Basic evidences for methanol-synthesis catalyst design

A series of Cu–ZnO/ZrO2 catalysts (Znat/Cuat, 0–3; ZrO2, 42–44 wt.%) with markedly improved total (SA, 120–180 m2/g) and metal surface area (MSA, 9–63 m2/g) has been synthesized via the reverse co-precipitation under ultrasound field. Structure, adsorption properties and surface reactivity were probed by BET, XRD, TPR, N2O-titration and TPD measurements of H2, CO and CO2, while the activity pattern in the CO2 to CH3OH hydrogenation reaction (TR, 433–473 K; PR, 1.0 MPa) has been addressed. An optimum ZnO loading (Znat/Cuat, 0.3–0.8) ensures higher process productivity, while the apparent structure sensitive character of the title reaction relies on the synergism of metal hydrogenation and oxide basic sites (dual-site). The extent of the oxide/metal interface, probed by Cuδ+/Cu0 and oxide-to-metal surface area (OSA/MSA) ratios, is the key-parameter allowing the normalization of the catalytic specific activity in a wide range (3–60%) of metal dispersion and the consequent structure insensitive character of the CO2 hydrogenation reaction.