JPH0446885B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a process for oxidizing _H2S , and in particular to a process for the catalytic oxidation of _H2S to sulfur in the presence of significant amounts of water vapor. Current air pollution regulations allow emissions into the atmosphere
The amount of H ₂ S is extremely limited. In some cases, a gas stream cannot be discharged to the atmosphere if it contains more than about 10 ppmV of _H2S . Accordingly, many methods have been developed to remove _H2S from gas streams prior to release to the atmosphere. One method known in the art for removing _H2S is catalytic oxidation, i.e., a gas stream containing _H2S is mixed with air or free oxygen, and the resulting mixture is then mixed with the desired _H2S . elemental sulfur vapor or SO ₂
Alternatively, it may be passed through a bed of particulate catalyst under suitable conditions to convert to both. One catalyst useful for the gas phase conversion of _H2S to sulfur or _SO2 is described in U.S. Pat.
It is disclosed in the specification of No. 4092404. The catalyst consists of one or more vanadium oxides or vanadium sulfides supported on a refractory oxide such as alumina or silica-alumina. Another such catalyst is disclosed in U.S. Pat. No. 4,012,486, which describes the catalytic combustion of H ₂ S to SO ₂ using a catalyst having an active component of bismuth. do. By comparison, the bismuth catalyst of US Pat. No. 4,012,486 is generally found to be less active than the vanadia catalyst of US Pat. No. 4,092,404 for oxidizing H ₂ S to SO ₂ . H ₂ ^{S from a gas stream such as the off-gas discharged from a geothermal power plant containing water vapor at a water vapor partial pressure of about 0.07 Kg/cm 2 (} about 1.0 psia), and typically at least 0.28 Kg/cm 2 (4.0 psia). Bismuth catalysts are more stable than vanadia catalysts at operating temperatures below about 316°C (600°C). Generally, vanadia catalysts have satisfactory stability in the presence of water vapor at partial pressures below about ^1.0 psia or operating temperatures above about 600°C, but (600〓) or below and approx.
0.07Kg/cm ² (approximately 1.0psia) or more, especially 0.105Kg/cm ²
(1.5 psia) or higher, the vanadia catalyst rapidly deactivates.
The reason for this deactivation is believed to be due to a complex series of chemical reactions in which the vanadium oxide or vanadium sulfide active catalyst components are converted to less active forms of vanadium, such as vanadyl sulfate (VOSO ₄ ). As mentioned above, vanadia catalysts are highly active for the oxidation of H ₂ S and are known as U.S. patent application Ser.
Such catalysts have proven extremely useful for oxidizing H ₂ S to sulfur by reaction with either oxygen or SO ₂ , as disclosed in . In the presence of water vapor below about 0.07 Kg/cm ² (about 1.0 psia), vanadia catalysts are extremely stable and can convert H ₂ S to sulfur for over a year with only slight deactivation. Can be done. However, despite the excellent properties of this vanadium catalyst, the objective of the present invention is not only to improve the stability of vanadium-containing catalysts in the presence of water vapor, but also to significantly improve the activity of converting _H2S to sulfur. There is a particular thing. More particularly with regard to water vapor, the object of the present invention is ^to
(approximately 1.0psia) or more, especially approximately 0.105Kg/cm ² (approximately
1.5 psia) and more particularly approximately 0.14 Kg/cm ² (approximately 2.0 psia)
The object of the present invention is to provide a method for catalytically oxidizing H ₂ S in the presence of water vapor at a partial pressure above. Further, the purpose of the present invention is to
The aim is to achieve the method without oxidizing components such as H ₂ , CO, NH ₃ and CH ₄ that may be present during the oxidation of H ₂ S. Catalysts containing bismuth and vanadium components are
We confirmed that it is highly active and stable for gas-phase oxidation of hydrogen sulfide, especially in the presence of water vapor. Such catalysts have the high activity of vanadia catalysts and the stability of bismuth catalysts. Furthermore, it has been found that the catalysts of the present invention are generally significantly more stable in the presence of water vapor than catalysts containing bismuth or vanadium alone, particularly at operating temperatures below about 316°C (600°C). The catalyst of the present invention is effective when H ₂ S must be oxidized in the gas phase in the presence of water vapor at partial pressures greater than about ^1.0 psia. Since an equal volume of water vapor is produced for each volume of H ₂ S that is converted from H ₂ S to sulfur or SO ₂ , the water vapor partial pressure of the feed gas is initially about 0.07 Kg/cm ² (about 1.0 psia). less than 0.07Kg/cm ² while in contact with the catalyst
