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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]

In this study, the Density Functional Theory (DFT) Calculations for Molecules and Clusters—ADF module is employed to model carbon-supported nickel catalysts and lignin monomers, integrating the ReaxFF module to simulate molecular dynamics under supercritical water conditions, with a focus on lignin decomposition reactions. Molecular dynamics models for supercritical water gasification are established under various conditions such as catalyst presence, water molecule quantities, and reaction temperature. By comparing simulation systems under different conditions, the yields of and variations in combustible gases (hydrogen and carbon monoxide) are summarized. Introducing heteroatoms into the lattice of the carbon support can alter the electronic structure within graphene, thereby influencing its electrical and electrochemical properties, increasing the number of active sites, and significantly enhancing electrocatalytic activity. Simulation results indicate that carbon-supported nickel metal catalysts can promote the cleavage of C–C bonds in lignin monomers, thereby increasing the rate of water–gas shift reactions and boosting hydrogen production in the system by 105%. Increasing water molecule quantities favored water–gas shift reactions and hydrogen generation while lowering carbon monoxide formation. Moreover, elevating reaction temperatures led to increased hydrogen and carbon monoxide production rates, which were particularly pronounced between 2500 K and 3500 K. These findings offer crucial theoretical insights for advancing efficient hydrogen production through biomass supercritical water gasification. [ABSTRACT FROM AUTHOR]

Native polyculture microalgae have significant potential as feedstocks for biofuels, but a thorough understanding of their pyrolysis kinetic parameters is required to convert them to biofuels efficiently. This study used thermogravimetric analysis (TGA) to examine the pyrolysis properties and kinetics of native polyculture microalgae. The biomass was pyrolysed from room temperature to 800 °C at four heating rates: 10, 20, 30, and 40 °C min−1. The thermal decomposition was analysed using two model-free methods: Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO). It was found that thermal decomposition occurred in three stages: the dehydration stage, the active pyrolysis stage, and the passive pyrolysis stage. The maximum decomposition occurred between 186.7 to 531.7 °C, indicating the simultaneous decomposition of carbohydrates and proteins. The higher heating rates increased the total volatile matter and moved the peak pyrolysis temperature to a higher value due to limited heat transfer. The average activation energy determined by the KAS method (144.11 kJ mol−1) and the FWO method (147.43 kJ mol−1) were in agreement with each other, indicating that the obtained results are reliable. Also, a high R2 of 0.96 – 0.99 indicates that the points fit well. These findings provide useful information for designing pyrolytic systems using polyculture microalgal feedstock and suggest that polyculture microalgae could be a cost-effective alternative for biofuel 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.

The increasing demand for sustainable agricultural practices aimed at reducing carbon dioxide emissions has driven the exploration of converting viticulture residues into biochar. This study investigates the potential technological applications of biochar as a filler for the production of electrically conductive composite materials, suitable to Bipolar Plate (BP) manufacturing. Grape seeds (GSs), defatted grape seeds (DGSs), wood stems (WSs), and whole grape seeds (WGSs) were converted into biochar samples through low-temperature (300 °C) pyrolysis for 3 or 24 h. The composition and thermal stability of biochar were evaluated through thermogravimetric analysis (TG), which provided valuable insights into interpreting the in-plane conductivity (IPC) values of the BP samples. Pyrolyzed GS and DGS biochar samples demonstrated enhanced thermal stability and conferred higher IPC values compared to WS counterparts. This indicates a clear correlation between the formation of carbon-rich structures during pyrolysis and overall electrical conductivity. In contrast, pyrolyzed WGSs produced BP samples with lower IPC values due to the presence of lipids, which were not effectively degraded by the low-temperature pyrolysis. [ABSTRACT FROM AUTHOR]

This study investigated the combustion characteristics of mixed straw char and coal powder when used in blast furnace injection. The experiments examined the effects of mixing ratios between biomass char types of wheat straw char, corn straw char as well as cotton straw char, and anthracite coal on combustion characteristics and the injection effect of blast furnace. The results show that a 1:1 mixing ratio of wheat straw char and anthracite coal yields the best combustion characteristics, followed by a 1:1 ratio of corn straw char and anthracite coal. A 2:1 mixture of cotton straw char and anthracite coal exhibits the highest combustion efficiency. The study on the grindability of the mixtures indicates that straw char is easier to grind due to its brittleness. Blast furnace coal injection experiments reveal that a 50:50 mixture of cotton straw char and anthracite coal achieves the highest combustion efficiency at 74%, which is a 20.2% improvement compared to mixtures of bituminous coal and anthracite coal, significantly outperforming the other ratios. The findings underscore the importance of integrating renewable biomass resources in industrial applications to enhance sustainability in the metallurgical industry. [ABSTRACT FROM AUTHOR]

