Thermochemical Conversion Of Biomass Research Articles

Multi-objective optimization of a dual fuel CI engine powered with syngas and pilot diesel using TLBO algorithm: A metaheuristic approach

Abstract The thermochemical conversion of biomass into producer gas presents an attractive alternative fuel option for compression ignition (CI) engines, making biomass gasification a critical driver for achieving sustainable development goals. Considering the application of producer gas (PG) in CI engine, the most potential gases include H2 and CO as main fuel compounds and it is crucial to comprehensively understand the impact of these two gas components on the engine behaviour. Nowadays, artificial intelligence-powered models are frequently applied for simulating engines that run on a single type of fuel. However, their usage is not as common when it comes to modeling dual-fuel CI engines run on synthetic producer gas or syngas. The present study explores the feasibility of optimizing operational parameters, such as engine load and syngas composition, in improving the efficiency and lowering the levels of pollutants emitted by a 3.5 kW CI engine operated under dual fuel (DF) mode using syngas as primary fuel and diesel as pilot fuel. The performance and emission characteristics of syngas (H2:CO) is examined by studying its behaviour in four different combinations. The compositions of syngas are prepared based on the volumetric percentage of the H2 and CO and is inducted into the combustion chamber using a novel venturi-type air-gas mixer. In the present study, an intelligent metaheuristics-based optimization algorithm i.e., Teaching–Learning Based Optimization (TLBO) is developed and introduced, to develop a predictive model within constrained range of engine operating conditions. Further, the algorithm is used to estimate multiple engine performance characteristics simultaneously viz., brake thermal efficiency (BTE), unburned hydrocarbons (HC), and carbon monoxide (CO). The resultant findings identify the optimal engine load of 68.87% and the ideal syngas composition of 63.9% H2 and 49.5% CO as key parameters for maximizing engine efficiency while minimizing exhaust emission. At these optimized operating condition, 19.49% BTE is observed, while HC and CO emission was found to be 384.6 ppm and 445.33 ppm respectively. This shows the effective and efficiency of the proposed algorithm.

Efficient Glucose Isomerization to Fructose using Photoregenerable MgSnO3 Catalyst with Cooperative Acid-Base Sites.

The isomerization of glucose to fructose plays a crucial role in the food industry and the production biomass-derived chemicals in biorefineries. However, the catalyst used in this reaction suffers from low selectivity and catalyst deactivation due to carbon or by-product deposition. In this study, MgSnO3 catalyst, synthesized via a facile two-step process involving hydrothermal treatment and calcination, was used for glucose isomerization to fructose. The catalyst demonstrated outstanding catalytic performance, achieving a fructose equilibrium yield of 29.8% with a selectivity exceeding 90% under mild conditions owing to its acid-base interaction. Notably, spent catalysts can be regenerated by photoirradiation to remove surface carbon, thereby avoiding the changes in properties and subsequent loss of activity associated with conventional calcination regeneration method. This novel approach eliminates the energy consumption and potential structural aggregation associated with traditional calcination regeneration methods. The acid-base active sites of the catalyst, along with their corresponding catalytic reaction mechanism and photoregeneration mechanism were investigated. This study presents a demonstration of the comprehensive utilization of catalytic material properties, i.e., acid-base and photocatalytic functionalities, for the development of a green and sustainable biomass thermochemical conversion system.

Atlas of Microscopic Images of Biochar

Derived through the thermochemical conversion of biomass, biochar is a carbon-rich substance recognized for its significance in environmental applications and sustainable agriculture. As interest in its utilization continues to rise, it becomes crucial to comprehend how the source material and pyrolysis parameters influence the properties of biochar and, consequently, to research the suitability of various analytical methods for characterizing it. Despite the current utilization of numerous physical and chemical methods, the untapped potential of reflected light microscopy warrants further exploration. While a few recent studies suggest a correlation between certain microscopic characteristics and selected physical and chemical properties of biochar, the data are limited and difficult to compare. This is primarily due to variations in the types of original biomass used and lack of information about pyrolysis conditions. Moreover, because only a limited number of photographs taken under a reflected light microscope are publicly available to-date, it is difficult to evaluate morphological differences between various biochars and other organic materials such as inertinites from coal, charcoal, etc. To address limited availability of publicly available data, this “Atlas of Microscopic Images of Biochar” presents a collection of more than 300 images contributed by researchers from Poland, the United States, Canada, Australia, Brazil, and Denmark. These photomicrographs capture optical characteristics of a diverse array of biochar, demonstrating its unique morphological and structural features. This visual documentation can serve as a valuable resource for researchers, industry professionals, educators, and enthusiasts interested in investigating the complexities of biochar forms.

