STUDY OF SOLVENT AND CATALYST INTERACTIONS IN DIRECT COAL LIQUEFACTION

Major objectives of the present project are to develop a better understanding of the roles of the catalyst and the liquefaction solvent in the coal liquefaction process. An open question concerning the role of the catalyst is whether intimate contact between the catalyst and the coal particles is important or required. To answer this question, it had been planned to coat an active catalyst with a porous silica coating which was found to retain catalyst activity while preventing actual contact between catalyst and coal. Consultation with people in DuPont who coat catalysts for increasing abrasion resistance have indicated that only portions of the catalyst are coated by their process (spray drying) and that sections of uncoated catalyst remain. For that reason, it was decided to suspend the catalyst in a basket separated from the coal in the reactor. The basket walls were to be permeable to the liquefaction solvent but not to the coal particles. Several such baskets were constructed of stainless steel with holes which would not permit passage of coal particles larger than 30 mesh. Liquefactions run with the coal of greater than 30 mesh size gave normal conversion of coal to liquid in the absence of catalyst in the basket, but substantially increased conversion when Ni/Mo on alumina catalyst was in the basket. While this result is interesting and suggestive of some kind of mass transfer of soluble material occurring between the catalyst and the coal, it does not eliminate the possibility of breakdown of the coal particle into particle sizes permeable to the basket. Indeed, a small amount of fine coal has been found inside the basket. To determine whether fine coal from breakdown of the coal particles is responsible for the conversion, a new basket is being prepared with 0.5{micro}m pore size