Síntese de zeólitas tipo MFI a partir de fontes alternativas de Si e Al: uma abordagem sustentável para a conversão de biomassa em biocombustíveis e químicos renováveis

Abstract

Catalytic pyrolysis has proven to be a promising route for the energy valorization of lignocellulosic residues, such as corn cob residue (CCR). In this study, zeolites with MFI structure were synthesized from alternative sources of silicon and aluminum, such as bentonite, rice husk ash (RHA), and clinoptilolite, using the hydrothermal method with different crystallization times (24 h, 48 h, 72 h, and 7 days). Conventional ZSM-5 zeolite was used as a reference. The synthesized materials were characterized by XRD, XRF, SEM, and BET. The biomass (CCR) was pretreated and characterized by proximate analysis (moisture, volatiles, ash, and fixed carbon), elemental analysis (CHN/O), thermogravimetric analysis (TG/DTG), and calorific value determination. The synthesized zeolites showed a crystalline structure consistent with the MFI pattern, surface areas ranging from 261 to 362 m²/g, and morphology similar to standard ZSM-5. Catalytic analytical pyrolysis was carried out at 500 °C, with product analysis by PyGC/MS. Catalytic pyrolysis using the alternative BC-MFI zeolite (bentonite + RHA) reduced the content of oxygenated compounds by 36% and nitrogenous compounds by 41%, with a 72% increase in aromatic hydrocarbon formation compared to conventional pyrolysis. The results demonstrate that the synthesized zeolites exhibit catalytic performance comparable to that of conventional ZSM-5, with reduced use of standard reagents and greater sustainability, highlighting the potential of waste reuse as precursors for efficient catalysts in the production of biofuels and renewable chemical compounds.