During the last century, benzene (C6H6) has been a highly studied substance, with some acute and chronic exposures leading directly to hematologic effects detected in humans. This work reports on preparing and examining biomass-derived activated carbons (HPACs) featuring high benzene adsorptive capacity. The fundamental goal of this paper is to propose a green approach for generating HPACs from Heracleum platytaenium Boiss. (Cow parsnip) as woody biomass using a low-cost approach. The characterization showed that chemical activation elicits more enhanced mesoporous structure, a higher degree of graphitization, and bulk porous structure with higher specific surface area and pore volume. To minimize the use of chemicals in the manufacture of high-performance HPACs, an essential pre-pyrolysis step was implemented prior to the chemical activation of biomass by NaOH. The samples were carbonized at different temperatures (500–900 °C) and named as HPAC500, HPAC600, HPAC700, HPAC800, and HPAC900. Considering micropore volume and total surface area, HPAC600 was superior, and maximum benzene adsorption capacities were: HPAC600 (127 mg/g) > HPAC700 (117 mg/g) > HPAC800 (101 mg/g) > HPAC500 (80 mg/g) > HPAC900 (59 mg/g) at selected conditions. Freundlich, Langmuir, and pseudo-first-order (PFO) and pseudo-second-order (PSO) models were used to mathematically describe HPAC600-vapor benzene sorption on HPAC600. The kinetic findings fitted PFO with optimal values of R2 = 0.999, and the isotherm model adsorption fitted Freundlich model (R2 = 1.000). The finding revealed that H. platytaenium is a useful material for producing adsorbents, and successful testing outcomes demonstrate that H. platytaenium products serve as a suitable benzene absorbent. [ABSTRACT FROM AUTHOR]

To investigate the control mechanisms of NOx precursors and the synergistic effects of composite catalysts during proline pyrolysis, a systematic series of experiments was conducted utilizing composite catalysts with varying Fe-Ca ratios. Product distribution analysis was employed to elucidate the catalysts' mechanisms in reducing NOx precursor emissions. The synergistic interactions between Fe and Ca were quantitatively assessed through comparative theoretical and experimental release calculations. The results indicate that an increase in the Fe content in the catalyst led to a rise in amine concentrations from 0.9% to 2.95%, implying that Fe facilitates the generation of amine-N through ring-opening and substitution reactions. When the Fe to Ca ratio was balanced at 1:1, nitrogen predominantly participated in the formation of purines via cyclization and substitution reactions. Additionally, all composite catalysts exhibited a suppressive effect on the release of NOx precursors, attributed to their significant enhancement of solid product retention. Fe-Ca composite catalyst synergistically inhibits the release of gaseous nitrogen. Notably, the strongest synergistic effect was observed with a 1:3 Fe to Ca ratio, which reduced the release of NH3 by 38.7% and HCN by 53.6% during proline pyrolysis. This study offers valuable insights into the control of NOx precursors and the optimization of nitrogen-rich biomass pyrolysis processes. [ABSTRACT FROM AUTHOR]

Study on the soot behaviors in hemicellulose pyrolysis is essential for the enhancement of gasification performance and solution of PM-related problems. In this work, a one-dimensional model is adopted to calculate the heating up and pyrolysis of xylan. The primary devolatilization is calculated by bio-CPD model, while the soot formation is simulated with one-step reaction with tar as the precursor. The effect of particle distance, soot radiation, and thermophoresis force on soot behaviors are discussed in detail. A smaller particle distance leads to less soot during xylan pyrolysis, which is contrary to the trend in biomass gasification. For pyrolysis, soot formation rate dominates, which decreases when particle distance decreases. For gasification, soot consumption rate dominates, which decreases when particle distance decreases. Soot radiation during xylan pyrolysis tends to heat up the soot itself and tar since their temperature is lower than ambient temperature, which is different from combustion and gasification conditions. Thus, when soot radiation is included in the model, temperature is higher and all soot-relevant reactions are faster. At the late stage of xylan pyrolysis, diffusion makes soot move towards both xylan particle and outer boundary, while thermophoresis offers an additional driven force for soot to get close to xylan particle. When thermophoresis is included in the model, soot mass fraction decreases more slowly at the late stage. [ABSTRACT FROM AUTHOR]

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Among the approaches to facilitating negative CO2 emissions is biochar production. Biochar is generated in the pyrolysis of certain biomasses. In the pyrolysis process, carbon in the biomass is turned into a solid, porous, carbon-rich, and stable material that can be captured from the soil after a period of from a few decades to several centuries. In addition to this long-term carbon sequestration role, biochar is also beneficial for soil performance as it helps to restore soil fertility and improves the retention and diffusion of water and nutrients. This work presents a Life Cycle Assessment of different pyrolysis approaches for biochar production. Biomass pyrolysis is performed in a fixed-bed reactor, which operates at a mild temperature (550 °C). Biochar is obtained as solid product of the pyrolysis, but there are also liquid (bio-oil) and gaseous products (syngas). The pyrolysis gas is partly used to fulfil the energy demand of the pyrolysis process, which is highly endothermic. In the conventional approach, CO2 is produced during the combustion of syngas and emitted to the atmosphere. Another approach to facilitate CO2 capture and thus obtain more negative CO2 emissions in the pyrolysis process is burning syngas and bio-oil in a Chemical Looping Combustion unit. Life Cycle Assessment was performed of these approaches toward biomass pyrolysis to evaluate their environmental impact. The Chemical Looping Combustion approach significantly reduced the values of 7 of the 16 environmental impact indicators studied, along with the Global Warming Potential among them, it slightly increased the value of one indicator related to the use of fossil resources, and it maintained the values of the remaining 8 indicators. Environmental impact reduction occurs due to the avoidance of CO2 and NOx emissions with Chemical Looping Combustion. The CO2 balances of the different pyrolysis approaches with Chemical Looping Combustion configurations were compared with a base case, which constituted the direct combustion of wheat straw to obtain thermal energy. Direct biomass combustion for the production of 17.1 MJ of thermal energy had CO2 positive emissions of 0.165 kg. If the gaseous fraction was burned by Chemical Looping Combustion, CO2 was captured and the emissions became increasingly negative, until a value of −3.30 kg/17.1 MJ was generated. If bio-oil was also burned by this technology, the negative trend of CO2 emissions continued, until they reached a value of −3.66 kg. [ABSTRACT FROM AUTHOR]

The production of hydrogen from plastic and biomass waste via processes powered by renewable electricity can be a pivotal contributor to an effective waste management system in a circular economy. Copyrolysis of plastic and biomass waste mixtures can be economically appealing, not only by eliminating the need for waste stream separation but also by potentially synergizing hydrogen production. In this study, we present evidence of such hydrogen production synergy in plasma copyrolysis of mixtures of low-density polyethylene (LDPE) and cellulose (CE) as plastic and biomass waste models, respectively. We treated samples made of mixtures of LDPE and CE powders at five different mass ratios, ranging from 100% LDPE to 100% CE. We used non-thermal nitrogen plasma and argon plasma in a Streamer Dielectric-Barrier Discharge (SDBD) configuration under atmospheric pressure conditions. Synergistic hydrogen production was observed when nitrogen was used as the working gas, but not with argon, resulting in up to 37% greater hydrogen production compared to non-synergistic expectations. This outcome is attributed to the nitrogen-doped oxygenated carbonaceous residues from CE pyrolysis catalyzing the dehydrogenation and reforming of light alkanes resulting from the decomposition of LDPE. [Display omitted] • Plasma copyrolysis of LDPE and cellulose using nitrogen leads to increased hydrogen yield. • Synergy leads to up to 37% increased hydrogen production. • The lowest energy cost of 1.5 MWh/kg-H 2 is achieved for 1:2 LDPE:cellulose mass ratio. • Synergy attributed to nitrogen doping of cellulose-derived carbonaceous residues. [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]

Abstract 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.

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]

Lignocellulosic biomass is seen as a promising environmentally benign replacement for carbon-based fuels as well as a feedstock for chemicals. The energy contained in biomass can be explored using variety of ways. Pyrolysis is the first step in both gasification and combustion and is the most fundamental process in the thermochemical conversion of biomass. The pyrolysis products, namely the liquid product (bio-oil and aqueous condensate) and the char, however, could not be used as a direct source of fuel due to their limitation of quality and thus require upgradation. Thus, further advancements in pyrolysis technology, such as pre-treatment of raw materials and/or post-treatment or downstream processing of raw pyrolysis products to generate upgraded fuel with attributes similar to those of fossil fuels, are critical for effective biomass utilization. The present work provides a broad overview of the detailed biomass type and their composition, exhaustive insights about the pyrolysis process as a biomass conversion technology as well as the pyrolysis products. The most important aspects of the manuscript is to highlight the research undertaken for the upgradation of the different pyrolysis products to obtain a high quality end products that could substitute the fossil fuel. [ABSTRACT FROM AUTHOR]

