Estudos de caracterização e desconstrução de biomassas de eucalipto e capim elefante para aplicações em biorrefinarias integradas à indústria de celulose

• Autor(a) principal: Gomes, Fernando José Borges
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/595
• topic: Biocombustíveis; Biomassa; Celulose; Eucalipto; Biofuels; Biomass; Cellulose; Eucalyptus; CNPQ::CIENCIAS AGRARIAS::RECURSOS FLORESTAIS E ENGENHARIA FLORESTAL::TECNOLOGIA E UTILIZACAO DE PRODUTOS FLORESTAIS

The great challenge of modern civilization is becoming a sustainable society based on rational utilization of natural resources. In this scenery, the biorefinery concept came up, which refers to the conversion of lignocellulosic materials into bioproducts (pulp, chemicals, etc.) and bioenergy (ethanol, energy, etc.) with minimal emissions and low waste. The biorefinery concept is based on many different kinds of biomass such as agricultural and forest wastes, wood, and grasses in general, etc. For applying this concept, the pulp and paper industries are an ideal place, since they have all infrastructures for the harvesting, transportation, storage, and handling of large volumes of biomass, for partial biomass deconstruction, burning of the process wastes, aiming energy generation, and for the treatment of the solids and gas wastes, etc. One of the great challenges to the biorefineries is the wide range of raw materials to be processed, which presents different characteristics and behaviors during the deconstruction processes. This work aimed to investigate the biorefinery processes of a new generation eucalypt clones and elephant grass aiming pulp and cellulosic ethanol production. This thesis is divided in five chapters, namely: (1) literature review on biorefinery processes integrated to the pulp industry, (2) thorough characterization of Brazilian new generation eucalypt clones and elephant grass, (3) evaluation of alkaline deconstruction processes for Brazilian new generation of eucalypt clones, (4) evaluation of Brazilian new generation of eucalypt clone for biofuel production, (5) potential of elephant grass for pulp production. In Chapter 1, it was made a literature review on the integration of biorefinery processes associated with the pulp industry, with emphasis on the cellulosic ethanol production as a byproduct, focusing on technologies acids, neutral and alkaline pretreatment, enzymatic saccharification and fermentation of C6 and C5 sugars in separate and simultaneous processes. In Chapter 2, it was evaluated the quality of 18 eucalypt clones and 2 species of elephant grass for the production and pulp and biorefinery processes. The goal of this chapter was to select the four most promising clones of eucalypts and one species of elephant grass for subsequent studies. For this, a thorough investigation of the samples, which contemplated analyses of forestry productivity, density, moisture content, morphology and chemical composition, was performed. In Chapter 3, it was investigated for the four eucalypt clones chosen previously in Chapter 2, regarding their behavior when submitted to the alkaline deconstruction processes (soda-AQ, soda-AQ-O2, soda-O2, and Kraft), which were evaluated considering their screening yield, alkali charge and viscosity for different kappa number levels. The two most promising processes for producing pulp (kraft and soda-AQ) were studied in details through the pulp production aiming kappa numbers 15 and 20 regarding their composition and structure (content of carbohydrates, uronic acid, hexenuronic acid, carbohydrate molecular weight, structure of residual lignin), as well as for their respective black liquors (heating value, solid content, elemental analysis, and lignin structure). In Chapter 4, it was investigated two kinds of alkaline deconstruction processes (soda-AQ and soda-O2), which are most promising for bioethanol production, being used as a raw material the eucalypt clone G1xUGL. The processes of deconstruction were conducted aiming different levels of kappa number (15, 35, 50 and 70). After this step, a stage of saccharification followed by another of fermentation of the samples was performed. In Chapter 5, the potential of elephant grass for pulp production was evaluated in comparison with a eucalypt clone by using alkaline processes (kraft and soda-AQ) terminated at kappa numbers 15 and 20, through the screened yield, alkali charge, viscosity and bleachability. The main findings of this work were: (Chapter 1) besides the biomass pretreatments improvement and processes for biomass deconstruction, enzymatic conversion of polysaccharides in the lignocellulosic biomass will be a key technology in future biorefineries; (Chapter 2) the eucalypt clones showed a higher potential for biorefinery applications than the elephant grass due to their high dry biomass production per hectare, high density and contain fewer minerals and extraneous materials, highlighting the eucalypt clones U1xU2, G1xUGL, DGxU2, and IP; between the elephant grass, the EG1 (Pennisetum purpureum) sample was chosen due to its highest productivity (32 ton/ha/yr) and density (216 kg/m3); (Chapter 3) soda-AQ and Kraft showed to be the best processes for producing pulp. The alkaline processes using oxygen (soda-AQ-O2 and soda-O2) are more indicated for working as alkaline pretreatment method to be used in lignocellulose biorefineries; (Chapter 4) the soda-O2 process at kappa number levels of 35-50 provided the best potential for cellulosic ethanol production, with the best rate of saccharification (73%). These levels of sugar released are high and warrant efficient production of ethanol with yield above 370 L/t of dry wood; (Chapter 5) although the elephant grass showed a high extractive and minerals content, it proved as a potential raw material for pulp production, being the ideal cooking processes the Kraft at kappa number 20 or soda-AQ at kappa number 15.