Products Cyclohexanol Research Articles

A bio-inspired Fe(III) complex and its use in the cyclohexane oxidation

The use of monooxygenase biomimetic catalysts has demonstrated good efficiency in the hydrocarbon oxidation. In this work we have used the complex [Fe III(HBPClNOL)(Cl) 2]·H 2O as catalyst in the cyclohexane oxidation and the products cyclohexanol, cyclohexanone and adipic acid were obtained. Cyclohexyl hydroperoxide and the tert-butyl cyclohexyl peroxide were also obtained as byproducts. The best reaction condition was reached with the system H 2O 2–acetonitrile at 50 °C, with 26.9% of yield. The investigation of the catalysis over time showed that the yields increase until 24 h, although the reaction rate is greater in the first 6 h. The electronic spectra of the complex were measured during the cyclohexane oxidation and it was possible to verify the disappearance of the bands assigned to the charge transfer from the phenolate and the chloride ligands to the iron. This indicates that electronic and/or structural changes are happening with the iron compound, confirming the existence of interaction between the complex and the oxidant.

Temperature dependence of catalytic cyclohexane partial oxidation in a polytetrafluoroethylene reactor

Polymer-supported Co(II) catalyst was prepared and its activity and selectivity in the partial oxidation of cyclohexane was determined at several temperatures in a polytetrafluoroethylene reactor (PTFE). The catalyst was characterized by means of SEM-EDX, FTIR, diffuse reflectance UV-Vis, N2 sorption, and mecury porosimetry. Activation energies were determined under steady state conditions for the net production of cyclohexanone and cyclohexanol and for cyclohexane and oxygen net consumption. Some activation energies were lower than the ones reported for the uncatalyzed process, indicating that the catalyst played an important role in the initiation of the free-radical reaction.

Cyclohexanol Production via Esterification of Cyclohexene with Formic Acid and Subsequent Hydration of the EsterReaction Kinetics

An alternative to current production routes to cyclohexanol, the esterification of cyclohexene with formic acid and subsequent splitting of the ester can overcome many of the drawbacks associated with conventional processes. The process that is being considered could be carried out in a reactive distillation column. To develop such a process, reliable data on liquid−liquid and vapor−liquid phase-splitting behavior and on reaction kinetics is of high importance. The current publication focuses on the reaction kinetic aspects of such a process. Reaction kinetic data for the three equilibrium reactions are being presented

A Method for Modeling Two- and Three-Phase Reactive Distillation Columns

An algorithm for the steady-state simulation of two- and three-phase multistage reactive distillation processes with equilibrium chemical reactions is developed. In the developed algorithm, the phase stability, phase equilibrium, and chemical reaction equilibrium calculations are preformed simultaneously. The algorithm was used to simulate a variety of two- and three-phase reactive distillation processes. The simulation results were compared against the available experimental data in the literature. Good agreement was observed between the simulation results and experimental data. A multistage reactive distillation process for the production of cyclohexanol from the hydration of cyclohexene with two liquid phases present on multiple stages was simulated. A high-purity cyclohexanol product with a high cyclohexene conversion was obtained for this process.

Catalytic Activity of Hβ Zeolite for Cyclohexyl Hydroperoxide Decomposition

The transition metal free acidic zeolite h beta has been found to be very active for the decomposition of cyclohexyl hydroperoxide. a remarkable high tof of 181.9 h(-1) was achieved with h beta, which is almost equal to the tof over 5 % ru/al2o3. the total selectivity for the main products cyclohexanol and cyclohexanone reached 84.6 %. the reaction temperature greatly affected the decomposition rate and product selectivity.

