Yunsong Tong

Degree Name

Master of Science (MS)

Semester of Degree Completion

1993

Thesis Director

David H. Buchanan

Abstract

Organic sulfur compounds in coal should be removed as completely as possible in order to make coal "clean" during its usage. Before any method for coal desulfurization can be investigated, the structure of coal should be known. Soluble substances in coal are more easily analyzed by spectroscopic methods than is the insoluble coal. The goal of this research is to separate soluble organic sulfur compounds from the original coal by pyridine extraction. The weight percentages of the coal extracts obtained from three different coal samples by single step extractions ranged from 8% to 30%. The coal extractability could also be enhanced by acid demineralization, lithium aluminum hydride (LAH) reduction, and ultrasonic treatment.

Because there might be some soluble sulfur compounds hidden in the blocked pores of coal which are difficult to remove by normal solvent extraction, hydrochloric acid and hydrofluoric acid were used to dissolve minerals in coal which could trap potential soluble compounds including organic sulfur. After one or more pyridine extractions, LAH was introduced to react with iron pyrites (FeS2) in the coal residue to allow the pyridine solvent to penetrate the inner coal structure to extract additional soluble materials. Additional coal extracts of 3%-9% were obtained by these treatments. The yield of coal extract could also be enhanced ultrasonically because of the molecular bond rupture in coal network by high sound intensities.

The effects of demineralization and LAH reduction were studied by the FT-IR spectra of pyridine extracts and residues in different treatment stages. Elemental analyses for C, H, N, S in coal extracts and size exclusion chromatography were also used in this research.

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