US3101303A - Process for regenerating manganese oxide acceptors for hydrogen sulfide - Google Patents

Description

Au fzo, 1963 x m EXPRESSION .Oi'ginal Filed Feb. 13, 1958 2 Sheets-Sheet 1 HIGH SULFUR NET CARBONACEOUS FLUE GAS GAS soLms AND so T u 20 REGENERATED 4X 2 ACCEPTOR DESULFURIZATIO'NY REGENERATION l7 la l6 SULFIDED '9 g I ACCEPTOR LOW SULFUR AIR CARBONACEOUS souos 40 50 so 10 e0 90 I00 OF MnS REGENERATED v INVENTORS- .1. D. BATCHELOR ETEAL PROCESS FOR REGENERATING MANGANESE OXIDE ACCEPTORS FOR HYDROGEN SULFIDE JAMES D. BATCHELOR GEORGE P. CURRAN EVERETT GORIN TORNEY D. BATCHELOR a-rAL PROCESS FOR REGENERATING MAN 3 0 1 0 3 E D I X 0 E S m. m

Aug. 20, 1963 ACCEPTORS FOR HYDROGEN SULFIDE Original Filed Feb. 13, 1958 2 Sheets-Sheetv 2 TIME MINUTES XMnO 0 Mn O TIME MINUTES .0. -7-v w a O n ./M 02 1% mm s N n v M W ,4E .M T 2 O O O O O O O O O 0 8 6 4 2 8 6 4 2 INVENTORS R v O LN M N RI 7 CRR v| 0 7 E B v R w Tv O 7 3 s ERR A M0 na Y B United States Patent 3,101,303 PROCESS FOR REGENERATENG MANGANESE OXIDE ACCEPTQRS FUR HYDROGEN SUlLlFiDE James D. Batchelor, Springfield, Va., and George P. Curran and Everett Gorin, Pittsburgh, Pa, assiguors to Consolidation Coal Company, Pittsburgh, Pa, a corporation of Pennsylvania Continuation of application Ser. No. 715,136, Feb. 13, 1958. This application Apr. 29, 1960, Ser. No. 26,927 7 Claims. (Cl. 2023l) The present invention relates to a process for regenerating manganese oxide acceptors for hydrogen sulfide. More particularly, it relates to a process for removing sulfur contamination from carbonaceous solid materials by treatment with hydrogen in the presence of manganese oxide-type solid acceptors for hydrogen sulfide.

Such sulfur removal processes for carbonaceous solid fuels have been described in copending U.S. patent application S.N. 527,705, now US. Patent 2,824,047, filed August 11, 1955, by Everett Gorin', George P. Curran and James D. Batchelor, assigned to the assignee of the present invention. A further process relating to sulfur removal and calcining of carbonaceous solid fuel briquets has been described in copending US. patent application S.N. 635,278, since abandoned, filed January 22, 1957, by James D. Batchelor, Everett Gorin, George P. Curran and Robert J. Friedrich, assigned to the assignee of the present invention.

The presence of sulfur in carbonaceous solid fuels limits their use in metallurgicalapplications. Accordingly, most metallurgical fuels are obtained by employing low sulfur content starting materials, e.g., low sulfur coal is converted to low sulfur metallurgical coke. Sulfur removal processes of the typedescribed in the aforemen tioned patent applications permit the use of high sulfur content fuels as starting materials for preparing low sulfur content carbonaceous fuels for metallurgical use. For example, the sulfur removal process may be provided as a treatment for the solid residue (termed char) resulting from low temperature carbonization of bituminous coal. Where fluidized low temperature carbonization processes are used, the finely divided, low density, porous char productis particularly amenable to those desulfurization treatments. The desulfurization treatment can be applied to any non-caking carbonaceous solid fuel such as cokes and chars. Coke from coal and hydrocarbonaceous residues (pitch coke), coke breeze, and low temperature carbonization' char from coal and lignite are exemplary. The processes cannot be applied to caking carbonaceous solid fuels such as caking coal since the thermal treatment encompassed in such processes would cause these materials to become sticky and form coked masses which would bind the acceptor solids, thus preventing their recovery for reuse in the process. Further the resulting coke would be contaminated with the acceptor solids. Any sulfur transferred from the carbonaceous fuels to the bound acceptor solids would remain in the solid coke. The processes, however, are applicable to the desulfurization of carbonaceous briquets which may contain caking coal inter alia provided the thermal treat ment is conducted to avoid severe caking and accompanyiug formation of large coke masses.

