Craqueamento catalítico do óleo de Pachira aquatica Aubl.: uma rota sustentável para a produção de biocombustíveis avançados e Bio-Aditivos

Abstract

Biofuels play a crucial role in the transition to a sustainable energy matrix. Therefore, searching for second- and third-generation biomass sources is important to obtain biofuels. The oil obtained from the seeds of the fruit of Pachira aquatica Aubl. (PAA), also known as Munguba, stands out as a promising raw material to produce biofuels and renewable chemicals of industrial interest, through thermochemical conversion processes. This study aims to develop a drop-in second-generation (2G) biofuel production route through the catalytic pyrolysis of PAA oil. The seeds were collected, characterized, and subjected to mechanical extraction by cold pressing to obtain the oil. This was analyzed to determine ash, density, viscosity, acidity, iodine, saponification, peroxides, and refraction indexes. Fast catalytic pyrolysis of the oil was performed in a Py 5200 micro pyrolyze coupled to GC/MS, varying the temperature of the catalytic bed (300 and 500 °C). The characterization results of the seeds revealed ash (4.05%), moisture (3.09%), and volatile components (91.79%) contents like those presented in the literature, in addition to a high oil yield (36.00%) obtained through a mechanical method. Its composition presents a significant concentration of saturated fatty acids, palmitic (C16:0), followed by unsaturated fatty acids oleic (C18:1) and linoleic (C18:2), with remarkable thermal stability up to 250 °C and high calorific value (37.94 MJ/kcal). The results of conventional analytical pyrolysis of the oil revealed predominance in forming aliphatic hydrocarbons in the C7-C18 range, with low amounts of oxygenated compounds. In the catalytic pyrolysis using HZSM-5 zeolite, a significant reduction in oxygenated compounds was observed, with a predominance of aliphatic hydrocarbons in the C4-C13 range at 500 °C and C7-C14 at 300 °C, with characteristics of drop-in aviation fuels. Based on these data, a 3² factorial design was performed in conjunction with the principal component analysis (PCA) and response surface analysis (RSM) methodology to investigate the effect of the independent variables of catalyst bed temperature (300, 400, and 500 °C) and biomass/catalyst ratio (2, 6 and 12 mg of catalyst) on the response variables, such as hydrocarbon content by the number of carbons in the chains and compound content by biofuel range. The best result was observed when using 2 mg of the catalyst heated to 300 °C, whose product distribution was in the gaps of gasoline (46.5%), diesel (91.2%), kerosene (56.8%), and lubricating oil (54.8%), but due to the overlap of chain sizes for hydrocarbons from different fuel classes, the total sum is higher than 100%. Due to its acidic properties and porous structure, HZSM-5 favored decarbonization, decarbonylation, deoxygenation, and aromatization of pyrolysis products. These results point to the significant potential for the application of PAA seed oil in obtaining advanced biofuels and selectivity to produce renewable aromatics for the chemical industry.