Selective Hydrogen and Olefins Formation via Microwave Assisted Pyrolysis of Crude Oils Using NiO/Al₂O₃ and NiO/ZSM-5 Catalysts

This research systematically investigated the catalytic pyrolysis of Arab Heavy (AH) and Arab Light (AL) crude oils using NiO supported on Al₂O₃ or ZSM-5 in a microwave-assisted reactor, with particular emphasis on hydrogen (H₂) generation and value-added chemicals. To understand how both the catalyst and feedstock affect reaction products, gas and liquid products as well as catalyst activity were carefully examined. The production of H₂ and olefins was significantly enhanced by the NiO/Al₂O₃ catalyst, especially when using AL crude. This is most likely due to favorable metal-support interactions that increase the dehydrogenation activity. However, when paired with lighter feedstock, NiO/ZSM-5 greatly increased paraffin production and encouraged light alkane synthesis in both phases. GC-MS and FTIR spectroscopy confirmed that NiO/Al₂O₃ produced liquid products richer in aromatics while also containing a significant fraction of paraffins. Remarkably, the AL over NiO/Al₂O₃ combination showed very little liquid recovery, indicating that gas generation was higher in these reaction conditions. These results showed how H₂ selectivity and hydrocarbon routes in NiO/ZSM-5 and NiO/Al₂O₃ are controlled by various microwave-catalyst interactions. This work further highlights the importance of matching catalyst properties with feedstock type to control product selectivity, with NiO/Al₂O₃ showing particular promise for H₂-focused applications.