In the aforementioned copending application S.N. 527,705 solid carbonized carbonaceous fuels are desulfurized by treatment at elevated temperatures in the presence of hydrogen and a solid acceptor for hydrogen sulfide. A preferred acceptor in this process is one containing manganese oxide. Examples of manganese oxide acceptors include particles of substantially pure manganese oxide, inert supports such as silica, alumina and silicaalumina impregnated with manganese oxide, and high three forms.

, 3,101,303 .Patented Aug.- 20, 1963:

"ice

manganese content naturally occurring ores having a low content of silica-alumina, calcium and iron. The natu rally occurring ores are more fully describedin our copending application SerialNo. 715,058, now-US. Patent 2,950,231, filed February 13, 1958, by James D. Batchelor, "George P. Curran and Everett Gorin entitled Manganese Ore Acceptors for Hydrogen Sulfide. A preferred inert support is mullite which comprises about to percent alumina and the balance silica.

According to the process of US. Patent 2,824,047, carbonaceous solid fuels containing sulfur are mixed with a solid material (termed an acceptor) which is capable of absorbing hydrogen sulfide. The mixture is treated with hydrogen gas at a temperature above about 1100 F. whereby the hydrogen gas combines with the contaminating sulfur to form hydrogen sulfide; the hydrogen sulfide is absorbed in situ by the acceptor. Since the hydrogen sulfide is absorbed instantly upon formation, there is only a negligible paitial pressure of hydrogen sulfide in the desnlfurization zone for inhibiting the reactions whereby sulfur is removed from the carbonaceous solid fuels. The reaction mixture of solids is separated into (a) product desulfurized carbonaceous solid fuels and (b) the solid acceptor containing accepted sulfur. The acceptor may be regenerated and heated by contact with [air to restore its hydrogen sulfide acceptor properties through elimination of previously absorbed sulfur. The heated regenerated acceptor, when mixed with relatively cool carbonaceous solid fuels preferably provides the heat necessary to raise the solids reaction mixture to a desulfurization temperature.

Where the sulfur-containing carbonaceous solid fuel is in the form of finely divided particles (e.g., fluidized low temperature carbonization char, petroleum coke and the like), the acceptor preferably is larger in size to facilitate separation'of desulfurized fuel from the sulfided acceptor. When the sulfur-containing carbonaceous solid fuel is in the form of relatively large agglomerate masses, such as briquets, the acceptor preferably is in the form of finely divided fluidizable size particles to improve contacting efficiency and to facilitate separation of desulfurized fuel from the sulfided acceptor.

carbonaceous solid fuels contain sulfur in at least Some of the sulfur exists as readily removable sulfur Which is organically bound in the carbonaceous fuel. This, organically bound sulfur can be removed from the carbonaceous solid fuels rather easily by contact with hydrogen. If the readily removable, organically bound sulfur is represented as C=S, the desulfurization reaction may be represented as follows:

carbonaceous solid fuel with pure hydro-gen gas. The

reaction (assuming iron sulfide) is as follows:

FeS+H H S+Fe The equilibrium ratio for-this reaction His/H is very low. Hence small quanties of hydrogen. sulfide in the gas phase will inhibit the transfer of sulfur from the solid to the gas. At 1350 F., for exa rnple,0.l2 volume percent of hydrogen sulfide in the hydrogen gas is the equilibrium value. At 1600 F., 0.28 volume percent of hydrogen sulfide in the hydrogen gas is the equilibrium value. Thus in order to remove inorganically, bound sulfur effectively, the ratio of H S/H must be maintained at an extremely low value,-i.e., nearly pure hydrogen must be used. 7

