S. Miseo

Preparation of bulk and supported heteropolyacid salts

Abstract We describe the preparation of bulk and supported cesium and ammonium heteropolyacid and acid salts of 12-tungstophosphoric acid. Novel synthetic schemes to prepare supported forms of insoluble cesium- and ammonium-acid salts are discussed, and their behavior in model compound isomerization and alkylation reactions is described. In particular, we discuss the egg-white morphology associated with Cs-acid salts supported on silica extrudates prepared by a novel in situ-reaction/precipitation route. We also describe hydrothermal techniques developed for directly preparing the ammonium-acid salts of 12-tungstophosphoric acid and the extension of that technique to other heteropolyacid salts.

Selective synthesis of α-olefins on Fe-Zn Fischer-Tropsch catalysts

Fe/Zn oxides promoted with K and Cu selectively produce α-olefins at typical Fischer-Tropsch synthesis conditions (2/1 H2/CO, 1 MPa, and 270°C). The simultaneous presence of K and Cu introduces a synergistic activity enhancement while maintaining the high olefin selectivity obtained by alkali promotion. Structural and morphological differences in Fe-Zn oxides prepared from ammonium glycolate complexes or precipitated from nitrate solutions have only a small influence on catalytic properties. Catalyst behavior is strongly influenced by synergistic promoter effects (Cu, K) and by the controlled in situ conversion of iron oxide precursors to carbides.

89 “Nebula”: A hydroprocessing catalyst with breakthrough activity

Abstract In this paper a new catalyst technology called NEBULA is presented. It has been developed by ExxonMobil, Akzo Nobel and Nippon Ketjen. NEBULA is based on a novel copound and it is several times more active than the hydroprocessing catalysts used in todays industrial units. The new catalyst has a much higher activity for desulfurization, dentrogenation and hydrogenation than the conventional CoMo and NiMo on alumina catalysts. The NEBULA catalyst currently in use in several commercial installations represents the biggest step forward in hydroprocessing over the last years. In this paper we will focus on the development of the NEBULA technology and on the applications for which it is appropriate.

Catalysts for producing methanol and isobutanol mixtures from synthesis gas

The coproduction of methanol and isobutanol from synthesis gas over new catalysts based on coprecipitated solid solutions of alkaline earth oxides and rare earth oxides promoted by copper has been investigated. It is shown that the catalysts are active and selective to isoalcohol synthesis at temperatures and pressures lower than those required by prior art catalysts.

Supported metal catalysts : Some interesting new leads in an old field

1. Abstract We report on a new approach for preparing Ru metal supported on silica. We show that partial decomposition of Ru impregnates on silica, formed using bifunctional organic additives, creates strongly interacting complexes that bond to and spread on silica. Reducing these complexes produces 12-15A Ru crystallites homogeneously distributed on the support. This homogeneous distribution leads to enhanced resistance to reductive sintering.

Ex-Situ TEM Sulfidation Study of Supported Copper Particles

However, certain processes occur in highly corrosive (sulfur-containing) environments, and it is often not desirable to flow such gas mixtures into the TEM for in-situ studies or even through an ex-situ system due to contamination issues. Consequently, a dedicated ex-situ treatment facility has been developed for these studies. This new facility was designed after our existing ex-situ treatment system but has its own separate reaction cell, welded feed line for sulfur-containing gases, and outlet discharge to an aqueous-based potassium hydroxide scrubber solution (Figure 1). The non-pristine system is, however, designed such that it shares a high temperature furnace with our pristine facility.

Preparation and catalytic properties of supported heteropolyacid salts

Abstract Heteropoly compounds are receiving increasing interest as environmentally compatible solid acid catalysts. Partial Cs + exchange into 12-tungstophosphoric acid converts the water soluble, low surface area ( 2 g −1 ) parent acid into submicron water-insoluble Bronsted acids with surface areas exceeding 100 m 2 g −1 . The insolubility of the Cs acid salt makes preparation of large particle supported catalysts by conventional impregnation procedures impractical, although applications in packed bed or slurry reactors require millimeter-sized pellets to avoid pressure drop or filtration problems. Here, we report on a new but simple technique that produces an eggwhite distribution of active Cs-acid salt of 12-tungstophosphoric acid within a large silica extrudate by carrying out a reaction deposition directly inside the extrudate. We examine these catalysts in aromatic alkylation reactions.

Isoalcohol synthesis from CO/H2 feedstocks

The synthesis of methanol and isobutanol from synthesis gas over copper-containing Mg y Ce(Y)O x catalysts was studied. The influence of the catalyst composition, temperature and contact time on isoalcohol productivity was established. The reaction pathway for isoalcohol synthesis was studied by adding methanol, ethanol or propanol to the reactant feed.

Rare earth modified silica-aluminas as supports for bifunctional catalysis

Abstract We have explored rare earth oxide-modified amorphous silica-aluminas as “permanent” intermediate strength acids used as supports for bifunctional catalysts. The addition of well dispersed weakly basic rare earth oxides “titrates” the stronger acid sites of amorphous silica-alumina and lowers the acid strength to the level shown by halided aluminas. Physical and chemical probes, as well as model olefin and paraffin isomerization reactions show that acid strength can be adjusted close to that of chlorided and fluorided aluminas. Metal activity is inhibited relative to halided alumina catalysts, which limits the direct metal-catalyzed dehydrocyclization reactions during paraffin reforming but does not interfere with hydroisomerization reactions.

Ex-situ TEM: Gaining Fundamental Insights into the Reduction-Oxidation-Reduction (ROR) Process in Small, Bimetallic Particles

Air regeneration of bimetallic catalysts remains an important but poorly understood area of science. The effects of the reduction-oxidation-reduction (ROR) steps on a multi-component materials nanostructure are often unknown. However, with ex-situ electron microscopy-based techniques, new insights into these structure/process variable relationships are possible. Earlier TEM studies conducted using ExxonMobil’s ex-situ treatment facility revealed that the air oxidation of solid Cu particles resulted in the development of Cu oxide hollow domes (torus structures). However, the effect of alloying the Cu was not examined.