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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 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.

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.

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.

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.

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.

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 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.

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.

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.%).

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.

This study aims at optimizing the process conditions to extract maximum yields of bio-oil from pine sawdust using microwave-assisted pyrolysis (MAP). Aspen Plus® V11 was used to model the thermochemical conversion of pine sawdust to pyrolysis products, and response surface methodology (RSM) based on a central composite design (CCD) was employed in the optimization of the process parameters. The mutual effects of pyrolysis temperature and reactor pressure on the product distribution were investigated. The findings have shown that the optimal operating conditions for producing the highest amount of bio-oil (65.8 wt%) were achieved at 550 °C and 1 atm. The product distribution of the simulated model was more significantly influenced by linear and quadratic terms of the reaction temperature. In addition, a high determination coefficient (R2 = 0.9883) was obtained for the developed quadratic model. A set of three published experimental results acquired under circumstances comparable to the simulations' operating limitations were used to further validate the simulation results. The process’s economic viability was assessed in order to establish the bio-oil minimum selling price (MSP). A MSP of $1.14/L of liquid bio-oil was evaluated. An economic sensitivity analysis has shown that the annual fuel yield, required rate of return, annual income tax, annual operating costs and initial capital investment have a substantial impact on the MSP of bio-oil. It was inferred that using the optimized process parameters may improve the process' competitiveness on an industrial scale due to its better product yields and improved sustainability in biorefineries, as well as assure waste reduction.

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.

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 The purpose of this work was to transform a regional biowaste into value-added chemicals and products through a modest thermo-catalytic pyrolysis process. ZSM-11 (Zeolite Socony Mobile-11) zeolites modified by nickel (Ni) incorporation (1–8 wt%) were synthesized and characterized by means of X-Ray Diffraction, Inductively Coupled Plasma Atomic Emission Spectroscopy, Infrared Fourier Transform Spectroscopy, UV–Vis Diffuse Reflectance Spectra and Temperature Programmed Reduction. Results demonstrated that Ni was mainly incorporated as oxide. These porous materials were evaluated as heterogeneous catalysts to improve biooil composition. In this sense, higher hydrocarbon yields, and quality chemicals were obtained and oxygenates were diminished. The deactivation of the most active material was studied over six cycles of reaction. In order to achieve the circular bioeconomy postulates, the obtained biochar (usually considered a residue) was further transformed through a physicochemical activation. The obtained activated biochars were extensively characterized.

Biochar derived from pyrolysis or gasification has been gaining significant attention in the recent years due to its potential wide applications for the development of negative emissions technologies. A new concept was developed for biochar and power co-generation system using a combination of biomass pyrolysis (BP) unit, solid oxide fuel cells (SOFCs), and a combined heat and power (CHP) system. A set of detailed experimental data of pyrolysis product yields was established in Aspen Plus to model the BP process. The impacts of various operating parameters including current density (j), fuel utilization factor (Uf), pyrolysis gas reforming temperature (Treformer), and biochar split ratio (Rbiochar) on the SOFC and overall system performances in terms of energy and exergy analyses were evaluated. The simulation results indicated that increasing the Uf, Treformer, and Rbiochar can favorably improve the performances of the BP-SOFC-CHP system. As a whole, the overall electrical, energy and exergy efficiencies of the BP-SOFC-CHP system were in the range of 8–14%, 76–78%, and 71–74%, respectively. From the viewpoint of energy balance, burning the reformed pyrolysis gas can supply enough energy demand for the process to achieve a stand-alone BP-SOFC-CHP plant. In case of a stand-alone system, the overall electrical, energy and exergy efficiencies were 5.4, 63.9 and 57.8%, respectively, with a biochar yield of 31.6%.

This study investigates CO2 biofixation and pyrolytic kinetics of microalga G. pectorale using model-fitting and model-free methods. Microalga was grown in two different media. The highest rate of CO2 fixation (0.130 g/L/day) was observed at a CO2 concentration of 2%. The pyrokinetics of the biomass was performed by a thermogravimetric analyzer (TGA). Thermogravimetric (TG) and derivative thermogravimetric (DTG) curves at 5, 10 and 20°C/min indicated the presence of multiple peaks in the active pyrolysis zones. The activation energy was calculated by different model-free methods such as Friedman, Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), and Popescu. The obtained activation energy which are 61.7–287 kJ/mol using Friedman, 40.6–262 kJ/mol using FWO, 35–262 kJ/mol using KAS, and 66.4–255 kJ/mol using Popescu showed good agreement with the experimental values with higher than 0.96 determination coefficient (R2). Moreover, it was found that the most probable reaction mechanism for G. pectorale pyrolysis was a third-order function. Furthermore, the multilayer perceptron-based artificial neural network (MLP-ANN) regression model of the 4-10-1 architecture demonstrated excellent agreement with the experimental values of the thermal decomposition of the G. pectoral. Therefore, the study suggests that the MLP-ANN regression model could be utilized to predict thermogravimetric parameters.

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.

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.

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.

The kinetics of the pyrolysis of Brazil nut residues (Bertholletia excelsa), in this case, shells (BNS) and husks (BNH), were investigated via a thermogravimetric analysis in an inert atmosphere. The Flynn–Wall–Ozawa, Kissinger-Akahira-Sunose, Starink and Vyazovkin isoconversional models were used to estimate kinetic and thermodynamic parameters. The mean activation energy values ranged from 135.59 to 138.51 kJ/mol for the shells and from 151.94 to 153.92 kJ/mol for the husks in the active pyrolysis region. High values of the pre-exponential factor (>108 s−1) indicated the presence of complex reactions for both samples, which was confirmed in the analysis of the reaction mechanism using the master-plot method, through the multiple types of behavior during the variation of the conversion levels. Thermodynamic parameters, such as the enthalpy change, Gibbs free energy change and entropy change, characterized a nonspontaneous endothermic process, with little energy required. TG-MS analyses revealed less harmful gas emission behavior for the environment compared to fossil fuels. The results of the study, with an emphasis on its satisfactory higher heating value (13.8 and 14.6 MJ/kg), showed that Brazil nut residues, an Amazon Forest waste, have great potential in pyrolysis applications for the generation of renewable energy, which can contribute to forest preservation through the development of the circular bioeconomy.

A novel and effective experimental method for describing the evolution curves and hot maps of biomass pyrolysis vapors with the adjustment of sweeping gas flow rate was developed during condensation. The composition proportion of pyrolysis vapors was inverted from the composition quantification of segmental bio-oil recovered by the specific condenser with two flumes. The mathematical relationship between location and vapor composition was fitted by Slogistic function. The condensable proportion of water decreased from 85% to 60% as N2 flow rate increased from 100 mL/min to 500 mL/min under 340 K water bath. But 500 mL/min N2 flow rate accelerated the disturbance of condensing field and improved the recoveries of components with stronger condensing abilities than water. The condensable proportion of guaiacol and its derivatives decreased from 60% to 40% under 300 mL/min but increased to 55% under 500 mL/min. Furthermore, the evolution difference between high-proportion and low-proportion components in pyrolysis vapors in the condensing field was also discussed as well as the unique evolution of components with azeotrope phenomenon or special solubility. For the first time, the adjustment mechanism of constant non-condensable components on the evolution of condensable components was clarified during water bath condensation, which would remarkably improve the comprehension for the complex phase transition process during the selective condensation of biomass pyrolysis vapors.

Sustainable management of agricultural residues has gained momentum worldwide as an environmentally benign process. This study focused on the impact of pyrolysis temperature on biochars' physicochemical properties derived from two agricultural residue materials (pigeon pea stalk and bamboo) pyrolysed at different pyrolysis temperatures (400, 500 and 600 °C) for a holding time of 1 h. The bamboo and pigeon pea stalk were characterized, as well as their resulting biochar samples (proximate, ultimate, SEM, BET, FTIR and XRD). For both the biomass materials, biomass composition had great influence on the biochar yield and properties. More mass fraction of lignin in the bamboo biomass yields more biochar (32.20–27.00%) compared to pigeon pea stalk biomass (29.80–21.70%) at the same pyrolysis temperature. The mass fraction of fixed carbon of biochars was observed to be in the range of 81.85–85.68%, which were much higher than the biomass. The mass fraction of carbon in the derived biochars were in the range of 76.17–88.43%. The biochar with the highest mass fraction of carbon was found at a pyrolysis temperature of 600 °C for both biomass-derived biochars. Biochars with low atomic ratio of H/C (0.03–0.06) and O/C (0.09–0.25) confirmed their highly carbonized, aromatized and hydrophobic nature. The BET surface area of biochar samples were ranged from 16.90 to 307.10 m2 g−1, biochar with the higher surface area was obtained at pyrolysis temperature of 600 °C. At the same pyrolysis temperature, bamboo derived biochars were higher total pore volume (0.057–0.18 cm3 g−1) in respect to pigeon pea stalk derived biochars. The alkalinity of all biochars increased in tandem with the pyrolysis temperature and found to be in the range of 7.25–10.14. The acidic and polar functional groups were successively removed and resulted in a more hydrophobic well-organized carbon layered biochar at a temperature of 600 °C. The biochars were enriched with sylvite, calcite, and silicates of Mg, Mn, and Ca signifying its heterogonous characteristics and increased ash content.

Developing a kinetic model to analyze the multi-step reaction of biomass pyrolysis is pivotal to elucidate the mechanism of the pyrolysis. For this purpose, a model-fitting method such as multi-distribution the Distributed Activation Energy Model (DAEM) is one of the most reliable methods. DAEM with 4 different distribution functions of Gaussian, Logarithmic, Gumbel, and Cauchy was utilized to characterize the pyrolysis of cellulose and lignin during Thermogravimetric Analysis/Differential Scanning Calorimetry (TGA/DSC) instrumentation. By comparing Derivative Thermogravimetry (DTG) and DSC profiles, determination of pseudo-components can be done more accurately. A kinetics analysis on the pyrolysis of cellulose with a single Gaussian distribution DAEM yielded a single activation energy of 178 kJ mol−1 with a narrow standard deviation. This result was justified by a single and dominant endothermic peak followed by minor exothermic peaks in the DSC result. For lignin pyrolysis, the presence of multiple peaks is characterized by four pseudo-components in DAEM with activation energies of 157, 174, 194, and 200 kJ mol−1. These pseudo-components were confirmed by the DSC result which indicated the occurrences of two exothermic peaks with two lesser exothermic or possibly endothermic peaks at the same temperature range. These findings imply the importance of DSC to support a kinetics study of thermogravimetric pyrolysis.

This paper investigates the effect of non-linear thermal profile on the numerical solution of the multi-reaction model. According to the practical perspective, the temperature distribution at a different section of pyrolysis reactor is not necessarily following the ideal thermal history; therefore, it is necessary to predict the behaviour of the system for the higher degree of freedom. TG thermogram is obtained by the thermal degradation of pine needles sample in the thermogravimetric analyser (TGA). The activation energy, frequency factor, reaction order and the scale, shape and location parameters of a stochastic function are estimated for the non-linear parabolic thermal profile. The conventional Laplace integral is used to approximate the multi-reaction model. Activation energy obtained for the non-thermal profile lies in the range of 57.5–60 kJ·mol−1, whereas the frequency factor varies from 103–105 min-1. The obtained value of reaction order (n) lies in the domain of (0.9, 1.6).

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).

This study proposes to assess the effect of some relevant parameters of biomass pyrolysis on the numerical solutions of nthorder distributed activation energy model (DAEM) or multi reaction model (MRM). The two-step process mechanisms of pyrolysis is described by replacing the initial distribution function of f (E) with the Clayton copula. The upper limit (E∞) of ‘dE’ integral, activation energy (A), heating rate (m), and the shape and scale parameters of bivariate distribution function. Temperature ramp rate is assumed to vary linearly with time. Thermo-analytical data is obtained with the help of thermogravimetric (TG) analysis. Asymptotic technique is adopted to approximate double exponential and bivariate distribution function f (E1, E2), where E1and E2are the activation energies for bivariate scheme.

This paper studied the synergistic effects of catalyst mixtures on biomass catalytic pyrolysis in comparison with the single catalyst in a microwave reactor and a TGA. In general, positive synergistic effects were identified based on increased mass loss rate, reduced activation energy, and improved bio-oil quality compared to the case with a single catalyst at higher catalyst loads. 10KP/10Bento (a mixture of 10% K3PO4 and 10% bentonite) increased the mass loss rate by 85 and 45% at heating rates of 100 and 25°C/min, respectively, compared to switchgrass without catalyst. The activation energy for 10KP/10Bento and 10KP/10Clino (a mixture of 10% K3PO4 and 10% clinoptilolite) was slightly lower or similar to other catalysts at 30 wt.% load. The reduction in the activation energy by the catalyst mixture was higher at 100°C/min than 25°C/min due to the improved catalytic activity at higher heating rates. Synergistic effects are also reflected in the improved properties of bio-oil, as acids, aldehydes, and anhydrosugars were significantly decreased, whereas phenol and aromatic compounds were substantially increased. 30KP (30% K3PO4) and 10KP/10Bento increased the content of alkylated phenols by 341 and 207%, respectively, in comparison with switchgrass without catalyst. Finally, the use of catalyst mixtures improved the catalytic performance markedly, which shows the potential to reduce the production cost of bio-oil and biochar from microwave catalytic pyrolysis.

Abstract In Europe, and many parts of the world, the number and variety of animal species on farmland is in marked decline. There is a need to search for alternatives that are safe for the environmental and are effective in controlling weeds. Wood vinegar from biomass pyrolysis may be an alternative for herb control. In this study, Wood vinegar (WV) pH, moisture content, and composition were analyzed, with subsequent assessment of the effects of WV on nitrophilous plant communities under natural conditions. The following three treatments were used: WV dissolved in water to form 25 vol% and 50 vol% dilutions and undiluted WV (100 vol%). The results showed a greater than 70% decrease in biomass at 7 days after WV application in all treatments. At the end of the sampling period (day 42), the plots treated with WV had four‐times less biomass than the controls. No significant differences were observed among different treatments, thus indicating that a 25% dilution may suffice for use as an herbicide. However, this concentration also produced the highest variability in results. The area cleared by the affected species was colonized by perennial species. At the end of the sampling, 80% of the area of the treated plots was occupied by perennial species, whereas this percentage was 30% in control plots. Electron micrographs showed that the epidermis of the treated plants was severely affected within a few hours of the treatment, particularly of the stomatal cells. The most affected species were those with smooth leaves without protective structures and those with lighter stems and leaves. The good herbicidal performance of WV notwithstanding, regulations must be clarified for its use as an herbicide.

The key factor to reducing and controlling of CO2 from environment, which is the major contributor to global warming, is the use of alternative energy systems that can be used today and may be used in the future as green energy sources. Renewable resources currently account for about 9%-10% of energy consumed in the world and most of this is from hydropower and traditional biomass sources. Each of renewable energy technologies is in a different stage of development and commercialization and all have differences in current and future expected costs, resource availability and potential impact on energy supply. This paper discusses the potential for such integrated systems in response to the critical need for a cleaner energy technology. Several issues relating to renewable energies, environment and sustainable development are examined from both current and future perspectives. On the other hand, biomass is a potential energy resource that can be converted into different forms of energy or energy carrier, such as hydrogen. In this study, also non-conventional biomass sources such as rapeseed, rapeseed cake, and rapeseed meal, had been tested for hydrogen production from biomass pyrolysis process. The influence of biomass microstructure and reducing sugar content on the hydrogen production was studied through a high-energy ball-milling pre-process of the biomass source. The results indicate that the maximum production of hydrogen was obtained at 450°C independently of the biomass source. The biomass microstructure and reducing sugar content does not seem to have an effect on hydrogen production from biomass pyrolysis.

Catalytically active carbons derived from plant biomass are conducive to the construction of renewable energy source system and utilization of sustainable resources. In this article, natural cattail fibers are used to fabricate porous nitrogen-doped carbon via direct chemical activation and heteroatom modification treatments. The graphene-like sheets from biomass pyrolysis are assembled into three-dimensional carbon frameworks. The chemical activation of KHCO3 generated unique porous structure and N-containing molecules pyrolysis modification provided nitrogen doping atoms. High surface area up to 2,345 m2·g−1 with simultaneous hierarchical pores (from micro to meso and macro) with abundant edge defects are achieved for these carbon materials. These materials have a very large external surface area up to 1,773 m2·g−1. The above strategy exhibits a significant synergistic effect on the improvement of catalytic properties toward hydrogen evolution reaction and oxygen reduction reaction. The small over potentials and Tafel slopes of these catalytically active carbons demonstrate excellent potential applications in renewable energy conversion and storage systems. This research established a new link among environmental improvement, biomass conversion and renewable energy utilization.

