Rejuvenation of Pd/Al2O3 with HCl

• Main Authors: Chuen-I Liao, 廖俊一
• Other Authors: Chuin-Tih Yeh
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/97629834278855221980

碩士 === 國立清華大學 === 化學系 === 89 === Different palladium salts were dispersed to alumina, by the incipient wetness method, to prepare samples of 5 %Pd/Al2O3. The dispersion of palladium (DPd) on prepared samples was characterized with hydrogen chemisorption. Measured DPd significantly varied with the precursor of palladium used and the temperature of calcination (Tc). Temperature programmed reduction technique is used to characterize distribution of palladium salts in different environment of calcined samples. A broad peak at Tr = 340 ± 20 K was found in samples prepared with precursor of PdCl2 and is assigned to PdOxCly species strongly interacted with alumina support (Pdi). The intensity of this peak varied with Tc of calcination treatment, i.e., increases with Tc at low Tc temperatures, reached its maximum at Tc =673 K and diminished at elevated Tc. The same trend is found for DPd of samples reduced after the calcination. It is our suggestion that formation of Pdi in calcination plays a key role in preparation of highly dispersed Pd/Al2O3. High DPd was achieved in samples prepared from impregnation of palladium salts dissolved in a concentrated HCl solution. These samples generally exhibit a high Pdi peak in their TPR traces.