Search

The increasing waste generation trends resulted in growing attention to the technologies that aim to reduce or prevent landfilling. The pyrolysis and gasification of refuse-derived fuel (RDF) allow waste to be turned into new raw materials, like pyrolysis gas and syngas. However, the wet gas cleaning processes result in the production of highly contaminated liquid waste. Phenolic compounds are common constituents of this wastewater and often appear in the wastewater of other industries as well. In this research, the laboratory-scale steam gasification of an RDF char was performed to produce syngas and adsorbent simultaneously. The RDF was previously pyrolyzed at 700 °C maximum temperature in a Hungarian pyrolysis pilot plant with approximately 120 kg h−1 capacity. In this thermal waste processing plant, the pyrolysis gas is already utilised by burning, but currently, the char ends up in landfills. The gasification of char samples was examined with different steam-to-carbon ratios (0.56, 0.84, and 1.12) and duration (30, 60, and 120 min) at 900 °C. Following gasification, the phenol removal capability of the solid by-products was investigated. The results show that its composition and energetic properties make the produced syngas more suitable to use as a raw material in the chemical industry rather than a fuel. At lower concentrations, the effectiveness of the solid by-product for phenol removal was comparable to commercial activated carbon. These are promising results about producing activated carbon from waste without any chemical treatment. [ABSTRACT FROM AUTHOR]

Biomass gasification has emerged as a promising method for producing renewable energy, addressing both energy and environmental challenges. This review examines recent research on gasification simulations, covering a range of topics from process modeling to syngas cleanup. Key areas explored include techniques for syngas cleaning, addressing tar formation, and CO2 capture methods. The aim of this review is to provide an overview of the current state of gasification simulation and identify potential areas for future research and development. This work serves as an invaluable resource for researchers, engineers, and industry professionals involved in biomass gasification modeling. By providing a comprehensive guide to biomass gasification simulation using Aspen Plus software and comparing various modeling approaches, it assists users in selecting the most effective tool for optimizing the design and operation of gasification systems. [ABSTRACT FROM AUTHOR]

This study aims to provide an overview of the growing need for renewable energy conversion and aligns with the broader context of environmentally friendly energy, specifically through producing syngas from biomass. Unlike natural gas, which is mainly composed of methane, syngas contains a mixture of combustible CO, H2, and CnHm. Therefore, optimizing its production requires a thorough examination of various operational parameters such as the gasifying agent, the equivalence ratio, the biofuel type, and the state, particularly in densified forms like pellets or briquettes. As new biomass sources are continually discovered and tested, operational parameters are also constantly evaluated, and new techniques are continuously developed. Indeed, these techniques include different gasifier types and the use or non-use of catalysts during biofuel conversion. The present study focuses on these critical aspects to examine their effect on the efficiency of syngas production. It is worth mentioning that syngas is the primary gaseous product from gasification. Moreover, it is essential to note that the pyrolysis process (prior to gasification) can produce, in addition to tar and char, a mixture of gases. The common feature among these gases is their versatility in energy generation, heat production, and chemical synthesis. The analysis encompasses the resulting gas features, including the yield and composition, mainly through the hydrogen-to-carbon monoxide ratio and the carbon monoxide-to-carbon dioxide ratio, as well as the lower heating value and considerations of the tar yield. [ABSTRACT FROM AUTHOR]

The current work focuses on the usage of a sustainable fuel derived from Senna auriculata seed through pyrolysis for IC engine applications. Batch-type reactor was employed to produce the bio-oil through pyrolysis, and it was found that the optimum temperature of 550 °C is suitable for a maximum yield of 46%. Physical characterization of the produced SA oil is examined as per ASTM standards, and chemical characterization is studied using FTIR, 1HNMR, and GC–MS analysis to study and compare with conventional diesel. The performance of the engine, along with combustion and emission analysis, was carried out with blends of SA and diesel. The results investigated were compared with those of conventional diesel. The efficiency for the SA10 blend was estimated to be 34.5%, which is 1.27% higher than regular diesel fuel under full-load conditions. Emission analysis portrayed the CO and UHC emissions as low, whereas the increase in NOX emissions was due to the high temperature inside the cylinder and the presence of oxygen. The SA10 blends exhibited comparable performance and emission results with commercial diesel fuel under normal working conditions. This research provides an integrated approach to selecting the precise biomass and establishing sustainable bioenergy recovery as the future energy resolution. [ABSTRACT FROM AUTHOR]

This work studies red mud, a residue from the processing of bauxite, as a support catalyst in the thermocatalytic reforming (TCR) process, using wood, digestate, and straw as case studies. Thermocatalytic reforming is a thermochemical process for the conversion of biomass into biofuels, combining intermediate pyrolysis and catalytic reforming and resulting in high‐quality biofuels. The quantity and quality of the catalyst in the postreformer is vital as it influences the reactions taking place in it. Normally, nonreactive components of the char produced in the process act as the catalyst in the postreformer but adding a support catalyst may improve the products. In this work, red mud is introduced in the process by mixing it with the feedstock in a ratio of 1:3. The results, in comparison with normal TCR experiments on the same feedstock materials, show that the introduction of red mud into the process generally reduces the biochar yield and generally increases the biogas and product water yields, and the bio‐oil yield remains constant. Its introduction also increases the hydrogen fraction of the gas and tends to reduce the nitrogen and sulfur content of the products, thus improving their quality. These observations are consistent across feedstock materials and postreformer temperatures. The results therefore suggest that red mud is a good support catalyst for increasing the gas yield, increasing the hydrogen fraction of the gas, and improving the quality of the products from the TCR process. [ABSTRACT FROM AUTHOR]

The conversion of biomass residues into syngas through gasification is attractive for energy and process industry applications. However, transportation, storage, and operational challenges limit the conventional direct solid biomass gasification process. To address these issues, the intermediate conversion of biomass to bio‐oil has emerged as a promising alternative. Bio‐oil offers improved transport and storage capabilities due to its higher mass and energy density, enabling the decoupling of solid biomass supply and syngas demand. This study compares two routes for syngas production: direct gasification of solid biomass and indirect gasification using bio‐oil from biomass pyrolysis as an intermediate with biochar and pyrolysis gas supplying thermal energy to the pyrolysis stage. Biochar combustion provides about 1.4 MJ kg−1 of dry biomass to maintain the pyrolysis temperature at 480°C. Using AspenPlus® simulations, the composition and Low Heating Value of the syngas produced by both routes are analyzed. Energy and exergy analysis at different equivalence ratios and temperatures revealed that direct gasification has higher efficiencies than indirect gasification. At 1000°C and an equivalence ratio of 0.4, the highest energy and exergy efficiencies occurred in direct gasification processes. The energy efficiency of direct and indirect gasification amounted to 62% and 53%, respectively. At the same time, the corresponding exergy efficiencies were 65% and 61%. The syngas of direct and indirect gasification processes is a starting point to produce energy, synthetic fuels, and chemicals; this study provides insights for designing and optimizing biomass gasification processes. [ABSTRACT FROM AUTHOR]

