Biomass Conversion Processes Research Articles

Advances in lignin valorization from a biorefinery concept

Lignin valorization for fuels and value-added products is essential to enhance the profitability and sustainability of biorefineries. Due to the complex and heterogeneous structure of lignin, technical barriers hinder the implementation of economic lignin utilization. Here, we summarize the major challenges facing lignin valorization processes. Different pretreatment methods, especially emerging combinatorial pretreatment approaches for isolating and tailoring lignin are introduced. To overcome the heterogeneity of lignin structure and improve lignin processability, advances in fractionation approaches including organosolv extraction, membrane technology, and gradient precipitation are analyzed and presented. Furthermore, progress in lignin valorization by thermochemical and biological conversion coupling with pretreatment and fractionation are systematically reviewed. Finally, we discuss advanced strategies and perspectives for future research involving biomass pretreatment, lignin fractionation and conversion processes.

A Review Pyrolysis: Different Agricultural Residues and Their Bio-Char Characteristics

Due to the large availability of biomass resources, India has great potential for the production of biochar. Different types of thermochemical even biological processes have been adopted to convert biomass into value‐added products. Among those processes, pyrolysis is more convenient since it has several advantages of storing, transportation, and flexibility in solicitation such as turbines, combustion appliances, boilers, engines, etc. Fig. 1 Overview of the pyrolytic product. Illustrates different types of the existing biomass conversion process with their respective output. The study was undertaken to investigate the properties of various agricultural residues. Until recently, the use of BC (biochar) in agriculture was mainly focused on the application of BC as a soil amendment. However, there are opportunities to investigate in this wide field of study, as there are plenty of potential relationships between various parameters, such as (but not limited to) BC(biochar) feedstock material, dose, and its characteristics, type of soil, plant species, and target elements/compounds of the treatment. Other related aspects that were investigated are BC‐enhanced composting processes and obtaining the BC via pyrolysis of agricultural waste.

Stochastic techno-economic evaluation model for biomass supply chain: A biomass gasification case study with supply chain uncertainties

Sustainable development has been a goal for many industries, which can be achieved via the substitution of non-renewable feedstocks with greener alternatives such as substituting coal with biomass for gasification process. The sustainably produced biomass-derived syngas has a lower carbon emission when utilized as a fuel. Although most studies have reported the possible impact of biomass quality on the feasibility of biomass conversion process, there is still little published works on the incorporation of biomass quality directly into developed mathematical evaluation model. Therefore, this paper aims to perform techno-economic feasibility evaluation on biomass gasification process, with the consideration of various supply chain uncertainties via Monte Carlo simulation (i.e., biomass supply, biomass quality, biomass pricing, transportation fuel price, and syngas sale price). This is achieved via integration of a generic correlation equation relating biomass quality to specific syngas yield into the Monte Carlo model. Upon consideration of the uncertainties, this study revealed that mesocarp fibre has a higher net present value (NPV) in the range of Malaysian Ringgit (MYR) 70 million to greater than MYR 120 million amongst the three types of palm-based biomass (empty fruit bunches (EFB), palm kernel shells (PKS), and mesocarp fibre). Additionally, environmental assessment performed deduced that mesocarp fibre is slightly more preferable in the impact category for HTPI and TTP with a probability of 98 % to achieve the equivalent emissions within the lower range of 0–0.2 kg 1,4-C6H4Cl2,eq whereas EFB and PKS has a probability of 18 % and 28 %, respectively.