Tailoring microwave frequencies for high-efficiency hydrogen production from biomass

Generating green hydrogen through biomass thermochemical conversion is pivotal for contributing to carbon neutrality. However, the efficiency of hydrogen production is hindered by the byproduct of tar formed during biomass depolymerization. This study employed a variable-frequency microwave ranging from 2430 to 6000 MHz to investigate the influence of microwave frequency on tar removal and hydrogen recovery over activated charcoal (AC). Experimental results indicated that microwave frequencies significantly impact the temperature distribution and heating rates of AC. Notably, at 4640 MHz the AC rapidly reached 1145 °C within seconds, with an instantaneous heating rate of 2022 °C/min. The ultra-fast heating rate crucially contributes to achieving 100 % efficiency in tar cracking, resulting in a hydrogen yield of 32.8 mmol/g. With a hydrogen recovery rate surpassing 94 %, the 4640 MHz frequency represents a 15.4-fold increase compared to the conventional 2450 MHz. This innovative approach holds significant promise for enhancing energy efficiency in the pursuit of carbon-neutral energy production.

Review of Methods for Converting Biomass into Biofuels

Thermochemical processes are among the most effective methods of obtaining hydrogen-rich gases from biomass. These technologies mainly include pyrolysis, gasification and hydrothermal liquefaction. Thermochemical conversion of dry biomass is similar to the conversion of fossil fuels using gasification and pyrolysis methods. Products obtained through thermochemical processes (CO and CH4) can be processed into other biofuels, e.g. syngas, a raw material for producing synthetic hydrocarbons, methanol and alcohols. In recent years, advanced research has been carried out using biomass to produce liquid fuels. The biomass pyrolysis process in the presence of a catalyst is based on the rapid heating of the biomass to a temperature of approximately 500°C in the so-called inert atmosphere in which there are no reactive gases. This process produces a liquid product: pyrolysis oil, gas and charcoal. The bio-oil produced in this process constitutes 60-75% of the mass of the biofuel and is thermally unstable because it contains up to 300 different chemical compounds. However, the bio-oil obtained in this way is incompatible with conventional liquid transport fuels (gasoline, diesel) due to its high oxygen content. Pyrolysis in the presence of a zeolite catalyst is a process that allows for the effective conversion of biomass in economic and ecological terms. A zeolite catalyst makes it possible to remove oxidized compounds in situ and modify the properties of the biofuel to ensure its compatibility with conventional transport fuels. The catalyst plays a crucial role in this process because it removes oxygen from oxygenates and, consequently, creates stable reaction products that can then be treated to obtain renewable transport fuels or other useful chemicals. The article presents methods of biomass conversion via pyrolisis, microorganisms usage, zeolite-based catalysis, biocatalysis and photo-fermentation, which poses a big possibility of diversification of renewable energy sources.

Remediation of mine overburden and contaminated water with activated biochar derived from low-value biowaste

BackgroundMines can be regarded as the economic backbone of India with a contribution of 10–12 % towards the gross domestic production with industrial demand. It gives rise to environmental problems like soil, water and air pollution. The active mines generate lots of waste rock and wastewater that contaminate nearby soil and water bodies with heavy metals. MethodsThe elimination of heavy metals by suitable amendments is emerging as a potential solution to such problems. Biochar, a carbon rich, stable, alkaline and porous product of thermo-chemical conversion of biomass has emerged as a promising adsorbent of heavy metals. Conversion of these biowastes into biochar is a sustainable approach as it fulfills multiple objectives of waste utilization, and pollution abatement. Significant findingsDue to its large surface area, biochar can restrain heavy metals while modified biochar has an increased potential for adsorption with an increased surface area. The review emphasizes the type of mines, overburden generation, their impact on soil and water, and the utility of different biowastes available to be mobilized into biochar for remediation of contaminated water and soil. It also bridges the gap in the current knowledge on the activation techniques of biochar with heavy metals remediation.

