A compact non-PGM catalytic hollow fibre converter for on-board hydrogen production

Abstract

Hollow fibre-based converters offer an outstanding solution for on-board hydrogen production via ammonia decomposition, representing a more compact, efficient and affordable alternative to traditional packed bed reactors. In this work, Co/Mo-based catalysts supported on three different carbon xerogels were tested during the ammonia decomposition reaction. Co/Mo-NCX, which exhibited the best catalytic performance, was selected to be deposited inside the hollow fibre substrate. At 500 °C and 1 atm the hollow fibre converter was 3.6 times more efficient than the packed bed reactor (i.e. r_NH3 = 5.5 × 10⁴ mol_NH3 m⁻³ h⁻¹ g_cat⁻¹ and r_NH3 = 1.5 × 10⁴ mol_NH3 m⁻³ h⁻¹ g_cat⁻¹, respectively). This can be explained by narrower residence time distribution and minimised mass transfer limitations of the hollow fibre converter. Moreover, the hollow fibre converter showed a noticeably high thermal stability and catalyst-preservability during a 300 h reaction run. Furthermore, it exhibited a significantly lower pressure drop (i.e. >99%), volume (i.e. 70% less) and catalyst loading (i.e. 60% less) compared to the packed bed reactor. On this basis, the hollow fibre converter is especially suitable for on-board hydrogen production in automobiles, where space constraints present a key challenge. The potential of this new technology is enormous, since it will facilitate safe on-board hydrogen production, which is a key step in the decarbonisation of the transport sector in the fuel scenario nowadays.