SiC foam monolith catalyst for pressurized adiabatic methane reforming

Highlights: ► SiC foam support improves coupling reaction of POM and SRM. ► SiC foam based monolithic catalyst shows excellent overall structural stability. ► The dislodgment of active coating lead to the components loss of active coating. ► Ni loss is notably less than Al2O3 loss in active coating. - Abstract: In this work, an Al2O3-coated SiC foam monolith was used as the support of a Ni-based catalyst, which was applied for coupling partial oxidation and steaming reforming of methane to produce syngas or hydrogen. This monolithic catalyst showed excellent structural stability in a 900 h endurance test. Its catalytic activity and stability were also excellent during the first 500 h of the endurance test with a CH4 conversion (∼96%) near thermodynamic equilibrium. Subsequently, it deactivated gradually and its activity was reduced by 7% in the following 400 h. This deactivation is ascribed to deposited carbon that originated from methane cracking in the upper part of the stainless steel reactor. Fresh and used catalyst samples were characterized by XRD, BET, SEM and XRF methods. The results showed that the active coating consisting of Al2O3, and the components loaded on it was partially dislodged from the SiC substrate during the reaction, but the loss of Ni loaded on the Al2O3 coating was less than the loss of Al2O3. This is ascribed to most Ni species being located on the outer surface of the monolithic support, which was more weakly corroded by the reactant flow. The shrinkage of the active coating and the sintering of nickel particles were also observed in the endurance test. Moreover, the SiC foam supported Ni-based monolithic catalyst showed a more homogeneous bed temperature distribution compared with a traditional Ni/Mg–Al spinel catalyst