KINETIC STUDY ON HYDROTHERMAL COMPOSITION OF GLUCOSE IN NAOH SOLUTION WITH ZNO AS CATALYST

<p>Hydrothermal liquifaction is a biomass conversion process, where the structure of the biomass is convert into liquid components under super critical conditions with a high temperature. In this study, glucose is used as biomass. The purpose of this study was to study the reaction kinetics and determine the hydrothermal decomposition of glucose in NaOH solution. This experiment used 10 grams of glucose and dissolve it in 80 mL of NaOH solution then put it in an autoclave. Experiments were carried out by varying the heating temperature carried out in an autoclave with a magnetic stirrer. After heating at various temperatures, the autoclave is immediately cooled down. The processed material is filtered to separate insoluble solids from the liquid phase. The solid residue that has been separated from the liquid phase is then dried in an oven at 105°C for 24 hours. The composition of the filtrate was analyzed using the GC-MS method and the glucose concentration was analyzed using the Lane Eynon method. Prior to GC-MS analysis, the filtrate was distilled at atmospheric pressure until a solid residue remained. The sample analyzed is the result of distillation with a temperature above 100°C to ensure that there is no water and residual glucose in the sample. The results of GC-MS analysis of product samples from the hydrothermal decomposition process had 3 peaks. The first peak shows the compound 1,3 Dipalmitin which has an area of 14.74%, the second peak shows the Olealdehyde compound which has an area of 32.35%, and the third peak shows the 1,2-Epoxyhexadecane compound which has an area of 52.91%. The kinetics results in hydrothermal decomposition of glucose in this experiment obtained a reaction order of 2 with an activation energy (Ea) of 15.91 KJ / mol and a pre-exponential factor of 66.12.</p>

Short review on heteropoly acid based catalyst for valorization of biomass waste into valueable chemicals

Depletion of fossil fuels resources has triggered more research on finding potential alternative sources that are more sustainable such as biomass waste. However, deconstruction of the complex biomass waste into desired products is too challenging and usually require a strong catalyst with a great hydrolysing property. Common acids such as sulphuric acid, hydrochloric acid and nitric acid were the most studies for biomass conversion. These liquid acids catalysts suffer low recovery and recyclability that can be overcome by a solid acid catalyst. Heteropoly acid (HPA) catalyst is the preferred choice to replace these common acid catalysts as it is known to have a strong Bronsted acid site with an oxidizing property that allows this catalyst to hydrolyse and oxidize in one-step reaction. Furthermore, heteropoly acid (HPA) catalyst can be modified into heterogenous type of catalyst by solidifying HPA to increase the surface area and recyclability. Future work of this research is necessary to improvise the previous method of the catalyst preparation and to suppress the by-products after the catalytic process. In this review, we summarize the use of HPA catalyst in the complex reaction process of biomass conversion to valuable chemical products.

Biomass-Based Chemical Looping Gasification: Overview and Recent Developments

Biomass has emerged as one of the most promising renewable energy sources that can replace fossil fuels. Many researchers have carried out intensive research work on biomass gasification to evaluate its performance and feasibility to produce high-quality syngas. However, the process remains the problem of tar formation and low efficiency. Recently, novel approaches were developed for biomass utilization. Chemical looping gasification is considered a suitable pathway to produce valuable products from biomass among biomass conversion processes. This review paper provides a significant body of knowledge on the recent developments of the biomass-based chemical looping gasification process. The effects of process parameters have been discussed to provide important insights into the development of novel technology based on chemical looping. The state-of-the-art experimental and simulation/modeling studies and their fundamental assumptions are described in detail. In conclusion, the review paper highlights current research trends, identifying research gaps and opportunities for future applications of biomass-based chemical looping gasification process. The study aims to assist in understanding biomass-based chemical looping gasification and its development through recent research.

Analysis of the EU Secondary Biomass Availability and Conversion Processes to Produce Advanced Biofuels: Use of Existing Databases for Assessing a Metric Evaluation for the 2025 Perspective

