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Biomass is considered as a clean source of renewable energy, utilization of biomass may reduce the environmental pollutions. This paper presents a review of the chemistry and process of depolymerization of biomass; which results in production of oil and gaseous fuels from such important renewable energy source. Also, thermal hydro-cracking of ligni...
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... meaning wood. Lignin is the second most found substance in wood behind cellulose; roughly it is 30% by weight. Unlike cellulose, which is a linear polymer partially aggregated in crystalline configuration, lignin has a random, noncrystalline network structure. A simplified representation of lignin's complex nature in chemical terms is given in Fig. 1. The main physiological function of lignin is to provide rigidity and strength to the plant cell walls. Lignin is responsible for increasing the mechanical strength properties to such an extent that huge trees with height of even more than 100 meters can remain upright. Lignin is chemically separated from biomass by a process called ...
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Drilling directional and horizontal wellbores plays an important role in the exploitation of hydrocarbons. In the case of long operated and unconventional fields the importance of this type of drilling is fundamental. The horizontal and directional drilling technologies are also applicable in other fields. Directional and horizontal holes are among...
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... It is formed by extensively branched short chains of different forms of sugars. These short chains of various sugar molecules include pentoses, hexoses, and uronic acids (Akash 2015). ...
The production of biofuels from microbial sources has emerged as a promising solution to address the energy crisis and environmental concerns associated with fossil fuels. The present chapter offers a thorough overview of the most recent developments and persistent challenges in this sector. It focuses on the considerable advancements in using microorganisms, such as bacteria, yeasts, and microalgae, to produce biofuels. It explores the utilization of various feedstocks, including lignocellulosic biomass and waste materials, to generate biofuels like biodiesel, bioethanol, and biogas. The chapter also covers applications of genetic and metabolic engineering methods to improve microbial biofuel production, including raising yields and enhancing substrate usage efficiency. Despite these efforts, various obstacles stand in the way of the widespread use of microbial-based biofuel generation. Critical issues such as the availability and sustainability of feedstocks, high production costs, and effective downstream processing are also discussed in detail. It also explores the environmental implications of biofuel production and the need for developing sustainable and eco-friendly processes. Further, this chapter sheds light on the life cycle assessment approach and its assessment methods in the field of biofuel production. The national biofuel policy of India is critically analyzed in the context of the policies from different developed countries. It also emphasizes the importance of continued research and development to overcome challenges, optimize production processes, and establish microbial biofuels as a viable and sustainable alternative to conventional fuels.
... It is especially used for the cracking of heavy feeds such as vacuum gas oils (VGO) due to its robustness against contaminants [84]. Therefore, HC has also been investigated for the conversion of biomass to biofuels [85][86][87], or for the conversion of plastic waste to naphtha-like liquids [47,88,89]. To process the plastic waste, a prior low-temperature pyrolysis is performed to liquify the feed after which it is fed to the hydrocracker [32,90]. ...
... Hemicellulose is reported to have the highest capacity of water uptake compared with other lignocellulosic components such as cellulose and lignin. This might result from the large differences in the chemical structures of hemicellulose, cellulose, and lignin [75]. Another reason for the increased hydrophobicity is related to the loss of hydroxyl groups, which act as a water adsorption agent in the biomass during hydrothermal treatment. ...
This review article focuses on recent studies using hydrothermal carbonization (HTC) for producing hydrochar and its potential application as a solid fuel pellet. Due to the depletion of fossil fuels and increasing greenhouse gas (GHG) emissions, the need for carbon-neutral fuel sources has increased. Another environmental concern relates to the massive amount of industrial processing and municipal solid waste, which are often underutilized and end up in landfills to cause further environmental damage. HTC is an appealing approach to valorizing wet biomass into valuable bioproducts (e.g., hydrochar), with improved properties. In this review, the effects of the main HTC reaction parameters, including reaction temperature, residence time, and feedstock to water ratio on the properties and yield of hydrochar are described. Following this, the pelletizing of hydrochar to prepare fuel pellets is discussed by reviewing the influences of applied pressure, processing time, pellet aspect ratio, moisture content of the hydrochar, and the type and dosage of binder on the quality of the resulting fuel pellet. Overall, this review can provide research updates and useful insights regarding the preparation of biowaste-derived solid fuel pellets.
