Sidney S. Pollack

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.

Color formation in styrene-zeolite complexes

Abstract Styrene adsorbed in the channels of ZSM-5 and other zeolites and then activated by heat or irradiation produces pigmented pink to purple complexes. The complexes were prepared with zeolite containing some aluminum substituting for silicon in the structure, H + in some of the exchange sites, styrene or various substituted styrenes, and some activating agent. The colors are probably produced by cation radicals formed by the reaction of the H + of the zeolites and the site of the double bond in the vinyl group. Developing a colorimetric method for measuring the number of acid sites in zeolites may be possible.

Identification of the origin of TiO2 deposits surrounding a used hydrodesulphurization catalyst

Abstract Mineral matter from an Eastern high volatile class A bituminous coal (Homestead, Kentucky) has been examined by scanning transmission electron microscopy and energy dispersive X-ray analysis to determine the presence of titanium-containing minerals. Titanium oxide in the form of anatase (TiO 2 ) has been identified. Crystals of anatase with a similar morphology have been found deposited around particles of Co- Mo catalyst used to promote liquefaction of the coal. This deposit has a poisoning effect on the catalytic capability of the particles. It has been suggested that the origin of the anatase is either as organically bound titanium in the coal that oxidizes during the liquefaction process or as anatase crystallites within the coal that simply coalesce around the catalyst particles. The present observations indicate that most or all of the anatase deposited on and around the catalyst was present as anatase in the coal.