Biochar is a biomaterial obtained by pyrolysis with high porosity and high specific surface area (SSA), which is widely used in several fields. The yield of biochar has an important effect on production cost and utilization efficiency, while SSA plays a key role in adsorption, catalysis, and pollutant removal. The preparation of biochar materials with better SSA is currently one of the frontiers in this research field. However, traditional methods are time consuming and laborious, so this paper developed a machine learning model to predict and study the properties of biochar efficiently for engineering through cross-validation and hyper parameter tuning. This paper used 622 data samples to predict the yield and SSA of biochar and selected eXtreme Gradient Boosting (XGBoost) as the model due to its excellent performance in terms of performance (yield correlation coefficient R2 = 0.79 and SSA correlation coefficient R2 = 0.92) and analyzed it using Shapley Additive Explanation. Using the Pearson correlation coefficient matrix revealed the correlations between the input parameters and the biochar yield and SSA. Results showed the important features affecting biochar yield were temperature and biomass feedstock, while the important features affecting SSA were ash and retention time. The XGBoost model developed provides new application scenarios and ideas for predicting biochar yield and SSA in response to the characteristic input parameters of biochar. [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]

The article proposes a technological scheme of a heliopyrolysis plant with a parabolic solar energy concentrator and presents the results of a study of the thermal technological regime of the process of pyrolysis of sunflower waste. To study the process, an experimental heliopyrolysis installation with a parabolic solar concentrator was created. The purpose of this work is to evaluate the practical possibility of solar technology for the thermal processing of sunflower waste using a parabolic solar concentrator and to determine the main parameters of the thermal technological regime of heliopyrolysis. The results of experimental studies of the process of heliopyrolysis of sunflower waste at a temperature of 400–500°C are presented. The values of the heat of combustion of liquid and gaseous biofuels obtained by solar pyrolysis were determined. It has been established that the value of the lower calorific value of liquid pyrolysis fuel is 35–40 MJ/kg, and the calorific value of gaseous fuel is 25–28 MJ/m3. During the experiments, the temperature dependence and material balance of the resulting products during the thermal processing of sunflower waste using concentrated solar thermal energy were studied. In experiments carried out at the installation, as a result of the pyrolysis of 1 kg of sunflower waste loaded into the reactor of a heliopyrolysis installation, 63% of biochar, 10% of liquid, and 27% of gaseous biofuels were obtained. The results of the studies showed that the yield of liquid pyrolysis products is affected by the humidity of the initial biomass; and the maximum yield of the liquid pyrolysis, and product of sunflower waste corresponds to a temperature of about 430°C and a humidity of the loaded initial biomass of 25%. Based on the conducted research, the effectiveness and possibility of using a heliopyrolysis installation with a solar parabolic concentrator to maintain the required temperature regime for the pyrolysis of sunflower waste in the daytime operating mode of the installation was substantiated. [ABSTRACT FROM AUTHOR]

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.

In this study, the Density Functional Theory (DFT) Calculations for Molecules and Clusters—ADF module is employed to model carbon-supported nickel catalysts and lignin monomers, integrating the ReaxFF module to simulate molecular dynamics under supercritical water conditions, with a focus on lignin decomposition reactions. Molecular dynamics models for supercritical water gasification are established under various conditions such as catalyst presence, water molecule quantities, and reaction temperature. By comparing simulation systems under different conditions, the yields of and variations in combustible gases (hydrogen and carbon monoxide) are summarized. Introducing heteroatoms into the lattice of the carbon support can alter the electronic structure within graphene, thereby influencing its electrical and electrochemical properties, increasing the number of active sites, and significantly enhancing electrocatalytic activity. Simulation results indicate that carbon-supported nickel metal catalysts can promote the cleavage of C–C bonds in lignin monomers, thereby increasing the rate of water–gas shift reactions and boosting hydrogen production in the system by 105%. Increasing water molecule quantities favored water–gas shift reactions and hydrogen generation while lowering carbon monoxide formation. Moreover, elevating reaction temperatures led to increased hydrogen and carbon monoxide production rates, which were particularly pronounced between 2500 K and 3500 K. These findings offer crucial theoretical insights for advancing efficient hydrogen production through biomass supercritical water gasification.

