Catalytic distillation applications

The present economic and environmental incentives for the development of a viable one-step process for MIBK production provide an excellent opportunity for the application of catalytic distillation (CD) technology. Here, the use of CD technology for the synthesis of MIBK from acetone is described and recent progress on this process development is reported. Specifically, the results of a study on the liquid phase kinetics of the liquid phase hydrogenation of mesityl oxide (MO) in acetone are presented. Our preliminary spectroscopic results suggest that MO exists as a diadsorbed species with both the carbonyl and olefin groups coordinated to the catalyst. An empirical kinetic model was developed which will be incorporated into our three-phase non-equilibrium rate-based model for the simulation of yield and selectivity for the one step synthesis of MIBK via CD. 

This section deals with the conceptual design of a catalytic distillation process for the esterification of lauric acid (LA) with 2-ethyl-hexanol (2EtH). Laboratory experiments showed that a superacid sulfated zirconia catalyst exhibits good activity over a large interval, from 130 to 180 °C with no ether formation. On the contrary, the catalyst is sensitive to the presence of free liquid water. Raw materials are lauric acid and 2-ethylhexyl alcohol of high purity. The conversion should be over 99.9%, because the product is aimed at cosmetic applications. 

Application Advanced technology to produce high-purity cumene from propylene and benzene using patented catalytic distillation (CD) technology. The CDCumene process uses a specially formulated zeolite alkylation catalyst packaged in a proprietary CD structure and another specially formulated zeolite transalkylation catalyst in loose form. 

Application To produce ethylbenzene (EB) by alkylating benzene with ethylene using a patented ethylbenzene (EB) fixed-bed, catalytic distillation technology with a zeolite catalyst. 

Film flow is the only possible regime for applications in which countercurrent flow is intrinsic to the operation catalytic distillation is the... 

The first commercial and most well-known application of CD was in the production of MTBE. Besides etherification for the production of MTBE, CD could be applied in a number of processes such as alkylation, hydrogenation, isomerization, esterification, desulfurization, aldol condensation, oligomerization, hydration, hydrolysis, amination, and halogenation. Catalytic Distillation Technology (CDTECH), a partnership between ABB Lummus Global and Chemical Research and Licensing, is the leader in the development and commercialization of CD processes particularly related to the refining, petrochemical, and chemical industries. However, there are many more potential applications of CD that could be developed. 

Catalytic distillation hydrogenation is one of the more recent applications of CD that was commercialized by CDTECH for the selective hydrogenation of dienes in C4-C6 streams and the saturation of benzene in the... 

The oligomerization of olefins is an exothermic consecutive reaction, which benefits from the application of CD for enhanced selectivity to intermediate products. Catalytic distillation plays a particularly important role in enhancing the catalyst lifetime because in situ separation reduces the undesirable high-molecular-weight oligomers or polymers, which will form coke and deactivate the catalyst. The use of reaction heat for distillation also reduces the formation of hot spots and catalyst deactivation due to sintering. 

Catalytic distillation can also be used for selective separations such as the separation of piperidine from n-amylamine, separation of isobutylene in a C4 stream, and removal of acetic acid from dilute aqueous streams. The application of CD for separations will not be reviewed in this article. The potential use of RD for the separation of chiral compounds is very noteworthy although no corresponding CD process was reported. ... 

Catalytic distillation is a rapidly developing field with applications in many processes for the chemical, petrochemical, and petroleum industry. It is emerging as a tool for green process and technology innovations because it utilizes process intensification to achieve energy efficiency and the reduction of greenhouse gases. 

Huang, C. Yang, L. Ng, F.T.T. Rempel, G.L. Application of catalytic distillation for the aldol condensation of acetone a rate-based model in simulating the catalytic distillation performance under steady-state operations. Chem. Eng. Sci. 1998, 53 (19), 3489-3499. 

