Process development for solvent refined lignite: laboratory autoclave studies. Project Lignite: premium fuels from Northern Great Plains lignite. R and D report No. 106, interim report No. 2

Abstract

Batch autoclave tests were carried out in a continuing investigation of solution-hydrogenation of lignite to obtain information of help in the design and operation of a continuous process development unit to produce an upgraded solvent-refined lignite. Under a variety of test conditions conversion of over 90 percent of the moisture-ash-free lignite was achieved and a high heating value, low-ash, and low-sulfur product was made in addition to some light oils and gases. Lignite with its natural moisture can be solution-hydrogenated at high yields under pressure at elevated temperature in atmospheres of hydrogen, carbon monoxide, or carbon monoxide plus hydrogen (synthesis gas). Since the gas atmosphere for commercial plants to produce SRL would probably have to be produced from lignite, the process would be simpler if synthesis gas could be used directly rather than be converted to pure hydrogen or carbon monoxide. Tests indicated that the naturally occurring concentration of cations seemed to provide the necessary catalytic effect for the solution-hydrogenation reactions. Tests showed that a petroleum-derived carbon-black feedstock should be suitable as an initial solvent. Simulation of continuous operation using recovered solvent in successive tests indicated that use of lignite-derived solvent improved processing. Prior carbonization or drying of the lignite was detrimental to the liquefaction processes. A half hour at reaction temperature was sufficient for completion of the reaction. Lignite sized to /sup 1///sub 4/ inch could be as readily processed as -100 mesh particles. Pretreatment of lignite with phenol was beneficial when the treated lignite was liquefied without drying. Storage as long as 36 weeks under various conditions did not significantly effect the solution hydrogenation.