In this study, Central Appalachian coal-derived fly ashes from two power plants were beneficiated in a pilot-scale facility in order to produce a product with a relatively consistent concentration of rare earth elements (REE). The <200-mesh final fly ash product was produced by removing the carbon- and Fe-rich particles prior to screening at 200 mesh (75 µm). The Plant D fly ash had high concentrations of CaO and SO₃, which were diminished through the two months when the ash was being beneficiated, representing a consequence of the heat, humidity, and excessive rainfall in the Kentucky summer. The high CaO and SO₃ concentrations through the early runs likely contributed to the lower REE in the <200-mesh products of those runs. Of the non-REE minor elements, Ba, V, Mn, Zn, and As showed the greatest between-run variations within the runs for each plant. The overall REE concentrations proved to be similar, both on a between-run basis for the individual fly ash sources and on a between-plant basis. Variations in fly ash quality will occur in larger-scale operations, so on-going attention to the fly ash quality and the response of the fly ash to beneficiation is necessary. Changes in the Plant D fly ash with time imply that both the freshness of the original ash and the length and conditions of its storage at the site of beneficiation could be factors in the quality and consistency of the processed fly ash.

The Middle Pennsylvanian, Langsettian sub-stage Clintwood coal, along with its correlatives, was one of the more important energy resources in eastern Kentucky. The coal thickens from the NE-SW-trending Belfry anticline in central Pike County to the southeast, towards the Virginia-Kentucky border. Much of the thickness increase is in the bright lithotypes below a dull lithology. The bright lithologies transition from a bright clarain + vitrain + fusain lithology to a clarain + fusain lithology to the southeast. Half of the lithotypes in the three analyzed sections exceed 1000-µg/g Rare earth elements + Y + Sc (REYSc) (ash basis). The La_N/Sm_N vs. Gd_N/Yb_N and La_N/Sm_N vs. Ce_N/Ce_N * plots suggest that the top lithotype may have had best indication of an oxidizing environment. Positive Gd_N/Gd_N* and Eu_N/Eu_N ^* in some of the lithologies suggests that there may have been a hydrothermal influence in the sediment sources and/or in the diagenesis of the coal. Consideration of La_N/Sm_N and Zr (µg/g; ash basis), Zr vs. Sr, and V/Cr vs. inertinite/(inertinite + vitrinite) indicates that the dull lithotypes existed in a distinct geochemical environment compared to the brighter lithotypes. The isolation of the dull lithotypes from the bright lithotypes is supported by principal components analysis on inertinite/(inertinite + vitrinite), La_N/Sm_N, V/Cr, Sr, and either Zr or Ln(100(TiO₂)/Al₂O₃).

The effects of 1% of Cd, In and Sn additives on the physicochemical properties and Fischer-Tropsch synthesis (FTS) performance of a 15% Co/Al₂O₃ catalyst were investigated. The fresh and spent catalysts were characterized by BET, temperature programmed reduction (TPR), H₂-chemisorption, NH₃ temperature programmed desorption (TPD), X-ray absorption near edge spectroscopy (XANES), and X ray diffraction (XRD). The catalysts were tested in a 1 L continuously stirred tank reactor (CSTR) at 220 °C, 2.2 MPa, H₂/CO = 2.1 and 20–55% CO conversion. Addition of 1% of Cd or In enhanced the reduction degree of 15%Co/Al₂O₃ by ~20%, while addition of 1% Sn slightly hindered it. All three additives adversely impacted Co dispersion by 22–32% by increasing apparent Co cluster size based on the H₂-chemisorption measurements. However, the decreased Co active site density resulting from the additives did not result in a corresponding activity loss; instead, the additives decreased the activity of the Co catalysts to a much greater extent than expected, i.e., 82–93%. The additional detrimental effect on catalyst activity likely indicates that the Cd, In and Sn additives migrated to and covered active sites during reaction and/or provided an electronic effect. XANES results showed that oxides of the additives were present during the reaction, but that a fraction of metal was also likely present based on the TPR and reaction testing results. This is in contrast to typical promoters that become metallic at or below ~350 °C, such as noble metal promoters (e.g., Pt, Ru) and Group 11 promoters (e.g., Ag, Au) on Co catalysts in earlier studies. In the current work, all three additives remarkably increased CH₄ and CO₂ selectivities and decreased C₅₊ selectivity, with the Sn and In additives having a greater effect. Interestingly, the Cd, In, or Sn additives were found to influence hydrogenation and isomerization activities. At a similar conversion level (i.e., in the range of 40–50%), the additives significantly increased 2-C₄ olefin content from 3.8 to 10.6% and n-C₄ paraffin from 50 to 61% accompanied by decreases in 1-C₄ olefin content from 48 to 30%. The Sn contributed the greatest impact on the secondary reactions of 1-olefins, followed by the In and Cd. NH₃-TPD results suggest enhanced acid sites on cobalt catalysts resulting from the additives, which likely explains the change in selectivities for the different catalysts.

Four suites of fly ash, all generated at the same power plant, were selected for the study of the distribution of rare earth elements (REE). The fly ashes represented two runs of single-seam/single-mine coals and two runs of run-of-mine coals representing several coal seams from several mines. Plots of the upper continental crust-normalized REE, other parameters derived from the normalization, and the principal components analysis of the derived REE parameters (including the sum of the lanthanides plus yttrium and the ratio of the light to heavy REE) all demonstrated that the relatively rare earth-rich Fire Clay coal-derived fly ashes have a different REE distribution, with a greater concentration of REE with a relative dominance of the heavy REE, than the other fly ashes. Particularly with the Fire Clay coal-derived fly ashes, there is a systematic partitioning of the overall amount and distribution of the REE in the passage from the mechanical fly ash collection through to the last row of the electrostatic precipitator hoppers.

The effect of activation environment (N₂, H₂ and H₂S/H₂) on the hydrocracking performance of a NiMo/Al catalyst was studied at 380 °C and 3.5 MPa using octacosane (C₂₈). The catalyst physical structure and acidity were characterized by BET, XRD, SEM-EDX and FTIR techniques. The N₂ activation generated more active nonsulfided NiMo/Al catalyst relative to the H₂ or H₂S activation (X_C28, 70–80% versus 6–10%). For a comparison, a NiMo/Si-Al catalyst was also tested after normal H₂ activation and showed higher activity at the same process conditions (X_C28, 81–99%). The high activity of the NiMo/Al (N₂ activation) and NiMo/Si-Al catalysts was mainly ascribed to a higher number of Brønsted acid sites (BAS) on the catalysts. The hydrocracking of cobalt wax using Pt/Si-Al and Pt/Al catalysts confirmed the superior activity of the Si-Al support. A double-peak product distribution occurred at C₄–C₆ and C₁₀–C₁₆ on all catalysts, which illustrates secondary hydrocracking and faster hydrocracking at the middle of the chain. The nonsulfided NiMo/Al and Pt/Al catalysts, and NiMo/Si-Al catalyst produced predominantly diesel (sel. 50–70%) and gasoline range (sel. > 50%) hydrocarbons, respectively, accompanied by some CH₄ and light hydrocarbons C₂–C₄. On the other hand, the hydrocarbon distribution of the Pt/Si-Al varied with conditions (i.e., diesel sel. 87–90% below 290 °C or gasoline sel. 60–70% above 290 °C accompanied by little CH₄) The dependence of the isomer/paraffin ratio on chain length was studied as well. The peak iso/paraffin value was observed at C₁₀–C₁₃ for the SiAl catalyst.