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Journal ArticleDOI: 10.1007/S10311-021-01208-9

Processes and separation technologies for the production of fuel-grade bioethanol: a review

04 Mar 2021-Environmental Chemistry Letters (Springer Science and Business Media LLC)-Vol. 19, Iss: 4, pp 1-18
Abstract: Bioethanol produced from biological resources is considered as an alternative, renewable, and sustainable energy source in the context of the circular economy. Moreover, bioethanol is a biofuel that has similar energy content to gasoline, but emits less toxic pollutants compared to fossil fuels. Yet bioethanol must be anhydrous to be mixed with regular gasoline and is then utilized as a vehicle fuel. Different techniques have been developed to obtain anhydrous ethanol. Here, we compare techniques for dehydration of bioethanol, including adsorption and distillation. We present the performance of the process, product recovery, and energy consumption of the pressure swing adsorption method, which is effective and widely used.

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Topics: Biofuel (56%), Gasoline (52%), Renewable energy (52%) ... show more

5 results found

Open accessJournal ArticleDOI: 10.1007/S10311-021-01273-0
Ahmed I. Osman1, Neha Mehta1, Ahmed M. Elgarahy2, Amer Al-Hinai3  +2 moreInstitutions (3)
Abstract: The global energy demand is projected to rise by almost 28% by 2040 compared to current levels. Biomass is a promising energy source for producing either solid or liquid fuels. Biofuels are alternatives to fossil fuels to reduce anthropogenic greenhouse gas emissions. Nonetheless, policy decisions for biofuels should be based on evidence that biofuels are produced in a sustainable manner. To this end, life cycle assessment (LCA) provides information on environmental impacts associated with biofuel production chains. Here, we review advances in biomass conversion to biofuels and their environmental impact by life cycle assessment. Processes are gasification, combustion, pyrolysis, enzymatic hydrolysis routes and fermentation. Thermochemical processes are classified into low temperature, below 300 °C, and high temperature, higher than 300 °C, i.e. gasification, combustion and pyrolysis. Pyrolysis is promising because it operates at a relatively lower temperature of up to 500 °C, compared to gasification, which operates at 800–1300 °C. We focus on 1) the drawbacks and advantages of the thermochemical and biochemical conversion routes of biomass into various fuels and the possibility of integrating these routes for better process efficiency; 2) methodological approaches and key findings from 40 LCA studies on biomass to biofuel conversion pathways published from 2019 to 2021; and 3) bibliometric trends and knowledge gaps in biomass conversion into biofuels using thermochemical and biochemical routes. The integration of hydrothermal and biochemical routes is promising for the circular economy.

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Topics: Biofuel (61%), Biomass (60%), Life-cycle assessment (53%) ... show more

8 Citations

Journal ArticleDOI: 10.1007/S10311-021-01284-X
Abstract: The applications of green chemistry and industrial bioprocessing are becoming more popular to address concerns of pollution, climate change, global warming, circular bioeconomy, sustainable development goals and energy security. Both biological and thermochemical routes can play vital roles in transforming waste lignocellulosic biomass to high-value bioproducts. Lignocellulosic biomass contains essential building blocks that could be tapped to generate biofuels, biochemicals and biomaterials to replace petroleum-derived fuels and chemicals. Besides containing extractives and ash, lignocellulosic feedstocks are made up of cellulose, hemicellulose and lignin typically in the ranges of 35–55 wt%, 20–40 wt% and 10–25 wt%, respectively. Catalytic thermochemical approaches are effective for biomass conversion with a significant yield of various platform chemicals, such as furfural, 5-hydroxymethylfurfural, levulinic acid and other furan or non-furan-based chemicals. These chemicals play a crucial part in the synthesis of different fuel-based materials, which can successfully replace petroleum-based chemicals or fuels. Lignocellulosic biomass and their derived monomeric sugars can be catalytically converted into various platform chemicals using different homogeneous and heterogeneous catalysts. In this review paper, we have highlighted some promising catalysts such as mineral acids, mesoporous silica materials, zeolites, metal–organic frameworks, metal oxides and ionic liquids used in biorefining to generate biochemicals. We have also reviewed a few pieces of notable literature presenting the catalytic conversion of cellulose, hemicellulose, cellobiose, glucose, fructose and xylose into various high-value chemicals.