Hybrid thermochemical–biological processes have the potential to enhance the carbon and energy recovery from organic waste. This work aimed to assess the carbon and energy recovery potential of multifunctional processes to simultaneously sequestrate syngas and detoxify pyrolysis aqueous condensate (PAC) for short-chain carboxylates production. To evaluate relevant process parameters for mixed culture co-fermentation of syngas and PAC, two identical reactors were run under mesophilic (37 °C) and thermophilic (55 °C) conditions at increasing PAC loading rates. Both the mesophilic and the thermophilic process recovered at least 50% of the energy in syngas and PAC into short-chain carboxylates. During the mesophilic syngas and PAC co-fermentation, methanogenesis was completely inhibited while acetate, ethanol and butyrate were the primary metabolites. Over 90% of the amplicon sequencing variants based on 16S rRNA were assigned to Clostridium sensu stricto 12. During the thermophilic process, on the other hand, Symbiobacteriales, Syntrophaceticus, Thermoanaerobacterium, Methanothermobacter and Methanosarcina likely played crucial roles in aromatics degradation and methanogenesis, respectively, while Moorella thermoacetica and Methanothermobacter marburgensis were the predominant carboxydotrophs in the thermophilic process. High biomass concentrations were necessary to maintain stable process operations at high PAC loads. In a second-stage reactor, Aspergillus oryzae converted acetate, propionate and butyrate from the first stage into L-malate, confirming the successful detoxification of PAC below inhibitory levels. The highest L-malate yield was 0.26 ± 2.2 molL-malate/molcarboxylates recorded for effluent from the mesophilic process at a PAC load of 4% v/v. The results highlight the potential of multifunctional reactors where anaerobic mixed cultures perform simultaneously diverse process roles, such as carbon fixation, wastewater detoxification and carboxylates intermediate production. The recovered energy in the form of intermediate carboxylates allows for their use as substrates in subsequent fermentative stages. [ABSTRACT FROM AUTHOR]

The present study models and examines a novel integrated process of fast pyrolysis of biomass using a system of solar type of heliostat and a system of energy storage by thermochemical method. This integrated model enables biomass pyrolysis to produce bio-oil, reducing the need of external heat and improving efficiency of pyrolysis. The discussion focuses on three: daily, weekly, and yearly, scenarios for storing solar energy. In addition, the evaluation includes assessing the solar fraction, size of the storage devices, power load of auxiliary heating device, and energyefficiency. The modeling and simulation tasks were conducted using Aspen Plus and Engineering Equation Solver. According to the findings, 0.680 kg per second pyro-oil can be generated from one kilogram per second biomass (hybrid poplar). Also 0.170 kg per second char and 0.160 kg per second gases could be yielded from one kilogram per second of the mentioned biomass. The integrated system yields a solar fraction of 0.850 as the resulting outcome. By utilizing the storage system, the thermal energy needed for pyrolysis system can be reduced from 36.49 to 3.929 MW. [ABSTRACT FROM AUTHOR]

Addressing the issues of low heating efficiency and high carbon emissions in traditional biomass pyrolysis processes, this study explores the potential of induction heating fluidized bed pyrolysis reactor (IHFBR) to enhance heating efficiency, reduce carbon emissions, and increase syngas yield during biomass pyrolysis. The effects of induction heating power (5.7–6.8 kW), carrier gas flowrate (200–800 ml/min), reaction time (2–8 min), and fluidizing medium mass (0–33.0 g) on the yield of gas, liquid, solid products from tobacco stem (TS) pyrolysis in the IHFBR are assessed. The results show IHFBR demonstrates higher syngas yield from TS pyrolysis, reaching 356.9 ml/g-TS at 700 °C and 6 min, with CO and H 2 comprising 28.5 vol% and 29.6 vol% of the total gas volume, respectively. This represents a substantial increase in syngas yield by 67.6%, 137.2%, and 526.9%, respectively, compared to conventional fluidized bed, induction and resistance furnace heating fixed beds. [Display omitted] • Induction heating fluidized bed reactor (IHFBR) is developed for biomass pyrolysis. • Tungsten rod with fast self-heating rate (9.7–20.3 °C/s) serves as induction medium. • IHFBR creates localized high-temperature zones and enhances mass/heat transfer. • IHFBR achieves lower solid and liquid yields, and higher gas and syngas yields. • IHFBR boosts syngas by 67.6%, 137.2%, and 526.9% compared to traditional methods. [ABSTRACT FROM AUTHOR]

This study focuses on investigating the potential of methane pyrolysis process for low-carbon, low-cost hydrogen production when compared to alternative hydrogen production technologies. The design, techno-economic analysis, and GHG emission assessment of two different methane pyrolysis configurations, molten metal-based and thermal plasma-based, are conducted. In addition, to assess the effect of heat sources on both environmental and economic aspects of methane pyrolysis, three heating options are considered for the molten metal-based process: a gas-fired heater, a hydrogen-fired heater, and an electrical heater. Results are then compared against other hydrogen production technologies, including electrolysis, SMR without CCS, SMR with CCS, and biomass gasification. The data required for techno-economic analysis and assessing GHG emissions is obtained from Aspen Plus® process simulation models and U.S. DOE's H2A Production Models. Our results indicate that the H 2 minimum selling price associated with pyrolysis systems are almost always lower than that for SMR with CCS considering a natural gas price of $6/GJ, an electricity price of $0.06/kWh, and a carbon black price of $200/t. However, to achieve a H 2 minimum selling price lower than that of SMR without CCS, a carbon black price higher than $500/t is required. Furthermore, the impact of the carbon intensity of the electricity grid and natural gas supply chain for different geographical locations are evaluated. For instance, the results for British Columbia revealed that the GHG emissions of the methane pyrolysis fall within the range of 0.76 and 2.58 kg CO 2 eq./kg H 2 and can be as low as 50% of that of the SMR with CCS for molten metal-H 2 fired configuration. The highest GHG emissions are encountered in the SMR and electrolysis pathways. These analyses show the potential of methane pyrolysis in achieving both lower H 2 minimum selling price and GHG emissions, especially when considering solid carbon as a marketable co-product. • The impacts of system configurations on H 2 minimum selling price and GHG emissions of pyrolysis is investigated. • Pyrolysis is compared against electrolysis, SMR without/with CCS, and biomass gasification. • H 2 minimum selling price for pyrolysis is almost always lower than that for SMR with CCS. • Pyrolysis has a H 2 minimum selling price lower than SMR without CCS when carbon black price is higher than $500/t. • GHG emissions of the methane pyrolysis can be as low as 50% of that of the SMR with CCS. [ABSTRACT FROM AUTHOR]

For a long time, fossil fuel has been a part of our everyday lives and has constantly led to the emission of carbon dioxide (CO2) into the environment. The release of methane (CH4) into our surroundings can be caused by the decomposition of organic wastes produced by our daily activities; CH4 produced by human activity is responsible for at least 25 % of global warming. CH4 is a known potent greenhouse gas that can trap about 35 times more heat than CO2. These greenhouse gases play a role in climate change and global warming. It, therefore, becomes important to explore measures for decarbonizing our environment. Biomethane production using our generated waste is a promising decarbonization approach with significant potential for mitigating greenhouse gas emissions. This paper overviews potential biomass methanation feedstocks and investigates several technologies, such as anaerobic digestion, combined pyrolysis and methanation, and combined gasification and methanation. SWOT analysis of waste conversion to biomethane was conducted, and important points related to the scaling-up of biomethane production processes were outlined. Also, insights into prospects for promoting biomass methanation deployment were provided. In conclusion, biomass methanation has great potential for producing sustainable energy. Hence, collaboration between industrialists, researchers, government agencies, and stakeholders including an understanding of the financial investments, return on investments, or potential subsidies and incentives could enhance the practicality of the proposed solution. Research and development should be continuously carried out as they are necessary to scale up and promote the technology. Also, there should be technical training for stakeholders as it is essential for the smooth development of the sector. [ABSTRACT FROM AUTHOR]

