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..

Detailed Composition-Based Model for Predicting the Cetane Number of Diesel Fuels

Abstract: We have developed a simple composition-based model for predicting the cetane number of diesel fuels with general applicability to any diesel fuel regardless of the refining process it originates from. The cetane number is correlated to a total of 129 different hydrocarbon lumps determined by a combination of supercritical fluid chromatography, gas chromatography, and mass spectroscopic methods. A total of 203 diesel fuels are considered in this study derived from various diesel-range refinery process streams and their commercial blends. Across the multitude of such process streams and blends, the model predicts the cetane number with a standard error of 1.25 numbers, which is well within the experimental error of the measurement.

High temperature olefin polymerization process

Abstract: The invention is directed to olefin polymerization processes using bridged hafnocene catalyst complexes comprising highly substituted noncoordinating anions that are surprisingly stable under high temperature olefin polymerization processes such that olefin copolymers having significant amount of incorporated comonomer can be prepared with high molecular weights. More specifically, the invention is a polymerization process for ethylene copolymers having a melt index of about 0.87 to about 0.930 comprising contacting, under homogeneous polymerization conditions at a reaction temperature at or above 140° C. to 225° C., ethylene and one or more comonomers capable of insertion polymerization with a bridged hafnocene catalyst complex derived from A) a biscyclopentadienyl hafnium organometallic compound having i) at least one unsubstituted cyclopentadienyl ligand or aromatic fused-ring substituted cyclopentadienyl ligand, ii) one aromatic fused-ring substituted cyclopentadienyl ligand, iii) and a covalent bridge connecting the two cyclopentadienyl ligands, said bridge comprising a single carbon or silicon atom; and B) an activating cocatalyst, precursor ionic compound comprising a halogenated tetraaryl-substituted Group 13 anion wherein each aryl substituent contains at least two cyclic aromatic rings.

Bimolecular QRRK analysis of methyl radical reactions

Abstract: Reactions which proceed through energized adducts, including radical recombinations, insertions, and addition to unsaturates, frequently exhibit unusual kinetic behavior. The branching ratios among various product channels are often complex functions of both temperature and pressure. Four such reactions involving methyl radicals are analyzed by combining chemical activation distribution functions with QRRK methods to predict rate constants for each channel. These include three oxidation paths, CH3 + O, CH3 + O2, CH3 + OH, and the addition reaction CH3 + C2H2. These predictions are compared to experiments wherever possible; generally, the agreement is quite satisfactory. Analysis of the energetics of the various reaction channels, using parameters which are readily available, provides a convenient framework for prediction. Suggested rate constants for the various channels for the four reactions are given at three pressures, 20, 760, and 7600 Torr, for the temperature range 300–2500 K. The approach used here can easily be applied to other reactions.

Process and apparatus for measuring gaseous fixed nitrogen species

Abstract: Process and apparatus for measuring total fixed gaseous nitrogen species, including NH3, NO, NO2, HCN and organic amines in gaseous mixtures. The process involves catalytic conversion at elevated temperature of all fixed nitrogen species to nitric oxide, NO, followed by chemiluminescent measurement of the resulting NO concentration. The improvement features of the process are the use of a reduced pressure gaseous sample flow to prevent N2 poisoning of the heated platinum catalyst and a preheat step of the reduced pressure gaseous mixture in an inert, non-catalytic quartz preheater prior to catalytic conversion to prevent loss of some species, such as NH3, through premature catalyzed reaction with NO and subsequent loss from the system as N2.