Cobalt (silico)-aluminophosphates

Kraushaar‐Czarnetzki, Bettina; Hoogervorst, W.G.M.

doi:10.1016/0144-2449(95)96837-q

Cited by 5 publications

(6 citation statements)

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“…434 Low levels of Co(II) can be incorporated into the framework of AlPOs substituting aluminum on tetrahedral positions as shown by UV-Visible, near-IR, ESR, and 31 P NMR techniques and EXAFS. 305,[435][436][437][438][439][440][441]442 During calcination in the presence of O 2 , tetrahedral cobalt (III) and strongly distorted tetrahedral cobalt (II) species are formed in CoAPOs. The oxidized species can be reduced back to tetrahedral cobalt (II) by calcination in H 2 .…”

Section: Other Transition Metal Containing Zeolites and Other Micropomentioning

confidence: 99%

Lewis Acids as Catalysts in Oxidation Reactions: From Homogeneous to Heterogeneous Systems

2002

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I. Introduction and Scope 3837 II. Oxidation Strategies 3838 III. Lewis Acids as Oxidation Catalysts 3839 A. Oxidations by Single Electron Abstraction 3839 B. Oxidations by an Assembly of Lewis Acid, Lewis Basic and Redox Centers 3841 1. Vanadium-Based Systems 3842 2. Metal Oxides Other than Vanadium 3844 C. Oxidations via Lewis Acid−Base Adducts 3847 1. Oxidations in Homogeneous Phase 3848 2. Oxidations in Biphasic Fluorous Systems 3854 3. Heteropolyacids as Oxidation Catalysts 3855 4.

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Section: Other Transition Metal Containing Zeolites and Other Micropomentioning

confidence: 99%

Lewis Acids as Catalysts in Oxidation Reactions: From Homogeneous to Heterogeneous Systems

2002

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“…So far, only a few examples have been reported documenting a benefit of small zeolite crystals being effective even in shaped catalyst bodies [1,2]. These cases refer to the implementation of nanosized zeolite Beta into extruded hydrocracking catalysts, resulting in a higher bottoms cracking activity due to the higher share of external zeolite surface.…”

Section: Introductionmentioning

confidence: 99%

Comparing synthesis routes to nano-crystalline zeolite ZSM-5

Reding

Maurer

Kraushaar‐Czarnetzki

2003

Microporous and Mesoporous Materials

104

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Aiming at the identification of a suitable synthesis route to zeolite ZSM-5 with acidic properties and crystal diameters of about 100 nm or less, we have evaluated four different preparation methods. Three of these have been adopted from the literature, and one was developed by ourselves. The products, all of which synthesised from mixtures with a fixed Si/Al ratio of 60, were inspected by means of X-ray diffraction, scanning electron microscopy, laser-Doppler anemometry and temperature-programmed desorption of ammonia. Two methods turned out to be successful and well reproducible. The first one comprises hydrothermal crystallisation from clear solutions under autogenous pressure and has been described previously by van Grieken et al. The other approach is based on the use of colloidal silicalite-1 seed crystals in an open-vessel crystallisation at atmospheric pressure. The crystal size distribution and the Si/Al ratio of the products can be well controlled. The products from both synthesis types could be transferred into the H-form by conventional means without causing collapse of the crystal structure.

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“…83,177,280−283 In the presence of acetic acid the intermediate cyclohexanol is converted to the more stable cyclohexylacetate. 282,284 Hence, such systems suffer from the inherent disadvantages of requiring acetic acid solvent and a separate hydrolysis step. CoAlPO-5 and CoAlPO-11 molecular sieves show higher selectivity to monooxygenates and improved stability over classical homogeneous cobalt naphthenate as catalysts for low-conversion autoxidation of cyclohexane.…”

Section: Direct One-step Conversion Of Cyclohexane To Adipic Acidmentioning

confidence: 99%

Transiting from Adipic Acid to Bioadipic Acid. 1, Petroleum-Based Processes

Bart

Cavallaro

2014

Ind. Eng. Chem. Res.

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Adipic acid, which is a very important commodity chemical, is traditionally manufactured industrially by an aged and unsustainable multistep process that involves homogeneous catalysts, aggressive oxidants (concentrated nitric acid) and the production of large quantities of the greenhouse gas nitrous oxide. Much research and development into alternative and cleaner process routes to adipic acid have been carried out over the past 70 years. Improved reaction schemes have invoked variations in fossil raw materials (from benzene and phenol to cyclohexane, cyclohexanol, cyclohexanone, cyclohexene, butadiene, and adiponitrile, etc.), oxidants (O 2 , air, H 2 O 2 , t-BuOOH, ozone), catalysts (homogeneous, heterogeneous, phase transfer, biomimetic) and reaction conditions (low temperature, atmospheric pressure, and solvent-, metal-, halide-, and corrosion-free). No single proposed alternative pathwaysome of which are purely academicsimultaneously addresses the problems of petrochemical origin, toxic starting materials or reagents, generation of environmentally incompatible byproducts, use of forcing reaction conditions, and cost in an entirely satisfactory manner, despite very intense efforts. Recently, more benign bio-based reaction pathways have been proposed starting from renewables, such as glucose or vegetable oils (which will be discussed in Part 2 of this series).

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Cobalt (silico)-aluminophosphates

Cited by 5 publications

References 0 publications

Lewis Acids as Catalysts in Oxidation Reactions: From Homogeneous to Heterogeneous Systems

Lewis Acids as Catalysts in Oxidation Reactions: From Homogeneous to Heterogeneous Systems

Comparing synthesis routes to nano-crystalline zeolite ZSM-5

Transiting from Adipic Acid to Bioadipic Acid. 1, Petroleum-Based Processes

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