Recent Development of Biomass Conversion using Ionic Liquid-based Processes

Chapter 18 - Ionic liquids and their beneficial contributions to enzyme-catalyzed reactions, catalytic biomass conversion and energy conversion and storage systems

Green house gas emissions, the depleting of non-renewable resources, and poor waste management have a detrimental environmental and socioeconomic impact. Consequantly, the development of alternative processes that alleviate these problems is imperative. Apart from being an energy source, biomass has the capability of providing solid, liquid and gaseous forms of energy carriers and chemicals that can be transformed into analogues of those originating from fossil fuels. This thesis provides some ways in which the aforementioned problems could be tackled with a focus on the development of novel catalytic conversion processes that transforming cellulose, sourced from plant biomass, into key platform chemicals. A general overview of biomass transformation technologies is provided in chapter 1. The conversion of various biomass derivatives into 5-hydroxymethylfurfural (HMF) has been identified as a key route as HMF serves as a precursor to numerous platform chemicals. We achieved significant improvements in downstream biomass processing pathways by performing an extensive design and detailed investigations into understanding the reaction mechanism and optimization of various catalytic systems. In particular, chapter 2 is dedicated to the design of a new ionic liquid that enhances the conversion of glucose into HMF, in combination with a CrCl2 pre-catalyst, affording HMF in a yield significantly superior to that obtained in other ionic liquids and allowing the process to operate under milder conditions to those required by other catalysts. In chapter 3 we describe the development of the transformation of more complex carbohydrates such as starch and cellulose, using novel ionic liquid mixtures. Here, we obtained high yields of HMF, whereas no product was observed when ionic liquids from the current state of the art were employed, demonstrating the efficacy of the new system. Although HMF is a key intermediate, its transformation into other value-added molecules is also important. A key derivative of HMF is 2,5-furandicarboxylic acid (FDCA), which is bio-based substitute of the petroleum-based monomer for the plastics industry. FDCA-derived polymers have outstanding properties that match or even excel the current market benchmark polymer, i.e. PET. In chapter 4 we present the development of a novel Pt-based catalyst for HMF oxidation, affording quantitative yields of FDCA, under mild conditions. In chapter 5 a new bimetallic rhodium-nickel catalyst for the hydrogenation of HMF is described. In water the catalyst is able to convert HMF into 3-hydroxymethylcyclopentanone (HCPN) in 90% yield whereas in organic solvents other products are obtained: e.g. 60% of 2,5-dimethylfuran (DMF) in 1,2-dimethoxyethane (DME)/formic acid (FA) mixture. These products have widespread uses as alternative fuels and have high commercial value for the market.

Biomass conversion processes such as pretreatment, liquefaction, and pyrolysis often produce complex mixtures of intermediates that are a substantial challenge to analyze rapidly and reliably. To characterize these streams more comprehensively and efficiently, new techniques are needed to track species through biomass deconstruction and conversion processes. Here, we present the application of an emerging analytical method, gradient elution moving boundary electrophoresis (GEMBE), to quantify a suite of acids in a complex, biomass-derived streams from alkaline pretreatment of corn stover. GEMBE offers distinct advantages over common chromatography-spectrometry analytical approaches in terms of analysis time, sample preparation requirements, and cost of equipment. As demonstrated here, GEMBE is able to track 17 distinct compounds (oxalate, formate, succinate, malate, acetate, glycolate, protocatechuate, 3-hydroxypropanoate, lactate, glycerate, 2-hydroxybutanoate, 4-hydroxybenzoate, vanillate, p-coumarate, ferulate, sinapate, and acetovanillone). The lower limit of detection was compound dependent and ranged between 0.9 and 3.5 umol/L. Results from GEMBE were similar to recent results from an orthogonal method based on GCxGC-TOF/MS. Altogether, GEMBE offers a rapid, robust approach to analyze complex biomass-derived samples, and given the ease and convenience of deployment, may offer an analytical solution for online tracking of multiple types of biomass streams.

There is not enough land for the current bioenergy production process because of its low annual yield per unit land. In the present paper, an integrated biomass production and conversion process for sustainable bioenergy is proposed and analyzed. The wastes from the biomass conversion process, including waste water, gas and solid are treated or utilized by the biomass production process in the integrated process. Analysis of the integrated process including the production of water hyacinth and digestion for methane in a tropical area demonstrates several major advantages of the integrated process. (1) The net annual yield of methane per unit land can reach 29.0 and 55.6 km3/h for the present and future (2040) respectively, which are mainly due to the high yield of water hyacinth, high biomethane yield and low energy input. The land demand for the proposed process accounts for about 1% of the world’s land to meet the current global automobile fuels or electricity consumption; (2) A closed cycle of nutrients provides the fertilizer for biomass production and waste treatment, and thus reduces the energy input; (3) The proposed process can be applied in agriculturally marginal land, which will not compete with food production. Therefore, it may be a good alternative energy technology for the future.

