KR20070056129A - A desulfurization system and method for desulfurizing a fuel stream - Google Patents

Abstract

Supplying a non-sulfur fuel cell hydrocarbon fuel stream and passing the fuel stream through a series of sulfur adsorption bed systems containing at least one selective sulfur adsorbent and a calcium ion exchange zeolite to produce substantially desulfurized hydrocarbon fuel streams. A method for producing a substantially desulfurized hydrocarbon fuel stream comprising the step at a temperature of less than 100 ° C.

Desulfurization, fuels, selective sulfur adsorbents, calcium ion exchange zeolites, fuel cells

Description

Desulfurization System and Desulfurization Method of Fuels {A DESULFURIZATION SYSTEM AND METHOD FOR DESULFURIZING A FUEL STREAM}

The present invention allows the passage of non-sulfur hydrocarbon fuel streams, in particular natural gas, propane or liquefied petroleum gas (LPG), through a series of sulfur adsorption bed systems at temperatures below 100 ° C. And, more particularly, to a novel process for producing substantially desulfurized hydrocarbon fuel streams for use in fuel cell processing trains, wherein the series of sulfur adsorption bed systems comprises a zeolite sulfur adsorbent and at least one Contains a selective sulfur adsorbent. The invention further relates to a system for generating electricity in a fuel cell processing train from substantially desulfurized hydrocarbon fuels, in particular desulfurized natural gas, propane or LPG, wherein the hydrocarbon fuels are a series of sulfur adsorbents described above. Desulfurization is carried out using a bed system. The present invention further includes a desulfurization system used for hydrogen evolution in a fuel cell processing train for desulfurizing hydrocarbon fuels, in particular natural gas, propane or LPG at temperatures as low as room temperature.

In particular, for the generation of hydrogen for use in conventional low temperature fuel cell processing trains, such as proton exchange membrane (PEM) fuel cells, suitable for use in stationary applications or in vehicles such as automobiles. Flows can be derived from a number of conventional fuel sources, preferred fuel sources of which include natural gas, propane and LPG. In conventional hydrogen generation systems, in particular fuel cell processing trains, hydrocarbon fuel streams are desulfurized by passing over and / or through the desulfurization system. This desulfurized hydrocarbon fuel for such a fuel cell processing train is then introduced to a reformer, where the fuel is converted to a hydrogen-rich fuel stream. From the reformer, the fuel stream passes through one or more heat exchangers and proceeds to a shift converter where the CO content in the fuel stream is reduced. From this shift converter the fuel flows again through various heat exchangers and then through an optional oxidizer or optional methanizer with one or more catalyst beds, after which the hydrogen rich fuel stream It enters the cell stack and is used to generate electricity.

Raw or gaseous raw fuels, in particular natural gas, propane and LPG, are particularly useful as fuel sources for hydrogen generation for fuel cell processing trains. Unfortunately, virtually all raw fuels contain a variety of naturally occurring sulfur compounds up to a relatively high level, ie as high as 1000 pm, but typically contain in the range of 20 to 500 ppm, which is a variety of naturally occurring sulfur. Compounds include carbonyl sulfide, hydrogen sulfide, thiophenes such as tetrahydro thiophene, dimethyl sulfide, various mercaptans, disulfides, sulfoxides, other organic sulfides, high molecular weight organic sulfur compounds and combinations thereof However, it is not limited thereto. In addition, hydrocarbon fuels, in particular natural gas, propane and LPG may have different sources, so the weight and composition of sulfur compounds that may be present in the fuel stream may vary considerably.

The presence of these sulfur-containing compounds in hydrocarbon fuel streams can be very detrimental to the components of the fuel cell processing train, including the fuel cell stack itself, and must therefore be sufficiently removed. If not removed sufficiently, sulfur compounds will shorten the life of components of the fuel cell processing train.

Since fuel cell processing trains generally include a single desulfurization system, a particularly efficient desulfurization system is required for use in such fuel cell processing trains. In addition, desulfurization systems for such applications must be high performance, as they may need to be used for an extended time before their replacement.

Several methods, conventionally called "desulfurization", have been used to remove sulfur from gas and liquid fuel streams for hydrogen evolution. Adsorption of sulfur-polluted compounds in these hydrocarbon streams using "physical" sulfur adsorbents is the most common method of removing sulfur compounds from such hydrocarbon fuels because of their relatively low capital and operating costs. Method (in this specification, the terms “adsorption” and “absorption” are the same, inclusive meaning). While physical adsorbents are useful, they can be susceptible to the release of sulfur compounds from adsorbents under certain working conditions. In addition, there is often a limit to the amount of sulfur compounds that can be adsorbed by such physical sulfur adsorbents.

An additional form of adsorbent useful as a desulfurizer is a "chemical" sulfur adsorbent. However, chemical desulfurization usually requires a desulfurization bed where the non-sulfurization hydrocarbon fuel stream is heated to a temperature of about 150 ° C. to 400 ° C. before passing through the chemisorption desulfurization system. In addition, other practical problems may arise when chemical desulfurization methods are used.

Although many different desulfurization methods have been proposed for carbon fuels, there is still a need for an improved desulfurization process to achieve promoted adsorption of sulfur with an extended range of sulfur concentrations, especially for extended periods of time at relatively low temperatures and pressures. have. Moreover, significant amounts of a wide range of sulfur compounds such as hydrogen sulfide, carbonyl sulfide, tetrahydro thiophene, dimethyl sulfide, various mercaptans, disulfides, sulfoxides, other organic sulfides, various high molecular weight sulfur-containing compounds and their There is still a need for desulfurization systems that adsorb combinations. In addition, it is important for the desulfurization system to effectively adsorb such a wide range of sulfur compounds for an extended period of time to delay the "breakthrough" of the sulfur compounds as much as possible. "Breakthrough" occurs when the concentration of any sulfur compound remaining in the feed stream after desulfurization is above a predetermined concentration. Typical "breakthrough" concentrations for sulfur compounds occur at around 1 ppm. In addition, breakthrough by any one of the actual sulfur compounds present in the hydrocarbon fuel stream is disadvantageous, such that all sulfur compounds harm components of the hydrogen generation system, particularly for fuel cell processing trains.

In addition, some adsorbents of the prior art are effective as adsorbents for some sulfur compounds, but are capable of synthesizing the product of additional sulfur compounds even by removing some of the sulfur compounds present in hydrocarbon fuel streams. Sulfur compound ("synthesized sulfur compound"). It is important that the desulfurization system avoid the production of these synthetic sulfur compounds as broadly as possible and for the longest possible time.

These and further aspects of the invention will be apparent from the description of the preferred embodiments of the invention described below.

