Isotopic exchange between 2,2-dimethylbutane and deuterium on rhodium/silica gel catalysts

Journal Article · Sat Feb 01 04:00:00 EST 1992 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1016/0021-9517(92)90240-I· OSTI ID:7079700

Takehara, D K; Butt, J B; Burwell, Jr, R L ^[1]

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1. Northwestern Univ., Evanston, IL (United States)

Isotropic exchange between 2.2-dimethylbutane and deuterium has been investigated at 75 C on 10 rhodium on wide-pore silica gel catalysts with H(chemisorbed)/Rh(D{sub h}) ranging from 11 to 108% and subjected to a variety of pretreatment conditions. Some catalysts were prepared by ion exchange with Rh(NH{sub 3}){sub 5}(H{sub 2}O){sup 3-} and some by impregnation to incipient wetness with Rh{sub 4}(CO){sub 12} or Rh{sub 6}(CO){sub 16}. The turnover frequency (N{sub t}) is affected both by D{sub h} and by the conditions of pretreatment. The extreme variation was a factor of 330. Exchange into the ethyl group was about 10 times faster than into the t-butyl group. In general, the catalysts of largest D{sub h} gave the largest N{sub t} and the smallest degree of multiple exchange in the ethyl group. The pretreatment, H{sub 2}, 450 C gave the largest N{sub t}. Mere removal of H* from catalysts so treated by He, 300 C had little effect, but He, 450 C led to a substantial decrease in N{sub t} except for 11-Rh/SiO{sub 2}. The various coupled values of N{sub t} and selectivity resulting from variations in D{sub h} and pretreatment require a minimum of eight different sites. N{sub t}'s and selectivities in the hydrogenolysis of methylcyclopropane on these same catalysts parallel those in the exchange of neohexane.

• OSTI ID: 7079700
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 133:2; 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
400202* -- Isotope Effects
Isotope Exchange
& Isotope Separation
ADSORBENTS
ALKANES
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CYCLOALKANES
DEHYDROGENATION
DEUTERATION
DEUTERIUM
DIAGNOSTIC TECHNIQUES
ELEMENTS
FLUIDS
GASES
HELIUM
HYDROCARBONS
HYDROGEN
HYDROGEN ISOTOPES
IMPREGNATION
ION EXCHANGE
ISOTOPES
ISOTOPIC EXCHANGE
LIGHT NUCLEI
METALS
NONMETALS
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PLATINUM METALS
PRECURSOR
RARE GASES
RHODIUM
SILICA GEL
STABLE ISOTOPES
SYNTHESIS
TRANSITION ELEMENTS