________________________________________________________________________________________________________ Abstract - Cyclohexane oxidation is an important chemical reaction for industrial application. Cyclohexanol and cyclohexanon, also known as K-A oil, are important intermediate products for the production of nylon 6 and nylone 6,6 using oxidation of cyclone. A current process uses various metal salt. Commercially-practiced process is operated with very low conversion level, i.e. 4-6 % conversion due to severe selectivity problems. Due to higher reactivity of intermediate desired products, e.g. cyclohexanol and cyclohexanone, compared to cyclohexane leads to many byproducts formation and reduces selectivity drastically at higher conversion level. So it is restricted to operate at lower conversion level to achieve about 70-85% selectivity for K-A oil. Various metal salts like cobalt, gold, silver etc have been used as catalysts for cyclohexane oxidation. Due to stable nature of C-H bond results in higher activation energy required to carry out this reaction at higher temperature. Due to very less solubility of oxygen higher pressure is also desired. This paper discusses about the detail literature survey for cyclohexane oxidation reaction carried out using mainly oxygen or air as an oxidizing agent. With better understanding, it is expected that catalyst with better selectivity towards intermediate products will provide commercially feasible operation.
that at 0 V. For this catalyst, the second oxidation peak current density greatly increased, as shown in Figure 3(b), accelerating the oxidation of adsorbed GOR intermediates. This, however, can lead to the formation of high-order oxidation intermediates which may have stronger poisoning effect. The identification of the interme- diates formed in GOR on the PtAg nanoparticle surface is the next step to elucidate the GOR mechanism, and is underway.
activity has been recorded in Fig. 4, indicating the presence of methanol oxidation peak in the potential range between + 1.1 to + 1.3 V. On the other hand, Fig. 5 shows the effect of the scan rate on the peak current, indicating the increase of the peak current with increasing the scan rate. Stability proof of the Prepared electrocatalayst, can be assured by repetitive cycling between + 0.5 V and + 1.5 V in 0.5 M KOH + 1 M MeOH solution at temperature of 25°C and a scan rate of 50 mV s -1 , results were depicted
Spectrophotometry is a commonly used method to experimentally determine the reaction rates [14, 15]. The UV-VIS spectroscopy can measure the change of the concentrations of reactants or products over time. In this study, the UV-VIS spectroscopy was used to monitor the concentration of NBB (chemical structure shown in Figure 1) due to the absorption of the aromatic rings and azo group. Naphthol blue black (NBB) is an important acidic diazo dye in industrial applications, which has been widely used in the textile industry for dyeing wool, nylon, silk and textile printing . On the other hand, NBB also presents a high toxicity to the environment because of the presence of phenolic, anilino, naphthalene and sulfonated groups (as shown in Figure 1). In addition, it has high photo- and thermal-stability . Therefore, removing NBB from wastewater of textile industry is of great importance.
The metal catalyst loadings needed to obtain the high- est current density at temperatures ranging from 60 to 80 °C seem to be same, approximately 20–24 wt.%. In- creasing the metal loading further only reduces the current density. The same conditions are also applied to other temperatures. Increasing the metal catalyst loading to over 24 wt.% may block the active sites for the gly- cerol oxidation reaction. The catalyst is active and allows the adsorption of glycerol onto the surface of the cata- lyst. However, the amount of catalytic metal on the sup- port must be considered. A high catalyst loading will affect the thickness of the fuel cell catalyst layer due to the large volume of the carbon support. Furthermore, increasing the metal loading can contribute to the satur- ation of the electrochemically active surface area (EASA) . This may be due to the high likelihood of Pd aggre- gation, even in the presence of the support. Therefore, a high metal loading will increase the degree of nanoparti- cle aggregation and reduce the porosity, which may re- sult in mass transport limitations and reduce the catalytic activity . If the temperature and catalyst loading are increased simultaneously, the decrease in the current density may cause the PdAu alloy particles to cluster, leading to limited mass activity because of the very rapid reaction rate of the redox trans-metalation reaction for the PdAu catalyst . Figure 9b shows the current density at the oxidation peak of the gly- cerol oxidation reaction with a metal catalyst loading of 20 wt.% as a function of electrolyte temperature and NaOH concentration. By setting the metal cata- lyst loading constant at 20 wt.%, the electrolyte temperature and NaOH concentration can be varied to obtain the optimum current density.
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interesting for the ceria-hafnia system. Among the supported ceria-hafnia catalyst systems alumina supported composite oxide showed higher activity for OSC, CO oxidation and soot oxidation reaction, respectively. All the three catalytic properties are interrelated, as observed from our experimental results and physicochemical characteristics of the composite oxide systems. The fourth reaction studied was selective dehydration of 4- methylpentan-2-ol, which is used as a test reaction to evaluate the acid-base character of oxide catalysts. Among all the catalysts silica supported ceria-hafnia system showed highest activity toward the dehydration of the 4-methylpentan-2-ol selectively.
i) A reaction system was to be designed which would be s u f f i c ie n tly general in design as to permit the study o f various reactions under high pressure. Therefore i t was desirable to have the reaction vessel constructed from a m aterial which is no n ca talytic to most reactions th a t may be studied. In p a rtic u la r, the oxidation o f pseudocumene is catalyzed by bromine, io d in e , s ilv e r , copper, th e ir compounds and perhaps other m a te ria ls. However, the reaction is not c a t a ly tic a lly influenced by s ta in le ss steel [ 5 ].