Summary of the Invention

The present invention is a method of supplying a substantially desulfurized hydrocarbon fuel for hydrogen generation, in particular for use in a fuel cell processing train, the method comprising the steps of providing a non-sulfurized hydrocarbon fuel, a calcium exchanged zeolite sulfur adsorbent And preparing a desulfurization system comprising a series of sulfur adsorption bed systems containing at least one optional sulfur adsorbent, and passing non-desulfurized hydrocarbon fuel streams through or above the desulfurization system, optimally at a temperature below 100 ° C. Passing through to produce a substantially desulfurized hydrocarbon fuel stream with a desulfurization level as low as about 50 ppb. The composition and selection of the selective sulfur adsorbent (s) and the order of use of the selective absorbent (s) and calcium ion exchange zeolites in the desulfurization system depend on the composition of the sulfur compounds present in the fuel stream.

The present invention also provides a system for generating electricity in a fuel cell processing train using substantially desulfurized hydrocarbon fuel streams, the method comprising the steps of preparing a fuel cell processing train comprising the desulfurization system described above, a non-sulfur hydrocarbon fuel cell fuel stream Is passed through a desulfurization system, preferably below 100 ° C., and a step of injecting substantially desulfurized hydrocarbon fuel streams into the remaining components of the fuel cell processing train.

The present invention also relates to a desulfurization system, in particular for the generation of hydrogen for use in fuel cell processing trains, which comprises intake ports for receiving non-sulfurized hydrocarbon fuels, in particular natural gas, propane or LPG, a series of adsorbent bed systems described above, and And an outlet for passing the substantially desulfurized hydrocarbon fuel stream downstreams towards the remaining components of the hydrogen generation system.

The invention is also a series of sulfur adsorption bed systems for the generation of hydrogen, particularly for use in fuel cell processing trains containing selective sulfur adsorbent (s) and calcium ion exchange zeolites. The order of use of certain selective sulfur adsorbents or adsorbents and the selective sulfur adsorbents or adsorbents and zeolites within the series of sulfur adsorbent beds depends on the composition and amount of sulfur compounds present in the hydrocarbon fuel stream. One or more optional sulfur adsorbents may be used with calcium ion exchange zeolites to form the series of adsorbent bed systems of the present invention. One particularly preferred selective sulfur adsorbent contains at least one manganese compound, iron oxide and a carrier of a large surface area, in particular alumina. Alternative preferred selective sulfur adsorbents contain one or more manganese compounds, copper oxide and binder material.

1 is a graph showing the performance of calcium ion exchange zeolites discussed in Example 1 for the removal of certain sulfur compounds in a synthetic natural gas feed stream.

FIG. 2 is a graph showing the performance of the selective sulfur adsorbent of Example 2 for removal of the sulfur compound of Example 1 in the synthetic natural gas feed stream of Example 1. FIG.

3 is a performance of a mixture of the zeolite of Example 1 and the optional sulfur adsorbent of Example 2 to remove the sulfur compounds of Example 1 from the synthetic natural gas feed of Example 1, as discussed in Example 3; A graph representing.

Publication of Preferred Embodiments of the Invention

The present invention includes a method of supplying a substantially desulfurized hydrocarbon fuel stream to a hydrogen generation system, in particular a fuel cell processing train. Such hydrogen generating systems, in particular raw fuels for use in fuel cell processing trains, such as natural gas, propane and LPG, must be desulfurized because of the presence of naturally occurring relatively high concentrations of sulfur compounds before they are used. Examples include hydrogen sulfide, carbonyl sulfide, thiophenes such as tetrahydro thiophene, dimethyl sulfide, mercaptans (including ethyl, methyl propyl and tertiary butyl mercaptans), other sulfides, various high molecular weight organic sulfur compounds and their Combinations include, but are not limited to. Such sulfur compounds can damage components of the hydrogen generation system and fuel cell processing trains. Although many combinations and large amounts of such sulfur compounds may be present in the fuel stream, in some situations, the sulfur compounds present in the fuel stream may be limited to only one or two sulfur compounds. When the raw fuel contains natural gas present in the gaseous state at a working temperature of 100 ° C. or lower, sulfur compounds such as carbonyl sulfide, hydrogen sulfide, tetrahydro thiophene, dimethyl sulfide, mercaptan and other organic sulfur compounds , And combinations thereof may be as high as about 100 ppm. The presence of such high concentrations of sulfur compounds, if not removed, can result in poisoning of the fuel cell processing train components and can contaminate the fuel cell stack itself. It is necessary to complete the removal of substantially all of the sulfur compounds because even the presence of only a few sulfur compounds can damage the components of the fuel cell processing train.

The desulfurization system of the present invention can be used in a number of different hydrogen generation methods, but one particularly preferred use is for fuel cell processing trains. Although one preferred use is within the scope of a fuel cell processing train, all hydrogen generating systems are included for the purposes of this specification.

Surprisingly, the inventors have found that when using a series of sulfur adsorption bed systems as desulfurization systems containing zeolite adsorbents, in particular one or more optional sulfur adsorbents used in combination with calcium ion exchange zeolites, more specifically calcium ion exchange X zeolites. In turn, it has been found that significant desulfurization can be achieved which lowers the sulfur content of hydrocarbon fuels for fuel cell processing trains to concentrations on the order of 50 ppb. The composition and order of use of the components of the series of sulfur adsorbent bed systems can be adjusted according to the composition and amount of sulfur compounds present in the hydrocarbon feed stream.

The optional sulfur adsorbent (s) of the present invention are selected from a variety of adsorbents. As used herein, “selective sulfur adsorbent” means sulfur compounds such as hydrogen sulfide, which are typically present in hydrocarbon fuel cell fuels, specifically natural gas, propane, LPG, at temperatures up to 100 ° C. and pressures of about 10-250 psig; Refers to a substance that predominantly adsorbs at least one of carbonyl sulfide, tetrahydro thiophene, dimethyl sulfide, mercaptan, specifically ethyl, methyl, propyl, and tertiary butyl mercaptan and combinations thereof.

Each selective sulfur adsorbent selectively adsorbs one or more sulfur compounds commonly present in fuel cell fuel streams, preferably natural gas. However, each of these adsorbents may be less or more effective than other sulfur adsorbents that are selective for adsorption of certain sulfur compounds or combinations of these compounds. In addition, additional problems may arise when several selective sulfur adsorbents are used alone as sulfur adsorbents, since such selective sulfur adsorbents do not remove the sulfur compounds present from the fuel stream by certain selective sulfur adsorbents. It is because it can synthesize | combine with the synthetic sulfur compound of different high molecular weight.

Surprisingly, it has been found that the performance of the desulfurization system can be significantly enhanced by using zeolite adsorbents, specifically calcium ion exchange zeolites, and more specifically calcium ion exchange X zeolites with selective sulfur adsorbents. In addition, the adsorption of a wide range of sulfur compounds from hydrocarbon fuel cell fuel streams can occur when one or more optional sulfur adsorbents are used with zeolite adsorbents in a series of sulfur adsorbent bed systems. Specifically, the combination of one or more selective sulfur adsorbents and calcium ion exchange zeolite adsorbents performed better than when each selective sulfur adsorbent or calcium ion exchange zeolite was used individually. Moreover, the selection and arrangement of selective sulfur adsorbent (s) and zeolites in a series of sulfur adsorbent bed systems can reduce the tendency of synthetic sulfur compounds often produced when only a single selective sulfur adsorbent is used in the desulfurization system.

In addition, it has been found that removal of various combinations of sulfur compounds can be enhanced by the specific arrangement of adsorbents in a series of sulfur adsorbent bed systems. For example, for the removal of one type or group of sulfur compounds, it is desirable to place calcium ion exchange zeolites in front of the selective sulfur adsorbent in a series of sulfur adsorbent beds, while non-sulfurization for other sulfur compounds or combinations of sulfur compounds. Preferably, the hydrocarbon fuel cell fuel stream is in contact with one of the optional sulfur adsorbents before contacting the calcium ion exchange zeolite. For other non-sulfur hydrocarbon fuel cell fuel streams, it may be desirable to use two or more selective sulfur adsorbents, one or more of which are disposed before or after the zeolite adsorbent in a series of sulfur adsorbent bed systems.

Some sulfur compounds, which may be synthesized into larger and more difficult to remove sulfur by certain selective sulfur adsorbents, may be synthesized in the feed stream by zeolite adsorbents, specifically calcium ion exchange zeolite adsorbents, before they are synthesized by such sulfur adsorbents. Since it can be eliminated, the sulfur adsorption by this system is further enhanced.

Suitable selective sulfur adsorbents are substantially manganese-based adsorbents such as adsorbents containing manganese compounds, adsorbents containing manganese compounds, copper oxides and binders, and adsorbents containing manganese compounds, iron oxides and carriers with a large surface area, in particular alumina. Groups are selected from, but are not limited to, groups of adsorbents. Other useful optional sulfur adsorbents for such desulfurization systems include zinc oxide with or without carriers such as alumina; Copper oxide containing activated carbon; A combination of zinc oxide / copper oxide, preferably containing a small amount of carbon and alumina; Alumina bearing copper oxide; And copper oxide / zinc oxide blends mixed with alumina. Other useful optional sulfur adsorbents may include nickel and other known selective sulfur adsorbents containing copper, zinc, molybdenum and cobalt compounds on silica or alumina. These selective sulfur adsorbents can be used in various amounts, respectively, and the amount of individual components can be adjusted according to the specific sulfur compounds and their amounts present in the hydrocarbon fuel cell fuel stream to enhance the adsorption capacity of the overall desulfurization system.

In one particularly preferred embodiment, the selective sulfur adsorbent has a large surface area carrier, preferably a large surface area carrier comprising alumina, silica, silica-alumina, titania, and other inorganic refractory oxides, of which more preferred carriers have a large surface area. Alumina), and at least one manganese compound mixed with iron oxide. The term "wide surface area" refers to a carrier having a surface area of greater than 100 m ² / g.

Surprisingly, the inventors have found that when a large surface area carrier is a large surface area alumina, the ability of the manganese compound (s) / iron oxide selective sulfur adsorbent to adsorb sulfur compounds is enhanced. Adsorbents containing manganese compound (s) / iron oxide materials having a large surface area of alumina can adsorb sulfur compounds at a higher level than when the carrier contains other inorganic materials with similar surface areas. Any form of alumina having a surface area of at least 100 m ² / g is within the scope of the present invention. Preferred carriers comprise from 5 to 25%, preferably from 5 to 20%, and most preferably from 5 to 15% by weight of the total weight of this selective sulfur adsorbent. The main function of the carrier material is to provide a wide and accessible surface area for the deposition of the active metal compound.

In addition to one or more manganese compound (s), metal oxides deposited on or with carriers of a large surface area of such selective sulfur adsorbents include iron oxide. In a preferred embodiment, the iron oxide and manganese compound (s) together constitute at least 60% by weight, preferably at least 70% by weight and most preferably at least 80% to 90% by weight of this sulfur adsorbent.

In a preferred embodiment, the amount of iron oxide present in this selective sulfur adsorbent exceeds the amount of manganese compound (s). It is preferred that the weight ratio of iron oxide to manganese compound (s) should be at least 1: 1 and preferably 1: 1 to 6: 1. Preferred iron oxide loadings on the carrier range from 40% to 80% by weight, and more preferably from 50 to 70% by weight relative to the total weight of the optional sulfur adsorbent. Various forms of iron oxides can be used, such as FeO and Fe ₂ O ₃ and mixtures thereof.

The at least one manganese compound (s) constitutes 15% to 40% by weight, preferably 20% to 40% by weight of the total weight of the selective sulfur adsorbent. Various forms of manganese compounds can be used, including MnO ₂ , Mn ₂ O ₃ , Mn ₃ O ₄ and Mn (OH) ₄ and mixtures thereof.

Accelerators or accelerators may also be added to these selective sulfur sorbents, preferably from 5 to 15% by weight of alkali metal oxides or alkaline earth metal oxides and more preferably calcium oxide. Calcium oxide is the preferred promoter, but other alkali metal oxides or alkaline earth metal oxides, such as magnesium oxide, may be used in addition to or instead of calcium oxide.

Selective sulfur adsorbents of iron oxide / manganese compound (s) according to the present invention may be prepared by coprecipitation, decomposition, impregnation or mechanical mixing. Preferably, such selective sulfur sorbents are produced by coprecipitation or decomposition. The method chosen should ensure thorough mixing of the optional sulfur sorbent components.

The specific pore volume of the iron oxide / manganese compound (s) adsorbent produced by the procedure, measured by mercury porosimetry, is preferably between 0.3 cc / g and 0.6 cc / g. In addition, the compacted bulk density of such selective sulfur sorbents is preferably between 0.4 and 1.1 g / cc. Once the material is present in its main product form, it is further processed by pelletization or extrusion to form the final selective sulfur adsorbent. Such selective sulfur adsorbents are preferably molded in molding, in particular in the form of spheres or pellets, preferably having a diameter in the range of from 0.1 cm to 1 cm in size. The surface area of such selective sulfur adsorbents is at least 100 m ² / g and preferably 100 m ² / g to 300 m ² / g.