... It is especially used for the cracking of heavy feeds such as vacuum gas oils (VGO) due to its robustness against contaminants [84]. Therefore, HC has also been investigated for the conversion of biomass to biofuels [85][86][87], or for the conversion of plastic waste to naphtha-like liquids [47,88,89]. To process the plastic waste, a prior low-temperature pyrolysis is performed to liquify the feed after which it is fed to the hydrocracker [32,90]. ...
End-of-life tires are discarded on a daily basis but even at present limited action has been taken towards boosting their recyclability as most of the tires are either incinerated or landfilled/stockpiled. The complexity of tires has also been drastically increased, with little attention to designing them specifically for recycling. The retreading process is currently under intense development, and end-of-life tires have the ability to be retread up to several times. Furthermore, powdering (pulverization and grinding) the tires and separating steel and textile from this stream is a promising route that has found expanding applications. The particle size and surface area of the produced powder, purity, rubber degradation, and the cost of equipment and production are the determining factors. Assessing all these factors shows that sc-CO2 pulverization is the most promising method overall in this respect. In terms of process-ability, devulcanization has received a lot of attention from the tire recycling industry, and numerous physical, chemical, and microbial processes and combinations are being developed to be industrialized in the near future. Nevertheless none of these processes is currently at a high enough technological readiness level to be operated at large scale. Literature data shows that extrusion in combination with an ultrasonic horn or sc-CO2 using diphenyl disulfide has the most potential. In the dissolution extraction process, in addition to breaking sulfur bonds, solvent extraction devulcanizes and separates rubber from other tire components at low temperatures. The purity of the extracted products e.g., rubber, carbon black (CB) and minerals in this way is much higher than that of other recycling methods.
Since applications of mentioned recycled products (powder and devulcanized tire) are limited, tire pyrolysis has become extremely important. Process parameters and reactor design play a significant role in degradation mechanisms and pyrolysis products e.g., light olefins and dienes, naphthenes, mono-aromatics, tar, polar aromatics and coke. Catalytic pyrolysis with promoted zeolites leads to larger yields of valuable products at the expense of the formation of tar and so-called polar aromatics, i.e. N/S/O containing aromatics. In addition, upgrading processes, e.g., hydro-treating can reduce polar aromatics in the pyrolysis products by up to 90%. Furthermore, the demineralization of pyrolytic carbon black and activated carbon production are promising processes that result in increased tire recovery rates.
... It was observed that the addition of solvents reduced the industrial scalability López et al. (2015) of the side chains into various free radicals and hydrogenated compounds into phenolic and alcohol derivatives. Finally, the ether bonds of the methoxyl groups convert into monophenols (Akash 2015). Decomposition is the process of breaking large compounds into smaller components via three major steps, namely dehydration, decarboxylation, and deamination. ...
The fuels and chemicals produced from the fossil-derived petroleum are on the verge of completion. As a result, petro-refinery-based commodity prices are rising despite their increasing demand. Moreover, the greenhouse gas emissions from petro-based fuels are devastating to the environment. Thus, the concerns over the search for alternative, renewable and green sources of fuels and platform chemicals have been raised. Among the explored bio-based sources, the biorefinery potential of lignocellulosic and algal feedstocks has been found to be the most promising due to their sustainability and versatility of multi-product generation. This chapter reviews the biorefinery approaches in various thermochemical and biological conversion routes of lignocellulosic and algal feedstocks for co-producing biofuels and biochemicals that can be widely applied in the industrial sectors like energy, food, pharmaceuticals, cosmetics and textiles. From lignocellulosic biomass, the co-production technologies of chemicals and fuels via lignin and sugar (C5 and C6) platforms have been focused. On the other hand, the generation of bioactive components such as lipids, carbohydrates and proteins from algae along with co-production of biofuels and biochemicals is also discussed. The utilization of recycle streams like crude glycerol and spent biomass residues is emphasized in the algal biorefineries. Finally, the current industrial scenarios of both lignocellulosic and algal biorefineries are outlined.
... This study was carried out in the absence of catalyst. Khan et al. (2017), Akash (2015), and Zhou et al. (2011) have shown that hydrogenation was being done without a catalyst. Actually, during reaction, intermediates of biomass promote liquefaction process. ...
