Heats of adsorption of oxygen, ethylene, and butadiene on Al sub 2 O sub 3 -supported silver

Journal Article · Fri Mar 01 04:00:00 EST 1991 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(91)90074-E· OSTI ID:5514962

Anderson, K L; Plischke, J K; Vannice, M A ^[1]

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1. Pennsylvania State Univ., University Park (USA)

Heats of adsorption of oxygen on small, clean dispersed Ag crystallites have been measured directly. On the largest (27 nm) Al{sub 2}O{sub 3}-supported particles, the integral Q{sub ad} values of 34-41 kcal mol{sup {minus}1} at 443 K were very consistent with those reported for Ag single crystals, and Q{sub ad} increased to 50 kcal mol{sup {minus}1} on the smallest (3.7 nm) particles. The heats of adsorption measured at 300 K were slightly lower but showed the same trend with crystallite size. The heat of adsorption of ethylene on pure Al{sub 2}O{sub 3} was 10.1 kcal mol{sup {minus}1} at 300 K, which, when combined with the sizable adsorption on the support, precluded any measurement on Ag: however, at 443 K a value of 10 kcal mol{sup {minus}1} could be estimated for C{sub 2}H{sub 4} adsorption on clean Ag because adsorption on the support was significantly reduced. On an oxygen-covered Ag surface, Q{sub ad} values for C{sub 2}H{sub 4} were 5.2 and 64 kcal mol{sup {minus}1} at 300 and 443 K, respectively. Similar measurements for butadiene gave heats of adsorption of 10.9 and 13.1 kcal mol{sup {minus}1} on pure Al{sub 2}O{sub 3} at 300 at 443 K, respectively, and on clean Ag at 443 K, the Q{sub ad} value was 9 kcal mol{sup {minus}1} at 443 K. The nearly identical values at 443 surface. The high values on the latter surface indicate a strong interaction with surface oxygen atoms, presumable involving only a single C{double bond}C bond.

• OSTI ID: 5514962
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 128:1; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020400* -- Petroleum-- Processing
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
ADSORPTION
ADSORPTION HEAT
ALKENES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
BUTADIENE
CATALYST SUPPORTS
CHALCOGENIDES
CHEMICAL BONDS
CRYSTAL STRUCTURE
DIENES
ELEMENTS
ENTHALPY
ETHYLENE
HYDROCARBONS
METALS
NONMETALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POLYENES
SILVER
SORPTION
SORPTIVE PROPERTIES
SURFACE PROPERTIES
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS