The synthesis of inorganic materials by biological systems is characterized by processes that occur at close to ambient temperatures, pressures and neutral pH. This is exemplified by biosilicification in marine organisms such as diatoms while laboratory-based synthesis of silica involves extreme temperature and pH conditions. We show here that silica and titania particles may be produced by challenging the fungus Fusarium oxysporum with aqueous anionic complexes SiF62− and TiF62− respectively. Extra-cellular protein-mediated hydrolysis of the anionic complexes results in the facile room temperature synthesis of crystalline titania particles while calcination at 300 °C is required for crystallization of silica.

/pdf/fungus-mediated-biosynthesis-of-silica-and-titania-particles-2j8emztvjo.pdf

Fungus-mediated biosynthesis of silica and titania particles

The literature of olefin metathesis by heterogeneous supported catalysts, both industrial-type supported metal oxides (ReOx/Al2O3, ReOx/(SiO2–Al2O3), MoOx/SiO2, MoOx/Al2O3, MoOx/(SiO2–Al2O3), WOx/SiO2, and WOx/(SiO2–Al2O3)) and supported organometallic complexes, is comprehensively reviewed. The focus of this Review is supported metal oxide catalysts, but the well-defined supported organometallic catalyst literature is also covered because such model catalysts have the potential to bridge heterogeneous and homogeneous olefin metathesis catalysis. The recent world shortage of small olefin feedstocks has created renewed interest in olefin metathesis as a route to synthesizing small olefins and is reflected in the recent growth of the patent literature. Despite the extensive application of supported metal oxides in industry for metathesis of small and large olefins, the molecular structures and oxidation states of the catalytic active sites, surface reaction intermediates, and reaction mechanisms of this imp...

/pdf/olefin-metathesis-by-supported-metal-oxide-catalysts-57o0ix2eey.pdf

Olefin Metathesis by Supported Metal Oxide Catalysts

Hydroprocessing of Heavy Oils and Residua

A review of recent advances in catalytic hydrocracking of heavy residues

A process for converting a hydrocarbon feedstock to provide an effluent containing light olefins, the process comprising passing a hydrocarbon feedstock, the feedstock containing at least one C 1 to C 6 aliphatic hetero compound selected from alcohols, ethers, carbonyl compounds and mixtures thereof and steam in an amount whereby the feedstock contains up to 80 weight % steam, through a reactor containing a crystalline silicate catalyst to produce an effluent including propylene, the crystalline silicate having been subjected to de-alumination by a steaming step and being selected from at least one of an MFI-type crystalline silicate having a silicon/aluminium atomic ratio of from 250 to 500 and an MEL-type crystalline silicate having a silicon/aluminium atomic ratio or from 150 to 800.

Production of olefins

At least one decomposable molybdenum compound selected from the group consisting of molybdenum dithiophosphates and molybdenum dithiocarbamates is mixed with a hydrocarbon-containing feed stream. The hydrocarbon-containing feed stream containing such decomposable molybdenum compound is then contacted in a hydrovisbreaking process with hydrogen under suitable hydrovisbreaking conditions.

Hydrovisbreaking process for hydrocarbon containing feed streams

At least one decomposable compound of a metal selected from the group consisting of copper, zinc and the metals of Group III-B, Group IV-B, Group VB, Group VIB, Group VIIB and Group VIII of the Periodic Table is mixed with a hydrocarbon-containing feed stream. The hydrocarbon-containing feed stream containing such decomposable compound is then contacted with a suitable refractory inorganic material to reduce the concentration of metals, sulfur and Ramsbottom carbon residue contained in the hydrocarbon-containing feed stream. The suitable refractory inorganic material may also be slurried with the hydrocarbon-containing feed stream.

Hydrofining process for hydrocarbon-containing feed streams

Metals contained in a hydrocarbon containing feed stream are removed by contacting the hydrocarbon containing feed stream under suitable demetallization conditions with hydrogen and a catalyst composition comprising zirconium phosphate, cobalt phosphate and iron phosphate. The life and activity of the catalyst composition may be increased by introducing a decomposable metal compound selected from the group consisting of the metals of Group V-B, Group VI-B, Group VII-B and Group VIII of the Periodic Table into the hydrocarbon containing feed stream prior to contacting the hydrocarbon containing feed stream with the catalyst composition.

Demetallization of hydrocarbon containing feed streams

New developments and concepts in enhancing activities of heterogeneous metathesis catalysts

A hydrotreating process comprises contacting a substantially liquid hydrocarbon-containing feed stream, which contains compounds of sulfur and metals (preferably Ni and/or V), in the presence of a fixed catalyst bed comprising (a) at least one layer of impregnated, substantially spherical alumina-containing particles which have been prepared by a process comprising the steps of impregnating specific starting material with at least one dissolved magnesium compound and then heating the thus impregnated material at about 500°-900° C. for improved crush strength retention. In a preferred embodiment, the fixed catalyst bed further comprises at least one layer (b) of catalyst particles comprising a refractory inorganic carrier and at least one hydrogenation promoter. A composition of matter comprising the impregnated, spherical alumina-containing particles described above, and a process for preparing them are also provided.

Simon G. Kukes

Papers

Hydrovisbreaking process for hydrocarbon containing feed streams

Hydrofining process for hydrocarbon-containing feed streams

Demetallization of hydrocarbon containing feed streams

New developments and concepts in enhancing activities of heterogeneous metathesis catalysts

Treated alumina material for fixed hydrofining beds