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CaO modified with acetic acid solution or sodium hydroxide (H-CaO/OH-CaO) was used to explore the relationship between the physical and chemical properties of CaO and the components of bio-oil during the pyrolysis of rice straw (RS) and model compounds via experiment and density functional theory(DFT) simulation. The results showed that the modification changed the properties of CaO, and thus the catalytic performance on production of bio-oil components. H-CaO with the larger number of strong basic sites (1.10 ∼ 2 times than commercial CaO) and the longer Ca-O bond length showed the better selectivity and performance on formation of ketones (the maximum relative content in bio-oil reached 43 %). The conversion pathway of cellulose/hemicellulose was changed by H-CaO, which promoted the formation of ketones. The easier combining of H-CaO with the pyrolysis primary products due to the longer Ca-O bond was the key to its better performance., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

A variety of machine learning (ML) models have been extensively utilized in predicting biomass pyrolysis owing to their prowess in deciphering complex non-linear relationships between inputs and outputs, but there is still a lack of consensus on the optimal methods. This study elaborates on the development, optimization, and evaluation of three ML methodologies, namely, artificial neural networks, random forest (RF), and support vector machines, aimed to determine the optimal model for accurate prediction of biomass pyrolysis behavior using thermogravimetric data. This work assesses the utility of thermal data derived from these models in the computation of kinetic and thermodynamic parameters, alongside an analysis of their statistical performance. Eventually, the RF model exhibits superior physical interpretability and the least discrepancy in predicting kinetic and thermodynamic parameters. Furthermore, a feature importance analysis conducted within the RF model framework quantitatively reveals that temperature and heating rate account for 98.5 % and 1.5 %, respectively., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Biomass is regarded as the only carbon-containing renewable energy source and has performed an increasingly important role in the gradual substitution of conventional fossil energy, which also contributes to the goals of carbon neutrality. In the past decade, the academic field has paid much greater attention to the development of biomass pyrolysis technologies. However, most biomass conversion technologies mainly derive from the fossil fuel industry, and it must be noticed that the large element component difference between biomass and traditional fossil fuels. Thus, it's necessary to develop biomass directional pyrolysis technology based on the unique element distribution of biomass for realizing enrichment target element (i.e., element economy). This article provides a broad review of biomass directional pyrolysis to produce high-quality fuels, chemicals, and carbon materials based on element economy. The C (carbon) element economy of biomass pyrolysis is realized by the production of high-performance carbon materials from different carbon sources. For efficient H (hydrogen) element utilization, high-value hydrocarbons could be obtained by the co-pyrolysis or catalytic pyrolysis of biomass and cheap hydrogen source. For improving the O (oxygen) element economy, different from the traditional hydrodeoxygenation (HDO) process, the high content of O in biomass would also become an advantage because biomass is an appropriate raw material for producing oxygenated liquid additives. Based on the N (nitrogen) element economy, the recent studies on preparing N-containing chemicals (or N-rich carbon materials) are reviewed. Moreover, the feasibility of the biomass poly-generation industrialization and the suitable process for different types of target products are also mentioned. Moreover, the enviro-economic assessment of representative biomass pyrolysis technologies is analyzed. Finally, the brief challenges and perspectives of biomass pyrolysis are provided., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

This study predicts pyrolytic product yields via machine learning algorithms from biomass physicochemical characteristics and pyrolysis conditions. Random forest (RF), gradient boosting decision tree (GBDT), eXtreme Gradient Boosting (XGBoost), and Adaptive Boost (Adaboost) algorithms are comparatively analyzed. Among these algorithms, the RF algorithm is the best modeling algorithm and performs best in predicting the bio-oil yield and performs well in predicting biochar and pyrolytic gas yields. The moisture content, carbon content, and final heating temperature are the most important factors in predicting pyrolysis product yields, and biomass characteristics are more important than pyrolysis conditions. Furthermore, the carbon content positively affects the bio-oil yield and negatively affects the biochar yield, and the final temperature positively affects the pyrolytic gas yield and negatively affects the biochar yield. This work provides new insight for controlling the yields of pyrolytic products via the RF algorithm, which can facilitate the process optimization in engineering applications., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Biochar-derived dissolved organic carbon (BDOC) and smoke-derived dissolved organic carbon (SDOC) are two different biomass-pyrogenic DOCs. They inevitably enter soil and water, then potentially pose different impacts on the chemistry of these media. This study systemically investigated the emissions and spectral characteristics of BDOC and SDOC as well as their differences from natural DOC. The results showed that the emission of SDOC was 1-3 orders of magnitude greater than that of BDOC after biomass pyrolysis. UV-vis spectra indicated that BDOC had higher aromaticity and molecular weight as well as lower polarity than SDOC. The two-dimensional correlation infrared spectrum (2D-PCIS) matrix indicated that BDOC contained more chemical groups with stronger temperature-dependence than SDOC. Fluorescence EEM-PARAFAC analysis showed that BDOC was dominated by macromolecular humic-like substances, while SDOC was primarily composed of small molecules of aromatic protein/polyphenols-like compounds. The fluorescence indicators including humification index (HIX) (0.08-0.76) and biological index (BIX) (1.18-1.72) of SDOC were significantly different from those of BDOC (HIX: 1.64-12.68, and BIX: 0.17-1.62). The higher BIX and more small molecules of aromatic protein/polyphenols-like compounds indicated SDOC had potentially higher bioavailability and turnover rate in the environment than BDOC. Furthermore, the UV-vis spectral indicator (S 275-295 ) and fluorescence spectral indicators (HIX, and BIX) of BDOC were equivalent to those of natural DOC, whereas these indicators of SDOC were significantly different from those of natural DOC. This study demonstrated that BDOC and SDOC had significantly different components and properties and they might present different environmental behaviors and effects., (Copyright © 2022. Published by Elsevier Ltd.)

The harm done to the environment by fossil fuels was serious, and it is urgent to find effective methods and adopt carbon-neutral feedstock to prevent further environmental damage. An innovative infrared heating reactor was developed for the generation of high-yield bio-oil and cleaner pyrolysis gases. This work was devoted to exploring the fast pyrolysis characteristics and its mechanism of corn stover over the iron oxide in a novel infrared heating (IH) reactor and a traditional electric heating (EH) reactor. In the IH reactor, the bio-oil yield increased initially and then decreased with increasing pyrolysis temperature, reaching a maximum yield of 29 wt% at 600 °C. The yield of pyrolysis bio-oil and water decreased as the reusability number rose, whereas the char yield increased. Bio-oil yields decreased less from R0 to R3 and the catalyst was more effective in IH. IH produced more char and gas but considerably less water than EH, and its bio-oil had fewer phenols. Raman spectroscopy demonstrated that the aromatic structure of biochar increased as the pyrolysis temperature increased. Cellulose and hemicellulose can be completely cleaved at lower temperatures in IH. In addition, Fe 2 O 3 catalysts have shown the advantages of low cost, efficient cycling, and long action time. Infrared heating coupled with iron oxide catalyst shows the potential to increase bio-oil yield and is more promising for industrial production than EH., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The effect of heat exchange area on the componential evolutions of biomass pyrolysis vapors was visualized through an innovative combining method of bio-oil composition inversion and function fitting. As the maximal diameter of condenser at 340 K increased from 35 mm to 55 mm, the fitted heat maps showed that the recovery of organics increased in the top of condenser and remained steady in the bottom, whereas the water recovery only increased in the top but decreased in the bottom. The recovery proportion of furfural and phenolic compounds increased by 20-40% with unvaried water recovery, and the content enrichment of high value-added components increased by 30-45% at 37 wt% of bio-oil yield. Heat exchange area exhibited a finer regulation effect on the condensation of pyrolysis vapors than traditional condensing adjustment methods, which first provided a remarkable promotion for the recovery and enrichment of organic components without improving water recovery., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

