Biomass Sugars for Non-Fuel Applications: Volume 44 (Green Chemistry Series) - Hardcover

Hardcover

ISBN 10: 178262113X ISBN 13: 9781782621133

Publisher: Royal Society of Chemistry, 2015

Synopsis

Providing an overview of sugar-based technologies, this book is a valuable resource for chemists working to develop greener synthetic routes to chemicals and pharmaceuticals.

About this title

About the Authors

Dmitry Murzin is Chair of Chemical Technology at Åbo Akademi University. He serves on the editorial boards of several journals in the catalysis and chemical engineering fields, and is an elected member of the Societas Scientiarum Fennica and Svenska Tekniska Vetenskapsakademien i Finland science academies.

Olga Simakova works at Georgia Institute of Technology, where her research focus is on the development of biomass conversion into biofuels via low-temperature catalytic pyrolysis.

From the Back Cover

Biomass-derived sugars provide a rich, renewable feedstock for a diverse range of chemicals, making them a promising and feasible source for the sustainable manufacture of a variety of valuable products.

Exploring green sugar-based technologies beyond their applications in fuels, this book provides an overview of sugar-based technologies, describing their challenges and opportunities. It covers transformations of sugars into green chemicals in pharmaceuticals, biodegradable polymers and surfactants. A special chapter is dedicated to the conversion of biomass into sugars, which is a crucial step in the sustainable utilization of sugars. The book is a valuable resource for chemists and chemical engineers working to develop greener synthetic routes to chemicals and pharmaceuticals.

From the Inside Flap

Biomass-derived sugars provide a rich, renewable feedstock for a diverse range of chemicals, making them a promising and feasible source for the sustainable manufacture of a variety of valuable products.

Exploring green sugar-based technologies beyond their applications in fuels, this book provides an overview of sugar-based technologies, describing their challenges and opportunities. It covers transformations of sugars into green chemicals in pharmaceuticals, biodegradable polymers and surfactants. A special chapter is dedicated to the conversion of biomass into sugars, which is a crucial step in the sustainable utilization of sugars. The book is a valuable resource for chemists and chemical engineers working to develop greener synthetic routes to chemicals and pharmaceuticals.

Excerpt. © Reprinted by permission. All rights reserved.

Biomass Sugars for Non-Fuel Applications

By Dmitry Murzin, Olga Simakova

The Royal Society of Chemistry

Copyright © 2016 The Royal Society of Chemistry
All rights reserved.

ISBN: 978-1-78262-113-3

Contents

Chapter 1 Conversion of Biomass into Sugars Prasenjit Bhaumik and Paresh Laxmikant Dhepe, 1, 
Chapter 2 Aqueous-phase Reforming of Sugar Derivatives: Challenges and Opportunities T. M. C. Hoang, A. K. K. Vikla and K. Seshan, 54, 
Chapter 3 Catalytic Hydrogenation of Sugars Dmitry Yu Murzin, Angela Duque, Kalle Arve, Victor Sifontes, Atte Aho, Kari Eränen and Tapio Salmi, 89, 
Chapter 4 Advances in Sugar-based Polymers: Xylan and its Derivatives for Surface Modification of Pulp Fibres Beatriz Vega, Olga Grigoray, Jan Gustafsson and Pedro Fardim, 134, 
Chapter 5 Recent Advances in the Synthesis of Sugar-based Surfactants José Kovensky and Eric Grand, 159, 
Chapter 6 Oligosaccharides for Pharmaceutical Applications Jani Rahkila, Tiina Saloranta and Reko Leino, 205, 
Chapter 7 Non-fuel Applications of Sugars in Brazil Peter R. Seidl, Estevão Freire and Suzana Borschiver, 228, 