Preparation of nitrogenous polysaccharide-supported ironporphyrins and their catalysis for the aerobic oxidation of cyclohexane

The coordinations of nitrogenous polysaccharide chitosan and chitin to chloro[tetraphenylporphinato]iron(III) have been investigated by means of the FTIR and UV-VIS analysis techniques, and the effect of their coordination on the aerobic oxidation of cyclohexane catalyzed by ironporphyrin has been studied. The new Fe-N coordination bonds between ironporphyrin and chitosan or chitin were found, and their coordination constants K, which were calculated by means of Langmuirs’s adsorption isotherm equation, were 9.68 × 10−4 and 6.80 × 10−4 L/mol, respectively, at equilibrium. It is shown that the coordination of the nitrogenous polysaccharide to ironporphyrin had an important influence on both the conversion and selectivity of the aerobic oxidation of cyclohexane catalyzed by ironporphyrin. The selectivity to the cyclohexanone and cyclohexanol production, the catalyst turnover, and the rate constants k of cyclohexane oxidation increased with increasing coordination constant K.

Oxidation of cyclohexane in supercritical carbon dioxide catalyzed by iron tetraphenylporphyrin

The catalytic activities of 5,10,15,20-meso-tetraphenylporphyrinatechloroiron(III), [Fe(TPP)Cl], and 5,10,15,20-meso-tetraphenylporphyrinatechloroiron(III) encapsulated in zeolite Y, [Fe III(TPP)Y], were investigated using cyclohexane as substrate in supercritical carbon dioxide (scCO 2), using either tert-butyl-hydroperoxide ( t-BuOOH) or hydrogen peroxide (H 2O 2) as terminal oxidants. Using [Fe(TPP)Cl], in 2 h, at 0.724 g cm −3, were obtained conversions of up to 26 turnover per hour. The selectivity with [Fe(TPP)Cl] was higher in scCO 2 than in organic solvents, of up to 15% cyclohexanol production. Lower conversions were observed with the “ship in a bottle” catalyst, [Fe(TPP)Y].

Simulation and response surface analysis for the optimization of a three-phase catalytic slurry reactor

Factorial design and response surface analysis techniques were used in combination with modeling and simulation to optimize an industrial hydrogenation process. A three-phase reactor for the production of cyclohexanol by hydrogenation of phenol in the presence of the catalyst Ni/SiO 2, with a six-stage cooling system for temperature control was considered. The model equations form a system of ordinary differential equations derived from kinetic laws and steady-state balances for mass and energy for both reactants and coolant system. Initially, screening design was used to evaluate the process variables which were relevant to the cyclohexanol yield. Two statistically significant parameters (rates of hydrogen- Q H and catalyst- Q Ni) were selected and used in response surface methodology for process optimization. An improvement of 5.5% in cyclohexanol yield was observed for the optimized variables ( Q H = 259 kg/h, Q Ni = 53 kg/h).

Optimization strategy for maximizing production of cyclohexanol

The main issue objective of this work is to implement an optimIzation strategy through a two-layer structure where the search for optimal operational variables is made through of the algorithms optimization - Successive quadratic programming - SQP. The considered process is based on the hydrogenation of phenol for production of cyclo-hexanol in the presence of a nickel catalyst. The objective function to be considered for the optimization is to maximize production of cyclo-hexanol, through a steady-state model while maintaining the conversion of phenol at the exit of the reactor under environmental constraints. Factorial design and response surface analysis in a simulation study of a three-phase catalytic slurry reactor is used to identify the impact that each variable has on the system as well as the interaction among then. An improvement of 5.5% in cyclo-hexanol conversion was observed for the optimized variables (OH = 259 kg/h, ONi = 53 kg/h).The resulted model for the response surface was used as a flrst objective function for the SQP optimization. Theoptimization results can be then used as set-point values to the advanced controller

Biotransformation of cyclohexanone using immobilized Geotrichum candidum NCYC49 : Factors affecting the selectivity of the process