The demand for sustainable energy sources has increased owing to environmental concerns, such as climate change, rising energy demand and rapid industrialization. Biomass utilization for bioenergy and value‐added chemical production has become essential for creating a circular low‐carbon bioeconomy and sustainable waste management techniques. This review focuses on thermochemical processes and analyzes the trends of biomass utilization for energy production in the EU over the last decade. It discusses the current state‐of‐the‐art of gasification, pyrolysis, advanced combustion and liquefaction technologies, and presents the individual challenges and prospects of each process. A comprehensive overview of previous studies related to each conversion technology is provided to pave the way for future thermochemical, biochemical and integrated biomass valorization studies. Additionally, the review discusses biomass thermochemical conversion processes, which are combined with carbon capture, such as gasification, liquefaction and pyrolysis. These processes offer the potential to achieve negative net atmospheric carbon emissions, which can contribute to global warming mitigation efforts. [ABSTRACT FROM AUTHOR]

In this study, a systematic and quantitative investigation of the pyrolysis characteristics of biomass was conducted in a fixed‐bed tubular reactor, and the influence of pyrolysis temperature on product yields, gas emission characteristics, and syngas compositions as well as physicochemical characterization of resulting solids (i.e., char/ash morphologies, mineral transformations, and elemental compositions) was explored in detail. The pyrolysis experiments were performed under N2, and the resulting solid characterization was detected by XRD, SEM, and EDX. The results indicated that with increasing the pyrolysis temperature from 400 to 800°C, the gaseous product yields increased from 54.9% to 66.7%, while the solid product yield showed a reverse trend, varying within 27.7%–40.5%. Meanwhile, the volume fraction of H2 in syngas increased from 7% to 33%, while the CO2 presented an opposite trend, suggesting that high temperature favored H2 formation and inhibited CO2 formation. On the whole, the CO and CO2 emissions were prior to CH4, H2, and CnHm in sequence. A large amount of sylvite (KCl), quartz (SiO2), dolomite (CaMg(CO3)2), and pyroxene (CaMgSi2O6) in the resulting solids were identified in crystal phases. Higher pyrolysis temperature had a significant influence on solid microstructures, resulting in a relatively higher slagging tendency due to low melting eutectics containing K‐rich and Ca‐rich minerals. [ABSTRACT FROM AUTHOR]

To solve the problems of low gasification efficiency and high tar content caused by solid–solid contact between biomass and oxygen carrier in traditional biomass chemical looping gasification process. The decoupling strategy was adopted to decouple the biomass gasification process, and the composite oxygen carrier was prepared by embedding Fe2O3 in molecular sieve SBA-16 for the chemical looping reforming process of pyrolysis micromolecular model compound methane, which was expected to realize the directional reforming of pyrolysis volatiles to prepare hydrogen-rich syngas. Thermodynamic analysis of the reaction system was carried out based on the Gibbs free energy minimization method, and the reforming performance was evaluated by a fixed bed reactor, and the kinetic parameters were solved based on the gas–solid reaction model. Thermodynamic analysis verified the feasibility of the reaction and provided theoretical guidance for experimental design. The experimental results showed that the reaction performance of Fe2O3@SBA-16 was compared with that of pure Fe2O3 and Fe2O3@SBA-15, and the syngas yield was increased by 55.3% and 20.7% respectively, and it had good cycle stability. Kinetic analysis showed that the kinetic model changed from three-dimensional diffusion to first-order reaction with the increase of temperature. The activation energy was 192.79 kJ/mol by fitting. This paper provides basic data for the directional preparation of hydrogen-rich syngas from biomass and the design of oxygen carriers for pyrolysis of all-component chemical looping reforming. [ABSTRACT FROM AUTHOR]

In this work, a simplified comprehensive three-dimensional numerical model is developed to study the effect of hydrogen production on co-gasification of biomass and low-density polyethylene (LDPE). CFD software AVL Fire 2020 inbuilt algorithms were employed to develop the gas phase while the solid phase was developed by user-defined FORTRAN subroutines. Solid hydrodynamics, fuel conversion, homogenous and non-homogenous chemical reactions, and heat transfer, including radiation, subroutines were defined and incorporated into AVL FIRE explicitly. Species concentrations of the syngas were analyzed for co-gasification of Beechwood and LDPE for three distinct types of bed materials (silica sand, Na-Y zeolite, and ZSM-5 zeolite). Then, the model is validated with experiment results available in the literature for a lab-scale fluidized bed reactor. The highest hydrogen production was observed in Na-Y zeolite followed by ZSM-5 zeolite and silica in both numerical and experimental analysis for the co-gasification of Beechwood and LDPE, providing a reasonable agreement between the numerical and the experimental results. Therefore, the current model predicts the enhancement of the quality of hydrogen-rich syngas through the application of co-pyrolysis within a fluidized bed reactor, incorporating a catalytic bed material. [ABSTRACT FROM AUTHOR]

A two-stage process of biomass pyrolysis and dry/steam reforming for adjustable H2/CO syngas production is proposed. This process can not only control the ratio of H2/CO, but also realize the utilization of coke generated in the gasification process and reduce the energy consumption of biomass gasification, as well as the utilization of CO2. The process model was built after the pyrolysis experiment, and the thermodynamics of dry/steam reforming was studied under different reforming temperature, CO2/C, and H2O/C. With the increase in reforming temperature, the volume of CO increases gradually, and the volume of H2 increases first and then decreases. With the increase in CO2/C, the volume of CO increases gradually and the volume of H2 decreases gradually, while with the increase in H2O/C, the volume of CO decreases and the volume of H2 increases, so diverse-H2/CO-ratio syngas can be obtained by adjusting the H2O and CO2 input as well as the reforming temperature. For the production of syngas with H2/CO = 2, by comparing the total volume of gas produced and energy consumption, the optimum reforming conditions are obtained: CO2/C = 0.5, H2O/C = 2, and the reforming temperature is 770 ℃. Similarly, the optimum reforming conditions for the production of syngas with H2/CO = 3 are: CO2/C = 0, H2O/C = 2, and the reforming temperature is 770 ℃. [ABSTRACT FROM AUTHOR]

The pyrolysis of three different biomasses, rice husk (RH), zoita wood sawdust (ZW) and pine wood sawdust (PW), was studied at 500 °C in a multipurpose unit at the bench scale to determine the yields of the different products and the compositions and properties of the liquid products, with particular emphasis given to the alquitranous fractions (tars). It was possible to link the characteristics of the tars with the compositions of the raw biomasses and verify their potential in various applications. The analytical techniques employed in the characterization of biomasses included lignin, celulose and hemicellulose analysis, ultimate and proximate analysis and thermogravimetry–mass spectrometry analysis (TG-MS). Elemental analysis, gas chromatography–mass spectrometry (GC-MS), nuclear magnetic resonance spectroscopy (1H NMR), Fourier transform infrared spectroscopy (FTIR) and size exclusion chromatography (SEC) were used to characterize the tars. The tar yields were 1.8, 7.4 and 4.0 %wt. in the cases of RH, ZW and PW, respectively. The tars showed higher carbon content, between 60.3 and 62.2 %wt., and lower oxygen content, between 28.8 and 31.6 %wt., than the corresponding raw biomasses. The main components of the tars had aromatic bases, with phenols representing more than 50%. Tar RH included more guaiacols, while Tars ZW and PW included more phenols and alkylated phenols. [ABSTRACT FROM AUTHOR]

