Iron-catalyzed pyrolysis converts o-xylene pollutants into graphitic carbon and COx-free hydrogen

Removing volatile organic compounds (VOCs) from emissions is critical, yet current approaches often cause CO 2 emissions or merely transfer VOCs between phases. We present an iron-catalyzed pyrolysis technique that converts o -xylene into solid carbon and COx-free hydrogen, offering the potential to produce COx-free hydrogen from VOCs. Using a high-temperature fixed-bed reactor (800–1000 °C), we found that the reduced Fe catalyst activity increases with temperature and reaction time. Optimal conditions gave a removal capacity of 376.1 mg g −1 , hydrogen production of 394.6 mL g −1 , and carbon production of 268.8 mg g −1 . The decomposition process involves carbon infiltration and the transformation of intermediate Fe 3 C, leading to catalyst fragmentation and enhanced activity. The resulting iron-carbon hybrid features a carbon-encapsulated iron structure comprising crystalline α-Fe and graphite. This structure exhibits superior catalytic performance in degrading methylene blue via H 2 O 2 , offering a promising foundation for developing environmentally friendly VOC treatment technologies.