Design phenol conversion

In the above equations the symbols A, B, C, D designate phenol, hydrogen, cyclohexanone and cyclohexanol. Table 5.7 presents the model parameters at 423 K and 1 atm. The model takes into account the effect of the products on the reaction rate in the region of higher conversion. This feature is particularly useful for describing the product distribution in consecutive catalytic-type reactions. Note that the adsorption coefficients are different in the two reactions. Following the authors, this assumption, physically unlikely, was considered only to increase the accuracy of modeling. 

As with resoles, the central issue in design of novolacs is molecular weight. The effects of formaldehyde-to-phenol molar ratio and formaldehyde conversion on molecular weight of novolacs has been well studied and reported [192,193]. The effects of molecular weight on most of the important properties are also available [193]. These include Tg, melt viscosity, gel time, hot-plate flow, glass-plate flow. 

The interest in catechol oxidase, as well as in other copper proteins with the type 3 active site, is to a large extent due to their ability to process dioxygen from air at ambient conditions. While hemocyanin is an oxygen carrier in the hemolymph of some arthropods and mollusks, catechol oxidase and tyrosinase utilize it to perform the selective oxidation of organic substrates, for example, phenols and catechols. Therefore, establishment of structure-activity relationships for these enzymes and a complete elucidation of the mechanisms of enzymatic conversions through the development of synthetic models are expected to contribute greatly to the design of oxidation catalysts for potential industrial applications. 

At the input/output level the key design decision regards the conversion of reactants. This should obtain the optimal selectivity in useful products, whilst minimizing the occurrence of harmful species for safety and the environment When several reactants are involved, the first heuristic recommends the complete conversion of the reactant that is the most expensive or the most difficult to recycle (see Chapter 2). Thus, the complete conversion of phenol would be desirable, but... 

Thus, as the first design decision we assume partial conversion of phenol to both cyclohexanone and cyclohexanol. As a result, the unreacted phenol must be recycled. Then cyclohexanol is converted to cyclohexanone in a separate reactor,... 

Design Alternative with Partial Conversion of Phenol In this section we demonstrate the advantage of performing reactor analysis and design in a recycle structure. As explained in Chapter 2, in contrast with a standalone viewpoint this approach allows the designer to examine systemic issues, the most important being the flexibility with respect to production rate and target selectivity, before... 

Coproduction (biorefinery) of, for example, phenolic adhesives, polymers, waxes, and other products with hydrogen production from biomass is being discussed in the context of biomass gasification plant designs to improve the overall economics of biomass-to-hydrogen conversion.11 The technical and economic viability of such coproduction plants is unproven and was not considered in this analysis. 

Several of the inhibitory compounds found in hydrolyzates can be biotransformed, or, in a few cases, even be fully metabolized by yeast Conversion occurs for several of the carboxylic acids, fiirans and phenolic compounds. This suggests that continuous in situ detoxification of the hydrolyzate during the fermentation may be possible. However, diis requires a suitable mode of operation, and the bioconversion of inhibitors must be taken into account in the design of the process. 

A special device is designed to study the effect of pressure on the kinetic behaviour of a commercial phenolic resin by IR spectroscopy (FTIR). Accurate and reproducible spectra are generated, the characteristic IR peaks assigned and the reaction kinetics evaluated by monitoring the rates of peak disappearance. The pressure has the effect to increase both reaction rate and maximum conversion value. 6 refs. 

Batch time lowered by a factor of 2 catalyst loading reduced by factor of 2 Solventless system increases productivity as compared to conventional stirred tank reactor. Reaction time reduced by 80% yield increased from 83 to 94% Appropriate design of venturi loop reactor reduces chlorination batch time by a factor of 5-7 from 20 to 40 h required in a conventional stirred tank reactor. Highly efficient heat transfer in the external loop affords nearly isothermal operation at 45-50 °C, resulting in a high yield (more than 90%) of 2,4-dichloro phenol while suppressing formation of 2,6 dichloro phenol. Efficient removal of reaction by-product (hydrogen chloride) in the external gas circuit (Fig. 8.3) improves the yield Almost complete conversion of methanol in less than 1 h... 

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