Distillation, catalytic

The second new zeoHte-basedhquid-phase process was developed by Chemical Research licensing Company (CR L). The process is based on the concept of catalytic distillation, ie, reaction and separation in the same vessel. The concept has been appHed commercially for the production of MTBE (48—51) but has not yet been appHed commercially for the production of ethylbenzene. 

Two new processes usiag 2eohte-based catalyst systems were developed ia the late 1980s. Unocal s technology is based on a conventional fixed-bed system. CR L has developed a catalytic distillation system based on an extension of the CR L MTBE technology (48—51). 

The second zeofite process, which was developed by CR L, is based on the concept of catalytic distillation (48—51), which is a combination of... 

The reactor combinations for the two reactors in series consist of two fixed-beds for the Arco process an expanded bed followed by a catalytic distillation reactor for lEP a fixed-bed followed by a catalytic distillation reactor for CDTECH and two fixed-beds for Phillips. The Huls process uses an adiabatic reactor for the second reactor. 

Catalytic Distillation Technologies, Lummus Grest, Inc., Bloomfield, N.J., 1990. 

Heterogeneous catalytic systems offer the advantage that separation of the products from the catalyst is usually not a problem. The reacting fluid passes through a catalyst-filled reactor m the steady state, and the reaction products can be separated by standard methods. A recent innovation called catalytic distillation combines both the catalytic reaction and the separation process in the same vessel. This combination decreases the number of unit operations involved in a chemical process and has been used to make gasoline additives such as MTBE (methyl tertiai-y butyl ether). 

A wealth of structures exists and can be found in the literature [1-3]. Figure 9.1 shows examples of monoliths and arrayed catalysts. MonoHths (Figure 9.1a) consist of parallel channels, whereas arrayed catalysts are built from structural elements that are similar to monolithic structures but containing twisted (zig-zag or skewed) passages and/or interconnected passages (Figure 9.1b,c) or arrays of packets of conventional catalyst particles located in the reaction zone in a structured way, whereby the position of particles inside the packets is random (Figure 9.1d). The latter are mainly used for catalytic distillation and are not discussed further in this chapter. 

Countercurrent flow has advantages in product and thermodynamically limited reactions. Catalytic packings (see Figure 9. Id) are commonly used in that mode of operation in catalytic distillation. Esterification (methyl acetate, ethyl acetate, and butyl acetate), acetalization, etherification (MTBE), and ester hydrolysis (methyl acetate) were implemented on an industrial scale. 

As mentioned earlier, a major cause of high costs in fine chemicals manufacturing is the complexity of the processes. Hence, the key to more economical processes is reduction of the number of unit operations by judicious process integration. This pertains to the successful integration of, for example, chemical and biocatalytic steps, or of reaction steps with (catalyst) separations. A recurring problem in the batch-wise production of fine chemicals is the (perceived) necessity for solvent switches from one reaction step to another or from the reaction to the product separation. Process simplification, e.g. by integration of reaction and separation steps into a single unit operation, will provide obvious economic and environmental benefits. Examples include catalytic distillation, and the use of (catalytic) membranes to facilitate separation of products from catalysts. 

In a distillation column reactor (DCR), reaction and distillation occur simultaneously. This technology is also referred to as reactive distillation, or, if a catalyst is involved, as catalytic distillation. DCRs offer distinct advantages of exploiting the exothermicity of reactions, such... 

A Catalytic Distillation Process for the One Step Synthesis of Methyl Isobutyl Ketone from Acetone Liquid Phase Kinetics of the Hydrogenation of Mesityl Oxide... 

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. 

CD-Cumene A process for making cumene for subsequent conversion to phenol and acetone. The cumene is made by catalytic alkylation of benzene with propylene in a catalytic distillation reactor. Developed in 1995 by CDTech. 

CDETHEROL A process for making ethers (MTBE, TAME, ETBE) from alcohols. Combines the Etherol process with catalytic distillation. 

CDHydro [Catalytic distillation hydrogenation] A process for hydrogenating diolefins in butylene feedstocks. It combines hydrogenation with fractional distillation. Developed by CDTECH, a partnership between Chemical Research Licensing Company and ABB Lummus Crest. The first plant was built at Shell s Norco, LA, site in 1994. Ten units were operating in 1997. 

RATAPAR Not a process but a range of catalysts and catalyst supports using the principle of static mixing. Developed by Sulzer Chemtech since 1991. Used in catalytic distillation processes. 

Additionally, the concept of catalytic SILP materials may be easily combined with several advanced process options providing new opportimities for accomplishing reactions. One attractive approach involves the conductance of consecutive, homogeneous reactions in sequences using several fixed-bed reactors in-series. Another approach involves implementation of integrated reaction-separation techniques using, e.g., SILP-membranes or the use of SILP materials in catalytic distillation processes. 

In more recent vintages of the cumene manufacture processes, zeolyte catalysts permit going directly to cumene from the same two feeds, benzene and propylene. The introduction of catalytic distillation has even further improved the process economics, a thing that delights the manufacturers. 

In a Texas two-step that has led to a more economical route for cumene, new catalysts combined with a novel processing scheme has reduced both operating costs and increased the yield of cumene from its benzene and propylene feedstocks. In Figure 7-3, the main reaction takes place in a catalytic distillation column. This piece of apparatus combines a catalyst-filled reactor with a fractionator. 

From the top of the column, the propane that always accompanies the propylene feed emerges, talcing with it some of the benzene. In a flash tank, the propane is vented, and liquid benzene is recycled. From the bottom of the catalytic distillation column come the cumene, the PIPB, and some miscellaneous heavies chat are separated in a fractionator to make cumene, of 99.9% purity. The PIPB is separated in another column and fed to a second reactor with another zeolyte catalyst bed. In there the PIPB reacts catalyti-... 

The effluent from this fixed bed reactor, both vapor and liquid, goes to the catalytic distillation column where the reaction continues, converting almost all the remaining isobutylene as the gaseous C4 s, and methanol rises through the catalyst. The catalyst in this vessel is loaded in bales, sometimes called Texas teabags. As the reaction proceeds, MTBE, a lower boiling point liquid than the C4S and methanol, drops out of die bottom of the column as a liquid. The... 

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