Nowadays in Europe, the production of advanced biofuels represents a very important objective, given the strong interest in increasing sustainability throughout the transport sector. Production and availability of advanced biofuels are cited as a relevant issue in the most important international actions, such as the Sustainable Development Goals in UN Agenda 2030, EU RED II, and EU Mission Innovation 4, to cite a few of them. However, an important aspect to be considered is the prediction of feedstocks availability to produce advanced biofuel. The first aim of this paper is to assess the availability of European agricultural residues, forestry residues, and biogenic wastes in 2025. The data were collected through a deep review on open FAOSTAT and EUROSTAT databases and then elaborated by the authors. The analysis focuses on the fraction of feedstocks that can be used for advanced biofuels production, i.e., incorporating specific information on sustainable management practices, competitive uses, and environmental risks to preserve soil quality. An autoregressive model is developed to predict future availability, while also considering corrections due to the current pandemic. The results suggest that several European countries could produce enough sustainable advanced feedstocks to meet the European binding target. In particular, France, Germany, and Romania will have high production of agricultural feedstocks; while Austria, Finland, and Sweden will be rich of forestry residues; finally, Italy, France, and United Kingdom will have the highest availability of wastes. To complete the picture, a proper metric is introduced, aiming at generating a technology ranking of the examined alternative fuels, in terms of several relevant parameters such as biomass availability, Technology Readiness Level (TRL), quality of the biofuel, and costs. This analysis allows us to compare advanced biofuels and first-generation biofuels, whose utilization can impact the food market, while also contributing to the increase in the indirect land use change (ILUC). Although the first-generation biofuels remain the most common choice, the renewable (or green) diesel, pyrolysis bio-oil, green jet fuel, and the second-generation bioethanol are promising for different applications in the transport sector. Hydrotreated Vegetable Oils (HVO), Hydroprocessed Esters and Fatty Acids (HEFA), Anaerobic Digestion (AD), and transesterification from vegetable oil represent the most widespread and mature technologies. Thus, it seems mandatory that the transport sector will rely more and more on such fuels in the future. For such reason, a specific support for advanced biomass collection, as well as specific programs for conversion technologies development, are strongly suggested.

EFFICIENT BIOMASS CONVERSION PROCESS TO SUSTAINABLE ENERGY

A greener approach to sustainable energy production is by processing and burning biomass. Readily abundant across the globe, biomass can be obtained largely from agricultural, domestic and industrial processes. The growing concern for an energy source that is environmentally friendly, socially acceptable, and economically feasible, prompts researchers to explore the conversion of everyday biomass wastes in the form of municipal solid waste (MSW) and agricultural wastes (such as poultry litters, wood pellets) to useful energy(i.e., heat or electricity). This research work studied the two broad biomass conversion processes- thermochemical and biochemical. A comparative study was performed using poultry litter as the biomass feedstock in both conversion processes. The obtained data was justified considering the environmental, economic and social impacts of the biomass-to-energy source. At an industrial scale, biochemical processes are capital intensive as pre-treatment and post-treatment of both feedstocks and products are required. In addition, more reaction time is required for product formation and high volume of secondary wastes (sludge) are generated during the process. On the other hand, burning of biomass waste has been largely considered as a better approach due to the fact that the CO2 generated during the process is being balanced by an equivalent amount that plants capture through photosynthesis while they are growing, thus making biomass a carbon-neutral energy source. However, raw biomass possesses low density (30–50 kg/m3) and high moisture content that limits its usage for thermochemical processes. Therefore, the inclusion of a pelletizing process which allows easier economic storage, transportation, and energy conversion characteristics, is considered as an efficient and sustainable approach to biomass-to-energy conversion

An Overview on the Conversion of Forest Biomass into Bioenergy

Biomass plays a crucial role in mitigating the concerns associated with increasing fossil fuel combustion. Among various types of biomass, forest biomass has attracted considerable attention given its abundance and variations. In this work, an overview is presented on different pathways available to convert forest biomass into bioenergy. Direct use of forest biomass could reduce carbon dioxide emissions associated with conventional energy production systems. However, there are certain drawbacks to the direct use of forest biomass, such as low energy conversion rate and soot emissions and residues. Also, lack of continuous access to biomass is a severe concern in the long-term sustainability of direct electricity generation by forest biomass. To solve this problem, co-combustion with coal, as well as pelletizing of biomass, are recommended. The co-combustion of forest biomass and coal could reduce carbon monoxide, nitrogen oxides, and sulfide emissions of the process. Forest biomass can also be converted into various liquid and gaseous biofuels through biochemical and thermochemical processes, which are reviewed and discussed herein. Despite the favorable features of forest biomass conversion processes to bioenergy, their long-term sustainability should be more extensively scrutinized by future studies using advanced sustainability assessment tools such as life cycle assessment, exergy, etc.

