Production of low-sulfur binder pitch from high-sulfur Illinois coals. Technical report, September 1--November 30, 1994

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 this project, two approaches to sulfur reduction are being explored in conjunction with thermocracking: (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 thermocracking. 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 of the scrubbing solvent and light-to-middle oils to isolate the crude pitch. In Case 2, the crude pitch for biodesulfurization is the same material previously studied, which 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 either as live cultures or in the form of concentrated biocatalyst. Following preparation of the crude pitches, pitch upgrading experiments are to be conducted in a continuous flash thermocracker (FTC) 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. This quarter, 45 kg of IBC-109 coal was obtained and sized to 40 x 80 mesh for mild gasification. Laboratory experiments were conducted to identify means of dispersing or emulsifying pitch in water to render is accessible to biocatalysts, and exploratory desulfurization tests on one-gram pitch samples were begun