MXPA97006185A

MXPA97006185A - Process to reactivate sorbents off

Info

Publication number: MXPA97006185A
Application number: MXPA/A/1997/006185A
Authority: MX
Inventors: P Khare Gyanesh
Original assignee: Phillips Petroleum Company
Priority date: 1996-08-14
Filing date: 1997-08-13
Publication date: 1998-02-01

Abstract

The present invention relates to a process for reactivating a deactivated sorbent of zinc oxide, to produce a reactivated sorbent, the process is characterized in that it comprises: a) contacting a deactivated sorbent with a zinc composition comprising zinc oxide, or a precursor zinc oxide, to form a composition that has come into contact, b) dry the composition that has been contacted at a temperature in the range of about 25 ° C to about 375 ° C, for a period of time in the range of about 1 minute to about 24 hours, to form a composition that has been put in dry contact, and c) to calcify the composition that has been put in dry contact, at a temperature in the range of about 400 °. C at about 800 ° C, for a period of time ranging from about 1 minute to about 24 hours, to form the reactive sorbent

Description

PROCESS TO REACTIVATE DISABLED SORBENTS The present invention relates to the field of processes that produce sorbents. In particular, this invention relates to a process for reactivating a deactivated sorbent, to produce a reactivated sorbent. The removal of sulfur from a fluid stream is desirable for a variety of reasons. If a fluid stream is to be released as a waste stream, the removal of sulfur from such a fluid stream may be necessary to meet the requirements of the sulfur emission. If a stream of fluid is to be burned as fuel, the removal of sulfur from such a fluid stream may be necessary to prevent environmental contamination. If a fluid stream is going to be processed, the removal of sulfur is often necessary to prevent the poisoning of the sulfur sensitive catalysts. Several sorbents have been used to remove the sulfur from the fluid streams. Sorbents comprising zinc oxide are especially useful in the removal of sulfur from fluid streams. However, these sulfur oxide sorbents tend to gradually lose their impregnation capacity or sulfur loading, and thus REF: 25391 become less useful. These degraded sorbents are often called deactivated sorbents. Until now, the technique has not completely taken up the question of what to do with these deactivators. Consequently, a process to reactivate these deactivated sorbents is very needed and desired. BRIEF DESCRIPTION OF THE INVENTION It is a process of this invention to provide a process for reactivating a deactivated sorbent to produce a reactivated sorbent. In accordance with this invention, a process for reactivating a deactivated sorbent is provided to produce a reactivated sorbent. This process comprises (or optionally: consists essentially of, or consists of): (a) contacting a deactivated sorbent with a zinc composition comprising zinc oxide, or a zinc oxide precursor, to form a composition that is has contacted; (b) drying the composition that has been contacted at a temperature in the range of about 25 ° to about 375 ° C, for a period of time in the range of about 1 minute to about 24 hours, for forming a composition that has been put in dry contact; and (c) calcining the composition that has been brought into dry contact at a temperature in the range of about 400 ° C to about 800 ° C, for a period of time ranging from about 1 minute to about 24 hours. hours, to form the reactivated sorbent. Other objects of this invention will be apparent to those skilled in the art from the following detailed description of the invention, and the claims. DETAILED DESCRIPTION OF THE INVENTION Sorbents can be used to remove hydrogen sulfide from a fluid stream. Hydrogen sulfide can be produced by the hydrodesulfurization of organic sulfur compounds, or it can be originally present in the fluid stream as hydrogen sulfide. Examples of such fluid streams include: light hydrocarbons such as methane, ethane and natural gas; gases derived from petroleum products and products of extraction, gasification, and / or liquefaction of coal and 1; gases derived from sand mixed with tar and ski oil; synthesis gas (mixture of a part of carbon oxide and 2 parts of hydrogen) derived from petroleum; gases such as hydrogen and nitrogen; gaseous carbon oxides; vapor and inert gases such as helium and argon. Additional information regarding the types of processes can be found in U.S. Patent No. 5,281,445 (the full disclosure of which is incorporated herein by reference). The process for reactivating a deactivated sorbent to form a reactivated sorbent comprises, in general, contacting a deactivated sorbent with a zinc composition comprising zinc oxide, or a zinc oxide precursor, to form a composition that has been contacted, drying the composition that has been brought into contact with it. a temperature in the range of about 25 ° C to about 375 ° C, for a period of time in the range of about 1 minute to about 24 hours, to form a composition that has been contacted, dried, and calcining the composition that has been contacted, dried, at a temperature in the range of about 4 ° C to about 800 ° C, for a period of time in the range of about 1 minute to about 24 hours , to form the reactivated sorbent. For the purposes of this specification, the phrase "deactivated sorcerum" means a sorbent which has been used in a process that removes sulfur from a fluid stream, and which has seen its sulfur loading capacity decreased, when compared to the sorbent not used. These deactivated sorbents comprise, when not used, zinc oxide. Processes for producing sorbents comprising zinc oxide are well known