(561a) Modal Switching for Continuous Solar Reforming

The carbon footprint of methane reforming processes can be reduced by using solar thermal energy in place of fossil energy for process heating. In this scheme, concentrated solar power provides heat that drives endothermic reformation of methane, storing renewable energy in the chemical bonds of the resultant synthesis gas. CO₂ can be directly valorized in this process to further offset end-use carbon emissions. However, solar transience hinders the operational window and overall efficiency of these systems, limiting their practical feasibility. Here predictive switching between bi-reforming and tri-reforming of methane modes over a single nickel-based catalyst is applied in order to operate solar methane reforming continuously. This is performed using Oregon State University’s solar simulator and directly-irradiated volumetric reactor, which is designed to promote fast transient behavior of solar-thermochemical reactions. Solar-to-chemical efficiency is calculated over periods of transient modal switching, where solar power is reduced incrementally and oxygen with additional methane are throttled into the feed to compensate for this decrease in external heating. Catalyst stability and coke formation are examined after modal switching.