Advanced fuel processor technology for hydrogen production
Fast and efficient renewable fuel reforming is one of the critical steps in producing hydrogen for fuel cells and the hydrogen economy. Within the EU-funded project BIOROBUR (Biogas robust processing with combined catalytic reformer and trap), scientists successfully developed and tested a robust and efficient decentralised fuel processor based on direct autothermal reforming (ATR) of biogas with no preliminary carbon dioxide separation. The project worked to cover a wide span of potential applications, ranging from fuel cell feed to the production of pure proton exchange membrane-grade hydrogen. The BIOROBUR fuel processor employs ATR using new structured catalysts to convert biogas to hydrogen. These catalyst supports are based on high-thermal-conductivity cellular materials that can efficiently disperse the heat axially in the reactor and are coated with low precious metal content catalysts. What differentiates this process from other similar ones is that heat is directly provided within the reactor through partial oxidation of the biogas. This reduces the need for heat exchangers and increases the plant’s flexibility. Another innovation has been the development of a process for retaining particulate matter emissions in a catalytic wall-flow trap based on transition metal catalysts. Closely coupled to the ATR reformer, this catalytic flow trap can effectively both filtrate and gasify soot particles. These particles are found in the inlet part of the reformer during steady or transient operation or as the product of decomposition traces of incomplete reforming. In more detail, the overall system is split up into three main sections. The first process step comprises compression, preheating, and mixing of air, steam and biogas. After the mixing of steam with air, biogas is supported by a steam ejector that operates with the superheated steam-air mixture. The second block is composed of the catalytic conversion of the mixture to syngas (hydrogen and a carbon oxide mixture) in the ATR unit closely coupled to a wall-flow filter to retain the soot produced. Finally, the gas is purified with high- and low-temperature water gas shift reactors as well as a downstream pressure swing adsorption. The potential for reliable hydrogen production from renewable sources is huge. BIOROBUR’s fuel processor delivering 50 Nm3/h of 99.9 % hydrogen from biogas decreases reliance on fossil fuels, which is an important step to slowing down climate change.
Keywords
Fuel processor, hydrogen production, biogas, BIOROBUR, autothermal reforming