The volume ratio of such alumina bearing iron oxide / manganese compound (s) selective sulfur adsorbent to calcium ion exchange zeolite adsorbent is from 1: 4 to 4: 1, preferably from 1: 3 to 3: 1. In a sequence of using such selective sulfur adsorbents with a calcium ion exchange zeolite adsorbent in a series of selective sulfur adsorbent bed systems, the calcium ion exchange zeolite adsorbent is preferably placed before this selective sulfur adsorbent.

These iron oxide / manganese compound (s) selective sulfur adsorbents exhibited particularly good sulfur adsorption when used alone, wherein the sulfur compounds contained in the fuel cell fuel stream are hydrogen sulfide, carbonyl sulfide (COS), tertiary Butyl mercaptan (TBM) and ethyl mercaptan (EM). When such selective sulfur adsorbents are used with calcium ion exchange zeolite adsorbents, they are enhanced for the adsorption of additional sulfur compounds commonly present in fuel cell fuel streams, including tetrahydrothiophene (THT) and dimethyl sulfide (DMS). The utility was shown, particularly when specific zeolites were placed in front of the iron oxide / manganese compound (s) adsorbent in sequence in a series of sulfur adsorbent bed systems. However, some hydrocarbon fuels do not contain such additional sulfur compounds. In such circumstances, it is an alternative preferred embodiment to use only an iron oxide / manganese compound (s) selective sulfur adsorbent without a calcium ion exchange zeolite adsorbent.

Other selective sulfur adsorbents may be used with these selective sulfur adsorbents and zeolite adsorbents for the adsorption of certain sulfur compounds in hydrogen generating systems such as hydrocarbon fuel cell feed streams. For example, a particularly useful combination is a combination of calcium ion exchange zeolite and iron oxide / manganese compound (s) selective sulfur adsorbents having a large surface area carrier and selective containing copper oxide containing carbon or alumina with copper oxide / zinc oxide. Contains sulfur adsorbent. Such selective sulfur adsorbents are described in more detail herein below. In the order of using these additional selective sulfur adsorbents with zeolite adsorbents, carbon / copper oxide or copper oxide / zinc oxide selective sulfur adsorbents are first placed in a series of sulfur adsorbent bed systems, and iron oxide / with alumina having a large surface area It is preferred to place the zeolite adsorbent in front of the manganese compound (s).

In one preferred embodiment of this combination, the zeolite adsorbent is preferably equal to or greater than the amount of other components in the three component system in the series of sulfur adsorbent beds, wherein the amount of zeolite adsorbent is the total amount present in the series of sulfur adsorption bed systems. Up to 80% of sulfur adsorbent, alumina bearing iron oxide / manganese compound (s) The selective sulfur adsorbent constitutes up to 20% by volume of a series of sulfur adsorbent bed systems and is selective sulfur of alumina bearing carbon / copper oxide or copper oxide / zinc oxide The adsorbent may also constitute up to 20% by volume of the series of sulfur adsorbent bed systems.

Additional preferred optional sulfur adsorbents that may be used with zeolite adsorbents in a series of sulfur adsorbent bed systems may contain one or more manganese compound (s), copper oxide and small amounts of binder. The manganese compound (s) of such selective sulfur adsorbents may be used in any of the forms already described for the manganese compounds of the selective sulfur adsorbents described above. The manganese compound (s) of this selective sulfur adsorbent constitutes 50-80% by weight and preferably 60-75% by weight of this selective sulfur adsorbent. Copper oxide constitutes 15-40% by weight and preferably 15-30% by weight of this selective sulfur adsorbent. The binder constitutes 5-20% by weight of this selective sulfur adsorbent. In a preferred embodiment, the binder is selected from a wide range of clays including bentonite, diatomaceous earth, attapulgite, kaolin, sepiolite, illite and mixtures thereof do. More preferably, the binder contains bentonite clay. Accelerators may also be added to the selective sulfur adsorbents to enhance the working properties of the adsorbents. Such adsorbents are prepared by conventional procedures. The surface area of the manganese compound (s) / copper oxide selective sulfur adsorbent with binder is from 100 to 300 m ² / g, preferably from 200 to 300 m ² / g.

Selective sulfur adsorbents of these manganese compound (s) / copper oxide / binder, when used alone, show significant utility for hydrogen sulfide, carbonyl sulfide, tertiary butyl mercaptan, ethyl mercaptan and mixtures thereof. In addition, the sulfur contained in a hydrocarbon fuel cell feed of the same type as described above when such manganese compound (s) / copper oxide / binder selective sulfur adsorbents are used in sequence with zeolite adsorbents in a series of sulfur adsorbent bed systems. Significant adsorption of the compound was shown wherein the composition of the selective sulfur adsorbent contained iron oxide, manganese compound (s) and a small amount of large surface area alumina.

The volume ratio of the selective sulfur adsorbent and zeolite adsorbent for removing sulfur compounds from fuel cell fuels, specifically natural gas, propane and LPG, is 1: 4 to 4: 1 and preferably 1: 3 to 3: 1.

Other optional sulfur adsorbents of the same morphology, same amount, and in the same order, which can be used with small amounts of large surface area alumina bearing iron oxide / manganese compound (s), are also used with these selective sulfur adsorbents and zeolite adsorbents to form a three component system. In addition, the adsorption of specific sulfur compounds present in the fuel cell fuel stream can be enhanced. The selection of the particular selective sulfur adsorbent or adsorbents used may be adjusted depending on the specific sulfur compound present in the feed stream and the amount thereof.

Instead of, or in addition to, the optional sulfur adsorbents described above, additional optional sulfur adsorbents that may be used with zeolite adsorbents in a series of sulfur adsorbent bed systems contain only zinc oxide, or contain zinc oxide with the carrier. Alumina is the preferred carrier, but other carriers having similar performance characteristics may also be used. In a preferred embodiment, the zinc oxide constitutes at least 60% by weight, preferably 50 to 95% by weight, and more preferably 70 to 90% by weight of the selective sulfur adsorbent and the remainder is preferably composed of alumina. . Additives may be added to these selective sulfur sorbents to enhance the ability to absorb sulfur compounds or other performance characteristics. The surface area of such selective sulfur adsorbents is 5 to 75 m ² / g and preferably 10 to 50 m ² / g. These zinc oxide / alumina selective sulfur sorbents are prepared by conventional procedures.

When the zinc oxide alumina selective sulfur adsorbent was used alone as the sulfur adsorbent, good sulfur adsorption was exhibited when the sulfur compounds contained in the fuel cell fuel stream were hydrogen sulfide and ethyl mercaptan and mixtures thereof.