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Topics: Lignocellulosic biomass (64%), Biorefining (60%), Biomass (58%) ... show more

4 Citations

Open accessJournal ArticleDOI: 10.3390/PR9061028
10 Jun 2021-
Abstract: Ethanol is considered as a renewable transport fuels and demand is expected to grow. In this work, trends related to bio-ethanol production are described using Thailand as an example. Developments on high-temperature fermentation and membrane technologies are also explained. This study focuses on the application of membranes in ethanol recovery after fermentation. A preliminary simulation was performed to compare different process configurations to concentrate 10 wt% ethanol to 99.5 wt% using membranes. In addition to the significant energy reduction achieved by replacing azeotropic distillation with membrane dehydration, employing ethanol-selective membranes can further reduce energy demand. Silicalite membrane is a type of membrane showing one of the highest ethanol-selective permeation performances reported today. A silicalite membrane was applied to separate a bio-ethanol solution produced via high-temperature fermentation followed by a single distillation. The influence of contaminants in the bio-ethanol on the membrane properties and required further developments are also discussed.

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Topics: Membrane (57%), Ethanol fuel (56%), Azeotropic distillation (56%) ... show more

Journal ArticleDOI: 10.1007/S40726-021-00202-7
15 Sep 2021-
Abstract: The depletion of fossil reserves and environmental challenges associated with fossil fuels are major drivers of the search for sustainable renewable energy sources. Bioethanol production from macroalgae is one of the promising alternatives to reduce use of fossil fuels and achieve energy security and ecological sustainability. The purpose of this review is to critically discuss the options to optimize the process parameters for steady production of bioethanol from macroalgae. A comprehensive literature review reveals that bioethanol production from macroalgae not only depends on the macroalgae type but also on the selection of pretreatment, hydrolysis, and fermentation options. Unlike the first- and second-generation feedstocks, macroalgae contains low concentrations of glucans. Thus high bioethanol concentration cannot be achieved by converting only glucans. Therefore, it is important to produce bioethanol from other carbohydrate components of macroalgae, such as alginate, sulphated polysaccharides, carrageenan, mannitol, and agar. The selection of the right hydrolysing agents (e.g., enzyme and/or acid) and steps to minimize formation of inhibitors during the process were found to be important factors affecting the efficiency of hydrolysis process. The hydrolysis enzymes currently used were developed for lignocellulosic and starch-based biomass, not for macroalgae, which is different in polysaccharide structure and composition. Also, the lack of appropriate fermenting microorganisms capable of converting heterogeneous monomeric sugars in macroalgae is a major factor limiting bioethanol yield during the fermentation process. This review systematically discusses the implications of selecting different macroalgae types. The optimization of process parameters of different bioethanol production steps such as pretreatments, hydrolysis, and fermentation is discussed. It can be concluded that high bioethanol yield can be achieved by considering macroalgae type and composition, selecting appropriate pretreatment, hydrolysis, and fermenting microbes, and with effective bioethanol purification.

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102 results found

Journal ArticleDOI: 10.1016/J.RSER.2009.10.003
Abstract: Sustainable economic and industrial growth requires safe, sustainable resources of energy. For the future re-arrangement of a sustainable economy to biological raw materials, completely new approaches in research and development, production, and economy are necessary. The ‘first-generation’ biofuels appear unsustainable because of the potential stress that their production places on food commodities. For organic chemicals and materials these needs to follow a biorefinery model under environmentally sustainable conditions. Where these operate at present, their product range is largely limited to simple materials (i.e. cellulose, ethanol, and biofuels). Second generation biorefineries need to build on the need for sustainable chemical products through modern and proven green chemical technologies such as bioprocessing including pyrolysis, Fisher Tropsch, and other catalytic processes in order to make more complex molecules and materials on which a future sustainable society will be based. This review focus on cost effective technologies and the processes to convert biomass into useful liquid biofuels and bioproducts, with particular focus on some biorefinery concepts based on different feedstocks aiming at the integral utilization of these feedstocks for the production of value added chemicals.