The present invention is useful for processes where the pressure increases above (1.0 psia). An advantage of the invention is the high selectivity of the catalyst. Components selected from the group consisting of H ₂ , CO, NH ₃ and saturated hydrocarbon gases having up to 6 carbon atoms (ie, light hydrocarbons) are not oxidized in the process of the present invention. In addition, the oxidation of H ₂ S is approximately 482℃
(approximately 900〓) or below, almost no SO ₃ is generated. Furthermore, and quite strikingly, vanadium-bismuth catalysts were found to be more active than comparable vanadia catalysts for converting _H2S to sulfur. This finding was clearly surprising since the vanadia catalyst itself is highly active in converting H ₂ S to sulfur. However, comparable vanadium-bismuth catalysts were found to have not just greater activity than vanadia catalysts, but significantly greater activity. For example, as shown in Example 6 below, a prior art vanadia catalyst containing about 10% by weight of vanadium pentoxide supported on silica alumina releases sulfur at a temperature of about 191°C (about 375°C). A vanadium-bismuth catalyst active but with the same support but containing 8.7% by weight vanadium component and 12.9% by weight bismuth component to initiate the reaction between the H ₂ S produced and oxygen is heated at 149°C (300°C). 〓) It can be seen that it is active to initiate the reaction of converting H ₂ S to sulfur at the following temperatures. Here, the catalyst containing vanadium and bismuth or the catalyst containing vanadium and bismuth components refers to (1) vanadium element and bismuth element, (2) vanadium element and one or more bismuth compounds, (3) bismuth element and one or more vanadium compounds; (4) one or more vanadium compounds and one or more bismuth compounds; (5) one or more bismuth and vanadium compounds (e.g. vanadium). _bismuth acid), or (6) a combination of any of the foregoing. The active catalyst used in the present invention contains vanadium and bismuth as essential active components. The essential active ingredients are present as the elements V and Bi or as mixtures of vanadium and bismuth individual compounds (e.g. Bi ₂ S ₃ mixed with V ₂ S ₅ ) or as compounds of bismuth and vanadium, e.g. Bi(VO ₃ ) May exist as ₃ or _BiVO4 . Or again,
Contains any combination of vanadium and bismuth elements and compounds as essential active components of the catalyst. Preferred catalysts include at least one vanadium oxide or sulfide (e.g. V ₂ O ₅ , V ₂ O ₃ , V ₂ S ₅ ,
and V ₂ S ₃ ), and at least one bismuth oxide or bismuth sulfide (e.g., BiO, Bi ₂ O ₃ ,
Bi ₂ O ₅ , Bi ₂ S ₃ and Bi ₂ O ₄ ). The most preferred catalysts are _{at least some bismuth vanadate (i.e., as orthovanadate, BiVO4 or Bi2O3V2O5, metavanadate Bi(VO3)3 , or pyrovanadate Bi4 ( V2 ) .} O ₇ ) including ₃ ). Typical catalysts include vanadium and bismuth components in an intimate mixture, and although the catalyst can consist primarily of such a mixture, it is possible to mix the vanadium and bismuth components with a carrier material, such as by impregnation or kneading. Highly preferred. Common carrier materials include, for example, alumina-silica, zirconia, titania, magnesia,
Composed of porous refractory oxides, including preferred refractory oxides such as silica-alumina, silica-zirconia, silica-titania, silica-magnesia, silica-zirconia-titania, and combinations thereof. Suitable refractory oxides include acidic metal phosphates and arsenates such as aluminum phosphate, boron phosphate, aluminum arsenate, chromium phosphate, and the like. Other suitable supports include hydrophobic crystalline silica, such as the silicalite described in U.S. Pat. A refractory oxide is hydrophobic if it can absorb Also suitable are natural or synthetic amorphous and crystalline aluminosilicate zeolites. The most useful crystalline aluminosilicate zeolites are ion-exchange treated to remove nearly all ion-exchangeable alkali or alkaline earth components. Particularly useful are hydrophobic crystalline alumino-silicates containing almost no alkali or alkaline earth components. An example of such a zeolite is ZSM disclosed in U.S. Pat. No. 3,702,886.