Kinetic and quantitative analysis of gaseous products of thermochemical biomass conversion based on thermogravimetric and mass‐spectrometric data

AbstractThe aim of this study is to apply a new approach to the quantitative analysis of the formation of gaseous products generated during the thermochemical conversion of wood waste samples of different fineness by using thermogravimetric analysis with mass spectrometry (TGA‐MS). Profiles of the release of gaseous components in the process of thermochemical conversion of wood samples were obtained based on data from the combined use of mass spectrometry and thermogravimetry. The resulting mass spectrometric data were processed according to the proposed methodology and the characteristics of the released gases were noted. The kinetic coefficients of the gases’ formation were calculated from the processed data.

Impact of high-temperature biomass pyrolysis on biochar formation and composition

The development and utilization of biomass play a vital role in reducing fossil fuel dependency and mitigating greenhouse gas emissions. High-temperature pyrolysis provides a promising route for converting biomass into valuable products without tar formation. Kinetic models are essential for understanding biomass pyrolysis processes, aiding reactor design and optimization. In this study, rice husk (RH) and corn straw (CS) are selected, which exhibit significant differences in ash content but are widely present. Pyrolysis is performed using a thermogravimetric analyzer coupled with a mass spectrometer (TGA-MS). The results show a rapid decrease in solid residue oxygen content at elevated temperatures, which stabilized after reaching 900°C, accounting for about 8–10%. MS quantification indicates increased release of H2O and CO during this stage. Fourier transform infrared spectroscopy (FTIR) analysis on the biochar unveils that this phenomenon is attributed to the stretching vibration of C-O bonds and the conversion of -OH groups. The remaining oxygen primarily exists as carbonyl and carboxyl groups. Subsequently, the CRECK-S-B biomass pyrolysis kinetic model is updated, specifically targeting the transformation mechanism of oxygen-containing solids at high temperatures to improve the prediction of biochar yield and elemental composition. The relative error of oxygen content prediction is less than 10%. The accuracy of the model is validated through experimental data and an extensive literature database, leading to the establishment of a comprehensive database. The updated model demonstrates significantly enhanced prediction accuracy for pyrolysis temperatures above 800°C, expanding its applicability range. Moreover, it achieves an accuracy rate exceeding 80% for char yield and elemental content in the temperature range of 200–1000°C, including torrefaction conditions. It provides a theoretical foundation for the effective utilization of high-temperature biochar, offers a novel insight into biomass thermochemical conversion, and contributes to the sustainable development of biomass energy.

Coupling coarse‐grained DEM‐CFD and intraparticle model for biomass fast pyrolysis simulation and experiment validation

AbstractThe 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.

Assessment and modeling of mercury adsorption on carbon-based adsorbents prepared from Jacaranda mimosifolia and guava biomass via pyrolysis and hydrothermal carbonization

Abstract The mercury adsorption properties of carbon-based materials prepared from jacaranda (Jacaranda mimosifolia) and guava (Psidium guajava) seed wastes are reported and compared in this paper. These adsorbent samples were obtained via pyrolysis and hydrothermal carbonization. Mercury adsorption equilibrium was studied at pH 4 and 20–40 °C, and the adsorption enthalpy changes were calculated for all adsorbent samples. The results showed that jacaranda-based materials contained a higher amount of acidic functional groups than guava seed-based adsorbents, and consequently, their mercury adsorption properties were better. The surface area of these adsorbents was <10 m2/g thus being classified as low-porosity materials. Elemental analysis indicated that all adsorbents were mainly composed of oxygen (4–25%) and carbon (75–95%). The calculated adsorption capacities at saturation of the best adsorbent were 18.05–30.09 mg/g under the tested experimental conditions. Statistical physics calculations also indicated that the adsorption mechanism of HgCl2 species was multi-molecular and endothermic. Ligand exchange and van der Waals forces were involved in generating the mercury–adsorbent interface. These results highlight the importance of comparing and optimizing biomass thermochemical conversion routes to tailor the surface properties of adsorbents used for water purification.

