Phenol conversion

One of the problems with all the current phenol conversions is that a certain amount of other phenols, such as resorcinol and hydro-quinone, will be formed along with the catechol (don t ask). These species are very hard to separate from the catechol because they are all so similar. Aside of carefully monitored fractional distillation there are some vague strategies which can be found in the Chemical Abstract references 116-118. 

Wow How did Strike go from such detailed articles to this load of crap about phenol conversion Well, it s probably because Strike has never had to stoop so low as to need these methods nor... 

Ca.ta.lysis by Protons. The discovery of hydrogen peroxide hydroxylation of phenol in the presence of strong acids such as perchloric, trifluoromethane-sulfonic, or sulfuric acids allows suppression of all previous drawbacks of the process (18,19). This mode of hydroxylation gives high yields (85% based on H2O2 at phenol conversion of 5—6%). It can be mn without solvents and does not generate resorcinol. Its main advantage rehes on... 

Fig 1 Phenol conversion during ozonolysis with and without y-Al203. 

Fig. 6. Influence of catalyst weight and residence time on phenol conversion (CONV), and formation of catechol (CAT), hydroquinone (HQ) and para-benzoquinone (PBQ) over CuCl Pc-Na-Y (0.26) at 353 K see Table 6 for reaction conditions.

The TS-1 catalysed hydroxylation of phenol to a 1 1 mixture of catechol and hydroquinone (Fig. 2.16) was commercialized by Enichem (Romano et ai, 1990). This process offers definite advantages, such as higher selectivities at higher phenol conversions, compared to other catalytic systems. It also illustrates another interesting development the use of solid, recyclable catalysts for liquid phase (oxidation) processes to minimize waste production even further. 

Additional results of the enhancement in phenol conversion (to dihydroxy benzenes) and oxidation of allyl alcohol (to glycidol and allylic oxidation products) catalyzed by TS-1 in various solvents are illustrated in Fig. 46. In solvents with high dielectric constants, the heterolytic cleavage of the 0-0 bond... 

CH30H H20 (wt%) Dielectric constant (e) Phenol conversion (%) Hydroquinone + catechol (mmol) Hydroquinone/ catechol Selectivity (%)a... 

AA conversion (mol%) Product selectivity (mol%) Phenol conversion (mol%) Product selectivity (mol%) ... 

Figure 4. Phenol conversion, and o-cresol and 2,6-xylenol selectivity dependence on catalyst composition and reaction temperature with a feed composition of MeOH PhOH = 5 1, at time on stream = 3h. Note that 2,6-xylenol selectivity increases with phenol conversion, and at the expense of o-cresol with all catalyst compositions, indicating the first order conversion dependence and the sequential methylation, respectively.

Figure 7. Effect of synergism on phenol conversion over three selected compositions of Cul-xCoxFe204, x = 0.0, 0.50 and 1.0. Phenol methylation was carried out with phenohmethanohwater composition of 1 5 2 at 3500C and at WFISV of 0.869 h-1. 2,6-xylenol selectivity was maintamedat 75 mol% throughout the 50 h period.

The activity trend obtained with Cui xCoxFe204 catalysts is well supported by the surface metal ions composition determined from XPS analysis. Figure 8 displays the Cu/(Co+Fe) (Co/Fe for X = 1) ratio calculated from XPS results in the left panel and phenol conversion with products selectivity for all catalyst compositions in the right panel. This exercise is mainly to imderstand the distribution of metal ions and their heterogeneity on the smface, as it directly influences catalytic activity. On fresh catalysts, relative Cu-content decreases linearly with decreasing Cu-content and it is in good correlation with bulk Cu-content measmed by x-ray fluorescence. A high Cu/Fe ratio is found on spent catalysts at 0.25 < x < 0.75. It is to be... 

Phenol conversion 2.6-Xylenol selectivity I o-Cresol selectivity... 

Figure 8. Comparison of phenol conversion and ortho products selectivity performance of Cul-xCoxFe204 catalysts at 3250C, TOS = 3h (right panel) and atomic ratio of Cu/(Co+Fe) (or Co/Fe) on Cu-containing (Cu-less) catalysts (left panel). Note the large production of desired 2,6-xylenol and Cu/(Co+Fe) = 0.9 at x = 0.5 composition on spent catalyst. Reprinted from Journal of Catalysis, 210, Mathew T., et al., 2002, 405-417 with permission from Elsevier.

