Deactivating and Non-Deactivating Coking Found on Ni-Based Catalysts during Combined Steam-Dry Reforming of Methane

Abstract

Management of coke formation during the dry reforming (DRM) and combined steam reforming (CSDRM) of methane is a crucial key towards the control of catalyst performance of such processes. Hence, this work provided a fundamental understanding of coke and coking to achieve the desire performance for the Ni-based catalysts typically employed in the industrial via the control over the formation of deactivating coke – amorphous (Cβ), carbide (Cγ), and graphitic coke (CC) that associated directly to the catalyst performance. Therefore, it is demonstrated that during DRM and CSDRM, a low reaction temperature would result in a conversion that is too low to be a practical process, while around 600 °C, the Ni carbide (Cγ) would form in high quantity, and operating up to 800 °C will cause the catalyst performance to drop significantly due high amount of graphitic coke. The CSDRM process compared to DRM can reduce the deactivating coke from 25 – 38% to 2.5 – 21.4% on the Ni-based catalysts. This positive effect on coke-resistant is the elimination of Cβ formation, which is the reactant for the graphitic carbon formation, resulting in a decrease in the overall amount of deactivating coke. Hence, we suggested that one select CSDRM over DRM due to the promotional effect of steam associated with the mitigation of the total deactivating coke via the blocking of amorphous coke formation and the appropriate temperature prevent Cγ and CC formation.