The inventors have found that the adsorption of sulfur compounds is enhanced when such alumina bearing zinc oxide selective sulfur adsorbents are used in a series of sulfur adsorbent bed systems with the zeolite adsorbents of the present invention. Preferably, in the order of adsorbents in a series of sulfur adsorbent bed systems, the alumina bearing zinc oxide selective sulfur adsorbent is used after the zeolite. In a preferred embodiment, the volume ratio of alumina bearing zinc oxide selective sulfur adsorbent to zeolite adsorbent is from 1: 4 to 4: 1 and in more preferred embodiments from 1: 3 to 3: 1. Although the selected series of sulfur adsorbent bed systems contain only zeolite adsorbents with alumina-bearing zinc oxide selective sulfur adsorbents, depending on the sulfur content and composition in the fuel cell fuel stream, additional optional sulfur adsorbents may also be employed in the series of sulfur adsorbent bed systems. As part, it may be used before or after the zeolite adsorbent and such optional sulfur adsorbent.

Another optional sulfur adsorbent that can be used with the zeolite adsorbent of the present invention in a series of sulfur adsorbent bed systems contains activated carbon containing a small amount of copper oxide. In a preferred embodiment, this activated carbon constitutes 80 to 95% by weight, preferably 85 to 95% by weight of this selective sulfur adsorbent, with the remainder being copper oxide. Additives may be added to the composition to enhance its performance. Activated carbon / copper oxide selective sulfur sorbents are prepared by conventional procedures. The surface area of this composition is 300 to 1000 m ² / g, preferably 500 m ² / g to 1000 m ² / g. Such selective sulfur adsorbents are prepared by conventional procedures.

When such activated carbon / copper oxide selective sulfur adsorbent is used alone, it has shown considerable utility in adsorbing tetrahydro thiophene, tertiary butyl mercaptan, ethyl mercaptan and mixtures thereof.

The volume ratio of activated carbon / copper oxide selective sulfur adsorbent and zeolite adsorbent used is from 1: 4 to 4: 1, preferably from 1: 3 to about 3: 1. Further, the preferred order of use of the selective sulfur adsorbent and zeolite adsorbent is to place the zeolite adsorbent before the activated carbon / copper oxide selective sulfur adsorbent in a series of sulfur adsorbent bed systems.

These activated carbon / copper oxide selective sulfur adsorbents, when used in conjunction with other selective sulfur adsorbents and zeolite adsorbents, also showed good adsorption capacity for the adsorption of a wide range of sulfur compounds contained in fuel cell feed streams.

Another useful optional sulfur adsorbent that can be used with a zeolite adsorbent in a series of sulfur adsorbent bed systems contains copper oxide and alumina bearing zinc oxide, preferably with a small amount of carbon. In a preferred embodiment, the copper oxide constitutes 50 to 65% by weight of the selective sulfur adsorbent, more preferably 50 to 60% by weight. Zinc oxide constitutes 20-35% by weight of the selective sulfur adsorbent, and alumina constitutes 5-20% by weight, preferably 10-20% by weight of the selective sulfur adsorbent. If used, the amount of carbon should be less than 10% by weight, preferably 1 to 10% by weight. The surface area of such selective sulfur adsorbents containing copper oxide, zinc oxide, alumina and preferably small amounts of carbon is from 100 to 300 m ² / g and preferably from 100 to 200 m ² / g. The method for producing such selective sulfur adsorbent is in accordance with the conventional production method.

Adsorption of hydrogen sulfide, tertiary butyl mercaptan, ethyl mercaptan, carbonyl sulfide and mixtures thereof when such a copper oxide / zinc oxide / alumina, preferably a selective sulfur adsorbent containing a small amount of carbon, is used alone Was especially useful.

When used in a series of sulfur adsorbent bed systems, the volume ratio of such selective sulfur adsorbent to zeolite adsorbent is from 1: 4 to 4: 1, preferably from 1: 3 to 3: 1. If the sulfur compound to be removed from the fuel cell fuel stream contains a sulfur compound which is particularly useful for such a selective sulfur adsorbent, the zeolite precedes the selective sulfur adsorbent in the sequence of use of such sulfur adsorbent and zeolite adsorbent in a series of sulfur adsorbent bed systems. The adsorbent is required to be disposed. In addition to copper oxide / zinc oxide / alumina and preferably sulfur bearing adsorbents, other optional sulfur adsorbents may also be used before or after such selective sulfur adsorbents in the series of sulfur adsorbent bed systems of the present invention.

Additional optional sulfur adsorbents that can be used with zeolite adsorbents in a series of sulfur adsorbent bed systems contain manganese compound (s) used alone, which are MO ₂ , Mn ₂ O ₃ , Mn ₃ O ₄ And Mn (OH) ₄ or mixtures thereof. The surface area of the manganese compound (s) is 100 to 300 m ² / g, and preferably 200 to 300 m ² / g. Additional substances such as calcium, silver and magnesium can be mixed with the manganese compound (s) to enhance the performance of the manganese compound (s). Conventional methods can be used to form such selective sulfur adsorbents.

When this manganese compound (s) selective sulfur adsorbent is used alone, it has shown considerable utility for adsorption of hydrogen sulfide, tertiary butyl mercaptan, ethyl mercaptan and mixtures thereof.

When used with zeolite adsorbents in a series of sulfur adsorbent bed systems, the volume ratio of manganese compound (s) to zeolite adsorbents used is from 1: 4 to 4: 1 and preferably from 1: 3 to 3: 1. In the order of use of such manganese compound (s) selective sulfur adsorbents in a series of sulfur adsorbent bed systems, it is preferred that the zeolite sulfur adsorbent is placed before the manganese compound (s) selective sulfur adsorbents. In addition to the use of manganese compound (s) and zeolite adsorbents, other optional sulfur adsorbents described herein may be used before or after the manganese compound (s) selective sulfur adsorbents in the series of sulfur adsorbent bed systems of the present invention.

Additional optional sulfur adsorbents that may be used with zeolite adsorbents in a series of sulfur adsorbent bed systems may contain alumina bearing copper oxide, where the content of copper oxide is from 5 to 25% by weight, preferably from 10 to 20% by weight. The content of alumina is 75 to 95% by weight, preferably 80 to 90% by weight. The surface area of such selective sulfur adsorbents is 100 to 300 m ² / g, and preferably 150 to 300 m ² / g. Such selective sulfur adsorbents are prepared by conventional procedures.

