Valorização da ananas comosus na produção de insumos industriais via pirólise catalítica sobre a zeólita MCM-22

Abstract

The search for sustainable alternatives to fossil fuels has stimulated the valorization of agro-industrial waste through conversion into higher-value chemical products. The abundant and inexpensive peel of Ananas comosus (pineapple) is a promising raw material, but its thermal pyrolysis produces bio-oil rich in oxygenated compounds, giving it undesirable properties. This problem can be overcome by using catalytic pyrolysis, which promotes deoxygenation, cracking, and aromatization, increasing selectivity to target compounds and reducing refining steps. In this context, zeolites stand out as promising catalysts due to their acidity, microporosity, and stability, especially zeolite MCM-22, due to its independent pore system. This study investigated the valorization of pineapple peel and its fractions (cellulose, hemicellulose, and lignin), as well as the extractive-free fraction. Catalytic pyrolysis was performed on desilicated and/or nickel-containing MCM-22 zeolites (3% w/w) to evaluate the influence of these modifications on catalytic activity and selectivity. Nickel reduced the Brønsted to Lewis acid ratio, while desilication produced species more resistant to reduction. Catalytic pyrolysis modifies the product profile compared to thermal pyrolysis, mainly increasing the production of aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylenes (BTEX), followed by a decrease in oxygenated compounds. The use of different biomasses also alters the product distribution profile. Extractive removal increases phenol production, decreases oxygenated compound formation, and virtually eliminates polyaromatic compounds, to a catalyst-dependent extent. The cellulose- and hemicellulose-rich fractions formed mainly oxygenated compounds, BTEX, and phenols, while the lignin-rich fraction predominantly formed BTEX and phenols. The highest BTEX production was observed over the acidic form of the MCM-22-based catalyst during pineapple peel pyrolysis. Modifying the catalysts with nickel or desilication altered the product distribution but did not favor BTEX production. Among these compounds, toluene was the predominant product across all catalysts and biomasses.