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advocated the reaction to be a direct three electron transfer route based on the increase in the rate of oxidation by several orders of magnitude compared to the rates of oxidation of the two substrates taken alone. Further their studies were supported by the presence of free radicals and stiochiometry of the reaction. In the mixture oxalic acid was oxidized by one electron transfer and iso-propanol by two electron transfer process. The end products are acetone and CO 2 . The brief mechanism where in a ter-molecular complex formed was supposed to give products in a slow step as shown in scheme 3.
under − 5 °C for 3 h. Then the intermediate tert-butyl 3-oxoazetidine-1-carboxylate (V-5, 20.0 g, 116.8 mmol), dissolved in 67 mL THF, was added and continue stirred for another 2 h under − 5 °C. The mixture solution was warmed to room temperature and continue reacted for 16 h. Upon completion of the reaction, an aqueous solu- tion of sodium chloride (12.5%, 300 mL) was added, which was extracted by ethyl acetate (100 mL × 3). And then the organic phrase was washed by saturated salt solution (200 mL), concentrated under vacuum to give the desired compounds V-6 as a white solid (20.7 g, 91% yield). 1 H NMR (400 MHz, CDCl
The catalytic oxidation of CO was carried out in a ﬁxed-bed reactor system at atmospheric pressure (with the difference being that reactor is placed out of furnace, in most of the pilots ﬁxed-bed reactor is placed in the furnace). After heating gas in the furnace, it passes from the reactor. The reactor was a 4 mm I.D. (6-mm O.D.). Prior to all catalytic tests, the samples were heated in a ﬂowing 20 vol.% O 2 /N 2 mixture at 300 ° C for 40 min as a
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Ferrocene (Figure 1) is highly stable in air, so oxidation of the central iron atom from Fe (II) to Fe (III) under ambient conditions does not occur readily, but ferrocene oxidizes in air under acidic conditions to form ferrocenium cations . Oxidation of ferrocene derivatives in air under acidic conditions has also been studied by several groups  . However, because of their paramagnetic properties, ferrocenium cations are not generally analyzed by NMR, as signals from the nuclei near the diamagnetic center of ferrocene are broadened, which worsens the spectral resolution. In the present study, salts of ferrocene oxidation products and those of several ferrocene derivatives were prepared by addition of picrate. Picrate served as a counter ion for each of the oxidized compounds dur- ing LC-MS analysis employing an ESI source.
and complexing reaction between Fe(III) with fluoride ion at certain reaction conditions. The very fast response of the fluoride ion selective electrode (FISE) and its Nernstian behavior with respect to fluoride ions in acidic solutions indicated that this electrode might be employed effectively in kinetic studies of reactions involving changes in the fluoride ion concentration [25,26]. There- fore, rate of the complexing reaction of fluoride ion with Fe(III) was monitored by a FISE.
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Thermogravimetric Analysis: When subjected to TGA in air, all deposited carbon samples exhibited weight losses and the results are presented in Figure 4a which also shows those of the KK and KLY27 chars as references. Assuming the weight loss was completely due to oxidation of materials that could undergo combustion in air, such as carbon, the average combustible material content (dry basis) was found to be over 80 wt.%. The non-combustible material content (NCC) was therefore the impurities trapped in the carbon matrix. In this study, the onset combustion (or oxidation) temperature (OCT) is defined as the temperature at which the carbon powders begin to undergo significant oxidation in air. OCT values of the deposited carbon after washing with HCl (2.3 mol L 1 ) differed in a relatively narrow range from 310 to 370 o C, whilst those of the char references were about 100 o C higher. The other noticeable difference is that the TGA plots of the deposited carbon were much steeper in the weight loss period than those of the reference char samples. These TGA features of the deposited carbon may be due to the catalytic effect of the impurities (residual salts and metal oxides) during carbon oxidation in air as these were found to be very reactive with carbon at temperatures as low as 300 o C [25,26]. It could also result from variation in carbon structure and particle size due to changes in electrolysis conditions. More TGA results and discussion on rewashing the carbon with more concentrated HCl are given later.
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The radioactive cerium exchange reaction was employed to study the electron transfer reaction in perchloric acid between ceriurm (III) and cerium (IV). In particular, the study was carried out to extend previous investigations, to elucidate further, if possible, the nature of the ionic species that exist in perchloric acid solution, and to examine the various factors determining the rate of exchange.