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Topics: Aviation biofuel (64%), Second-generation biofuels (59%), Bioproducts (56%) ... show more

2,473 Citations

Journal ArticleDOI: 10.1016/J.PECS.2012.03.002
Alya Limayem1, Steven C. Ricke1Institutions (1)
Abstract: During the most recent decades increased interest in fuel from biomass in the United States and worldwide has emerged each time petroleum derived gasoline registered well publicized spikes in price. The willingness of the U.S. government to face the issues of more heavily high-priced foreign oil and climate change has led to more investment on plant-derived sustainable biofuel sources. Biomass derived from corn has become one of the primary feedstocks for bioethanol production for the past several years in the U.S. However, the argument of whether to use food as biofuel has led to a search for alternative non-food sources. Consequently, industrial research efforts have become more focused on low-cost large-scale processes for lignocellulosic feedstocks originating mainly from agricultural and forest residues along with herbaceous materials and municipal wastes. Although cellulosic-derived biofuel is a promising technology, there are some obstacles that interfere with bioconversion processes reaching optimal performance associated with minimal capital investment. This review summarizes current approaches on lignocellulosic-derived biofuel bioconversion and provides an overview on the major steps involved in cellulosic-based bioethanol processes and potential issues challenging these operations. Possible solutions and recoveries that could improve bioprocessing are also addressed. This includes the development of genetically engineered strains and emerging pretreatment technologies that might be more efficient and economically feasible. Future prospects toward achieving better biofuel operational performance via systems approaches such as risk and life cycle assessment modeling are also discussed.

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Topics: Biomass (55%), Sustainable biofuel (53%), Biofuel (52%) ... show more

1,019 Citations

Journal ArticleDOI: 10.1016/J.RSER.2013.06.033
Abstract: Pretreatment technologies are aimed to increase enzyme accessibility to biomass and yields of fermentable sugars. In general, pretreatment methods fall into four different categories including physical, chemical, physico-chemical, and biological. This paper comprehensively reviews the lignocellulosic wastes to bioethanol process with a focus on pretreatment methods, their mechanisms, advantages and disadvantages as well as the combinations of different pretreatment technologies. Moreover, the new advances in plant “omics” and genetic engineering approaches to increase cellulose composition, reduce cellulose crystallinity, produce hydrolases and protein modules disrupting plant cell wall substrates, and modify lignin structure in plants have also been expansively presented.

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Topics: Lignocellulosic biomass (57%), Biomass (53%)

885 Citations

Journal ArticleDOI: 10.1016/J.SEPPUR.2007.12.011
Abstract: Biorefineries process bioresources such as agriculture or forest biomass to produce energy and a wide variety of precursor chemicals and bio-based materials, similar to the modern petroleum refineries. Industrial platform chemicals such as acetic acid, liquid fuels such as bioethanol and biodegradable plastics such as polyhydroxyalkanoates can be produced from wood and other lignocellulosic biomass. Biorefineries use a variety of separation methods often to produce high value co-products from the various feed streams. In this paper, a critical review of separation methods and technologies related to biorefining including pre-extraction of hemicellulose and other value-added chemicals, detoxification of fermentation hydrolyzates, and ethanol product separation and dehydration is presented. For future biorefineries, extractive distillation with ionic liquids and hyperbranched polymers, adsorption with molecular sieve and bio-based adsorbents, nanofiltration, extractive-fermentation, membrane pervaporation in bioreactors, and vacuum membrane distillation (VMD) hold significant potential and great promise for further investigation, development and application.

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Topics: Biorefining (60%), Lignocellulosic biomass (55%), Biorefinery (54%) ... show more

750 Citations

Journal ArticleDOI: 10.1016/J.RSER.2010.03.015
Abstract: Anhydrous ethanol is one of the biofuels produced today and it is a subset of renewable energy. It is considered to be an excellent alternative clean-burning fuel to gasoline. Anhydrous ethanol is commercially produced by either catalytic hydration of ethylene or fermentation of biomass. Any biological material that has sugar, starch or cellulose can be used as biomass for producing anhydrous ethanol. Since ethanol–water solution forms a minimum-boiling azeotrope of composition of 89.4 mol% ethanol and 10.6 mol% water at 78.2 °C and standard atmospheric pressure, the dilute ethanol–water solutions produced by fermentation process can be continuously rectified to give at best solutions containing 89.4 mol% ethanol at standard atmospheric pressure. Therefore, special process for removal of the remaining water is required for manufacture of anhydrous ethanol. Various processes for producing anhydrous ethanol have been used/suggested. These include: (i) chemical dehydration process, (ii) dehydration by vacuum distillation process, (iii) azeotropic distillation process, (iv) extractive distillation processes, (v) membrane processes, (vi) adsorption processes and (vii) diffusion distillation process. These processes of manufacturing anhydrous ethanol have been improved continuously due to the increasingly strict requirements for quantity and quality of this product. The literature available on these processes is reviewed. These processes are also compared on the basis of energy requirements.

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Topics: Azeotropic distillation (62%), Extractive distillation (59%), Vacuum distillation (58%) ... show more

237 Citations

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