This paper deals with pyrolysis decomposition of Cedrus deodara leaves with the help of thermogravimetric analysis (TGA). Experiments are performed in the presence of inert atmosphere of nitrogen. Experiments are conducted at three different heating rates of 5 °C∙min-1, 10 °C∙min-1 and 15 °C∙min-1 within temperature range of 35 °C to 700 °C. Arrhenius parameters such as activation energy and frequency factor are estimated by Flynn Wall and Ozawa (FWO), Kissinger-Akahira-Sonuse (KAS) and Kissinger. The activation energy and frequency factor calculated by using Kissinger method are 67.63 kJ∙mol-1 and 15.06 . 104 min-1 respectively; whereas the averaged values of the same parameters through FWO and KAS methods are 89.59 kJ∙mol-1 and 84.748 kJ∙mol-1, 17.27 . 108 min-1 and 62.13 . 107 min-1 respectively. Results obtained through Kissinger method represent the actual values of kinetic parameters. Conversely, FWO and KAS methods reflect the apparent values of kinetic parameters, as they are highly influenced by the overlapping of competitive reactions occur during pyrolysis.

A kinetic study of pyrolysis process of Parthenium hysterophorous is carried out by using thermogravimetric analysis (TGA) equipment. The present study investigates the thermal degradation and determination of the kinetic parameters such as activation E and the frequency factor A using model-free methods given by Flynn Wall and Ozawa (FWO), Kissinger-Akahira-Sonuse (KAS) and Kissinger, and model-fitting (Coats Redfern). The results derived from thermal decomposition process demarcate decomposition of Parthenium hysterophorous among the three main stages, such as dehydration, active and passive pyrolysis. It is shown through DTG thermograms that the increase in the heating rate caused temperature peaks at maximum weight loss rate to shift towards higher temperature regime. The results are compared with Coats Redfern (Integral method) and experimental results have shown that values of kinetic parameters obtained from model-free methods are in good agreement. Whereas the results obtained through Coats Redfern model at different heating rates are not promising, however, the diffusion models provided the good fitting with the experimental data.

This study focuses on the influence of some of the relevant parameters of biomass pyrolysis on a fuzzified solution of the Distributed Activation Energy Model (DAEM) due to randomness and inaccuracy of data. The study investigates the fuzzified Distributed Activation Energy Model using the fuzzy Weibull distribution. The activation energy, frequency factor, and distribution variables of the 3-parameter Weibull analysis are converted into a non-crisp set. The expression for the fuzzy sets, and their α-cut are discussed with an initial distribution for the activation energies following the Weibull distribution function. The thermo-analytical data for pine needles is used to illustrate the methodology to exhibit the fuzziness of some of the parameters relevant to biomass pyrolysis.

The main aim of this paper pivoted around the influence of some parameters relevant to biomass pyrolysis on the numerical solutions of the n th order distributed activation energy model (DAEM) using the Gamma distribution. The upper limit of ‘dE’ integral, frequency factor, reaction order, and the shape and rate parameters of the Gamma distribution are investigated. Analysis of the mathematical model is done with the help of asymptotic expansion.

The routine pruning and cutting of fruit trees provides a considerable amount of biowaste each year. This lignocellulosic biomass, mainly in the form of branches, trunks, rootstocks, and leaves, is a potential high-quality fuel, yet often is treated as waste. The results of a feasibility study on biochar production by pyrolysis of residues from orchard pruning were presented. Three types of biomass waste were selected as raw materials and were obtained from the most common fruit trees in Poland: apple (AP), pear (PR), and plum (PL) tree prunings. Two heating rates and three final pyrolysis temperatures were applied. For the slow (SP) and fast pyrolysis (FP) processes, the heating rates were 15 °C/min and 100 °C/min, respectively. The samples were heated from 25 °C up to 400, 500, and 600 °C. Chemical analyses of the raw materials were conducted, and the pyrolysis product yields were determined. A significant rise of higher heating value (HHV) was observed for the solid pyrolysis products, from approximately 23.45 MJ/kg for raw materials up to approximately 29.52 MJ/kg for pyrolysis products at 400 °C, and 30.53 MJ/kg for pyrolysis products at 600 °C. Higher carbon content was observed for materials obtained by fast pyrolysis conducted at higher temperatures.