The thermo-chemical conversion of biomass wastes is a practical approach for the value-added reclamation of bioenergy in large quantities, and pyrolysis plays a core role in this process. In this work, poplar (PR) and cedar (CR) were used as staple wood biomasses to investigate the apparent kinetics of TG/DTG at different heating rates. Secondly, miscellaneous wood chips (MWC), in which PR and CR were mixed in equal proportion, were subjected to comprehensive investigations on their pyrolysis behavior and product evolution in a fixed bed reactor with pyrolysis temperature, catalyst, and the flow rate H2O steam as influencing factors. The results demonstrated that both PR and CR underwent three consecutive pyrolysis stages, the TG/DTG curves shifted to higher temperatures, and the peak temperature intervals also enhanced as the heating rate increased. The kinetic compensation effect expression and apparent reaction kinetic model of CR and PR pyrolysis were obtained based on the law of mass action and the Arrhenius equation; the reaction kinetic parameter averages of Ea and A of its were almost the same, which were about 72.38 kJ/mol and 72.36 kJ/mol and 1147.11 min−1 and 1144.39 min−1, respectively. The high temperature was beneficial for the promotion of the pyrolysis of biomass, increased pyrolysis gas yield, and reduced tar yield. This process was strengthened in the presence of the catalyst, thus significantly increasing the yield of hydrogen-rich gas to 117.9 mL/g-biomass. It was observed that H2O steam was the most effective activator for providing a hydrogen source for the whole reaction process, promoted the reaction to proceed in the opposite direction of H2O steam participation, and was beneficial to the production of H2 and other hydrocarbons. In particular, when the flow rate of H2O steam was 1 mL/min, the gas yield and hydrogen conversion were 76.94% and 15.90%, and the H2/CO was 2.07. The yields of H2, CO, and CO2 in the gas formation were significantly increased to 107.35 mL/g-biomass, 53.70 mL/g-biomass, and 99.31 mL/g-biomass, respectively. Therefore, H2 was the most dominant species among gas products, followed by C-O bond-containing species, which provides a method for the production of hydrogen-rich gas and also provides ideas for compensating or partially replacing the fossil raw material for hydrogen production. [ABSTRACT FROM AUTHOR]

In this study, co‐generation from rice straw based on pyrolysis and gasification was studied by experimental and modeling approaches. Pyrolysis experiment results show that improving pyrolysis temperature will benefit the yield of gas and bio‐oil, while reducing the yield of bio‐char. The BET (Brunauer, Emmett, and Teller) surface area of bio‐char reached a maximum of 143.26 m2/g when the temperature was increased to 550°C. For co‐generation in this study, an optimized pyrolysis temperature of 500°C was selected. With respect to gasification, air equivalence ratio (ER) largely influenced the syngas yield and composition. At ER = 0.25, the concentration of H2 and CO reached a maximum of 17.8 wt% and 16.2 wt%. Based on the experimental results, an Aspen Plus model was built to evaluate the mass and energy balance during co‐generation. Furthermore, a life cycle assessment method was used to evaluate the greenhouse gas emission during co‐generation process initialed from rice straw planting. Results show that the greenhouse gas emission intensities of the two co‐generation systems were 2.92 and 3.51 g CO2/MJ respectively, which were much lower than traditional fossil fuels. [ABSTRACT FROM AUTHOR]

There is an urgent need for research efforts aimed at developing technologies capable of efficiently gasifying sustainable biomasses composed of organic waste from various industrial processes. This work constitutes a crucial contribution to the field by addressing the pressing need for sustainable biofuels production. It introduces an innovative open-source mathematical model, implemented in Python, designed to simulate the complex process of gasifying advanced biomasses within a downdraft gasifier. Termed the “bi-equilibrium with tar cracking” model, it represents a significant advancement in the modelling of biomass gasification, offering a versatile and comprehensive tool for researchers and engineers in the field. The model’s multi-zone framework is particularly noteworthy, as it meticulously divides the downdraft gasifier into four distinct zones: the drying zone, where moisture content is reduced; the pyrolysis zone, where biomass undergoes thermal decomposition; the separation zone, where tar and other pyrolysis products are destined to different treatments; and the gasification zone, where syngas is produced. This granular approach enables a detailed analysis of each stage, facilitating a deeper understanding of the intricate gasification process. Furthermore, the model’s multi-scale nature incorporates parameters within the separation section, allowing for the simulation of molecular-level phenomena, such as the formation of preferential pathways. These pathways play a pivotal role in determining the composition of the resulting syngas, making the model exceptionally valuable for predicting and optimizing syngas quality. [ABSTRACT FROM AUTHOR]

The present study developed an ASPEN plus model for the study of the gasification behaviors of biomass in a dual fluidized bed (DFB) using steam as gasification agent. Model validation was performed by comparing the predicted results with the experimental data obtained from a steam-blown DFB gasification system and, a good agreement was attained. Sensitivity analysis was done to obtain producer gas composition using wood pellets and different gasification parameters like H2 yield, gas yield, H2/CO, tar yield, cold gas efficiency (CG-E) and char conversion efficiency (CC-E) using gasification temperature (750–900 °C), steam/biomass ratio, S/B (0.28–1.72) and steam temperature, ST (300–700 °C). Increasing the temperature and S/B contributed to the yield of H2 and the tar conversion rate. The results showed that both variables (temperature and S/B) have a strong positive influence on the quality and quantity of the produced syngas. Results showed that H2 content increased while CO and CH4 decreased with increasing S/B from 0.28 to 1.72 at 850 °C. The gas yield and H2/CO increased from 0.83 to 1.21 Nm3/kg and 0.9 to 1.87 with increasing S/B from 0.28 to 1.72, respectively, while tar yield decreased from 9.1 to 8.02 g/Nm3. The content of H2, H2 yield and CG-E increased with the rise of ST from 300 to 700 °C, while an opposite trend was achieved for tar yield. [ABSTRACT FROM AUTHOR]

This study investigated the role of K and steam in upgrading syngas quality over biochar in a two-stage fixed-bed reactor. The integration of K-char catalyst and steam greatly increased syngas (H 2 +CO) and H 2 production. The syngas products yield (19.76 mmol/g biomass) and a H 2 yield (11.14 mmol/g biomass) were achieved when K-char was used as catalyst in the presence of steam. In general, four ways could be concluded to promote volatiles reforming to improve syngas quality by K and steam: Firstly, K and steam interaction with biochar increased the surface area and developed the porous structure of biochar, providing the pyrolytic intermediates with full complete contact with the char surface, and improving the chance of contact with the active sites. Secondly, the condensation reactions of biochar were inhibited by K and steam, thus preventing the reduction of active groups on the aromatic ring of biochar. Thirdly, K and steam promoted the formation of O-containing groups with high reactive activity on the char surface, such as –COO and –CO. Moreover, volatile K migrated in biochar matrix during catalytic reforming, and steam inhibited the release of K in biochar, resulting in more K retaining on the char surface in the form of -COK and -COOK acting as the active sites, which ultimately improved the catalytic activity of biochar, and promoted tar destruction and hydrocarbon reforming. [Display omitted] • K-form char combined with steam greatly increased syngas (H 2 +CO) and H 2 production. • Steam, carbon skeleton and K in biochar improved the secondary catalytic reforming reaction efficiency. • The catalytic effect of biochar is related to its surface area, O-containing groups and K migration. • Mechanism of K-form char combined with steam to improve syngas quality is well discussed. [ABSTRACT FROM AUTHOR]

Pyrolysis and related thermal conversion processes have shown increased research momentum in recent decades. Understanding the underlying thermal conversion process principles alongside the associated/exhibited operational challenges that are specific to biomass types is crucial for beginners in this research area. From an extensive literature search, the authors are convinced that a tutorial review that guides beginners particularly towards pyrolysis implementation, from different biomasses to the thermal conversion process and conditions, is scarce. An effective understanding of pre-to-main pyrolysis stages, alongside corresponding standard methodologies, would help beginners discuss anticipated results. To support the existing information, therefore, this review sought to seek how to navigate pyrolysis implementation, specifically considering factors and thermochemical operating methods for biomass conversion, drawing the ideas from: (a) the evolving nature of the thermal conversion process; (b) the potential inter-relatedness between individual components affecting pyrolysis-based research; (c) pre- to post-pyrolysis' engagement strategies; (d) potential feedstock employed in the thermal conversion processes; (e) the major pre-treatment strategies applied to feedstocks; (f) system performance considerations between pyrolysis reactors; and (g) differentiating between the reactor and operation parameters involved in the thermal conversion processes. Moreover, pre-pyrolysis activity tackles biomass selection/analytical measurements, whereas the main pyrolysis activity tackles treatment methods, reactor types, operating processes, and the eventual product output. Other areas that need beginners' attention include high-pressure process reactor design strategies and material types that have a greater potential for biomass. [ABSTRACT FROM AUTHOR]

