Optimization of furfural production by acid hydrolysis of Eucalyptus globulus in two stages

Abstract

The aim of this study was to optimize the production of furfural by hydrolysis with dilute acid of Eucalyptus globulus wood in two stages, using a factorial experimental design and multiple regression models to maximize furfural yields. The two-stage process could provide a solid phase with less degraded cellulose and older applications that the solid phase of a conventional acid hydrolysis. The selectivity for furfural of the process was increased by effect of the glucan and lignin fractions being efficiently removed after the first acid hydrolysis stage.The operational ranges are especially suitable for the extraction of xylose, which was virtually quantitative at 170 ºC and virtually independent of the operation time. It is therefore advisable to use non-isothermal conditions or short times. This is quite important if one considers the low acid concentration used. The liquid phase obtained after autohydrolysis of the raw material under the optimum conditions contained 2.3% glucose, 9.8% xylose, 2.5% xylo-oligomers, 0.6% arabinose, 1.1% furfural and 0.1% 5-OH methyl furfural.After the residual solid from the first hydrolysis stage is removed, the acid concentration is the most influential variable on the conversion of xylo-oligomers or xylose into furfural. Conversions to furfural were quite substantial (greater than 10 g/L). Hemicelluloses in the raw material were extracted by 32-57.7% and xylan by 40.5-84%. The highest conversions to furfural were obtained by using a medium operation time (15 min) and low temperature (170 ºC) and pH=2.The process additionally provides hemicellulose derivatives that are scarcely contaminated with cellulose derivatives. The concentrations of gluco-oligomers were very low and those of glucose in the region of 3% of the raw material.Response to Reviewers: Optimization of furfural production by acid hydrolysis of Eucalyptus globulus in two stages. Ms. Ref. No.: CEJ-D-13-02942 LIST OF CHANGES Reviewers' comments:REVIEWER 1: The manuscript dealed with the furfural production from woody biomass. If the manuscript just focused on the optimization of two stage of furfural production, the novelty seems not enough. The authors were suggested to provide some evidences for advantages of two stage process as compared with single stage. In many parts, the writing hard to be understood. RESPONSE TO REVIEWER COMMENT:(*) The use of lignocellulosic biomass as a sustainable, renewable raw material for the production of chemicals and energy is steadily gaining interest. Despite the difficulties, especially as regards the need to fractionate its components in order to make the process cost-effective, there is increasing experimental evidence of its viability. For example, research has shown the possibility of obtaining ethanol as main product, but also that other structural components such as hemicelluloses and polyphenols (lignin) can be useful to obtain foods, pharmaceuticals, plastics, paper and basic chemicals, among others, by using a series of process known as "Biorefining". An ...

Lignocellulose biorefinery product engineering

“…What is more, furfural and its derivatives have the potential to serve as gasoline blend stock (López et al, 2014). Furfural and its derivatives are considered in many instances to be strategic chemicals based on their various applications and use.…”

Maximizing furfural concentration from wheat straw and Eucalyptus globulus by nonisothermal autohydrolysis

“…Furfural is an important organic chemical produced from agroindustrial wastes and residues [9], and it is used mainly in the production of resin, which is then used as a binding agent in foundry technologies. It is also used for the production of a wide range of important nonpetroleum-derived chemicals, such as furan, tetrahydrofuran, and furfural alcohol; it is also used as an extractive fungicide, nematocide, in oil refineries, as well as in the plastics, food, pharmaceutical, and agricultural industries [11]. Moreover, furfural has got other main applications like in grinding and abrasive wheels, in pharmaceuticals, and in the manufacture of phenolic resins [9], and it is highly regarded for its thermosetting properties, physical strength, and corrosion resistance [10].…”

“…Steam explosion and dilute acid pretreatment are the two most commonly used methods because of their effectiveness and inexpensiveness [11]. Hot water or weak acid hydrolysis at an elevated temperature is the first step that is typically used to hydrolyze carbohydrates from LCMs.…”

“…Moreover, furfural has got other main applications like in grinding and abrasive wheels, in pharmaceuticals, and in the manufacture of phenolic resins [9], and it is highly regarded for its thermosetting properties, physical strength, and corrosion resistance [10]. It is also used for the production of a wide range of important nonpetroleum-derived chemicals, such as furan, tetrahydrofuran, and furfural alcohol; it is also used as an extractive fungicide, nematocide, in oil refineries, as well as in the plastics, food, pharmaceutical, and agricultural industries [11]. There is no synthetic route available for furfural production in the chemical industry.…”

Chemical Pretreatments of Wood Chips Prior to Alkaline Pulping - A Review of Pretreatment Alternatives, Chemical Aspects of the Resulting Liquors, and Pulping Outcomes

“…From pentoses (such as xylose), the main degradation product formed under acidic conditions is FF (Qi and Xiuyang 2007;Agirrezabal-Telleria et al 2013Liu et al 2014;López et al 2014). From hexoses, which are more stable than pentoses under acidic conditions, the primary degradation product is HMF.…”