JP3361831B2 - Method for deagglomerated and re-exposed catalyst in fluidized bed reactor - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method of enhancing the performance of fluidized bed catalysts which have lost their activity or fluidity characteristics due to surface contaminants or other physical or chemical changes on the catalyst.
In particular, the present invention relates to a method of polishing a catalyst surface in use to remove a thin layer of the catalyst surface, thereby exposing new catalyst.

[0002]

2. Description of the Prior Art In a fluidized bed catalytic reactor, solid particles of finely divided catalyst are
Typically contacted with a vaporous reaction medium. The term "fluidized bed" is used because the catalyst particles are lifted and agitated by the ascending flow of product gas and the catalyst particles are suspended in the gas stream and resemble a boiling liquid.

One of the earliest and best-known applications of fluid bed reactor technology was the catalytic cracking of petroleum to produce gasoline and other light hydrocarbons. Other uses include coking of residues, gasification of coke, catalytic oxidation of benzene or butane to maleic anhydride, ammoxidation of propylene to acrylonitrile, oxidation of hydrogen chloride to chlorine.

The present invention focuses on the catalysts used in fluidized bed reactors. Through repeated use, the fluidized bed catalyst undergoes physical or chemical changes to the less catalytically active form, either because the surface of the catalyst is fouled by contaminants or byproducts generated by the reaction. So lose activity. Furthermore, when contaminants or physical or chemical changes occur on the surface of the catalyst, the catalyst becomes "sticky" and the small fluid bed particles begin to agglomerate into larger particles. Aggregated particles cause a reduction in catalyst surface area, thereby affecting the overall performance of the fluidized bed catalyst. Furthermore, the agglomerated particles hinder the natural circulation and fluidization of the catalyst bed.

Typically, the solution to the above problem is to replace all or part of the catalyst in the fluidized bed reactor.
This is very costly in terms of catalyst cost and cost of production down resulting from shutting down the fluidized bed reactor containing the catalyst exchange. The object of the present invention described here is a method for solving the problems caused by agglomeration, fouling or physical or chemical changes on the surface of the catalyst, so as to extend the life of the catalyst.

[0006]

A method of deflocculating a fluidized bed catalyst to re-expose the surface of the fluidized bed catalyst which has lost its activity or fluidity due to contaminants or physical or chemical changes on the surface of the catalyst. Has been discovered. The process is carried out inside an operating fluidized bed reactor, but it can alternatively be carried out outside the reactor in a continuous or discontinuous manner.

In the preferred embodiment, the process comprises providing the fluidized bed reactor with at least one injection nozzle through which gas is supplied from a source external to the reactor. The injection nozzle is positioned inside the reactor such that the nozzle is embedded in the catalyst bed and the gas exiting the nozzle is in immediate contact with the catalyst. The gas exits the nozzle at a sufficient rate of discharge and contacts the fluidized fluidized bed catalyst particles, causing many collisions between the catalyst particles. The impact of multiple collisions of catalyst particles causes the surface of the catalyst to be abraded, thereby removing contaminants on the surface of the catalyst or materials that have lost catalytic function and exposing new catalyst.

A fluidized bed reactor is any reaction vessel in which a gas-solid or liquid-solid contact process takes place. In the reactor, a bed of finely divided solid particles (ie fluidized bed catalyst) is lifted and separated by using a product gas stream or a liquid stream. Fluidized bed reactors come in all shapes and sizes. Typically the reactor comprises a grid near the bottom of the reactor, which grid
The catalyst bed is supported while passing the product gas. The remainder of this description focuses on the practice of the invention in a gas-solid contact process. However, the methods described herein are equally applicable to liquid-solid contact processes.

In the gas-solid contact process, the process product gas exits the top of the reactor. Typically,
Since the produced gas carries the catalyst particles, the produced gas flows through the separator to take out the catalyst particles, and the catalyst particles are returned to the catalyst layer through the dipleg. The separator may be any solid recovery device, such as a cyclone and a filter.

Fluid bed catalysts are finely divided solid particles that vary in size, weight and composition depending on the application. Macroscopically, fluid bed catalysts very often resemble powders. However, macroscopically, such catalysts
It looks like a small bead. Fluid bed catalyst particles typically range in size from 10 microns to 200 microns. In some applications, the effectiveness of fluidized bed catalysts depends on the formation of contaminants or physical or chemical changes on the surface of the catalyst.
Lost. This condition causes a decrease in the activity of the catalyst or causes the catalyst to "stick", in which case the catalyst particles tend to agglomerate, thereby
It loses both in flow properties and / or catalyst activity.