Escalating global population and expanding industrialisation have significantly contributed to an increased demand for plastics. Methods for plastic waste disposal predominantly involve landfilling, which consumes space and pollutes soil and water bodies, posing a substantial threat to the environment and public health. The critical challenge herein lies in efficiently managing the abundant biomass and plastics waste. Here we review gasification and pyrolysis, two prominent waste treatment processes. Co-pyrolysis of plastics and biomass exhibits a synergistic effect, significantly enhancing the yield and quality of bio-oil, biochar, and syngas. Integration of gasification and pyrolysis reduces activation energy, increases hydrogen production during co-gasification, and improves bio-oil calorific value. The gasification of polyethylene terephthalate with air in the presence of activated carbon limits tar formation with enhanced syngas production. Steam gasification enhances hydrogen generation by up to 40.0% compared to air gasification. Selective catalysts in the integrated pyrolysis–gasification process of biomass and plastics mixtures demonstrate optimisation of the production of high-purity carbon nanotubes and bio-oil. Application of innovative approaches such as microwaves, steam purging, and catalysts like zeolite or composite catalysts enhance heat transfer mechanism, tar cracking, and devolatilisation. [ABSTRACT FROM AUTHOR]

The present communication is focused predominantly on important R&D solutions relevant to renewable energy technologies covering the following: (i) Innovative heat transfer fluid and thermal storage technology based on a molten salt mixture developed by ENEA for large-scale heat storage. The system uses a parabolic trough collector, compared with diathermic oil, which allows higher operating temperature, resulting in significant benefits to the plant's operation, safety and the environment. (ii) The world's first solar disk powered by air micro turbine developed by ENEA. (iii) An innovative steam-explosion prototype plant installed at ENEA for the pre-treatment of lignocellulosic biomass and the fractionation of bio components to generate ethanol from lignocellulosic material using hemicellulose and lignin. (iv) The production of hydrogen-enriched biogas using steam as the gasification agent, which helps in obtaining nearly nitrogen-free product gas and with a high calorific value of around 12 MJ/Nm3 dry gas and a high percentage of hydrogen (up to 55%) while using steam as the gasifying agent in the presence of a catalyst. (v) A rotary kiln plant, with the main purpose being to develop and optimize a thermo-chemical process to convert used rubber tyres so as to recover material and energy, as well as other solid products, with high value-added "Activated carbon" and synthesis gas. [ABSTRACT FROM AUTHOR]

Food waste, particularly animal-derived waste, presents a significant challenge globally, prompting the need for sustainable management strategies. In 2022, the amount of food waste per capita reached 131 kg/capita in the EU (European Union), which is why the search for environmentally friendly ways to manage food waste through thermochemical conversion processes has gained momentum in recent years. Animal-derived waste is a good source of organic matter (proteins, lipids, and polysaccharides) and mineral compounds (calcium phosphate, mostly hydroxyapatite). This composition makes animal-derived waste valuable for the extraction of chemical compounds, such as hydroxyapatite (HAp), which constitutes up to 70 wt% of animal bones; keratin; collagen; and hyaluronic acid (HA), to produce pharmaceutical, medical, or industrial by-products. The thermochemical conversion of chicken bones through pyrolysis and gasification creates a new opportunity to valorize this type of waste by reintroducing valuable by-products into the economy and thus achieving sustainable waste management objectives. The results of this study showcase the multiple applications of the pyrolysis of chicken bone waste products (as adsorbents in aqueous mediums, catalysts, fertilizers, and biomedical applications) and the necessity of a better exploration of the gasification process of chicken bone waste. Therefore, this study explores the properties of animal-derived waste and discusses the pyrolysis and gasification of chicken bone waste, the influence of process conditions on product yields, and the catalytic enhancement of these thermochemical processes. [ABSTRACT FROM AUTHOR]

Biomass gasification has emerged as a promising method for producing renewable energy, addressing both energy and environmental challenges. This review examines recent research on gasification simulations, covering a range of topics from process modeling to syngas cleanup. Key areas explored include techniques for syngas cleaning, addressing tar formation, and CO2 capture methods. The aim of this review is to provide an overview of the current state of gasification simulation and identify potential areas for future research and development. This work serves as an invaluable resource for researchers, engineers, and industry professionals involved in biomass gasification modeling. By providing a comprehensive guide to biomass gasification simulation using Aspen Plus software and comparing various modeling approaches, it assists users in selecting the most effective tool for optimizing the design and operation of gasification systems.

The influence of a CO2 reactive medium and of a volume in the range 200–600 mL on the yield of basic components (CO, CO2, H2, and CH4) of a producer gas in microwave heating of biomass has been investigated. The dependences of the moderate and maximum concentrations of the gases on the volume of carbon dioxide fed to the chamber of a microwave reactor have been determined. Trends of variation in the concentrations of the enumerated gases with time have been obtained. Times of the onset of release of the concentrations of the gas components and their duration with variation of the CO2 volume fed to the chamber have been established. The influence of the feed of reactive gases on the mass of the char has been investigated. It has been shown that the injection of CO2 into the reactor chamber exerts a positive influence on the intensification of microwave pyrolysis of the biomass, with the result that the yield of volatiles of the formed gas mixture rises. [ABSTRACT FROM AUTHOR]

Biomass gasification is a thermochemical process used to generate hydrogen and methane for energy applications. This experimental study compares the products formed from sugarcane bagasse, bamboo, and rice-straw and evaluates the calorific value of the gas and the efficiency of homogeneous cracking in a novel, two-stage, downdraft, fixed-bed reactor. The formation of tar and the presence of carbon oxides (COx) in the gaseous product are some of the major problems with biomass gasification. In order to solve these issues, calcium oxide (CaO) is introduced with the feed in a 1:1 mass ratio as a CO2 sorbent, and its effect on the amount of tar is studied across the chosen biomasses. Experiments are conducted with the pyrolysis stage at 773 K and the air-gasification stage at 1073 K. The tar cracking efficiency of 97% is obtained with CaO for all biomasses. Rice-straw showed the highest syngas ratio of 1.83 and the volume of hydrogen increased by 13% after the addition of CaO, while bamboo had a 16% rise in hydrogen and showed the highest LHV of 12.21 MJ/m³, followed by bagasse with an LHV of 11.50 MJ/ m3 . The gasification efficiency for bamboo is the highest overall for both the processes. [ABSTRACT FROM AUTHOR]

This article introduces a pyrolysis chemical looping reforming (PCLR) process that produces carbon‐negative syngas in autothermal operation. To enhance the system's carbon negativity, a process configuration with oxygen carrier two‐stage regeneration is adopted, enabling internal CO2 utilization. The PCLR process is systematically evaluated and compared to chemical looping gasification and steam gasification processes in the process performance, energy efficiency, and environmental impact using a process model. Results reveal significant improvements over chemical looping gasification, including 69%, 45%, and 4% improvement in syngas yield, energy efficiency, and environmental benefit. Process analysis demonstrates that decoupling volatile reforming from pyrolysis and combustion enhances syngas quality, energy efficiency, and process flexibility. While the two‐stage regeneration sacrifices syngas production, it contributes to a 4% increase in carbon negativity and a 15% reduction in carbon emissions. Thus, the PCLR process effectively overcomes the limitations of chemical looping gasification systems and exhibits excellent process intensification performance. [ABSTRACT FROM AUTHOR]

