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Analysis of Hydrolysis Yields by Using Different Acids for Bioethanol Production from Brazilian Woods

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Analysis of Hydrolysis Yields by Using Different Acids for Bioethanol Production from Brazilian Woods XVII INTERNATIONAL CONFERENCE ON INDUSTRIAL ENGINEERING AND OPERATIONS MANAGEMENT Technological Innovation and Intellectual Property: Production Engineering Challenges in Brazil Consolidation in the World Economic Scenario. Belo Horizonte, Brazil, 04 to 07 October – 2011 ANALYSIS OF HYDROLYSIS YIELDS BY USING DIFFERENT ACIDS FOR BIOETHANOL PRODUCTION FROM BRAZILIAN WOODS Diogo Jose Horst (UTFPR) [email protected] Jhon Jairo Ramirez Behainne (UTFPR) [email protected] Rodolfo Reinaldo Petter (UTFPR) [email protected] In this work, the wood´s hydrolysis yields using different mineral acids H2SO4, HNO3, H3PO4, and CH3COOH were analyzed in order to identify the better for ethanol production levels. Twelve Brazilian biomasses, including native and exotic sppecies in the form of wood chips were prepared to produce ethanol and cellulosic fibers simultaneously. For fermentation, a savage line of Saccharomyces cerevisiae strain was chosen. Income related to hydrolysis efficiency, ethanol yields, fibrous fractions efficiency, starch and glucose levels plus delignification efficiency were tested and proved in laboratory. From the results it is possible to join the production of ethanol and cellulosic fibers simultaneously from wood chips, and because of the complexity of the material used as samples is possible to isolated several chemical derivatives that can be developed and contribute to enrichment of further studies. The acids tested showed to be potentially utilized in hydrolysis processes as well. Palavras-chaves: Acid hydrolysis, Ethanol production, Wood. XVII INTERNATIONAL CONFERENCE ON INDUSTRIAL ENGINEERING AND OPERATIONS MANAGEMENT Technological Innovation and Intellectual Property: Production Engineering Challenges in Brazil Consolidation in the World Economic Scenario. Belo Horizonte, Brazil, 04 to 07 October – 2011 1. Introduction There is a considerable potential to modernize the use of biomass fuels to produce convenient energy vectors such as electricity, gas and automotive fuels, while the traditional uses of biomass is preserved. When produced in sufficient and sustainable way energy from biomass brings many environmental and social benefits compared with other fossil fuels. Some geopolitical factors related to the security of oil supply, high prices and serious environmental concerns, like global warming, are essential to sustainability through alternative fuels such as ethanol (COPOLLA et al. 2009). Using ethanol instead of petroleum derivatives is advantageous in many aspects (KRISHNA et al., 2001 and ZHU et al. 2010). The development of new technologies for treatment of lignocellulose materials for ethanol production is well regarded by the world, both economically and environmentally, as compared to fossil fuel production. Today, ethanol is one of the most important alternative fuels that can be obtained through the fermentation of sugars using a biological catalyst, such as yeast. Processes for producing ethanol using yeast have been extensively investigated. In an attempt to minimize the production costs, the use of cellulosic materials, which includes agro-industrial residues and wood waste, appears as important source of carbohydrates for fermentation of biomass (SUN, 2002 and CHENG, 2004). Wood is a complex substance of polymeric character. Some 40% to 50% by weight of dry wood consists of cellulose, which is a fiber of great commercial value. The cell walls consist of polysaccharides, lignin and holocellulose. The holocellulose is a mixture of short- chain polymers such as arabinose (C5H10O5), galactose (C6H12O6), glucose (C6H12O6), mannose (C6H12O6) and xylose (C5H10O5). Lignin is a complex polymer of substituted phenols that act as ligands of cellulose fibers (FENGEL and WEGENER, 1989). Cellulose can be hydrolyzed by the action of mineral acids, unfolding into glucose. This glucose can be fermented by yeast to produce alcohol. In nature, these processes are carried out by fungi and bacteria, which secrete enzymes that break down the cellulose molecules, which are called cellulases, and also by yeasts that ferment sugars into alcohol. The technological process of producing ethanol from cellulosic material can be schematically divided and three stages: extraction of sugars from the raw material, fermentation of sugars, distillation and rectification of fermented alcohol contained in the fermented wine. In most cases a pre- saccharification hydrolysis is included in the procedure to remove the more easily hydrolysable polyoses before the main hydrolysis of cellulose. The greatest potential for utilization of glucose is fermented to produce ethanol, but other valuable