CHAPTER 1

Conversion of Biomass into Sugars

PRASENJIT BHAUMIK AND PARESH LAXMIKANT DHEPE

1.1 Introduction

In the current circumstances, fossil feedstocks (crude oil, coal and natural gas) are utilized for the synthesis of a range of chemicals and fuels. Yet, their sustainability is at stake due to finite reserves, sporadic prices, volatile geopolitical scenarios and unfavourable effects on the environment (global warming) because of the discharge of a major contributor to the greenhouse gas effect, carbon dioxide (CO2) into the atmosphere. During World Wars I and II, due to a shortage of crude oil, Germany and a few other countries started extensive research on the production of chemicals and fuels (particularly ethanol and diesel) from alternate sources such as coal and biomass. The world's first ethanol production plant (Skutskär sulfite ethanol plant), based on the sulfite process, was started in 1909 in Sweden. Although a total of 33 plants were started using the same concept in Sweden, since 1983, just one plant has remained operational. After the development of efficient ways throughout the 20th century to explore, extract and process crude oil, research on biomass was decreased. But, following the recent crisis in oil production and for geo-political reasons, there has been a renewed interest in looking for alternative sources for the synthesis of chemicals and fuels. Though, for a long time, Brazil has successfully shown that due to the highest world production of sugarcane (Brazil: 3.3 x 108- 7.7 x 108 ton per year in 2000–2013, World: 1.3 x 109-1.9 x 109 ton per year in 2000-2013), it can produce bio-ethanol from bagasse (sugarcane waste after extracting sugar juice) in large quantities for public distribution to run vehicles. Conversely, in the rest of the world, after numerous deliberations and considering history, recently, it has been suggested that the only alternative and sustainable resource, biomass should be leveraged for the synthesis of chemicals and fuels by developing environmentally benign pathways. Since biomass is renewable, carbon neutral, abundant, locally accessible in most countries and has a lower impact on the environment, it becomes a natural choice as an alternate resource. In recent times, several countries and industries have disclosed their interests in developing methods for the conversion of biomass into known and new chemicals and fuels. Biomass is a non-fossil and is made up of complex molecules present in plants and animals. It is considered as a rich source of organic products, which have a characteristic chemical composition of C, H, O, N. However, until now, much of the work has reported on the conversion of plant-derived biomass into chemicals. Naturally, plant biomass is produced during the photosynthesis pathway using water, carbon dioxide and sunlight and is classified into two categories, namely edible and non-edible, solely based on human consumption ability. For example wheat, rice, corn, potato etc. are made up of a polysaccharide, starch and are considered as edible biomass or a first generation raw material (for the synthesis of fuels and chemicals). Starch is composed of a mixture of linear polysaccharide, amylose (homopolymer of D-glucose linked via a α-1,4 glycosidic bond) and branched polysaccharide, amylopectin (homopolymer of D-glucose linked via a linear α-1,4 glycosidic bond and branched α-1,6 glycosidic bond). Non-edible biomass, for example crop waste or wood, is called lignocellulosic biomass or lignocelluloses and is considered as a second generation raw material. Lignocelluloses have a composition of ca. 45% cellulose (homopolymer or homopolysaccharide of D-glucose linked via a β-1,4 glycosidic bond), ca. 25% hemicellulose (heteropolymer or heteropolysaccharide of several C5 and C6 sugars linked via various bonds), ca. 20% lignin (amorphous 3D network polymer of several aromatic monomers), some macro and micro nutrients (nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, manganese, copper, boron, zinc, chloride and molybdenum) and