On-board methanol production using a hollow fibre-based reactor: modelling and experimental validation

Catalytic hollow fibre-based reactors (HFRs) offer a compact, efficient and cost-effective alternative to conventional reactor designs, with strong potential for on-board carbon utilisation. Despite experimental progress, the modelling of coupled transport-reaction phenomena in catalytic HFRs remains limited. This study develops a stepwise modelling framework to examine transport and reaction behaviour in the channel, the catalyst-coated finger and their coupled configuration. Results show that effective reactant delivery requires radial diffusion to be faster than axial advection, establishing a minimum reactor length for sustained conversion. Within the finger, diffusion dominates, leading to the definition of a characteristic finger decay length that provides the basis for a maximum effective finger length for optimal catalyst use. These insights inform the geometric and operational design of a catalytic HFR module for CO 2 hydrogenation to methanol. Experimentally, the HFR enhanced the performance of a Cu-ZnO/ZrO 2 catalyst by a factor of three compared with a fixed bed reactor (FBR), due to intensified reactant–catalyst interaction and improved residence time distribution. The findings provide a quantitative framework for designing compact, high-performance reactors for distributed CO 2 utilisation and other gas-phase catalytic processes.