ZnAl₂O₄ Spinel-Supported PdZn_β Catalyst with Parts per Million Pd for Methanol Steam Reforming

Abstract

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.

Catalytic hydrogen storage in liquid hydrogen carriers

“…Wang et al studied the effect of Pd loading (0.1 to 15 wt%) of Pd/ZnAl 2 O 4 in MSR. 220 Characterization results show that α-PdZn alloy phase forms on the catalyst with high Pd contents of ≥7.5 wt%, while β-PdZn alloy phase forms on the catalysts with low Pd content of ≤2.5 wt%. The Pd loading has a significant influence on CO 2 selectivity.…”

Recent Progress in Application of Propargylic Alcohols in Organic Syntheses

“…In 2023, Wang′s research team developed an interesting three‐segment reaction between β ‐substituted α ‐naphthyl propargylic alcohols 192 , aryl iodides 193 and benzyl chlorides 194 via a cross‐electrophile strategy (Scheme 83). [78] Diversely axially chiral allylic alcohols 195 containing a tetrasubstituted olefinic moiety were synthesized in the presence of a nickel catalyst in this protocol. In the next phase, the conversion of the OH group into many functional groups, such as acid, aldehyde, amine, azide, etc.…”

High-Stability ZnAl2O4 Spinel-Supported Nickel Catalyst for High-Temperature Syngas Methanation

“…In previous work, we synthesized supported PdZn catalysts using a ZnAl 2 O 4 spinel as a support to provide atomic-level control of the zinc source for the formation of PdZn alloy, thanks to the unique spinel structure and the strong interaction between the metal and the support. The advanced Pd/ZnAl 2 O 4 catalysts show superior activity and stability toward Syngas conversion and methanol-steam-reforming reaction, even upon ppm Pd loading. , Herein, we came up with a novel design to synthesize a ZnAl 2 O 4 -supported/dispersed Ni metal catalyst, where the zinc aluminate spinel featuring superior thermal and hydrothermal stability is employed to support and disperse the active Ni component. The obtained Ni/ZnAl 2 O 4 demonstrated comparable reactivity but better stability during the methanation test conducted above 450 °C, compared with the Ni/Al 2 O 3 counterparts.…”

“…The advanced Pd/ZnAl 2 O 4 catalysts show superior activity and stability toward Syngas conversion and methanol-steam-reforming reaction, even upon ppm Pd loading. 31,32 2.3. Characterization Methods.…”