-5 zeolite, the ZSM-11 zeolite disclosed in U.S. Pat. No. 3,709,979, and the hydrophobic zeolite disclosed in U.S. Pat. No. 4,019,880. This type of zeolite is characterized by a high silica to alumina ratio. The most preferred refractory oxide support is silica-alumina when the alumina is present in a proportion of at least 10% by weight, preferably about 20-30% by weight. Catalysts prepared from this type of support typically exhibit higher H ₂ S
It has great activity for oxidizing. Furthermore, such supports are highly resistant to sulfation, i.e. SO ₃
and/or in the presence of SO ₂ and O ₂ , such supports are less susceptible to the formation of aluminum sulfate and the resulting loss of surface area, crushing force and activity. In general, catalysts prepared using silica-alumina supports containing at least 10% by weight alumina are expected to experience little deactivation due to sulfation under the processing conditions described below. Several methods are known in the art for combining vanadium and bismuth components with refractory oxide supports.
One such method is impregnation. i.e. 75%
Ammonium vanadate (or other soluble vanadium compound) with a suitable support such as SiO ₂ -25% Al ₂ O ₃ silica-alumina pellets or extrudates.
in contact with the solution and at high temperature (usually about 110℃ (230〓))
and then contacted with a bismuth salt solution, such as an acidic solution of bismuth nitrate or bismuth chloride. The composite can also be prepared by any of a variety of kneading techniques. A typical method is to knead silica alumina with solid ammonium metavanadate, solid bismuth nitrate, and sufficient water to create a paste suitable for extrusion through a mold.
More preferably, one or both of the vanadium and bismuth salts can be added to the kneaded material in the form of a solution. In a preferred embodiment, a silica-alumina mixture, a dilute nitric acid solution of bismuth nitrate, and an aqueous solution of ammonium metavanadate are kneaded. Alternatively, the silica-alumina or other refractory oxide is kneaded with, for example, an ammonium metavanadate solution, then dried or calcined at high temperature, and then kneaded with an aqueous solution of a bismuth salt, such as bismuth nitrate in dilute nitric acid. It can also be carried out by mixing kneaded silica-alumina and one or more types of bismuth vanadate in the presence of water. Furthermore, the composite can be prepared by a combination of impregnation and kneading techniques, such as impregnating silica-alumina with ammonium vanadate, calcining, and then kneading with an acidic solution of bismuth nitrate or bismuth chloride. After the composite is prepared by any of the impregnation and/or kneading methods described above or a method equivalent thereto, it is typically heated at a temperature of about 371° to about 871°C (about 700° to about
1600〓), preferably 482゜~649℃(900゜~1200゜
Calcinate at a temperature of 〓). Calcination produces a catalyst containing vanadium and bismuth mostly in oxide form, but calcination between 371° and 871°C (700° and 1600°) typically produces enough vanadium to be detected by X-ray diffraction analysis. Bismuth acid is usually produced in the form of monoclinic bismuth orthovanadate (BiVO ₄ ). Bismuth orthovanadate and other bismuth vanadates are commonly formed even when impregnating or kneading without careful addition of bismuth vanadate. For example, silica-alumina is kneaded with ammonium metavanadate (example), then further kneaded with an acidic solution of bismuth nitrate, extruded, cut into particles, and calcined at 482°-538°C (900°-1000°). If so, the final product contains sufficient bismuth orthovanadate to be detected by X-ray diffraction analysis. Although the present invention is not limited to, catalysts containing bismuth vanadate are more active and stable than catalysts without bismuth vanadate. This is particularly true for bismuth orthovanadate ( _BiVO4 ).
This applies to Further, the reason why the stability of the catalyst is higher in the presence of water vapor than in the case of a catalyst containing only a vanadium component or only a bismuth component is considered to be due to the presence of bismuth vanadate. Catalysts containing bismuth vanadate, especially bismuth orthovanadate, are therefore preferred according to the invention. The finished catalyst can contain any content of vanadium and _bismuth , but preferably contains at least 5.0% by weight vanadium and 5.0% by weight _bismuth , calculated as _V2O5 and _Bi2O3 , respectively. Catalysts containing less than 5.0% by weight of either metal are more active or stable than catalysts containing only either vanadium or bismuth components, but with at least 5.0% by weight of each component.
Somewhat less active and stable than containing catalysts. The catalyst preferably contains 5 to 15% of each component, and can contain up to 40% by weight of each component as required.
