Reaction with Simultaneous Product Extraction

Catalytic Reaction with Simultaneous Product Extraction 

Ballivet-Tkatchanko and coworkers compared the palladium catalyzed dimerization of methyl acrylate in ionic liquids (monophasic) and IL/SCCO2 (biphasic) [20]. They found that both reactions exhibited similar selectivities for tail-to-tail 

Catalytic Conversion ofC02 in an Ionic Liquid/scC02 Biphasic Mixture 

Continuous Reactions in an Ionic Liquid/Compressed CO2 System 

Cole-Hamilton and coworkers demonstrated for the first time a flow apparatus for a continuous catalytic reaction using the biphasic system [BMIM][PF6]/scC02 [24]. 

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Catalytic Reaction with Simultaneous Product Extraction... 

Straightforward. We have therefore employed XAD-4 to combine biocatalytic synthesis with simultaneous product extraction. The system (Figure 15.8) comprises a continuously stirred tank reactor, a starting material feed pump, a product recovery loop with a (semi-) fluidized bed of XAD-4, and a pump to circulate the entire reaction mixture through the loop." ° Preliminary studies indicated that XAD-4 had no detrimental effects on E. coli JMlOl (pHBP461), hence, separation of biomass and reaction liquid prior to catechol extraction was not required. The biocatalytic reaction was carried out at very low concentrations of the toxic substrate and product. This was achieved by feeding the substrate at a rate lower than the potential bioconversion rate in the reactor. 

Another demonstration of a continuous flow operation is the psi-shaped microreactor that was used for lipase-catalyzed synthesis of isoamyl acetate in the 1-butyl-3-methylpyridinium dicyanamide/n-heptane two-phase system [144]. The chosen solvent system with dissolved Candida antarctica lipase B, which was attached to the ionic liquid/n-heptane interfacial area because of its amphiphilic properties, was shown to be highly efficient and enabled simultaneous esterification and product removal. The system allowed for simultaneous esterification and product recovery showed a threefold reaction rate increase when compared to the conventional batch. This was mainly a consequence of efficient reaction-diffusion dynamics in the microchannel system, where the developed flow pattern comprising intense emulsification provided a large interfacial area for the reaction and simultaneous product extraction. Another lipase-catalyzed isoamyl acetate synthesis in a continuously operated pressure-driven microreactor was reported by the same authors [145]. The esterification of isoamyl alcohol and acetic acid occurred at the interface between n-hexane and an aqueous phase with dissolved lipase B from Candida antarctica. Controlling flow rates of both phases reestablished a parallel laminar flow with liquid-liquid boundary in the middle of the microchannel and a separation of phases was achieved at the y-shaped exit of the microreactor (Figure 10.25). The microreactor approach demonstrated 35% conversion at residence time 36.5 s at 45 °C and at 0.5 M acetic acid and isoamyl alcohol inlet concentrations and has proven more effective and outperformed the batch operation, which could be attributed to the favorable mass and heat transfer characteristics. 

In particular, for the synthesis of optically pure chemicals, several immobilization techniques have been shown to give stable and active chiral heterogeneous catalysts. A step further has been carried out by Choi et al. [342] who immobilized chiral Co(III) complexes on ZSM-5/Anodisc membranes for the hydrolytic kinetic resolution of terminal epoxides. The salen catalyst, loaded into the macroporous matrix of Anodise by impregnation under vacuum, must exit near the interface of ZSM-5 film to contact with both biphasic reactants such as epoxides and water. Furthermore, the loading of chiral catalyst remains constant during reaction because it cannot diffuse into the pore channel of ZSM-5 crystals and is insoluble in water. The catalytic zeolite composite membrane obtained acts as liquid-liquid contactor, which combines the chemical reaction with the continuous extraction of products simultaneously (see Figure 11.28) the... 