Biomass has emerged as an abundant and relatively low cost carbon resource alternative to fossil fuel resources in the sustainable production of specialty chemicals and biofuel. Levulinic acid is an attractive platform chemical. Upgrading of levulinic acid produces levulinate esters, which serve as a transportation fuel and fuel additive. The present review focuses on the development of sustainable conversion of biomass into levulinic acid and levulinate esters via ionic liquids dual solvent–catalysts. The synthesis routes of levulinic acid and levulinate esters and the corresponding ionic liquids are introduced. The biomass pretreament, as well as the conversions of lignocellulosic biomass and their derivatives into levulinic acid and levulinate esters, are detailed in relation to the catalytic role, properties, and performance of acidic ionic liquids. Finally, the operating conditions affecting the ionic liquids catalytic conversions are discussed as part of a comprehensive review of this topic.

Chapter 1 - Conversion of biomass to chemicals using ionic liquids

Process Simulation and Economic Analysis of Producing Liquid Transportation Fuels from Biomass

This book chapter presents a comprehensive overview of the techno-economic analysis of various thermochemical biomass conversion technologies for the production of fuels, chemicals and electricity. In the first part of the chapter, a brief introduction on the importance of alternative energy sources and the need for the techno-economic analysis for thermochemical conversion processes are discussed. In the next part, various thermochemical routes for biomass conversion processes are described. The reactor configurations, operating parameters and product composition for each of these processes are also discussed. The third section of the chapter focuses on the techno-economic analysis methodology and different steps involved in carrying out the feasibility of biomass conversion processes. Different process modelling tools and cost estimation methods are also discussed in this section. While in the fourth section, different techno-economic studies carried out by various researchers for the production of fuels, chemicals and electricity through thermochemical conversion routes are discussed in terms of process description, and the results are reported. In the final section, two case studies are discussed in details for techno-economic analysis. One case study is of fast pyrolysis for transportation fuel production, and the second one is for dimethyl ether (DME) production through gasification of biomass. This chapter will be helpful for understanding different techno-economic studies available and comparison of different thermochemical conversion routes to get the desired end product at the minimum cost.

Ionic liquids (ILs) can act as high-performance solvents for cellulose in biomass conversion processes. However, the increase in viscosity that occurs upon dissolution of the cellulose in ILs can cause problems. To overcome this problem, ILs can be mixed with an organic solvent. This study investigates the thermal risk of the cellulose dissolution process using mixed solvents, ILs, and organic solvents. Sealed-cell differential scanning calorimetry (SC-DSC) was conducted on mixtures of 1-butyl-3-methylimidazolium acetate (BmimAc) and three aprotic polar solvents [dimethyl sulfoxide (DMSO), dimethyl acetamide (DMAc), and N,N-dimethylformamide (DMF)] to investigate thermal hazards. In addition, for samples exhibiting exothermal behavior greater than 100 J g−1, a prediction of runaway reaction behavior was obtained using kinetic analysis. Results revealed that BmimAc/DMSO could undergo a violent exothermic reaction, with a risk of a runaway reaction depending on the process temperature.

Mixtures of water and organic cosolvents (mixed solvent systems) play an important role in mediating acid-catalyzed biomass conversion reactions. A minimum amount of water is typically required to dissolve biomass-derived materials, while adding an organic cosolvent can enhance the rates and selectivities of the desirable, catalytic reaction steps. Understanding the molecular-level bases underlying these solvent effects would provide a powerful measure of control over the reaction environment for biomass conversion processes, whereby the rates of desired reaction steps could be preferentially enhanced over the undesirable ones by modulating the composition of the solvent system. However, a quantitative basis to anticipate these solvent effects is currently lacking, and optimizing the composition of the liquid phase for new biomass conversion reactions typically requires laborious screening of the continuous space of possible mixed solvent systems. Herein, we summarize our efforts to estimate solvent effects on the rates and selectivities of liquid-phase, acid-catalyzed biomass conversions reactions using experiments, classical molecular dynamics simulations, and machine learning tools. We then synthesize these insights into a workflow that allows for the rational design of mixed solvent systems for acid-catalyzed biomass conversion processes using computationally efficient methods and minimal experiments. We demonstrate this design framework by analyzing two case studies: the acid-catalyzed dehydration of cyclohexanol to cyclohexene, and the partial dehydration of fructose to 5-hydroxymethylfurfural.