When such selective sulfur adsorbents are used alone, they have shown utility in particular for the adsorption of hydrogen sulfide, carbonyl sulfide, tertiary butyl mercaptan, ethyl mercaptan and mixtures thereof. In addition, when these copper oxide / alumina selective sulfur adsorbents are used in sequence with zeolite adsorbents in a series of sulfur adsorbent bed systems, significant adsorption to the sulfur compounds contained in the same type of fuel cell feed as described above appear. When used with a zeolite adsorbent for adsorption of sulfur compounds in a series of sulfur adsorbent bed systems, the volume ratio of selective sulfur adsorbent to zeolite adsorbent is from 1: 4 to 4: 1, preferably from 1: 3 to 3: 1. . In the order of using such a selective sulfur adsorbent and a zeolite adsorbent in a series of sulfur adsorbent bed systems, the zeolite adsorbent is preferably placed before the selective sulfur adsorbent. Other selective sulfur sorbents may also be used with such selective sulfur sorbents for the adsorption of sulfur compounds in the series of sulfur sorbent bed systems of the present invention.

Additional optional sulfur adsorbents that can be used with zeolite adsorbents in a series of adsorbent bed systems contain copper oxide, zinc oxide, and alumina, with copper oxide content of 15 to 25 weight percent and zinc oxide content of 5 to 15 % By weight, and the content of alumina is 65 to 85% by weight. The surface area of such selective sulfur adsorbents is from 100 to 300 m ² / g, and preferably from 200 to 300 m ² / g. Such selective sulfur adsorbent catalysts are prepared by conventional procedures.

When such selective sulfur adsorbents are used alone, they are particularly useful for the adsorption of hydrogen sulfide, carbonyl sulfide, tertiary butyl mercaptan, ethyl mercaptan and mixtures thereof.

When used with a zeolite adsorbent, the volume ratio of this selective sulfur adsorbent to the zeolite adsorbent is from 1: 4 to 4: 1 and preferably from 1: 3 to 3: 1. In this order of selective sulfur adsorbent and zeolite adsorbent, it is preferred that the zeolite adsorbent is placed before the selective sulfur adsorbent. Such selective sulfur adsorbents may be used with the zeolite adsorbent as well as other selective adsorbents, with the choices discussed above being preferred. For example, in one particularly preferred embodiment, such selective sulfur adsorbents may be used with zeolite adsorbents and may be used with iron oxides, manganese compounds and alumina selective sulfur adsorbents as described above.

Surprisingly, the inventors have found that the selective sulfur adsorbents described above work optimally when used in a series of sulfur adsorbent bed systems containing at least one selective sulfur adsorbent and zeolite adsorbent. Although some forms of ion exchange zeolites can be used as zeolite adsorbents, preferred ion exchange zeolites are calcium ion exchange zeolites. Although many calcium ion exchange zeolites are known, including calcium ion exchange zeolites A, zeolite X, zeolite Y, zeolite ZSM-5, zeolite beta, synthetic mordenite and mixtures thereof, preferred calcium ion exchange zeolites are calcium ion exchange Zeolite X. Particularly preferred calcium ion exchange zeolite X is calcium ion exchange, low silica zeolite X known as "LSX", and calcium exchange low silica faujasite known as "LSF". The Si: Al equivalent ratio of zeolite X is generally from 1.0 to 1.25. As an example, LSF synthesized with conventional non-calcium ion exchange precursors has a composition of 2.0 SiO ₂ : Al ₂ O ₃ : 0.73 Na ₂ O: 0.27K ₂ O, but sometimes the ratio between sodium and potassium ions Significant changes may be made depending on the method of preparation of LSF.

For the present invention, a substantial proportion of cations of zeolite X are ion exchanged with calcium ions using conventional ion exchange procedures, such as the treatment of zeolite X with calcium salts such as, but not limited to, calcium chloride. Several methods can be used in the ion exchange procedure, which preferably occurs after the zeolite adsorbent is molded into its preferred final form, such as in the form of beads or extrudates. Zeolite X is ion exchanged to at least 50%, preferably at least 60%, more preferably at least 70%, and most preferably 85 to 95% levels of the exchangeable metal ions. The remaining ions may be sodium and / or potassium ions. (Reference, "calcium ion exchange zeolite X" means zeolite X containing at least 50% calcium cation.)

The calcium ion exchange zeolite X of the present invention generally contains sodium or potassium ions in addition to calcium ions even after the exchange of calcium ions. However, some or substantially all of these sodium / potassium ions may be ion exchanged with other cations to enhance or modify the performance characteristics of calcium ion exchange zeolite X, in particular with respect to sulfur adsorption. For example, additional cations that can be ion exchanged onto zeolite X to neutralize its performance include zinc, cadmium, cobalt, nickel, copper, iron, manganese, silver, gold, scandium, lithium, and combinations thereof. The ion exchange rate of these additional metal ions may range from as low as 1% to as high as 40%, depending on the degree of calcium ion exchange of zeolite X. The particular metal ion ion-exchanged on the calcium ion exchange zeolite depends on the particular sulfur compound intended to be removed from the fuel cell fuel stream by the series of sulfur absorber bed systems of the present invention.

When calcium ion exchanged zeolites are used as the sulfur adsorbent, they are used for the adsorption of various sulfur materials, in particular tetrahydro thiophene (THT), dimethyl sulfide (DMS), tertiary butyl mercaptan (TBM) and ethyl mercaptan (EM). Significant performance was shown.

In addition, surprisingly, the performance when the selective sulfur adsorbents described above are used individually and the performance when the calcium ion exchange zeolites are used separately are mixed with calcium ion exchange zeolite X and the selective sulfur adsorbent to desulfurize the hydrocarbon fuel cell feed stream. It has been found that it can be dramatically enhanced by forming a series of sulfur adsorbent beds. The mixed use of such selective sulfur adsorbents and calcium ion exchange zeolites enables the adsorption of a wider range of sulfur-containing compounds than the sulfur-containing compounds conventionally adsorbed using each component alone. For example, carbonyl sulfide, hydrogen sulfide, tetrahydro thiophene, dimethyl sulfide, and various mercaptans such as ethyl, methyl, propyl by use in combination with the above-mentioned selective sulfur adsorbents and the calcium ion exchange zeolite X described above It has been found that enhanced adsorption of a wide range of sulfur compounds, including tertiary butyl mercaptan and combinations thereof, is possible.

Surprisingly, the breakthrough times for all sulfur compounds typically present in hydrocarbon fuel systems are also accurately ordered by using at least one selective sulfur adsorbent and calcium ion exchange zeolite X and in a series of sulfur adsorbent bed systems. It has also been found that by extending it.