This study aimed to utilize machine learning algorithems combined with feature reduction for predicting pyrolytic gas yield and compositions based on pyrolysis conditions and biomass characteristics. To this end, random forest (RF) and support vector machine (SVM) was introduced and compared. The results suggested that six features were adequate to accurately forecast (R 2  > 0.85, RMSE < 5.7%) the yield while the compositions only required three. Moreover, the profound information behind the models was extracted. The relative contribution of pyrolysis conditions was higher than that of biomass characteristics for yield (55%), CO 2 (73%), and H 2 (81%), which was inverse for CO (12%) and CH 4 (38%). Furthermore, partial dependence analysis quantified the effects of both reduced features and their interactions exerted on pyrolysis process. This study provided references for pyrolytic gas production and upgrading in a more convenient manner with fewer features and extended the knowledge into the biomass pyrolysis process., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

A novel experimental method based on the combination of bio-oil composition inversion and function fitting was purposed and verified for describing the componential evolution curves during the liquefaction of biomass pyrolysis vapors. The evolution curves of representative condensable components were fitted by linear and Slogistic function in the short, middle and long three condensing fields. Linear function exhibited a significant effectiveness for the description and prediction of low-boiling water and furfural and the relative deviations were no more than 5% between actual values in long condenser and predictive values from the elongation of curves in short and middle condensers. For high-boiling phenolic compounds, linear function failed to fit their evolutions in long condenser but Slogistic fitting remained effective despite the relative deviation increasing to about 10%. This investigation provided a unique and effective prediction method for the vapor evolution in industrial shell and tube heat exchanger according to laboratory-scale experiment., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

This study was devoted to proposing an effective experimental method based on bio-oil composition inversion for understanding biomass pyrolysis vapor evolution in four-staged condensers. The effective length of each condenser was 200 mm. The evolution curves and heat maps of condensable vapors in the whole multi-staged condensing field were provided by Logistics model fitting. With changing condition from "365-345-325-305" to "345-325-305-285", the condensing efficiency of the first condenser increased by 100% but that of the third condenser decreased by 80%. Under condition "365-345-325-305", the largest recovery rate of water was observed at 400 mm away from multi-staged condensing field entrance while that of eugenol was observed at 50 mm away from the entrance, which explained that water was primarily recovered by the second and third condensers whereas eugenol was recovered by the first condenser, and verified the remarkable effect of fractional condensation on the separation of water and high-boiling phenols., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Surface area and porosity are important physical properties of biochar, playing a crucial role in many biochar applications, such as wastewater treatment and soil remediation. The production of engineered biochar with highly porous structure and large surface area has received extensive attention. This paper comprehensively reviewed the effects of biomass and pyrolysis parameters on the surface area and porosity of biochar. The composition of biomass feedstock and pyrolysis temperature are the major influencing factors. It is suggested that the lignocellulosic biomass is an outstanding candidate, wood and woody biomass in particular. Besides, moderate temperatures (400-700 °C) are suitable for the development of the pore structure. Further improvement can be implemented by additional treatments. Activation is the most widely used and effective way to promote biochar surface area and porosity, especially the chemical activation. Enhancement can also be achieved by using other treatment methods, such as carbonaceous materials coating, ball milling, and templating. Future research should focus on upgrading or developing treatment technology to achieve enhanced functionality and porous structure of biochar simultaneously., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The alkaline-earth-metal (AEM) has a good performance on modification of both bio-oil and biochar during biomass pyrolysis. In this work, the pyrolysis of rice husk (RH) in the presence of CaO, CaCO 3 , MgO and MgCO 3 was comparatively studied for selecting an appropriate AEM additive to balance the qualities of pyrolytic products. Pyrolysis of RH with the AEM additives could decrease the acids content and increase the hydrocarbons content in bio-oil. Compared with the Ca-additives (i.e., CaO, CaCO 3 ), the Mg-additives (i.e., MgO, MgCO 3 ) were more beneficial for enhancing the hydrocarbons production. The addition of biochar to soil can significantly enhance the water retention. RHC-MgCO 3 had a maximum water retention capacity, while RHC-MgO had a minimum water retention capacity due to its lowest specific surface area. Additionally, the Mg-modified biochar had a much higher nutrient (i.e., K + , PO 4 3- ) adsorption capacity. In particular, RHC-MgO with a lowest specific surface area had a highest PO 4 3- adsorption capacity, which was evidenced by the adsorption of PO 4 3- would be an appropriate candidate that is used in pyrolysis of biomass for co-production of bio-oil and biochar composite with high capacities of water/nutrient adsorption and retention for soil amendment.4 3- adsorbed in the RHC-MgO released rapidly indicating its low PO 4 3- retention capacity. In general, MgCO 3 would be an appropriate candidate that is used in pyrolysis of biomass for co-production of bio-oil and biochar composite with high capacities of water/nutrient adsorption and retention for soil amendment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The experiments on bio-oil recovery in a vertical tubular condenser with two flumes were conducted for speculating the componential distribution of walnut shell pyrolysis vapors during condensation. Bio-oil elements and functional groups from different locations of condenser were compared with each other. Aromatic H and H in phenolic OH were concentrated in the top and middle bio-oil and their percentage were improved with increasing water bath temperature. Ten representative compounds in bio-oil were chosen for quantitative analysis. As water bath temperature increased from 273 K to 353 K, the recovered water decreased by 85% whereas the guaiacol and its derivatives (guaiacols) merely decreased by 40%. Vapor distributions of water, acetic acid, furfural and guaiacols were simulated by the back analysis of bio-oil components. According to the simulated results, tubular condenser can be properly lengthened for promoting the recovery of specific components at high water bath temperatures., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Pyrolysis of human feces renders the waste free of pathogens and is a potential method of treating fecal sludge waste collected from non-sewered systems. Slow pyrolysis experiments were conducted on human feces and the char yield and gas evolution quantified at 1-10 °C/min heating rates. Char yield ranged from 35.1 to 35.8% (dry mass basis), while the gas yield ranged from 17.2 to 29.6% (dry mass basis). The pyrolysis gases detected were CO, CO 2 , CH 4 , C 2 H 6 , and H 2 . These non-condensable gases contained a higher heating value (HHV) ranging from 7.2 to 22.8 MJ/Nm 3 . Kinetic analysis was done by a pyrolysis reaction model free method (Isoconversional) as well as a DAEM (Distributed Activated Energy Model) method that assumes many irreversible first order reactions. Both yielded very close values for activation energy ranging from 141 kJ/mol to 409 kJ/mol, with half of the biomass conversion happening at 241.5 ± 2.9 kJ/mol. The findings of the research provide useful technical information that can guide the design of a pyrolysis system to treat fecal waste. Social acceptance and scale-up issues need to be addressed through further research., (Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Biomass can be converted into energy/fuel by different techniques, such as pyrolysis, gasification, and others. In the case of pyrolysis, biomass can be converted into a crude bio-oil around 50–75% yield. However, the direct use of this crude bio-oil is impractical due to its high content of oxygenated compounds, which provide inferior properties compared to those of fossil-derived bio-oil, such as petroleum. Consequently, bio-oil needs to be upgraded by physical processes (filtration, emulsification, among others) and/or chemical processes (esterification, cracking, hydrodeoxygenation, among others). In contrast, hydrodeoxygenation (HDO) can effectively increase the calorific value and improve the acidity and viscosity of bio-oils through reaction pathways such as cracking, decarbonylation, decarboxylation, hydrocracking, hydrodeoxygenation, and hydrogenation, where catalysts play a crucial role. This article first focuses on the general aspects of biomass, subsequent bio-oil production, its properties, and the various methods of upgrading pyrolytic bio-oil to improve its calorific value, pH, viscosity, degree of deoxygenation (DOD), and other attributes. Secondly, particular emphasis is placed on the process of converting model molecules and bio-oil via HDO using catalysts based on nickel and nickel combined with other active elements. Through these phases, readers can gain a deeper understanding of the HDO process and the reaction mechanisms involved. Finally, the different equipment used to obtain an improved HDO product from bio-oil is discussed, providing valuable insights for the practical application of this reaction in pyrolysis bio-oil production. [ABSTRACT FROM AUTHOR]

