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

Abstract

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.