Publication Date

8-1983

Advisor(s) - Committee Chair

John Reasoner, John Riley, Laurence Boucher

Degree Program

Department of Chemistry

Degree Type

Master of Science

Abstract

The effects of pyrolysis interval, ceiling temperature, heating rate and mesh size on both the pyrolysis yield and relative product distribution for two eastern oil shales (Sunbury and Cleveland) were studied. An extension of the technique of analytical pyrolysis (pyrolysis-gas chromatography) was used. This extension employed a Chemical Data System (C.D.S.) Model 382 Extended Pyroprobe and a C.D.S. Model 310 Concentrator which enabled the pyrolysis products to be collected into a trap system. After completion of a predetermined heating interval, the trap was pulse heated to 250°C and the high and low volatile components were back-flushed into the injection port of a Varian Model 3700 Gas Chromatograph and separated into the low and high molecular weight fractions respectively. Measurements of relative peak areas of the pyrogram gave the yield of the respective fractions.

Samples were repeatedly pulsed to obtain intervals of up to 120 seconds at ceiling temperatures of 750° C for both shales and a cefling temperature of 550°C for the Cleveland shale.

Ceiling temperatures of 550°C, 650°C, and 750°C, with an interval of 20 seconds were investigated for the Sunbury Shale only to test the concentrator system.

Ramps of 10° C/min, 120°C/min, 300°C/min, 100°C/sec, and a nonlinear ramp of 600°C/sec were employed for both the Sunbury and Cleveland shales at a ceiling temperature of 500°C for an interval of 60 minutes. The 10°C/min ramp is a close approximation of the Fischer Assay conditions.

Mesh sizes of -30, 30/60, 60/100, -100 were studied for the Cleveland shale only. Data was collected for each mesh size at a ceiling temperature of 650° C and an interval of 20 seconds.

Carbon-hydrogen-nitrogen and thermogravimetric analyses were also performed on the spent shale. The results of the above investigation may be summarized as follows:

  1. At lower ceiling temperatures, the heating interval has to be increased in order to maintain optimum yields of product.

  2. As the ceiling temperature increases, the overall product yield increases.

  3. There is a shift in product distribution towards the high volatile fraction (lower molecular weights) with higher rates of heating and higher ceiling temperature.

  4. The optimum heating rate for the eastern oil shales studied appears to be between 120° and 300°C per minute.

  5. These experiments suggest that pyrolysis of smaller mesh samples results in a slight yield enhancement. It is also probable that the finer mesh shales are also more susceptible to oxidative aging.

Disciplines

Chemistry | Physical Sciences and Mathematics

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