Desenvolvimento integrado de tecnologias de captura e Conversão de CO2: utilização de microalgas, adsorção por zeólitas e conversão catalítica a Dimetil Éter

Abstract

The growth of the population, rapid industrial development, and urbanization have increased the demand for energy production, especially through the use of fossil fuels, resulting in the large-scale release of CO₂ into the atmosphere. It is estimated that fossil fuel power plants emit nearly 33.4 Gt of CO₂ annually, accounting for approximately 40% of the total CO₂ emissions worldwide, significantly contributing to the effects of global warming. In an attempt to mitigate these effects, several efforts have been pursued, including alternative routes for the production of renewable energy such as wind, solar, biomass, and other sources that can minimize CO₂ emissions into the atmosphere, as well as technological routes for carbon dioxide capture—physical, chemical, and biological. The biological route involved the cultivation of Chlorella sp. microalgae in a closed system using 5-liter drum-type flasks and continuous injection of commercial gas containing 98% CO₂, as well as simulated conditions with 15% CO₂, 73% N₂, and 12% O₂. The dry biomass productivity reached 0.81 g/L·day, and the maximum CO₂ fixation rate was 0.90 g/L·day when the microalgae were cultivated with a continuous flow of simulated residual gas and culture medium composed of wastewater. In the sequence of technological pathways aiming at CO₂ mitigation, commercial zeolites CBV 100, CBV 712, CBV 720, CBV 760, and CBV 780 FAU (Y-type) were used in CO₂ adsorption studies. The CBV100Na zeolite proved to be the main CO₂ adsorptive material. CBV100Na and CBV100H showed the highest adsorption capacities: 7.76 mmol/g and 3.92 mmol/g, respectively. Finally, the commercial zeolites were also used as catalytic supports for Cu and Zn impregnation as a catalytic route to promote the conversion of synthesis gas into methanol and/or dimethyl ether. The catalyst CBV720HCuZnCalPR showed the highest selectivity for DME, although with low CO₂ conversion. The catalysts used in this study did not show high selectivity for either DME or methanol; however, the CO₂ conversion ranged from 9 to 56%. Keywords: Microalgae, Chlorella sp, carbon dioxide, catalysis and zeolites.