A further type of sulfur existing in the solid carbonaceous fuels'is identified as difiicultly removable sul- 3 fur which is principally organically bound. This type of sulfur exists in the form of refractory organic material and various inorganic sulfides. While this sulfur theoretically can the removed by treatment of the carbonaceous solid fuels with pure hydrogen gas, nevertheless, even minutetraces of hydrogen sulfide are sulficient to inhibit the transter of sulfur from the solids to the gas. Removal of the difiicultly removable sulfur is not practicable under feasible processing conditions.

The ultimate desulfurization which can be achieved at any temperature depends upon the ratio of H s/H in the treating gases without regard to the absolute pressure of the reaction system. While greater absolute pressure increases the rate of desulfurization, it does not aifect the ultimate level of sulfur in the treated solids. In accordance with these findings, satisfactory desulfurization rates may be achieved at temperatures above about 1100 F. with atmospheric pressure. Higher pressure accomplishes the same desulfur'ization in shorter time. A preferred pressure range for the desulfurization is about 1 to 6 atmospheres absolute.

It is possible to maintain a low value for the ratio H s/H by employing enormous quantities of hydrogen as a treating gas. For example, the use of 1000 molar volumes of pure hydrogn gas in removing one mol of sulfur would create an environment containing 0.10 volume percent of H 8 in H Alternatively, the ratio H s/H may be maintained at a low value by removing the H 8 from the vapor state as quickly as it is formed. The removal of H from the vapor state can be accomplished by providing in a desulfurization zone a solid acceptor which has a greater afiinity for hydrogen sulfide than those materials with which the sulfur is bound in the carbonaceous solid fuels. A preferred solid acceptor is one containing manganese oxide.

Throughout the specification, the term manganese oxide refers to compounds containing manganese and oxygen, such as MnO, Mn O Mn O MnO which compounds are principally in the form of MnO. The term higher oxides of manganese refers to compounds containing more than one atom of oxygen per atom of mantganese, e.g., Mn O Mn O MnO The reaction of the manganese oxide in the desulfurization treatment is as follows:

Thus the manganese oxide combines with the generated hydrogen sulfide to form manganese sulfide thereby removing from the vapor phase the hydrogen sulfide formed by desulfurization of the carbonaceous solid fuel.

Following sufiicient desulfurizing treatment of the carbonaceous sol-id fuels, the desulfurized fuels are separated from the solid acceptor and recovered as a low sulfur carbonaceous fuel product. As such, the low sulfur carbonaceous solid fuels are suitable for use as metallurgical fuels.

The separated sulfided acceptor is regenerated by treatment with air to restore the manganese oxide for reuse as follows:

Thus in the overall process, the sulfur removed from the carbonaceous solid fuels is rejected from the system in the form of sulfur dioxide. So much of the process has been more fully described in the aforementioned application, S.N. 527,705.

The use of H 5 acceptors has been'briefly described in relation to desulfunization processes for carbonaceous solid fuels. Such H 8 acceptors also can be used for removing H 5 from any gas stream, regardless of source. For example, elimination of 1-1 8 from petroleum refinery gases, pipeline gas, and the like can be accomplished by passing the gases over an H S-accepto-r containing manganese oxide. The H 8 will be absorbed by the acceptor and the manganese oxide converted to manganese sulfide.

w The sulfided acceptor can be regenerated by treatment with air to release sulfur dioxide and restore the manganese oxide.

The phrase H sabsorbing conditions as employed in this specification refers to a non-oxidizing environment containing H S at temperatures Where a favorable equilibrium exists for the reaction The preferred temperature range for H s-absorbing conditions is about 1100 to 16 00" F. The ability of an acceptor to react with H 8 under H S-ahsorbing conditions is an important determinant in the efficiency of the fundamental desulfurization process.