Producing sustainable energy to meet the world's current demands is a major concern. Municipal Solid Waste (MSW) is a good source for producing sustainable energy and currently gets abundantly generated in India. Usually MSW is screened to prepare Segregated Dry Municipal Solid Waste (SDMSW) pellets before subjecting it to gasification to produce producer gas. But, generation of hazardous byproducts is a key issue in the conversion of SDMSW to producer gas. In the present work a multi-purpose downdraft gasifier has been designed and developed that can process biomass and SDMSW pellets blend while reducing undesirable byproducts such as tar and ash. The calorific value, chemical composition and byproduct content of the SDMSW pallets blended with biomass are determined prior to gasification. The feedstock is characterised using ultimate and proximate analysis, and the calorific value is determined using a bomb calorimeter. Gas chromatography is used to assess the quality of the producer gas. The results indicate that adding 50% SDMSW to Biomass results in good efficiency. [ABSTRACT FROM AUTHOR]

The fast depletion of fossil fuels and growing concerns about environmental sustainability have increased interest in using biomass as a renewable energy source. Fast pyrolysis, a thermochemical conversion process, has emerged as a promising technique for converting biomass into valuable biofuels and bio-based chemicals. The aim of this literature review is to comprehensively analyze recent advances in biomass fast pyrolysis, focusing on the principles, process parameters, product yields, and potential applications of biomass fast pyrolysis. This comprehensive review, based on an in-depth analysis of 61 scientific papers and 4 patents, provides an overview of various biomass technologies (combustion, gasification, pyrolysis) used for biofuel production. It focuses on the principles, benefits and applications of these technologies and serves as a valuable resource for researchers, engineers and policy makers. Based on the wealth of information from rigorously selected sources, we explore the key process parameters and reactor types associated with each technology, providing insight into its efficiency and product composition. [ABSTRACT FROM AUTHOR]

In the modern world, as the population rises and fossil fuel supplies decline, energy demands continue to rise. Moreover, the use of fossil fuels harms the ecology, contributing to pollution and global warming. In order to overcome these difficulties, several approaches are revealed, such as the utilization of biomass as a renewable source of energy. Studies revealed that biomass can be converted into bioenergy via several thermal conversion processes, like pyrolysis, gasification, and torrefaction. Pyrolysis is the most convenient process to obtain three different types of biofuels (biochar as a solid, bio-oil as a liquid, and syngas as a gas). The biofuels produced in this process are normally lower in quality and cannot be used directly as fuel because they contain many undesirable components. Catalytic pyrolysis is one of the best processes to upgrade the quality of biofuels. Several varieties of catalysts are used in the catalytic pyrolysis process (ex situ and in situ). Due to stable operating conditions, both catalytic and non-catalytic pyrolysis procedures produce biochar that has a consistent output. Meanwhile, the effects of catalysts in the catalytic pyrolysis process considerably enhance the quality and quantity of bio-oils and syngas. By removing the unwanted oxygenated and nitrogenous components, the bio-oils produced through the catalytic pyrolysis method have a higher calorific value, reduced viscosity, and improved stability. Many researchers have looked at ways to increase the rate of pyrolysis, whereas a few have focused on maximizing the effects of the factors in order to improve the efficiency of catalytic pyrolysis. This review addresses the impact of catalysts on the catalytic pyrolysis of biomass to enhance the quality of the bio-oils in great detail. Machine learning and techno-economic analysis were investigated, as well as the future potential of the catalytic pyrolysis method for the generation of bio-oil. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic has caused a heavy expansion of plastic pollution due to the extensive use of personal protective equipment (PPE) worldwide. To avoid problems related to the entrance of these wastes into the environment, proper management of the disposal is required. Here, the steam gasification/pyrolysis technique offers a reliable solution for the utilization of such wastes via chemical recycling into value-added products. The aim was to estimate the effect of thermo-chemical conversion temperature and steam-to-carbon ratio on the distribution of gaseous products obtained during non-catalytic steam gasification of 3-ply face masks and KN95 respirators in a fluidized bed reactor. Experimental results have revealed that the process temperature has a major influence on the composition of gases evolved. The production of syngas was significantly induced by temperature elevation from 700 °C to 800 °C. The highest molar concentration of H2 gases synthesized from both types of face masks was estimated at 800 °C with the steam-to-carbon ratio varying from 0 to 2. A similar trend of production was also determined for CO gases. Therefore, investigated thermochemical conversion process is a feasible route for the conversion of used face masks to valuable a product such as syngas. [ABSTRACT FROM AUTHOR]

The increasing demand for energy and the depletion of fossil energy supplies require research to find renewable energy sources. Biomass is one of the most promising renewable energy sources. Melaleuca cajuputi and Shorea leprosula are two types of wood plants that are widely available in Indonesia. This study aims to explore the potential of biomass derived from these plants, Melaleuca Cajuputi being a swamp-growing plant and Shorea being a land-growing plant, through a gasification process to produce syngas containing hydrogen and methane gases. The pyrolysis of Melaleuca cajuputi and Shorea sawdust was conducted using a fixed bed reactor at temperatures ranging from 200°C to 450°C, with a heating rate of 10°C/minute for a duration of one hour. The hydrogen and methane gases produced from the pyrolysis process were analyzed to determine the syngas characteristics. Additionally, an FTIR test was performed to provide further support for the experimental analysis. The experimental results demonstrate that Melaleuca Cajuputi wood exhibits stronger hydrogen bonds compared to Shorea wood. Consequently, Shorea wood generates hydrogen gas at lower temperatures and produces a greater quantity of methane gas. The peak hydrogen gas content was observed in Melaleuca Cajuputi and Shorea woods at temperatures of 315°C, with concentrations of 1746 ppm and 1503 ppm, respectively. On the other hand, the highest methane gas content was recorded in Shorea and Melaleuca Cajuputi woods at temperatures of 370°C and 318°C, respectively, with concentrations of 200,000 ppm and 63,200 ppm. The intensity of functional groups in biomass has a significant impact on the gas produced during pyrolysis. [ABSTRACT FROM AUTHOR]

Oil scum is a blackish gel collected from the air flotation of the oil-bearing wastewater from oil refinery plants. It commonly contains 37.5% water, 52.3% tar, and 10.2% inorganic substance. It is categorized as a regulated hazardous waste and often disposed of as an additive in cement rotary kiln. In this study, the tar in the oil scum was converted to valuable volatiles using Fe-rich cold-rolling sludge as the catalyst in the pyrolysis process. Results showed that the conversion efficiency of tar to gas reached 52.2% with the addition of cold-rolling sludge, a 73% increase from direct pyrolysis. This conversion efficiency was also higher than using other additives, for example, alumina, KOH, and dolomite. The oil scum contained 34.5% aromatics and 33.2% saturated hydrocarbons, both of which were completely converted to base oil and gas product during the pyrolysis process. The base oil contained 79.5% chain hydrocarbons, and the combustible gas had 20.6% H2, 12.8% CH4, and 48.4% C2/C4 hydrocarbons. The abundant hematite in the added cold-rolling sludge was converted to magnetite, FeO, and Fe during the pyrolysis process, and the redox cycling of Fe-oxides/element-Fe enabled the dehydrogenation of aromatics and the deoxygenation of the oxygen-containing chain hydrocarbons. As a result, the polycondensation of polycyclic aromatic hydrocarbons was effectively inhibited, and a magnetic char was generated. This work provided a promising strategy of "treating wastes with wastes" for converting oil scum to valuable gas, base oil, and magnetic char. [ABSTRACT FROM AUTHOR]