In the practice of the present invention, the fluidized bed reactor is internally equipped with one or more injection nozzles for supplying high velocity gas to the catalyst bed. During the practice of the present invention, the catalyst is maintained under fluidized conditions (ie, fluidized) caused by an upflow of product gas or other gas, the upflow lifting and agitating catalyst particles Float inside.
Due to the force of the gas flow, the fluidized catalyst particles collide many times, and the impact caused by the collision of the catalyst particles is
Polish the catalyst surface to remove any contaminants on the surface,
Expose the new catalyst. Further, the impact caused by the collision of the catalyst particles causes the agglomerated catalyst particles to deagglomerate (ie, break apart). The present invention may also be practiced in vessels equipped with any device (such as a nozzle or a gas distribution grid or a plate with one or more holes) that achieves contact between a high velocity gas stream and fluidized catalyst particles. You can

The present invention is preferably practiced in a fluidized bed reactor equipped with one or more nozzles. The nozzles used here can be of any shape or size and create any "spray pattern". The nozzle may be as simple as an open ended pipe, or it may be a short tube ending in a taper or taper to accelerate or direct the flow of gas exiting the tube. The size of the orifice is not critical to the practice of the invention. Small diameter orifices of 0.0406 cm (0.016 inch) diameter (for gas distribution grids, have 0.016 inch diameter adjustment holes) have been employed. Typical orifice sizes range from 0.1588 centimeters (0.0625 inches) to 0.
It is 635 cm (0.250 inches). More traditional orifice sizes are 0.3175 cm (0.125 in) and 0.
It is between 4763 cm (0.1875 inches). The size of the nozzle orifice is preferably 9/64 or 5/32 in diameter.

The rate of release of the gas must be such that the catalyst particles collide with each other many times with sufficient force to polish the surface of the catalyst. Hard catalysts typically require higher release rates. Emission rates up to the speed of sound can be used. The nozzle orifice and gas flow rate are sized to match the gas velocity to be used. The preferred gas velocity is in the range of 200 fps. To 1200 fps. More preferable gas speeds are 600 fps. And 1100 fps.
Is in between. Gas velocity is the "contact zone" between gas and catalyst
However, it is preferable that it extends a few inches from the front of the nozzle toward the catalyst layer. The nozzles may be oriented to impart a co-current, counter-current, counter-current, high velocity gas flow to the fluidizing product gas. The nozzles are preferably oriented to provide a co-current high velocity gas stream for fluidizing product gas.

The one or more nozzles are
It may be located anywhere in the catalyst bed that can contact the fluidized catalyst particles. For example, the nozzle may be located just inside the reactor wall or in the center of the reactor. To maximize the effectiveness of the present invention, the nozzle should be placed inside the reactor where the catalyst circulation is maximized. This maximizes the total loading of catalyst in contact with the gas. Therefore, the injection nozzle
It is preferably located adjacent to, or near, the opening of the dipleg (ie, the point of entry of the catalyst that is returned from the separator to the reactor). The collision of the catalyst with the reactor element is likely to break the catalyst, and repeated collisions damage the reactor element so that the gas flowing out of the nozzle is
Care should be taken to ensure that the catalyst does not pass towards the internal components of the reactor. The fast gas may be an inert or liquid containing gas or vapor useful for the process. Typically, this gas is supplied to the nozzle from a source external to the reactor. If a fluidized bed reactor is used for the oxidation reaction, air is typically used. But,
It is also possible to use an inert gas such as nitrogen or a reaction feed gas. In practicing the invention in commercial scale reactor operation (ie, production), the increase in total gas throughput is negligible.

The process of deagglomeration of the catalyst and / or the process of re-exposing the surface of the catalyst is
It is carried out intermittently or continuously depending on the nozzle parameters such as the nozzle position and the discharge rate of the gas flowing out from the nozzle. Contaminants or less catalytic materials on the surface of the catalyst that have been polished with the catalyst are typically removed from the reactor with the reactor effluent and then suitable separation means (eg, cyclone device, filter, etc.). Is separated from the reaction product. The key to practicing the present invention is the beneficial effect of re-exposing the catalyst surface and / or the regulation of gas velocity and nozzle placement to maximize catalyst deagglomeration, while minimizing catalyst loss. In order to achieve this, the polishing amount on the catalyst surface is minimized.

[0016]

Embodiments of the present invention are shown in the drawings. A bed of fluidized bed catalyst 2 is inside the fluidized bed reactor 1. The generated supply gas is
It enters the reactor through line 3 and flows through the gas distribution grid 4 into the catalyst bed. The vaporous reaction product containing the entrained catalyst particles flows into the cyclone 6, where the reaction product and the catalyst are separated. The vaporous reaction product exits the reactor through line 5. The catalyst is returned to the catalyst layer 2 through the dipleg 7. The fast gas is fed to the reactor through line 8 and is directed through nozzle 9 towards the catalyst bed.

