Reduction of CO2 with water splitting hydrogen under subcritical and supercritical hydrothermal conditions

Abstract Hydrothermal conversion of CO 2 into organic chemicals in the presence of Fe and Ni powder under subcritical and supercritical hydrothermal conditions has been carried out, and the results showed that H 2 could be obtained from water splitting under hydrothermal condition. According to Fe 3 O 4 formation, the reaction temperature seemed to influence the generation of H 2 , and H 2 could be formed largely at supercritical condition especially at 425 °C. The formic acid could be produced from CO 2 reduction, and the reaction temperature had a great effect on the formic acid yield. The increase in temperature could improved the formic acid yield, however higher temperature (≥275 °C) seemed to exert a minus influence on the formic acid yield due to decomposition of formic acid. The decomposition of formic acid became quick from 350 °C, and the results showed that the formic acid was decomposed into methane at higher temperature (350 °C).