Undesirable over-oxidation may accompany the regeneration whereby higher oxides of manganese are produced, for example, Mn O and Mn O The presence of these higher oxides of manganese is deleterious for tWo reasons.

First, the higher oxides of manganese are reduced immediately upon return to the desulfurization zone by reacting with hydrogen gas therein.

M11304 Mn O -l-H 2MnO+H O Consumption of valuable hydrogen in this manner is inefiicient since there is no accompanying desulfurization.

Second, the reduction of these higher oxides of manganese produce water vapor which tends to suppress the H 3 absorption reaction.

The reaction equilibrium for the H 8 absorption is a function of pH O/ H S. Extraneous water vapor in the system will limit the rate of H 5 absorption.

The object of the present invention is to minimize the production o-fhigher oxides of manganese in the acceptor regeneration treatment.

According to the present invention, a portion of the MnS in the acceptor is allowed to remain in the acceptor throughout the regeneration treatment. By allowing about 2 to 15 percent of the manganese to remain in the form of MnS, the yield of MnO is unexpectedly selective to the substantial exclusion of the undesirable higher oxides of manganese. The residual MnS does not affect the subsequent H S absorption properties of the acceptor since the MnS passes through the desulfurization zone unchanged.

In the preferred embodiment, the acceptor is used not only to remove H S from the vapor in the desulufurization zone but also to provide the heat requirements for raising the temperature of the carbonaceous solids (undergoing desulfurization) to the desired desulfurization temperature. Thus there exists an overwhelming stioohiometric excess of MnO in the desulfurization zone, dictated by the heat balance requirements.

For a full understanding of the present invention, its objects and advantages, reference should be had to the following detailed description and accompanying drawings in which:

IGURE 1 is a schematic flow diagram illustrating a desulfurization process for carbonaceous solid fuels employing solid acceptors \for hydrogen sulfide;

FIGURE 2 is a graphical illustration of the state of oxidation of the manganese oxide acceptor according to the extent of sulfur removal in the regeneration zone; and

FIGURE 3 is a graphical illustration of the manner in which the regenerating oxygen is distributed among three competing reactions in the regeneration zone.

The generalized flow sheet of FIGURE 1 illustrates the manner in which an acceptor desulfiurization process can he carried cutin a continuous manner. A desulfurization zone It) receives non-caking carbonaceous solids containing sulfur through a conduit 11 and regenerated acceptor solids through a conduit 12. In this instance, the

hydrogen gas, are autogenously produced through devolatilization of the carbonaceous solids at the elevated temperature of the desulfurization zone 10. Under preferred operating conditions the autogenously produced devolatilization gases will be in sufiicient quantity to provide the full hydrogen requirements for desulfurization so that extrinsic hydrogen production is not required.

The desulfurization zone 10 is maintained at a temperature from about 1100 to about 1600 F. Belowv about 1100 F., the desulfurization rate is low. Operation above about 1600 F. requires excessive heat and also promotes rapid deactivation of the acceptor. The pressure level preferably is high enough to provide a 'hydrogen gas partial pressure of at least one atmosphere. A total pressure of from one to six atmospheres is preferred.

A t pical char (containing sulfur) produced by fluidized carbonization of Pittsburgh Seam coal at 950 yields devolatilization gases containing 58.6 percent hydrogen and 24.8 percent methane at 1.3 atmospheres and 1350 F. The same char yields devolatilization gases 5 containing 48.7 percent hydrogen and 32.9 percent methane at 3 atmospheres and 1350 F.

During passage through the des-ulfurization zone 10,

the treating gases remove sulfur from the carbonaceous solid fuels.

forming hydrogen sulfide.

The H S, upon formation, is at once absorbed by the solid acceptor and removed from the gas phase.

furization desired. It must be borne in mind that theultimate sulfur level of the product is determined by the level of H 5 concentration which the managnese oxide will maintain. Where the hydrogen partial pressure of the treating gases is about one atmosphere or greater,

satisfactory desulfurization can be achieved by subjecting 5 the carbonaceous solids to the desulfurization conditions for a period of about three hours or less. Increased absolute pressure, as already pointed out, promotes more rapid desulfurization.