Surprisingly, it has been found that by placing calcium ion exchange zeolite X in front of one or more selective sulfur adsorbents in a series of sulfur adsorbent bed systems, the tendency to produce synthetic sulfur compounds is significantly reduced.

Surprisingly, the inventors have also found that the series of sulfur adsorbent bed systems of the present invention can be used at temperatures lower than those normally used for conventional sulfur adsorption. Conventional chemical sulfur adsorbents require a feedstream temperature of at least 150 ° C. to 400 ° C., but the series of sulfur adsorption bed systems of the present invention can be effectively used to adsorb sulfur contaminants at temperatures below 100 ° C. It is effective for the removal of some sulfur compounds even at low temperatures. Moreover, because of the low service temperature, a series of sulfur adsorption beds are easier to use than when high temperatures are needed.

In addition, when a series of sulfur adsorption beds of the present invention are used, the pressure on the feed stream is from 1 bar to 18 bar, preferably lower than that normally used for adsorption of sulfur compounds in conventional fuel cell processing trains. It may be reduced to a range as low as 1.7 bar to 7 bar range.

The inventors also found a method of supplying substantially desulfurized hydrocarbon fuels to a fuel cell processor using the series of sulfur adsorption bed systems described above. In this method, the sulfur-contaminated fuel stream passes through the top of a series of adsorbent bed systems of the fuel cell processor of the present invention at about room temperature to 100 ° C, preferably below 60 ° C, more preferably at room temperature, or Pass through a series of adsorbent bed systems. By passing a hydrocarbon fuel containing sulfur components at a level of about 500 ppm or less, such as natural gas, propane or LPG, a substantial reduction in the content of such sulfur compounds, preferably to a level below about 50 ppb, is achieved. Can be.

The inventors have also found that the series of sulfur adsorbent bed systems of the invention described above can be used in desulfurizers, in particular for use in fuel cell processing trains. This desulfurizer is a series of sulfur sorbent bed systems of the present invention as described above, and desulfurization, arranged at the inlet to receive non-sulfur hydrocarbon fuels such as natural gas, propane or LPG, and at the position for desulfurization of hydrocarbon fuels. The hydrocarbon fuel stream includes an outlet that passes downstream for subsequent processing. For example, desulfurized hydrocarbon fuels pass through a fuel cell processing train to a fuel cell stack for generation of electricity.

Surprisingly, the inventors have also found that a method of supplying substantially desulfurized hydrocarbon fuels is advantageous over conventional desulfurization systems, which allows for the desulfurization of a wide range of sulfur compounds and extends the breakthrough time for the system. Different combinations of selective sulfur sorbents used in a series of sulfur sorbent bed systems, depending on the sulfur compounds present in the particular feed stream, reducing the production of synthetic sulfur compounds, reducing the temperature and pressure required for the feed stream. And the content can be selected. The compositions and methods of the present invention also enable the production of hydrocarbon fuels substantially desulfurized to sulfur levels below the sulfur level in conventional desulfurization processes.

The inventors have also found that the series of sulfur adsorbent bed systems of the present invention can be used in fuel cell processors while still achieving a high level of sulfur adsorption for longer periods of time than conventional adsorbents.

The inventors have also found that the series of sulfur adsorbent bed systems of the present invention is not easy to escape adsorbed sulfur compounds, which often occurs with conventional sulfur adsorbents when the environment around the catalyst bed changes.

The following examples are intended for purposes of illustration of the invention and are intended to teach those skilled in the art how to make and use the invention. These examples are not intended to limit the invention in any way.

To illustrate the practice of the present invention, the inventors compared the performance when various sulfur adsorbents were used alone and in combination. In each example, a synthetic natural gas feed containing 93% methane, 3% ethane, 2% propane, 0.2% butane, 1% carbon dioxide and 0.75% nitrogen was used. This synthetic natural gas also contained tert-butyl mercaptan or ethyl mercaptan ("mercaptan") and tetra hydrothiophene ("THT"), respectively, 10 ppm (as sulfur). This synthetic natural gas was passed through an artificial reactor containing 10 cc of the selected sulfur adsorbent or adsorbents in the bed. When two sulfur adsorbents were used together, the amount of adsorbent was 7.5 cc of the zeolite sulfur adsorbent described in Example 1 and 2.5 cc of the selective sulfur adsorbent described in Example 2. Zeolite adsorbent was in the form of 2 mm spheres. The selective sulfur adsorbent was 1.18 mm x 0.85 mm mesh particles typically produced in 1.6 mm extrudate by grinding. The adsorbents were sized and loaded into the reactor, and the synthetic natural gas feed was passed through the reactor. The temperature of the feed stream was maintained at 38 ° C. with a space velocity of 1500 hr ⁻¹ at a pressure of 2 bar. In this test, "breakthrough" occurred when more than 50 ppb of sulfur was observed in the natural gas feed after passing through the adsorptive bed. To determine the gaseous sulfur concentration of the feed stream, the analysis was performed using an Agilent 6890 gas chromatograph equipped with an Antek 7090 sulfur analyzer. This gas chromatograph uses a 60m × 320μ DB-1 capillary column for the separation of sulfur compounds. The Antek 7090 uses a sulfur chemiluminescence analyzer (SCD) for the analysis of sulfur. The working detection limit of the system was approximately 50 ppb (mole). The test unit was controlled by automation software.

Example  One

Synthetic natural gas containing mercaptan and THT was passed through a reactor containing only calcium ion exchange zeolite X. The Si: Al equivalent ratio of this zeolite X was 1.17, the calcium ion exchange was 70%, and the remaining metal ions were ions containing sodium and / or potassium. The temperature of the reactor was maintained at 38 ° C. and the pressure at about 2 bar. The sulfur adsorption of the calcium ion exchanged zeolite is shown in FIG. 1, which shows the initial breakthrough for mercaptan at 268 hours.

Example  2

A reactor containing only 34% by weight of manganese compounds, 54% by weight of iron oxides containing Fe ₂ O ₃ , and 12% by weight of alumina having a surface area of 294 m ² / g containing synthetic natural gas containing mercaptan and THT. Passed through. The performance of this selective sulfur adsorbent is shown in FIG. 2 where the peak breakthrough occurred in less than 25 hours. The sulfur compound (s) produced here are “synthetic sulfur compounds” because the breakthrough for THT did not occur until after 100 hours. A "synthetic sulfur compound" is considered to be at least one high molecular weight sulfur compound produced in the interaction of THT and / or mercaptans with a selective sulfur adsorbent.

