Electron spin resonance and electron spin echo spectroscopic studies of paramagnetic rhodium species produced in RhCa-X zeolite during ethylene dimerization: Evidence for a. sigma. -bonded intermediate

Journal Article · Thu Feb 22 04:00:00 EST 1990 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100367a052· OSTI ID:6947406

Bass, J S; Kevan, L ^[1]

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1. Univ. of Houston, TX (USA)

Electron spin resonance (ESR) and electron spin echo modulation (ESEM) spectroscopies were used to characterize paramagnetic active sites formed in RhCa-X zeolite during ethylene dimerization and the structure of a key reaction intermediate for the first time. Adsorption of ethylene at 195 K onto RhCa-X activated in flowing O{sub 2} at {approx} 673 or {approx} 773 K produced two new Rh(II) ESR signals, E1 and E2, which decay as a function of time. The rate of decay in samples activated at {approx} 673 K is faster compared to the decay in samples activated at {approx} 773 K, and this correlates with the percent ethylene conversion observed after 18-20 h at 296 K under static reaction conditions. Species E2 formed with deuterated ethylene could be analyzed by ESEM to give the number and distance of the nearest deuteriums. On the basis of the available data, a suggested reaction mechanism is proposed in which the reaction proceeds by a mechanism similar to that for dimerization by a homogeneous RhCl{sub 3} catalyst.

• OSTI ID: 6947406
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 94:4; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKENES
CALCULATION METHODS
COMPLEXES
DATA
DATA ANALYSIS
ELECTRON SPIN RESONANCE
ETHYLENE
EXPERIMENTAL DATA
HYDROCARBONS
INFORMATION
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
MAGNETIC RESONANCE
MATERIALS
MEASURING INSTRUMENTS
MEASURING METHODS
MINERALS
NUMERICAL DATA
ORGANIC COMPOUNDS
RESONANCE
RHODIUM COMPLEXES
TRANSITION ELEMENT COMPLEXES
ZEOLITES