extractives (fats, fatty acids, resins, tannins, volatile oils, proteins etc.). Typically, saccharides or carbohydrates (hydrates of carbon) have a molecular formula of Cm(H2O)n, where m and n are almost same. For instance, a simple monosaccharide, glucose has a molecular formula of C6H12O6 while deoxyribose has a molecular formula of C5H10O4. This makes saccharides rich in oxygen content with an O/C ratio of ca. 1 and a H/C ratio of 2. Usually, during the formation of disaccharides or polysaccharides for example cellobiose (glucose dimer or disaccharide) with a molecular weight of 342 and cellulose (glucose polysaccharide) with per unit of glucose molecular weight of 162, loss of one mole of water (H2O) with a molecular formula of 18 per two moles of monosaccharides is essential. Hence, the O/C ratio in cellulose and hemicellulose (lignocelluloses) has a slightly lower value (ca. 0.8). Nevertheless, for a chemical to be used as a fuel or fuel additive, its O/C ratio should be low (biodiesel: ca. 0.1, ethanol: 0.5). Consequently, conversions of saccharides into fuels or fuel additive necessitates extra processing for the reduction in O/C ratio. At the same time, conversions of saccharides into chemicals (sugars and its derivatives) for non-fuel applications exempt the extra process of decreasing the O/C ratio. Hence, it is apparent that lignocelluloses should be used for chemical production. Moreover, economic analysis suggests that while lignocelluloses are obtainable at a price of $50 per ton, glucose has a market price of $450–650 per ton and xylose has a market price of $1000–2500 per ton. Further conversion of these monosaccharides (sugars) into various chemicals such as 5-hydroxymethylfurfural (HMF) ($300 000–350 000 per ton), furfural ($2500–3000 per ton), sorbitol ($500–700 per ton) and xylitol ($1000–3000 per ton) adds value to these sugars. Hence, it is understandable that suitable transformations of starch, cellulose and hemicellulose to various sugars (C6 and C5) via hydrolysis of glycosidic bonds present in polysaccharides are economical. Nevertheless, use of a first generation biomass (polysaccharide), starch for obtaining sugars as platform chemicals to produce a variety of other essential chemicals is a debatable issue since it is principally used as a food. Hence, use of a second generation biomass, lignocelluloses (non-edible biomass) — with a high energy content (ca. 2 1010 J per ton of dry biomass)10 is desirable for the synthesis of sugars. Additionally, huge worldwide availability (1.8 x 1012 tones) of plant-derived lignocelluloses including crop (agricultural) wastes and forest residues (90–95% with respect to total plant biomass production)8 might permit those to be used as a feedstock for better rural economy. On the other hand, in an ideal scenario, it can be considered that from non-edible feedstock, one can produce edible products (sugars). The conversion of di/ polysaccharides into chemicals can be done by either thermal (combustion, pyrolysis, gasification, supercritical water), thermo-chemical (acid, alkali) or biological (enzyme) methods. Under thermal conditions, substrates are heated at high temperatures (pyrolysis: >350 [°]C; gasification: >550 [°];C, supercritical water: ~300–400 [°]C) essentially without a catalyst (however, in a few cases such as gasification and treatment in supercritical water, catalysts are added to drive the reaction in a particular direction) to yield sugars, tar, char, gases etc. In most of these studies, gases (CO, CO2, H2, CH4etc.) are formed as the main products with a minor quantity of sugars formed (<20–30%). On the contrary, under thermo-chemical conditions at lower temperatures (<250 [°]C), catalysts are used to obtain sugars in higher quantities by subjecting substrates to hydrolysis. Considering this, in this chapter, discussions are focused on the conversion of di/ polysaccharides into sugars by hydrolysis reactions. In the conversion of lignocelluloses to chemicals, multiple steps are involved and these are depicted in Figure 1.1.