Prediction of bio-oil yield by machine learning model based on 'enhanced data' training

Bio-oil is widely used and has great application potential. With the development of artificial intelligence, machine learning has been gradually applied in the field of biomass, the data augmentation method is a common operation method for training models in the field of computer or data processing. In this study, the concept of 'enhanced data' was proposed for the first time. According to the composition characteristics of biomass raw materials, the sample data were divided into three different sample sets. Based on the light gradient boosting machine (Light GBM) and deep neural network (DNN) algorithm, a prediction model of bio-oil yield was established. Combined with the analysis of partial correlation, the influence of 'enhanced data' on the prediction accuracy of the model was explored. The results showed that the prediction accuracy of the model was improved to a certain extent after adding 'enhanced data'. The Light GBM model was more suitable for predicting bio-oil yield, and the Light GBM _ c model performed best, with R2 of 0.894, MAE of 3.622, and RMSE of 4.445. At the same time, this study also has certain reference significance for other prediction studies in the field of biomass thermochemical conversion.

Advancements, Challenges, and Pathways to Sustainable Biofuel Production

AbstractThe discovery of new energy sources plays a vital role to fulfil the needs of energy and depletion of fossil fuel sources. An inclusive review of all available technologies for the synthesis of biofuels from biomass is presented. Amongst the innovative biomass conversion technologies, thermochemical technology encompasses significant potential practices and is required for expansion. Universally, biofuels are gaining importance due to the depletion of non‐renewable fuel sources in transport and industries by equivalent work proficiencies. The reaction mechanism thoroughly explores all aspects associated with reaction conditions, types of reactor, and products. Biomass thermochemical conversion technologies will be influential in producing sustainable biofuels.

Hydrothermal Carbonization of Waste Biomass: A Review of Hydrochar Preparation and Environmental Application

The concept of a bio-based economy has been adopted by many advanced countries around the world, and thermochemical conversion of waste biomass is recognized as the most effective approach to achieve this objective. Recent studies indicate that hydrothermal carbonization (HTC) is a promising method for the conversion of waste biomass towards novel carbonaceous materials known as hydrochars. This cost-effective and eco-friendly process operates at moderate temperatures (180–280 °C) and uses water as a reaction medium. HTC has been successfully applied to a wide range of waste materials, including lignocellulose biomass, sewage sludge, algae, and municipal solid waste, generating desirable carbonaceous products. This review provides an overview of the key HTC process parameters, as well as the physical and chemical properties of the obtained hydrochar. It also explores potential applications of produced materials and highlights the modification and functionalization techniques that can transform these materials into game-changing solutions for a sustainable future.

Optimization of the Product Yields of the Pyrolysis of Palm Kernel Shell in a Fixed-Bed Reactor Using Response Surface Methodology (RSM)

