Estudo da produção de biodiesel via catálise enzimática
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Tipo de produção
Dissertação
Data
2018
Autores
Silva, M. S. R.
Orientador
Marin, M. P. A.
Periódico
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Citação
SILVA, M. S. R. Estudo da produção de biodiesel via catálise enzimática. 2018. 154 f. Dissertação (Mestrado em Engenharia Química) - Centro Universitário FEI, São Bernardo do Campo, 2018 Disponível em: <https://doi.org/10.31414/EQ.2018.D.129819>. Acesso em: 30 jul. 2018.
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Palavras-chave
Biodiesel,Óleo de soja,Transesterificação,Energias renováveis
Resumo
Entre as fontes de energia alternativas ao diesel de petróleo, destaca-se o biodiesel. Atualmente, é produzido a partir de um catalisador homogêneo básico, o que pode gerar problemas ambientais, como o gasto excessivo de água na purificação dos produtos. A fim de propor uma rota mais limpa, o presente trabalho investigou a produção de biodiesel via catálise enzimática, tendo o óleo de soja e o metanol como reagentes e a enzima imobilizada Novozyme 435® como catalisador. Para tal, foram avaliados o uso de cossolventes (neste caso, o tercbutanol e o hexano), a adição de água, a razão molar de metanol/óleo, a quantidade de catalisador na reação, a conversão ao longo do tempo, bem como o equilíbrio de fases a partir do programa ASPEN Plus®. Dentre os resultados, viu-se que, do lado dos ossolventes, a uma razão volumétrica de 8:1 de óleo/terc-butanol, a conversão atingiu 76%, enquanto que com
razão volumétrica de 1:4 de óleo/hexano, a conversão máxima foi de 43%. Sobre a adição de água, verificou-se que, quanto maior a quantidade desta, menor foi a conversão em biodiesel, não favorecendo a reação. Do mesmo modo, observou-se que um excesso de metanol também não facilitou o processo, uma vez que, com razão molar de 3:1 metanol/óleo, a conversão foi de 66%, sendo 10% menor que quando utilizada razão molar de 4:1. Em seguida, averiguou-se que a quantidade de enzima necessária foi de 2% em massa de enzima em relação à de óleo,
convertendo 77%, visto que, com valores maiores, a conversão manteve-se a mesma. Já o experimento de conversão no tempo mostrou que foram necessárias 44 horas para uma conversão de 78,6%, entretanto, uma análise econômica poderia determinar o melhor tempo de reação. Por último, a simulação do equilíbrio de fases mostrou que, quanto mais hexano no sistema, maior a concentração de metanol na fase que contém óleo, diminuindo a conversão
pelo efeito inibidor que o álcool tem na enzima. Já com o terc-butanol, deu-se que, quanto menor a quantidade de cossolvente, maior a concentração de metanol na fase que contém óleo. Apesar do sistema permanecer em duas fases nas condições testadas, a concentração de metanol na faixa que contém óleo é alta o suficiente para se obter boas conversões e baixa o bastante para não desnaturar a enzima. A proposta do processo enzimático, comparado ao alcalino, é vantajoso na separação e purificação dos produtos, não necessita de água de lavagem e nem faz
uso de ácido para neutralização, mostrando-se uma rota mais limpa. Além disso, o ciclo de separação tem menor gasto energético, com economia de 233% de água de resfriamento e de 34,4% de energia.
Among the alternative sources of energy to diesel oil is biodiesel. Nowadays, it is produced from a basic homogeneous catalyst, which can cause environmental problems, such as excessive waste of water during purification of products. In order to propose a cleaner route, this study investigated the production of biodiesel through enzymatic catalysis, with soybean oil and methanol as reagents and immobilized enzyme Novozyme 435® as catalyst. Thereunto, a variety of tests were made, such as the use of cosolvents (in this case, tert-butanol and hexane), the addition of water, the molar ratio of methanol/oil, the amount of catalyst in the reaction, the conversion over time, as well as the phase balancing with ASPEN Plus® software. From the results it was found that, about the cosolvents, at a volume ratio of 8:1 oil/tert-butanol, the conversion reached 76%, while at the volumetric ratio of 1:4 oil/hexane, the maximum conversion was 43%. Regarding the addition of water, it was verified that the higher the amount of water, the lower the conversion to biodiesel, not favoring the reaction. Likewise, it was observed that an excess of methanol also did not benefited the process, since a molar ratio of 3:1 methanol/oil, converted 66% to biodiesel, being 10% less than the molar ratio of 4:1. Then, it was found that the appropriate amount of enzyme was 2% by mass of enzyme over oil, converting 77%, being that the conversion remained the same with larger values. The time conversion experiment showed that it took 44 hours for a conversion of 78.6%, however, an economic analysis could determine the best time for the reaction. Finally, the equilibrium of phases simulation showed that the more hexane in the system, the higher the concentration of methanol in the oil-containing phase, reducing the conversion because of the inhibitory effect that alcohol has on the enzyme. With tert-butanol, it was found that the lower the amount of cosolvent, the higher the concentration of methanol in the oil-containing phase. Although the system remained in two stages under the tested conditions, the concentration of methanol in the oil-containing phase showed to be high enough to generate good conversions and low enough to not denature the enzyme. The proposed enzymatic process, compared to the alkaline, has advantages in separating and purifying the products, it does not require washing water and neither the use of acid for neutralization, proving to be a cleaner route. In addition, in this case, the separation cycle has lower energy expenditure, with a saving of 233% of cooling water and 34.4% of energy.
Among the alternative sources of energy to diesel oil is biodiesel. Nowadays, it is produced from a basic homogeneous catalyst, which can cause environmental problems, such as excessive waste of water during purification of products. In order to propose a cleaner route, this study investigated the production of biodiesel through enzymatic catalysis, with soybean oil and methanol as reagents and immobilized enzyme Novozyme 435® as catalyst. Thereunto, a variety of tests were made, such as the use of cosolvents (in this case, tert-butanol and hexane), the addition of water, the molar ratio of methanol/oil, the amount of catalyst in the reaction, the conversion over time, as well as the phase balancing with ASPEN Plus® software. From the results it was found that, about the cosolvents, at a volume ratio of 8:1 oil/tert-butanol, the conversion reached 76%, while at the volumetric ratio of 1:4 oil/hexane, the maximum conversion was 43%. Regarding the addition of water, it was verified that the higher the amount of water, the lower the conversion to biodiesel, not favoring the reaction. Likewise, it was observed that an excess of methanol also did not benefited the process, since a molar ratio of 3:1 methanol/oil, converted 66% to biodiesel, being 10% less than the molar ratio of 4:1. Then, it was found that the appropriate amount of enzyme was 2% by mass of enzyme over oil, converting 77%, being that the conversion remained the same with larger values. The time conversion experiment showed that it took 44 hours for a conversion of 78.6%, however, an economic analysis could determine the best time for the reaction. Finally, the equilibrium of phases simulation showed that the more hexane in the system, the higher the concentration of methanol in the oil-containing phase, reducing the conversion because of the inhibitory effect that alcohol has on the enzyme. With tert-butanol, it was found that the lower the amount of cosolvent, the higher the concentration of methanol in the oil-containing phase. Although the system remained in two stages under the tested conditions, the concentration of methanol in the oil-containing phase showed to be high enough to generate good conversions and low enough to not denature the enzyme. The proposed enzymatic process, compared to the alkaline, has advantages in separating and purifying the products, it does not require washing water and neither the use of acid for neutralization, proving to be a cleaner route. In addition, in this case, the separation cycle has lower energy expenditure, with a saving of 233% of cooling water and 34.4% of energy.