Liquid-phase Oxidation Of Cumene Research Articles

Carbon nanotubes catalysis in liquid-phase aerobic oxidation of hydrocarbons: Influence of nanotube impurities

Pure carbon nanotubes (CNTs) have a high electron affinity and as such are able to actively absorb free radicals. This functional feature of CNTs leads to a linear chain breakage with the formation of inert spin adducts and effective inhibition of the oxidation process. However, there is a clear contradiction in this issue in the literature with the analysis of research results indicating that CNTs exhibit antioxidant activity mainly in polymeric materials, under conditions of diffusional restrictions for oxygen access. While, in the liquid-phase oxidation of hydrocarbons by CNTs (CNTs synthesised by the thermal catalytic pyrolysis of carbon-containing raw materials (CVD-process)), the CNTs enhance catalytic processes. In this study the aerobic liquid phase oxidation of cumene and initiated (by azobisisobutyronitrile) at low-temperature (333 K) in the presence of multi-walled carbon nanotubes (MWCNTs) obtained by thermal catalytic pyrolysis of cyclohexane (catalyst-ferrocene) has been undertaken. Kinetic analysis establishes that the catalysis of the oxidation process is associated with the presence of metal compounds in the structure of the MWCNTs. These metals are residues of metal catalysts remaining in the synthesis and in the process of pyrolysis. The metals are converted, as a rule, into metal carbides and are not easily removable by treatment with mineral acids. Thus, in the presence of metals in the composition of MWCNTs, interfering parallel reactions are observed with two processes running in parallel — MWCNTs + R• (RO2 •) → •MWCNTs-R (RO2) and ROOH + M @ MWCNTs → RO• radicals (RO2•). The branching of the chain processes involving hydroperoxides suppresses the route of attachment of alkyl and peroxide radicals to the carbon cage structure of the nanotubes and the reaction proceeds in an autocatalytic mode. Contradictory conclusions regarding the effect of CNTs on the chain processes in the oxidation of organic substances (hydrocarbons, polymers) that exist in the literature are attributed to the lack of control over the presence and nature of the metal containing impurities in the CNTs.

Сумісна дія металевих мікрочастинок Co, Mn та N-гідроксифталіміду в рідкофазовому окисненні кумолу

Сумісна дія металевих мікрочастинок Co, Mn та <i>N</i>-гідроксифталіміду в рідкофазовому окисненні кумолу

Reactivity of fullerene C60 towards peroxy radicals generated by liquid-phase oxidation of cumene and ethylbenzene with oxygen

The inhibiting action of fullerene C60 on the liquid-phase initiated oxidation of cumene and ethylbenzene was studied. The apparent rate constants of inhibition by fullerene C60 of cumene and ethylbenzene oxidation were determined by measuring the amount of absorbed oxygen: (1.3±0.2)·103 and (2.0±0.3)·103 L mol−1 s−1, respectively.

Catalytic activity of Cu/MgO in liquid phase oxidation of cumene

Cumene was oxidized with air as the oxidant and Cu/MgO as the catalyst. Cu/MgO with different compositions was prepared by co-precipitation and then characterized by X-ray diffraction (XRD), H2-temperature programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The characterization results showed that CuO dispersed on MgO well in the cases that the Cu content in Cu/MgO was 1% by molar. In this catalytic system, MgO did not only act as the supporter, but also as the catalyst to activate the tertiary C-H of cumene. The conversion of cumene was increased by using CuO as the promoter on MgO catalyst. The cumene conversion and cumene hydroperoxide (CHP) selectivity were in a trade-off relationship because cumene oxidation was subject to the decomposition of CHP. Thus, the effects of the operating variables were investigated and the relevant mechanism was discussed.

Initiation of radical-chain processes with mixtures of benzoyl peroxide and azobis(isobutyronitrile)

The initiating power of binary mixture of initiators, benzoyl peroxide and azobis(isobutyronitrile), in polymerization of methyl methacrylate and in liquid-phase oxidation of cumene in acetonitrile at 339 K was studied.

The 18-Crown-6–Benzoyl Peroxide–KBr Supramolecular System in the Initiation of Homolytic Chain-Radical Cumene Oxidation

The ability of the benzoyl peroxide–potassium bromide–18-crown-6 system to initiate the liquid-phase oxidation of cumene at 298 K was found. Individual components of the initiating system, as well as the oxidation product (hydroperoxide), do not participate in the initiated oxidation reaction. The rate of initiation was determined using the inhibitor method and by measuring the initial rate of oxidation.