Modeling of cost optimized process integration of HTL fuel production

Hydrothermal liquefaction (HTL) is an advanced biomass conversion process for biocrude production from a broad variety of organic feedstock, including wet waste streams. The intermediate biocrudes can be further upgraded to liquid hydrocarbon fuels and thereby contribute to the mitigation of greenhouse gases from the transport sector. This work investigates an optimized sub-system integration of transportation fuel production via sub-critical HTL of primary sewage sludge. The plant design integrates HTL conversion, biocrude upgrading via hydrotreatment, and an energetic valorization of the residual aqueous phase from HTL conversion via catalytic hydrothermal gasification (cHTG). The option of on-site hydrogen production via reforming of cHTG gas is examined for the purpose of biocrude upgrading. The modeling results show that the hydrogen demand for hydrotreatment could be covered by the valorization of the HTL by-products. The thermal management of an integrated biofuel plant is optimized with respect to subsystem cost based on in-depth process modeling to quantify mass and energy flows and principles of pinch analysis to design a heat exchanger network. The cost optimized configuration results in an overall process energy efficiency of 40.5%. The results provide a basis for design choices for future HTL plants.

(IMCS Second Place Best Poster Award) In-Situ Analysis of Volatile Organic Compounds in Biogas Fermentation Processes Using a Metal Oxide Gas Sensor Array

(IMCS Second Place Best Poster Award) In-Situ Analysis of Volatile Organic Compounds in Biogas Fermentation Processes Using a Metal Oxide Gas Sensor Array

Thermogravimetry of the Steam Gasification of Calluna vulgaris: Kinetic Study

On account of the continuous decrease in oil reserves, as well as the promotion of sustainable policies, there is an increasing interest in biomass conversion processes, which imply the search for new raw materials as energy sources, like forestry and agricultural wastes. On the other hand, gasification seems to be a suitable thermal conversion process for this purpose. This work studied the thermogravimetry of the steam gasification of charcoal from heather (Calluna vulgaris) in order to determine the kinetics of the process under controlled reaction conditions. The variables studied were temperature (from 750 to 900 °C), steam partial pressure (from 0.26 to 0.82 atm), initial charcoal mass (from 50 to 106 mg), particle size (from 0.4 to 2.0 mm), N2 and steam volumetric flows (from 142 to 446 mL·min−1) and catalyst (K2CO3) concentration (from 0 to 10% w/w). The use of the shrinking core model and uniform conversion model allowed us to determine the kinetic parameters of the process. As a result, a positive influence of catalyst concentration was found up to 7.5% w/w. The kinetic study of the catalytic steam gasification showed activation energies of 99.5 and 114.8 kJ·mol−1 and order of reactions (for steam) of 1/2 and 2/3.

Insight into the recent advances of microwave pretreatment technologies for the conversion of lignocellulosic biomass into sustainable biofuel

The utilization of renewable lignocellulosic biomasses for bioenergy synthesis is believed to facilitate competitive commercialization and realize affordable clean energy sources in the future. Among the pathways for biomass pretreatment methods that enhance the efficiency of the whole biofuel production process, the combined microwave irradiation and physicochemical approach is found to provide many economic and environmental benefits. Several studies on microwave-based pretreatment technologies for biomass conversion have been conducted in recent years. Although some reviews are available, most did not comprehensively analyze microwave–physicochemical pretreatment techniques for biomass conversion. The study of these techniques is crucial for sustainable biofuel generation. Therefore, the biomass pretreatment process that combines the physicochemical method with microwave-assisted irradiation is reviewed in this paper. The effects of this pretreatment process on lignocellulosic structure and the ratio of achieved components were also discussed in detail. Pretreatment processes for biomass conversion were substantially affected by temperature, irradiation time, initial feedstock components, catalyst loading, and microwave power. Consequently, neoteric technologies utilizing high efficiency-based green and sustainable solutions should receive further focus. In addition, methodologies for quantifying and evaluating effects and relevant trade-offs should be develop to facilitate the take-off of the biofuel industry with clean and sustainable goals.

