Production of low-sulfur binder pitch from high-sulfur Illinois coals. Technical report, December 1, 1994--February 28, 1995

The objective of this project is to produce electrode binder pitch with sulfur content below 0.6 wt% from high-sulfur Illinois coal mild gasification liquids. In previous ICCI projects at IGT, flash thermocracking (FTC) was used to successfully upgrade the properties of mild gasification pitch, yielding a suitable blending stock for use as a binder in the production of carbon electrodes for the aluminum industry. However, in pitches from high-sulfur (4%) Illinois coal, the pitch sulfur content is still unacceptably high at 2%. In this project, two approaches to sulfur reduction are being explored in conjunction with FTC: (1) the use of conventionally cleaned coal with low ({approximately}1%) sulfur as a mild gasification feedstock, and (2) direct biodesulfurization of the liquids prior to FTC. In Case 1, the crude pitch is being produced by mild gasification of IBC-109 coal in an existing IGT bench-scale reactor, followed by distillation to isolate the crude pitch. In Case 2, the crude pitch for biodesulfurization was obtained from Illinois No. 6 coal tests conducted in the IGT mild gasification PRU in 1990. Biodesulfurization is to be performed by contacting the pitch with Rhodococcus Rhodochrous IGTS8 biocatalyst. Following preparation of the crude pitches, pitch upgrading experiments are to be conducted in a continuous FTC reactor constructed in previous ICCI-sponsored studies. The finished pitch is then characterized for physical and chemical properties (density, softening point, QI, TI, coking value, and elemental composition), and compared to typical specifications for binder pitches