Desulfurized carbonaceous solids are removed from the desulfurization zone 10 as product through a conduit 16.. Sulfided acceptor is removed through a conduit 17 and passed to an acceptor regeneration zone 18. Air is introduced into the regeneration zone 18 through a conduit 19 to raise the temperature of the acceptor through combustion of su fur along with a portion of the carbonaceous solids commingled therewith and to remove sulfur; therefirom through oxidation to sulfur dioxide.

MnS+%O MnO+SO +heat The temperature within the regeneration zone 18 is maintained at about 1300 to 1800 F. Hot flue gases containing sulfur dioxide are removed from the regenerationzone"v 13 through a conduit 20.

Excessive oxidation in the regeneration zone 18 will result in the conversion of some MnO to higher oxides of. manganese as described. According to the present invention, the residence time and oxygen input rate are regulated to restrict the oxidation such that from about 2,

to about 15 percent of the available manganese remains 6 in the vform of MnS. The two-mentioned variables are regulated such that the amount of oxygen introduced is within about 20 percent of that stoichiometrically determined for complete oxidation of all the MnS entering the regeneration zone 18. Substantially complete COHSUITIP-e tion of the introduced oxygen will occur. This oxygen in part is consumed by the desired reaction MnS-1 7 0 MnO-l-SO -l-heat and in part through combustion of carbonaceous, solids to provide the heat requirements for the process and also in part to produce the undesirable higher oxides of manganese I 3MI1O+1/2O2+MI13O4.

ZMnO /2 0 Mn O Regenerated acceptor is returned to the desulfurizatiou zone 10 through the conduit 12 without deliberate cooling 0 v to serve therein as a means for removing H 8 therefrom and to supply the heat requirements thereof.

To illustrate the unexpected results accruing from the practiceo-f the present invention, an introductory explanation of the terminology will be helpful. In considering a mixture of various oxides of manganese (MnO, Mn O M11 0 for example) the ratio of oxygen to manganese can be calculated and the mixture can be identified by the empirical formula: MnO Where x is the calculated ratio.

If all the manganese exists as MnO, the value of x is 1.00. If all the manganese exists as Mn O the value of x is 1.33. If all the manganese exists as M11 0 the value of x is 1.50. By this system of representation, it is apparent that the desired value of x in the empirical expression for the oxides of manganese should approximate 1.00 for a regenerated acceptor entering the desulfurization zone.

Referring to FIGURE 2, the value of x in the expression MnO has been graphically presented as a function of the percentage of MnS which is oxidized during regeneration in air. To develop the curve of FIGURE 2, a sulfided acceptor was exposed to oxygen in a fluidized 'bed at 1700 F. The specific acceptor was a substantially pure screened fraction of manganese oxide. The

material was prepared by decomposing manganese nitrate to manganese oxide. .The manganese oxide was briquetted, calcined, crushed and screened. Samples of the acceptor were drawn periodically for analysis. About 60 percent of the available manganese was in the (form of MnS when regeneration was commenced. The associated carbon was finely divided particles of pitch coke.

From FIGURE 2, it is seen that the yield of higher oxides of manganese is negligible until the last portion of the MnS begins to oxidize, as evidenced by the value of x in the expression MnO 'The value of x does not rise above 1.01 until about 90 percent of the MnS has been oxidized. Thereafter the value of x increases markedly as the residual. M113 is oxidized. Hence it appears that formation of significant quantities of higher oxides of O manganese can be avoided by allowing a portion of the MnS to remain on the acceptor during the regeneration treatment.

For a further illustration of the present inventionpthe curves of FIGURE 3 present graphically the distribution of oxygen entering a batch-wise acceptor regeneration zone as a function of time. A specific acceptor was the same substantially pure material described in connection with FIGURE 2. Initially the sulfided acceptor contained about 60 percent of its manganese as MnS. Some finely divided pitch coke particles were comrningled with.

the sulfided acceptor. Air was passed through the acceptor-coke mixture as a fluidizing gas.