in the art, and can be found in the following US Patents: 4,990,318; 5,077,261; 5,094,996; 5,102,854 5, 108,975; 5,130,288; 5,143,706; 5,174,919; 5,177,050 5,178,843; 5,219,542; 5,244,641; 5,248,489; 5,250,089 5,268,152; 5,281,445; 5,306,685; 5,310,717; 5,358,921 5,360,468; 5,370,848; 5,439,867; the full descriptions of which are incorporated herein by reference. One of the greatest benefits of this invention is obtained when the deactivated sorbent used in this invention has seen its sulfur loading capacity decreased by more than 40 percent. The deactivated sorbent is contacted with a zinc composition comprising zinc oxide, or a zinc oxide precursor. The zinc composition used in the preparation of the reactivated sorbent can be either in the form of zinc oxide, or in the form of zinc oxide precursors which are convertible to zinc oxide under the preparation conditions described herein. Examples of such zinc oxide precursors include zinc sulfide, zinc sulfate, zinc hydroxide, zinc carbonate, zinc acetate, zinc nitrate and mixtures of any two or more thereof. Preferably, the zinc composition is in the form of a solution of the zinc oxide precursor in water, such as, for example, zinc nitrate in water. It is preferred to use a zinc oxide precursor in solution in water as the zinc composition, to contact the deactivated sorbent with the zinc composition, and thereby impregnate the deactivated sorbent with the zinc composition. The amount of zinc present in the composition that has been contacted is in the range from about 10 weight percent to about 90 weight percent, and more preferably it will be in the range from 20 weight percent to 80 weight. percent by weight, and more preferably will be in the range from 40 percent by weight to 70 percent by weight, based on the weight of the composition that has been contacted. The composition that has been contacted is then dried, at a temperature in the range from about 25 ° C to about 375 ° C, more preferably, from 50 ° C to 300 ° C, for a period of time from near from 1 minute to about 24 hours, more preferably, from 1 hour to 6 hours, to form a composition that has been contacted, dried. The composition that has been contacted, dried is then calcined at a temperature from about 400 ° C to about 800 ° C, more preferably, from 500 ° C to 700 ° C, for a period of time from about 1 minute to about 24 hours, more preferably, from 1 hour to 6 hours, to form a composition that has been put in dry, calcined contact, which is the reactivated sorbent. The calcination step can be carried out in air and / or nitrogen. However, it is preferred to carry out the calcination step in an oxygen-containing atmosphere. The reactivated sorbent may additionally comprise metal promoters selected from groups 6 through 11 of the periodic table (see Hawlwey's Condensated Chemical Dictionary, llava edition, inner front cover of the IUPAC nomenclature). Examples of these metal promoters are chromium, molybdenum, tungsten, manganese, technetium, rhenium, iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, and gold. Currently, a preferred metal promoter is nickel. Mixtures of these metal promoters can also be used. The metal promoter can be added to the reactivated sorbent in the form of an elemental metal and / or a metal-containing compound, which is convertible to a metal oxide under the calcining conditions described herein. Some examples of such metal-containing compounds include metal acetates, metal carbonates, metal nitrates, metal sulfates, metal thiocyanates, and mixtures of any two or more thereof. The elemental metal and / or the metal-containing compound can be contacted with the reactivated sorbent by any method known in the art. One such method is the impregnation of such sorbent with a solution, either aqueous or organic, containing the elemental metal and / or the metal-containing compound. After the elemental metal and / or the metal-containing compound has been contacted with such a sorbent, the promoted sorbent is dried and calcined, as described herein. It should be noted that the elemental metal and / or the metal-containing compound can also be mixed with the deactivated sorbent and the zinc composition to form the composition that has come into contact, thereby simplifying the production process. The metal promoter will usually be present in the reactivated sorbent in an amount ranging from about 0.1 weight percent to about 30 weight percent, and more preferably it will be in the range from 2.0 weight percent about 15 percent by weight, based on the weight of the reactivated sorbent.

The following example is presented to further illustrate the invention. EXAMPLE This example illustrates the reactivation of a deactivated sorbent according to this invention. Freshly prepared sorbent was used in a hot gas purification unit, until the sorbent was deactivated. This sorbent was designated Sorbent A. Sorbent A was regenerated by contacting it with a stream of gas, which contained oxygen, to remove a portion of the sulfur therefrom. This contact took place in a temperature range from 535 ° C to 760 ° C. This sorbent was designated Sorbent A-1. Fifteen grams of Sorbent A-l was contacted with 13.7 grams of Zn (N03)? .6H20 dissolved in 10 ml of warm deionized water (about 50 ° C), to form a composition that has been contacted. This composition which has been brought into contact was then heated in an oven at about 50 ° C for one hour, and then cooled to room temperature. The resulting contacted composition was then dried at about 150 ° C for one hour, and then calcined, in air, at about 635 ° C for one hour. This composition that has been put in dry and calcined contact was designated Sorbent B.