Acetylene is produced from the reaction between calcium carbide (CaC2) and water, while the production of CaC2 generates significant amount of carbon dioxide not only because it is an energy-intensive process but also the raw material for CaC2 synthesis is from coal. Here, a comprehensive biomass-to-acetylene process was constructed that integrated several units including biomass pyrolysis, oxygen-thermal CaC2 fabrication and calcium looping. For comparison, a coal-to-acetylene process was also established by using coal as feedstock. The carbon efficiency, energy efficiency and environmental impacts of the bio-based calcium carbide acetylene (BCCA) and coal-based calcium carbide acetylene (CCCA) processes were systematically analyzed. Moreover, the environmental impacts were further evaluated by applying thermal integration at system level and energy substitution in CaC2 furnace. Even though the BCCA process showed lower carbon efficiency and energy efficiency than that of the CCCA process, life cycle assessment demonstrated the BCCA (1.873 kgCO2eq kg-prod−1) a lower carbon footprint process which is 0.366 kgCO2eq kg-prod−1 lower compared to the CCCA process. With sustainable energy (biomass power) substitution in CaC2 furnace, an even lower GWP value of 1.377 kgCO2eq kg-prod−1 can be achieved in BCCA process. This work performed a systematic analysis on integrating biomass into industrial acetylene production, and revealed the positive role of biomass as raw material (carbon) and energy supplier. [ABSTRACT FROM AUTHOR]

The understanding of complex fluidization hydrodynamics and chemical reactions in biomass fast pyrolysis fluidized bed reactors is lacking and requires further investigation. It is urgent to develop accurate mathematical models capable of describing the complex multiphase reaction system of biomass pyrolysis. A comprehensive multiscale model based on coarse‐grained discrete element method (DEM)‐computational fluid dynamics (CFD) was developed in open‐source MFiX code. It incorporates detailed biomass pyrolysis kinetics and an intraparticle model. To validate the model, measurements were conducted in a fluidized bed pyrolyzer, including quantifying the segmental pressure drop along the height of the bed and determining the yields and compositions of gas, liquid, and solid products. The particle mixing and segregation, axial distribution and residence time, Lacey index, and pyrolysis products were investigated. The study provides experimental and theoretical foundations for designing multiphase fluidized bed reactors and advancing biomass thermochemical conversion. [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]

A series of boron-promoted Ni-Co/Ca catalysts were synthesized by the sol–gel method to enhance syngas generation from biomass pyrolysis. The efficiency of these catalysts was evaluated during the pyrolysis of rice straw in a fixed-bed reactor, varying the Ni/Co ratio, boron addition, calcination temperature, and residence time. The catalysts underwent comprehensive characterization using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) analysis, scanning electron microscopy (SEM), and hydrogen temperature-programmed reduction (H2-TPR). The results indicated that the Ni-Co/Ca catalysts yielded superior syngas compared to singular Ni or Co catalysts, suggesting a synergistic interplay between nickel and cobalt. The incorporation of 4% boron significantly decreased the particle size of the active metals, enhancing both the catalytic activity and stability. Optimal syngas production was achieved under the following conditions: a biomass-to-catalyst mass ratio of 2:1, a Ni-Co ratio of 1:1, a calcination temperature of 400 °C, a pyrolysis temperature of 800 °C, and a 20 min residence time. These conditions led to a syngas yield of 431.8 mL/g, a 131.28% increase over the non-catalytic pyrolysis yield of 188.6 mL/g. This study not only demonstrates the potential of Ni-Co/Ca catalysts in biomass pyrolysis for syngas production but also provides a foundation for future catalyst performance optimization. [ABSTRACT FROM AUTHOR]

The development of biomass pyrolysis technology is important for alleviating energy shortages and environmental pollution. To investigate the generation trends in three-phase products, biomass pyrolysis experiments at different temperatures were carried out using a tubular furnace. The results showed that hemicellulose and cellulose structures began to dehydrate and break down and that alkyl-aryl lignin began to decompose between 200 ℃ and 400 ℃. After the temperature reached 400 °C, C O functional groups in the biochar began to decline, and a part of the biochar was converted into CO. After the temperature reached 500 °C, the biochar gradually formed a complex fused-ring structure. The tar yield increased first and then decreased with increasing pyrolysis temperature, reaching a maximum (32.82%) at 700 °C. On the one hand, tar generation occurred due to the biomass pyrolysis reaction, mainly at temperatures below 500 ℃. On the other hand, it occurred due to the homogeneous transformation reaction of tar, mainly above 500 ℃. The maximum value of the H 2 release curve increased with increasing temperature, and its change was most obvious relative to that of the other gases. The formation of H 2 at higher temperatures was mainly due to dehydrogenation, condensation and polycondensation reactions. [ABSTRACT FROM AUTHOR]

[Objective] The extensive combustion of fossil fuels results in increasingly severe environmental pollution, greenhouse gas emissions, and other related challenges. As a result, it is imperative to vigorously advance the development and utilization of renewable energy sources to foster clean and efficient energy utilization. As a promising green technology, biomass pyrolysis driven by concentrated solar energy will optimize the usage and storage of renewable energy. By harnessing solar radiation as a heat source for biomass pyrolysis reactions, it produces high-quality syngas, bio-oil and bio-char, consequently creating an opportunity to integrate solar energy into the broader energy system, catering to diverse needs. However, challenges arise owing to the fluctuating radiation intensity and complex chemical processes involved in the solar-driven pyrolysis reaction. Understanding the release patterns of biomass pyrolysis products, under different radiant flux densities becomes crucial for exploring the influence characteristics of radiation on dynamic pyrolysis energetic and chemical transformation processes. To thoroughly investigate the dynamic generation rules and benefits associated with the solar pyrolysis products of straw biomass, we have designed and constructed a specialized experimental platform. This platform is specifically tailored for direct biomass pyrolysis powered by high-flux concentrated solar energy. [Methods] A high-energy flow solar simulator is used to generate simulated solar rays. These rays, produced by several xenon lamps, are reflected through an ellipsoidal mirror and concentrated on the reaction bed. This process creates a high-temperature, high-radiation environment. We use a newly designed thermochemical reactor to drive biomass pyrolysis. We monitor the dynamic reaction process with a gas pretreatment system and an online gas analyzer. To ensure clarity in our experimental conditions, we adopt a grayscale method based on a "Lambert target + CCD camera" system, which indirectly measures the distribution characteristics of radiant energy density. Additionally, we strategically place thermocouples throughout the reaction space to monitor temperature characteristics. We use wheat straw as the biomass sample to investigate the characteristics of solar-driven pyrolysis under different energy flux densities. [Results] The solar simulator of our experiment generated a high-temperature spot with an average energy flux density of 757 kW/m² at an electric power of 6.0 kW. This achieved maximum temperatures and pyrolysis reaction heating rates of 870 °C and 25 °C/s, respectively. Our results reveal that increasing the radiation intensity of the light source enhances the release of pyrolysis products H2 and CO. By increasing the electric power of the solar simulator from 1.5 kW to 6.0 kW, the yields of H2 and CO increased by 13.8% and 18.0%, respectively. Furthermore, the peak times for CO and H2 concentrations in pyrolysis gas were reduced by 67% and 71%, respectively. This suggests that augmenting the radiation intensity significantly accelerates biomass pyrolysis reactions. Moreover, the peak concentration levels of H2 rose to 11.48% from 1.49%, and the CO peak concentration increased to 11.61% from 1.59%, indicating a substantial enhancement in pyrolysis reaction rate. [Conclusions] Our research provides valuable insights into the efficient solar-driven pyrolysis conversion of straw biomass and the rational design of solar reactors. [ABSTRACT FROM AUTHOR]

Recently, salt-assisted pyrolyzation has been deemed an emerging and efficient method for the preparation of biochars due to its facile operation as well as its good structural and chemical properties. In this work, biochars (MBCx) are prepared by heating bamboo powders in eutectic salts (Li2CO3 + K2CO3) at 500–600 °C in the air. Multiple technologies are employed to examine the physiochemical properties of bamboo biochars. Correlations between heating temperature and structural features and carbon dioxide uptakes of bamboo biochars have been investigated. The results show that heating temperature has a significant influence on the physicochemical properties of bamboo biochars. With the elevation of the heating temperature, the defect structures of bamboo biochars gradually ascend, especially when the heating temperature reaches 600 °C. MBCx biochars visibly exceed conventional bamboo biochar prepared via pyrolyzation in a nitrogen stream free of salt addition. Pyrolysis of bamboo in eutectic salts endows biochars with higher oxygen content and more carbon defects, which likely accounts for their better CO2 capture activities. [ABSTRACT FROM AUTHOR]

Spent lithium-ion batteries rich in transition metals are highly potential to catalyze the biomass pyrolysis process. This research provided insight into the performance and mechanism of ex - situ catalytic upgrading of biomass pyrolysis volatiles over the thermally pyrolyzed spent Ni–Co–Mn ternary batteries (PyNCM) for the first time. The results showed that the PyNCM exhibited high catalytic activities for the secondary decompositions of pyrolysis volatiles, resulting in 12.6% reduction on bio-oil yield and 57.5% promotion on syngas productivity. The magnetic Ni and Co compounds in PyNCM were primarily responsible for the enhanced volatile deoxygenations, and the maximum H 2 yield reached 2.66 mmol g−1 biomass. Two levels of synergistic catalysis were identified: (1) the synergy among the transition metals established multiple active centers to promote the H 2 selectivity; (2) the non-magnetic graphite and lithium could probably improve the dispersion and surface oxygen vacancies of nickel and cobalt to further enhance the catalytic activity. [Display omitted] • Concentrations of O-species were notably reduced by 31.7% with PyNCM. • The catalysis of PyNCM could be enhanced via raising the reforming temperature. • Maximum CO and H 2 yields achieved 4.02 and 2.66 mmol g−1 biomass at 650 °C. • Magnetic Ni and Co were primarily responsible for the catalytic activity. • Two levels of synergistic effects were identified within the PyNCM constituents. [ABSTRACT FROM AUTHOR]

This work focused on investigating the pyrolysis characteristics of sorghum stalk (SS) and reed stalk (RS), whose potentiality as value-added feedstocks for thermochemical conversion is largely unexplored. The experimental method, thermogravimetric-infrared-mass spectrometry, was applied to reveal the thermal decomposition process, evaluate the kinetic and thermodynamic parameters, and identify the gaseous products, which could provide fundamental data and valuable information for bioenergy utilization and optimization of reactors. The average activation energy values of SS and RS by isoconversional methods are estimated to be 185.0–210.4 kJ/mol and 192.6–197.0 kJ/mol. Though kinetic parameters, especially activation energy values, play a crucial role in understanding reaction mechanism and guiding further applications, conventional methods are time-consuming and labor-intensive. In the current work, a gradient boosting regression tree model was successfully constructed to achieve fast prediction of activation energy values with a competitive accuracy of R2 > 0.85 without repetitive experiments. In addition, the established model has showed good generalization ability in new datasets, which reveals the great potential of the machine learning approach in the pyrolysis kinetic field. [Display omitted] • A detailed study on pyrolysis behavior of sorghum and reed stalk by TG/IR/MS. • Kinetic triplets and main gaseous products of biomass pyrolysis were reported. • Gradient boosting regression obtained the E α prediction performance of R2 > 0.85. • Partial dependency analysis provided insights into the ensemble algorithm. [ABSTRACT FROM AUTHOR]

The present work elaborates on the simulation and techno-economic analysis of a proposed MW-scale hybrid scheme that enables the production of different marketable products (i.e., electric energy and bio-oil) from the thermochemical exploitation of olive kernel residual biomass. In this regard, detailed calculations for mass and energy balances, process simulation in Aspen Plus and economic analysis with complementary sensitivity scenarios were conducted, with the aim to model and assses the feasibility of an integrated process for electricity and crude bio-oil co-generation via subsequent stages of biomass pyrolysis, bio-char gasification, syngas-fed SOFC and steam turbine. Notably, it was demonstrated that the provision of 20 tn/day of raw olive kernel resulted in a net electricity generation of 1685 kW el as well as production of 3.4 tn/day of bio-oil, without the need for external heating. Equally importantly, the overall electric efficiency and the combined bio-oil/power co-generation efficiency of the integrated process were equal to 46.8% and 77.0%, respectively, being amongst the highest values reported in relevant works. Moreover, economic analysis revealed that syngas clean-up and SOFC units account for 75% of the total fixed capital investment as well as for 62% of the annual operation costs. Nonetheless, increased unit cost is largely counterbalanced by the fact that electricity generation accounts for ∼85% of total profits. Also, it was found that the proposed venture is not profitable considering current market values for electricity and bio-oil. However, sensitivity analysis revealed that a main equipment cost reduction of 70% is a prerequisite for the break-even electricity price to attain the current market values. Moreover, profitability can be marginally improved further by accounting for a state subsidization of more than half of the initial investment and by the increase of the crude bio-oil price at 700 €/tn. • Simulation of a biomass co-generation process (1.68 MW el , 140 kg bio-oil/h). • Net electrical and overall efficiency of 47% and 77%, respectively. • SOFC and syngas clean-up units account for 3/4 of total equipment cost. • High break-even price for electricity between 0.890 and 0.915 €/kWh. • Competitive electricity price for 50% MEC reduction and CAPEX subsidy. [ABSTRACT FROM AUTHOR]

A sequential two-step thermochemical process was studied for spent green tea waste (SGTW), involving an initial pyrolysis step followed by thermal or catalytic cracking. This process was carried out in two bench-scale reactors (fixed bed reactor and tubular reactor) serially coupled. At a fixed pyrolysis temperature of SGTW (550 °C), the application of high cracking temperatures (700 and 800 °C) positively affected both the yield and composition of the gas product. Consequently, it has the potential to be used for the production of diverse biofuels and chemicals, or to be partially recycled to optimize the process efficiency. Moreover, the use of inexpensive catalysts, particularly dolomite, was considered advantageous, since the syngas yield (56.5 wt%) and its potential were greatly enhanced, reaching a H2/CO ratio of 1.5. The homogenous biochar obtained, with a calorific value of 26.84 MJ/kg, could be harnessed as good-quality fuel for briquette applications and as a biofuel source for generating stationary power. Furthermore, catalytic cracking pyrolysis was examined for different types of coffee waste, revealing that this process is a simple and clean solution to valorize oxygen-rich lignocellulosic biomass and generate valuable gaseous by-products. [ABSTRACT FROM AUTHOR]

Regulation of operating parameters is crucial in biomass pyrolysis polygeneration. A two-stage reaction system was used to investigate the biochar catalytic reforming of corn straw pyrolysis tar. The effects of pyrolysis temperature (500 °C–800 °C), catalytic temperature (600 °C–750 °C) and steam content (0 vol%∼40 vol%) were studied and analyzed. GC-MS, Raman, FTIR, N 2 adsorption and TG were used in the analysis of tar and biochar. The most suitable operating parameters were finally determined, namely, pyrolysis temperature of 800 °C, catalytic temperature of 700 °C and addition of 30 vol% steam. With these parameter settings, tar is almost completely removed, and the H 2 yield reaches the highest 0.197 L/g. As the pyrolysis temperature increases, the tar yield decreases continuously and the yields of CH 4 , CO and H 2 increase significantly. 600 °C–700 °C is the preferred catalytic temperature range for biochar, and 650 °C is the most suitable catalytic temperature for biochar, at which the tar yield is reduced to 0.15%. The H 2 yield gradually increases with increasing catalytic temperature, while the CH 4 and CO yields reach their highest values at 700 °C. The addition of steam reduces the tar yield to a much lower level and its value is no longer available by laboratory methods. Styrene, Indene and Naphthalene are completely converted. When 30 vol%∼40 vol% of steam is added, the Toluene peak area drops to less than 30% of that without steam. The addition of steam also promotes the methane steam reforming and the water-gas shift reaction. The H 2 yield is significantly increased. [Display omitted] [ABSTRACT FROM AUTHOR]

Pyrolysis oils with different effective hydrogen (H/C eff) ratios are mixed with tetralin at a mass ratio of 1:1 and treated at 400 °C for 2 h under 6 MPa H 2 over Pt/C and Ru/C, respectively, to examine the effect of H/C eff ratio on the yield and quality of the upgraded oil. Pyrolysis oil with higher H/C eff ratios results in an upgraded oil with higher yield and H/C eff ratios. The highest S and O reduction ratios of 96.11% and 56.26% are achieved with added Pt/C at an H/C eff ratio of 1.39 of the feedstock. In comparison, the highest N reduction ratios of 34.50% is achieved with added Ru/C at an H/C eff ratio of 1.38 of the feedstock. The N and S poison the catalyst's active sites and reduce the deoxygenation efficiency. Thus, we view that the H/C eff plays a vital role in improving the properties of the bio-oil. • Effective hydrogen significantly affected the yield and quality of the pyrolysis oil. • Higher effective hydrogen of biomass resulted in pyrolysis oil with higher effective hydrogen. • Higher effective hydrogen of pyrolysis oil resulted in upgraded oil with higher effective hydrogen. • The presence of N in the pyrolysis oil impaired the O and S removal from the pyrolysis oil. • Better performance of platinum than ruthenium was observed toward the N, O, and S removal. [ABSTRACT FROM AUTHOR]

Biomass pyrolysis is a promising route for synthesizing graphene-like carbon (GLC) structures, potentially offering a cost-effective and renewable alternative to graphene. This review paper responds to the call for highlighting the state of the art in GLC materials design and synthesis from renewable biomass microwave pyrolysis. This paper includes an introduction of the microwave pyrolysis technology, information on feedstock variability and selection, discussion on the correlation between microwave pyrolysis process conditions and pyrolyzed product characteristics, and, more importantly, a section identifying any differences between pyrolyzing feedstock using the microwave pyrolysis method vs. conventional pyrolysis method. Furthermore, this work concludes by detailing the knowledge currently missing with the recommendation for future research/innovation directions. [ABSTRACT FROM AUTHOR]

Biomass pyrolysis is typically modeled based on the three reference components cellulose, hemicellulose, and lignin. Most models rely on an individual decomposition of the materials and a linear superposition of the individual component products weighted by the present mass fractions. Models of varying complexity exist for the mathematical description of the pyrolysis process, ranging from the simplest single first-order (SFOR) model and the multi-step CRECK model to the chemical percolation devolatilization (CPD) model representing the molecular network of the solid. The models differ not only in their complexity but also in the used data for initial parameter calibration — thermogravimetric analysis (TGA) data for the CRECK model and mainly entrained flow, fluidized bed, or wire mesh reactor data for the Bio-CPD model. Within the present study, the predictive performance of these three models is compared with regard to the time-dependent total volatile release and the final volatile yield when applying two different thermal boundary conditions: low heating rate in a TGA and flash pyrolysis conditions realized with a small-scale fluidized bed reactor (FBR). The models are compared with one other and with experimental data on extracted, separately pyrolyzed biomass components to examine under which conditions reliable predictions can be made and when the trustability is limited. For the TGA data, the CRECK model has the closest proximity to the experimental measurements, also resolving most of the individual reactions, while the SFOR model can resolve only one globally dominating reaction, and the Bio-CPD model strongly overpredicts the reactivity of the biomass components during the slow heat-up. Under flash pyrolysis conditions in the FBR, by contrast, the Bio-CPD model predictions are closest to the experimental results when it comes to predicting the total volatile release rate. However, examining the integrally released yields, the CRECK model is closer to the experiments. Regarding the tar and light gas distribution, all models strongly overpredict tar from primary pyrolysis compared to the experimental results, indicating the presence of secondary gas-phase reactions in the FBR. Although different secondary gas-phase reaction models are used, the tar yield is significantly overestimated by the models compared to the experimental data. • First model comparison (CRECK vs. Bio-CPD) for extracted biomass components. • CRECK model shows best performance for TGA experiment and final volatile yield. • Bio-CPD model performs best in predicting volatile release rates in the FBR. • All models overpredict the tar yields compared to the experimental results. • Catalytic effects of ash and/or the hot bed surface are potential reasons. [ABSTRACT FROM AUTHOR]

• Heavy components in the condensed volatiles from amino acids pyrolysis were characterized. • Stable free radical intensity in char shows positive correlation with tar yields and heavy components average mass. • Heavy components from alanine were developed based polypeptide formation followed by dissociation of small groups. • Phenylalanine and tryptophan prefer to crack into radicals like C 8 H 7 N/C 12 H 10 N 2 ·and then recombine together. • Heavy components from the three amino acids all decreased above 550 °C, but the reasons are different. Heavy components, comprised of molecules with a substantial molecular mass, are essential constituents within volatiles. Within these molecules, nitrogen-containing compounds have a tendency to undergo transformation into coke during thermal treatment, exerting a substantial impact on the efficient and secure utilization of biomass. Three amino acids- alanine with an aliphatic structure, phenylalanine with additional aromatic features, and tryptophan with an extra heterocyclic ring were selected as model compounds, individually subjected to pyrolysis within the temperature range of 450 to 650 °C. The evolution of heavy components and the associated reaction mechanisms were comprehensively explored through extensive characterization and network analysis. The results showed that alanine transformed into heavy components mainly through dehydration followed by dissociation of CH 2 and CH. In contrast, phenylalanine and tryptophan tended to undergo fragmentation into C 8 H 7 N· and C 12 H 10 N 2 · derivatives, subsequently recombining to form heavy molecules. As the temperature increased, heavy components in alanine-derived volatiles monotonously decreased due to elimination reactions and the breaking of C–C bonds. Conversely, heavy components in phenylalanine and tryptophan initially increased and then decreased due to the enhanced cracked fragments, along with the competitive relationship between aromatization and polymerization reactions. For all three amino acids, there is a positive correlation among the average mass of heavy components, tar yield, and the intensity of permanent free radicals in the char. This implies that we may rapidly predict the evolutionary patterns of heavy components and tar through free radical detection. HCN dissociation is mathematically identified as a pivotal reaction in heavy component evolution, irrespective of amino acid type, possibly unveiling an important pathway for NOx formation. This study shows substantial theoretical significance for the eco-friendly and efficient conversion of nitrogen-rich biomass. [ABSTRACT FROM AUTHOR]