Electrolysis of water can generate green hydrogen as a sustainable energy resource, which mitigates the impacts of climate change caused by burning fossil fuels and excessive carbon emissions. Cheap and abundant transition metal compounds are emerging as promising candidates to replace noble metal catalysts. Yet their poor conductivity is a critical challenge to obtain a high activity. In this study, we present a facile approach to construct the nanocomposite of NiSe 2 embedded on multi-element (N, S) doped carbon derived from biomass. The synthesized electrocatalyst (NiSe 2 @C) exhibited an active hydrogen evolution electrocatalyst with a low overpotential of 206 mV to obtain a current density of 10 mA cm−2 and a small Tafel slope of 59 mV dec−1. Electrochemical analysis ascribed the high catalytic performance to the synergistic effect of the NiSe 2 nanoparticles with large active sites and the superior conductive carbon framework, boosting the charge transfer for hydrogen generation. The findings may lead to new opportunities for enhancing hydrogen generation from electrochemical water splitting using earth-abundant catalysts. [Display omitted] • A facile and low-cost synthesis of nanocomposite for HER was introduced. • NiSe 2 nanoparticles embedded in biomass-derived carbon (NiSe 2 @C) was constructed. • NiSe 2 @C exhibits a low overpotential of 206 mV and a Tafel slope of 59 mV dec−1. • The catalytic activity enhancement is originated from the conductive support and high surface area of active sites. [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]

In response to the global climate challenge and the increasing demand for energy, exploring renewable energy alternatives has become crucial. Bio-oils derived from biomass pyrolysis are emerging as potential replacements for fossil fuel-based liquid fuels. This paper shares findings from the Institute of Energy and Fuel Processing Technology on the quality of crude biomass pyrolysis bio-oil samples. These findings highlight their potential as motor liquid fuels. The article details the results of tests on the physicochemical properties of four distinct bio-oil samples. Additionally, it presents preliminary test results on the hydrodeoxygenation of bio-oils in a batch reactor. The production of homogeneous, stable mixtures using other fuel additives, such as diesel oil, rapeseed methyl ester (RME), and butanol, is also discussed. [ABSTRACT FROM AUTHOR]

The straw-type biomass, as a green and alternative reductant for the suspension magnetization roasting (SMR) of iron ores, is proposed. The roasted products are investigated at a roasting temperature of 750 °C, the roasting time of 7.5 min and the biomass dose of 25%. The iron phase results indicate that hematite ores were reduced to magnetite by the biomass, and the magnetization transformation increased from 0.64 A·m2·g−1 to 36.93 A·m2·g−1. The iron ore microstructure evolutions of holes and fissures are detected by SEM-EDS. The biomass pyrolyzed to form CO2, CO, CH4, H2O, H2, C=O, benzene skeleton, C-Hand C-O compounds at 200–450 °C, while the mass loss of the magnetization roasting process occurred at 450–750 °C by using TG-FTIR. The GC/MS results showed that the organic gases preferred to produce the O-heterocycles at 329 °C while the hydrocarbons were dominant at the high temperature of 820 °C for the hematite ore and biomass mixture. The gas composition analysis explained that the reducing gaseous products (CO, CH4 and H2) were used as a reductant and consumed obviously by hematite ore in the SMR process. The innovative utilization of biomass waste was effective for iron recovery of hematite ore and contributes to the reduction of greenhouse gases and the protection of the environment. [ABSTRACT FROM AUTHOR]

To enhance the catalytic performance of nickel-based catalysts and improve their efficiency in biomass pyrolysis, a nickel-based catalyst supported on a ZnZr composite carrier was synthesized using the sol-gel method. The morphological changes of the catalyst before and after the reaction were observed using X-ray diffraction, scanning electron microscopy, nitrogen gas adsorption, temperature-programmed reduction, and other methods to analyze its catalytic performance. A series of experiments were conducted to explore the optimal conditions for the catalyst's gas production, including carrier material ratios, loading amounts, residence time, and reaction temperature. The bimetallic carrier of Zn and Zr provided a higher specific surface area, allowing the metallic nickel to enter its mesopores. The synergistic effect of the bimetallic system facilitated the catalytic activity of nickel, significantly enhancing gas production. The maximum CO and H2 production were achieved at Zn/Zr = 6/4. The catalyst achieved an optimal gas yield of 507 mL/g at a residence time of 20 min and a reaction temperature of 800 °C, demonstrating strong stability.

