Valorização energética via pirólise catalítica de resíduos da extração de taninos de Anacardium occidentale L.

Abstract

The growing demand for sustainable energy has intensified interest in the energy conversion of lignocellulosic by-products, such as those generated during the extraction of tannins from cashew trees (Anacardium occidentale L.). This study evaluated the energy potential of these by-products through catalytic flash pyrolysis, aiming to maximize efficiency and enhance properties, thereby increasing the value of the products within the process. The physicochemical characterization of the biomass was performed using proximate, ultimate, biochemical composition, and thermogravimetric (TGA) analyses, along with flash pyrolysis at 500°C in a micro-pyrolyzer coupled to a gas chromatograph and mass spectrometer (Py GC/MS). The impact of different catalysts (HZSM-5, also known as acidic zeolite, eggshell, and activated carbon) on product composition was evaluated. The results indicate a high volatile matter content (76.34%), favoring the release of energy compounds during thermal processes, while the low ash content (1.75%) reduces inert residues, improving the efficiency and technical feasibility of energy conversion. The HZSM-5 catalyst stood out for its production of aromatic hydrocarbons (95.91%), high deoxygenation efficiency (4.09%), and complete elimination of nitrogen compounds. Conversely, eggshell and activated carbon demonstrated potential for deoxygenation and hydrocarbon production but showed limitations in denitrogenation. These catalysts appear more suitable for applications prioritizing oxygen removal and have potential for optimization through chemical treatments to enhance their catalytic efficiency and expand their applicability. The results confirm the potential of tannin extraction by-products as a renewable and sustainable source of bioenergy, with properties comparable to other lignocellulosic biomasses already used in the energy sector.