Cobalt catalysts containing cationic

During investigation of cobalt-zeolite catalysts the dependence of activity on the manner by which the active phase was introduced was established. Sample of 10% CoO/H-TsVN (Si02/Al203=37) (in which cobalt was introduced by soaking) had low activity in the selective catalytic reduction of NO with CH. Conversion of 25% of NO was achieved at 320 °C, which is considerably lower than for cobalt containing cation-decationated form of zeolite with the pentasil structure, obtained by ion exchange in the solid phase (e.g., on Co-H-TsVN an 80% conversion of NO was obtained at 310 °C) [8]. 

Like the carbonylation of epoxides, the carbonylation of aziridines occurs with increased rates and scope in the presence of catalysts containing a Lewis acidic cation and Co(CO) " anion. A particularly active version of fliis catalyst for the carbonylation of aziridines is the uncommon species [CpjTi(THF)2]""[Co(CO)J . As shown in Equation 17.56, this catalyst is substantially more active tiian COj(CO)g for the carbonylation of N-benzyl cyclohexene imine. The carbonylation of N-tosyl-2-methylaziridine has also been accomplished (Equation 17.57), and ttiis reaction is important because of the ability to prepare optically active N-tosyl aziridines. Although the reaction catalyzed by the titanium and cobalt system occurred to only 35% conversion, the carbonylation of the N-tosyl-2-methylaziridine catalyzed by the aluminum and cobalt system occurred to completion under the same reaction conditions. 

Brookhart et al. have described the synthesis of various tetramethyl(2-methylthioethyl)cyclopentadienyl cobalt complexes 84-86, and tested them in ethylene polymerization. The activity of the catalyst has been improved as compared to the previously described catalyst containing the [Cp CoPRs] unit (see Sections 7.01.4.4.1 and 7.01.4.4.3). In order to prepare a stable cationic precursor, the complexes 86 have been synthesized (Scheme 8). ... 

The oxidation of propene to acrolein has been one of the most studied selective oxidation reaction. The catalysts used are usually pure bismuth molybdates owing to the fact that these phases are present in industrial catalysts and that they exhibit rather good catalytic properties (1). However the industrial catalysts also contain bivalent cation molybdates like cobalt, iron and nickel molybdates, the presence of which improves both the activity and the selectivity of the catdysts (2,3). This improvement of performances for a mixture of phases with respect to each phase component, designated synergy effect, has recently been attributed to a support effect of the bivalent cation molybdate on the bismuth molybdate (4) or to a synergy effect due to remote control (5) or to more or less strong interaction between phases (6). However, this was proposed only in view of kinetic data obtained on a prepared supported catalyst. 

Very recently Geus and co-workers [44, 45] have applied another method based on chemical complexes. This is the complex cyanide method to prepare both monocomponent (Fe or Co) and multicomponent Fischer-Tropsch catalysts. A large range of insoluble complex cyanides are known in which many metals can be combined, e.g. iron(n) hexacyanide and iron(m) hexacyanide can be combined with iron ions, but also with nickel, cobalt, copper, and zinc ions. Soluble complex ions of molybdenum(iv) which can produce insoluble complexes with metal cations are also known. Deposition precipitation (Section A.2.2.1.5) can be performed by injection of a solution of a soluble cyanide complex of one of the desired metals into a suspension of a suitable support in a solution of a simple salt of the other desired metal. By adjusting the cation composition of the simple salt solution, with a same cyanide, it is possible to adjust the composition of the precursor from a monometallic oxide (the case when the metallic cation is identical to that contained in the complex) to oxides containing one or several foreign elements. 

Binding energies of the different metals contained in the catalyst after calcination at 773 or 873 K results are presented in Table 1. No fundamental differences were found at either temperature. The values of B.E. obtained for Ni and Co are those typically reported for Ni0-t-NiAl204 and well-defined C0AI2O4 structmes, respectively [7,8]. Nevertheless, the results shown in Table 2 (first and fourth rows) clearly indicate that an increase in the calcination temperature preferentially favors the incorporation of Co cations into the spinel lattice, increasing the relative amount of nickel in the catalyst surface. This can be related to the greater tendency of cobalt to form a well-defined bulk spinel phase [5]. 

The Co-exchanged zeolites were not effective catalysts for the oxidation of cyclohexane. The cobalt exchanged ions were not stabilized enough by the zeolite interactions and part of these cations were released in the oxidation medium. Thus, we decided to explore the activity of P-zeolites in which cobalt ions were incorporated into the framework. We hoped that the incorporation would increase the stability of the cation within the solid. We studied the catalytic activities of cobalt substituted P-zeolites containing aluminium (Co-Al-BEA) and boron (Co-B-BEA) towards the oxidation of cyclohexane into adipic acid. 

The applications reported for polymer-supported, soluble oxidation catalysts are the use of poly(vinylbenzyl)trimethylammonium chloride for the autooxidation of 2,6-di-tert-butylphenol [8], of copper polyaniline nanocomposites for the Wacker oxidation reaction [9], of cationic polymers containing cobalt(II) phthalocyanate for the autooxidation of 2-mercaptoethanol [10] and oxidation of olefins [11], of polymer-bound phthalocyanines for oxidative decomposition of polychlorophenols [12], and of a norbornene-based polymer with polymer-fixed manganese(IV) complexes for the catalytic oxidation of alkanes [13], Noncatalytic processes can also be found, such as the use of soluble polystyrene-based sulfoxide reagents for Swern oxidation [14], The reactions listed above will be described in more detail in the following paragraphs. 

With the same concept, but using the more reactive Ti(III) cationic radical [Cp2TiCl(THF)2] or a cationic salphen aluminum complex in combination with the cobalt anion [Co(CO)4] , Coates et al. succeeded to make the epoxide or aziridine carbonylative ring expansion reaction catalytic (Scheme 60) [149]. For both substrates, it is proposed a nucleophilic attack of the cobalt anion at the least-substituted carbon atom of the three-membered ring, the latter being activated by the Lewis acidic part of the catalyst. Of note, catalysts 106 and 107 used in this reaction are described as ion pairs rather than M-Co bond containing complexes. 

In this paper, the electrochemical reduction of cobalt and nickel complexes of the ligand N,N -l,2-phenylenebis(salicylideneiminato] (salophen = L) and its relation to the electrochemical activation of CO2 is discussed. These complexes have been investigated as potential electrocatalysts of CO2 reduction. Indeed, cobalt and nickel complexes containing tetraazamacrocycles or tetradentate Schiff base ligands have been recognized as powerful catalysts in the electrochemical reduction of CO2 [4,5]. Bifunctional fixation of CO2 by nucleophilic CofQ-Schiff base complexes assisted by alkali cations coordinated to the same ligand has oeen reported [6. ... 

Vanadium-cobalt substituted aluminophosphate molecular sieve of AEI structure (VCoAPO-18) was found to be active and selective in the ODH of ethane. Its catalytic behavior can be related to the presence of redox (probably related to and Co " ") and acid sites (related to Co + cations) in addition to its unique structural properties. The conversion and ethene selectivity decreases in the order VCoAPO-18 >VO c/CoAPO-18 > CoAPO-18 [38]. At 873 K, the VCoAPO-18 catalyst showed a 50% ethene selectivity at 60% ethane conversion for an ethane/oxygen molar ratio of 4 8. Acid SAPO-34-based microporous catalysts with chabasite structure have been tested for the ODH of ethane in the temperature range of 823 to 973 K. Pure acid and La/Na containing SAPO-34 were catalytically active and a 75 ethene selectivity for 5% ethane conversion and a 60% ethane selectivity for 30% ethane conversion was observed [39]. 

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