Carbon-neutral and carbon-negative chemical looping processes using glycerol and methane as feedstock

Carbon-negative and neutral methods to produce H₂ and other syngas-derived chemicals are tested and demonstrated in this study through chemical looping reforming of methane or glycerol. A chemical looping reactor provides the heat required to reform the glycerol or methane while having inherent CO₂ capture. This is achieved using dynamically operated packed beds. If the glycerol or methane is from a biological source this gives the system the potential for negative emissions. To evaluate the potential of this system, 500 g packed bed of oxygen carriers were cyclically reduced, oxidized, and used to carry out reforming experiments. The reforming process was tested at various pressure (1 – 9 bar) and temperature (600 – 900 °C). These conditions were tested at this scale for the first time. Complete conversion of glycerol is achievable with only small quantities of CH₄ slip. The maximum H2 production was achieved at 1 bar and 700 °C producing a H₂/CO ratio of 10, this lowered to 9 when the temperature was increased to 900 °C. Adding CO2 to the feed stream along with H₂O allows for a H₂/CO ratio suitable for the Fischer Tropsch (FT) synthesis. Chemical looping reforming of CH₄ with steam was successfully demonstrated in a lab reactor setup at 1 and 5 bar for multiple cycles with CH₄ conversion > 99% and controlled heat losses. The temperature and concentration profiles provided identical results for consecutive cycles verifying the continuity and the feasibility of the process.