The superiority of extractive hydrolysis over acid hydrolysis with respect to its productivity, yield, raw materials, and waste streams, for the transformation of drug intermediates (e.g. for Primaxin) in formate ester form to the corresponding alcohol, has been effectively demonstrated by King et al. (1985). They carried out the hydrolysis of the relevant formate ester with simultaneous extraction of the desired product from the undesired impurities by two-phase reaction/extraction with a base. 

The concept of extractive reaction, which was conceived over 40 years ago, has connections with acid hydrolysis of pentosans in an aqueous medium to give furfural, which readily polymerizes in the presence of an acid. The use of a water-immiscible solvent, such as tetralin allows the labile furfural to be extracted and thus prevents polymerization, increases the yield, and improves the recovery procedures. In the recent past an interesting and useful method has been suggested by Rivalier et al. (1995) for acid-catalysed dehydration of hexoses to 5-hydroxy methyl furfural. Here, a new solid-liquid-liquid extractor reactor has been suggested with zeolites in protonic form like H-Y-faujasite, H-mordenite, H-beta, and H-ZSM-5, in suspension in the aqueous phase and with simultaneous extraction of the intermediate product with a solvent, like methyl Aobutyl ketone, circulating countercurrently. 

With reversible reactions, sufficient improvement in conversion sometimes can be realized from removing the product to warrant a recycle operation. This can be done by sending the product to a separator and returning only unconverted material. Some systems, moreover, lend themselves to continuous removal of product in equipment integrated with the reactor. Extraction is thus employed in problem P4.06.13 and azeotropic distillation in problems P4.06.14 and P4.06.15. The gasoline additive, methyl-tert-butyl ether, is made in a distillation column where reaction and simultaneous separation take place. 

The most important examples of reactive separation processes (RSPs) are reactive distillation (RD), reactive absorption (RA), and reactive extraction (RE). In RD, reaction and distillation take place within the same zone of a distillation column. Reactants are converted to products, with simultaneous separation of the products and recycling of unused reactants. The RD process can be efficient in both size and cost of capital equipment and in energy used to achieve a complete conversion of reactants. Since reactor costs are often less than 10% of the capital investment, the combination of a relatively cheap reactor with a distillation column offers great potential for overall savings. Among suitable RD processes are etherifications, nitrations, esterifications, transesterifications, condensations, and alcylations (2). 

A simultaneous countercurrent movement of solid and gaseous phases makes it possible to enhance the efficiency of an equilibrium limited reaction with only one product (Fig. 4(a)) [34]. A positive effect can be obtained for the reaction A B if the catalyst has a higher adsorption capacity for B than for A. In this case, the product B will be collected mainly in the upper part of the reactor, while some fraction of the reactant A will move down with the catalyst. Better performance is achieved when the reactants are fed at some side port of the column inert carrier gas comes to the bottom and the component B is stripped off the catalyst leaving the column (Fig 4(a)). The technique was verified experimentally for the hydrogenation of 1,3,5-trimethylbenzene to 1,3,5-trimethylcyclohexane over a supported platinum catalyst [34]. High purity product can be extracted after the catalytic reactor, and overequilibrium conversion can be obtained at certain operating conditions. 

CDTech uses catalytic distillation to convert isobutene and methanol to MTBE, where the simultaneous reaction and fractionation of MTBE reactants and products takes place [51], A block diagram of this process is shown in Figure 3.31. The C4 feed from catalytic crackers undergoes fractionation to extract deleterious nitrogen compounds. It is then mixed with methanol in a BP reactor where 90% of the equilibrium reaction takes place. The reactor effluent is fed to the catalytic distillation (CD) tower where an overall isobutene conversion of 97% is achieved. The catalyst used is a conventional ion-exchange resin. This process selectively removes MTBE from the product to overcome the chemical equilibrium limitation of the reversible reaction. The MTBE product stream is further fiactionated to remove pentanes, which are sent to gasoline blending, whereas the raffinate from the catalytic distillation tower is washed with water and then fractionated to recover the methanol. 

