(391b) Hydrogen Production from Syngas Using Metal Oxide Composite Particles

Hydrogen is commonly produced by steam reforming of methane. During steam reforming of methane, the methane molecule decomposes to produce synthesis gas, which mainly contains CO and H2. The synthesis gas is then reacted with steam to further produce hydrogen using the water gas shift (WGS) reaction. The WGS reaction is performed in two stages and is highly sulfur sensitive. Thus, the synthesis gas has to be purified before entering the catalytic bed. The product gas stream exiting from the WGS reactors contain a mixture of H2 and CO and CO2. Hydrogen is then separated from CO2 and CO and further cleaned when H2 is needed for use in fuel cells. The hydrogen separation from CO2 and CO is costly and capital intensive. Therefore, a process which avoids these separation and purification steps is highly desirable. In this study, a novel process is developed to produce H2 from synthesis gas at high temperatures with integrated high pressure CO2 production. This process involves two steps of operation: 1) syngas oxidation and 2) H2 production. In the syngas oxidation stage, the synthesis gas reacts with a metal oxide producing CO2 and H2O, which, after the isobaric water condensation, gives a sequestrable CO2 stream. During the syngas oxidation, the metal oxide is reduced to its metallic form. The reduced metal is then reacted with steam to generate hydrogen and regenerate the metal oxide. This process has many advantages for the production of hydrogen from syngas compared to the WGS reactions: 1) it is carried out at higher temperatures and no temperature swing is needed, 2) a sequestrable CO2 stream is produced by design, 3) higher synthesis gas utilization and hydrogen production rates are obtained. This process is also readily extendible to coal and biomass gasification applications. Composites metal oxide particles have been developed that are resisting to sintering and mechanical degradation. These particles were tested under simulated syngas environment. It was found that these particles retain their activity over multiple redox cycles with high conversions and possess a high potential for hydrogen production from synthesis gas.