The increasing demand for sustainable agricultural practices aimed at reducing carbon dioxide emissions has driven the exploration of converting viticulture residues into biochar. This study investigates the potential technological applications of biochar as a filler for the production of electrically conductive composite materials, suitable to Bipolar Plate (BP) manufacturing. Grape seeds (GSs), defatted grape seeds (DGSs), wood stems (WSs), and whole grape seeds (WGSs) were converted into biochar samples through low-temperature (300 °C) pyrolysis for 3 or 24 h. The composition and thermal stability of biochar were evaluated through thermogravimetric analysis (TG), which provided valuable insights into interpreting the in-plane conductivity (IPC) values of the BP samples. Pyrolyzed GS and DGS biochar samples demonstrated enhanced thermal stability and conferred higher IPC values compared to WS counterparts. This indicates a clear correlation between the formation of carbon-rich structures during pyrolysis and overall electrical conductivity. In contrast, pyrolyzed WGSs produced BP samples with lower IPC values due to the presence of lipids, which were not effectively degraded by the low-temperature pyrolysis.

Activated biochars were obtained from pyrolysis and CO2-physical activation of four different biomasses including tannery shaving waste (T), vine wood waste (W), barley waste (B) and Sargassum, brown macroalgae of Venice lagoon (A). The potential of obtained carbonaceous materials as the supports of Ni,Al catalysts was investigated in levulinic acid (LA) conversion to γ-valerolactone (GVL) as a model hydrogenation reaction. Al-containing species as the Lewis acid sites for the dehydration step were incorporated to the supports using wet impregnation or precipitation. Ni as a hydrogenation active phase was added to the supports via wet impregnation. Biochar-based supports and catalysts were characterized by AAS, elemental analysis, FTIR, N2 physisorption, XRD, SEM, EDS, TEM, He-TPD, NH3-TPD and TPR techniques. The catalysts were tested for LA hydrogenation to GVL in a batch system and aqueous medium. The results showed that Ni supported on activated biochar was not active due to a lack of Lewis acid sites for dehydration. Precipitated Al-containing species on the biochar-based supports demonstrated a better catalytic performance in the reaction compared to impregnated one because of different interactions with the support and Ni species. Among different supports, the activated biochars obtained from T and W acted as the best ones. A higher catalytic efficiency was strongly influenced by the chemical (aromaticity and stability, presence of N,O-doped and functional groups), textural (the porous texture and surface area), and morphological (higher dispersion of active phases) properties of activated biochars obtained from different biomasses with different natures.

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]

The conversion of biomass-derived oxygenates over zeolite catalysts constitutes a challenge for the efficient production of bio-based chemicals and fuels due to difficulty in controlling the selectivity and high coke formation of such reactions. This is partly attributed to the microstructure of zeolite catalyst which affects the conversion and selectivity of products derived from biomass-derived oxygenates. In this study, the conversion and deactivation characteristics of three different model oxygenates found in biomass bio-oil (namely, acetol, furfural and guaiacol) over ZSM-5 zeolites of varying acidity, pore and crystal size prepared with bottom-up and top-down approaches were evaluated using a fixed bed microreactor at atmospheric pressure and a space velocity of 5 h−1 at a temperature range of 450–650 °C. Analysis of the experimental results indicates that the optimum temperature for such conversions is in the vicinity of 600 °C allowing for complete conversion of the compounds and high resistance to coking. The mechanisms of those conversions are discussed based on the obtained results. In general, crystal size and mesoporosity induce easier access to active sites improving mass transfer but also alter the location type, and strength of acid sites allowing for higher yields of primary and intermediate products such as olefins. [ABSTRACT FROM AUTHOR]

The work presents a technological diagram of a heliopyrolysis device with a parabolic concentrator for the thermal processing of biomass and organic waste to produce alternative fuel. An experimental heliopyrolysis device was created and its main characteristics were substantiated. The results of experimental studies of the temperature regime and material balance of pyrolysis of biomass and various organic wastes are presented, taking into account the intensity of solar radiation in the conditions of the city of Karshi. An analysis of the material balance of pyrolysis of biomass and organic waste using concentrated solar energy was carried out. It has been established that through the use of a parabolic solar concentrator as the main heater of the reactor, it is possible to create the required temperature regime for pyrolysis within the temperature range of 350–500°C. The cycle duration of the biomass pyrolysis process averages 180–240 min. The conducted studies show that during the daytime in sunny weather, three or four cycles can be carried out in the proposed unit. As a result, it becomes possible to compensate for the thermal energy that is consumed for the device's own needs with solar energy. It was concluded that with slow pyrolysis of biomass and organic waste, the intensity of the yield of gaseous fuel increases from 10 to 30% with an increase in temperature from 100–350°C; the yield of liquid pyrolysis products in the temperature range of 150–350°C increases from 5 to 22%. The analysis of the temperature regime and material balance of the heliopyrolysis device shows the feasibility of its use for the producing alternative fuel from biomass. [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]