In Section 4.2.2.2 some processes are described in which the organic products are separated - simultaneously or successively - by extraction with a nonpolar extractant. In the cases presented in this section, not the product but the catalyst will be extracted and recycled to the reactor. Theoretically, this can be done simultaneously in the reactor, as shown in Figure 12. However, this arrangement is highly unfavorable, because it means that the catalyst is taken away from the reaction medium during the catalytic conversion. The successive variant, shown in Figure 13, makes much more sense the reaction is first carried out in the reaction unit, then the catalyst is extracted by an extractant which does not dissolve the products C... 

Very recently, possibility for using simultaneous hydrolysis and glycolysis products of waste PET in alkyd resins manufacturing was reported. In this study, waste PET flakes obtained from grinding postconsummer bottles were treated with ethylene glycol and water in the presence of xylene, an emulsifier at 180°C and zinc acetate as catalyst. The reaction products were purified by filtration, extraction, crystallization and resins were prepared by reaction with phthalic acid, glycerine or oil fatty acid (31). 

The other is the removal of cobalt from the crude oxo product by treatment with chemicals. This may be achieved by reaction with aqueous acids or salts with or without simultaneous application of an oxidizing agent such as air. The resulting cobalt-containing acid solution is worked up and recycled to the reactor [840, 841]. Thus, Union Carbide removes cobalt at elevated temperatures with sulfuric or acetic acid [842]. A variation of this method was developed by Kuhlmann who extracts cobalt hydrocarbonyl from the crude oxo product by a dilute sodium bicarbonate solution. Subsequent acidification of the water layer reforms the hydrocarbonyl which is recycled to the oxo reactor as such [843]. 

Isolation of (I-l) and (I-m). a) 3,6,17-Triacetylnormorphine (I-l). Morphine N-oxide (10 mg) was heated at reflux temperature in 5 ml acetic anhydride- e for one hour. In the first several minutes of the reaction, the solution appeared exothermic with simultaneous color changes (yellow to red to light brown). The solution was then cooled to room temperature, and water (10 ml) was added. When the mixture became homogeneous, solid sodium carbonate was added to pH 9.0. The mixture was extracted with 3x125 ml portions of ether.The extracts were combined and evaporated to dryness. The ether extract was mixed till homogeneous with 8g celite, 10 ml 1% perchloric acid and 10 ml ether to comprise the top layer of a partition column (2.5 in. diam.). The bottom layer of the column consisted of a homogeneous mixture of celite (5 g) and 10 ml 1% perchloric acid. The column was eluted with 300 ml anhydrous ether. The ether eluate was evaporated to dryness. GC/MS analysis indicated the presence of (j[-i) (M at m/e 397). GC quantitation established its purity as 94.7%. Elution of the celite column with 300 ml water-washed chloroform followed. The chloroform eluate was evaporated to dryness and analyzed by GC/MS. The major constituent was heroin (M at m/e 369), as well as several other minor products, b) 3,6,17-Triacetyl-dQ normorphine (I-m). Morphine N-oxide (10 mg) was dissolved in 5 ml acetic anhydride- 0 and heated at reflux temperature for one hour. The reaction mixture was worked up by the procedure described above for 3,6,17-jriacetylnormorphine (1 -1). 3,6,17-Triacety 1-dq-nor-morphine (M at m/e 406) was obtained in the ether eluate from a 1% perchloric acid-celite column and was analyzed by GC/MS. T e major constituent from the chloroform eluate was heroin- 0 (M at m/e 375). 

Possibility A is soluble in the organic phase (methylene chloride). It hydrolyzes to the enolate salt in the aqueous-phase film at the liquid-liquid interface, as shown in Figure 13-22, and then becomes soluble in the aqueous phase as the enolate salt. A reaction system with simultaneous contacting of the two phases and extraction of the product could be feasible. The relative rates of hydrolysis and base decomposition would determine the feasibility of the system proposed. These rates were measured independently and the ratio was found to be sufficiently favorable (kRi/kR2 > 100) to proceed with design. 

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