ExxonMobil

About: ExxonMobil is a company organization based out in Irving, Texas, United States. It is known for research contribution in the topics: Catalysis & Polymer. 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..

How copolymers promote mixing of immiscible homopolymers

Abstract: Copolymers and stirring are commonly used to produce fine dispersions of immiscible homopolymers. Recent experiments call into question the classical view that copolymers promote the mixing by reducing the interfacial tension, suggesting rather that copolymers induce repulsive interactions between droplets and thus inhibit collision‐induced coalescence events. We present a dynamical theory of the breakup and coalescence of polymer droplets in a mixing shear flow, including hydrodynamic and repulsive interactions between droplets. We find that a low surface coverage of copolymers, of the order of one chain per square radius of gyration, is sufficient to inhibit collisions between submicron‐sized droplets, while giving a negligible reduction in interfacial tension.

Drill Pipe Buckling in Inclined Holes

Abstract: Etude theorique montrant que les tiges de forage peuvent supporter des charges de compression sans flambage dans les forages a forte inclinaison

Coordination Compounds of Polyoxovanadates with a Hexametalate Core. Chemical and Structural Characterization of [VV6O13{(OCH2)3CR}2]2−, [VV6O11(OH)2{(OCH2)3CR}2], [VIV4VV2O9(OH)4{(OCH2)3CR}2]2−, and [VIV6O7(OH)6{(OCH2)3CR}2]2−

Abstract: Reactions of the tris(hydroxymethyl)methane-derived ligands, (HOCH 2 ) 3 Cr, R=NO 2 , CH 2 OH, and CH 3 , with [(C 4 H 9 ) 4 N] 3 [H 3 V 10 O 28 ] in CH 3 CN yield the polyoxovanadate coordination complexes [(C 4 H 9 ) 4 N] 2 [V 6 O 13 {(OCH 2 ) 3 Cr} 2 ].

Continuous Partial Oxidation of Methane to Methanol Catalyzed by Diffusion-Paired Copper Dimers in Copper-Exchanged Zeolites.

Abstract: Copper-exchanged zeolites can continuously and selectively catalyze the partial oxidation of methane to methanol using only oxygen and water at low temperatures, but the genesis and nature of the active sites are currently unknown. Herein, we demonstrate that this reaction is catalyzed by a [Cu-O-Cu]2+ motif that forms via a hypothesized proton-aided diffusion of hydrated Cu ions within the cages of SSZ-13 zeolites. While various Cu configurations may be present and active for methane oxidation, a dimeric Cu motif is the primary active site for selective partial methane oxidation. Mechanistically, CH4 activation proceeds via rate-determining C-H scission to form a surface-bound C1 intermediate that can either be desorbed as methanol in the presence of H2O/H+ or completely oxidized to CO2 by gas-phase O2. High partial oxidation selectivity can be obtained with (i) high methane and water partial pressures and (ii) maximizing Cu dimer formation by using zeolites with high Al content and low Cu loadings.