One suitable catalyst is one in which vanadium is present at least 7% by weight, calculated as V ₂ O ₅ and bismuth is present.
It may include a supported vanadium and bismuth composition present in an amount of 8-20% by weight calculated as Bi ₂ O ₃ . Highly preferred catalysts contain about 7-15 wt.% vanadium as _V2O5 and about 8-20 wt.% bismuth as _Bi2O3 , and most preferred _{catalysts contain} at least _8.0 wt.% vanadium component as _V2O5 . and at least 10% _by weight as _Bi2O3
containing a bismuth component of (all calculations regarding the proportion of the active metal component of the catalyst are V ₂ O ₅ and
Weight% of vanadium and _bismuth as _Bi2O3
was recorded. Therefore, 5 g containing elemental vanadium, elemental bismuth, bismuth sulfide (Bi ₂ S ₃ ), vanadium sulfide (V ₂ S ₅ ), and bismuth orthovanadate (BiVO ₄ ) each weighing 0.1 g.
Catalyst particles weighing _5.52 % by weight as _V2O5 and 5.48 _% as _Bi2O3
% by weight of bismuth components). The following two examples demonstrate preferred methods of preparing catalysts useful in the present invention. Example: Davison Chemical Division of Dubrill as a high alumina cracking catalyst.
421 g of 75% SiO ₂ -25% Al ₂ O ₃ silica-alumina commercially available from Earl Grace & Company was placed in a steel miller, and 44.2
g of ammonium metavanadate (NH ₄ VO ₃ )
and 6 g of powdered methylcellulose were added.
The mixture was kneaded for 45 minutes. Then 200c.c. of water and 32
A solution was prepared by dissolving 88.8 g of bismuth nitrate (Bi(NO ₃ ) ₃ 5H ₂ O) in a liquid consisting of cc of concentrated nitric acid. Add this solution to the previously kneaded mixture and mix for 15 minutes.
Kneading was continued for a minute. It was then mixed with 71 c.c. of water for 15 minutes to produce an extrudable paste. Then,
The resulting paste is extruded through a 3.2 mm (1/8 inch) diameter die, approximately 3.2 to 12.7 mm (approximately 1/2
The particles were cut into ~1/2 inch) long particles. The extrudates were dried overnight at a temperature of 110°C (230°C). It was then calcined in air at a temperature of 500°C (932°C) for 2 hours. The resulting catalyst contained a vanadium component of 9.1% by weight as V ₂ O ₅ and a bismuth component of 11.2% by weight as Bi ₂ O ₃ . The catalyst contained X-ray detectable amounts of bismuth orthovanadate. EXAMPLE A sufficient amount of ammonium metavanadate (NH ₄ VO ₃ ) was mixed with the high alumina silica-alumina described in the previous example. 3.2mm after extrusion
(1/8 inch) diameter, cut into 1.6-12.7 mm (1/16-1/2 inch) cylindrical extrudates and calcined at a temperature of about 500 °C (932〓) in air for 2 hours. did. The product obtained contained a vanadium component of 10% by weight as V ₂ O ₅ . 35g bismuth nitrate (Bi
(NO ₃ ) ₃・5H ₂ O) was dissolved in a mixture of 100 c.c. of water and 15 c.c. of concentrated nitric acid, and water was added to this to make 120 c.c., and 100 g of the above was brought into contact with the product of
The solution was left in contact with the extrudate for 2 hours to ensure complete impregnation. The extrudates were then filtered, dried overnight at 110°C (230°) and calcined at 500°C (932°) for 2 hours in the presence of air. The resulting catalyst contains an X-ray detectable amount of bismuth orthovanadate and further contains
8.63 wt% vanadium component as _{V2O5 and}
It contained 11.6% by weight of bismuth component as Bi ₂ O ₃ . It has been found that catalysts prepared by the above methods or clearly corresponding methods are highly active for gas phase oxidation of H ₂ S to optionally SO ₂ , sulfur or a combination of both. Furthermore, such catalysts
In the temperature range of 121°~482°C (250°~900〓), SO ₃
selectively oxidizes H 2 S without producing _much or without oxidizing light hydrocarbons that can coexist with H ₂ , CO, NH ₃ or H ₂ S. Of particular importance is that the catalyst is extremely stable in the presence of water vapor. A catalyst that oxidizes H ₂ S at temperatures below about 316°C (about 600°C) in the presence of water vapor at a partial pressure of about 0.07 Kg/cm ² (about 1.0 psia) or more has a lifetime of at least 90
