ExxonMobil

About: ExxonMobil is a company organization based out in Irving, Texas, United States. It is known for research contribution in the topics: Catalysis & Polymerization. The organization has 16969 authors who have published 23758 publications receiving 535713 citations. The organization is also known as: Exxon Mobil Corporation & Exxon Mobil Corp..

Biological hydrogen production: not so elementary.

Abstract: Many organisms metabolize hydrogen gas by means of an enzyme called hydrogenase. The nature of the catalytic sites in the hydrogenases has long been a subject of conjecture and debate. In their Perspective, Adams and Stiefel discuss results reported in the same issue by Peters et al. in which x-ray crystallography was used to provide the first structural glimpse of the iron-only hydrogenase from the hydrogen-producing, anaerobic bacterium Clostridium pasteurianum. With this information, it is hoped that the properties of the hydrogenase enzyme can now be understood and possibly mimicked for chemical processing applications.

Method for preparing a supported metallocene-alumoxane catalyst for gas phase polymerization

Abstract: of EP0323716This invention relates to a process for preparing a supported metallocene alumoxane catalyst for use in the gas phase polymerization of olefins. The invention particularly relates to the use of silica gel containing from about 6 to about 10 percent by weight adsorbed water as the catalyst support material. It has been found that such silica gel may be safely added to an aluminum trialkyl solution to form by direct reaction with the adsorbed water content of the silica gel catalyst support material the alumoxane component of the catalyst system. An alumoxane coated silica gel is formed to which a metallocene may be added and the resulting material dried to free flowing powder. The dry free flowing powder may then be used as a supported metallocene alumoxane catalyst complex for gas phase polymerization of olefins.

Combustion Chemistry of Nitrogen

Abstract: The purpose of this chapter is to examine reactions of nitrogen-containing species that are important in high-temperature gas-phase systems so as to provide the best set of rate coefficients presently available for use in combustion chemistry modeling. Since the 1984 review of N/H/O rate coefficients by Hanson and Salimian 1984 there has been a major review of nitrogen chemistry under combustion conditions by Miller and Bowman (1989). Several compilations of evaluated rate coefficients have also appeared. We update these discussions where appropriate and then analyze a number of chemically activated reactions that are relevant to understanding nitrogen chemistry.

Photooxidation of crude oils

Abstract: Photooxidation is a potentially significant process in the degradation of crude oil spilled at sea. Moreover, a fundamental understanding of the effect of photochemical degradation on crude oil is a prerequisite for providing an accurate description of the recent history and potential fate of oil spilled in a marine environment. In this report we examine the effect of ultraviolet illumination on crude oil using a variety of techniques including gas chromatography/mass spectroscopy and X-ray absorption spectroscopy. The saturated compounds are resistant, but the aromatic compounds are particularly sensitive to photooxidation. Greater size and increasing alkyl substitution increase the sensitivity of aromatic compounds to photochemical oxidation. The photooxidized products appear in the resin and polar fractions as determined by thin-layer chroma tography. Thus, the effect of photooxidation is distinctly different from that of biodegradation, where larger and more substituted compounds are more resistant to...