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1703190 
Journal Article 
Comparative study by infrared spectroscopy and microcalorimetry of the CO adsorption over supported palladium catalysts 
Guerrero-Ruiz, A; Yang, SW; Xin, Q; Maroto-Valiente, A; Benito-Gonzalez, M; Rodriguez-Ramos, I 
2000 
1 
Langmuir
ISSN: 0743-7463
EISSN: 1520-5827 
16 
21 
8100-8106 
WOS:000089799900032 
The adsorption of CO on Al(2)O(3), ZrO(2), ZrO(2)-SiO(2), and ZrO(2)-La(2)O(3) supported Pd catalysts was studied by adsorption microcalorimetry and infrared (TR) spectroscopy. Some interesting and new correlations between the results of microcalorimetry and IR spectroscopy have been found. The CO is adsorbed on palladium catalysts in three different modes: multibonded (3-fold), bridged (2-fold), both on Pd(lll) and (100) planes, and linear (1-fold) adsorbed species. The corresponding differential adsorption heats lie in the field of high (210-170 kJ/mol), medium (140-120 kJ/mol), and low (95-60 kJ/mol) values, respectively. The nature of the support, the reduction temperature, and the pretreatment conditions affect the surface structure of the Pd catalysts, resulting in variations in the site energy distribution, i.e., changes in the fraction of sites adsorbing CO with specific heats of adsorption. Moreover, the CeO(2); promoter addition weakens the adsorption strength of CO on palladium. Based on the exposed results, a correctness factor, which considers the percentages of various CO adsorption states, must be introduced when one calculates the Pd dispersion using CO adsorption data.