Catalytic pyrolysis of microalgae using nitrogen-rich algae-based modified biochar for monocyclic aromatic hydrocarbon production

This study proposes a novel and sustainable approach for the catalytic pyrolysis of microalgae to produce monocyclic aromatic hydrocarbons (MAHs) via algae-based modified biochar catalysts with variant porosity and N content. The effects of introducing of different activators (KOH, KHCO3, CH3COOK, K2CO3) on the physicochemical properties and catalytic performance of the catalysts were systematically investigated. The results indicated that the addition of the activators enhances the specific surface area, porosity, and the abundance of O-/N-containing functional groups with catalytic activity in the biochar catalyst, thereby significantly enhancing the performance of catalyst. Among them, SAC-KOH exhibited a superior porous structure and catalytic effect. The modified biochar catalysts markedly promoted MAHs formation, with benzene, toluene, and xylene identified as the major products. With the addition of the SAC-KOH catalyst, the total relative content of benzene, toluene, and xylene can increase from 8.16 % to 36.53 %. Furthermore, to gain deeper insight into the catalytic conversion mechanism of microalgae to MAHs using modified biochar catalysts, the product transition pathway was explored in depth and comprehensively with soybean protein, sucrose, and peanut oil as the main model compounds of microalgae. These findings demonstrate the feasibility and effectiveness of modified biochar catalysts in enhancing MAHs production from microalgae, providing a promising strategy for aromatic generation.