Role of macroporosity in macro-mesoporous red mud catalysts for slurry-phase hydrocracking of vacuum residue

• Macro-mesoporous red mud (Ma-RM) was prepared by using PS and F-127 as co-templates.
• The macroporous structure of Ma-RM was connected by the mesopores.
• Ma-RM produced more liquid products in the slurry-phase hydrocracking of VR.
• Ma-RM successfully suppressed coke formation more effectively at higher conversion.
• The catalytic behavior was due to better accessibility to sites in macro-mesopores.

To improve the catalytic performance of red mud (RM) for slurry-phase hydrocracking of vacuum residue, macro-mesoporosity was introduced into RM using polystyrene and Pluronic F-127 as co-templates in this study. The obtained macro-mesoporous red mud (Ma-RM) catalysts were characterized by nitrogen adsorption, X-ray diffraction, ammonia temperature-programmed desorption, scanning electron microscopy, and transition electron microscopy. Subsequently, they were applied to the slurry-phase hydrocracking of vacuum residue at 490 °C for 2 h. Comparative reaction tests revealed that Ma-RM exhibited better catalytic behavior for the VR hydrocracking compared to activated RM without macropores. Ma-RM successfully suppressed coke formation and increased liquid yield in products distribution. The macroporous structure of Ma-RM was connected by mesopores containing active sites for hydrogenation. The presence of a macro-mesoporous structure enhanced hydrogenation over the catalysts due to better accessibility to the active sites for hydrogenation, which induced less coke and more liquid yield.

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