Role of zeolite framework and acidity in Cu-based catalysts for dimethyl ether steam reforming

Four commercial zeolites (denoted as HFER (Si/Al = 10), HY‑1 (Si/Al = 40), HY‑2 (Si/Al =2.6) and HZSM‑5 (Si/Al = 45) were evaluated at 400 and 500 ºC. NH3‑TPD showed differences in total acidity, from 1.25 mmol NH3/g in HFER to 0.16 mmol NH3/g in HY‑1. Among the catalysts that follow the steam reforming pathway, Cu/HY‑2 reached the highest DME conversion (95.2% at 500 ºC), whereas Cu/HY‑1 reached the highest hydrogen yield (up to 43.3 % at 500 ºC), highlighting the importance of moderate acid strength and well-dispersed Cu0 particles.

In contrast, Cu/HFER showed limited H2 production due to its strong acidity, narrow channels and large Cu0 crystallites (48.9 nm). Although Cu/HZSM‑5 achieved complete DME conversion, the reaction proceeded through hydrocarbon‑forming routes rather than DME‑SR, leading to negligible hydrogen formation. Overall, the results highlight the combined influence of zeolite framework, acidity and metal dispersion on DME‑SR performance.