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

[Display omitted] • Effects of 13 potassium agents on products and elements distribution was studied. • Biochar, H 2 and CO 2 yields and phenols selectivity increase with agent basicity. • Biochar carbon sequestration relates to dehydrogenation that is crosslinking reaction. • Dehydrogenation relates to proton affinity and anion charge number. • Anion-dependent effects include shielding, competition, and parallel effect. Metal additives could significantly improve the product quality of biomass pyrolysis. However, the effect of anions added with metal cations has not been fully understood. To shed light on the anion effect, biomass pyrolysis assisted with different potassium agents was launched at parallel conditions, and the product and element distributions were investigated. Compared to the weak influence of neutral agents (i.e., KCl), alkali agents (i.e., KOH) strongly promote the formation of char (20.0–31.3 wt%), H 2 (15–92 cm3/g), and phenols (50–65 area %), but inhibit CO, carbohydrates, and furans. Oxidizing agents (i.e., KMnO 4) perform similar effects with alkali agents and raise the yields of CO 2 and H 2 O. Alkali agents facilitate carbon and hydrogen migration into biochar and gas, respectively, where higher basicity is related to enhancing the above tendency. Furthermore, proton affinities were calculated, and the correlation between dehydrogenation and additive properties including proton affinity and anion charge was first established. Based on the correlation results, the shielding effects of anions were disclosed, where the dehydrogenation effects of K+ were shielded by anions endowing low proton affinity. The competition effect of borate and phosphates anions hinders the K+ effect by introducing intermediate cross-linking structures. Besides, the self-decomposition of acetate, dehydrogenation catalyzed by iron and manganese, and dehydration catalyzed by chloride were recognized as parallel effects that do not severely influence the potassium effect. This study provides novel insight into the effect of additives in pyrolysis and will help reinvent the in-situ product-upgrading approach of biomass pyrolysis. [ABSTRACT FROM AUTHOR]

The effect of Brown's gas on the gas-phase tar cracking behavior, carbonic oxide (CO) production rate, and gaseous product temperature during the pine wood pyrolysis was preliminarily explored. By the application of cold trapping and gravimetric methods, it was found that Brown's gas reduces the energy barrier of thermochemical conversion for gas-phase tar, widens the temperature range of gas-phase tar accelerated cracking, and increases the cracking rate. When the pyrolysis temperature increases by 1 °C, the average cracking rate of gas-phase tar increases from C = 4.58 g⋅Nm−3 (flow volume ratio of Brown's gas to nitrogen, X(Brown's gas):N2 = 0%) to C = 4.8 g⋅Nm−3 (X:N2 = 1%) and C = 5.02 g⋅Nm−3 (X:N2 = 5%). While participating in the deep cracking of gas-phase tar, Brown's gas reduces the conversion energy barrier of the gas-phase tar to CO. The CO production rate rises from the initial 1.87% (X:N2 = 0%) to 4.22% (X:N2 = 1%) and 5.52% (X:N2 = 5%) per 1 °C of increased pyrolysis temperature. The consumption of Brown's gas is 0.32 m3 per 1 g⋅Nm−3 of gas-phase tar cracking within the pyrolysis residence time of 30 min. [ABSTRACT FROM AUTHOR]

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). [ABSTRACT FROM AUTHOR]

A hybrid residual modeling approach was proposed by combining the residuals of the pyrolysis equilibrium model and the Random Forest model, and results indicated that the hybrid residual model provided a more accurate prediction of the biomass pyrolysis process compared with the separate models. [Display omitted] • A hybrid residual modelling approach predicts the yield and heating value of biochar. • First principles coupled with physical laws to establish a pyrolysis equilibrium model. • Equilibrium model residuals as an input feature improves the accuracy of ML model. Predicting biochar yield and heating value poses a great challenge due to the complexity of the biomass pyrolysis process. Here, we propose a hybrid residual (HR) modelling approach by combining the residual of the pyrolysis equilibrium model and the Random Forest (RF) model. Then, the separate pyrolysis equilibrium model and the RF model were also established for comparison. These three models were evaluated in terms of R2 and RMSE, and results revealed that the HR model exhibited the optimal performance with R2 values of 0.890 and 0.956 for yield and higher heating value (HHV) of biochar, respectively. Permutation importance analysis and SHAP value analysis were conducted to rank the feature importance of the HR model. The results indicated that the ash, pyrolysis temperature, and residual are important for biochar yield; the ash, carbon, and residual are crucial for the HHV of biochar in the biomass pyrolysis process. Furthermore, simplified interpretable equations were developed based on the identified features. In conclusion, this work demonstrated through simple case studies that combining a mechanism model with a machine learning model can accurately establish complex process modelling and offer simplified equations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Porous modified biochar was prepared by ZIF-8-assisted pyrolysis of bamboo. • The surface area enhanced from 49.6 to 557.4 m2/g after ZIF-8-assisted pyrolysis. • The SO 2 adsorption capacity of modified biochar can reach 166 mg/g at 30 °C. • Polar ZnO on the carbon surface promotes the conversion of SO 2 to SO 3 2−. Structural modification is a necessary means to improve the adsorption performance of biochar. A simple, efficient, and well-applicable modification method is often expected. In this study, zeolitic imidazolate framework (ZIF-8)-assisted pyrolysis of bamboo was employed to prepare modified biochar for improving its SO 2 adsorption performance. The physicochemical characteristics of biochars before and after modification were investigated and their SO 2 adsorption behaviors were examined using a fixed bed adsorption system. The results showed that the surface heteroatoms and pore structure parameters of biochar modified by ZIF-8-assisted pyrolysis were significantly improved, with nitrogen content and surface area increasing from 1.3 wt% and 49.6 m2/g to 4.2 wt% and 557.4 m2/g, respectively. Among all tested conditions, the modified biochar obtained through ZIF-8-assisted pyrolysis at 700 °C exhibited not only the highest SO 2 adsorption capacity (166 mg/g) but also a remarkable increase (up to 121 %) compared with pristine biochar under identical pyrolysis temperature conditions. Moreover, it exhibited good regeneration performance, with an adsorption efficiency of over 93 % after 8 cycles of SO 2 adsorption and desorption. Combined with characterization results regarding physical and chemical properties before and after SO 2 adsorption, it can be concluded that improved pore structure and the presence of polar ZnO on the surface are primarily responsible for promoting SO 2 adsorption onto modified biochar, resulting in the final existence as SO 3 2− rather that SO 4 2−. [ABSTRACT FROM AUTHOR]