In the biochemical conversion of lignocellulosic biomass to biofuels, the process of pretreatment is currently one of the most difficult and expensive operations. The use of ionic liquids (ILs) in biomass pretreatment has received considerable attention recently because of their effectiveness at decreasing biomass recalcitrance to subsequent enzymatic hydrolysis. In addition, ILs have the potential for decreasing the need for corrosive or toxic chemicals and associated waste streams that can be generated by other pretreatment methods that utilize acids and/or bases. In this article, we address two significant challenges to the realization of a practical IL pretreatment process. First, we describe a mixture containing specific proportions of a ketone and an alcohol that precipitates cellulose and lignocellulosic biomass from solutions of the IL 1-ethyl-3-methylimidazolium acetate without the formation of intermediate gel phases. Second, an IL recovery process is described that removes lignin and most residual IL solutes and that minimizes energy and solvent use. These two techniques are demonstrated by the pretreatment of 100 g of corn stover with the recovery of 89% of the initial IL and separate corn stover fractions rich in glucans, xylans, lignin, and non-polar substances. These results highlight one potential approach towards the realization of a scalable ionic liquid pretreatment process technology that enables ionic liquid recovery and reuse.

Ionic liquids (ILs) are salts consisting of organic cations and inorganic/organic anions having melting transitions lower than 100°C. They hold promise as engineered materials in a variety of modern fields. They are used as green solvents or catalysts for chemical reactions, biocatalysts, biopolymers processing, active pharmaceutical ingradients in medicine, even as electrolytes for batteries. For batteries applications, ionic liquids must have high ionic conductivity, but most of the ionic liquids (monocationic) have low conductivities. To address this limitation, we describe in this chapter dicationic ionic liquids based on extended viologens. The colossal conductivities, σdc ~ 10−1.5·S cm1 of new diatonic ionic liquids in the same range of benchmark materials/electrolytes applied in fuel cells and batteries is reported. The relatively new class of ionic liquids consist of extended viologen bistriflimides containing oligoethyleneoxy groups were prepared via Zincke reaction under mild conditions and are excellent candidates as components in devices for energy conversion and storage applications. The synthesis and ionic conductivities of other ionic liquids and dicationic organic salts will be contrasted with dicationic ionic liquids in this chapter.

Lignocellulosic biomass has gained increasing recognition in the past decades for the production of value-added products (VAPs). Biomass feedstocks obtained from various sources, their composition, and pretreatment techniques employed for delignification into bioenergy production are discussed. The conversion processes of biomass into VAPs involve various methods. Notable among them are biochemical conversions; namely, anaerobic digestion and ethanol fermentation, and thermo-chemical conversions; namely, pyrolysis and gasification which are considered in this chapter. Microalgae can adapt to changes in the environment, producing biomass that serves as a precursor for a variety of biomolecules, such as proteins, which find their application in pharmaceutical, cosmetic, and biofuel industries. Suitable strains of freshwater microalgae biomass contain high levels of lipid which can be harnessed for bioenergy production. Hence, the advancement in the conversion of biomass into VAPs could help scientists and environmentalists for sustainable use of biomass in future developments.

Ionic liquids have been recognised as interesting solvents applicable in efficient lignocellulosic biomass valorisation, especially in biomass fractionation into individual polymeric components or direct hydrolysis of some biomass fractions. Considering the chemical character of ionic liquids, two different approaches paved the way for the fractionation of biomass. The first strategy integrated a pre-treatment, hydrolysis and conversion of biomass through the employment of hydrogen-bond acidic 1-ethyl-3-methyimidazolim hydrogen sulphate ionic liquid. The second strategy relied on the use of a three-step fractionation process with hydrogen-bond basic 1-ethyl-3-methylimidazolium acetate to produce high purity cellulose, hemicellulose and lignin fractions. The proposed approaches were scrutinised for wheat straw and eucalyptus residues. These different biomasses enabled an understanding that enzymatic hydrolysis yields are dependent on the crystallinity of the pre-treated biomass. The use of acetate based ionic liquid allowed crystalline cellulose I to change to cellulose II and consequently enhanced the glucan to glucose yield to 93.1 ± 4.1 mol% and 82.9 ± 1.2 mol% for wheat straw and eucalyptus, respectively. However, for hydrogen sulphate ionic liquid, the same enzymatic hydrolysis yields were 61.6 ± 0.2 mol% for wheat straw and only 7.9 ± 0.3 mol% for eucalyptus residues. These results demonstrate the importance of both ionic liquid character and biomass type for efficient biomass processing.

