Study on pressurized steam reforming of commercial diesel for solid oxide fuel cell applications

Abstract

Hydrogen sources are increasingly being considered as alternative energy sources because they have great potential for applications in various industrial fields. In particular, because diesel possesses high hydro-gen energy density compared to other fuels, it can be easily used in transportation with solid oxide fuel cells (SOFCs). To utilize diesel for operating SOFCs, diesel reforming technology is necessary. There are three dominant diesel reforming methods: steam reforming (SR), partial oxidation (POX), and autothermal reforming (ATR). In this work, SR is investigated because it has the highest hydrogen production capacity among the reforming methods. In addition, SR is very effective under pressurized environments because it does not require an additional compressor to supply air (using only water as an oxidant). The reactor for diesel SR was pressurized up to 5 bar using a back-pressure regulator. The $CH_4$ concentration dramatically increased according to Le Chatelier’s principle $(CO+3H_2 rightarrow CH_4 + H_2O)$. This increase in $CH_4$ content in the reformate can be used to control thermal management in the SOFC stack. In this work, system modeling was conducted for thermodynamic calculation. Through thermodynamic analysis, proper experimental condition was suggested. And then, experiments were conducted under various conditions to identify the pressure effect on diesel SR. Especially, harsh condition experiment was performed for obvious pressure effect on catalyst. Lastly, case study is progressed. In case study, modeling results and experiment results were considered so as to validate and find the proper condition. Moreover, temperature and pressure effect on catalyst can be analyzed with long term experiment. As a result, the catalytic activity and stability were improved with the kinetic increase from the pressurized reactor.