• Carbon-negative production of hydrogen-rich syngas from biomass were proposed. • The oxygen carriers NiFe 2 O 4 @SBA-16 was designed based on embedding strategy. • The reactivity and cycle stability was upgraded by embedding NiFe 2 O 4 in SBA-16. • The quality of syngas was improved by adding part of CO 2 into the feed gas. To realize the clean and efficient directional conversion of biomass, chemical looping reforming of biomass volatile CH 4 based on a decoupling strategy is expected to carry out carbon-negative production of hydrogen-rich syngas. In this paper, a multi-functional oxygen carrier (NiFe 2 O 4 @SBA-16) for encapsulating the active metal oxide component NiFe 2 O 4 with a three-dimensional interconnecting pore molecular sieve SBA-16 was designed. The experimental results showed that the modification strategy of composite metal oxide encapsulation improved syngas selectivity and CH 4 conversion based on the fixed-bed reactor. 20 %NiFe 2 O 4 @SBA-16 showed 22.1 % CH 4 conversion and 92.6 % CO selectivity under 750 °C, and it maintained good cycle stability after 15 cycles. The H 2 /CO ratio was effectively improved by adding part of CO 2 into the feed gas, and the CH 4 conversion reached over 35 %. This study provides essential data for the clean preparation of hydrogen-rich syngas from biomass and the development and design of multifunctional oxygen carriers. [ABSTRACT FROM AUTHOR]

This study presents the thermo-kinetics and thermodynamic analyses of date palm surface fibers (DPSFs) using thermogravimetric analysis. DPSFs were heated non-isothermally from 20 to 800 OC at a ramp rate of 10 OC/min in nitrogen atmosphere. Thermogravimetric analysis indicated that there have been two stages for pyrolysis of DPSFs. Kinetic and thermodynamic parameters have been calculated for the second stage which is further subdivided into two mass-loss regions. The low-temperature stable components were decomposed in a temperature range of 270–390 OC and high-temperature stable components were degraded in a temperature range of 390–600 OC. The Coats–Redfern integral method was employed with 21 different kinetic models from four major solid-state reaction mechanisms. Among all models, the two diffusion models: Ginstling–Brounshtein and Ginstling diffusion were the best fitted models with highest regression coefficient values (R2 > 0.99) in both mass-loss regions. For mass-loss regions: I (270–390 OC) and II (390–600 OC), the activation energy values were found to be 96–98 and 113–114 kJ/mol, respectively. Thermodynamic parameters (ΔH, ΔG, ΔS) were calculated using kinetic data. The findings reported herein are helpful in characterizing date palm fibers as a source of energy, designing reactors, producing chemicals, and understanding the properties of surface fibers for making composites. [Display omitted] • Kinetic and thermodynamic analysis of date palm surface fibers using Coats Redfern method. • Kinetic mechanisms from chemical reactions and diffusion, geometric, and nucleation models. • Two-stage mechanism has been observed in pyrolysis of date palm surface fibers. • Coats-Redfern method showed that palm fibers pyrolysis follows diffusion mechanism. • Ginstling–Brounshtein equation and Ginstling equation (4-D diffusion) are best fitted models. [ABSTRACT FROM AUTHOR]

Volatile state mathematical models for quantifying the chemical components in volatile biomass pyrolysis products were developed. The component mass yield Yi rate depends linearly on its pseudo kinetic constant and the remaining mass yield. The mass fraction rate of each component was modeled from the derivation of its mass yield rate equation. A new mathematical model equation was successfully developed. The involved variables are: biomass number, temperature, heating rate, pre-exponential factor, and pseudo activation energy related to each component. The component mass fraction yi and the mass yield were predicted using this model within a temperature range. Available experimental pyrolysis data for beechwood and rice husk biomass were used to confirm the developed model. The volatile products were separated into biopyrolysis gas (BPG) and a bio-pyrolysis oil (BPO). Five components in the BPG and forty in the BPO were quantified. The pseudo activation energy for each pseudo chemical reaction for a specific component was modeled as a polynomial function of temperature. The component mass fraction and yield are quantifiable using this developed mathematical model equation within a temperature range. The predicted component mass fractions and yields agreed excellently with the available experimental data. [ABSTRACT FROM AUTHOR]

Pyrolysis of triglycerides based on biomass was used at a large scale for fuel supply during the world wars. For this study, the bio-oil produced from waste fish oil pyrolysis was fractioned in a distillation column to produce a light fraction cut in the range of gasoline. This biofuel was tested in a motorcycle engine to measure its performance in terms of torque and to analyse its exhaust gas composition. The emissions were assessed by exploring the combustion of a fossil gasoline without additives and with blends of bio-gasoline, BG20 and BG30 fuels, meaning 20 and 30% of bio-gasoline in fossil gasoline, respectively. Results allowed for the identification of the torque and emission gases combinations for each fuel type and the determination that as the percentage of bio-gasoline in the gasoline was increased, the concentration of CO2, CH4, C2H6, C3H8 decreased in direct relation to the engine rotation. The results show that bio-gasoline can be used as an additive of fossil gasoline with gains of performance in terms of torque and lower concentration of CO2 in the emissions. The torque increased from 3.5 to 3.7 N m and from 4.0 to 5.0 N m in fifth gear and at 2000 and 4000 rpm, respectively. [ABSTRACT FROM AUTHOR]

Walnut shell pyrolysis liquefaction experiments for phenolic enrichment were conducted using torrefaction pretreatment and fractional condensation simultaneously. Bio-oil composition was comprehensively analyzed for elements, functional groups and componential contents. After high-temperature torrefaction, the proportion of lignin pyrolytic products in pyrolysis organic vapors showed significant increment. Fractional condensation further separated water, acetic acid and other small molecular compounds, and improved the phenolic content in the target bio-oil. Compared with the traditional pyrolysis liquefaction technology, when 363 K water bath was utilized to recover 300 °C torrefied walnut shell pyrolysis vapors, the C/O ratio in bio-oil increased from 0.5 to 1.6, and the proportions of H in aromatic ring and phenolic OH increased by 150% and 400%, respectively. The total content of detectable phenols was enriched from 2.7 wt% to 13.3 wt%. The optimized scheme on improving economic efficiency was provided for offsetting torrefaction energy consumption and low bio-oil yield. • Torrefaction pretreatment and fractional condensation were used to prepare bio-oil. • Variation in bio-oil composition under different preparation conditions was analyzed. • Phenolic enrichment mechanism by torrefaction and condensation was clarified. • Optimal temperatures of torrefaction and condensation were given to maximize phenols. • A revised scheme was provided for offsetting the disadvantages of torrefaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Machine learning was used to model T α in pyrolysis from preliminary analyses of biomass. • NN and RF algorithms were explored, and crucial hyperparameters were optimized. • With R2 of 0.9462 and RMES of 14.63 K, RF model presented high prediction accuracy. • α was the dominant factor on T α and the compositional properties contributed 1/3. • The results helped in reducing repetitive experiments and controlling the process. Biomass pyrolysis presents a viable solution to address the increasing global energy demand, and substantial efforts have been devoted worldwide to monitoring the conversion process through thermogravimetric experiments. In this study, the machine learning (ML) algorithm was employed to simulate and predict the temperature corresponding to specific conversion degrees (T α) by utilizing the compositional properties of the feedstock and heating rate as input variables. A dataset consisting of 1750 entries was collected from literature and deployed to construct neural network (NN) and random forest (RF) algorithms. After hyperparameter optimization, the RF model, equipped with 13 estimators and a maximum tree depth of 4, exhibited impressive accuracy in predicting T α , yielding an R2 value of 0.9462 and an RMES of 14.63 K. The subsequent feature importance analysis revealed that the conversion degree was the predominant influencing factor for T α , while the compositional properties of biomass accounted for 32.3 % of the overall influence. Validation experiments conducted using unexploited biomass further confirmed the robustness of the developed model. This research successfully demonstrated the feasibility of an ML approach in predicting reaction temperature based on preliminary feedstock analysis and desired pyrolysis progress, effectively eliminating the necessity for repetitive experiments. Furthermore, it provided valuable references for future ML research and applications in related fields. [ABSTRACT FROM AUTHOR]