Metal Complexes of the Tetraethyl Ester of 4-(2-Hydroxyphenylamino)-1,3-butadiene-1,3-diphosphonic Acid and the Liquid Phase Oxidation of Cumene in their Presence

Metal Complexes of the Tetraethyl Ester of 4-(2-Hydroxyphenylamino)-1,3-butadiene-1,3-diphosphonic Acid and the Liquid Phase Oxidation of Cumene in their Presence

ChemInform Abstract: Metal Complexes of the Tetraethylester of 4‐(2‐Hydroxy‐phenyl‐amino)1,3‐butadiene‐1,3‐diphosphonic Acid and the Liquid Phase Oxidation of Cumene in Their Presence.

AbstractThe phosphonacetaldehyde (I) is coupled with the aminophenol (II) to yield the tetraester (III).

METAL COMPLEXES OF THE TETRAETHYLESTER OF 4-(2-HYDROXY-PHENYL-AMINO)-1,3-BUTADIENE-1,3-DIPHOSPHONIC ACID AND THE LIQUID PHASE OXIDATION OF CUMENE IN THEIR PRESENCE

Abstract The tetraethylester of 4-(2-hydroxy-phenylamino)-1,3-butadiene-1,3-diphosphonic acid 3 and its zinc and cobalt complexes (3-Zn, 3-Co) have been synthesized and their structures were determined by IR, 1H-NMR, 31P {1H}-NMR and 13C-NMR spectral investigations. The effect of these compounds on the liquid phase oxidation of cumene is studied and compared with that of 2-aminophenol 2 and its metal complexes 2-M. It is found that the ligand 3 shows the strongest inhibiting effect, while 3-Co, 3-Zn and 2-Co accelerate the oxidation process.

Structure and catalytic properties of copper vinylpyridine ion-exchange complexes in the liquid-phase oxidation of cumene

1. We have studied the catalytic activity of Cu(II) complexes with anion-exchange resin AN-251 in the liquid-phase oxidation of cumene. We have demonstrated by the spin-trap method that the process takes place by a radical-chain homogeneous-heterogeneous mechanism and simultaneously by a molecular mechanism. 2. We have examined the structure of the Cu(II) complexes with AN-251 by EPE and IR spectroscopy and shown that the catalyst undergoes deep-seated changes in the course of the catalytic oxidation of cumene; in particular, the methyl groups of the 2-methyl-5-vinylpyridine branches of the ion-exchange resin are oxidized to form fragments ofα-picolinic acid, and the coordination sphere of the copper(II) ions is changed.

Inhibiting action of transition-metal oxides in the liquid-phase oxidation of cumene and ethylbenzene

Inhibiting action of transition-metal oxides in the liquid-phase oxidation of cumene and ethylbenzene

The kinetics and mechanism of the oxidation of cumene by ozonized oxygen

1. Kinetic studies show that ozone undergoes chain decomposition in the course of the liquid-phase oxidation of cumene (10−3–10−3 mole/liter) by ozonated oxygen. 2. A mechanism proposed to cover this oxidation shows the ozone participating in both the primary reaction and stepwise chain extension: R\(\dot O\)2 + O3 → R\(\dot O\) + 2O2; CH3\(\dot O\)2 + O3 → CH3\(\dot O\) + 2O2; CH3\(\dot O\) + O3 → CH3\(\dot O\)2 + O2. 3. Absolute rate constants have been determined for reactions of ozone with the aromatic ring and side chain of the substrate and with the methyl peroxide radicals.

Mechanism of the liquid-phase oxidation of cumene, cyclohexene and tetralin catalysed by MnO2

Oxygen absorption by solutions of cumene, cyclohexene and tetralin in monochloro-benzene has been measured at 80, 60 and 65°C with MnO2 catalyst in the inhibition region, and shows second order rate dependence with respect to hydrocarbon concentration. The limiting rate of oxidation is satisfactorily described by a 3-parameter equation based on the reaction mechanism proposed by Neuburg et al. Statistical estimates of the parameters for cumene are given from this work and for cyclohexene and tetralin from work presented elsewhere.