The outbreak of COVID virus resulted not only in massive human deaths but also created huge waste disposal issues. Proper disposal of COVID waste is necessary. The conversion of these wastes into value‐added products such as syngas is beneficial to overcome energy scarcity issues. The Indian high ash coal (HAC) is nonreactive, and the co‐utilisation of HAC with these plastic wastes is advantageous to produce high‐quality syngas. In the present study, thermal treatment of overall gowns (OG) used during COVID by pyrolysis and gasification process was carried out under inert and reactive conditions with and without HAC at various operating temperatures. During pyrolysis, oil with a yield of 17% was produced under N2 conditions at 900°C, whereas a reduced oxygen content in the oil was observed (absence of C–O) under CO2 conditions. The co‐gasification of OG with high ash coal in the fuel mixture resulted in the heating value of syngas as high as 8.56 MJ nm−3. The calorific value of the syngas increases by 51.8% when OG content in the fuel mixture is increased to 20% because hydrocarbon content in syngas increases by 8.73 times. Thermogravimetric analysis showed that by adding OG, gasification initiated 35°C earlier as compared to HAC. The solid residue obtained by co‐gasification contains calcium in the form of CaO and CaCO3 due to COVID‐19 waste. The global warming potential of the syngas generated is reduced by 32% with the addition of OG to 20%. [ABSTRACT FROM AUTHOR]

The utilization of biomass can not only alleviate the energy crisis but also reduce the pollution of fossil fuels to the environment. Biomass gasification is one of the main utilization methods, which can effectively convert biomass into high-value and wide-use gasification gas. However, this process inevitably produces the by-product tar, which affects the yield of syngas. In order to solve this problem, a two-stage process combining biomass pyrolysis and CO2 catalytic reforming is proposed in this paper, which is used to prepare high calorific value syngas rich in H2 and CO and reduce the by-product tar of biomass gasification while realizing the resource utilization of CO2. The effects of the reforming temperature and CO2/C ratio on the gas yield and calorific value of biomass were investigated by catalytic gasification reforming device, and the system energy consumption was analyzed. With the increase of reforming temperature, the yield of CO increased, and the yield of H2 and the calorific value of gas increased first and then decreased. Increasing the CO2/C ratio within a proper range is beneficial to the formation of syngas. When the reforming temperature is 900 °C and the CO2/C ratio is 1, syngas with a high gas calorific value is obtained, which of is 2.75 MJ/kg is obtained. At this time, the yield of H2 and CO reached the maximums, which were 0.46 Nm3/kg and 0.28 Nm3/kg, respectively. Under these conditions, the total energy consumption of the system is 0.68 MJ/kg, slightly more than 0, and does not require too much external heat. [ABSTRACT FROM AUTHOR]

During the COVID-19 pandemic, more than 24 billion pieces of surgical mask waste (WM) were generated in the EU region, with an acute shortage of their management and recycling. Pyrolysis and gasification are among the most promising treatments that were proposed to dispose of WMs and convert them into pyrolysis oil and hydrogen-rich syngas. This work aimed to investigate the techno-economic analysis (TEA) of both treatments in order to assess the feasibility of scaling up. The TEA was carried out using a discounted cash flow model and its data were collected from practical experiments conducted using a fluidised bed pyrolysis reactor and bubbling fluidised bed gasifier system with a capacity of 0.2 kg/h and 1 kg/h, respectively, then upscaling to one tonne/h. The technological evaluation was made based on the optimal conditions that could produce the maximum amount of pyrolysis oil (42.3%) and hydrogen-rich syngas (89.7%). These treatments were also compared to the incineration of WMs as a commercial solution. The discounted payback, simple payback, net present value (NPV), production cost, and internal rate of return (IRR) were the main indicators used in the economic feasibility analysis. Sensitivity analysis was performed using SimLab software with the help of Monte Carlo simulations. The results showed that the production cost of the main variables was estimated at 45.4 EUR/t (gate fee), 71.7 EUR/MWh (electricity), 30.5 EUR/MWh (heat), 356 EUR/t (oil), 221 EUR/t (gaseous), 237 EUR/t (char), and 257 EUR/t (syngas). Meanwhile, the IRR results showed that gasification (12.51%) and incineration (7.56%) have better economic performance, while pyrolysis can produce less revenue (1.73%). Based on the TEA results, it is highly recommended to use the gasification process to treat WMs, yielding higher revenue. [ABSTRACT FROM AUTHOR]

In recent years, gasification gained attention again, both as an industrial application and as a research topic. This trend has led to the necessity to understand the process and optimize reactors for various materials and configurations. In this article, the thermal structure of a counter-current reactor is investigated to demonstrate that constraints on the temperature mainly determine the oxidation and the pyrolysis region. A non-dimensional set of equations is written and numerically solved using the method of lines (MOL) with spatial discretization based on a spectral algorithm. The results show that four thermal structures can be identified, two of which are the most common ones found in reactors of practical applications. Two stationary operation positions have been determined, one in the upper and one in the lower part of the reactor. Existence and stability conditions have been discussed based on non-dimensional parameters. The knowledge derived from this analysis was applied to two configurations, one typical of a biomass gasifier and one proposed for waste gasification. [ABSTRACT FROM AUTHOR]

Biomass treatment for energy production is a promising way for achieving fossil fuel replacement and environmental relief. Thermochemical processes are a common way of processing biomass, but their potential economic benefits are not always clear to investors. In this work, three basic thermochemical processes (combustion, gasification, and pyrolysis) are examined in terms of their theoretical yields and their products, as well as their economic viability. The goal of this analysis was to look into the total amount of available biomass streams and compare business plans in terms of sustainability from a technical and economic perspective. The estimation of the fixed capital investment was based on ready−made solutions that are already available on the market. The analysis showed that the gasification unit has the optimum sustainability results since the total amount of gross income was EUR 0.13/kg of biomass while the treatment cost was estimated at EUR 0.09/kg of biomass. The internal rate of return of the investment was calculated at 9%, establishing a promising alternative solution to sustainable "green" energy production. [ABSTRACT FROM AUTHOR]

Hydrogen is considered one of the most important forms of energy for the future, as it can be generated from renewable sources and reduce CO2 emissions. In this review, the different thermochemical techniques that are currently used for the production of hydrogen from biomass from plantations or crops, as well as those from industrial or agro-industrial processes, were analyzed, such as gasification, liquefaction, and pyrolysis. In addition, the yields obtained and the reactors, reaction conditions, and catalysts used in each process are presented. Furthermore, a brief comparison between the methods is made to identify the pros and cons of current technologies. [ABSTRACT FROM AUTHOR]

In this study, biomass–specific gasification data is experimentally collected for numerical simulations of fixed–bed reactors. Since biomass properties vary, it is crucial to have characteristic biomass data. Extensive data is collected to determine an appropriate description of specific biomass behavior, including basic data (e.g., heating value, size, densities, ultimate and total analysis etc.), biomass pyrolysis and heterogeneous gasification reaction data. Heterogeneous reactions were comparatively investigated in the forms of powder, particles, and a fixed–bed. The powder was investigated in depth with CO2, O2, and H2O (gas fraction 5–20 vol.%; temperature CO2, O2 and H2O, respectively, at 730–790 °C, 360–405 °C, 720–780 °C), while particle reactions and fixed–bed reaction were only studied with CO2. A model description for a fixed–bed batch reactor was applied, modified, and compared to experimental fixed–bed batch reactor results. This study concludes that determining the appropriate characteristic particle size and parameters for the porous structure of specific biomass char is essential for simulation based on preliminary biomass characterization. Therefore, in future investigations, the description for biomass-specific differences between powder, single particles, and bulk of biomass char may be of greater focus, also taking into consideration O2 and H2O. [ABSTRACT FROM AUTHOR]