[Display omitted] • Coke formation characteristics of biochar-based catalysts were systematically investigated. • Development of a MMCGM for characterizing coke on biochar-based catalysts at low temperatures. • Based on the mechanism and experimental data, the carbon particle stacking model was established. Coke formation is one of the major obstacles in the development of catalytic pyrolysis of biomass. The experiments were carried out on poplar wood chips using the biochar-based catalysts (poplar biochar: ZSM-5 = 1:2) to study the coke formation characteristics of biochar-based catalysts and to develop the kinetic models of coke formation. It is shown that the high temperature and long reaction time promoted the conversion of carbon from amorphous coke to graphitized coke. The higher the degree of graphitization of the coke, the higher the combustion temperature and the richer the cyclized structure. Activated coke and neutral coke were gradually converted to inert coke per unit mass of catalyst. Based on the experimental data, combined AIC evaluation system, it is found that the MMCGM (monolayer-multilayer coke growth model) can only describe the coke formation at low temperature well. Therefore, the kinetic model of carbon particle stacking model was established. This model can well describe the coke formation process on biochar-based catalysts. This study is expected to provide a guide for understanding the characteristics of catalyst coke formation and optimizing pyrolysis conditions and reactors. [ABSTRACT FROM AUTHOR]

Organic aerosol (OA) particles, as important parts of biomass pyrolysis tar, have a negative effect on the quality of pyrolysis oil by coking, while their physical and chemical properties are rarely reported. In this work, the flash and fast pyrolysis of lignocellulosic biomass and its individual components (cellulose, xylan and lignin) were conducted in a microfluidized-bed reactor (MFBR) and a U-shaped fixed-bed reactor (U-FBR), respectively. A vacuum ultraviolet photoionization aerosol mass spectrometer (VUV-PI-AMS) was used for the online characterization of chemical components of OA particles, and their size distributions were determined by a scanning mobility particle size spectrometer (SMPS). The effect of feedstock types, pyrolysis temperatures and heating rates on the properties of OA particles from biomass pyrolysis was investigated and discussed. The experimental results show that the chemical components of OA particles from biomass pyrolysis dominated by carboxylic acids, furans, pyrans, lignin monomers and oligomers. The sizes of biomass-derived OA particles center at about 110 and 240 nm for the flash and fast pyrolysis, respectively. All detected OA particles exist in the form of liquid state. The high heating rate would improve the formation of lignin oligomers in particle phase. • The properties of organic aerosol (OA) from biomass pyrolysis were studied. • MFBR was used to obtain the OA from flash pyrolysis of biomass. • The chemical characterization of OA was conducted by online VUV-PI-AMS. • The effect of pyrolysis conditions on the formation of OA was discussed. [ABSTRACT FROM AUTHOR]

Interaction between AAEMs and added metals in biomass has been reflected in the form of "auxiliary agents", ignoring the influence of self-contained AAEMs and the migration and transformation of biomass on the added transition metals. The fast/slow pyrolysis experiments of biomass containing Ni and K were conducted in the fixed bed reactor, and the interaction mechanism between self-contained K and added Ni was simulated using DFT. The results show that Ni is mainly distributed on the surface of the solid carbon matrix through adsorption and aggregated into nickel crystal particles. K accumulates inside the carbon matrix as C–K or C–O–K. K enhances the catalytic activity of Ni by enhancing the binding ability of Ni and biochar (increased to 354.89 kJ/mol), electron inversion and deficient oxygen. This study provides new insights into the design of biomass catalysts and the utilization of biomass energy. [Display omitted] [ABSTRACT FROM AUTHOR]

Biomass to biochar through pyrolysis is promising for carbon-negative biomass energy. Potassium could enhance biochar formation whereas the difference among potassium agents has not been understood. Herein, 13 potassium agents were adopted, and the product compositions and carbon distributions of slow and intermediate pyrolysis were investigated. Results show that neutral agents have a weak influence on the products, while high-basicity agents enhance biochar formation, decrease organics yields, and promote H 2 generation (9–144 cm3/g) and phenols selectivity (64–79 area%). Especially, due to the anion properties, borate and phosphates deviate from the basicity tendency; acetate contributes to increasing acetic acid selectivity (up to 43 area%) while oxidizing agents promote CO 2 and H 2 O yields. Potassium performs obvious enhancement of biochar carbon sequestration, increasing by 2–49 % for intermediate pyrolysis and -8–51 % for slow pyrolysis with biochar carbon retention reaching 55 % and 77 %, respectively. Meanwhile, the thermally unstable phases of biochar were also generated. General correlation analysis indicates that CO yields and phenols selectivity highly relate to biochar carbon retention. This study sheds light on the key role of acid-base properties and anion properties, and provides insight into AAEM-catalytic biomass pyrolysis. [Display omitted] • Acid-base properties of additives have essential influence on pyrolysis products. • Anion properties such as cross-linking cause differences in specific products. • Slow pyrolysis benefits biochar carbon sequestration and phenols selectivity. • Promotion of cross-linking by potassium lowers biochar thermal stability. • Key roles of potassium in cross-linking and polycondensation are revealed. [ABSTRACT FROM AUTHOR]

Laser-based Raman spectroscopy is a powerful technique for non-intrusive measurements of chemical composition in gas, liquid, and solids. However, weak signals make it challenging to employ the technique for diagnostics under harsh conditions with various background interferences. To overcome such limitations, we have devised a method, polarization lock-in filtering (PLF) based on temporal modulation of the excitation laser polarization, to filter out polarization-independent signals from acquired data. The PLF method applied for continuous Raman spectroscopy measurements of a biomass pyrolysis process showed promising filtering abilities for unwanted background fluorescence signals. A broadband fluorescence background interference was suppressed by up to a factor of 50. Therefore, released species during the biomass pyrolysis process were readily identified with their Raman spectrum signatures and their amounts quantified. In addition, the PLF method provided Raman spectra of low background, from which a gradual change in hydrocarbons released at different stages during the pyrolysis could be observed. Altogether, the efficient background suppression method increases the general applicability of Raman spectroscopy under conditions where interfering signals present a challenge and a limiting factor. [ABSTRACT FROM AUTHOR]

The influences of hydrochloric acid washing on the pyrolysis behavior and thermodynamic parameters of sweet sorghum stalk were investigated using thermogravimetric analysis and Fourier transform infrared (FTIR) in this study. Hydrochloric acid washing influenced the quality of sweet sorghum stalk and changed the pyrolysis curves shape. By acid pretreatment, the 98% of metals and 47.15% of extractives were removed, the maximum weight loss rates were improved by 1.53–1.64 times, the volatiles yields were enhanced about 10%, and the high heat value increased from 15.59 to 18.27 MJ/kg. Lower activation energies were obtained for acid-washed samples at conversion rate >0.45 by the Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose (KAS) methods. The higher Gibbs free energy of 133.94–137.79 kJ/mol could provide more energy for pretreatment samples, and FTIR analysis confirmed acid washing could change functional groups in samples. • Hydrochloric acid washing greatly removed the metals of sweet sorghum stalk. • The DTG curves of sweet sorghum stalk appeared four obvious mass-loss peaks. • Pretreatment significantly affected the shapes of pyrolysis curves. • Hydrochloric acid washing increased volatiles yield and HHV and Gibbs free energy. • Pretreatment reduced activation energy as conversion degree was more than 0.45. [ABSTRACT FROM AUTHOR]