5-513 3 4-O-5 3 3nds to 1-position 1-3 3 Technical lignin types and their availabilityThe variation in technical lignin structure is partly caused by the botanical origin of the polyphenol but equally important is the method of extraction (Lora et al. 2008; Lora and Glasser 2002).Common pulping processes used for the extraction of lignin from lignocellulosic raw materials for the production of paper are listed below.The worldwide availability of technical lignins is presented in Table 1.3. Kraft pulping processThe most common chemical pulping process of wood today is the sulfate or kraft pulping process, a process using sodium sulfide under alkaline conditions.The lignin is partly cleaved and thiol groups were introduced at the -position of the propane side chain (Figure 1.8) resulting in a solubilized lignin.Kraft pulp mills have evolved in large efficient integrated facilities in which the recovery of pulping chemicals and 19 19 lignin is recovered by an alternative recovery process by acid precipitation, maturation and filtration giving novel types of sulfur-free lignin (Abcherli and Doppenberg 1998; Abcherli and Doppenberg 2000; Lora and Glasser 2002). Organosolv pulping and/or fractionation processesThe use of organic solvents, e.g.ethanol, allows avoiding the formation of sulfated byproducts.Organosolv pulping or fractionation enables the production of high quality cellulose AND high quality lignin.The water insoluble organosolv lignins are more pure containing a higher percentage of lignin.The major organosolv processes are the following: Lignol process, based on the Alcell ethanol/water pulping process, ASAM, Alkaline Sulfite Anthraquinone Methanol pulping, Organocell, Methanol pulping followed by anthraquinone/NaOH pulping, Acetosolv, an acetic acid/HCl pulping, Milox, formic acid/hydrogen peroxide delignification, Avidel, formic/acetic acid pulping.These processes are not commercial yet, but have been demonstrated at pilot and demonstration scale.Organosolv pulping or fractionation of lignocellulosic biomass is nowadays one of the selected pretreatments to produce high quality cellulose for pulp and/or biofuel production together with a high purity lignin for materials and chemicals.Both the Canadian company Lignol (former Alcell process; Hallberg et al. 2010) and the French company CIMV (Avidel process; Delmas 2008) are using an organosolv fractionation technology (Table 1.3).In this thesis, high purity organosolv lignins obtained from ethanol/water fractionations of mixed hardwoods (Alcell tm lignin) and wheat straw are studied for the production of aromatic chemicals described in Chapter 5. Biomass pretreatment and conversion (biorefinery)Examples of these biomass pretreatment and conversion processes are strong or dilute acid pretreated lignocellulosic biomass followed by enzymatic hydrolysis of the carbohydrates.The resulting lignin fraction contains a considerable amount of residual carbohydrates (Vishtal and Kraslawski 2011).No Medium l) Gnansounou (2010) m) Zimbardi et al. (1999) 1) Impurities are generally residual carbohydrates, ash and proteins and largely depends on feedstock and process 2) Former technology of Repap.Technologies, Canada (Alcell tm ) However, in oxidising atmosphere the char yields are lower.Carbonisation and solidification with maximum surface area of the char is obtained at 350-400C (Sharma et al. 2004).Below 300C no significant lignin degradation occurs, but volatile products are released due to dehydration, dehydrogenation, deoxygenation and decarboxylation reactions resulting from the breaking of weaker bonds and condensation reactions (rfo et al. 1999).At higher temperatures rearrangements take place producing volatiles (syngas: CO and H 2 ) and reactive free radicals reactions occur when also stronger bonds are broken (Ferdous et al. 2002).Phenolic components are the main volatile products that are released during the pyrolysis stage between 250-400 along Hydrodeoxygenation (HDO)In the early 80's kraft lignin was converted in a two-step "Lignol" process including hydrocracking and hydrodealkylation over an catalyst bed in hydrogen into 20% phenol and 14% benzene (Huibers and Parkhurst 1982).This process was highly selective but Supercritical depolymerizationBiorefinery processes aimed at liquefaction of lignocellulosic biomass and the extraction of valuable components for fermentation or recovery of chemicals are currently studied extensively.Different fluids were used to solubilize biomass and lignin for conversion and extraction of valuable compounds.is the production of monomeric phenolic compounds and these depolymerized aromatic chemicals are soluble in CO 2 .By selection of a CO 2 based fluid separation of the residual lignin and the produced mono-and oligomeric aromatic compounds can be accomplished.In this novel process the aromatic products were separated from insoluble residual lignin fragments and char by adiabatic pressure release.