Unmixed Reforming for the Production of Hydrogen from Biomass and Waste
4 September 2006
Researchers at the University of Leeds (UK) have received a £344,835 (US$657,228) grant from the engineering and Physical Sciences Research Council to further the development of the process of unmixed reforming for the production of hydrogen from biomass and waste.
Unmixed reforming is an autothermal process—it derives its heat from the cyclic oxidation of a nickel-based catalyst. The heat is used to reform the feedstock—sunflower oil in some of the group’s earlier work—with steam to produce hydrogen. A CO2 adsorbent material takes up excess carbon dioxide for subsequent storage or production in other chemical processes. When using a suitable CO2 sorbent in the reformer, the team found that the dry hydrogen content in the reformate gas reached above 80%.
The process operates in a two-phase cycle, switching from airflow to the fuel/stream mixture. Because production of hydrogen from one reactor is thus intermittent, the continuous production of hydrogen requires at least two identical packed bed reactors running in parallel, each on a different half-cycle.
The effluent gas of the fuel/steam step is much higher in hydrogen than the single reactor equivalent conventional process, and the oxidized catalyst is regenerated by reduction from exposure to the fuel. Furthermore, in the unmixed steam reforming process, sulfur in the fuel also undergo oxidation under the airflow rather than irreversibly poisoning the reforming catalyst.
The process promises to be economical at a small scale, and could be used in a distributed scenario for hydrogen production—at the filling station, for example.
This current grant project, led by Dr. Valerie DuPont, is a follow-on to earlier work funded by EPSRC and seeks to improve on the original process. The researchers, led by Dr. Valerie DuPont, are working with Johnson Matthey on the identification and refinement of the catalysts.
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