Example  3

Additional tests were performed using the calcium ion exchange zeolite of Example 1 in a reactor with the selective sulfur sorbent of Example 2. 75% by volume of the sulfur adsorbent was zeolite and 25% by volume was the selective sulfur adsorbent. 10 cc of mixed adsorbent was used. Zeolites in the reactor were placed before the selective sulfur adsorbent. The remaining operating conditions and the composition of the feed stream were the same as in Example 1 and Example 2. When the feed stream passed through the reactor, no breakthrough occurred until 496 hours as shown in FIG. 3.

As will be evident in these embodiments, the combination of calcium ion exchange zeolite and selective sulfur adsorbent increases the time of sulfur breakthrough, prevents the formation of synthetic sulfur compounds, and extends the life of a series of sulfur adsorbent bed systems. .

As various changes and modifications can be made to the disclosed embodiments without departing from the spirit of the invention, the invention should not be construed as limiting.

Claims (14)

Feeding a hydrocarbon feed contaminated with sulfur compounds, and The sulfur-polluted feed stream is passed through a series of sulfur sorbent bed systems containing the selective sulfur adsorbent and calcium ion exchange zeolite sulfur adsorbent, preferably calcium ion exchange zeolite X or LSX to produce a substantially desulfurized hydrocarbon feed stream. Wherein, the calcium ion exchange zeolite comprises at least 50%, preferably at least 70% and more preferably 85 to 95% of the exchangeable metal ions exchanged with calcium ions. Desulfurization method. The method of claim 1, wherein when the feed stream passes through the series of sulfur sorbent bed systems, the temperature of the series of sulfur sorbent bed systems is between room temperature and 100 ° C. The method of claim 1 or 2, wherein the selective sulfur adsorbent contains a manganese-based sulfur adsorbent. The method of claim 1, wherein the selective sulfur adsorbent is substantially ZnO; CuO and carbon; CuO, ZnO and carriers; And CuO and alumina; And a mixture thereof, wherein the hydrocarbon feedstock is desulfurized. The method of claim 1 or 2, wherein the selective sulfur adsorbent contains CuO, manganese compounds and binders. The method of claim 1 or 2, wherein the selective sulfur adsorbent contains a manganese compound, an iron compound and a large surface area alumina. 7. The calcium ion exchange zeolite of claim 1, wherein the calcium ion exchange zeolite is further selected from the group consisting of zinc, cadmium, cobalt, nickel, copper, iron, manganese, silver, gold, scandium, lithium, and combinations thereof. A method of desulfurizing a hydrocarbon feed, characterized in that it is ion exchanged with selected metal ions, preferably by 1% to 40% of exchangeable metal ions. 8. The method of claim 1, wherein the feed stream is contacted with a calcium ion exchange zeolite prior to contact with the selective sulfur adsorbent. 9. Supplying a hydrocarbon feed stream to a fuel cell processing train, wherein the feed is a sulfur compound such as carbonyl sulfide, hydrogen sulfide, tetrahydrothiophene, dimethyl sulfide, mercaptan, disulfide, thiophene, Contaminated with a sulfur compound containing one or more compounds selected from the group consisting of sulfoxides, other organic sulfides and high molecular weight organic sulfur compounds and combinations thereof, Passing a sulfur-contaminated feed through a series of sulfur adsorbent bed systems containing calcium ion exchange zeolite X and manganese-based selective sulfur adsorbent to produce a substantially desulfurized hydrocarbon feed, wherein the calcium ion exchange zeolite X Is preferably at least 50%, more preferably at least 70% and most preferably 85 to 95% of the exchangeable metal ions exchanged with calcium ions, and Delivering substantially desulfurized hydrocarbon feed to the remaining components of the fuel cell system. 10. The method of claim 9, wherein when the feed stream passes through the series of sulfur sorbent bed systems, the temperature of the series of sulfur sorbent bed systems is between room temperature and 100 ° C. A series of adsorbent bed systems containing selective sulfur adsorbents and calcium ion exchange zeolites for use in fuel cell processing trains, wherein the selective sulfur adsorbents are MnO ₂ , Mn ₂ O ₃ , Mn ₃ O ₄ and Mn (OH) _4. And at least one manganese compound selected from the group consisting of a mixture thereof, iron oxide, and a carrier having a large surface area, wherein the calcium ion exchange zeolite has at least 50% of the exchangeable metal ions ion exchanged with calcium ions, preferably A series of adsorbent bed systems wherein at least 70% of the exchangeable metal ions, at least 70% of which are ion exchanged, contain calcium ion exchange zeolite X ion exchanged with calcium ions. A series of adsorbent bed systems containing selective sulfur adsorbents and calcium ion exchange zeolites for use in fuel cell processing trains, wherein the calcium ion exchange zeolites are more than 50% of exchangeable metal ions ion exchanged with calcium ions. Preferably at least 70% is ion exchanged, and most preferably 85 to 95% of exchangeable metal ions are ion exchanged with calcium ions, the selective sulfur adsorbent being MnO ₂ , Mn ₂ O ₃ , Mn ₃ O _A series of adsorbent bed systems characterized by containing at least one manganese compound, copper oxide and binder selected from the group consisting of ₄ and Mn (OH) ₄ and mixtures thereof. A series of adsorbent bed systems containing two selective sulfur adsorbents and calcium ion exchange zeolites for use in fuel cell processing trains, wherein the calcium ion exchange zeolites have at least 50% of the exchangeable metal ions ion exchanged with calcium cations. More preferably, 85-95% of the exchangeable metal ions, at least 70% of which are ion exchanged, contain calcium ion exchange zeolite X ion-exchanged with calcium ions, the first of the two selective sulfur adsorbents being One or more manganese compounds selected from the group consisting of MnO ₂ , Mn ₂ O ₃ , Mn ₃ O ₄ and Mn (OH) ₄ and mixtures thereof, iron oxide and a carrier of a large surface area, the second of the two selective sulfur adsorbents A series of adsorbent bed systems characterized by containing copper oxide and activated carbon. A series of adsorbent bed systems containing two selective sulfur adsorbents and calcium ion exchange zeolites, wherein the calcium ion exchange zeolites have at least 50% of exchangeable metal cations ion exchanged with calcium cations, more preferably at least 70% 85-95% of these ion-exchanged, most preferably exchangeable metal ions are calcium ion-exchanged zeolite X ion-exchanged with calcium ions, the first of the two selective sulfur adsorbents being MnO ₂ , Mn ₂ O ₃ , Mn ₃ One or more manganese compounds selected from the group consisting of O ₄ and Mn (OH) ₄ and mixtures thereof, iron oxide and a carrier of a large surface area, the second of the two optional sulfur adsorbents containing zinc oxide, copper oxide and alumina Characterized by a series of adsorbent bed systems.

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