Análise termogravimétrica da pirólise do material carbonáceo obtido do biorrefino do bagaço de cana-de-açúcar em ácido levulínico
Data
2020-10-15
Autores
Bettarello, Carolinne Sanches 
Goneli, Michelino Amorim
Orientadores
Tovar, Laura Plazas
Tipo
Trabalho de conclusão de curso
Título da Revista
ISSN da Revista
Título de Volume
Resumo
O bagaço de cana-de-açúcar (BCA) possui enorme potencial energético, uma vez que
detém grande quantidade de celulose, propiciando a obtenção de substâncias de alto valor
agregado, como o ácido levulínico (AL). Nesse contexto, surgem as huminas, componentes
sólidos de estrutura complexa, as quais podem ser originadas a partir de diferentes cenários da
produção de AL. A valorização dessas huminas, a qual pode ser realizada pelo processo de
pirólise, é essencial para incrementar a conversão de carbono inicial da celulose do BCA. Neste
trabalho, duas huminas (HU) derivadas do biorrefino do bagaço de cana-de-açúcar (em um
trabalho anterior) foram investigadas: HU-cn1: material obtido por tratamento catalisado por
ácido em três etapas e HU-cn2: material obtido no processo de biorrefino catalítico em uma
etapa. A análise imediata das HU confirma que a matéria volátil (54,11% e 51,99%) e o carbono
fixo (42,85% e 42,73%) das HU-cn1 e HU-cn2, respectivamente, atribui a maior parte de seu
poder calorífico superior (23,57 e 24,26 MJ kg-1
, respectivamente). A degradação térmica de
ambos os materiais carbonáceos foi investigada por análise termogravimétrica não-isotérmica,
utilizando um modelo de reação global. A energia de ativação foi estimada usando o método
isoconversional de Friedman, analisando sua dependência da conversão. Dessa forma, foram
determinados os parâmetros cinéticos para a pirólise das huminas, obtidas pelo biorrefino da
cana-de-açúcar. Foi possível constatar uma porcentagem de massa residual de,
aproximadamente, 42% (para HU-cn1) e entre 53% e 72% (para HU-cn2). Os valores médios
de energia de ativação calculados foram 115,55±52,57 kJ mol-1
e 61,14±34,42 kJ mol-1
, para as
amostras HU-cn1 e HU-cn2, respectivamente. O método master-plot constatou que os modelos
de pirólise mais prováveis são os mecanismos de reação química de terceira e segunda ordem,
para HU-cn1 e para HU-cn2 respectivamente. Contribuiu-se substancialmente à consolidação
da bioplataforma à base de carbono via pirólise, visando o desenvolvimento de futuras
produções sustentáveis, baseadas na química verde.
Sugarcane bagasse (SB) has an enormous energy potential given that it contains a great amount of cellulose, which can be converted to high added value substances, such as levulinic acid (LA). In this context, the humins, solid material of a complex structure, is a byproduct obtained from different scenarios of LA production. Humins valorization can be carried out by a pyrolysis process and it is essential to improve the initial carbon conversion of cellulose from SB. In this study, two humin (HU) samples obtained by the SB biorefinery process (from a previous study) were investigated: HU-cn1: sample obtained by a three-step acid-catalyzed treatment. HU-cn2: sample obtained by a one-step catalytic biorefinery process. The proximate analysis of HU confirmed that a volatile matter of 54,11% and 51,99% and fixed carbon of 42,85% and 45,73% for HU-cn1 and HU-cn2, respectively, assigns most of its higher heating value (23,57 and 24,26 MJ kg-1, for HU-cn1 and HU-cn2, respectively). Thermal decomposition of both carbonaceous materials was conducted by non-isothermal thermogravimetric analysis and examined by the one-step reaction model. The activation energy was calculated using Friedman’s isoconversional method, analyzing its dependency on conversion. Solid residue was approximately 42% (for HU-cn1) and ranging from 53% to 72% (for HU-cn2). The average activation energy values determined were 115,55±52,57 kJ mol-1 and 61,14±34,42 kJ mol-1, for HU-cn1 and HU-cn2, respectively. The master-plot approach suggested that the third- and second-order chemical reaction mechanisms are the most likely pyrolysis models for HU-cn1 and HU-cn2, respectively. This study substantially contributed to the carbon-based bioplataform consolidation via pyrolysis, aiming the development of future sustainable production, based on the green-chemistry
Sugarcane bagasse (SB) has an enormous energy potential given that it contains a great amount of cellulose, which can be converted to high added value substances, such as levulinic acid (LA). In this context, the humins, solid material of a complex structure, is a byproduct obtained from different scenarios of LA production. Humins valorization can be carried out by a pyrolysis process and it is essential to improve the initial carbon conversion of cellulose from SB. In this study, two humin (HU) samples obtained by the SB biorefinery process (from a previous study) were investigated: HU-cn1: sample obtained by a three-step acid-catalyzed treatment. HU-cn2: sample obtained by a one-step catalytic biorefinery process. The proximate analysis of HU confirmed that a volatile matter of 54,11% and 51,99% and fixed carbon of 42,85% and 45,73% for HU-cn1 and HU-cn2, respectively, assigns most of its higher heating value (23,57 and 24,26 MJ kg-1, for HU-cn1 and HU-cn2, respectively). Thermal decomposition of both carbonaceous materials was conducted by non-isothermal thermogravimetric analysis and examined by the one-step reaction model. The activation energy was calculated using Friedman’s isoconversional method, analyzing its dependency on conversion. Solid residue was approximately 42% (for HU-cn1) and ranging from 53% to 72% (for HU-cn2). The average activation energy values determined were 115,55±52,57 kJ mol-1 and 61,14±34,42 kJ mol-1, for HU-cn1 and HU-cn2, respectively. The master-plot approach suggested that the third- and second-order chemical reaction mechanisms are the most likely pyrolysis models for HU-cn1 and HU-cn2, respectively. This study substantially contributed to the carbon-based bioplataform consolidation via pyrolysis, aiming the development of future sustainable production, based on the green-chemistry