Ni-based catalysts are used in a wide range of biomass catalytic reactions. To further improve the catalytic performance and anti-deactivation ability of the catalyst, a Ni/CaZnAl catalyst was synthesized by using the sol–gel method. N2 adsorption–desorption, X-ray fluorescence spectroscopy (XRF), temperature programmed reduction (TPR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to determine the activity of the catalyst. In addition, the impacts of various conditions on the catalytic performance were assessed in terms of gas composition and production and syngas generation (especially H2). The experimental results show that 15% Ni/CaZnAl catalyst calcined at 500 ℃ and pyrolyzed at 800 ℃ for 20 min has the best effect on producing hydrogen-rich syngas. Compared with the catalyst calcined at 400 ℃, calcined at 500 ℃ has stronger stability and metal-support interaction, but its carbon resistance is slightly weaker. Under the optimum experimental conditions, the syngas output of 15% Ni/CaZnAl is 424.8 ml/g, which is 2.30 times higher than that of non-nickel (184.8 ml/g). After six times of use, the syngas output remains at 247.6 ml/g, which is more elevated than that without Ni by 33.98vol%. [ABSTRACT FROM AUTHOR]

Biochar, a sustainable solid material derived from biomass pyrolysis enriched in carbon, has emerged as a promising solution for soil carbon sequestration. This comprehensive review analyzes the current knowledge on biochar's application in this context. It begins by examining biochar properties and production methods, highlighting its recalcitrant nature as a potential stable carbon sink. The influence of various feedstocks and pyrolysis conditions on various physicochemical properties of biochar and its soil carbon sequestration potential is explored. Mechanisms through which biochar enhances soil carbon sequestration are discussed, including its role as a physical barrier against carbon loss and its ability to promote stable soil aggregates and influence soil microorganisms. Challenges and limitations, such as variations in biochar properties and optimal application rates, are addressed, along with strategies for maximizing biochar effectiveness through amendments. The review concludes by emphasizing the importance of long-term field studies, standardized protocols, and economic assessments to support the widespread adoption of biochar for soil carbon sequestration and its potential in climate change mitigation. [ABSTRACT FROM AUTHOR]

A novel interconnected screw reactor was proposed to convert biomass to bio-oil and bio-char in this study. This reactor is expected to achieve direct heating of pyrolysis feedstocks and increase the reactor processing capacity through the recycling of biochar between the inner and outer screw. Here, we simulated the biomass particle flow and reaction process in this interconnected reactor by an extended discrete element method (DEM), the effect of char circulation on the reactor temperature distribution and the product yields are investigated. The results show that the char circulation increased the heating rate of biomass. At the inner and outer screw speed of 10 rpm and 1 rpm, the char circulation can reach 5.15 kg/h and the average temperature of biomass under the char circulation is about 30 °C higher than that without char circulation. The reaction simulation results show that at 500 °C, the yield of char, bio-oil and non-condensable gas are 18.9%, 40.6% and 40.5% respectively. The predicted product yields of char, bio-oil and non-condensable gas are also in good agreement with the experimental measurements. [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.

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.

Hydrogen release during pyrolysis of woody biomass is studied considering anisotropicity and inhomogeneity of wood structure. A new anisotropic shrinkage model is proposed based on the decomposition of main wood constituents, i.e., cellulose, hemicellulose, and lignin. The new shrinkage model can predict the temporal evolution of the wood structure, and the differences between axial and radial shrinkage during pyrolysis. The model agrees very well with several experimental data from the literature. Based on particle temperature during conversion, the pyrolysis is partitioned into four stages, and the hydrogen release and H 2 formation from each stage are investigated. Stage (IV) of pyrolysis, from 1000 to 1273 K, is found to be efficient for H 2 production owing to the production of considerable mass of H 2 with a minimal amount of tar species. Furthermore, the char quality is found to be different at the end of stages (II), (III), and (IV), where around 67.7, 80.5, and 93.4% wt. of solid residue is made of carbon, respectively. The model is also used to explain how the heating rate affects the temperature distribution inside the particle and how it shifts the peak of hydrogen release. Finally, the pyrolysis of two inhomogeneous wood samples — a beech twig with bark and a beech dowel with growth rings — are investigated. The bark can affect the pyrolysis rate, products, and flow pattern inside the particle. The growth rings do not have a considerable effect on the pyrolysis rate and products, but they have a significant impact on the flow pattern. This has an important implication for char conversion studies where the internal surface area and porosity field distribution have a significant effect on the gasification and oxidation rates. [ABSTRACT FROM AUTHOR]