The present invention has utility in any catalytic fluidized bed process in which the catalyst surface becomes contaminated by reaction by-products or by physical or chemical changes in the catalyst composition. In such situations, the catalyst loses activity and / or flow properties. Polishing the surface of the catalyst to expose new catalyst or to deagglomerate the catalyst restores activity and / or flow properties and extends catalyst life. A typical process that employs the present invention is
Catalytic cracking of petroleum to produce gasoline and other light hydrocarbons, coking of residues, gasification of coke, catalytic oxidation of benzene or n-butane to maleic anhydride, ammoxidation of propylene to acrylonitrile, and hydrogen chloride. Of chlorine to chlorine.

As described herein, the high velocity gas is contacted with the fluidizing catalyst inside the reactor during operation. The present invention can also be implemented by placing the nozzle inside the dipleg. Further, when the fluidized bed reactor is equipped with a regenerator to remove the catalyst to be treated, i.e. reactivated and returned to the reactor, the catalyst surface is reexposed and / or the catalyst is As explained, the catalyst is deflocculated inside the regenerator or inside the catalyst transfer line between the reactor and the regenerator. Finally, the present invention also
It can be carried out by removing the catalyst from the reactor, re-exposing the catalyst surface, and / or deflocculating the catalyst as described herein, and then returning the catalyst to the reactor.

The above description is not exhaustive and is not limited to the precise forms disclosed, and many variations and changes are clearly possible in light of the above disclosure. The purpose of the present description is to explain the principles and practical applications of the present invention, so that the so-called person skilled in the art may make various modifications of the present invention in various embodiments and in various modifications suitable for the particular use. It is to be able to utilize the invention. The invention is defined only by the claims.

[Brief description of drawings]

1 is a schematic cross-sectional view of a fluidized bed reactor illustrating an embodiment of the present invention.

[Explanation of symbols]

1 fluidized bed reactor 2 fluidized bed catalyst 3 pipelines 5 pipelines 9 nozzles

Front Page Continuation (72) Timothy Robert McDonnell 44141 Brexville Crestview Drive 6985 (56) References JP 55-67335 (JP, A) JP 37-15762 (JP, B1) (58) ) Fields surveyed (Int.Cl. ⁷ , DB name) B01J 38/00 C07C 255/08 C07D 307/60

Claims (8)

(57) [Claims] 1. A method for deagglomerating a fluidized bed catalyst particle which is contaminated on the surface or undergoes physical or chemical changes during use in the production of acrylonitrile or maleic anhydride, or a surface of the fluidized bed catalyst particle. At least one method of re-exposure, wherein the fluidized bed catalyst particles under fluidized conditions are between 60.96 meters (200 feet) and 365.76 meters (1200 feet) per second;
Multiple collisions between the catalyst particles with sufficient impact to coagulate the fluidized bed catalyst particles or polish the surface of the catalyst particles to remove the contaminated surface or the altered surface. Contacting with a gas having a velocity sufficient to cause 2. The method of claim 1, wherein the gas is air or nitrogen. 3. The method of claim 1, wherein the method can be carried out in a vessel equipped with a device for contacting the gas stream with the fluidized catalyst. 4. A method of deagglomerating a fluidized bed catalyst particle which is contaminated or is subjected to physical or chemical changes during use in the production of acrylonitrile or maleic anhydride. At least one of the re-exposure methods comprising: (a) maintaining the catalyst particles in the fluidized bed reactor under fluidized conditions, wherein the fluidized bed reactor is At least one injection nozzle supplied from an external source is provided, wherein the nozzle is embedded in the catalyst particles, and the gas flowing out of the nozzle is directly contacted with the catalyst particles. Positioned inside the reactor, (b) allowing gas to flow out of the nozzle at a discharge rate of 60.96 meters (200 feet) to 365.76 meters (1200 feet) per second through the fluidized bed contact. Between the catalyst particles with sufficient impact to deagglomerate the media particles or polish the surface of the catalyst particles to provide sufficient impact to remove the contaminated surface or altered surface. How to make a collision. 5. The method according to claim 4, wherein the gas is air or nitrogen. 6. The fluidized bed reactor comprises a cyclone that separates the catalyst from the gaseous effluent stream, the cyclone having a dipleg that returns the catalyst to the reactor,
The method of claim 4, wherein the nozzle is located near a catalyst outlet from the dipleg. 7. The method of claim 4 wherein the process of re-exposing the catalyst surface is performed while the fluidized bed reactor is producing maleic anhydride or acrylonitrile during operation. The method described. 8. The nozzle orifice opening has a diameter of 0.31
The method of claim 4, wherein the method is between 75 cm (0.125 inch) and 0.4763 cm (0.1875 inch).