If a chemical reaction occurs inside a distillation colmnn, with reactants and products subject to the usual requirements of the distillation process (phase eqniUbria, fractionation, and contacting device hydraulics), it is possible to shift the reaction eqnilibrimn in a favorable direction. A soluble or insoluble catalyst is likely to be involved thns, the operation is often known as catalytic distillation. Reactive distillation has been nsed snccessfnlly for etherification and esterification reactions and, to some extent, for alkylation, nitration, and amidation reactions. In most applications, the reaction has occurred in the liqnid phase, and an example of this application, where methyl acetate is produced from methanol and acetic acid nsing a solnble catalyst, has been described in detail. Flows for a generalized reactive colmnn are shown in Figm-e 12.21. 

It is obvious that catalytic distillation requires a reactor dedicated to one specific type of catalytic reaction. It can be questioned whether the fine-chemical industry performs many reactions needing a dedicated reactor. Application of the catalyst as a thin porous layer on the surface of a metal or ceramic material, however, affords interesting possibilities in the fine-chemical industry. With liquid-phase reactions, the catalyst is still almost completely involved in the reaction when the layer in which the catalyst is present is not much thicker than ca 100 pm. Separation of the catalyst from the reaction product, removal of the catalyst from the reactor, and collection and storage of the catalyst is no longer required this greatly facilitates operation. The catalyst can, furthermore, be treated thermally in a gas flow, because the pressure drop depends on the structure of the solid on which the catalyst has been applied. This structure can easily be selected thus that the pressure drop is low. When, finally, the catalyst is applied to a metal surface with appreciable thermal conductivity the temperature of the reaction can be maintained accurately at the value desired. 

Housing the reaction and separation in the same unit could lead to significant savings in both capital and operation costs. Reactive (catalytic) distillation has received an increased interest in the recent years. Several industrial applications demonstrate its benefits, as shown in Chapter 7. 

A somewhat different type of distillation with reaction is catalytic distillation fPoherty et al.. 2008 Parkinson. 200S1. In this process bales of catalyst are stacked in the column. The bales serve both as the catalyst and as the column packing (see Chapter 101. This process was used commercially for production of methyl tert-butyl ether (MTBE) from the liquid-phase reaction of isobutylene and methanol. The heat generated by the exothermic reaction is used to supply much of the heat required for the distillation. Since MTBE use as a gasoline additive has been oudawed because of pollution problems from leaky storage tanks, these units are shut down. Other applications of catalytic distillation include desulfurization of gasoline, separation of 2-butene from a mixed C4 stream, esterification of fatty acids and etherification. 

If the catalytic HBr oxidation reactor is required to serve as a central facility for recycling a variety of waste HBr streams and conditions that combust all of the organic contaminants cannot be discovered, then further bromine purification operations are probably required. The simplest operation is distillation of the bromine. Due to the high bromine vapor pressure, bromine distillation can be accomplished using relatively small equipment. This is expected to be a highly effective method of purification, particularly where the boiling points of any contaminants are greater than 10°C different from that of bromine. In other applications, absorption or extraction may be needed. 

Intelligent engineering can drastically improve process selectivity (see Sharma, 1988, 1990) as illustrated in Chapter 4 of this book. A combination of reaction with an appropriate separation operation is the first option if the reaction is limited by chemical equilibrium. In such combinations one product is removed from the reaction zone continuously, allowing for a higher conversion of raw materials. Extractive reactions involve the addition of a second liquid phase, in which the product is better soluble than the reactants, to the reaction zone. Thus, the product is withdrawn from the reactive phase shifting the reaction mixture to product(s). The same principle can be realized if an additive is introduced into the reaction zone that causes precipitation of the desired product. A combination of reaction with distillation in a single column allows the removal of volatile products from the reaction zone that is then realized in the (fractional) distillation zone. Finally, reaction can be combined with filtration. A typical example of the latter system is the application of catalytic membranes. In all these cases, withdrawal of the product shifts the equilibrium mixture to the product. 

None of the alternative strategies for catalyst/product separation has yet reached the point where it can be commercialised for the rhodium catalysed hydroformyation of long chain alkenes and there are very few examples of commercialisation in any catalytic applications. Batch continuous processing with low pressure product distillation has been commercialised but the complexity of the system suggests that alternatives may be able to compete. 

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