Reactor catalytic distillation

In response to this limitation, several processes have been developed that suppress catalyst deactivation through the use of slurry reactors, catalytic distillation, and an FCC-style fluidized bed with constant catalyst regeneration (6-8). These reactors achieve high I/O ratios and lower catalyst deactivation rates, but at a cost. Fluidized beds, for example, require specialized, attrition-resistant catalyst and extensive filtration equipment. 

Process. As soHd acid catalysts have replaced Hquid acid catalysts, they have typically been placed in conventional fixed-bed reactors. An extension of fixed-bed reactor technology is the concept of catalytic distillation being offered by CR L (48). In catalytic distillation, the catalytic reaction and separation of products occur in the same vessel. The concept has been appHed commercially for the production of MTBE and is also being offered for the production of ethylbenzene and cumene. 

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. 

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). 

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... 

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. 

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 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... 

Membrane reactors [25] and catalytic distillation [26] are two options for even closer integration of isomerization and separation. The membrane concept is... 

Another multiphase reactor that achieves reaction with separation is catalytic distillation. In this reactor a catalyst is placed on the trays of a distillation column or packed into a distillation column, as shown in Figure 12-18. 

Figure 12-18 Catalytic distillation reactor in which catalyst in the distil- t. lation column combines chemical reaction with vapor-liquid equilibrium in the column to achieve conversions higher than obtainahle with a reactor alone.

The catalytic distillation reactor is in effect a multistage reactor, where each tray achieves equilibririm at its temperature and composition, with the temperature being lower at the top, where there is more B and higher at the bottom, where there is more C. With a high reflux ratio in the condenser to return any or C to the column, one can attain essentially complete reaction and separation of the products from each other. 

As with the catalytic distillation reactor, the chromatographic reactor functions as a multistage reactor. The chromatographic reactor is essentially a batch reactor, and we need to adapt this configuration into a continuous process to develop a large-scale and economic process. 

By comparison, the catalyzed transesterification reaction between ethylene carbonate and methanol (Equation 7.3) offers an alternative for greening DMC production. In this Asahi Kasei process [27], the preferred catalyst is based on an anion-exchange resin operating under catalytic distillation conditions between 333-353 K. This reactor design shifts the thermodynamic equilibrium towards complete conversion of ethylene carbonate, such that both the yield and selectivity for DMC and monoethylene glycol are 99.5%. The process is capable of supplying monoethylene glycol to the market, and DMC for captive use to produce DPC. 

Fixed-bed catalytic reactors and reactive distillation columns are widely used in many industrial processes. Recently, structured packing (e.g., monoliths, katapak, mella-pak etc.) has been suggested for various chemical processes [1-4,14].One of the major challenges in the design and operation of reactors with structured packing is the prevention of liquid flow maldistribution, which could cause portions of the bed to be incompletely wetted. Such maldistribution, when it occurs, causes severe under-performance of reactors or catalytic distillation columns. It also can lead to hot spot formation, reactor runaway in exothermic reactions, decreased selectivity to desired products, in addition to the general underutilization of the catalyst bed. 

Smith LA Jr, Arganbright RP, Hearn D. Preparation of ethylbenzene in a catalytic distillation column reactor. U.S. Patent 5,476,978, Chemical Research and Licensing Company, 1995. 

Zeolite Reactor 3-DDM Fixed bed MCM-22 Fixed bed Y Catalytic distillation Beta Fixed bed Beta Fixed bed... 

The CDTECH alkylation reactor consists of two main sections—a catalytic distillation section and a standard distillation section—as shown in Fig. 6. Benzene is fed to the top of the alkylation reactor and ethylene is fed as a vapor below the catalytic distillation section, creating a countercurrent flow of... 

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