Biomass gasification to form syngas is a promising renewable energy production process. Here, biomass is exposed to high temperatures in an oxygen-controlled environment where volatiles react to form components of syngas that can be used for energy or chemical production. A limitation to the use of gasification is the generation of tars that condense in downstream equipment causing damage and halting production. Currently tars are removed by physical, thermal, or catalytic processes, all high-cost options. On the other hand, biochar is produced as a solid by-product of gasification, characterized by high surface area, desirable adsorption properties, and relatively low cost. This review details the use of biochar as a catalyst to reform tars, while highlighting recent experimental advances in evaluating the effects of biomass composition, gasification conditions, and pre-treatment and post-treatment options to improve catalytic function. It discusses tar degradation mechanisms and catalyst deactivation and recommends further areas for research. [Display omitted] • Biochar has shown good performance as a tar reforming catalyst. • Biochar properties were outlined, and modification methods were recommended. • Tar reduction and catalyst deactivation mechanisms were presented. • Methods for loading metals on biochar were compared for catalytic enhancement. • Catalyst stability was identified as an area for future investigation. [ABSTRACT FROM AUTHOR]

Seaweed can be a desirable source of renewable energy or fuel after it has been processed by combustion, thermochemical conversion by gasification, pyrolysis, or hydrothermal liquefaction (HTL) or biochemical conversion routes like anaerobic digestion (AD). This work explores how well the measured properties of seaweed pellets match the specifications for the various fuel and energy conversion options listed. Blends of hay, wood chips, sawdust, and seaweed were pelletized. Eight pellet blends with dominant seaweed content and minimum acceptable mechanical strength and stability were produced and their physical and chemical properties were reported. The seaweed pellets had an energy content of around 14 MJ/kg, and each pellet could withstand almost 200 N of compression force. Their water content was around 5% or less and their ash content was around 20–34%. According to the results, a higher wood content increased the energy content of the pellets. Among those properties measured in this project, none of them contradicted the typical specifications of combustion, HTL, and AD. However, the low water content and low strength of some pellet types were unable to meet the specifications for certain types of gasification and pyrolysis. [ABSTRACT FROM AUTHOR]

This research aims to develop a new strategy to valorize wasted COVID-19 masks based on chemical recycling by pyrolysis to convert them into useful products. First, surgical and filtering face piece masks, as defined in Europe by the EN 149 standard (FFP2), were thermally pyrolyzed at temperatures of 450, 500, and 550 °C, and the yields of valuable solid (biochar), liquid (biooil), and syngas products and their characteristics were determined. At low temperatures, biochar formation was favored over biooil and syngas production, while at high temperatures the syngas product yield was enhanced. The highest yield of biooil was found at a pyrolysis temperature of 500 °C, with both surgical and FFP2 masks achieving biooil yields of 59.08% and 58.86%, respectively. Then, the pyrolysis experiments were performed at 500 °C in a two-stage pyrolysis catalytic reactor using sepiolite as a catalyst. Sepiolite was characterized using nitrogen adsorption–desorption isotherms and Fourier-transform infrared spectroscopy. Results showed that the two-stage process increased the final yield of syngas product (43.89% against 39.52% for surgical masks and 50.53% against 39.41% for FFP2 masks). Furthermore, the composition of the biooils significantly changed, increasing the amount of 2,4-Dimethyl-1-heptene and other olefins, such as 3-Eicosene, (E)-, and 5-Eicosene, (E)-. Additionally, the methane and carbon dioxide content of the syngas product also increased in the two-stage experiments. Ultimately, the effect of sepiolite regeneration for its use in consecutive pyrolysis tests was examined. Characterization data showed that, the higher the use-regeneration of sepiolite, the higher the modification of textural properties, with mainly higher changes in its pore volume. The results indicated that the pyrolysis of face masks can be a good source of valuable products (especially from biooil and syngas products). [ABSTRACT FROM AUTHOR]

Printed circuit boards are considered a secondary source of raw materials, such as precious or base metals. One of the most promising solutions for recovering these metals is certainly hydrometallurgy. However, the leaching of different metals from PCBs is hindered by the presence of an organic fraction that lowers the extraction yields. One solution to this problem is a pyrolysis pre-treatment which removes the organic fraction and enhances it through conversion into syngas. A steady-state simulation model was developed using ASPEN PLUS to describe the thermodynamic behavior of PCB pyrolysis. The pyrolysis reactor was modeled as a combination of the Yields reactor and the Gibbs reactor. The model has been validated using various data present in the literature. The composition of the different products was estimated through the minimization of Gibbs's free energy. A sensitivity analysis was performed to investigate the influence of different parameters on the conversion yield and the syngas quality produced. Thanks to the study, it was possible to describe and analyze the pyrolysis of PCBs without requiring numerous experimental tests. The results show how steam gasification appears to be the most efficient technology for the pre-treatment of PCBs within a hydrometallurgical process. [ABSTRACT FROM AUTHOR]

A compartmental one‐dimensional model of a fluidized bed pyrolytic converter of biomass is presented. Reference conditions are those of non‐catalytic fast pyrolysis of biomass in a shallow fluidized bed with external regeneration of the bed material. The fate of biomass and of the resulting char has been modelled by considering elutriation of biomass and char particles, char attrition as well as bed drain/regeneration. The course of primary and secondary pyrolitic reactions is modelled according to a semi‐lumped reaction network using well‐established kinetic parameters taken from the literature. A specific focus of the present study is the role of the heterogeneous volatile–char secondary reactions, whose rate has been modelled by borrowing a kinetic expression from the neighbouring area of tar adsorption/decomposition over char. The results of computations highlight the relevance of heterogeneous volatile–char secondary reactions and of the closely associated control of char loading in the bed. The sensitivity of the reactor performance to char elutriation and attrition, to proper management of bed drain/regeneration, and to control of gas phase backmixing is demonstrated. Model results provide useful guidelines for optimal design and control of fluidized bed pyrolyzers and pinpoint future research priorities. [ABSTRACT FROM AUTHOR]

To reveal the effect of torrefaction pretreatment on pyrolysis and gasification reactivity of biomass, corn cob was first subjected to torrefaction pretreatment in a fixed-bed reactor at various reaction temperatures. The pyrolysis reactivity, kinetics, and gasification reactivity of torrefied corn cob were systematically assessed by various methods, proving that torrefaction pretreatment has a substantial influence on the physicochemical properties of corn cobs. The O/C and H/C molar ratios of corn cobs considerably drop with the increasing torrefaction temperature, and their higher heat-ing value (HHV) and energy density rise as well. It is found that torrefaction improves the pyrolysis reactivity of corn cobs because hemicellulose degradation is more severe than cellulose degradation during torrefaction, resulting in an increase in the percentage of cellulose in torrefied corn cobs. However, the severe depolymerization, polycondensation, and carbonization reaction during torre-faction of corn cobs at 280–300 °C can lead to a significant decline in the pyrolysis reactivity of corn cobs. Torrefaction pretreatment increases the pyrolysis activation energy of corn cobs, in addition to decreasing the char gasification reactivity of corn cob. The average char gasification reactivity of corn cobs drops when torrefaction severity increases. The passivation of active sites on the char surface may cause condensation and carbonation reactions of corn cobs during torrefaction. These findings provide new sights into the reasonable design of efficient torrefaction methods for appli-cation prior to pyrolysis and gasification of biomass. [ABSTRACT FROM AUTHOR]