Natural catalysis-based clean hydrogen production from shale oil: An in-situ conversion enabled by electromagnetic heating

Employing electromagnetic(EM)-assisted catalytic heating to produce hydrogen (H2) directly from petroleum reservoirs is an emerging technology for decarbonizing fossil fuel industry. Transforming hydrocarbons to clean H2 in situ will enable pure hydrogen extraction to surface while simultaneously sequestering carbon underground with the assistance of downhole hydrogen membrane separation technology. Here, we aim to characterize the role of shale rocks in enhancing EM heating and catalyzing shale oil conversion to hydrogen as natural catalysts under EM irradiation. Flow-through experiments are well designed and conducted in a customized microwave reactor system. We also identified for the first time that shale rocks exhibit a “thermal runaway” (TR) phenomenon which occurs at a temperature of 280 °C. After TR happens, the energy needed for heating shale samples to a high enough temperature is significantly reduced under EM irradiation. Further, we identified that metal-rich minerals in shale rocks play an evident natural catalytic effect on shale oil conversion to hydrogen. As a result, hydrogen with a percentage of 1 mol.% starts to be generated at a measured temperature of 253–421 °C in the presence of shale rocks and is a dominant gas in the generated gas products at high temperatures. The highest production rate and concentration of H2 gas are 178 sccm and 77 mol.% from the conversion of 0.4 g of shale oil, respectively. Importantly, CO2 generated during the process is negligible. This work lays a foundation for leveraging the abundant shale rocks and their natural catalytic effect for more efficient, cost-effective, in-situ hydrogen production directly from shale reservoir via the EM-assisted catalytic heating technology we recently proposed.