PdZn β alloy catalysts have Cu-like properties for a wide range of industrially important reactions, such as methanol synthesis, water−gas shift, and methanol steam reforming, but overcome the major disadvantages inherited by Cu such as sintering and pyrophoric nature. However, high Pd loadings (e.g., >5.0 wt %) are typically required for the synthesis of the PdZn β alloy, preventing its practical consideration as the replacement of Cu catalysts. Here, we report the synthesis of ZnAl 2 O 4 -supported PdZn β alloy catalysts at extremely low Pd loadings (e.g., 1000 ppm Pd). In particular, a cuboctahedral ZnAl 2 O 4 spinel support with exclusively polar facets provides a strong interaction between Pd and Zn, leading to PdZn β alloy formation even at low Pd loadings. A 0.1 wt % Pd/ZnAl 2 O 4 catalyst is shown to exhibit superior CO 2 selectivity (97%) in the methanol steam reforming reaction, confirming the Cu-like catalytic properties of the PdZn β alloy even at 1000 ppm Pd. The top-layer Zn species on the exposed polar facets of zinc spinel were found to play a critical role in the preferential formation of the PdZn β alloy. The advances toward the PdZn β alloy catalysts with extremely low Pd loadings bring the PdZn alloy catalysts one step closer to a wide range of applications.

The thermocatalytic conversion of hexose into valuable chemicals such as methyl lactate under mild conditions is very appealing. Here, we report that Mo, Mg co-modified Sn-β catalyst can effectively catalyze the transformation of glucose and fructose into alkyl lactate at moderate temperatures. A maximum yield of around 35% of methyl lactate was achieved from the conversion of glucose in methanol at 100°C over Sn-β catalyst modified with 3 wt% Mo and 0.5 wt% Mg. However, up to 82.8% yield of ethyl lactate was obtained in the case of fructose in ethanol upon the same catalytic condition, suggesting a significant solvent effect. The Mo species plays a key role to enable the retro-aldol condensation of fructose, in which the competing side reactions are significantly suppressed with the assistance of neighboring Mg species probably through a synergetic effect of Lewis acid-base.