This paper deals with the influence of some parameters relevant to biomass pyrolysis on the numerical solutions of the nonisothermal nth order distributed activation energy model using the Rayleigh distribution. Investigated parameters are the integral upper limit, the frequency factor, the heating rate, the reaction order and the scale parameters of the Rayleigh distribution. The influence of these parameters has been considered for the determination of the kinetic parameters of the non-isothermal nth order Rayleigh distribution from the experimentally derived thermoanalytical data of biomass pyrolysis.

This paper proposes the study of the application of fuzzy logic on the relevant parameter of biomass pyrolysis. The frequency factor, the upper limit of ‘dE’, and the scale and shape parameters of the fuzzy Gamma distribution were fuzzified in order to estimate randomness and to accommodate realistic values. The distribution function, f (E), of the activation energies was assumed to follow the fuzzy Gamma distribution. Thermo-analytical data was found experimentally with the help of TGA/DTG analysis. The approximated solution of the DAEM was obtained using the asymptotic approach.

As part of the strive for a carbon neutral energy production, biomass combustion has been widely implemented in retrofitted coal burners. Modeling aids substantially in prediction of biomass flame behavior and thus in boiler chamber conditions. In this work, a simple model for devolatilization of biomass at conditions relevant for suspension firing is presented. It employs Arrhenius parameters in a single first order (SFOR) devolatilization reaction, where the effects of kinetics and heat transfer limitations are lumped together. In this way, a biomass particle can be modeled as a zero dimensional, isothermal particle, facilitating computational fluid dynamic calculations of boiler chambers. The zero dimensional model includes the effects of particle aspect ratio, particle density, maximum gas temperature, and particle radius. It is developed using the multivariate data analysis method, partial least squares regression, and is validated against a more rigorous semi-2D devolatilization model. The model has the capability to predict devolatilization time for conditions in the parameter ranges; radius (39–1569 μμm), density (700–1300 kg/m3), gas temperature (1300–1900 K), aspect ratio (1.01–8). Results show that the particle radius and gas phase temperature have a large influence on the devolatilization rate, and the aspect ratio has a comparatively smaller effect, which, however, cannot be neglected. The impact of aspect ratio levels off as it increases. The model is suitable for use as stand alone or as a submodel for biomass particle devolatilization in CFD models.

Valorising biomass waste and producing renewable energy or materials is the aim of several conversion technologies. In this work, we consider two residues from different production chains: lignocellulosic residues from agriculture and wool residues from sheep husbandry. These materials are produced in large quantities, and their disposal is often costly and challenging for farmers. For their valorisation, we focus on slow pyrolysis for the former and water hydrolysis for the latter, concisely presenting the main literature related to these two processes. Pyrolysis produces the C-rich biochar, suitable for soil amending. Hydrolysis produces a N-rich fertiliser. We demonstrate how these two processes could be fruitfully integrated, as their products can be flexibly mixed to produce fertilisers. This solution would allow the achievement of balanced and tuneable ratios between C and N and the enhancement of the mechanical properties. We propose scenarios for this combined valorisation and for its coupling with other industries. As a result, biomass waste would be returned to the field, following the principles of circular economy.

This article focuses on the influence of relevant parameters of biomass pyrolysis on the numerical solution of the isothermal nth-order distributed activation energy model (DAEM) using the Rayleigh distribution as the initial distribution function F(E) of the activation energies. In this study, the integral upper limit, the frequency factor, the reaction order and the scale parameters are investigated. This paper also derived the asymptotic approximation for the DAEM. The influence of these parameters is used to calculate the kinetic parameters of the isothermal nth-order DAEM with the help of thermo-analytical results of TGA/DTG analysis.

Pine wood pyrolysis vapors were catalytically treated using Zeolite catalysts. An auger fed reactor was used for the pinewood pyrolysis while a packed bed reactor mounted on the top of the auger reactor housed the catalyst for the treatment of pinewood pyrolytic vapors. The pyrolytic vapors produced at 450 oC were passed through zeolite catalysts maintained at 425 oC at a weight hourly space velocity (WHSV) of 12 h-1. Five zeolites, including ZSM-5, mordenite, ferrierite, Zeolite-Y, and Zeolite-beta (all in H form), were used to study the effect of catalyst properties such as acidity, pore size, and pore structure on catalytic cracking of pinewood pyrolysis vapors. Product bio-oils were analyzed for their chemical composition using GC-MS, water content, density, viscosity, acid value, pH, and elemental compositions. Thermogravimetric analysis (TGA) was performed to analyze the extent of coking on zeolite catalysts. Application of catalysis to biomass pyrolysis increased gas product yields at the expense of bio-oil yields. While all the zeolites deoxygenated the pyrolysis vapors, ZSM-5 was found to be most effective. The ZSM-5 catalyzed bio-oil, rich in phenolics and aromatic hydrocarbons, was less viscous, had relatively lower acid number and high pH, and possessed oxygen content nearly half that of un-catalyzed bio-oil. Brønsted acidity, pore size, and shape-selective catalysis of ZSM-5 catalyst proved to be the determining factors for its activity. TGA results implied that the pore size of catalysts highly influenced coking reactions. Regeneration of the used catalysts was successfully completed at 700 oC.