Figure 11, Time on stream dependence of (a) phenol conversion and 2-ethyl phenol selectivity and (b) 2-ethyl phenol yield at 3750C on Cul -xCoxFe204 (x = 0.0, 0.5 and 1.0). Reactant feed ratio of EtOFI PhOH = 5 1 was used with a WHSV = 0.869 h-1. Conversion and selectivity is denoted by open and solid symbols, respectively. Note an increase in 2-ethyl phenol selectivity with increasing TOS on all catalyst compositions.

Catalysts Composition (X) Metal content (Wt%) Relative Acid-base property Phenol conversion (Wt%) 2-lP selectivity (Wt%)... 

Figure 14. Time on stream dependence of (a) phenol conversion, and (b) orthoalkyl phenol selectivity on Cu0.5Co0.5Fe204 at optimum reaction conditions, described earlier. Different alkylation is indicated by the name of the alkylation agent in the left panel. 2,6-xylenol selectivity is given for methylation with MeOH/DMC.

A small amount of adipic acid, 2%, is made by hydrogenation of phenol with a palladium or nickel catalyst (150°C, 50 psi) to the mixed oil, then nitric acid oxidation to adipic acid. If palladium is used, more cyclohexanone is formed. Although the phenol route for making adipic acid is not economically advantageous because phenol is more expensive than benzene, the phenol conversion to greater cyclohexanone percentages can be used successfully for caprolactam manufacture (see next section), where cyclohexanone is necessary. 

Figure 1 plots the effect of the reaction time on phenol conversion, at 200°C the reaction was carried out in the absence of solvent. 

Figure 1. Phenol conversion as a function of the reaction time. Catalyst H-P 150.

A maximum phenol conversion of 65% was reached, due to the fact that the consumption of benzoic acid was higher than that of phenol. Indeed, despite the 1/1 load ratio, the selectivity to those products the formation of which required two moles of benzoic acid per mole of phenol, made the conversion of benzoic acid approach the total one more quickly than phenol. A non-negligible effect of catalyst deactivation was present in fact, when the catalyst was separated from the reaction mixture by filtration, and was then re-loaded without any regeneration treatment, together with fresh reactants, a conversion of 52% was obtained after 2.5 h reaction time, lower than that one obtained with the fresh catalyst, i.e., 59% (Figure 1). The extraction, by means of CH2CI2, of those compounds that remained trapped inside the zeolite pores, evidenced that the latter were mainly constituted of phenol, benzoic acid and of reaction products, with very low amount of heavier compounds, possible precursors of coke formation. 

Figure 2 plots the effect of phenol conversion on the distribution of products. The following compounds were obtained (i) phenylbenzoate, (ii) 0- and p-hydroxybenzophenone, and (iii) 0- and p-benzoylphenylbenzoate. The first product was obtained with 100% selectivity only at moderate conversion, for low reaction times. In fact, when the conversion of phenol increased due to longer reaction times. 

Figure 2. Selectivity to products as functions of phenol conversion. Catalyst H-p 150.T 200X.

Yu, J., K. E. Taylor, H. Zou, N. Biswas, and J. K. Bewtra, Phenol conversion and dimeric intermediates in horseradish peroxidase-catalyzed phenol removal from water , Environ. Sci. Technol., 28, 2154-2160 (1994). 

The catalytic activity of these supported BF3 samples was tested using the reaction of 1-octene with phenol (performed at 85°C using 0.05 M of each reactant, in 100 ml of 1,2 dichlorethane with lg of supported BF3 catalyst). Table 2 shows the phenol conversion and selectivities towards octyl-phenyl ether obtained after 23 hours reaction time. It is clear that the activity of the BF3(H20)2/SiC>2 catalyst prepared in ethanol is superior to the other samples. The activity can thus be correlated with the number and strength of Bronsted acid sites identified on these catalysts using TGIR. 

A Pd(OAc)2/phenanthroline catalytic system was reported to catalyze the benzene-to-phenol conversion in the presence of CO as a sacrificial reagent in an autoclave at 180 °C [149]. Similarly, phenol was produced from benzene with air (10-15 atm) in the presence of CO (10 atm) as a sacrificial reagent by using molybdovanadopho-phoric acids as catalysts in a liquid phase, involving acetic acid at 90 °C, while no reaction occurred in the absence of CO [150]. 

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