Alumina hollow microspheres supported gold catalysts for low-temperature CO oxidation: effect of the pretreatment atmospheres on the catalytic activity and stability

Abstract

Hierarchically organized γ-Al 2 O 3 hollow microspheres were prepared via a hydrothermal method using potassium aluminum sulfate and urea as reactants. The corresponding Au/Al 2 O 3 catalysts were obtained using a deposition-precipitation (DP) method. The effect of the pretreatment under different atmospheres (N 2 , air, and H 2 ) on the activity and stability of the Au/Al 2 O 3 catalysts in CO oxidation was investigated. The results showed that the pretreatment under H 2 atmosphere improved the low-temperature CO oxidation activity. Furthermore, a 50 h long-term test at 30°C showed no significant deactivation for the H 2 -pretreated catalyst. Moreover, the catalytic activity was promoted by H 2 O vapor in all cases, and the H 2 -pretreated catalyst exhibited a good tolerance in the co-presence of CO 2 and H 2 O. Finally, oxygen temperature-programmed desorption (O 2 -TPD) and in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS) revealed that the reductive atmosphere pretreatment greatly improved the CO adsorption capacity and facilitated the oxygen activation.

Promotion effects of nickel-doped Al2O3-nanosheet-supported Au catalysts for CO oxidation

“…In this region, the desorption peak area of the Au/Ni0.05Al-R catalyst was significantly larger than that of Au/Al-R, indicating that the incorporation of Ni remarkably enhanced the capacity for supplying oxygen species. Moreover, for Au/Ni0.05Al-R, new desorption peaks appeared at 80 and 188 °C, arising from surface oxygen species weakly interacting with Au NPs and Ni species, respectively [24,29]. This phenomenon demonstrated that the Au/Ni0.05Al-R adsorbed more active oxygen species and exhibited the strongest ability for utilizing oxygen species of all prepared catalysts, which coincided with catalytic performance and H2-TPR results.…”

“…This indicates that the addition of a suitable amount of nickel can improve the activity of Au/Al for CO oxidation. Because the catalyst pretreatment atmosphere is also known to significantly influence catalytic activity [23,24], the reactivities of the catalysts pretreated under oxidative and reductive atmospheres were investigated (Fig. 1b).…”

Highly dispersed boron-nitride/CuO -supported Au nanoparticles for catalytic CO oxidation at low temperatures

“…Supported-Au catalysts have attracted considerable attention and are generally accepted as the most active catalysts for CO oxidation [1,2]. Many factors can affect the activity of supported-Au catalysts, such as Au particle size, the nature of the support [3,4], and the presence of additional promoters [5][6][7]. Notably, varying the support material can significantly influence the catalytic performance of Au in this reaction system as different support materials exhibit different metal-support interactions [8], oxygen activation abilities [9,10], and even surface functional groups [11].…”

Nanogold supported on manganese oxide doped alumina microspheres as a highly active and selective catalyst for CO oxidation in a H2-rich stream

“…S5 (ESI †), similar vibration bands at 2056, 2114, and 2171 cm À1 were observed for Au/Al, Au/Mn and Au/MnAl catalysts, which can be accordingly ascribed to the CO adsorption on Au dÀ , Au 0 and Au d+ . 11,13 The intensity of peaks at 2056 cm À1 on various Au catalysts follows the order of Au/Al 4 3Au/MnAl 4 Au/MnAl 4 Au/Mn. The results indicate that the increase of the Au content on MnAl support can enhance CO adsorption, thus promoting the catalytic performance for CO-PROX at higher reaction temperatures.…”

“…9 Recently, we have demonstrated a series of Au/Al 2 O 3 catalysts using home-made g-Al 2 O 3 with controlled morphology as efficient supports, which were highly active for CO oxidation, 10 even when CO 2 or/and H 2 O were present at room temperature. 11 Therefore, utilizing the advantages of both manganese and alumina to enhance the catalytic activity and stability appears to be very attractive.…”