days, usually at least one year. In particular, the catalyst has a water vapor partial pressure of at least 1.5 ^psia , preferably at least 4.0 ^psia , and especially ^up to about 10.0 psia. It is effective in oxidizing H ₂ S under pressure. For valid results, approximately 0.63Kg/cm ² (approximately
approximately 193℃ in the presence of water vapor at a partial pressure of 9.0psia)
H ₂ S is converted to elemental sulfur by reacting with oxygen at a temperature of (380〓). The choice of whether to convert H ₂ S in a given gas stream to elemental sulfur or SO ₂ depends in large part on local air pollution regulations. Typically, the maximum concentration of _H2S that can be vented to the atmosphere is about 10 ppmV, while _SO2 can be vented at a maximum concentration that varies from about 500 ppmV to 2.0% by volume. Therefore, the combustion of _H2S , i.e., the conversion of _H2S to _SO2 , is typically carried out on a gas stream containing about 10 ppmV to 2.0% by volume of _H2S , which is treated for conversion to elemental sulfur. Typical gas flow is at least about 500 ppmV
_H2S , typically 500ppmV to 10.0% _H2S by volume, preferably 50ppmV to 5.0% by weight _H2S , optimally
Contains 500ppmV~2.0% _H2S by volume. That is, the gas stream treated in the method of the invention is H ₂ S
In addition to N ₂ , CO ₂ , CO, H ₂ , SO ₂ , O ₂ , Ar,
Contains any of the components such as NH ₃ , H ₂ O and light hydrocarbons. Typical gas streams treated here are sour natural gas, geothermal steam off-gas, and _H2S -containing gas streams such as hot-gasified coal or gasified residues. The gas stream may also contain sulfur-containing components such as COS, CS ₂ and light mercaptans (ie, saturated mercaptans containing 6 or fewer carbon atoms). If such sulfur-containing components are present, it is preferred to pretreat the gas stream by the method disclosed in US Pat. No. 3,752,877. According to this method, CS ₂ ,
COS and light mercaptans together with SO ₂ if SO ₂ is present at high temperature (typically 149° to 538°C).
(300° to 900〓)) containing one or more effective catalyst components from Co, Mo, Fe, W, and Ni, preferably
In the presence of a catalyst comprising a combination of Co and Mo or Ni and Mo, it is simultaneously converted to _H2S by reaction with _H2 and/or water vapor. This pretreated gas stream contains _H2S as almost the only gaseous sulfur component;
H ₂ S can be treated by the method to convert it to the desired SO ₂ and/or elemental sulfur. A particularly suitable gas stream for the pretreatment method is Krauss tail gas. Other gas streams which are preferably pretreated before being contacted with the catalyst of the invention are gas streams containing olefins or aromatic hydrocarbons.
Olefins deactivate the catalyst by forming gums that precipitate on the catalyst surface, and aromatics such as benzene are present in significant amounts (e.g. 100 ppmV) when the operating temperature is below about 177°C (about 350°C). Deactivates the catalyst. However, these two types of deactivation are only temporary; olefin deactivation can be overcome by high temperature oxidation of the gum-containing catalyst, and aromatic deactivation can be overcome by increasing operating temperatures above 177°C (350°C). be overcome by raising it. It is also preferred to preheat the gas stream containing aromatic or olefinic components before contacting it with the catalyst of the invention to remove these harmful components. One pretreatment method particularly suitable for gas streams containing olefins is SO ₂ , CS ₂ ,
Catalytic hydrogenation with the catalyst and conditions specified for the gas stream containing COS and light mercaptans. The gas stream to be combusted must contain or contain enough oxygen to provide at least the stoichiometric amount required for the reaction: 2H ₂ S + 3O ₂ →2SO ₂ +2H ₂ O suitable oxygen or air should be mixed. Additionally, in excess of the stoichiometric amount, typically about 1.1 to 1.1 of the stoichiometric amount.
