Physical and Chemical Synthesis of Au/CeO2 Nanoparticle Catalysts for Room Temperature CO Oxidation: A Comparative Study

Abstract

In many heterogeneous catalytic reactions, such as low-temperature CO oxidation, the preparation conditions, and the role of the CeO2 support (oxygen vacancies and redox properties) in the dispersion and the chemical state of Au, are considered critical factors for obtaining gold nanoparticle catalysts with high catalytic performance. In this work, the physical and chemical preparation methods were compared, aiming at understanding how the preparation method influences the catalytic activity. The Au/CeO2 nanoparticle catalysts with 5% Au loading were prepared via the Physical Laser Vaporization Controlled Condensation method (LVCC), and the chemical Deposition-Precipitation method (DP) was used to investigate the effect of synthesis methods on the structure and the catalytic activity toward the CO oxidation. In this manuscript, we compare the activity of nanostructured Au/CeO2 catalysts. The structure and the redox properties of the catalysts were investigated by the XRD, SEM, TEM, TPR, and XPS. The catalytic activity for low-temperature CO oxidation was studied using a custom-built quartz tube flow reactor coupled with an infrared detector system at atmospheric pressure. The study reveals that the prepared CeO2-supported Au nanoparticles’ catalytic activity was highly dependent on the preparation methods. It showed that the sample prepared by the DP method exhibits higher catalytic efficiency toward CO oxidation when compared with the sample prepared by the LVCC method. The high catalytic activity could be attributed to the small particle size and shape, slightly higher Au concentration at the surface, surface-active Au species such as Au1+, along with the large interface between Au and CeO2. This study suggests that the stability, dispersion of Au nanoparticles on CeO2, and strong interaction between Au and CeO2 lead to strong oxidation ability even below room temperature. Considering the universal character of different physical and chemical methods for Au/CeO2 preparation, this study may also provide a base for supported Au-based catalysts for many oxidation reactions in energy and environmental applications.

High-efficiency reduction of p-nitrophenol on green-synthesized gold nanoparticles decorated on ceria nanorods

“…31 But, because of the extremely low gold loading (only 0.3 wt%), the gold diffraction peaks are not clearly dened, which is also consistent with previous reports. 31,32 The small Au particles estimated by the Debye-Scherrer equation 33,34 with sizes of around 1 nm are considered to be below the XRD detection limit, 32 which suggests that Au nanoparticles were well dispersed on the surface as well as in the internal structure of the CeO 2 nanorods. 35 The XRD results also showed no interaction between AuNPs and CeO 2 to form a new phase.…”

Microreactor Based on Trimetallic Nano-Oxides Obtained by In Situ Growth from German Silver

“…Carbon monoxide is a common contaminant of hydrogen streams that poisons platinum-based catalysts of PEMFC type fuel cells [4]. For the CO oxidation reaction, catalysts based on noble metals such as Au, Pt, and Pd have traditionally been used [5][6][7], although among them, the most widely used systems have been those based on supported gold such as Au/ZnO-ZrO 2 , Au/CeO 2 , or Au/Co 3 O 4 -CeO 2 [8][9][10]. However, as mentioned above, the search for noble metals-free catalysts in recent years has led to the development of systems based on mono-and multi-metallic oxides.…”

Promotion of Low‐Temperature Oxidation of Propane through Introduction of Ce into Mullite Oxide YMn2O5

“…The unique property of ceria provides more active lattice oxygen, increases the dispersion of the loaded metal and prevents sintering or coke formation. [25,26] Saoud et al [27] dispersed gold nanoparticles on CeO 2 and found that strong interaction between Au and CeO 2 leads to high CO oxidation ability even below room temperature. Lee et al [28] constructed a Rh-doped CeO 2 catalyst, which exhibited a remarkable soot oxidation activity owning to abundant surface oxygen vacancies and efficient electron transfer.…”