Optimizing the porosity configuration of porous copper fiber sintered felt for methanol steam reforming micro-reactor based on flow distribution

Methanol steam reforming inside micro-reactors is considered as one of the effective approaches for on-board supplying hydrogen for fuel cells. Porous copper fiber sintered felts (PCFSFs) are a new kind of catalyst support for micro-reactors developed in recent years. However, there is a lack of approach to control their porosity configurations due to their random structure. A two-step optimization method was proposed to optimize the PCFSFs' porosity configuration. Firstly, the topology structures of PCFSFs were optimized based on the best flow distributions obtained from macroscopic numerical analyses, and two kinds of PCFSFs with twelve porosity distributions were fabricated through the multi-step mold pressing and solid-phase sintering method. Secondly, the porosity distributions of the semi-optimized PCFSFs were optimized by investigating their reaction characteristics under different gas hourly space velocities (GHSVs) and reaction temperatures. The results indicated that PCFSFs with porosity distribution along the Left-Right direction (PCFSF-LRs) exhibited better reaction performance than PCFSFs with porosity distribution along the Upside-Underside direction (PCFSF-UUs). The methanol conversion and H-2 flow rate for the PCFSF-LRs with porosity distribution of 0.7-0.9-0.8 and 0.8-0.9-0.7 kept on a high level (above 92% and 0.59 mol/h, respectively), regardless of the change of GHSVs and reaction temperatures in most cases. The H-2 selectivity of the PCFSF-LR of 0.7-0.9-0.8 was the highest under large GHSVs and all tested reaction temperatures. The demonstrated effect of counteracting, even reversing the conventional influence of the GHSV and temperature on the performance of methanol steam reforming may be attributed to the more uniform flow distribution in the two PCFSF-LRs.