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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 31, Number 5
BKCSDE 31(5)
May 20, 2010 

 
Title
The Importance of the Aging Time to Prepare Cu/ZnO/Al2O3 Catalyst with
High Surface Area in Methanol Synthesis
Author
Heon Jung, Dae Ryook Yang, Oh Shim Joo, Kwang Deog Jung*
Keywords
Methanol synthesis, Cu/ZnO/Al2O3 catalyst, Malachite, Georgeite, Aging time
Abstract
Ternary Cu/ZnO/Al2O3 catalysts were prepared by a co-precipitation method. The precursor structures were monitored during the aging. The first precipitate structure was amorphous georgeite, which transformed into the unknown crystalline structure. The transition crystalline structure was assigned to the crystalline georgeite, which was suggested with elemental analysis, IR and XRD. The final structure of precursors was malachite. The Cu surface area of the resulting Cu/ZnO/Al2O3 was maximized to be 30.6 m2/g at the aging time of 36 h. The further aging rapidly decreased Cu surface areas of Cu/ZnO/Al2O3. ZnO characteristic peaks in oxide samples almost disappeared after 24 h aging, indicating that ZnO was dispersed in around bulk CuO. TOF of the prepared catalysts of the Cu surface area ranges from 13.0 to 30.6 m2/gcat was to be 2.67 ± 0.27 mmol/m2.h in methanol synthesis at the condition of 250 °C, 50 atm and 12,000 mL/gcat. h irrespective of the XRD and TPR patterns of CuO and ZnO structure in CuO/ZnO/Al2O3. The pH of the precipitate solution during the aging time can be maintained at 7 by CO2 bubbling into the precipitate solution. Then, the decrease of Cu surface area by a long aging time can be prevented and minimize the aging time to get the highest Cu surface area.
Page
1241 - 1246
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