TY - JOUR
T1 - Structure characterization of WO3/ZrO2 catalysts by Raman spectroscopy
AU - Zhao, Biying
AU - Xu, Xianping
AU - Gao, Jinming
AU - Fu, Qiang
AU - Tang, Youqi
PY - 1996/7
Y1 - 1996/7
N2 - WO3/ZrO2 catalysts prepared by different methods are distinct in their catalytic behaviour. In this work, WO3/ZrO2 catalysts prepared by impregnating Zr(OH)4 and crystallized ZrO2 and then calcining at selected temperatures were characterized by means of qualitative and quantitative Raman spectroscopy. The results showed that ZrO2 in WO3/ZrO2 obtained from crystallized ZrO2 (referred to as WZ) is monoclinic, whereas ZrO2 in WO3/ZrO2 obtained from Zr(OH)4 (referred to as WZH) is in a metastable tetragonal phase as long as the WO3 content is high enough. In both WZ and WZH, WO3 is dispersed on ZrO2 as a monolayer, and the dispersion capacity per 100 m2 of ZrO2 is in good agreement with that estimated from the close-packed monolayer model. However, since the specific surface areas of WZH samples are larger than those of WZ samples, the dispersion capacity per gram of ZrO2 of WZH is larger than that of WZ. A chemical reaction may occur between WO3 and the surface of Zr(OH)4 (or tetragonal ZrO2) at high temperature, and then some superacid sites are created on the surface of the WZH sample.
AB - WO3/ZrO2 catalysts prepared by different methods are distinct in their catalytic behaviour. In this work, WO3/ZrO2 catalysts prepared by impregnating Zr(OH)4 and crystallized ZrO2 and then calcining at selected temperatures were characterized by means of qualitative and quantitative Raman spectroscopy. The results showed that ZrO2 in WO3/ZrO2 obtained from crystallized ZrO2 (referred to as WZ) is monoclinic, whereas ZrO2 in WO3/ZrO2 obtained from Zr(OH)4 (referred to as WZH) is in a metastable tetragonal phase as long as the WO3 content is high enough. In both WZ and WZH, WO3 is dispersed on ZrO2 as a monolayer, and the dispersion capacity per 100 m2 of ZrO2 is in good agreement with that estimated from the close-packed monolayer model. However, since the specific surface areas of WZH samples are larger than those of WZ samples, the dispersion capacity per gram of ZrO2 of WZH is larger than that of WZ. A chemical reaction may occur between WO3 and the surface of Zr(OH)4 (or tetragonal ZrO2) at high temperature, and then some superacid sites are created on the surface of the WZH sample.
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U2 - 10.1002/(SICI)1097-4555(199607)27:7<549::AID-JRS1>3.0.CO;2-9
DO - 10.1002/(SICI)1097-4555(199607)27:7<549::AID-JRS1>3.0.CO;2-9
M3 - Article
AN - SCOPUS:0001020483
SN - 0377-0486
VL - 27
SP - 549
EP - 554
JO - Journal of Raman Spectroscopy
JF - Journal of Raman Spectroscopy
IS - 7
ER -