Thomas R. Halbert

Bio: Thomas R. Halbert is an academic researcher from ExxonMobil. The author has contributed to research in topics: Naphtha & Hydrodesulfurization. The author has an hindex of 18, co-authored 51 publications receiving 978 citations.

Multi-function additive for lubricating oils

Abstract: OF THE DISCLOSURE A lubricating oil composition is provided which comprises a major amount of an oil of lubricating viscosity and a minor amount of an additive having the formula Mo4S4L6 in which L is a ligand selected from dithiocarbamates, dithiophosphates, dithiophosphinates, thioxanthates, and mixtures thereof and in which the ligands, L, have organo groups having a sufficient number of carbon atoms to render the additive soluble in the oil. In general, the organo groups of the ligands, L, will be the same, although they may be different and they preferably are selected from alkyl, aryl, substituted aryl and ether groups. For example, when L is a dialkyldithiocarbamate or a dialkyldithio-phosphate, the alkyl groups will have from about 1 to 30 carbon atoms.

Selective hydrodesulfurization process (HEN-9601)

Abstract: A process for hydrodesulfurizing naphtha feedstream wherein the reactor inlet temperature is below the dew point of the feedstock at the reactor inlet so that the naphtha will completely vaporize within the catalyst bed. It is preferred to use a catalyst comprised of about 1 to about 10 wt. % MoO3, about 0.1 to about 5 wt. % CoO supported on a suitable support material. They are also characterized as having an average medium pore diameter from about 60 Å to 200 Å, a Co/Mo atomic ratio of about 0.1 to about 1.0, a MoO3 surface concentration of about 0.5×10-4 to about 3.0×10-4 g MoO3 /m2, and an average particle size of less than about 2.0 mm in diameter.

Induced internal electron transfer reactivity of tetrathioperrhenate(VII): synthesis of the interconvertible dimers Re2(.mu.-S)2(S2CNR2)4 and [Re2(.mu.-SS2CNR2)2(S2CNR2)3][O3SCF3] (R = Me, iso-Bu)

Abstract: Rhenium sulfides, e.g., ReS{sub 2} and Re{sub 2}S{sub 7}, have long been recognized for their hydrogenation and dehydrogenation reactivity. Periodic trends in catalytic hydrodesulfurization (HDS) reveal rhenium sulfur systems to have high activity. However, discrete, soluble rhenium sulfur species have not received as much attention as have group VI sulfide systems. The tetrathiometalate anions of V, Mo, and W (VS{sub 4}{sup 3{minus}}; MoS{sub 4}{sup 2{minus}}; WS{sub 4}{sup 2{minus}}), which possess fully oxidized (d{sup 0}) metal centers and fully reduced (S{sup 2{minus}}) sulfide ligands, undergo internal redox upon reacting with external oxidants. In these reactions bound sulfide ions (S{sup 2{minus}}) serve as the reductant forming disulfide (S{sub 2}{sup 2{minus}}) concomitant with reduction of the metal center. Conspicuously, ReS{sub 4}{sup {minus}} is the only soluble tetrathiometalate whose chemistry in this regard has not been explored. Here the authors report that tetraalkylthiuram disulfide, acting as an oxidant, induces a dramatic and unprecedented 3e{sup {minus}} reduction of the Re-(VII) center of ReS{sub 4}{sup {minus}}.

Selective catalysts having silica supports for naphtha hydrodesulfurization

Abstract: A method for hydrodesulfurizing FCC naphtha is described. More particularly, a Co/Mo metal hydrogenation component is loaded on a silica or modified silica support in the presence of organic ligand and sulfided to produce a catalyst which is then used for hydrodesulfurizing FCC naphtha. The silica support has a defined pore size distribution which minimizes olefin saturation.

Secondary building units, nets and bonding in the chemistry of metal–organic frameworks

Abstract: This critical review presents a comprehensive study of transition-metal carboxylate clusters which may serve as secondary building units (SBUs) towards construction and synthesis of metal–organic frameworks (MOFs). We describe the geometries of 131 SBUs, their connectivity and composition. This contribution presents a comprehensive list of the wide variety of transition-metal carboxylate clusters which may serve as secondary building units (SBUs) in the construction and synthesis of metal–organic frameworks. The SBUs discussed here were obtained from a search of molecules and extended structures archived in the Cambridge Structure Database (CSD, version 5.28, January 2007) which included only crystals containing metal carboxylate linkages (241 references).

Lubricating oil compositions.

Abstract: A lubricating oil composition formulated with a viscosity index (VI) improver composition including a combination of an ethylene α-olefin copolymer having no greater than 66 mass % of units derived from ethylene, and a linear diblock copolymer including at least one block derived primarily from a vinyl aromatic hydrocarbon monomer, and at least one block derived primarily from diene monomer.

Structure and Function of the Catalyst and the Promoter in Co—Mo Hydrodesulfurization Catalysts

Abstract: Etude de la structure d'un catalyseur utilise pour une hydrodesulfuration et plus particulierement etude de la localisation et de la structure des ions molybdene et cobalt a la surface de l'alumine. Discussion sur le role d'un promoteur modifiant un catalyseur, notamment determination du nombre de sites actifs

Importance of Co-Mo-S Type Structures in Hydrodesulfurization

Abstract: The great current interest in hydrodesulfurization (HDS) and other hydrotreating reactions is related to the need for efficient upgrading of crude oil fractions or coal-derived liquids. The catalysts used for such reactions generally consist of molybdenum (or tungsten) supported on high surface area aluminas with cobalt or nickel added as promoters. Great efforts have been devoted to the understanding of the structural and chemical form in which the different elements are present in the active catalyst and to the establishment of correlations between such information and the various catalytic functions. This massive research effort has given valuable information on many aspects of such catalyst systems (for recent reviews of the extensive literature, see, e.g., Refs. 1–11). However, it has not been possible to reach general agreement on the types of structures present in the active catalysts and the origin of promotion

Theory of asymmetric organocatalysis of Aldol and related reactions: rationalizations and predictions.

Abstract: Computational studies have led to models to understand some classic and contemporary asymmetric reactions involving organocatalysts. The Hajos−Parrish−Eder−Sauer−Wiechert reaction and intermolecular aldol reactions as well as Mannich reactions and oxyaminations catalyzed by proline and other amino acids, and Diels−Alder reactions catalyzed by MacMillan's chiral amine organocatalysts have been studied with density functional theory. Quantitative predictions for several new catalysts and reactions are provided.