Oxidation n-hexane

The products of the oxidation reaction were analysed by gas chromatography (Hewlett Packard, 5880 A), employing a FID detector and equipped with a capillary column (50 m x 0.25 mm crosslinked methyl silicone gum). The reactants and products of n-hexane oxidation were analysed by gas chromatography (Hewlett Packard, 5890) equipped with a FFAP column (30 m X 0.25 mm). The identity of the products was further confined by GC-MS (Shimadzu QCMC-QP 2000A). 

In the linear versus cyclic case, n-hexane oxidizes 18.9 times as fast as cyclohexane (see Fig. 6-6) however, under slightly different conditions (same temperature and pressure, acetone solvent) and a slightly different preparation of TS-1, n-hexane oxidizes only 4.8 times as fast as cyclohexane.45 These differences in TOFs between the linear and cyclic isomers are also attributed to the size restrictions of the zeolite. When the channel diameter is increased, as in the Ti-(1 catalyst (-6.5 A), larger cycloalkanes, such as cyclododecane, can be oxidized.45... 

FIGURE 6.7 Effect of methanol on TON of n-hexane oxidation by H202 over TS-1.51... 

Szabo, V Bassir, M Gallot, JE van Neste, A Kaliaguine, S. Perovskite-type oxides synthesized by reactive grinding Part III. Kinetics of n-hexane oxidation over LaCoi. xFcxOs. Appl. catal, B Environmental, 2003, Volume 42, Issue 3, 265-277. 

Mn and Fe chemistry has shown that zeolites are excellent supports for anchoring of metallophthalocyanines. There is a report of n-hexane oxidation with O2 and zeolite-supported Cu-perchlorophthalocyanine catalyst (189) ... 

The oxyfunctionalization of linear alkanes at the terminal position is one of the major challenges of catalysis in the case of n-hexane, oxidation at the two terminal C atoms would lead to AA. However, there is a little amount of n-hexane in cracker streams, because it is easily converted to benzene. Therefore, sourcing of this hydrocarbon would be a challenge. 

Despite the relevance of these findings and the implications that they may have [43q, r] these excellent figures were not confirmed using catalysts with an identical composition and structure, namely, MnAPO-5 and MnAPO-18 [43s, t]. It was reported that n-hexane oxidation turnover rates (per redox-active Mn center) by oxygen were similar on MnAPO-5 and MnAPO-18, because the reactant may rapidly diffuse and reach the active site, regardless of the pore size in the microporous structure. No regiospedficity was detected for w-hexane oxidation to alkanols, aldehydes and ketones (7-8% terminal selectivity), and the relative reactivity of primary and secondary C—H bonds in w-hexane was identical in both catalysts and similar to that predicted from relative C—H bond energies in n-hexane. The selectivity to terminal adds was very low. 

Inverse gas chromatography parameters can also be applied in the field of cafaly-sis. In fhis way, as example, parent NaX and CaA zeolites, as well as transition metal (Co +, Mn +, Fe " )-exchanged zeolites, were evaluated for the catalytic oxidation of n-hexane. It was observed [51, 52], that although there was linear correlation between the acidity and the adsorption enthalpy of the n-hexane, there was no relationship between the acidity and the activity for n-hexane oxidation. However, if a reactivity parameter (such as Tso, temperature at which 50 % of conversion is attained) is plotted versus the adsorption heat, a so-called Volcano plot is obtained (Fig. 16.12), an optimum value of (-AH ) being observed, higher and lower values yielding to worst catalytic performance. 

Mesoporous Cu0-Fe203 composite catalysts for complete n-hexane oxidation... 

Figure 4 shows the n-hexane conversion vs. temperature on samples of various CuO content The pure Fe203 is active in the complete n-hexane oxidation. The addition of CuO up to 20 mol.% results in displacement to the lower temperature of the conversion curves, indicating an increase in the catalytic activity. Farther enhancement... 

Szabo V, Bassir M, Gallot JE, Van Neste A, Kaliaguine S. (2003). Perovskite-type oxides synthesised by reactive grinding - Part III. Kineties of n-hexane oxidation over LaCo(l-x)Fex03. CatalB-environ. 42, 265-77. 

Potassium (metal) [7440-09-7] M 39.1, m 62.3 , d 0.89. Oil was removed from the surface of the metal by immersion in n-hexane and pure Et20 for long periods. The surface oxide was next removed by scraping under ether, and the potassium was melted under vacuum. It was then allowed to flow through metal constrictions into tubes that could be sealed, followed by distillation under vacuum in the absence of mercury vapour (see Sodium). EXPLOSIVE IN WATER. 

Manganese naphthenate may he used as an oxidation catalyst. Rouchaud and Lutete have made an in-depth study of the liquid phase oxidation of n-hexane using manganese naphthenate. A yield of 83% of C1-C5 acids relative to n-hexane was reported. The highest yield of these acids was for acetic acid followed hy formic acid. The lowest yield was observed for pentanoic acid. 