Pyrolysis processes of typical biomass, such as corn stalk and birch chips, were investigated by thermogravimetric analysis (TGA). The apparent activation energy and pre-exponential factor were calculated with the adoption of the improved Coats-Redfern integral method, 46 types of common mechanism functions, and the least square and iterative methods. By applying basic parameters of biomass pyrolysis, a reaction rate constant, activation entropy and activation enthalpy, activation Gibbs free energy, and the steric-hindrance factor were all calculated. Results showed that biomass pyrolysis can be divided into two primary reaction zones (Event 3 and Event 4). Event 3 is focused by cellulose and hemicellulose. Event 4 is oriented by lignin and cellulose. The thermogravimetric curves of the two biomass types under carbon dioxide and nitrogen atmospheres were roughly similar. The reaction mechanism function is 1 - alpha. It is possible to use activation entropy to represent the pre-exponential factor and to use the steric hindrance factor to predict the reaction rate.

This article covers new application for char as a carrier of phase-change materials (PCM) that could be used as an additive to building materials. Being composed of bio-char and PCM, the granulate successfully competes with more expensive commercial materials of this type, such as Micronal® PCM. As a PCM carrier, char that was obtained from the pyrolysis of chestnut fruit (Aesculus hippocastanum) with different absorbances of the model phase-change material, Rubitherm RT22, was tested. DSC analysis elucidated several thermal properties (such as enthalpy, phase transition temperature, and temperature peak) of those mixtures and the results were compared with a commercial equivalent, Micronal DS 5040 X. Comparative research, approximating realistic conditions, were also performed by cooling and heating samples in a form of coatings that were made from chars with different content of RT22. These results indicated that the use of char as a PCM carrier was not only possible, but also beneficial from a thermodynamic point of view and it could serve as an alternative to commercial products. In this case, adsorption RT22 into char allowed for temperature stabilization comparable to Micronal DS 5040 X with ease of use as well as the economic advantages of being very low cost to produce due to microencapsulation. Other advantage of the proposed solution is related with the application of char obtained from waste biomass pyrolysis as a PCM carrier, and using this product in building construction to improve thermal comfort and increase energy efficiency.

In the upgrading of biomass pyrolysis vapors to hydrocarbons, dehydration accomplishes a primary objective of removing oxygen, and acidic zeolites represent promising catalysts for the dehydration reaction. Here, we utilized density functional theory calculations to estimate adsorption energetics and intrinsic kinetics of alcohol dehydration over H-ZSM-5, H-BEA, and H-AEL zeolites. The ONIOM (our Own N-layered Integrated molecular Orbital and molecular Mechanics) calculations of adsorption energies were observed to be inconsistent when benchmarked against QM (Quantum Mechanical)/Hartree−Fock and periodic boundary condition calculations. However, reaction coordinate calculations of adsorbed species and transition states were consistent across all levels considered. Comparison of ethanol, isopropanol (IPA), and tert-amyl alcohol (TAA) over these three zeolites allowed for a detailed examination of how confinement impacts on reaction mechanisms and kinetics. The TAA, seen to proceed via a carbocationic mechanism, was found to have the lowest activation barrier, followed by IPA and then ethanol, both of which dehydrate via a concerted mechanism. Barriers in H-BEA were consistently found to be lower than in H-ZSM-5 and H-AEL, attributed to late transition states and either elevated strain or inaccurately estimating long-range electrostatic interactions in H-AEL, respectively. Molecular dynamics simulations revealed that the diffusivity of these three alcohols in H-ZSM-5 were significantly overestimated by Knudsen diffusion, which will complicate experimental efforts to develop a kinetic model for catalytic fast pyrolysis.

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