A screening of 416 microorganisms belonging to different taxonomical groups (bacteria, actinomycetes, yeasts and filamentous fungi) was performed looking for strains with high ketone monooxygenase activity. After that screening, the strain Geotrichum candidum NCYC49 was selected on the basis of the production of moderate yields of caprolactone from cyclohexanone, as well as the reproducibility of its culture conditions. Several strategies were followed in order to favor the monooxygenation reaction: growing cells, resting cells, lyophilized cells, and immobilization in different matrices ( Pterocladia agar, calcium alginate, polyacrylamide). Interestingly, the results obtained by immobilization in polyacrylamide or in Pterocladia agar indicate that a complete separation of the reduction and monooxygenation activities can be achieved by controlling the oxygenation conditions. Thus, reactions carried out in high oxygenation conditions (high shaking speed or low matrix concentration) displayed a very high yield in caprolactone (90–100% conversion) without detectable production of cyclohexanol. On the contrary, reactions carried out under low oxygenation conditions clearly favored the production of cyclohexanol (reduction reaction), particularly when agar was used as a matrix.

Oxidation of cyclohexane with molecular oxygen using a Schiff base cobalt complex bonded to carbamate-modified silica gel

The Schiff base [1,2-bis(salicylidene amino)phenylene]cobalt(II) complex, chemically bonded to a carbamate-modified silica gel catalyst, has been prepared by a four step procedure. The oxidation of cyclohexane was studied in the presence of this catalyst under relatively mild conditions (150–200 °C, 15–20 atm) using molecular oxygen. The catalyst was found to be very selective for the production of cyclohexanol, with cyclohexanone formed in only a small amount (45:1). This is in contrast to the commercially available processes in which cyclohexanol and cyclohexanone are both formed in appreciable amounts. The t.g.a. analysis shows the catalyst to be stable up to 211 °C and atomic absorption spectroscopy indicated negligible metal loss during 50 h use of the catalyst up to 180 °C.

Tetralkylammonium and Sodium Decatungstate Heterogenized on Silica: Effects of the Nature of Cations on the Photocatalytic Oxidation of Organic Substrates

Tetralkylammonium and sodium decatungstates have been heterogenized on silica. The so-obtained materials have been characterized by UV−vis and Fourier transform infrared spectroscopies, N2 adsorption experiments, and measurements of surface polarity. Both the anion W10O324- and the countercations are anchored on the surface of the support without undergoing any appreciable modification. The size of the cations plays a key role in determining the degree of coverage and, consequently, the surface polarity of silica. The heterogenized systems are characterized by different and tunable photoreactivities depending on the nature of the countercation. In particular, tetralkylammonium cations enhance the efficiency of cyclohexane photooxidation both to radical species and to the stable oxygenation products cyclohexanol and cyclohexanone. The cation makes the environment where the photoactive anion is localized more or less hydrophobic; this influences the possibility of the approach of the substrate and, conseque...

Cyclohexane oxidation over Cu 2O–CuO and CuO thin films deposited by CVD process on fiberglass

Cu 2O–CuO and CuO thin films on a fiberglass substrate were prepared by chemical vapor deposition (CVD) and then catalytically evaluated by cyclohexane oxidation. The fiber with a Cu 2O–CuO film showed a high catalytic activity at low temperatures, for example 43% at 350 °C, and a good selectivity to cyclohexanol production (37% at 300 °C). The fiber with a CuO film exhibited a higher catalytic activity, for example 48% at 350 °C, with a high yield of cyclohexanone (37% at 250 °C). A CuO/SiO 2 catalyst with the same CuO content gave a result similar to the CuO/fiberglass system under the same conditions examined but, on the other hand cyclohexane was cleaved giving a higher selectivity to hexenes, 30% at 250 °C. The effect of reaction temperature on the catalytic activity and selectivity of cyclohexane oxidation were investigated. At 300 °C the steady-state catalytic performance of the CuO/fiberglass experienced a slight deactivation after 4 h time-on stream from 40% to 38% of conversion, after which, the catalyst could be reused apparently without any activity loss.