1.1.1 Potential Source of Sugars

Monosaccharides, or else we call them sugars, are named in two ways: (1) a monosaccharide containing an aldehyde group is called aldose and (2) a monosaccharide containing a ketone group is called ketose. In total, eight C6 aldo-sugars (glucose, mannose, galactose, allose, altrose, gulose, idose and talose) and four C5 aldo-sugars (xylose, arabinose, ribose and lyxose) are structurally possible. Besides these aldo-sugars, two more keto-sugars viz. fructose and xylulose are also well-known in nature. But, among them, idose and talose are not found in nature. Moreover, the presence of allose, altrose, gulose, ribose and lyxose is very rare in nature and hence discussions on those are not made here. The rest of the sugars are generally present in fruits, edible plants, living bodies, bacteria, proteins etc.

In Figure 1.2, likely sources of main C6 sugars (glucose, fructose, mannose, galactose) and C5 sugars (xylose, arabinose, xylulose) are illustrated. In general, these monosaccharides (sugars) can be obtained by the hydrolysis (addition of one mole of water per 2 moles of sugars) of their respective disaccharides [maltose: α-1,4-D-glucose disaccharide (found in potatoes, cereal, beverages etc.), cellobiose: β-1,4-D-glucose disaccharide, sucrose: disaccharide of α-D-glucose and β-D-fructose linked via a 1,2 glycoside bond (found in sugarcane, beet, grains etc.), xylobiose: β-1,4-D-xylose disaccharide etc.]. Further, several polysaccharides such as starch (α-1,4-D-glucose polysaccharide), cellulose (β-1,4-D-glucose polysaccharide), inulin (fructose polysaccharide), hemicellulose (polysaccharide of several C5 and C6 sugars) etc. derived from edible and non-edible parts of plant biomass can yield sugars on hydrolysis. Moreover, lignocelluloses are made up of ca. 75% of polysaccharides (cellulose, hemicellulose, starch and saccharose) and hence, it will be beneficial to use plant biomass (lignocelluloses) directly for the synthesis of various sugars. Since cellulose is present as a major component (ca. 45%) in lignocelluloses, its conversion into chemicals (mainly sugars) is considered as foremost in the bio-refinery concept. In recent times, municipal solid wastes (kitchen waste containing cellulose) have also been increasing and their effective utilization to generate chemicals and fuels may prove to be vital in curbing the problems of landfill and incineration, which gives rise to pollution by liberating hazardous chemicals and gases.

1.1.2 Applications of Sugars

Sugars have a variety of applications in fine chemicals, pharmaceuticals, agriculture, cosmetics etc. In most cases, sugars are used as an energy source (glucose), low-calorie sweetener (xylose) and for the synthesis of many industrially important chemicals such as furans (5-hydroxymethylfurufral and furfural; precursors for fuel, resin, plastic, nylon, polyester, fine chemical etc.), sugar alcohols (sorbitol, mannitol, xylitol, arabitol; used as low-calorie sweetener, adhesive, cosmetics, energy source etc.), sugar acids (gluconic acid, xylonic acid, arabinonic acid; used as chelating agent, cement retardant, cosmetics, medicine etc.), acids (succinic acid, itanoic acid, formic acid, glycolic acid; used in the food industry and polymer industry), alcohols (ethanol, butanol; used as fuels, solvents etc.) and alkyl ethers of sugars (alkyl glucoside, alkyl xyloside; used as biomass-derived surfactant etc.) Because of these extremely significant applications of sugars, it is worth synthesizing sugars from biomass-derived resources.

1.2 Biomass Pre-treatment

As suggested in Section 1.1.1, the most favourable way to synthesize sugars is the utilization of lignocellulosic (non-edible) biomass directly as a raw material which consists of polysaccharides (ca. 45% cellulose and ca. 25% hemicelluloses) in large quantities. But, in reality, due to very intricate hydrogen bonding such as intra-, inter-molecular and inter-sheet in cellulose (Figure 1.3), the existence of lignin (aromatic polymer) in lignocelluloses, and multiple bonding between polysaccharides and lignin, it becomes complicated to process lignocelluloses directly into sugars. During the conversion of the polysaccharide part (cellulose and hemicellulose) of lignocelluloses into sugars, lignin remains unconverted because it usually requires high processing temperatures (>250 °C) compared to polysaccharides (<230 °C). And if conversions of lignin are also tried simultaneously then degradation reactions of sugars become predominant. In most cases, unconverted lignin is also capable of poisoning the catalytically active sites. As discussed earlier, due to the occurrence of multiple H-bonding in cellulose, its structure becomes very rigid and crystalline and thus becomes difficult to degrade. A representative XRD pattern for commercially available microcrystalline cellulose is presented in Figure 1.4. The pattern shows peaks due to the amorphous (2θ = 15.81) and crystalline phases (2θ = 22.51, 34.7[°]) of cellulose. Additionally, due to the very strong H-bonding in cellulose, it remains insoluble in many common solvents but is soluble in ionic liquids (ILs), concentrated aqueous ZnCl2 solution and ammoniacal Cu(OH)2 solution. Cellulose also possesses a very high degree of polymerization (DP), for example in wood pulp, it ranges from 300 to 1700 and in cotton and plant fibres, it ranges from 800 to 10 000. Because of these properties of cellulose, its hydrolysis becomes difficult. Furthermore, the presence of lignin (covering polysaccharides), which has the role of protecting the polysaccharides from any chemical or biological attacks, hinders their catalytic conversions. Hence, it becomes indispensable to pretreat the lignocelluloses before hydrolysis for the removal of lignin and to decrease the crystallinity of cellulose. Other significant aspects in pretreatment are to avoid the degradation or loss of saccharides and make the overall process economic and environmental friendly. During some of the pre-treatments, the DP of cellulose decreases, which may increase the solubility of cellulose (fractions) in water for efficient hydrolysis.

The available biomass pre-treatment methods are classified roughly into three categories namely: (1) physical (milling, grinding, radiation, ultrasound), (2) physico–chemical (steam explosion, ammonia fiber explosion, carbon dioxide explosion) and (3) chemical (ozonolysis, alkaline hydrolysis, oxidative delignification, organic solvent extraction, acid hydrolysis, enzyme treatment, and ionic liquid treatment).

1.2.1 Physical Treatment

The main purpose of the physical pre-treatment of lignocellulose is to decrease its particle size and cellulose crystallinity. Use of milling and grinding methods can decrease the size of various biomass to 0.2–2mm from 10–30mm. The size reduction of lignocellulose is directly related to the energy consumption and time required for pre-treatment processing. Several reports on the ball milling method show a reduction in size (determined by particle size analyser), crystallinity (determined by XRD, NMR studies) and degree of polymerization (DP; determined by anion-exchanged chromatography) in cellulose and hence, increases in its hydrolysis rate. During ball milling, an increase in temperature is seen, which has an effect on decrystallization and for this reason, it becomes important to control the temperatures for reproducible results. Recently, an ultrasound technique has been used to decrease cellulose crystallinity within a short time in the presence of water. It is shown that Avicel cellulose (particle size = 38 µ m) can be transformed into 0.1–0.6 µ m cellulose with a 12.1% decrease in crystallinity index (without changes in its structure) at 80 °C after subjecting it to ultrasound treatment (optimum amplitude = 40%) for 3 h. It is assumed that when cellulose is exposed to ultrasound, which has a higher energy than the H-bonding energy of cellulose (21 kJ mol-1), it breaks the H-bonding in cellulose to form lower crystalline cellulose. Microwave irradiation of lignocellulosic biomass causes localized heating of lignocellulose leading to disruption of the lignocellulose structure and since it is a harsh process, it leads to very high lignin removal from biomass. However, in terms of cost and generation of high temperature during treatment, the process is not efficient on a large scale. Additionally, treatment of cellulose with γ-rays leads to the reduction of DP and crystallinity in cellulose but this process also faces the drawback of high costs.

(Continues...)

Excerpted from Biomass Sugars for Non-Fuel Applications by Dmitry Murzin, Olga Simakova. Copyright © 2016 The Royal Society of Chemistry. Excerpted by permission of The Royal Society of Chemistry.
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Edition details

• Publisher: Royal Society of Chemistry
• Publication date: 2015
• Language: English
• ISBN 10: 178262113X
• ISBN 13: 9781782621133
• Binding: Hardcover
• Number of pages: 280
• Editor: Dmitry Murzin