Flame Synthesis of Cu/ZnO–CeO₂ Catalysts: Synergistic Metal–Support Interactions Promote CH₃OH Selectivity in CO₂ Hydrogenation

Abstract

The hydrogenation of CO 2 to CH 3 OH is an important reaction for future renewable energy scenarios. Herein, we compare Cu/ZnO, Cu/CeO 2 , and Cu/ZnO–CeO 2 catalysts prepared by flame spray pyrolysis. The Cu loading and support composition were varied to understand the role of Cu–ZnO and Cu–CeO 2 interactions. CeO 2 addition improves Cu dispersion with respect to ZnO, owing to stronger Cu–CeO 2 interactions. The ternary Cu/ZnO–CeO 2 catalysts displayed a substantially higher CH 3 OH selectivity than binary Cu/CeO 2 and Cu/ZnO catalysts. The high CH 3 OH selectivity in comparison with a commercial Cu–ZnO catalyst is also confirmed for Cu/ZnO–CeO 2 catalyst prepared with high Cu loading (∼40 wt %). In situ IR spectroscopy was used to probe metal–support interactions in the reduced catalysts and to gain insight into CO 2 hydrogenation over the Cu–Zn–Ce oxide catalysts. The higher CH 3 OH selectivity can be explained by synergistic Cu–CeO 2 and Cu–ZnO interactions. Cu–ZnO interactions promote CO 2 hydrogenation to CH 3 OH by Zn-decorated Cu active sites. Cu–CeO 2 interactions inhibit the reverse water–gas shift reaction due to a high formate coverage of Cu and a high rate of hydrogenation of the CO intermediate to CH 3 OH. These insights emphasize the potential of fine-tuning metal–support interactions to develop improved Cu-based catalysts for CO 2 hydrogenation to CH 3 OH.

Exploring the Zn-regulated function in Co–Zn catalysts for efficient hydrogenation of ethyl levulinate to γ-valerolactone

“…1d) shows that C, N, Co and Zn elements are uniformly distributed throughout the particles and can overlap in the catalyst, indicating that the prepared material is a homogeneous bimetallic structure. 30,31 The absence of the Zn crystal lattice, consistent with the later XRD result, could be attributed to the low content and ultrafine size, 32 but its existence can be confirmed by EDS, ICP-OES (Table S2†) and XPS analysis (Fig. 2b).…”

Understanding and Application of Strong Metal–Support Interactions in Conversion of CO2 to Methanol: A Review

“…Hensen et al. reported enhanced catalytic activity and CH 3 OH selectivity over a ternary Cu/ZnO/CeO 2 catalyst compared to Cu/ZnO because the Cu/CeO 2 interfaces inhibit the RWGS reaction . In addition, SMSI can be used to improve the stability of catalysts, which is of vital importance in industrial application. , Several papers investigated the reasons for deactivation of the Cu/ZnO system, and structural changes of ZnO are ascribed to the main cause. − The stability of the catalyst can be enhanced by the partial decoration of metal nanoparticles by the support overlayer via the SMSI.…”

“…The difference lies in the facile desorption of CO over Pt/TiO 2 and Pt/SiO 2 catalysts, leading to high selectivity of CO. 142 Hensen et al reported enhanced catalytic activity and CH 3 OH selectivity over a ternary Cu/ZnO/CeO 2 catalyst compared to Cu/ZnO because the Cu/CeO 2 interfaces inhibit the RWGS reaction. 143 In addition, SMSI can be used to improve the stability of catalysts, which is of vital importance in industrial application. 144,145 Several papers investigated the reasons for deactivation of the Cu/ZnO system, and structural changes of ZnO are ascribed to the main cause.…”

Direct catalytic production of dimethyl ether from CO and CO2: A review

“…Nature (Brønsted or Lewis), acid strength (weak to moderate) as well as the textural properties (mesoporosity) of acidic sites play a basic role in the performance of methanol dehydration. Various catalysts for CO2 hydrogenation have been investigated, including [69][70][71][72][73][74][75][76], Pd-based catalysts [77][78][79][80], and bimetallic catalysts such as Pd-Ni, Fe-Ni, Ni-Ti, and Pd-Zn as effective couple for methanol production [81][82][83][84][85]. Among these catalysts, Cu-ZnO-based catalysts are the most widely used [86][87][88][89][90] because the Cu and ZnO loadings play a critical role in the physicochemical properties and catalytic performance of catalysts [91].…”