Value added products from urban organic wastes: a whole systems perspective

Organic waste, specifically food waste and sewage sludge, is a challenge for sustainable waste management systems. The United States Environmental Protection Agency estimated that 38 million tons of food waste went to landfill in 2014. In the United States, public wastewater treatment plants process approximately 14 million dry tons of sewage sludge per year. Hydrothermal carbonization (HTC) is proposed as a solution to the large streams of food waste and sewage sludge. HTC is significantly more energy efficient than the industry standard processes used today. Compared to other biomass conversion processes, HTC has the highest carbon efficiency while having the lowest greenhouse gas emissions rate. HTC is a thermochemical process that converts wet biomass to a coal-like product that can be used as a solid fuel source, for soil amendment, or as a base for advanced applications such as activated carbon. Villanova University, with SoMax BioEnergy, is researching HTC and activation techniques for upgrading sewage sludge and food waste to activated carbon. The focus of the study is to evaluate these wastes as feedstocks for HTC and the subsequent activation to determine if an activated carbon adsorbent can be produced that is comparable to commercially available activated carbon using a whole systems perspective. This is a novel look as it involves determining the impacts of the process from social, technical, environmental, economic, and political (STEEP) perspectives.

Molecular dynamics of dissolution of a 36-chain cellulose Iβ microfibril at different temperatures above the critical pressure of water

The cellulose dissolution is an essential pretreatment process for the chemical conversion of lignocellulosic biomass into biofuels. Here, the dissolution of a 36-chain Iβ cellulose model with a hexagonal cross-section (M36HCS) in water is analyzed by Molecular Dynamics (MD) with CHARMM36/TIP3P (C36/TIP3P) force field using gradual heating at 25 MPa. Our simulations showed that the dissolution of M36HCS starts to occur between 560 K and 600 K, which agrees with experimental observations. In our system, conditions near the critical point of water reveal that translational and rotational entropies decrease, while the low hydration level increases vibrational entropy. This investigation theoretically shows that C36/TIP3P adequately reproduces the dissolution of M36HCS even in high-pressure water as corroborated in reactors.

Approaches to Biomass Kinetic Modelling: Thermochemical Biomass Conversion Processes

Modeling of biomass pyrolysis kinetics is an essential step towards reactors design for energy production. Determination of the activation energy, frequency factor, and order of the reaction is necessary for the design procedure. Coats and Redfern's work using the TGA data to estimate these parameters was the cornerstone for modeling. There are two significant problems with biomass modeling, the first is the determination of the kinetic triplet (Activation energy, Frequency factor, and the order of reaction), and the second is the quantitative analysis of products distribution. Methods used in modeling are either One-step or Multistep methods. The one-step techniques allow the determination of kinetic triplet but fail to predict the product distribution, whereas multistep processes indicate the product's distribution but challenging to estimate the parameters. Kissinger, Coats, and Redfern, KAS, FWO, Friedman are one-step methods that have been used to estimate the kinetic parameters. In this work, after testing more than 500 data points accessed from different literature sources for coal, oil shale, solid materials, and biomass pyrolysis using one-step global method, it was found that the activation energy generated by KAS or FWO methods are related as in the following equations: 𝐸𝐾𝐴𝑆 = 0.9629 ∗ 𝐸𝐹𝑊𝑂 + 8.85, with R² =0.9945 or 𝐸𝐹𝑊𝑂 = 1.0328 ∗ 𝐸𝐾𝐴𝑆 − 8.0969 with R2= 0.9945. The multistep kinetic models employed the Distributed Activation Energy Model (DAEM) using Gaussian distribution, which suffers from symmetry, other distributions such as Weibull, and logistic has been used. These multistep kinetic models account for parallel/series and complex, primary and secondary biomass reactions by force-fitting the activation energy values. The frequency factor is assumed constant for the whole range of activation energy. Network models have been used to account for heat and mass transfer (diffusional effects), where the one-step and multistep could not account for these limitations. Three network models are available, the Bio-CPD (Chemical Percolation Devolatilization) model, Bio-FLASHCHAIN, and the Bio-FGDVC (Functional Group Depolymerization Vaporization Crosslinking models). These models tried to predict the product distributions of the biomass pyrolysis process

Density Functional Investigation of the Conversion of Furfural to Furfuryl Alcohol by Reaction with i-Propanol over UiO-66 Metal-Organic Framework.

