Conversão térmica e termocatalítica de microalgas utilizando materiais mesoporosos para obtenção de bioprodutos

Abstract

In view of the advancement of the problem caused by pollution to the environment, where the release of greenhouse gases has been growing exponentially, there is a need to implement and improve studies on the topic of clean energies, of renewable origin, in the conversion of biomass. for the production of biofuels. Following this line, the present work aims to evaluate the application of thermal and thermocatalytic conversion of microalgae using mesoporous materials to obtain bioproducts, using Al-MCM-41 impregnated with Cobalt and Molybdenum as catalyst. The catalysts were characterized by X-ray diffraction, X-ray fluorescence and spectroscopy in the infrared region with Fourier transform, observing that there was the formation of a mesoporous material with a one-dimensional hexagonal structure, and at the end of the impregnation steps of the metals, its structure remained organized and composition satisfactory to those found in the literature. Some techniques for characterizing the microalgal biomass were also performed, such as Thermogravimetric Analysis (TGA/DTG) and Fourier Transform Infrared Region Spectroscopy (FTIR), which presented characteristic results in accordance with the literature. Entering the thermal and thermocatalytic study, three microalgae degradation events were observed, which are characteristic events of the process. It is also possible to verify the influence of the catalyst on the degradation of the biomass. The kinetic study came from the Thermogravimetric Analysis (TGA/DTG) of the microalgae with three acetylations, pure and both mixed at a proportion of 90% biomass and 10% catalyst, and then the OFW and KAS kinetic models were applied, with average values of apparent activation energy in between 127.01 - 168.64 and 144,30 - 188.16 kJ mol-1 , respectively. As for the pyrolysis in a fixed bed furnace, the best yields of bio-oil were obtained with the biomass plus 10% of the catalyst, in the presence of molybdenum (Mo/Al-MCM-41), presenting 59.40%, followed by of the catalyst in the presence of cobalt (Co/Al-MCM-41), which obtained 56.98% of bio-oil. According to the GC-MS results, they were also the most selective for compounds of the hydrocarbon class, with 9.09% and 8.33% for the respective catalysts.