Energy Fuels 2010, 24, 3086–3092 Published on Web 04/28/2010
: DOI:10.1021/ef100158v
Dispersion of Liquefaction Catalysts in Coal Using Ionic Liquids Paul Painter,* Ruveyda Cetiner, Nuerxida Pulati, Maria Sobkowiak, and Jonathan Mathews The Earth and Mineral Sciences (EMS) Energy Institute and the Departments of Materials Science and Engineering and Energy and Minerals Engineering, Penn State University, University Park, Pennsylvania 16802 Received February 8, 2010. Revised Manuscript Received April 13, 2010
It is well-known that dispersing catalysts to obtain good contact with coal particles enhances coal liquefaction. This is often accomplished using soluble catalyst precursors that are then converted to an active form. In this study, it is shown that certain ionic liquids can be used to fragment, disperse, and partially dissolve coal to such an extent that good contact can be made with commercially obtained, micrometer-size molybdenum disulfide particles by simply mixing these particles with the ionic liquid/coal dispersion. Good liquefaction yields under standard conditions are obtained using this approach.
material, such as low-rank coals that are most suitable for liquefaction, is limited. This, in turn, limits contact with catalysts, curtailing hydrogenation and hydrogenolysis activity until the coal particles have been fragmented and partially solubilized. As a result, many laboratory liquefaction studies have focused on highly dispersed catalysts or soluble precursors that can be used to directly impregnate coal or can be dispersed as part of a coal/solvent mixture.6-13 Upon heating, an active form of the catalyst is produced and yields of soluble material are enhanced, largely, it is thought, as a result of the intimate contact between coal and catalyst. A solvent or class of solvents that would simultaneously partially solubilize, fragment, disperse, and directly mediate good contact between catalysts and coal at relatively low temperatures without the use of precursors might prove to be a useful advance in this field. In recent work, we have shown that certain ionic liquids (ILs) fragment, swell, partially solubilize, and disperse a Powder River Basin (PRB) and Illinois No. 6 coal as extremely fine particles to a remarkable extent.14 This process also significantly enhances the solubility of these two coals. In this paper, we will show that this dispersion and solubilization effect can be used to pretreat coals in the presence of a commercially available molybdenum disulfide catalyst (99%), and 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim][BF4] (>98.5%), purchased from SigmaAldrich and used as received without purification. Molybdenum disulfide, MoS2, described to be in the form of micrometersized particles (
