Cs-Promoted Co Particles on Yttria-Stabilized Zirconia as Coke-Tolerance Methane Dry Reforming Catalyst under Elevated Pressure

Abstract

Methane reforming with CO₂ (dry reforming) co-converts the two green-house gases into synthesis gas and offers a promising way to integrate CO₂ utilization into the current chemical infrastructure. One major obstacle for its industrial deployment is coke deposition on catalyst surface, in particular, under industrially relevant, pressurized operation conditions. Most catalytic investigations are conducted at atmospheric pressure, but the elevation in pressure poses a grand challenge for catalyst design. In this study, we demonstrate that Cs can promote carbon-tolerance of Co catalyst supported on Yttria-stabilized Zirconia under 20 bar, 850 °C with stochiometric feed flow for up to 100 h, which is often regarded as accelerated deactivation testing condition. Lowered amount and mostly CO₂ gasifiable residue carbons are determined in Cs-promoted spent Co-catalyst, with respect to pristine Co catalyst. Kinetic studies reveal that Cs slows down coke deposition, while the essential reaction mechanism on pristine Co catalyst remains unaltered. Cs⁺ moieties absorb CO₂ to afford Cs₂CO₃ that can release O* on adjacent Co surface to facilitate surface C* oxidation and simultaneously suppress carbon nucleation. The disclosure of the promoting effect of Cs on Co catalyst may have implications to other reforming catalyst and process design.