products can also be derived from glucose wood (LEWIN; GOLDSTEIN, 1999; MARTÍN et al. 2003). All natural lignocellulosic material and most refined must be submitted to a pretreatment which cellulosic biomass becomes susceptible to hydrolytic enzymes. Generally, the yield of hydrolysis, without the phase of pre-treatment, 20% of theoretical yield, while the yield after pre-treatment is often greater than 90% of theoretical yield. It is assumed that the limited effectiveness of current enzymatic processes with soft wood is due to the relative difficulty of performing the pre-treatment of these materials. A study was conducted on the pre-treatment (MCMILLAN, 1994 and YANG et al 2006). The hydrothermal treatment using 2 XVII INTERNATIONAL CONFERENCE ON INDUSTRIAL ENGINEERING AND OPERATIONS MANAGEMENT Technological Innovation and Intellectual Property: Production Engineering Challenges in Brazil Consolidation in the World Economic Scenario. Belo Horizonte, Brazil, 04 to 07 October – 2011 water at temperatures of 170 °C to 220 °C has been applied for pretreatment of lignocellulose material aimed at the solubilization of lignin, hemicellulose and providing these polymers for subsequent enzyme treatment leading to production of glucose and other saccharides that may be used in bioprocesses of commercial interest (CHUM et al., 1990; ZHU et al. 2010). Hydrolysis of cellulosic biomass in mineral acid is one of the major methods employed to separate lignin and monosaccharides from lignocellulosic biomass, however, this process is strongly dependent on the acid concentration and temperature. It has been reported that at low mineral acid concentrations, high temperature is required to achieve significant hydrolysis, thus requiring high energy loading. Although a high mineral acid concentration can significantly reduce temperature or the energy requirement, higher than 20% concentration of mineral acids would be needed. The process does not provide a promise for substantial industrial gains (Sasaki et al., 1998 and Iranmahboob et al., 2002; and Kakanson, Ahlgren, 2005) because of the difficulties in reusing and recycling the mineral acid. Therefore, establishment of an effective and environmentally benign hydrolysis process is of great significance to the conversion and the utilization of lignocellulosic biomass. During hydrolysis, however, are toxic compounds produced derivatives of furfur (2- furaldehyde and 5-hydroxymethyl-2-furaldehyde), degraded phenolic compounds and organic acids that can often inhibit or undesirably affect the performance of biocatalysts in bioprocesses on interfering ferment ability when in concentrations above 1% in weight (WOICIECHOWSKI et al., 2000). The control of the hydrolysis process aims to minimize the concentrations of toxic compounds, currently; different treatments are being used for improving the capacity of fermentation of hemicellulose hydrolyses (PALMQVIST et al., 1999, CARDONA et al., 2010; XAVIER et al., 2010; ZHU et al., 2010). The aim of this study was investigate the hydrolysis yields using mineral acids: sulfuric (H2SO4), nitric (HNO3), phosphoric (H3PO4), and acetic (CH3COOH), in order to find which hydrolysis process is more advantageous for Brazilian wood. Also, a theoretical projection was carried out to determine the ethanol yield produced on liters per 100 kg of biomass, as well as the delignification and samples fibrous fractions efficiency. The samples used in this paper consisted in chips from twelve Brazilian species of wood, among them some native and exotic species in the form of wood chips and sawdust. These biomasses were utilized because they are considerate of low commercial value and currently burned in boilers to steam generation and power cogeneration. This research contributes by generating new information about the performance of acid hydrolysis of Brazilian wood species that had no been until now studied, which is important to identify new biomass and new acids for hydrolysis with potential for ethanol production. 2. Materials and Methods 2.1 Raw materials The lignocellulosic waste used in this study was supplied by furniture companies of the city of São Bento do Sul, localized in Santa Catarina State. The raw material consists of chips and sawdust obtained directly from the industrial process. The samples analyzed consisted of particles with 0.2 to 2.7 mm of diameter, (90% or more particles pass through a 3 XVII INTERNATIONAL CONFERENCE ON INDUSTRIAL ENGINEERING AND OPERATIONS MANAGEMENT Technological Innovation and Intellectual Property: Production Engineering Challenges in Brazil Consolidation in the World Economic Scenario. Belo Horizonte, Brazil, 04 to 07 October – 2011 40 mm sieve). All lignocellulosic materials used in this research were collected in the moment that the timber passed through the machining process. The wood chips were packed in containers of 5 kg each,
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