Kinetics of oxidation of cumene over supported NiO and NiMoO 4 catalysts

Kinetics and catalytic behavior of NiO supported on alumina and on activated carbon and NiMoO 4 supported on alumina have been studied in the liquid phase oxidation of cumene. The catalysts have been characterized by means of DTA, TGA, X-ray, ir, and BET studies. Detailed studies of the concentration of main products of cumene along with the effect of catalyst weight, and hydrocarbon concentration on the rate of oxidation were conducted at 80 °C employing these supported catalysts. A reaction mechanism is proposed in which the catalyst plays an important role in the initiation and termination steps. Rate equations derived are in good agreement with the experimental data. It was observed that carbon as a support relative to alumina (NiO catalysts) induced increased activity, lower activation energies, and shifted the limiting oxidation rate to lower catalyst amounts.

Catalytic action of cation-substituted forms of oxidized charcoal in the liquid phase oxidation of cumene

The catalytic properties of cation-substituted forms of oxidized charcoal in the liquid-phase oxidation of cumene have been investigated. It has been shown that oxidized charcoal inhibits, and its salt forms catalyze the reaction. The catalytic activities of ion-substituted charcoals depend on both the nature of the metal and the amount of supported ions.

Kinetics of liquid phase oxidation of cumene with Cr 2O 3, MnO 2 and Fe 2O 3 catalysts

The liquid phase oxidation of cumene was investigated with Cr 2O 3, MnO 2 and Fe 2O 3 catalysts in the temperature range of 70–90 °C. It was observed that a critical hydroperoxide to catalyst ratio existed, below which the reaction did not proceed. Detailed studies of the concentrations of the main products of oxidation of cumene along with the effect of catalyst weight, and hydrocarbon concentration on the rate of oxidation were conducted employing these catalysts. The apparent activation energy for the overall oxidation was calculated to be 9.8 kcal/g mole. A reaction mechanism has been proposed and a rate expression derived is in good agreement with the experimental data.

Investigation of the pathways of initiation of the liquid-phase oxidation of cumene in the presence of platinum and palladium catalysts

1. The basic products of the liquid-phase oxidation of cumene in the presence of Pt- and Pd-black, as well as Pt and Pd applied on aluminum and silicon oxides, are cumene hydroperoxide, dimethylphenylcarbinol, and acetophenone. The rate of oxidation of cumene in the presence of applied metals is an order of magnitude higher than on the pure metals. 2. The initiation of the oxidation of cumene by Pt- and Pd-catalysts is associated with the interaction of oxygen and hydroperoxide with the catalyst. The formation of radicals by dehydrogenation of the hydrocarbon does not occur.

Heterogeneous catalytic oxidation of cumene (isopropyl benzene) in liquid phase

The liquid-phase oxidation of cumene (isopropyl benzene) with molecular oxygen at 80 °C was investigated. Cobalt II, III oxide, MnO 2, NiO and Cu 2O were used as heterogeneous catalysts. Detailed studies of the effect of catalyst weight, hydrocarbon concentration, and initial hydroperoxide concentration on the rate of oxidation were conducted employing cobalt II, III oxide as the catalyst. The oxygen absorption rate was found to be proportional to the 0.4 power with respect to the catalyst weight, and to the 1.5 power with respect to the cumene concentration. The concentrations of the main products of oxidation of cumene, cumene hydroperoxide, dimethyl phenyl carbinol and acetophenone were found to depend on the weight of catalyst. Reaction mechanisms and rate expressions for the oxidation of cumene were proposed.

The oxidation of cumene in the presence of heterogeneous oxide catalysts in the liquid phase

1. The catalytic action of metal oxides on the rate and composition of the products of liquid phase oxidation of cumene was investigated. 2. The initiating and inhibiting capacity of the oxides in the oxidation process can be interpreted considering the homolytic and heterolytic mechanisms of decomposition of the hydroperoxide on the given oxides. 3. Various oxides are characterized by a definite ratio among the reaction products, and most of the oxides are characterized by participation of the surface in the reaction of recombination of radicals. 4. For the oxides ZnO and Bi2O3, initiation of the oxidation process is not associated with the decomposition of the hydroperoxide at the RO-OH bond.

Study of the catalytic action of polyazopolyarenes in the liquid-phase oxidation of cumene

1. A study was made under standard conditions of the catalytic activity of 24 polyazopolyarenes in the reaction for the liquid-phase oxidation of cumene to cumene hydroperoxide. 2. The polyazopolyarenes containing dialkyl(arylalkyl)amino groups in the backbone of the polymer chain, and also the copolymers of aromatic diamines with chrysoidine, possess the highest catalytic activity.