To test the effectiveness of the Al and B Sorbents, they were subjected to a standard sorption test, in which each sorbent was contacted alternately with gaseous streams containing either: (1) hydrogen sulfide (H2S) mixed with inert gases, such as carbon dioxide (C02) and nitrogen (N2); or (2) steam or air, or both. Stage (1) is the loading stage, where the sorbent is loaded with sulfur. Step (2) is the regeneration step, wherein the sorbent is removed at least a portion of the charged sulfur. The temperature of the reactor for stage (1) was from about 425 ° C to about 540 ° C, and for stage (2) it was from about 590 ° C to about 760 ° C. It was determined that the load of sulfur on the sorbent was complete when hydrogen sulfide was detected in 100 ppm in the effluent stream, at this point the sorbent contaminated with sulfur was regenerated in air. The test data for Sorbents A-1 and B are in Table One and Table Two. 1 This is in terms of the percent by weight of the sulfur, based on the total weight of the sorbent.

These results clearly show that Sorbent B, which was produced according to this invention, increases the sulfur loading capacity when compared to Sorbent A-l by about 70 to 80%. Additionally, they show that Sorbent B has a sulfur loading capacity suitable for commercial operations.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following:

Claims

CLAIMS 1. A process for reactivating a deactivated sorbent, to produce a reactivated sorbent, the process is characterized in that it comprises: (a) contacting a deactivated sorbent with a zinc composition comprising zinc oxide, or an oxide precursor zinc, to form a composition that has been contacted; (b) drying the composition that has been contacted at a temperature in the range of about 25 ° C to about 375 ° C, for a period of time ranging from about 1 minute to about 24 hours, to form a composition that has been put in dry contact; and (c) calcining the composition that has been put in dry contact, at a temperature in the range of about 400 ° C to about 800 ° C, for a period of time in the range of about 1 minute to about 24 hours, to form the reactivated sorbent.
2. A process according to claim 1, characterized in that the zinc composition comprises a zinc oxide precursor, selected from the group consisting of zinc sulphide, zinc sulfate, zinc hydroxide, zinc carbonate, zinc acetate , zinc nitrate and mixtures of any of two or more thereof.
3. A process according to claim 2, characterized in that the zinc composition is in the form of a solution of the zinc oxide precursor in water.
4. A process according to claim 3, characterized in that the deactivated sorbent is impregnated with the solution of the zinc oxide precursor in water.
5. A process according to claim 1, characterized in that the amount of zinc present in the composition that has been contacted is in the range from about 16 weight percent to about 90 weight percent, based on the weight of the composition that has been put in contact.
6. A process according to claim 1, characterized in that the composition that has been put in contact is dried at a temperature from 50 ° C to 300 ° C for a period of time from about 1 minute to about 24 hours.
7. A process according to claim 1, characterized in that the composition that has been put in contact, dry, is calcined at a temperature from 500 ° C to 700 ° C, for a period of time from about 1 minute to about 24 hours
8. A process according to claim 1, characterized in that the reactivated sorbent further comprises a metal promoter, wherein the metal in the metal promoter is selected from the group consisting of chromium, molybdenum, tungsten, manganese, technetium, rhenium, iron. , ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, gold, and mixtures thereof.
9. A process according to claim 1, characterized in that the reactivated sorbent further comprises a metal promoter, wherein the metal in the metal promoter is nickel.
10. A process for reactivating a deactivated sorbent, to produce a reactivated sorbent, the process is characterized in that it consists essentially of: (a) contacting a deactivated sorbent with a zinc composition consisting essentially of a selected zinc oxide precursor of the group consisting of zinc sulphide, zinc sulfate, zinc hydroxide, zinc carbonate, zinc acetate, zinc nitrate and mixtures of any two or more thereof, to form a composition that has come into contact; (b) drying the composition which has been contacted at a temperature in the range of 50 ° to 300 ° C, for a period of time in the range of about 1 minute to about 24 hours, to form a composition which has been put in dry contact; Y (c) calcining the composition that has been contacted, dried, at a temperature in the range of 500 ° C to 700 ° C, for a period of time in the range of about 1 minute to about 24 hours, for form the reactivated sorbent. PROCESS FOR REACTIVATING DISABLED SORBENTS SUMMARY OF THE INVENTION The present invention describes a process for reactivating a deactivated sorbent, to produce a reactivated sorbent. This process comprises: (a) contacting a deactivated sorbent with a zinc composition comprising zinc oxide, or a zinc oxide precursor, to form a composition that has been contacted; (b) drying the composition that has been contacted at a temperature in the range of about 25 ° to about 375 ° C, for a period of time in the range of about 1 minute to about 24 hours, for forming a composition that has been put in dry contact; and (c) calcining the composition that has been brought into dry contact at a temperature in the range of about 400 ° C to about 800 ° C, for a period of time ranging from about 1 minute to about 24 hours. hours, to form the reactivated sorbent.