WO1998050328A1

WO1998050328A1 - Method for oxichlorination of ethylene in a fluidized bed-catalyst bed

Info

Publication number: WO1998050328A1
Application number: PCT/EP1998/002087
Authority: WO
Inventors: Michael Benje
Original assignee: Krupp Uhde Gmbh
Priority date: 1997-05-03
Filing date: 1998-04-09
Publication date: 1998-11-12
Also published as: AU7642498A; DE19718871A1

Abstract

The invention relates to a method for oxichlorination of ethylene, wherein the heat arising from a catalytic reaction is eliminated in a catalyst bed which is configured as a fluidized bed via a bundle of heat exchanger tubes immersed therein. The catalyst material forming the fluidized bed is diluted with an inert material forming the catalyst carrier and/or with a ceramic material exhibiting high heat conductivity in order to homogenize heat transfer along the entire fluidized bed. Said method simplifies the process and reduces the cost of heterogeneous, catalytic gas phase reaction in fluidized bed reactors, more specifically in the oxichlorination of ethylene.

Description

"Process for Oxychlorination of Ethylene in a Fluidized Bed Catalyst Bed"

The invention is directed to a process for the oxychlorination of ethylene in a fluidized bed catalyst bed.

A problem with both exothermic and endothermic catalytic processes is that at the beginning of the catalyst bed the main part of the reaction and (for example in exothermic processes) the main amount of heat takes place, which then has to be dissipated to the outside, while over the rest of the bed height the Residual conversion takes place with significantly less heat. Then the heat exchanger tubes, but also the height of the catalyst layer must be designed accordingly. Since the length of the evaporator tubes must be washed around by the entire fluidized bed in order to enable sufficient heat dissipation, a large amount of catalyst is required, which is associated with correspondingly high costs.

From DD-86 387 a silicon carbide is known as a diluent for a catalyst bed. Since silicon carbide has considerable hardness, damage to the reactor or cyclones can occur in an industrially operated reactor, and increased wear of the actual catalyst, a disadvantage which must be avoided. Dilution tests in a fixed bed reactor are known from US Pat. No. 5,202,511, without giving any indication of special fluidization properties, abrasion properties and use in commercially operated fluidized bed reactors.

Constructions of heat exchanger elements are shown, for example, in DE-43 05 001-A1 or DE-41 31 446-A1.

In order to achieve a uniform temperature between the foot and the head of the fluidized bed, it has already been proposed to use glass, clay or silica or quartz to stabilize the particle size distribution of the catalyst (DE-24 42 182-C3).

This is where the invention comes in, which has set itself the task of reducing, in particular, the effort and costs involved in heterogeneous, catalytic gas-phase reactions in the fluidized bed reactor, namely in the oxychlorination of ethylene. This goal is solved by the measure of claim 1.

The material used here, which forms the catalyst carrier, has particular advantages because its physical parameters are very similar to the catalyst. This allows the parameters such as grain size, abrasion resistance and. Like., Adjust in a simple manner so that, for example, the Have abrasion losses minimized.

US Pat. No. 4,446,249 discloses a γ-alumina as a catalyst support, the dilution problem, as is the focus of the present invention, is not mentioned there.

In general, it can be said that the production of 1,2 dichloroethane (1,2-EDC) by oxychlorination of ethylene takes place on a copper-containing catalyst (carrier: aluminum oxide) according to the gross equation:

C, H ₄ + 2 HC1 + 1/2 0, C ₂ H _A C1 ₂ + H ₂ 0 + Δ H,

where the reaction is carried out in a fluidized bed reactor with heat dissipation through a vertical evaporator tube bundle. Some data may be mentioned as an example:

Bed height: approx. 14 m

Average catalyst particle diameter: approx. 51 μm

Copper content of the catalyst: approx. 4%

Reaction temperature: 220 ° C

Reaction pressure: 4.55 bar

Gas velocity with minimal fluidization: approx. 0.002 m / s

Empty tube gas velocity in the reactor: 0.21-0.42 m / s Further refinements result from the subclaims.

As already stated above, it is particularly advantageous if the inert catalyst, namely γ ~ aluminum oxide, is used as the dilution material.

It is also convenient to determine the shape of the particles e.g. choose the sphericity (deviation of the catalyst particles from an ideal spherical shape) as is the case with the catalyst particles themselves, a catalyst and a corresponding dilution material with a sphericity of 0.99 being used expediently (almost ideal Spherical shape). Such round particles ideally reduce unwanted abrasion.

According to the invention, a grain size distribution is also selected for the dilution material which corresponds to that of the catalyst material itself, this also promotes the reduction in the abrasion behavior, so that the amount of fine dust discharged is not changed compared to conventionally operated systems.

An expedient variant of the invention is that dilution material made of ceramic with high thermal conductivity is used. The use of highly porous γ-alumina as a diluent promotes the formation of by-products which can be influenced by these diluents, so that the invention also suggests the use of γ ~ alumina with a low surface area, but with the discharge and abrasion properties of the original catalyst. This also applies to a variation in acidity through appropriate doping.

In general it should be noted that the process can also be used in other fluidized bed processes; it does not necessarily have to be used for the oxychlorination of ethylene, although it is of particular value here. The thermal conductivity of the inert material used has a significant influence on the jacket-side heat transfer coefficients. Ceramic materials can be used here in a special way, which further increases the efficiency of the catalyst dilution process.

In addition to the particularly advantageous amount of up to 50% γ-aluminum oxide as a diluent, it should be noted that other mixing ratios are also possible here. Depending on the field of application, a higher proportion of the dilution material can also be provided.

Claims

Claims:

1. A process for the oxychlorination of ethylene, the heat generated in a catalytic reaction being dissipated in a fluidized bed catalyst bed via heat exchanger tube bundles immersed therein, and the catalyst material forming the fluidized bed, in particular for equalizing the heat transfer over the height of the fluidized bed and for reducing it of abrasion volume, is diluted with an inert material forming the catalyst support and / or with a ceramic material with high thermal conductivity.

2. The method according to claim 1, characterized in that γ-alumina is used as the dilution material.

3. The method according to claim 1 or 2, characterized in that the catalyst material is diluted up to 50% with γ-aluminum oxide.

4. The method according to any one of the preceding claims, characterized in that highly porous γ-aluminum oxide as a diluent for Favoring the formation of by-products is used, the discharge and abrasion properties corresponding to those of the catalyst used.

5. The method according to any one of the preceding claims, characterized in that in order to optimize the transmission properties by doping, the acidity of the dilution material is varied.

6. The method according to any one of the preceding claims, characterized in that dilution material particles are used to reduce the abrasion in the most ideal spherical shape.