Pyrolysis is a method used for the thermochemical conversion of biomass and agro wastes into three major by-products namely, biochar, bio-oil, and biogas in the absence of oxygen. Global waste generation is increasing at an alarming rate. Palm kernel shell (PKS) is among the palm wastes accumulating in many palm oil mills around the globe with the attendant problems in waste management. The utilization of coal for energy generation is more expensive and not environmentally friendly. Bio-oil refineries and industries require the utilization of minimum resources (input) to achieve optimal response (output) in the production process. However, more than 30% of the energy content derivation from the pyrolysis process is wasted due to nonoptimization of the process parameters. This study investigated the optimization of the product yields of the pyrolysis of PKS in a fixed-bed batch reactor using response surface methodology (RSM). Masses of 1 kg, 2 kg, and 3 kg were pyrolyzed in batches at process temperature variations of 200 OC, 300 OC, 400 OC, and 500 OC. Design Expert 12 software (Version 12.0.3.0 Stat-Ease Inc. MN, USA) and Analysis of Variance (ANOVA) were used for the statistical analysis. Lack-of-fit, adjusted, and predicted multiple correlation coefficients and coefficient of variation of the different polynomial models were compared to select the best-fitting polynomial model. The optimal feedstock parameters were 2.66 kg of PKS and 410.0 OC process temperature. The predicted results were 0.986 kg of biochar, 1.205 kg of bio-oil, 0.481 kg of biogas, 1116.5 cm3 of bio-oil, and 140.6 minutes. The experimental results were 0.894 kg of biochar, 1.316 kg of bio-oil, 0.498 kg of biogas, 1208.9 cm3 of bio-oil, and at 162.8 minutes through validation. The validated quadratic model was suitable for the optimization and RSM is a numerical, statistical, and mathematical tool for modeling and optimization of the pyrolysis process in a fixed-bed batch reactor.

Thermochemical conversion of biomass to fuels and chemicals: a review of catalysts, catalyst stability, and reaction mechanisms

ABSTRACT Woody biomass can be converted into a synthesis gas, a mixture of H2, CO, and CO2, by gasification. Removal of refractory tars, produced during biomass gasification, requires highly active catalysts that can be applied in-situ during gasification or in secondary catalytic tar cracking reactors. Subsequently, the water-gas-shift (WGS) reaction adjusts the H2 to CO ratio, prior to the synthesis of the desired products (CH4 as renewable natural gas or RNG, alcohols, hydrocarbons, and olefins). Catalysts play a pivotal role in all processing steps, with recent advances in catalyst development discussed herein with an emphasis on catalyst stability, reaction mechanisms, and structure–activity relationships. The economic viability of biomass conversion to fuels and chemicals is also reviewed and shown to be dependent on end-product, location, and government incentives.

Physicochemical Characterization of Woody Lignocellulosic Biomass and Charcoal for Bio-energy Heat Generation

Biomass and its interactions for heat generation have received little attention. In this study, the woody biomass materials were Prosopis africana (PA), Harungana madascariences (HM), Vitrllaria paradoxa (VP), and Afzelia africana (AA). The composition (extractives, carbohydrate, and lignin) of the biomass was determined. The biomass was converted to charcoal in a traditional kiln. A thermo-kinetic examination of the charcoal samples was carried out. The kinetic parameters and potential reaction mechanisms involved in the decomposition process were both obtained using the integral (Flynn–Wall Ozawa) isoconversional methods in conjunction with the Coats-Redfern approach. The activation energy profiles for the charcoal samples in oxidizing atmospheres were 548 kJ/mol for AA, 274 kJ/mol for VP, 548 kJ/mol for PA, and 274 kJ/mol for HM. All charcoal samples underwent comprehensive, multi-step, complex reaction pathways for thermal degradation. The charcoal samples exhibit not only great potential for biochemical extraction but also for bioenergy applications. The significant amount of combustion characteristics in the raw biomass and charcoal samples indicates that each type of wood charcoal produced has more fixed carbon, less ash, and less volatile matter, all of which are desirable for the thermo-chemical conversion of biomass for the production of heat.

Upgrading of biomass-derived solar hydrothermal bio-oils through catalytic hydrodeoxygenation in supercritical ethanol

The use of concentrated solar energy as the heat source to perform hydrothermal liquefaction (HTL) of biomass is a promising alternative to improve the thermal efficiency of the process and reduce the environmental impact of the use of fossil fuels. However, the HTL of lignocellulosic biomass produces a bio-oil that still requires an upgrading treatment to improve its properties as fuel. In the present work, bio-oils obtained from solar hydrothermal liquefaction of Agave and corncob were upgraded for the first time by hydrodeoxygenation (HDO) in supercritical ethanol using a Mo2C catalyst supported in carbon nanofibers. The main results showed yields up to 69% of the upgraded bio-oil and a deoxygenation grade of 71%, with HHV values around 35 MJ/kg for most of the upgraded bio-oils. Moreover, it was observed that HDO treatment of the solar bio-oils can produce upgraded bio-oils with chemical properties and yields similar to those produced by conventional thermochemical methods, which opens the door to extend the use of concentrated solar technologies for the whole process: from biomass thermochemical conversion to its upgrading into drop-in fuels.