About percent of the initial oxygen reacts with the MnS to form MnO. exclusively; the remainder of the initial oxygen reacts with carbon from the coke to supply heat; none of the initial oxygen reacts with MnO to form higher oxides of manganese. Following about five minutes treatment at a constant air input rate, only a minor portion of entering air reacts with MnS. The bulk of the air is used in the carbon combustion reaction. A significant portion of the air is consumed in forming undesirable higher oxides of manganese from the MnO already produced. Regeneration treatment extending beyond about five minutes (at the air input rate used to develop the curves of FIGURE 3) would result only in a slight decrease of the MnS content of the acceptor at the expense of a significant increase in the content of undesirable higher oxides of manganese.

The cross hatched area under the curves of FIGURE 3 corresponds to the cumulative amount of oxygen consumed in each of the three competing reactions. Continuing the regeneration treatment beyond about five minutes would produce more higher oxides of manganese than MnO (from NnS) under the conditions employed for obtaining the data to develop the curves of FIGURE 3.

The exact cut-off point for the regeneration will vary according to the relative oxygen-to-sulfided acceptor flow rate. However, a satisfactory cut-off will be achieved when from about 2 to about 15 percent of the MnS on the sulfidedacceptor is allowed to remain on the regenerated acceptor. The utilization of oxygen in the regeneration process will be nearly quantitative, i.e., substantially all of the oxygen introduced will be consumed. Accordingly, the quantity of oxygen should be within about twenty percent of that determined stoichiometrically for reacting with all of the available MnS.

The temperature range for the regeneration is from about 1300 to 1800 F, preferably from about 1300 to 1600 F. Where the acceptor comprises an inert support such as silica-alumina, silica or alumnia impregnated with manganese oxide, regeneration should be conducted at a relatively low temperature within the range. Elevated temperature treatment of supported acceptor promotes deactivation of the manganese as described in our copending applications S.N. 692,865, now U.S. Patent 2,927,063, filed October 28, 1957; SN. 692,897, now US. Patent 2,950,229, filed October 28, 1957; and S.N. 695,467, now US. Patent 2,950,230, filed November 8, 1957. Regeneration of high manganese content acceptors preferably is conducted at somewhat higher temperatures within the range 1300 to 1800 F. High manganese content acceptors include those prepared from substantially pure manganse oxide as well as those comprising naturally occurring manganese ores as set forth in copending application SrN. 715,058, now US. Patent 2,950,231, filed by us February 13, 1958.

The present process can be applied to advantage in an cyclic desulfurization process employing manganese oxide acceptors and also employing hydrogen gas as the sulfur transferring medium. Gaseous streams and vaporized sulfur-containing liquids can be desulfurized as well as the carbonaceous solid fuels herein described.

According to the provisions of the patent statutes, we have explained the principle, preferred construction, and mode of operation of our invention and have illustrated and described what we now consider to represent its best embodiment. However, we desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

This application is a continuation of our application Serial No. 715,136, now abandoned, filed February 13, 1958.

We claim:

1. in a process employing solid acceptors containing manganese oxide for absorbing hydrogen sulfide at temperatures above about 1100 F. to form manganese sulfide, followed by oxidizing the manganese sulfide to manganese oxide by reaction with oxygen, wherein undesired higher oxides of manganese are formed, in said lastmentioned step the improvement which minimizes formation of said higher oxides, comprising controllably oxidizing only about to 98 percent of the sulfide sulfur in said sulfided acceptors so as to maintain about 2 to 15 percent of the manganese in the form of MnS, whereby a major portion of the manganese is in the form of MnO and formation of higher oxides of manganese is minimized, and recovering the thus-treated regenerated acceptors for reuse under H s-absorbing conditions.

2. The improvement of claim 1 wherein the solid acceptor comprises a manganese-oxide impregnated inert support which is an oxide selected from the class consis ing of silica, alumina and silica-alumina and the regeneration temperature is between 1300 and l600 3. The improvement of claim 2 wherein the inert support comprises mullite.

