Preparation of some supported metallic catalysts from metallic cluster carbonyls

J R ANDERSON, P S ELMES, Russell Francis Howe, D E MAINWARING

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Abstract

An examination was made of the adsorption of some metallic cluster carbonyls (MCCs), Co2Rh2(CO)12, Co3Rh(CO)12, Co4(CO)12, Ir4(CO)12, Rh6(CO)16, and Ru3(CO)12, from nonaqueous solution onto two typical catalyst supports, ¿-alumina and Aerosil silica. With two MCCs, Co2Rh2(CO)12 and Ir4(CO)12, dispersed metallic catalysts were generated, and a study was made of how the main experimental conditions affected the metallic dispersion. MCC adsorption was more facile on ¿-alumina than on silica and was often assisted by the presence of oxygen. An ir study showed that initial adsorption of Co2Rh2(CO)12 on ¿-alumina occurred with the loss of bridging carbonyls, the remaining carbonyls being progressively lost at temperatures >300 K, while adsorption of Ir4(CO)2 on ¿-alumina resulted in progressive carbonyl loss at 320–620 K. Strong adsorption involves carbonyl loss, probably by ligand exchange with a surface anion, and the effect of oxygen is probably oxidative decarbonylation. Catalysts prepared from Co2Rh2(CO)12 or Ir4(CO)12 were relatively highly dispersed (D ˜ 0.4-1 depending on conditions), and Co2Rh2(CO)12 gave a much higher dispersion than was obtained by conventional impregnation using aqueous salt solutions. MCC adsorption in the presence of oxygen favored higher dispersions.

Original languageEnglish
Pages (from-to)508-518
Number of pages11
JournalJournal of Catalysis
Volume50
Issue number3
DOIs
Publication statusPublished - Dec 1977

Cite this

Preparation of some supported metallic catalysts from metallic cluster carbonyls. / ANDERSON, J R ; ELMES, P S ; Howe, Russell Francis; MAINWARING, D E .

In: Journal of Catalysis, Vol. 50, No. 3, 12.1977, p. 508-518.

Research output: Contribution to journalArticle

ANDERSON, J R ; ELMES, P S ; Howe, Russell Francis ; MAINWARING, D E . / Preparation of some supported metallic catalysts from metallic cluster carbonyls. In: Journal of Catalysis. 1977 ; Vol. 50, No. 3. pp. 508-518.
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abstract = "An examination was made of the adsorption of some metallic cluster carbonyls (MCCs), Co2Rh2(CO)12, Co3Rh(CO)12, Co4(CO)12, Ir4(CO)12, Rh6(CO)16, and Ru3(CO)12, from nonaqueous solution onto two typical catalyst supports, ¿-alumina and Aerosil silica. With two MCCs, Co2Rh2(CO)12 and Ir4(CO)12, dispersed metallic catalysts were generated, and a study was made of how the main experimental conditions affected the metallic dispersion. MCC adsorption was more facile on ¿-alumina than on silica and was often assisted by the presence of oxygen. An ir study showed that initial adsorption of Co2Rh2(CO)12 on ¿-alumina occurred with the loss of bridging carbonyls, the remaining carbonyls being progressively lost at temperatures >300 K, while adsorption of Ir4(CO)2 on ¿-alumina resulted in progressive carbonyl loss at 320–620 K. Strong adsorption involves carbonyl loss, probably by ligand exchange with a surface anion, and the effect of oxygen is probably oxidative decarbonylation. Catalysts prepared from Co2Rh2(CO)12 or Ir4(CO)12 were relatively highly dispersed (D ˜ 0.4-1 depending on conditions), and Co2Rh2(CO)12 gave a much higher dispersion than was obtained by conventional impregnation using aqueous salt solutions. MCC adsorption in the presence of oxygen favored higher dispersions.",
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AU - ANDERSON, J R

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AU - MAINWARING, D E

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N2 - An examination was made of the adsorption of some metallic cluster carbonyls (MCCs), Co2Rh2(CO)12, Co3Rh(CO)12, Co4(CO)12, Ir4(CO)12, Rh6(CO)16, and Ru3(CO)12, from nonaqueous solution onto two typical catalyst supports, ¿-alumina and Aerosil silica. With two MCCs, Co2Rh2(CO)12 and Ir4(CO)12, dispersed metallic catalysts were generated, and a study was made of how the main experimental conditions affected the metallic dispersion. MCC adsorption was more facile on ¿-alumina than on silica and was often assisted by the presence of oxygen. An ir study showed that initial adsorption of Co2Rh2(CO)12 on ¿-alumina occurred with the loss of bridging carbonyls, the remaining carbonyls being progressively lost at temperatures >300 K, while adsorption of Ir4(CO)2 on ¿-alumina resulted in progressive carbonyl loss at 320–620 K. Strong adsorption involves carbonyl loss, probably by ligand exchange with a surface anion, and the effect of oxygen is probably oxidative decarbonylation. Catalysts prepared from Co2Rh2(CO)12 or Ir4(CO)12 were relatively highly dispersed (D ˜ 0.4-1 depending on conditions), and Co2Rh2(CO)12 gave a much higher dispersion than was obtained by conventional impregnation using aqueous salt solutions. MCC adsorption in the presence of oxygen favored higher dispersions.

AB - An examination was made of the adsorption of some metallic cluster carbonyls (MCCs), Co2Rh2(CO)12, Co3Rh(CO)12, Co4(CO)12, Ir4(CO)12, Rh6(CO)16, and Ru3(CO)12, from nonaqueous solution onto two typical catalyst supports, ¿-alumina and Aerosil silica. With two MCCs, Co2Rh2(CO)12 and Ir4(CO)12, dispersed metallic catalysts were generated, and a study was made of how the main experimental conditions affected the metallic dispersion. MCC adsorption was more facile on ¿-alumina than on silica and was often assisted by the presence of oxygen. An ir study showed that initial adsorption of Co2Rh2(CO)12 on ¿-alumina occurred with the loss of bridging carbonyls, the remaining carbonyls being progressively lost at temperatures >300 K, while adsorption of Ir4(CO)2 on ¿-alumina resulted in progressive carbonyl loss at 320–620 K. Strong adsorption involves carbonyl loss, probably by ligand exchange with a surface anion, and the effect of oxygen is probably oxidative decarbonylation. Catalysts prepared from Co2Rh2(CO)12 or Ir4(CO)12 were relatively highly dispersed (D ˜ 0.4-1 depending on conditions), and Co2Rh2(CO)12 gave a much higher dispersion than was obtained by conventional impregnation using aqueous salt solutions. MCC adsorption in the presence of oxygen favored higher dispersions.

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