Carbonyl C═O bond reduction via catalytic transfer hydrogenation (CTH) is one of the essential processes for biomass conversion to valuable chemicals and fuels. Here, we investigate the CTH of furfural to furfuryl alcohol with i-propanol on UiO-66 metal-organic frameworks using density functional theory calculations and linear scaling relations. Initially, the reaction over two defect sites presented on Zr-UiO-66, namely, dehydrated and hydrated sites, have been compared. The hydrated active site is favored over that on the dehydrated active site since the activation free energy of the rate-determining reaction step occurring on the hydrated active site is lower than that occurring on the dehydrated active site (14.9 vs 17.9 kcal/mol). The catalytic effect of exchanged tetravalent metals (Hf and Ti) on Zr-UiO-66 is also considered. We found that Hf-UiO-66 (13.5 kcal/mol) provides a lower activation energy than Zr-UiO-66 (14.9 kcal/mol) and Ti-UiO-66 (19.4 kcal/mol), which corresponds to it having a higher Lewis acidity. The organic linkers of UiO-66 MOFs play a role in stabilizing all of the species on potential energy surfaces. The linear scaling relationship also reveals the significant role of the UiO-66 active site in activating the carbonyl C═O of furfural, and strong relationships are observed between the activation free energy, the charge of the metal at the MOF active sites, and the complexation energies in reaction coordinates.

A Review of Bio-Oil Production through Microwave-Assisted Pyrolysis

The issue of sustainability is a growing concern and has led to many environmentally friendly chemical productions through a great intensification of the use of biomass conversion processes. Thermal conversion of biomass is one of the most attractive tools currently used, and pyrolytic treatments represent the most flexible approach to biomass conversion. In this scenario, microwave-assisted pyrolysis could be a solid choice for the production of multi-chemical mixtures known as bio-oils. Bio-oils could represent a promising new source of high-value species ranging from bioactive chemicals to green solvents. In this review, we have summarized the most recent developments regarding bio-oil production through microwave-induced pyrolytic degradation of biomasses.

Techno-economic evaluation and sensitivity analysis of a conceptual design for supercritical water gasification of soybean straw to produce hydrogen

This paper proposes a conceptual design for the catalytic supercritical water gasification of soybean straw. The design consists of four process units for pretreatment, gasification, separation, purification and combustion. The economic feasibility of hydrogen production was evaluated based on a comprehensive cash flow analysis. The economic analysis suggested a minimum selling price of U.S. $1.94/kg for hydrogen. The cost of hydrogen produced is relatively lower compared to that of other biomass conversion processes. Besides, the net rate of return (NRR) estimated was 37.1%. A positive NRR value indicates that the project is profitable from an economic perspective. Sensitivity analysis indicates that the minimum selling price of hydrogen is affected by the feedstock price, utility cost, tax rate and labor cost. Moreover, feedstock price and labor cost show the greatest effect. Other factors such as land cost, working capital and utility cost showed the least effect on the minimum selling price.

Nitrogen-doped char as a catalyst for wet oxidation of phenol-contaminated water

Catalytic wet oxidation (CWO) of aqueous effluents rich in organic compounds is a very promising technology for the treatment of liquid wastes from biomass conversion processes. CWO reactions occur through the formation of free radical species, produced in the presence of an oxidant, which act on organic contaminates in the effluent. Although the reaction is well known, there exists a lack of affordable catalysts to conduct this process at the lower temperatures and pressures in novel bioenergy processes. This study assessed the catalytic effect of nitrogen-doped chars as such an option. Phenol in aqueous solution was used as a model waste effluent. Treatment was conducted at moderate temperatures (190 to 260 °C), oxygen partial pressure of 1 MPa, and reaction times of 15, 30, and 45 min in stainless steel and glass-lined tube reactors. High pressure liquid chromatography (HPLC) analyses of the products quantified phenol and by-product concentrations used in the calculation of reaction activation energy. The char catalyst was studied by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) in order to gain insight into its structure and surface composition. The results indicate that nitrogen-doped char catalysts accelerate the oxidation of phenol by decreasing its reaction activation energy from 82.2 kJ/mol (non-catalyzed) to 40.4 kJ/mol (catalyzed). An analysis from first principles using density functional theory (DFT) was conducted to ascertain which N functional group has the most significant impact on free radical formation in the presence of oxygen. Among all the N functional groups studied, the dipyridinic functional groups showed the most promising characteristics to facilitate the formation of hydroxyl free radicals.