Hydrotalcite-type anionic clays: Preparation, properties and applications.

A lubricating oil composition formulated with a viscosity index (VI) improver composition including a combination of an ethylene α-olefin copolymer having no greater than 66 mass % of units derived from ethylene, and a linear diblock copolymer including at least one block derived primarily from a vinyl aromatic hydrocarbon monomer, and at least one block derived primarily from diene monomer.

Lubricating oil compositions.

CO oxidation, although seemingly a simple chemical reaction, provides us with a panacea that reveals the richness and beauty of heterogeneous catalysis. The Fritz Haber Institute is a place where a multidisciplinary approach to study the course of such a heterogeneous reaction can be generated in house. Research at the institute is primarily curiosity driven, which is reflected in the five sections comprising this Review. We use an approach based on microscopic concepts to study the interaction of simple molecules with well-defined materials, such as clusters in the gas phase or solid surfaces. This approach often asks for the development of new methods, tools, and materials to prove them, and it is exactly this aspect, both, with respect to experiment and theory, that is a trade mark of our institute.

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CO oxidation as a prototypical reaction for heterogeneous processes

Organic catalysis over zeolites: A perspective on reaction paths within micropores

A Renaissance in Living Cationic Polymerization

Publisher Summary This chapter focuses on the selective oxidation and ammoxidation of propylene over heterogeneous catalysts that has made a major impact on both industrial and fundamental catalysis. In these processes, organic feeds are converted in the vapor phase to useful products containing the same number of carbon atoms using solid phase catalysts. Of the important catalytic processes by which the major organic chemicals are produced, heterogeneous oxidation accounts for 21% of the total output. The development of catalyst systems based on the concepts of active site isolation and appropriate metal-oxygen bond strength, has resulted in highly selective and active structures such as those based on U-Sb oxides and Bi-Mo oxides. The wealth of mechanistic information concerning the intermediates formed and their conversion pathways to selective products in the propylene oxidation/catalyst reconstruction sequence has greatly expanded the scope of understanding of the fundamental processes by which heterogeneous catalysis occurs. The chapter discusses the allylic oxidation, development of selective ammoxidation catalysts, Redox properties of catalysts, and selective oxidation and ammoxidation mechanism.

Selective Oxidation and Ammoxidation of Propylene by Heterogeneous Catalysis

Catalytic centers in selective (allylic) oxidation and ammoxidation catalysts are multimetallic and multifunctional. In the historically important bismuth molybdates, used for propylene (amm)oxidation, they are composed of (Bi3+)(Mo6+)2 complexes in which the Bi3+ site is associated with the α-H abstraction and the (Mo6+)2 site with the propylene chemisorption and O or NH insertion. An updated reaction mechanism is presented. In the Mo–V–Nb–Te–Ox systems, three crystalline phases (orthorhombic Mo7.5V1.5NbTeO29, pseudohexagonal Mo6Te2VO20, and monoclinic TeMo5O16) were identified, with the orthorhombic phase being the most important one for propane (amm)oxidation. Its active centers contain all necessary key catalytic elements (2V5+/Mo6+, 1V4+/Mo5+, 2Mo6+/Mo5+, 2Te4+) for this reaction wherein a V5+ surface site (V5+ = O ↔ 4+V•–O•) is associated with paraffin activation, a Te4+ site with α-H abstraction once the olefin has formed, and a (Mo6+)2 site with the NH insertion. Four Nb5+ centers, each surrounded by five molybdenum octahedra, stabilize and structurally isolate the catalytically active centers from each other (site isolation), thereby leading to high selectivity of the desired acrylonitrile product. A detailed reaction mechanism of propane ammoxidation to acrylonitrile is proposed. Combinatorial methodology identified the nominal composition Mo0.6V0.187Te0.14Nb0.085Ox for maximum acrylonitrile yield from propane, 61.8% (86% conversion, 72% selectivity at 420 °C). We propose that this system, composed of 60% Mo7.5V1.5NbTeO29, 40% Mo6Te2VO20, and trace TeMo5O16, functions with a combination of compositional pinning of the optimum orthorhombic Mo7.5V1.5±xNb1±yTe1±zO29±δ phase and symbiotic mop-up of olefin intermediates through phase cooperation. Under mild reaction conditions, a single optimum orthorhombic composition might suffice as the catalyst; under demanding conditions this symbiosis is additionally required. Improvements in catalyst performance could be attained by further optimization of the elemental distributions at the active catalytic center of Mo7.5V1.5NbTeO29, by promoter/modifier substitutions, and incorporation of compatible cocatalytic phases (preferably epitaxially matched). High-throughput methods will greatly accelerate the rational catalyst design processes.

Multifunctionality of Active Centers in (Amm)oxidation Catalysts: From Bi–Mo–Ox to Mo–V–Nb–(Te, Sb)–Ox

Methods are revealed for producing polyolefin substituted carboxylic acylating agents having less than 1000 ppm chlorine, and reaction products formed therefrom such as dispersants. The carboxylic acylating agents are formed by reacting a polyolefin having labile halogen content with an α-β unsaturated carboxylic acid. The products formed in this invention are used in lubricating compositions.

James D. Burrington

Papers

Selective Oxidation and Ammoxidation of Propylene by Heterogeneous Catalysis

Multifunctionality of Active Centers in (Amm)oxidation Catalysts: From Bi–Mo–Ox to Mo–V–Nb–(Te, Sb)–Ox

Low chlorine content compositions for use in lubricants and fuels

Active centers in Mo-V-Nb-Te-Ox (amm)oxidation catalysts

Surface intermediates in selective propylene oxidation and ammoxidation over heterogeneous molybdate and antimonate catalysts