On heating S9O decomposes at 32-34 °C with melting and SO2 evolution. At 20 °C the solid oxide decomposes quantitatively within 2 h to SO2 and a polymeric sulfuroxide (S 0)x with n>9. Even dissolved in carbon disulfide S9O decomposes within 20 min to a large extent with formation of SO2 as can be seen from the decrease of the infrared absorption intensity at 1134 cm (S9O) and the intensity increase at 1336 cm (SO2). The solubihty of S9O in CS2 (>21 g r at 0 °C) is much higher than in CH2CI2 (260 mg at 0 °C) while the substance is practically insoluble in n-pentane, n-hexane and tribromomethane. At -80 °C, S9O can be stored for longer periods of time without decomposition. 

Table 2 Oxidation of n-hexane with O over phthalocyanines...

Acetone, n-hexane, acetonitrile, ethyl acetate, pesticide residue analysis grade Aluminum oxide, Aluminumoxid 90, activity 11-111, 70-230 mesh MSTM (Merck) Anhydrous sodium sulfate, sodium chloride, special grade Distilled water, HPLC grade... 

In the present chapter, we report about an inveshgahon of the catalyhc performance of rahle-type V/Sb and Sn/V/Sb/Nb mixed oxides in the gas-phase ammoxidation of n-hexane. These catalysts were chosen because they exhibit intrinsic mulhfunctional properties in fact, they possess sites able to perform both the oxidahve dehydrogenahon of the alkane to yield unsaturated hydrocarbons, and the allylic ammoxidahon of the intermediate olefins to the unsaturated lutriles. These steps are those leading to the formahon of acrylonitrile in propane ammoxidahon. The SnW/Sb/(Nb)/0 system is one of those giving the best performance in propane ammoxidahon under hydrocarbon-rich condihons (8,9). 

Hydrocarbon-rich conditions imply that oxygen is the limiting reactant, due to the high oxygen-to-hydrocarbon stoichiometric ratio in n-hexane ammoxidation. Therefore, the conversion of the hydrocarbon is low this should favour, in principle, the selectivity to products of partial (amm)oxidation instead of that to combustion products. 

An interesting influence of methanol has been observed in the oxidation of n-hexane as shown in Fig. 6.7.51 To this two-phase system (10 ml n-hexane, 10... 

Water, methanol, and n-hexane do not influence the photooxidation of PVC (43), but the photodegradation is accelerated by ferric chloride (70,71) and certain other compounds containing iron (70,71,72). Purification of the polymer might be expected to enhance its photostability by removing deleterious impurities such as iron compounds that are derived from metal equipment. This type of result was obtained in one recent study (58) but not in others (30,59). In contrast, the photo-oxidative degradation of PVC should be enhanced by admixture of the polymer with materials that are unusually susceptible to photooxidation themselves. Such behavior has been observed for impact-modified PVC containing polybutadiene-based polyblends (69,73). 

V.C.8.2. Alkenes and Alkanes. When oct-l-ene was oxidized by H202/TS-1 in the presence of n-hexane, under conditions that would lead to the oxidation of each if it were used separately, epoxidation occurred preferentially (103). This result is probably an evidence of the greater nucleophilicity and, hence, coordinating ability of the alkene. 

The titanosilicate version of UTD-1 has been shown to be an effective catalyst for the oxidation of alkanes, alkenes, and alcohols (77-79) by using peroxides as the oxidant. The large pores of Ti-UTD-1 readily accommodate large molecules such as 2,6-di-ferf-butylphenol (2,6-DTBP). The bulky 2,6-DTBP substrate can be converted to the corresponding quinone with activity and selectivity comparable to the mesoporous catalysts Ti-MCM-41 and Ti-HMS (80), where HMS = hexagonal mesoporous silica. Both Ti-UTD-1 and UTD-1 have also been prepared as oriented thin films via a laser ablation technique (81-85). Continuous UTD-1 membranes with the channels oriented normal to the substrate surface have been employed in a catalytic oxidation-separation process (82). At room temperature, a cyclohexene-ferf-butylhydroperoxide was passed through the membrane and epoxidation products were trapped on the down stream side. The UTD-1 membranes supported on metal frits have also been evaluated for the separation of linear paraffins and aromatics (83). In a model separation of n-hexane and toluene, enhanced permeation of the linear alkane was observed. Oriented UTD-1 films have also been evenly coated on small 3D objects such as glass and metal beads (84, 85). 

Because many other chemicals can affect the enzymes responsible for n-hexane metabolism (see Section 2.3.3, Metabolism), the possibility of interactions is a significant concern. The initial step in n-hexane metabolism is oxidation to a hexanol by a cytochrome P-450 isozyme other chemicals can induce these enzymes, possibly increasing the rate of metabolism to the neurotoxic 2,5-hexanedione, or competing with M-hexanc and its metabolites at enzyme active sites, reducing the rate of metabolism. Interactive effects can be concentration and/or duration dependent. 

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