Vapor pressure isotope effect in /sup 13/CClF/sub 3///sup 12/CClF/sub 3/ by cryogenic distillation kinetics

Technical Report · Fri Aug 01 04:00:00 EDT 1975

DOI:https://doi.org/10.2172/7353315· OSTI ID:7353315

Wieck, H. J.; Ishida, T.

The vapor pressure of /sup 13/CClF/sub 3/ relative to the vapor pressure of /sup 12/CClF/sub 3/ was measured as a function of temperature between 169/sup 0/ and 206/sup 0/K by using a modified Bigeleisen distillation column. The transient build-up of the isotopic concentration gradient along the length of the packed column during the start-up period was monitored by taking samples from the condenser section as a function of time. The gaseous samples were completely oxidized to carbon dioxide in the presence of a platinum catalyst and a large excess of oxygen at temperatures between 1050 and 1100/sup 0/C. The combustion products were purified by means of gas chromatography, and the purified carbon dioxide samples were analyzed in a Nier-type isotope-ratio mass spectrometer. The data of each distillation run were reduced in the light of Cohen's theory of the kinetics of square cascade of close-separation stages. The vapor pressure isotope effect for the carbon substitution in CClF/sub 3/ at temperatures between 169/sup 0/ and 206/sup 0/K was found to be an inverse effect and to be rather insensitive to changes in temperature. The relative vapor pressure may be expressed 1n(P'/P) = ((1.5 +- 14.1)/T/sup 2/) - ((0.159 +- 0.076)/T), or 1n(P'/P) = ((0.173 +- 0.098)/T) - ((0.11 +- 0.53) x 10/sup -3/), where P' and P are the vapor pressures of /sup 12/CClF/sub 3/ and /sup 13/CClF/sub 3/, respectively. To the first-order, the presence of chlorine isotopes would not affect the fractionation of carbon isotopes by the distillation of CClF/sub 3/. (auth)

• Research Organization: Brooklyn Coll., N.Y. (USA)
• Sponsoring Organization: Not Available; US Energy Research and Development Administration (ERDA)
• OSTI ID: 7353315
• Report Number(s): COO-3127-11
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400202* -- Isotope Effects
Isotope Exchange
& Isotope Separation
ALKANES
CARBON 12
CARBON 13
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON ISOTOPES
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CHROMATOGRAPHY
CRYOGENICS
DIAGRAMS
DISTILLATION
EQUATIONS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FLUIDS
GAS CHROMATOGRAPHY
GASES
HYDROCARBONS
INFORMATION
ISOTOPE EFFECTS
ISOTOPES
LIGHT NUCLEI
LOW TEMPERATURE
MASS SPECTROSCOPY
NUCLEI
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SEPARATION PROCESSES
SPECTROSCOPY
STABLE ISOTOPES
TABLES
THERMODYNAMIC PROPERTIES
VAPOR PRESSURE
VERY HIGH TEMPERATURE