Aspectos fundamentais da pirólise da casca de cacau : análise da cinética do processo e dos efeitos de condições operacionais sobre os produtos

• Autor(a) principal: Coutinho, Brunela Azeredo
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/8466
• topic: Residual biomass; Pyrolysis; Thermogravimetry; Kinetic model; Biomassa residual; Termogravimetria; Modelo cinético; Pirólise; Engenharia/Tecnologia/Gestão; Biomassa; Energia - Fontes alternativas; 620.9

The accelerated population growth experienced today is accompanied by a series of challenges, among them the increase in energy demand. This increased demand generally leads to increased consumption of non-renewable resources and lower levels of water reservoirs responsible for generating energy. It is worth mentioning that reducing the emission of gaseous pollutants is a worldwide concern in the energy sector. Thus, there is a great stimulus for the diversification of the global energy matrix, with a greater presence of renewable sources, such as biomass. In this context, pyrolysis is a technological route for the conversion of residual biomass to products with higher energy content. Thus, a study of cocoa shell pyrolysis (residual biomass) was proposed in this research. In the first stage of this study, the chemical and physical characterization of the biomass through immediate, elemental analysis, X-ray fluorescence and infrared vibrational spectroscopy were performed. In the second stage, the thermal degradation kinetics of the cocoa shell were evaluated through thermogravimetric analyzes, with the aid of kinetic models available in the literature. In addition, the influence of temperature and particle diameter on the yield of the liquid product obtained from the conventional pyrolysis of the cocoa shell in a fixed bed reactor was analyzed. Finally, the characterization of the pyrolytic bio-oil by gas chromatography coupled to a mass spectrometry detector was performed. From the results obtained, it can be concluded that the calorific value, 16.23 MJ / kg, is within the range of being a potential energy source for the production of bio-oil. Also, the pyrolysis of the cocoa shell occurs in two distinct phases, the first one related to the loss of moisture, in the range of 300 to 450 K, and the second one referring to the decomposition of hemicellulose, cellulose and lignin, between 450 and 825 K The activation energy found for cocoa shell through kinetic models is between 125.17 to 134.00 kJ / mol. The particle diameter influenced the yield of the liquid product more than the temperature. The most abundant compounds in the organic fraction of the bio-oil are of the phenols class, considered raw materials of great interest in the chemical and pharmaceutical industry.