Liquid-phase Oxidation Of Tetralin Research Articles

Synthesis and DFT studies of robust heterogeneous Co(III) catalyst for liquid phase oxidation of tetralin

Synthesis and DFT studies of robust heterogeneous Co(III) catalyst for liquid phase oxidation of tetralin

An Extensible Framework for Capturing Solvent Effects in Computer Generated Kinetic Models

Detailed kinetic models provide useful mechanistic insight into a chemical system. Manual construction of such models is laborious and error-prone, which has led to the development of automated methods for exploring chemical pathways. These methods rely on fast, high-throughput estimation of species thermochemistry and kinetic parameters. In this paper, we present a methodology for extending automatic mechanism generation to solution phase systems which requires estimation of solvent effects on reaction rates and equilibria. The linear solvation energy relationship (LSER) method of Abraham and co-workers is combined with Mintz correlations to estimate ΔG(solv)°(T) in over 30 solvents using solute descriptors estimated from group additivity. Simple corrections are found to be adequate for the treatment of radical sites, as suggested by comparison with known experimental data. The performance of scaled particle theory expressions for enthalpic-entropic decomposition of ΔG(solv)°(T) is also presented along with the associated computational issues. Similar high-throughput methods for solvent effects on free-radical kinetics are only available for a handful of reactions due to lack of reliable experimental data, and continuum dielectric calculations offer an alternative method for their estimation. For illustration, we model liquid phase oxidation of tetralin in different solvents computing the solvent dependence for ROO• + ROO• and ROO• + solvent reactions using polarizable continuum quantum chemistry methods. The resulting kinetic models show an increase in oxidation rate with solvent polarity, consistent with experiment. Further work needed to make this approach more generally useful is outlined.

Transition metal loaded silicon carbide-derived carbons with enhanced catalytic properties

Carbide-derived carbons (CDC) with incorporated transition metal nanoparticles (∼2.5nm) were prepared using a microemulsion approach. Time-consuming post synthesis functionalization of the carbon support material can thus be avoided and nanoparticle sizes can be controlled by changing the microemulsion composition. This synthesis strategy is a technique for the preparation of highly porous carbon materials with a catalytically active component. In particular we investigated the integration of ruthenium, palladium, and platinum in a concentration ranging from 4.45 to 12wt.%. It was found that the transition metal has a considerable influence on sorption properties of resulting nanoparticle-CDC composite materials. Depending on the used metal salt additive the surface area and the pore volume ranges from 1480m2/g and 1.25cm3/g for Pt to 2480m2/g and 2.0cm3/g for Ru doped carbons. Moreover, members of this material class show impressive properties as heterogeneous catalysts. The liquid phase oxidation of tetralin and the partial oxidation of methane were studied, and electrochemical applications were also investigated. Primarily Pt doped CDCs are highly active in the oxygen reduction reaction, which is of great importance in present day fuel cell research.

CrAPO-5 catalysts having a hierarchical pore structure for the selective oxidation of tetralin to 1-tetralone

A novel CrAPO-5 material having a unique microporous–mesoporous hierarchical pore structure (CrAPO-5H) was synthesized using an organosilane surfactant to conventional CrAPO-5 reaction mixture by a one-step hydrothermal process. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), N2-adsorption isotherm and UV-visible diffuse reflectance spectroscopy, and employed as a catalyst for the liquid phase oxidation of tetralin. CrAPO-5H produced higher activity than conventional microporous CrAPO-5. Acylperoxy radicals, in situ generated from trimethylacetaldehyde and O2, were more effective as oxidant than tert-butyl hydroperoxide (t-BuOOH); 88% conversion of tetralin with 97% selectivity to 1-tetralone was obtained with the former, whereas 57% conversion with 86% selectivity was achieved using the latter at 80 °C after 8 h. The effect of reaction temperature, Cr content, solvent, and the type of aldehyde employed for the in situ generation of acylperoxy radicals on catalytic performance was investigated. Activities of CrAPO-5H remained constant after 1st catalyst recycle. A hot filtration experiment coupled with a blank test revealed that oxidation proceeded mostly on Cr sites in the CrAPO-5H, but a minor contribution from trace amount of leached Cr could not be ruled out.

