COAL CHEMISTRY AND CONVERSION
G.E. Dolbear & Associates, Inc., has long experience in the chemistry and technology of coal. This work has been applied to solving problems in coal cleaning and utilization and in development of new processes to make high-value products from coal.
COAL-PLEX
In the period around 1980, Occidental Petroleum developed an effective process ("Flash Pyrolysis") for making coal liquids. A group at Oxy worked closely with refinery process developer UOP to evaluate the potential for making a slate of industrial chemicals from these liquids. Several potential process combinations were evaluated before choosing one with a product slate including BTX, styrene, phenol, acetone, naphtha, and fuel products.
Geoff Dolbear and his team made detailed economic analyses for this very ambitious project. They included capital and operating costs. The project could have been profitable (DCF/ROI > 20%) if the price of oil remained above about $25 per barrel. Oxy’s economists – though not its Chairman – predicted correctly that it would not, and the project was shelved. Oil was over $30 at the time but by 1985 it fell as low as $12.
TEREPHTHALIC ACID (TPA)
In an effort to develop synergy between Occidental Petroleum’s interests in both basic chemicals and coal production, a group at Occidental sought new ways make chemicals from coal. Chemicals had long been made from coal tars in Germany, England, and the US; many of these coal tars by routes were displaced by petrochemical processes by the 1950s. Much new chemistry and many new markets were available in 1975, leading to the possibility of a revival of chemicals from coal.
The Oxy group identified a potential route to TPA using a new twist on some established chemistry. TPA is an immensely important chemical intermediate because it is one of the two starting materials for virtually all polyesters. R&D led to a novel three-step process to manufacture TPA from bituminous coal:
Geoff Dolbear supervised the group of chemists, engineers, and technicians that developed the detailed chemistry and processes to carry it out. One important development in this effort was a pair of analytical procedures that allowed rapid characterization of milligram quantities of the BCA mixture. Another was identification of coals that provided high yields of the desired products.
Over thirty patent applications resulted from this work. The work did not proceed to commercialization for a combination of reasons, including shutdown of the lab by Oxy’s cash-strapped management in 1982. Few of the patents issued before being withdrawn to save money.
COAL DRYING
In the 1980s, Unocal built and operated an integrated coal mining, cleaning and drying operation west of Edmonton, Alberta. The facility had a capacity of 700 tons of dry, low-sulfur coal per hour. Unfortunately, the original design provided a product that could not be easily transported and sold because of severe dusting problems. It also had a high tendency to spontaneous combustion in storage. Unocal Canada requested help from the R&D center in California to solve these problems. Solutions included a coating method to reduce the dusting and revised treating and storage methods to reduce spontaneous combustion problems.
CHEMICAL PRODUCTS FROM MILD PYROLYSIS
SGI International, La Jolla, has developed a process for drying Sub-Bituminous coals under conditions that change the coal chemistry to prevent re-adsorption of water (http://www.sgiinternational.com). This process was successfully demonstrated in a plant in Wyoming.
A byproduct of this "mild pyrolysis" process is a small but valuable organic liquid stream. Members of the G.E. Dolbear & Associates team worked closely with SGI’s management to identify potential high-value chemical products that could be made from this stream. SGI’s technical group subsequently developed process steps to recover these products, increasing the overall profitabilty of the process.
PATENTS AND PUBLICATIONS
A sampling of publications from this work includes the following:
Properties of Coal Liquids Produced by the Occidental Flash Pyrolysis Process; G. E. Dolbear, S. C. Che, and J. R. Longanbach. SRI Int. Coal Chemistry Workshop, August, 1976.
Coal, Its Origin, Properties, and Uses; Presented by Geoff Dolbear at various colleges and universities in Southern California during 1977, 78, and 79.
Petrochemicals from Oil Shale Via One Step Pyrolysis; Z. C. Mester, G. E. Dolbear, C. C. J. Shih, and S. Sack; ACS Autumn Meeting, Kansas City, Sept 12-17, 1982.
Process of Hydrogenation of Hydrocarbon Tars; US 4,101,416; July 18, 1978; G. E. Dolbear.
Upgrading and Storage of Solid Carbonaceous Fuel; US 4,761,162; August 2, 1988; G. E. Dolbear and C. T. Ratcliffe.