JP2002263476A - Method of equalizing heat distribution in reactor tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of equalizing heat distribution in a reactor tube housing a catalyst. SOLUTION: When a catalyst monolith is used, reaction heat can be dispersed as desired and consequently a heat gradient is lowered and efficiently and catalyst performance are improved. The method of equalizing the heat distribution on the catalyst of the tubular reactor is provided and this method comprises packing >=1 catalytic monolith into the respective tubes of the tubular reactor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for equalizing heat distribution in a reaction tube containing a catalyst.

[0002]

BACKGROUND OF THE INVENTION The performance of a constant temperature tube reactor packed with catalyst is limited by heat transfer in the catalyst packed tube.
In an endothermic reaction, heat is removed from the center of the tube and the temperature at the tube wall is substantially higher than at the tube center. In an exothermic reaction, the heat of reaction causes the temperature of the catalyst in the central zone of the catalyst bed to be substantially higher than the temperature in the outer region of the catalyst bed near the tube wall. Various adverse effects may occur due to the temperature difference. The cold part of the filling may remain too low for effective contact treatment, and the hot part of the filling may have a shorter life than expected. In either case, processing efficiency is reduced.

[0003] Heat transfer problems reduce the efficiency of isothermal reactors and their commercial appeal as compared to adiabatic systems. This is especially true for endothermic systems that require high tube wall temperatures in a thermostatic reactor to provide sufficient heat to the center of the tube, resulting in high temperature gradients and non-optimal performance.

[0004]

SUMMARY OF THE INVENTION With the use of a catalytic monolith, heat can be directed in the desired direction, thus reducing thermal gradients and improving efficiency and catalytic performance. A method is provided for equalizing the heat distribution on a catalyst in a tubular reactor, the method comprising charging each tube of the tubular reactor with one or more catalytic monoliths.

[0005]

DETAILED DESCRIPTION "Monolith catalyst" means a catalyst comprising a conventional ceramic support having unidirectional or multidirectional channels. The support may be impregnated with one or more catalytically reactive metals, or the support material itself may be a catalytically reactive material (eg, iron oxide) or may include a catalytically reactive material. . Monolithic catalysts have the advantage that they can be formed in a shape close to that of a container. Therefore,
Monolithic catalysts for tubular reactors may be sufficiently long (several inches to several feet long) cylindrical and usually have a diameter slightly smaller than the inside diameter of the tube in which the monolithic catalyst is located.
Unidirectional or multidirectional channels can be formed into a monolith so that the feed flows as desired. In this way,
Each channel has a surface area equal to many loose catalyst particles.

[0006] The surfaces of the channels may be impregnated with a catalytically active metal or metal compound to render each channel effective as a catalyst having a surface area equal to the surface area of the channel. Alternatively, the monolith may be composed of a catalytically reactive material.

[0007] The heat distribution on the catalyst in a tubular reactor is equalized by directing heat as desired downward to the channels of the monolith catalyst packed in the tubes of the tubular reactor. The heat may be directed inward to equalize the temperature profile of the tubes of the endothermic reactor or outward to equalize the temperature profile of the tubes of the exothermic reaction.

[0008] The monolithic catalyst used as described above has another advantage in that the pressure drop in the catalyst bed is suppressed.

The process according to the invention is used in particular in a commercial thermostatic reactor for the production of styrene by the endothermic dehydrogenation of ethylbenzene. The reactor has three major problems: the liquid space velocity must be low for the reaction, and a larger diameter tube is required. Since the styrene reaction is an endothermic reaction, heat must be applied, and in large tubes the temperature difference from the outside of the tube to the center of the catalyst bed is large, resulting in poor catalyst performance. Furthermore, as the temperature of the tube wall is increased to apply heat to the center of the fill, the temperature of the tube wall can reach levels at which ethylbenzene and styrene can decompose and thus produce undesirable by-products; Isothermal reactors exhibit a substantially higher pressure drop compared to radial adiabatic reactors. For this reason, tubular reactors are disadvantageous in terms of activity and selectivity; one mole of feed (ethylbenzene) is converted to product (styrene +
(Hydrogen) 2 mol, so that the above-mentioned problem becomes remarkable.

With the use of monolith catalysts, heat is directed to the center of the catalyst bed in each tube, reducing the temperature of the tube walls and reducing the decomposition of feedstock and products into unwanted by-products. The resulting pressure drop is also advantageous for the styrene reaction.

The monolithic catalysts described above are useful for controlling the tube temperature profile of other endothermic reactions (eg, dehydrogenation and olefin cracking processes).
The monolith catalyst may be modified to radiate heat from the center of the reaction tube through the channel and thus be useful for exothermic reactions such as epoxide gas phase production, other oxidation methods and hydrocracking methods.

It will be apparent to those skilled in the art that many changes and modifications can be made to the present invention without departing from the spirit or scope of the invention described herein.

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Claims (5)

[Claims] 1. A method for equalizing heat distribution on a catalyst in a tubular reactor, wherein each tube of the tubular reactor is filled with one or more catalyst monoliths. 2. The method according to claim 1, wherein the catalytic monolith comprises a ceramic monolith support impregnated with one or more catalytically reactive metals. 3. The catalyst monolith contains iron oxide useful for catalytic dehydrogenation of ethylbenzene to styrene, and the channels in the catalyst monolith are arranged so that heat is directed toward the center of each tube. The method of claim 1, wherein 4. The catalyst-reactive metal is selected from the group consisting of nickel, cobalt and molybdenum, wherein the catalyst monolith is useful for hydrocarbon dehydrogenation and the heat in the catalyst monolith is such that heat is directed to the center of each tube. 3. The method according to claim 2, wherein the channels are arranged. 5. The method of claim 1, wherein the catalytically reactive metal is silver, the catalytic monolith is useful for the vapor phase production of epoxides, and the channels in the catalytic monolith are arranged so that heat leaves the center of each tube. 3. The method according to claim 2, wherein the method comprises: