Cation promotion effects in zeolite-supported F-T catalysts. Fifth quarterly report, September-November 1984
The ruthenium catalysts under study (Ru/NaY, LiY, KY, CsY, RbY, HY, NaX, KL, NaMordenite), all prepared by ion-exchange, were characterized by selective gas chemisorption at 25/sup 0/C. The hydrogen chemisorption measurements were used to calculate the metal surface area, particle size, and dispersion as described in the 2nd quarterly report. The amounts of irreversibly chemisorbed hydrogen were used in these calculations since this quantity has been shown to best reflect the stoichiometry of H/Ru(s) = 1. However, H/sub 2/ chemisorption alone may not be very reliable for characterization when the metal is highly dispersed on acidic supports such as zeolite-supported ruthenium prepared by ion-exchange. With such supports the suppression of hydrogen chemisorption may be significant. Therefore carbon monoxide chemisorption at 25/sup 0/C was also carried out on the same samples, after desorption of H/sub 2/ at 420/sup 0/C under vacuum. The same procedure as for the H/sub 2/ adsorption measurements was used. CO chemisorption has also been shown to be inadequate for surface area determination, since the stoichiometry of CO adsorption on Ru is determined by the metal particle size. However, CO chemisorption can serve to compare relative metal dispersions and the presence of H/sub 2/ chemisorption suppression since less support effects are evident in CO adsorption. From considerations of CO/H and CO/Ru/sub (total)/ ratios, it is possible to tell whether suppression of hydrogen chemisorption took place on the Ru catalysts.
- Research Organization:
- Pittsburgh Univ., PA (USA). Dept. of Chemical and Petroleum Engineering
- DOE Contract Number:
- FG22-83PC60805
- OSTI ID:
- 6134647
- Report Number(s):
- DOE/PC/60805-T5; ON: DE85004876
- Country of Publication:
- United States
- Language:
- English
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