Statistical and mechanistic analysis of synergetic methanol steam reforming over Ti-based add./Cu-Zn catalysts

This study investigates a commercial Ti-based additive, originally designed for NO x abatement, as a promoter for methanol steam reforming (MSR). When mixed with a Cu-Zn catalyst at 10 wt% (based on the total catalyst mass), the additive achieves 96% methanol conversion and increases the hydrogen yield by ∼ 68%, reaching 2.82 mol∙(mol CH 3 OH) -1 at 250 °C. These outcomes confirm a substantial enhancement in hydrogen production under low-temperature reforming conditions. Operating parameters were evaluated using the Taguchi statistical method, which identifies heating temperature as the primary factor governing hydrogen productivity. Catalyst-bed configuration also plays a critical role. High reforming efficiency is achieved when the methanol feed directly contacts the Ti-based additive, or when the Ti-based additive is homogeneously mixed with the Cu-Zn catalyst. The improved performance is mainly attributed to transition-metal species, particularly Ti, Fe, and Mn, which promote water dissociation and facilitate electronic charge transfer to nearby catalytic sites, thereby supporting the dominant MSR pathway. Long-term operation over 132 h demonstrates that the hybrid catalyst retains approximately 84% of its initial activity. Post-reaction analysis reveals partial carbon deposition on the Cu-Zn catalyst without severe sintering, indicating preservation of active sites. XPS C 1 s analysis shows that carbon species on the Cu-Zn catalyst are mainly present as amorphous C–C type species, whereas such species are minimal on the Ti-based additive. In contrast, the Ti-based additive maintains its mesoporous structure and stable acid-base characteristics. These results demonstrate a durable and effective strategy for low-temperature hydrogen production via MSR.