X-ray imaging techniques for gas–solid fluidized beds: A technical review

Gas–solid fluidized beds have historically been employed in a variety of fields owing to the excellent mixing they provide, which can enhance chemical reaction rates and make the control of the reactor temperature easier than other technologies. Due to this wide application, heuristic knowledge of their functioning has been accumulating over the years. This knowledge, however, is not always backed by a deep understanding of the physical phenomena occurring in such systems. While this heuristic knowledge is sufficient to operate fluidized beds, operation optimization and scale-up are much harder to perform. A range of diagnostic techniques have been applied over the years to draw information about the inner workings of fluidized beds. Among these, x-ray imaging techniques, especially x-ray digital radiography and x-ray computed tomography, stand out for the kind and quality of information they can provide. Their high penetrating power enables visualization of phenomena taking place in the bulk of a fluidized bed, without disturbing the bed hydrodynamics. Furthermore, x rays are generated by a source that can be switched off, making them inherently safer than other imaging techniques relying on radioactive sources, such as γ-ray computed tomography. This work gives an overview of the techniques themselves, of the quantities they can measure, and of some modern applications of gas–solid fluidized beds they have been applied to, such as waste treatment and thermochemical conversion of biomass. Overall, x-ray digital radiography and x-ray computed tomography are better suited for process understanding than for process monitoring and are extremely useful in the study of voidage distribution and macro structures, such as bubbles and jets.

CFD-DEM investigation of the flow characteristic of biomass particles and heat carrier in a novel V-shaped down-tube pyrolysis reactor

During biomass thermochemical conversion, addition of inert heat carriers such as sand, metal and ceramic balls into the reactor can effectively promote the flow mixing and conduction heat transfer of biomass. Therefore, it is important to understand the flow behavior of the binary mixture containing biomass and heat carrier for efficient utilization of biomass energy. In this study, computational fluid dynamics and discrete element method (CFD-DEM) were used to evaluate the flow behavior and law of the binary mixture of heat carrier and biomass in a novel down-tube pyrolysis reactor. The results show important effects of different ceramic ball sizes and different mass ratios on the flow behavior of binary mixtures. Under the same mass ratio, the smaller the particle size of ceramic balls were, the greater the effect to promote the motion of biomass particles. The fluid-like motion changed more obvious with the increase of mass ratio and biomass particles.

Green catalyst for clean fuel production via hydrodeoxygenation.

The development of new fuel sources to replace nonrenewable fossil fuels has received substantial attention due to the ongoing demand for fossil fuels. Biomass and raw waste materials are crucial sources to produce suitable alternative fuels instead of nonrenewable fuels and offer a greener approach. Therefore, improving the fuel properties of biooils produced from the thermochemical conversion of biomass and raw waste materials is critical as it is used as an alternative to nonrenewable fuel. Developing an economical and eco-friendly method to produce sustainable and renewable oil by improving biooil containing large amounts of phenolic compounds has become imperative. One of the most intriguing and promising technologies for refining biooil to produce renewable fuels of comparable quality to conventional fossil fuels is the hydrodeoxygenation (HDO)-based process for converting biooil to renewable fuels. This method is almost one of the best improving methods described in the literature. At this point, it is of great importance that the HDO process is carried out catalytically. Carbon materials are preferred for both designing catalysts for HDO and supporting metal nanoparticles by providing chemically inert surfaces and tunable functional groups, high surface area and active sites. The HDO of biomass and raw waste materials has significantly advanced thanks to carbon-based catalysts. In this review, the effect of the surface character and catalytic ability of the carbon support, especially prepared by the green synthesis technique, on the HDO reaction during biooil improvement is discussed. Moreover, HDO reaction parameters and recent studies have been investigated in depth. Thus, green carbon catalysts' role in clean fuel production via the HDO process has been clarified.