Catalyst – solid sorbent – or support therefor: product or process – Solid sorbent – Aluminum containing
Reexamination Certificate
1997-11-17
2002-11-12
Ghyka, Alexander (Department: 2812)
Catalyst, solid sorbent, or support therefor: product or process
Solid sorbent
Aluminum containing
C502S341000, C502S342000, C502S424000
Reexamination Certificate
active
06479429
ABSTRACT:
BACKGROUND
This invention relates to the field of sorbent compositions.
This invention relates to the field of particulate compositions.
Fluidized bed reactors have advantages over fixed bed reactors such as better heat transfer and better pressure drop. Fluidized bed reactors generally use reactants that are particulates. The size of these particulates is generally in the range of about 1 to about 1000 microns. However, the reactants used generally do not have sufficient thermal stability and sufficient attrition resistance for all applications.
The removal of sulfur from fluid streams has long been desirable, as well as necessary, for a variety of reasons. If a sulfur-containing-fluid-stream is to be released as a waste stream, removal of such sulfur from the fluid stream is often necessary to meet certain environmental regulations. If a sulfur-containing-fluid-stream is to be used in a catalytic process, removal of such sulfur is often necessary to prevent catalyst poisoning. Sulfur-containing-fluid-streams are sometimes used in fluidized bed reactors. Fluidized bed reactors have advantages over fixed bed reactors such as better heat transfer and better pressure drop. Fluidized bed reactors generally use reactants that are particulates. The size of these particulates is generally in the range of about 1 to about 1000 microns. However, the reactants used generally do not have sufficient thermal stability and sufficient attrition resistance for all applications. Consequently, finding a sorbent that removes sulfur from these fluid streams and that can be used in fluidized bed reactors is desirable.
SUMMARY
It is an object of this invention to provide a process to produce a particulate composition.
It is another object of this invention to provide a process to produce a particulate composition that has improved thermal stability and improved attrition resistance and that can be used in a wide variety of applications.
In accordance with this invention a process is provided to produce a particulate composition that comprises zinc aluminate. This process comprises: (a) contacting a zinc component, an alumina component, a dispersant component, to form a mixture, and the (b) spray drying said mixture to form said particulate composition.
It is an object of this invention to provide a process to produce a sorbent composition.
It is another object of this invention to provide a process to produce a sorbent composition that has improved thermal stability and improved attrition resistance and that can be used in fluidized bed reactors.
In accordance with this invention a process is provided to produce a sorbent composition. This process comprises: (a) contacting a zinc component, an alumina component, and a dispersant component, to form a mixture; and then (b) spray drying said mixture to form particles; and then (c) contacting said particles with a zinc compound, wherein said zinc compound is zinc oxide, or it is a compound convertible to zinc oxide, to form a sorbent composition.
DETAILED DESCRIPTION OF THE INVENTION
Generally, the zinc component is zinc oxide. However, it may be any zinc compound that combines with alumina to form zinc aluminate under the conditions of preparation described herein. Examples of such compounds include, but are not limited to, zinc sulfide, zinc sulfate, zinc hydroxide, zinc carbonate, zinc acetate, zinc nitrate, zinc chloride, zinc bromide, zinc iodide, zinc oxychloride, and zinc stearate. Mixtures of such compounds can also be used. The amount of the zinc component used is in the range of about 5 to about 75 weight percent based on the total weight of the components. However, an amount in the range of about 15 to about 60 weight percent is preferred and an amount in the range of about 25 to about 45 weight percent is most preferred.
The alumina component can be any suitable alumina or aluminosilicate. The alumina component should combine with the zinc component, under the conditions of preparation herein, to form zinc aluminate. Suitable alumina components include, but are not limited to, hydrated alumina and flame-hydrolyzed alumina. The amount of the alumina component used is in the range of about 5 to about 90 weight percent based on the total weight of the components. However, an amount in the range of about 25 to about 75 weight percent is preferred and an amount in the range of about 40 to about 65 weight percent is most preferred.
The dispersant component can be any suitable compound that helps to promote the spray drying ability of the mixture. In particular, these components are useful in preventing deposition, precipitation, settling, agglomerating, adhering, and caking of solid particles in a fluid medium. Suitable dispersants include, but are not limited to, condensed phosphates and sulfonated polymers. The term condensed phosphates refers to any dehydrated phosphate where the H
2
O:P
2
O
5
is less than about 3:1. Specific examples of suitable dispersants include, but are not limited to, sodium pyrophosphate, sodium metaphosphate, and sulfonated styrene maleic anhydride polymer. The amount of the component used is in the range of about 0.01 to about 10 weight percent based on the total weight of the components. However, an amount in the range of about 0.1 to about 8 weight percent is preferred and an amount in the range of about 1 to about 3 weight percent is most preferred.
In a preferred embodiment of the invention a binder component is used. The binder component can be any suitable compound that has cement-like properties, or clay-like properties, which can help to bind the particulate composition together. Suitable examples of such binder components include, but are not limited to, cements such as, for example, gypsum plaster, common lime, hydraulic lime, natural cements, portland cements, and high alumina cements, and clays, such as, for example, attapulgite, bentonite, halloysite, hectorite, kaolinite, montmorillonite, pyrophylite, sepiolite, talc, and vermiculite. A particularly preferred binder component is calcium aluminate cement. The amount of binder component used is in the range of about 0.1 to about 30 weight percent based on the total weight of the components. However, an amount in the range of about 1 to about 20 weight percent is preferred and an amount in the range of about 5 to about 15 weight percent is most preferred.
In another preferred embodiment of the invention an acid component is used. The acid component can be any suitable acid that can help form zinc aluminate from the zinc component and the alumina component. In general, the acid component can be an organic acid or a mineral acid. If the acid component is an organic acid it is preferred if it is a carboxylic acid. If the acid component is a mineral acid preferably it is a nitric acid, a phosphoric acid, or a sulfuiric acid. Mixtures of these acids can also be used. Generally, the acid is used with water to form a dilute aqueous acid solution. The amount of acid in the acid component is in the range of about 0.01 to about 20 volume percent based on the total volume of the acid component. However, it is preferred if the amount is in the range of about 0.1 to 10 volume percent and it is most preferred if the amount is in the range of about 1 to about 5 volume percent. In general, the amount of acid component to use is based on the amount the dry components. That is, the ratio of all the dry components (in grams) to the acid component (in milliliters) should be less than about 1.75:1. However, it is preferred if this ratio is less than about 1.25:1 and it is more preferred if it is less than about 0.75:1. These ratios will help to form a mixture that is a liquid solution, a slurry, or a paste that is capable of being dispersed in a fluid like spray.
The zinc component, alumina component, and dispersant component can be contacted together in any manner known in the art that will form a mixture that is a liquid solution, a slurry, or a paste that is capable of being dispersed in a fluid like spray. When the zinc component, alumina component, and dispersant compon
Ghyka Alexander
Phillips Petroleum Company
Richmond, Hitchcock, Fish & Dollar
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