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Achieving the goal of living in a sustainable and greener society, will need the chemical industry to move away from petroleum-based refineries to bio-refineries. This aim can be achieved by using biomass as the feedstock to produce platform chemicals. A platform chemical, 2,5-furandicarboxylic acid (FDCA) has gained much attention in recent years because of its chemical attributes as it can be used to produce green polymers such polyethylene 2,5-furandicarboxylate (PEF) that is an alternative to polyethylene terephthalate (PET) produced from fossil fuel. Typically, 5-(hydroxymethyl)furfural (HMF), an intermediate product of the acid dehydration of sugars, can be used as a precursor for the production of FDCA, and this transformation reaction has been extensively studied using both homogeneous and heterogeneous catalysts in different reaction media such as basic, neutral, and acidic media. In addition to the use of catalysts, conversion of HMF to FDCA occurs in the presence of oxidants such as air, O2, H2O2, and t-BuOOH. Among them, O2 has been the preferred oxidant due to its low cost and availability. However, due to the low stability of HMF and high processing cost to convert HMF to FDCA, researchers are studying the direct conversion of carbohydrates and biomass using both a single- and multi-phase approach for FDCA production. As there are issues arising from FDCA purification, much attention is now being paid to produce FDCA derivatives such as 2, 5-furandicarboxylic acid dimethyl ester (FDCDM) to circumvent these problems. Despite these technical barriers, what is pivotal to achieve in a cost-effective manner high yields of FDCA and derivatives, is the design of highly efficient, stable, and selective multi-functional catalysts. In this review, we summarize in detail the advances in the reaction chemistry, catalysts, and operating conditions for FDCA production from sugars and carbohydrates.

Quaternary ammonium-functionalized magnetic chitosan microspheres (QAMCM) were fabricated for the removal of high-molecular-weight invert sugar alkaline degradation products (HISADPs), the main class of colorants in beet juice. The equilibrium adsorption capacity of QAMCM for HISADP was 98.03 mg/g at 0.6 mg/mL QAMCM dosage, 333 K temperature, pH 7, and 60 mg/L initial HISADP concentration, and the corresponding removal rate reached 98.03%. The adsorption kinetics were studied by using a pseudo-first-order and pseudo-second-order (PFO–PSO) combined model. Results revealed that HISADP adsorption by QAMCM is a complex process because of the involvement of both chemisorption and physisorption instead of only one mechanism. However, chemisorption (electrostatic attraction and electron sharing) is the dominant kinetic mechanism. Analysis of the mass transfer mechanisms showed that the dynamic characters of the adsorption capacities of the liquid film around QAMCM and the pores of QAMCM could be well described using a film–pore mass transfer model, which could be used to provide insights into the adsorption mass transfer behaviors of the system. Additionally, HISADPs with smaller sizes were preferentially adsorbed by QAMCM compared with larger ones. Research on the isotherms and thermodynamics showed that HISADP adsorption by QAMCM occurred via an endothermic multi-layer process and was spontaneous. Overall, QAMCM was found to be an efficient, green, and recyclable decolorization adsorbent for beet juice.

Chloromethylfurfural (CMF), a valuable intermediate for the production of chemicals and fuels, can be derived in high yields from the cellulose component of biomass. This study examined the effect of sugarcane bagasse components and biomass architecture on CMF/bio-oil yield using a HCl/dichloroethane biphasic system. The type of pretreatment affected bio-oil yield, as the CMF yield increased with increasing glucan content. CMF yield reached 81.9% with bagasse pretreated by acidified aqueous ionic liquid, which had a glucan content of 81.6%. The lignin content of the biomass was found to significantly reduce CMF yield, which was only 62.3% with an acid-catalysed steam exploded sample having a lignin content of 29.6%. The change of CMF yield may be associated with fibre surface changes as a result of pretreatment. The hemicellulose content also impacted negatively on CMF yield. Storage of the bio-oil in chlorinated solvents prevented CMF degradation.

The combination of dwindling petroleum reserves and population growth make the development of renewable energy and chemical resources more pressing than ever before. Plant biomass is the most abundant renewable source of energy and chemicals. Enzymes can selectively convert the polysaccharides in plant biomass into simple sugars which can then be upgraded to liquid fuels and platform chemicals using biological and/or chemical processes. Pretreatment is essential for efficient enzymatic saccharification of plant biomass and this article provides an overview of how organic solvent (organosolv) pretreatments affect the structure and chemistry of plant biomass, and how these changes enhance enzymatic saccharification. A comparison between organosolv pretreatments utilizing broadly different classes of solvents (i.e., low boiling point, high boiling point, and biphasic) is presented, with a focus on solvent recovery and formation of by-products. The reaction mechanisms that give rise to these by-products are investigated and strategies to minimize by-product formation are suggested. Finally, process simulations of organosolv pretreatments are compared and contrasted, and discussed in the context of an industrial-scale plant biomass to fermentable sugar process.

Simple lignin model compounds containing β-O-4 aryl ether linkages have been utilized as a means to understand lignin depolymerisation. The effects of reaction temperature, time, catalyst concentration, and initial phenethoxybenzene (PEB) concentration on the degradation of PEB in NaOH were investigated. Operating at 300 °C for 1 h resulted in the highest combined yield of the primary products, phenol and styrene, and also resulted in a reduced amount of degradation products formed. The proportion of oligomeric and polymeric materials formed depended on the NaOH concentration, but not on the initial PEB concentration for equal reaction time. The results were used to suggest probable reaction pathways for PEB degradation.