Batch and Continuous Process of Cyclohexanol Production

Batch and Continuous Process of Cyclohexanol Production

Tetrachlorocyclopentadienone O-oxide, a facile oxygen atom transfer reagent: the oxidation of cyclohexane

Previous spectroscopic studies with low temperature matrices identified the carbonyl oxide tetrachlorocyclopentadienone O-oxide ( 4) as a potentially efficient O atom donor. It has now been shown that the photolysis of tetrachlorodiazocyclopentadiene ( 2) in O 2-saturated cyclohexane gives good yields of the oxidation products cyclohexanol and cyclohexanone. The intermediacy of the carbonyl oxide 4 could not be demonstrated conclusively, but the experimental evidence makes it highly probable. Yields of the products cyclohexanol and cyclohexanone were the highest so far achieved in a photo-oxidation of this type. Photo-oxidation of cyclohexane could be efficiently achieved with the neat liquid or in CCl 4 solutions at concentrations down to about 10% of the hydrocarbon. A plausible mechanism for these photo-oxidations has been proposed.

Hydrogenation of phenol over supported platinum and palladium catalysts

The vapour-phase hydrogenation of phenol over platinum and palladium supported on alumina and zeolite LTL was studied in a vertical fixed-bed high-pressure reactor. The major products of the hydrogenation reaction were cyclohexanone and cyclohexanol with cyclohexane, cyclohexene and benzene as the minor products. The selectivity for the major products was upto 99%, the conversion being influenced by temperature, feed rate and the partial pressure of hydrogen. Platinum catalysts were found to be better for the production of cyclohexanol while palladium catalysts favoured cyclohexanone production. The platinum catalysts also showed twice as much overall conversion as the palladium catalysts.

Variable analysis and mathematical model of cyclohexane oxidation reactor system

The mathematical model of cyclohexane oxidation reaction system for the production of cyclohexanol, cyclohexanone and cyclohexyl hydroperoxide in gas-liquid loop reactor in series has benn described in this article. This model could be used in engineering practice for process development and research. Based on the correlations of the variables of the mathematical model and analysis of the interaction between these variables, eleven independent variables were found. By evolutionary operation of these variables, it is expected that the existing commercial technology can be modified and the product yield may be increased. The validity of the present method has been confirmed by the results of the program computation.

Contribution of air oxygen to photooxidation of alkanes by vanadium(V) and chromium(VI) oxocomplexes

In photochemical oxygenation of cyclohexane by KVO3−CF3COOH or K2Cr2O7−Bu4NBr−H2O−CH2Cl2 in air the source of oxygen atoms in the product cyclohexanol and cyclohexanone is air dioxygen rather than a metal oxo-complex. In the absence of dioxygen the products of alkane oxygenation are not formed in either of the above systems. At pH=3, Cr(VI) does oxidize cyclohexane to cyclohexanol even in argon atmosphere.

Metabolic conversion of cyclohexane by Pacific salmon microsomal preparations

Hydrocarbons are being introduced into the marine environment from a variety of sources including combustion processes, crude oil spills, fuel oil spills, and controlled disposal such as processed ballast water. Even in the relatively clean waters of Alaska hydrocarbons are being released at an alarming rate. The purpose of this study was to determine the optimum conditions for the metabolism of a representative hydrocarbon by Coho Salmon Oncorhynchus kisutch liver microsomes. The product of cyclohexane metabolism in the salmon microsomal system was identified by gas chromatography-mass spectrometry as cyclohexanol. Conditions of the microsome incubation were varied systematically to determine the optimum temperature, pH, and ionic strength for cyclohexanol production. Cyclohexanol was quantified by capillary column gas chromatography. Maximum cyclohexanol formation was achieved at 20°C, a pH of 8·0–8·5 and an ionic strength of 0·026. A linear rate of cyclohexanol formation is seen from 0–60 min of incubation and there is an apparent decrease in the rate from 60–90 min. Poor stability of the microsomal preparation from the species studied was also identified and several stability studies have been undertaken using cyclohexane metabolism as a monitor.