a valuable source of chemicals, particularly phenolics. However, lignin depolymerization with selective bond cleavage is the major challenge for converting it into value-added chemicals. Pyrolysis (thermolysis), gasification, hydrogenolysis, chemical oxidation, and hydrolysis under supercritical conditions are the major thermochemical methods studied with regard to lignin depolymerization. Pyrolytic oil and syngases are the primary products obtained from pyrolysis and gasification. A significant amount of char is also produced during pyrolysis. Thermal treatment in a hydrogen environment seems very promising for converting lignin to liquid fuel and chemicals like phenols, while oxidation can produce phenolic aldehydes. Reaction severity, solvents, and catalysts are the factors of prime importance that control yield and composition of the product.

1,185 citations

Journal ArticleDOI
23 Nov 2012-Energies
TL;DR: More than two hundred publications have been reviewed, discussed and summarized, with the emphasis being placed on the current status of pyrolysis technology and its potential for commercial applications for bio-fuel production as mentioned in this paper.
Abstract: There has been an enormous amount of research in recent years in the area of thermo-chemical conversion of biomass into bio-fuels (bio-oil, bio-char and bio-gas) through pyrolysis technology due to its several socio-economic advantages as well as the fact it is an efficient conversion method compared to other thermo-chemical conversion technologies. However, this technology is not yet fully developed with respect to its commercial applications. In this study, more than two hundred publications are reviewed, discussed and summarized, with the emphasis being placed on the current status of pyrolysis technology and its potential for commercial applications for bio-fuel production. Aspects of pyrolysis technology such as pyrolysis principles, biomass sources and characteristics, types of pyrolysis, pyrolysis reactor design, pyrolysis products and their characteristics and economics of bio-fuel production are presented. It is found from this study that conversion of biomass to bio-fuel has to overcome challenges such as understanding the trade-off between the size of the pyrolysis plant and feedstock, improvement of the reliability of pyrolysis reactors and processes to become viable for commercial applications. Further study is required to achieve a better understanding of the economics of biomass pyrolysis for bio-fuel production, as well as resolving issues related to the capabilities of this technology in practical application.

1,020 citations