PRODUCTION OF FOAMS, FIBERS AND PITCHES USING A COAL EXTRACTION PROCESS

This Department of Energy National Energy Technology Laboratory sponsored project developed processes for converting coal feedstocks to carbon products, including coal-derived pitch, coke foams and fibers based on solvent extraction processes. A key technology is the use of hydrogenation accomplished at elevated temperatures and pressures to obtain a synthetic coal pitch. Hydrogenation, or partial direct liquefaction of coal, is used to modify the properties of raw coal such that a molten synthetic pitch can be obtained. The amount of hydrogen required to produce a synthetic pitch is about an order of magnitude less than the amount required to produce synthetic crude oil. Hence the conditions for synthetic pitch production consume very little hydrogen and can be accomplished at substantially lower pressure. In the molten state, hot filtration or centrifugation can be used to separate dissolved coal chemicals from mineral matter and insolubles (inertinite), resulting in the production of a purified hydrocarbon pitch. Alternatively, if hydrogenation is not used, aromatic hydrocarbon liquids appropriate for use as precursors to carbon products can obtained by dissolving coal in a solvent. As in the case for partial direct liquefaction pitches, undissolved coal is removed via hot filtration or centrifugation. Excess solvent is boiled off and recovered. The resultant solid material, referred to as Solvent Extracted Carbon Ore or SECO, has been used successfully to produce artificial graphite and carbon foam

Development of Continuous Solvent Extraction Processes For Coal Derived Carbon Products

In this reporting period, tonnage quantities of coal extract were produced but solid separation was not accomplished in a timely manner. It became clear that the originally selected filtration process would not be effective enough for a serious commercial process. Accordingly, centrifugation was investigated as a superior means for removing solids from the extract. Results show acceptable performance. Petrographic analysis of filtered solids was carried out by R and D Carbon Petrography under the auspices of Koppers and consultant Ken Krupinski. The general conclusion is that the material appears to be amenable to centrifugation. Filtered solids shows a substantial pitch component as well as some mesophase, resulting in increased viscosity. This is likely a contributing reason for the difficulty in filtering the material. Cost estimates were made for the hydotreatment and digestion reactors that would be needed for a 20,000 ton per year demonstration plants, with the aid of ChemTech Inc. The estimates show that the costs of scaling up the existing tank reactors are acceptable. However, a strong recommendation was made to consider pipe reactors, which are thought to be more cost effective and potentially higher performance in large scale systems. The alternate feedstocks for coke and carbon products were used to fabricate carbon electrodes as described in the last quarterly report. Gregory Hackett successfully defended his MS Thesis on the use of these electrodes in Direct Carbon Fuel Cell (DCFC), which is excerpted in Section 2.4 of this quarterly report

DEVELOPMENT OF CONTINUOUS SOLVENT EXTRACTION PROCESSES FOR COAL DERIVED CARBON PRODUCTS

The purpose of this DOE-funded effort is to develop continuous processes for solvent extraction of coal for the production of carbon products. The largest applications are those which support metals smelting, such as anodes for aluminum smelting and electrodes for arc furnaces. Other carbon products include materials used in creating fuels for the Direct Carbon Fuel Cell, metals smelting, especially in the aluminum and steel industries, as well as porous carbon structural material referred to as ''carbon foam'' and carbon fibers. During this reporting period, coking and composite fabrication continued using coal-derived samples. These samples were tested in direct carbon fuel cells. Methodology was refined for determining the aromatic character of hydro treated liquid, based on Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared (FTIR). Tests at GrafTech International showed that binder pitches produced using the WVU solvent extraction protocol can result in acceptable graphite electrodes for use in arc furnaces. These tests were made at the pilot scale