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The synthesis of organics with electrochemical technology is one of the simplest, cheapest and efficiency methods. It uses electrons as the oxidant or reductant instead of chemical oxidant or reductant, which is favourable to separation of the target product. Electrochemical synthesis method can normally be divided into direct electrochemical and indirect electrochemical synthesis. 2- nitro-4-methysulfonyl toluene (NMST), which is the raw material of BA used in this paper, is slightly soluble in water. Thus, it may need supporting electrolyte by using the direct electrochemical, which makes the product difficult to separate. Besides, NMST and other aromatic compounds are easy to form tar-like polymer on the electrode which led to the passivation of the electrode. This indicated that the ideal way for BA is the indirect electrochemical synthesis method. There were already lots of literatures about the use of indirect electrochemical synthesis mediated by Cr 3+ /Cr 6+ , Mn 2+ /Mn 3+ , Ce 3+ /Ce 4+ and other ions [2-9]. Based on the literatures, we knew that the indirect electrochemical oxidation by using Ce 3+ /Ce 4+ and Mn 3+ /Mn 2+ as the mediator was mainly used to synthesize quinones and aldehyde, while indirect electrochemical oxidation by using Cr 3+ /Cr 6+ as the mediator was mainly used to synthesize acid. BA is an acid which has several electron-withdrawing groups, and the oxidizablity of Mn 3+ and Ce 4+ cannot meet the demand of oxidation, while the oxidizablity of Cr 6+ may be enough. In the present work, for the electrosynthesis of BA, Cr 3+ /Cr 6+ has been used as the mediator following the ex-cell method (Figure 1). The indirect electrochemical synthesis process can be operated in a closed loop which consisted of the electrogeneration of a Cr 6+ solution and the oxidation of NMST. After work up, the BA and a Cr 3+ solution were obtained. The Cr 6+ solution can be reused for the electrogeneration of the initial Cr 3+ solution. Thus, there were no problems with effluents contaminated by chromium salts. In this paper, the influence factors related to the process of liquid oxidation of NMST and electrochemical oxidation of were investigated, and the indirect electrochemical synthesis of BA with cyclic tests was also conducted.
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The kinetics relationship of electrolysis reaction can be deduced by steady-state approach or quasi-equilibrium state approach under the stable condition. The steady-state approach is not related with the concept of rate determination step and more generally applicable in theory. But if there were only one determination step in multi-step process, the quasi-equilibrium state approach is both convenient and reasonable .
A preliminary study of recycling efficiency of Copper using various alcoholic substrates was done. The catalyst was separated from the reaction mixture after each experiment by filtration, washed with solvent and dried carefully before using it in the subsequent run. It can be inferred that the catalyst can be recycled at least about four times. However, there is a progressive loss of activity accompanied by diminished yields this may be due to the leaching of metal in the catalyst  Estimation of Cu present in the recycled catalyst after four cycles re- vealed a lowering in Cu content by about 10% - 20% than that present at the start of the first cycle This partial lowering of Cu values can be due to a minor loss of catalyst during recovery after every run. The activity profile for four successive cycles is shown in Table 9.
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maximal activity of hydrogenperoxomonosulphate in the reaction was obtained under the concentration of 2·10 -2 mol L -1 . It was determined that the optimal alkali concentration under which the greatest rate of product accumulation was observed was (5-7)·10 -3 mol L -1 . Without hydrogenperoxomonosulphate in the given conditions during the first 30 min (observation time) the product formation was not proceeding. This necessary excess of potassium hydrogenperoxomonosulphate can be explained by its participation in the process of further hydrolytic cleavage of the formed on the first reaction stage corresponding S-oxides of ampicillin and oxacillin in basic medium (nucleophilic catalysis of β-lactam and tiazolidin cycles hydrolysis). Electronic spectra of light adsorbance of the formed product under the reaction of ampicillin trihydrate sulfoxide product in time are given on Fig. 2.
As shown in Figure 4 you can see that the decarburization increases when the oxidation is present (adjust -1), because the oxidation causes a chemical reaction with the temperature of the heat treatment which takes the subtraction of the surface of carbon steel, causing the carbon depletion in the surface of the material. It is also possible to finish analyzing the Figure 5 that the decarburization increases when the Furnace pressure is -25 (adjust 1) because as the pressure is achieved by injecting nitrogen gas in the oven in order to expel the oxygen before heat treatment, this pressure adjustment indicates a lower nitrogen flow which could mean
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The catalytic oxidation of CO was carried out in a fixed-bed reactor system at atmospheric pressure (with the difference being that reactor is placed out of furnace, in most of the pilots fixed-bed reactor is placed in the furnace). All inlet gases were heated in furnace, and then passed through to reactor. The reactor was a 4 mm I.D. (6-mm O.D.). Prior to all catalytic tests, the samples were heated in a flowing 20 vol.% O 2 /N 2 mixture