Identification and Insight into the Role of Ultrathin LDH‐Induced Dual‐Interface Sites for Selective Cinnamaldehyde Hydrogenation

Abstract

Focusing on the simultaneous enhancement of activity and selectivity in α, β‐unsaturated aldehyde hydrogenation, we designed and prepared an ultrathin CoAl‐LDH supported Pt catalyst. A series of technologies revealed the ultrathin CoAl‐LDH support possesses the characteristic of dual defects, oxygen vacancy (VO) and cobalt vacancy (VCo). Then, two kinds of vacancy related interface sites were identified, namely Pt−VO−Coδ+ and Pt−VCo−OHδ−. Compared with the bulk catalyst, the ultrathin catalyst exhibits both enhanced intrinsic activity and C=O bond selectivity under the synergistic effect of the dual interface sites. Specifically, the Pt−VO−Coδ+ interface site changes the adsorption mode of cinnamaldehyde and promotes the activation of C=O bonds, thus leading to the improved cinnamyl alcohol selectivity. The H atoms of the Pt−VCo−OHδ− interface site participate in the hydrogenation process, which facilitates the mobility of active hydrogen and therefore promotes the intrinsic activity. More importantly, the ultrathin catalyst shows good reusability.

The Role of Sulfur in the S‐PtRe/Al2O3 Catalysts: The Endogenous Deposition Effect on the Metal/acid Micro‐environment

“…However, compared with the OS catalyst, the peaks of the IS catalyst have a blue‐shift. The relative electron‐deficient state of the IS catalysts can be associated with the newly generated oxygen vacancies, which act as the electron acceptor competitively absorbing the electron [32–34] . This result reveals that the S element introduction approach affects the electronic structure by changing the micro‐environment of the active sites.…”

“…The statistical result illustrates that the highly dispersed PtRe active metals have similar average particle sizes, as shown in Table S2. Therefore, the particle size effect on the catalytic performance can preliminarily be ruled out [32,33] …”

“…Therefore, the particle size effect on the catalytic performance can preliminarily be ruled out. [32,33] Theoretically, the endogenous deposition method includes the steps of atom removal and redispersion, which will significantly change the surface structure of the catalyst. Since acidity is vital for the catalytic performance, the FTIR of pyridine was first employed to identify the effect of the S element addition approach on the acidity of catalysts, shown in Figure S6.…”