Synthesis of AlPO 4-5 and CrAPO-5 using aluminum dross

AlPO 4-5 and its chromium-containing analogue, CrAPO-5, were prepared using aluminum dross in the presence of triethylamine as a structure directing agent; both Al dross powder and an extracted precipitate from Al dross in an alkali solution were used as an aluminum source. These materials were characterized by XRD, BET surface area measurement, SEM, EDX, XRF, ESR, and UV–vis spectroscopy. Their textural properties were found close to those of the corresponding reference samples prepared using pure Al(OH) 3. CrAPO-5 samples prepared from the aluminum dross were tested as a catalyst for liquid phase oxidation of tetralin using t-butyl hydroperoxide as an oxidizing agent, which showed virtually identical catalytic performances to that obtained by a reference CrAPO-5 catalyst.

Tetralin oxidation over chromium-containing molecular sieve catalysts

A series of catalysts in which a transition metal (Fe, Co, and Cr) is incorporated into MCM-41, hexagonal mesoporous aluminophosphate (HMA), and AlPO 4-5 matrix was prepared and tested for liquid phase oxidation of tetralin using tert-butyl hydroperoxide as an oxidizing agent. In general, chromium-containing catalysts showed higher catalytic activity as well as higher α-tetralone selectivity than iron or cobalt-incorporated catalysts. In addition, HMA proved more effective as a support material than MCM-41. CrHMA was the most active (64.9% conversion) and selective (80% α-tetralone selectivity) catalyst, but developed metal leaching due to its amorphous pore walls. CrAlPO 4-5, having a crystalline structure, showed higher resistance to metal leaching than CrHMA.

Activity of heterogeneous catalysts in liquid-phase oxidation of tetralin

Activity of heterogeneous catalysts in liquid-phase oxidation of tetralin

Liquid-phase oxidation of tetralin in the presence of heterogeneous catalysts

A STUDY Of heterogeneous catalysts in liquid-phase oxidation of hydrocarbons has recently at tracted increasing attention [1-3]. This interest is due to special features of the effect of the heterogeneous surface on the process as a whole and to a somewhat (in many cases) different distribution of reaction products. Typical heterogeneous catalysts of gaseous oxidation of hydrocarbons--transition metal oxides (IV and V periods) [4, 5]--were examined in most detail. Two points of view are now dealt with in the literature which are based on these investigations and concern the role of heterogeneous catalysts in liquidphase oxidation. According to the first, heterogeneous catalysts only initiate the process [2, 6]. Oi1 the other hand, it was found in many studies that in addition to the initiating effect, heterogeneous catalysts have a considerable influence on the distribution of reaction products [1, 7, 8]. This study deals with liquid-phase oxidation of tetralin in the presence of heterogeneous systems representing bivalent cobalt ions applied on zeolites, activated charcoal and silica gel. Cobalt oxide Co304 was also examined. Results obtained by oxidation of tetralin in heterogeneous catalysts were compared with results of non-catalytic oxidation and oxidation in the presence of cobalt stearate, a homogeneous catalyst.

Liquid-phase oxidation of tetralin with atmospheric oxygen at high temperatures

Liquid-phase oxidation of tetralin with atmospheric oxygen at high temperatures

Liquid-phase oxidation of tetralin by atmospheric oxygen at increased temperatures, with divalent manganese salts

Liquid-phase oxidation of tetralin by atmospheric oxygen at increased temperatures, with divalent manganese salts

The Liquid Phase Oxidation of Tetralin and p-Xylene in the Presence of Onium Salt Type Catalysts

In one of our early works, it was found that some onium salt type compounds exerted a strong catalytic effect on the oxidation of hydrocarbons. In the present work, the liquid phase oxidation of tetralin and p-xylene with oxygen was carried out in details in the presence of the onium salt type catalysts such as tetra-n-butylphosphonium, triphenylsulfonium, and tetraphenylphosphonium chlorides or bromides. By the use of these catalysts, tetralin was oxidized to tetralin hydroperoxide and p-xylene was converted to p-toluic acid and p-toluic aldehyde in mild conditions. The effect of triphenylsulfonium halides was more active than that of tetraphenyl-phosphonium halides and in particular the chlorides indicated an excellent ability in the oxidation.