Co-liquefaction of Thar coal with waste plastic and waste oil was carried out to get high-quality fuel from waste. Four major variables, temperature, residence time, hydrogen pressure and coal: waste plastic ratio, oil: coal and oil: waste plastic ratios were investigated. According to results, maximum oil yield was obtained at 400°C temperature, 100psi pressure, 60 min residence time, and oil: coal: waste plastic ratios of 6:2:2. An FTIR result and 13 C NMR analysis have shown extracted oil contains almost 84% aliphatic compounds and 16% aromatic compounds. Among aliphatic, there is more %age of diesel fraction. Extracted residue can also be used as a fuel in cement industry and in power generation plants because it contains almost 83-84% carbon with less than 1% sulfur.
... Pyrolysis produces energy fuels with a high fuel-to-feed in ratio, making it the most efficient biomass conversion process [72]. Biomass has three main compositions: cellulose, hemicellulose, and lignin, some extracts of which are soluble in polar or nonpolar solvents [73]. The biomass pyrolysis process is divided into four stages: drying, preheating decomposition, solid decomposition, and combustion [74]. ...
Renewable energy plays a significant role in the world for obvious environmental and economic reasons with respect to the increasing energy crisis and fossil fuel environmental problems. Biomass energy, one of the most promising renewable energy technologies, has drawn increasing attention in recent years. However, biomass technologies still vary without an integrated framework. Considering the theory of a technological paradigm and implementing a literature analysis, biomass technological development was found to follow a three-stage technological paradigm, which can be divided into: BETP (biomass energy technological paradigm) competition, BETP diffusion, and BETP shift. Further, the literature review indicates that waste, like municipal solid waste (MSW), has the potential to be an important future trend in the world and waste-to-energy (WTE) is designed for sustainable waste management. Among WTE, anaerobic digestion has the potential to produce energy from waste sustainably, safely, and cost-effectively. The new BETP technological framework proposed in this paper may offer new research ideas and provide a significant reference for scholars.
... Furthermore, sterols, tannins, essential oils, resins, dyestuffs, lignans, proteins, waxes, and some alkaloids are found [5]. The objective of this paper is to present thermal depolymerization of lignin, which is an extension to a previously published work [6]. ...
... In a recent study biomass depolymerization was presented [6]. It was found that the thermal stability of briquetted biofuel was higher than the wood based on the activation energy levels, particularly for hemicellulose and cellulose. ...
Lignin can be considered as a clean source of renewable energy, which may be a substitute to fossil fuel and thus reduce some of the environmental pollution. This paper presents a review of the thermal process of depolymerization of lignin; which results in production of oil and gaseous fuels from such important renewable energy source. Also, thermal hydro-cracking of lignin enhances the liquefaction of other solid fossil fuels such as coal, by producing intermediates which then react further with coal producing lower molecular weight material, which is more desirable.
In this paper, the effect of various sodium hydroxide (NaOH) treatment parameters on the adsorption efficiency of rice husk for the removal of methylene blue (MB) from water is studied. Various NaOH-based adsorbents were prepared by treating rice husk with different concentrations of NaOH solution as well as by varying the treatment time and temperature. The adsorbents were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and N2 adsorption studies. FTIR and TGA studies indicated that NaOH treatment results in the degradation and removal of hemicellulose, lignin, and silica of rice husks. The MB adsorption studies were done by varying parameters such as pH, adsorbent dosage, contact time, and initial concentration. These studies indicated that increasing the concentration of NaOH solution as well as time and temperature during the treatment of rice husk makes the adsorption process faster and improves its adsorption efficiency. The pseudo-second-order model was found to give the best fit among various models applied to the experimental data. The second-order rate constant for adsorption by adsorbent prepared by treating rice husk with 1 N NaOH at 90℃ for 4 h was more than three times greater than bare rice husk. Among various isotherms such as Freundlich, Langmuir, Temkin, and Redlich-Peterson applied to equilibrium data, the last one was found to give the best fit, indicating the heterogeneous nature of adsorbents. The maximum monolayer adsorption capacity was found to be 123.39 mg.g−1 and 71.28 mg.g−1 for NaOH-treated and bare rice husk, respectively.