4. The improvement of claim 1 wherein the solid acceptor comprises substantially pure manganese oxidev 5. The improvement of claim 1 wherein the solid acceptor comprises particles of naturally occurring high manganese content ore.

6. In a process employing solid acceptors containing manganese oxide for absorbing hydrogen sulfide at temperatures above about 1100 F. to form manganese sulfide, followed by oxidizing the manganese sulfide to manganese oxide by reaction with oxygen, wherein undesired higher oxides of manganese are formed, in said lastmentioned step the improvement which minimizes formation of said higher oxides, comprising introducing into a regeneration zone maintained at a temperature from 1300 to 1800 F. relative quantities of sulfided acceptors, combustible carbon, and oxygen so that only about 85 to 98 percent of the sulfided sulfur in said sulfided acceptor is oxidized, withdrawing acceptor from said regeneration zone containing 2 to 15 percent of its sulfide sulfur and containing a major portion of its manganese in the form of MnO, and recovering the withdrawn acceptors as a stream for reuse under H S-absorbing conditions.

7. In the method for removing sulfur from particulate carbonized carbonaceous solids which comprises preparing an intimate admixture of said carbonaceous solids and particulate acceptor solids comprising manganese oxide, subjecting said admixture to treatment at a temperature above 1100 F. in the presence of hydrogen gas until a portion of the initial sulfur has been removed from said carbonaceous solids and transferred to said acceptor solids thereby forming manganese sulfide, separating particulate acceptor solids containing manganese sulfide from low sulfur carbonaceous solids as product, and restoring the H 8 absorbing property of sulfided acceptor solids for recirculation in the process, the improvement in said last-mentioned step comprising introducing into a regeneration zone maintained at a temperature from 1300 to 1800 F. relative quantities of sulfided acceptor, combustible carbon, and oxygen so that only about 85 to 98 percent of the sulfide sulfur in said sulfided acceptor is oxidized, withdrawing acceptor from said regeneration zone containing 2 to 15 percent of its sulfide sulfur and containing the major portion of its manganese in the form of MnO, and recovering the withdrawn acceptor as a stream for reuse under H s-absorbing conditions.

References Cited in the file of this patent UNITED STATES PATENTS 2,086,507 Carson July 6, 1937 2,764,528 Sweeney Sept. 25, 1956 2,824,047 Gorin et a1. Feb. 18, 1958 2,950,230 Batchelor et al Aug. 23, 1960 FOREIGN PATENTS 708,554 Great Britain May 5, 1954 519,283 Canada Dec. 6, 1,955

Claims (1)

1. IN A PROCESS EMPLOYING SOLID ACCEPTORS CONTAINING MANGANESE OXIDE FOR ABSORBING HYDROGEN SULFIDE AT TEMPERATURES ABOVE ABOUT 1100*F. TO FORM MANGANESE SULFIDE, FOLLOWED BY OXIDIZING THE MANGANESE SULFIDE TO MANGANESE OXIDE BY REACTION WITH OXYGEN, WHEREIN UNDESIRED HIGHER OXIDES BY REACTION WITH OXYGEN, WHEREIN UNDESIRED MENTIONED STEP THE IMPROVEMENT WHICH MINIMIZES FORMATION OF SAID HIGHER OXIDES, COMPRISING CONTROLLABLY OXIDIZING ONLY ABOUT 85 TO 98 PERCENT OF THE SULFIDE SULFUR IN SAID SULFIDE ACCEPTORS SO AS TO MAINTAIN ABOUT 2 TO 15 PERCENT OF THE MANGANESE IN THE FORM OF MNS, WHEREBY A MAJOR PORTION OF THE MANGANESE IS IN THE FORM OF MNO AND FORMATION OF HIGHER OXIDES OF MANGANESE IN MINIMIZED, AND RECOVERING THE THUS-TREATED REGENERATED ACCEPTORS FOR REUSE UNDER H2S-ABSORBING CONDITIONS.

Images