TY - JOUR
T1 - A comparative investigation on the properties of Cr-SBA-15 and CrOx/SBA-15
AU - Zhang, Lei
AU - Zhao, Yanhui
AU - Dai, Hongxing
AU - He, Hong
AU - Au, C. T.
N1 - Funding Information:
The work described above was supported by the National Natural Science Foundation of China (Grant No. 20473006) and Funding Project for Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality (PHR (IHLB)).
PY - 2008/2/29
Y1 - 2008/2/29
N2 - High-surface area and well-ordered mesoporous Cr-incorporated SBA-15 (Cr-SBA-15) and SBA-15-supported chromia (CrOx/SBA-15) with Cr surface density = 0.05-1.11 Cr-atom/nm2 have been prepared, respectively, using the one-step synthesis and incipient wetness impregnation method, and characterized by AAS, XRD, BET, ESEM, TEM, XPS, laser Raman, UV-Vis, FT-IR, and H2-TPR. It is observed that the Cr-SBA-15 and CrOx/SBA-15 samples showed an evolution of surface morphology from long chain-shaped to short rod-like and further to an irregularly spherical architecture at elevated Cr content, which might arise from the interaction of Cr ions or CrOx domains with SBA-15. There were co-presence of tetrahedrally coordinated mono- and poly-chromate (Cr6+) as well as octahedrally coordinated Cr3+ species in Cr-SBA-15 and CrOx/SBA-15, with the Cr6+ species being dominant at Cr surface density ≤0.22 Cr-atom/nm2 in Cr-SBA-15 and Cr ≤0.54 Cr-atom/nm2 in CrOx/SBA-15, whereas the amount of the Cr3+ species increased markedly at Cr surface density ≥0.53 Cr-atom/nm2 due to the formation of crystal Cr2O3 phase. Maximal Cr incorporation into Cr-SBA-15 and one monolayer surface CrOx coverage on CrOx/SBA-15 occurred at Cr surface density ≤0.53 Cr-atom/nm2 and <1.11 Cr-atom/nm2, respectively. The CrOx/SBA-15 samples exhibited better reducibility than the Cr-SBA-15 samples, with the best reducibility exhibited at Cr surface densities of 0.54 and 0.12 Cr-atom/nm2, respectively.
AB - High-surface area and well-ordered mesoporous Cr-incorporated SBA-15 (Cr-SBA-15) and SBA-15-supported chromia (CrOx/SBA-15) with Cr surface density = 0.05-1.11 Cr-atom/nm2 have been prepared, respectively, using the one-step synthesis and incipient wetness impregnation method, and characterized by AAS, XRD, BET, ESEM, TEM, XPS, laser Raman, UV-Vis, FT-IR, and H2-TPR. It is observed that the Cr-SBA-15 and CrOx/SBA-15 samples showed an evolution of surface morphology from long chain-shaped to short rod-like and further to an irregularly spherical architecture at elevated Cr content, which might arise from the interaction of Cr ions or CrOx domains with SBA-15. There were co-presence of tetrahedrally coordinated mono- and poly-chromate (Cr6+) as well as octahedrally coordinated Cr3+ species in Cr-SBA-15 and CrOx/SBA-15, with the Cr6+ species being dominant at Cr surface density ≤0.22 Cr-atom/nm2 in Cr-SBA-15 and Cr ≤0.54 Cr-atom/nm2 in CrOx/SBA-15, whereas the amount of the Cr3+ species increased markedly at Cr surface density ≥0.53 Cr-atom/nm2 due to the formation of crystal Cr2O3 phase. Maximal Cr incorporation into Cr-SBA-15 and one monolayer surface CrOx coverage on CrOx/SBA-15 occurred at Cr surface density ≤0.53 Cr-atom/nm2 and <1.11 Cr-atom/nm2, respectively. The CrOx/SBA-15 samples exhibited better reducibility than the Cr-SBA-15 samples, with the best reducibility exhibited at Cr surface densities of 0.54 and 0.12 Cr-atom/nm2, respectively.
KW - Chromium-incorporated SBA-15
KW - Mesoporous silica SBA-15
KW - Reducibility
KW - SBA-15-supported chromia
KW - Surface chromia species
KW - Surface morphology
UR - http://www.scopus.com/inward/record.url?scp=38349176942&partnerID=8YFLogxK
U2 - 10.1016/j.cattod.2007.10.017
DO - 10.1016/j.cattod.2007.10.017
M3 - Journal article
AN - SCOPUS:38349176942
SN - 0920-5861
VL - 131
SP - 42
EP - 54
JO - Catalysis Today
JF - Catalysis Today
IS - 1-4
ER -