Insights into the effect of catalyst loading on methane steam reforming and controlling regime for metallic catalytic monoliths

The influence of Ru/La-Al2O3 catalyst loading (100-200 mg) was investigated over high cell density Fecralloy® monoliths (461 cpsi, 1367 cpsi) for methane steam reforming (MSR). A uniform and well-attached catalyst layer was developed by in-situ washcoating method and the developed catalysts were analyzed by using various physico-chemical characterization techniques. The results confirmed the impact of catalyst loading on the geometric and hydraulic properties of monoliths, and methane conversion was improved by increasing both the catalyst loading and cell density. As per characteristic time analysis, no external and washcoat diffusion regimes were observed and MSR was found to be in kinetic controlling regime. The methane conversion was still limited by the amount of catalyst (200 mg) deposited onto the monoliths (40.9 µm for 461 cpsi, 26.9 µm for 1367 cpsi), which demonstrated the potential to deposit more catalyst up to the transition point of washcoat diffusion limitations. For same washcoat thickness of 20.6 µm, the higher cell density 1367 cpsi monolith showed better catalytic activity towards MSR as compared to 461 CPSI monolith and its improvement is more prominent at lower temperature with a value of 13.6% higher methane conversion at 600 °C, WHSV = 55 NL h–1 gcat–1 and S/C = 3.0.