A major challenge that must be overcome for the commercial production of levulinic acid from lignocellulosics is to reduce equipment blockage and corrosion. Methanesulfonic acid (MSA), a relatively low corrosive acid, was used to produce organic acids and furfural from pretreated sugarcane bagasse. In general, the type of pretreatment did not affect levulinic acid yield, though it affected furfural yield. However, soda pretreated bagasse produced the highest yields of levulinic acid (∼75 mol%) and furfural (∼85 mol%), albeit under optimized conditions. Hydrolysis residue consists primarily of lignin that has been modified and/or condensed to humic substances, fatty acids, and oligomeric sugars. A conceptual biorefinery utilizing 1 ton of dry bagasse, alkaline-pretreatment, and MSA as a catalyst produced 165 kg soda lignin, 190 kg and 89 kg of levulinic acid and formic acid respectively, and 40 kg furfural.

5-hydroxymethylfurfural (HMF) is a suitable platform chemical for the production of useful chemicals and fuels. This study examined the hydrolysis of mixtures of sucrose, glucose and fructose (synthetic sugar cane molasses) and industrial molasses using sulfonated carbon-based heterogeneous catalysts derived from sugar cane bagasse (B-SO3H) and sugar cane molasses (M-SO3H). Microwave heating at 150 °C for 4 h produced 39 mol % HMF yield with B-SO3H on the synthetic sugar solution. The addition of a molasses pretreatment step, as well as, increasing the microwave power was necessary to achieve similar HMF yields with the industrial molasses sample. The hydrolysis of molasses pretreated with formic acid or HCl resulted in a slightly higher HMF yield than the hydrolysis of molasses pretreated with H2SO4. The buffering capacity of the formic acid pretreated molasses was lowered through dilution with water; and subsequently HMF yield was increased to 64.3 mol % (170 °C, 3 h).

10 páginas.-- 4 figuras.-- 3 tablas.-- 54 referencias.-- The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acssuschemeng.7b00274., Commercial furfural, an important platform chemical, is produced from acid hydrolysis of lignocellulosic biomass. The manufacturing processes are inherently inefficient, and so it is necessary to value add to substantial amounts of residue obtained. The structural features of bagasse furfural residue and the lignins extracted from it by three NaOH treatments have been studied in order to understand the transformations that occurred by these treatments. 2D-NMR and Py-GC/MS of the furfural residue revealed that it contains mostly lignin and depolymerized cellulose moieties and the complete absence of xylans as a result of their hydrolysis during the furfural production process. In addition, the analyses revealed that the furfural residue contains 44% of H-type lignin units, in comparison to 11% for bagasse, and most of the lignin interunit linkages present in bagasse have disappeared. The pyrograms show that the furfural residue produced unusually high phenol content, which was attributed to the high levels of “H-type” units present in this lignin. The proportion of functional groups, particularly total OH aliphatic groups, where significantly lower in the extracted lignins compared to soda lignin obtained by the normal pulping process. The highest severity of the NaOH extraction process reduced the amount of reactive functional groups present in the lignin, though the S/G ratios of ∼1.1 were independent of the extraction method. The three lignins have high proportions of “H-units” (around 36–37%), which gives them special properties for different applications, particularly in the production of phenolic resins., This study was partly funded by Sugar Research Australia, formerly Sugar Research Development Corporation (QUT004). JoséC. del Rio, Jorge Rencoret, and Ana Gutierrez were partially funded by the Spanish projects AGL2014-53730-R and CTQ2014-60764-JIN (cofinanced by FEDER funds)

Chemical hydrolysis processes are the focus of this chapter with regard to conversion of the carbohydrate content of lignocellulosic biomass such as bagasse to chemicals. Furans and organic acids such as levulinic acid and formic acid can be produced through acid-catalyzed dehydration and hydrolysis of hexose and pentose sugars. New technologies and processing environments that allow the use of biphasic systems and/or continuous extraction of products would increase reaction rates, yields, and product quality to provide the necessary step change for optimization of key reactions. The choice of solvent in an industrial process is influenced by polarity, boiling point, and partitioning ability as these provide a key measure on the recovery of product, catalyst, and solvent. As an alternative to direct production of levulinic acid or furanic products, solvolysis reactions can produce other chemical products in either one-pot or sequential reactions. The chapter discusses a number of potential products.

12 páginas.-- 6 figuras.-- 6 tablas.-- 52 referencias.-- The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acssuschemeng.6b01093., Dilute acid pretreatment is one of the most studied biomass deconstructing technologies due to its relatively low process cost. Typical cellulosic ethanol production process involves three main stages: (1) dilute acid pretreatment, (2) enzymatic hydrolysis, and (3) fermentation/distillation. In this study, three lignins, L1, L2, and L3, were extracted using 1% (w/w) NaOH solution at 80 °C following each stage, respectively. Lignin characterization shows the reduction of aliphatic, guaiacyl, and carboxylic OH groups of the L2 and L3 compared to those of the L1 but increases in both the weight and number molecular weights as well as slight increases in the polydispersity index, probably because, among other reasons, of the removal of a higher molecular weight lignin fraction from the pretreated biomass during enzymatic hydrolysis. While 2D HSQC NMR and Py-GC/MS did not reveal differences in the proportions of syringyl and p-hydroxyphenyl units among the lignins, there is a predominance of the phenylcoumaran substructures and guaiacyl lignin units in L1 and the absence of some substructures/linkages associated with L2 and L3. Lignin extraction following dilute acid pretreatment not only produced the lignin with the highest purity but also resulted in improved glucose yield from 71% to 77%., This study was partly funded by the Australian Indian Strategic Research Fund (AISRF) Grand Challenge Project (GCF020010). Jose Rio, Jorge Rencoret, and Ana Gutierrez who conducted the analytical pyrolysis work were partially funded by the Spanish projects AGL2014-53730-R and CTQ2014-60764-JIN (cofinanced by FEDER funds).