Effect of Hydroxyl Groups on Metal Anchoring and Formaldehyde Oxidation Performance of Pt/Al₂O₃

Abstract

Pt/Al 2 O 3 catalysts showing excellent activity and stability have been used in various reactions, including HCHO oxidation. Herein, we prepared Pt−Na/Al 2 O 3 catalysts with a Pt content of 0.05 wt % to reveal the key factors determining the anchoring of Pt as well as the catalytic activity and mechanism of HCHO oxidation. Pt−Na/nano-Al 2 O 3 (denoted as Pt−Na/nAl 2 O 3 ) catalysts with 0.05 wt % Pt content could completely oxidize HCHO to CO 2 at room temperature, which is the lowest Pt content used in HCHO catalytic oxidation to our knowledge. After Na addition, terminal hydroxyl groups (denoted as HO-μ ter ) on nano-Al 2 O 3 were transformed to doubly bridging hydroxyl groups between Na and Al (denoted as HO-μ bri(Na−Al) ), which atomically dispersed Pt species. Pt anchoring further promoted the regeneration of HO-μ bri(Na−Al) by activating O 2 and H 2 O, oxidizing HCHO to CO 2 directly by the fast reaction step (Our study revealed that the HO-μ bri(Na−Al) synergistically generated by HO-μ ter and Na species provided anchoring sites for Pt species.

A simple method to regulate surface hydroxy groups on Al2O3 for improving catalytic oxidation performance for HCHO on Pt/Al2O3

“…3c and d, a new negative band appeared at 3752 cm −1 after doping with Na and Pt species, which was assigned to the doubly bridging OH groups between Na and Al (bri-OH Na–Al groups), replacing the ter-OH groups. 33 As shown in Table S3,† the related contents of bri-OH Na–Al groups of Pt-Na/Al-2h to Pt-Na/Al-5h were 42.5%, 46.4%, 64.6% and 70.2%, respectively, which implied that the related contents of bri-OH Na–Al groups were positively correlated with the calcination duration of the supports. Our work has proved that abundant ter-OH groups turned to bri-OH Na-Al groups after Na species doping, which were beneficial to the dispersion of Pt species.…”

“…Well-dispersed Pt species promoted the activation of O 2 and H 2 O, further generating bri-OH Na–Al groups which showed excellent catalytic ability in HCHO oxidation. 33 As shown in Fig. S7,† there were few bri-OH Na–Al groups on Na/Al-2h because of the lack of ter-OH on Al-2h, while there were abundant bri-OH Na–Al groups on Na/Al-5h, proving that the added Na species and ter-OH groups formed bri-OH Na–Al groups together.…”

“…The result of DFT calculation in our previous work illustrated that Pt single atoms activated H 2 O and O 2 efficiently, forming bri-OH Na–Al groups which were beneficial to HCHO oxidation. 33 Consequently, there was a synergy between Pt atoms and bri-OH Na–Al groups so that bri-OH Na–Al groups provided anchoring sites for Pt atoms, while Pt atoms supplemented bri-OH Na–Al groups by activating H 2 O and O 2 .…”

“…The result of DFT calculation in our previous work illustrated that Pt single atoms activated H 2 O and O 2 efficiently, forming bri-OH Na-Al groups which were beneficial to HCHO oxidation. 33 Consequently, there was a synergy between Pt atoms and bri-…”

Thermal-Driven Optimization of the Strong Metal–Support Interaction of a Platinum–Manganese Oxide Octahedral Molecular Sieve to Promote Toluene Oxidation: Effect of the Interface Pt2+–Ov–Mnδ+

“…Various catalysts, such as transition-metal oxides and supported noble metals, have been developed for the oxidation of VOCs. − Supported Pt-based catalysts have received wide attention due to their outstanding low-temperature activity. − Generally, fine-tuning the strong metal–support interaction (SMSI) is the most considered strategy in the design of supported Pt-based catalysts, which could significantly alter the activity and stability of the catalysts . In 1978, Tauster et al first proposed the concept of SMSIs, which well explained the difference of H 2 adsorption and desorption on precious-metal surfaces, such as Pt, Pd, and Rh .…”