Richard E. Tischer

A surface spectroscopic study of Coz.sbnd;MoAl2O3 catalysts using ESCA, ISS, XRD, and Raman spectroscopy, I

Abstract Laser Raman spectroscopy, X-ray photoelectron spectroscopy, low-energy ion-scattering spectroscopy, and X-ray diffraction have been used to characterize a series of Coz.sbnd;Mo Al 2 O 3 catalysts containing 15 wt% MoO 3 and 0 to 8 wt% CoO in their oxide, reduced, and sulfided forms. These data show that the catalyst surface contains CoMoO 4 and irreducible Co 2+ ions of tetrahedral symmetry when the CoO concentration is 0 to 6%. With 7 to 8% CoO, additional surface species includes Co 3 O 4 crystallites on the γ-Al 2 O 3 surface. Formation of Co 3 O 4 coincides with an increased Mo reducibility and a decreased BET surface area. These results are compared to previously published data on Coz.sbnd;Mo Al 2 O 3 and suggest that the state of dehydration-dehydroxylation of the Al 2 O 3 surface before impregnation of Co and Mo affects their subsequent speciation. Autoclave studies investigating the hydrodesulfurization (HDS) and hydroconversion of coal using these catalysts are also reported. Significance of the surface speciation with respect to these activity studies is discussed.

High-reflectance and single layer MoS2: two new forms

Abstract MoS 2 has been prepared in two new physical forms by treatment of sulfided Ni-Mo/Al 2 O 3 catalysts with hydrofluoric acid. The first consists of O.2 × 3 mm pellets which do not have the cleavage present in natural molybdenite but upon crushing produce irregular shiny particles. These highly reflecting particles are crystalline and contain five to ten MoS 2 layers per crystallite. In the second form essentially all the MoS 2 is present as single layers either supported on or mixed with carbon.

Preparation of Bimodal Aluminas and Molybdena/Alumina Extrudates

Abstract Methods for preparing bimodal alumina supports and molybdena/alumina catalysts by extrusion techniques were examined. The methods used to produce bimodal pore structure in the extrudates were (1) partial peptization, (2) coextrusion of salt/boehmite mixtures, and (3) incorporation of combustible fiber such as Avicel or filter pulp. The study was limited to Conocos Catapal SB alumina. The effects of solid content of the mixture, pH of the peptizing solution, and degree of mixing on the consistency of the extrusion mixture and the pore size distribution of the resulting extrudates were examined. The type of cellulose fiber and its loading was found to affect the nature of the macropores produced in the extrudates. The extrudates were thermally treated to develop mesopores in the range needed for coal liquefaction catalysts (80–180 A with an average pore diameter of 120 A).

Large-pore NiMoAl2O3 catalysts for coal-liquids upgrading☆

Abstract A novel method that can produce large-pore unimodal or bimodal alumina extradates was developed. Since the method used to produce the larger-diameter pores does not involve a steaming or sintering process, the resultant supports have high surface areas, ~350 m 2 /g. Also, the technique allows catalysts with widely varying pore structures to be prepared while holding all preparation variables constant except for the extent of mixing used during preparation of the extrusion batch. These experimental supports were used to prepare NiMo catalysts for upgrading coal liquids. The results of an initial batch-screening test suggest that the resulting bimodal catalysts are more effective for upgrading coal liquids than the corresponding unimodal catalysts.

Slurry phase Fischer-Tropsch synthesis with iron-manganese catalysts

Abstract Synthesis gas was reacted over different compositions of iron-manganese Fischer-Tropsch catalysts in a slurry reactor. The reactor operates in a back-mixed mode with a continuous flow of feed gas through the catalyst suspended in the liquid medium. Four catalysts with iron-manganese ratios of 57/43, 44/56, 22/78, and 10/90 were investigated at identical process conditions after a standard activation procedure. With time on stream for each catalyst system, hydrogenation of olefins occurred, along with olefin isomerization reactions. Activity, selectivity, and stability are discussed in general. Analyses of used catalyst samples are also reported.

Catalytic hydrotreatment of coal-derived residua

Abstract An investigation was conducted to determine the activities of various coal-liquefaction residua during catalytic hydrotreatment. Residua produced at low- and high-severity coal-liquefaction conditions were employed, as well as a nondeashed residuum produced at low-severity conditions. All experimental runs were performed in a continuous-flow hydrotreating unit using Shell 324M catalyst. Except for hydrogenation activity, catalyst activity declined with a typical S-shaped deactivation curve. The properties of the spent catalysts do not depend significantly upon prior processing of the feedstock; however, the prior processing history of the feedstocks affected their reactivity and the rate of catalyst deactivation. The results indicate beneficial effects of conducting coal liquefaction at low-severity conditions and of product deashing prior to catalytic hydrotreatment.

Hydroprocessing of nondeashed coal-derived residuum: Evaluation of catalyst performance

Abstract Four commercially available catalysts were evaluated for 100 hours in a continuous-flow unit to determine their effectiveness in the hydrotreating of nondeashed coal-derived residuum. These included Shell 324M and Shell 424 (both unimodal), and Shell 317 and Amocat 1C (both bimodal). All catalysts contained nickel and molybdenum supported on alumina; compositions were, however, different. The results showed that all catalysts performed equally well, except that the desulfurization activity of Shell 424 was substantially higher than the activities of the other catalysts. The bimodal catalysts accumulated more carbonaceous material and trace metals than the unimodal catalysts. Also, their catalytic activity was similar to the activities of the unimodal catalysts.