Development of a Ft-Nmr Data Acquisition System and Nmr Studies of Homogeneous Catalytic Processes at High Pressure (Rhodium)
Hoffman, Gregory Alan
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https://hdl.handle.net/2142/70221
Description
Title
Development of a Ft-Nmr Data Acquisition System and Nmr Studies of Homogeneous Catalytic Processes at High Pressure (Rhodium)
Author(s)
Hoffman, Gregory Alan
Issue Date
1983
Department of Study
Chemistry
Discipline
Chemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Chemistry, Analytical
Abstract
This thesis documents the results of the development of a FT-NMR data acquisition and processing system and the development of a high pressure, variable temperature. FT-NMR technique for the study of homogeneous catalytic systems at high pressures.
Since many homogeneous catalytic systems are active only at elevated temperature and pressure, it is usually impossible to perform in situ spectroscopic analysis of the catalytically active species. NMR probes designed to do this are described. Capabilities and limitations are discussed. Gases such as CO, H(,2), and ethylene at pressures up to 2 kbar and temperatures from -50(DEGREES)C to +70(DEGREES)C have been used to study compounds of catalytic interest. Systems discussed are {Rh(,12)(CO)(,30)}('2-), {HRu(,3)(CO)(,11)}('-), and HRh(CO)(PPh(,3))(,3). Resolution is ca. 2-3 Hz using a 5 mm sample. The use of the Redfield 214 pulse sequence for suppression of large signals from the pressurizing gas is described.
The FT-NMR system is based on a distributed processing concept. A ROM-based Z80 S-100 system is used for data acquisition and a LSI-11/02 is used for data processing. The system may be used either in a loosely bound configuration whereby the processors operate independently except for data transfer, or in a tightly bound configuration whereby the LSI-11 completely controls the Z80 functions. The former case is used for normal FT operations while the later case is used for time domain relaxation studies.
The distributed processing concept allows smaller, less expensive computers to be used and simplifies programming by isolating concurrent, time critical operations. This allows each processor to perform more complicated functions.
Appropriate high level compiled languages (Fortran and C) were used for both systems. Options are described which optimizes both ease-of-use and flexibility.
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