The main objective of the current work is to study the performance of the NiO and Ce2O3 loaded HZSM-5 catalyst on the catalytic upgrading of oxygenated pyrolysis vapours from sugarcane bagasse into high-quality pyrolysis oil consisting of C6–C8 hydrocarbons. The experiments were performed at five different pyrolysis reaction temperatures (400, 450, 500, 550 and 600 °C) via in situ fixed bed reactor. The HZSM-5 was used as a support, while nickel oxides and/or cerium oxides were impregnated via incipient wetness impregnation method. The catalyst-to-biomass mass ratio was kept constant at 1:1 for all investigated samples. The results revealed that the NiO-Ce2O3/HZSM-5 catalyst has synergistic effects on upgrading the oxygenated pyrolysis vapours into higher contents of C6–C8 hydrocarbons (8.82%) in pyrolysis oil at 500 °C compared with other investigated catalysts. [ABSTRACT FROM AUTHOR]

This study assessed the effect of soil amendment with biochar on the production of some Mediterranean crops. Pine-derived biochar (B1) and partially pyrolyzed pine-derived biochar (B2) were used with a dose of 8 L/m2 in a corn crop, reporting a production increase of 38–270% over three years with B1, and no effect of B2 due to its poor quality. Olive stone-derived biochar (B3) was used in lavandin and vineyard crops with doses of 0.04–0.9 L/m2 and 0.37–2.55 L/m2, respectively. An increase of 23–25% in plant volume of lavandin was reported, while the production of grapes per plant was not significantly altered, although it increased by up to 66%. Soil analysis indicated that biochar does not significantly alter soil physicochemical parameters; therefore, biochar may affect plants by altering soil structure and increasing its cation exchange capacity and water management efficiency. Depending on its price, biochar application may be profitable for lavandin and corn crops, with a return-on-investment period ranging from 1 to 4 years. However, the profitability of its use in vineyards is questionable, particularly for the varieties with the lowest market price. Studies examining the economics of biochar application indicate that CO2 abatement certification may help in covering biochar application costs. [ABSTRACT FROM AUTHOR]

Three kinds of pore-forming agents (corn flour, starch, and biochar) were selected to prepare dolomite-based porous ceramic catalyst carriers with good mechanical properties. Pore-forming agents occupy space within preformed agglomerates, such that after the pyrolysis and sintering have been completed there are spaces within the resulting ceramic material. Porous ceramic samples prepared with biochar exhibited high apparent porosity and water absorption. By contrast, the apparent porosity of the porous ceramic samples prepared with starch as the pore-forming agent was low. When the ratio of the dolomite to quartz sand in the ceramic aggregate was changed from 4:6 to 3:7, the change of the apparent porosity of the porous ceramic samples made with starch as a pore-forming agent was very small, with high bulk density and compressive strength. Compared with corn flour and biochar, starch was less suitable as a pore-forming agent for porous ceramics. The apparent porosity and water absorption of the porous ceramics prepared with biochar as a pore-forming agent decreased slightly. But its bulk density and thermal conductivity were increased. This is mainly attributable to the fact that biochar is lighter, but it performs well in terms of mechanical strength and thermal conductivity.

The proposed Ni–M/sepiolite (SEP) catalysts (M=Ce, Pr, and La) were developed to improve syngas production in biomass pyrolysis. A homogeneous precipitation method was used to synthesize these catalysts. These catalysts were characterized using X-ray fluorescence, X-ray diffraction, scanning electron microscopy/energy-dispersive X-ray spectroscopy, and the Brunauer–Emmett–Teller method. A series of experiments were conducted to investigate the effects of catalyst types and M loading on gas composition and content in gas production. Simultaneously, the catalyst’s stability was tested. The experiments showed that the synthesized Ni–La/SEP catalyst with 12 wt% La and 20 wt% Ni loading had a high catalytic activity of improving gas quality compared with Ni–Pr/SEP, Ni–Ce/SEP, and Ni/SEP, giving a high hydrogen yield (41.18 vol.%) and CO yield (32.23 vol.%).