Preferably, oxygen is present in 2.5 times the amount. Other conditions typically used to combust _H2S in an adiabatic or isothermal reactor are: ( ^a ) 5-500 psia, preferably 15-75 ^psia ; ) operating pressure, (b) 121° to 538°C (250° to 900°), preferably about
316℃ (600〓) or less, particularly preferably about 232℃
(450〓) or less inlet operating temperature, (c) 100~50000v/v/hr, preferably 500~
The space velocity is 5000v/v/hr. The operating conditions are suitably adjusted to convert at least 90% of the _H2S to _SO2 . Preferably, by adjusting the operating conditions
Almost all of the H ₂ S is converted. Almost all _H2S
The conditions for conversion to SO ₂ are 232℃ (450〓), 3.5
Kg/cm ² (50psia), 2000v/v/hr (16℃ (60〓)
(gas volume calculated at ), a stoichiometric amount of 2.2 air and 2700 ppmV H ₂ S in the feed gas.
The following examples demonstrate the suitability of these conditions. Example A feed gas flow having the composition shown in Table 1 was
460scc/min (16°C
Mix at a speed of (gas volume measured at 60〓). Water vapor content 7.7% by volume and oxygen content approximately 0.80
% by volume (2.23 times the stoichiometric amount) for 15 days at a pressure of 3.5 Kg/cm ² (50 psia), a constant temperature of 232 °C (450 °C) and a temperature of about 2000 v/v/
hr space velocity through an isothermal catalytic reactor containing 15 c.c. of catalyst particles consisting of 11.6 wt.% bismuth component (as Bi ₂ O ₃ ) and 8.6 wt. % vanadium component (as V ₂ O ₅ ). . The catalyst was prepared as described in the example, and the water pressure in the reactor was 3.5 Kg/cm ²
(50 psia). The product gas was analyzed on day 15 by suitable mass spectrometry techniques and the results are shown in Table 1 on an anhydrous basis. As shown in Table 1, H ₂ S
is completely converted to SO ₂ and no H ₂ or methane is oxidized. The SO ₃ content of the effluent gas is 3~
It was 5.0ppm.

【table】

[Table] Example The six types of catalysts prepared were tested under the conditions of the example, and H ₂ S was burned at a water vapor pressure of 3.5 Kg/cm ² (50 psia) to determine how active and stable they were. did. Six catalysts were prepared as follows. A mixture of the high alumina cracking catalyst and ammonium vanadate described in the 10 wt% V ₂ O ₅ Example on Silica Alumina was kneaded with a sufficient amount of water to form a paste suitable for extrusion. Extrude this paste into a 3.2 mm (1/3 inch) die, approximately 1.6 to 12.7 mm (1/16 to 1/2 inch).
Cut into lengths, dry at 110℃ (230〓), and dry at 500℃.
Calcined in air at 932 °C for 2 hours. The catalyst contains 10% by weight vanadium component (calculated as V ₂ O ₅ )
and silica-alumina (75% silica-25% alumina). 36.6 wt% V ₂ O supported on silica-alumina ₅ 291 g of high alumina silica-alumina, 108 g of ammonium metavanadate, and 7.74 g of methylcellulose described in Example 1 can be kneaded with sufficient water and extruded. I made a paste. Then extrude the paste to 3.2mm (1/3 inch)
diameter, cut into cylindrical pieces 1.6-12.7 mm (1/16-1/2 inch) long. Leave this in the air for 2 hours
Calcined at 110℃ (230℃). The catalyst thus produced was silica-alumina (75% _SiO2-25 %
36.6 wt% vanadium component ( _{V2O5 )} on top _{of Al2O3} )
(calculated as ). 10.2 wt% Bi ₂ O ₃ on Alumina This catalyst was prepared in a manner similar to that described in the Examples of US Pat. No. 4,012,486. The method used is as follows. 17g BiCl ₃ to 40c.c.
of water and added 40 c.c. of concentrated hydrochloric acid. The solution was then diluted with 100 c.c. of water. The solution thus obtained was mixed with 100 g of gamma alumina 1.6 mm for 2 hours.
(1/16 inch) diameter extrudate.
Excess solution was decanted off and washed with a solution of 30% concentrated NH ₄ OH and 70% water until chloride-free. It was then washed with 500 c.c. of water and calcined at 500° C. (932°) for 2 hours. The catalyst contained 10.2% bismuth component (calculated as Bi ₂ O ₃ ) supported on gamma alumina. 4.5 wt% Bi ₂ O ₃ − supported on silica alumina
9.4 wt% _V2O5 This catalyst was obtained by first preparing ₁₀ wt% _V2O5 supported on silica-alumina as described _above .
First, 5 c.c. of concentrated nitric acid was added to 100 g of this catalyst.
It was contacted with a solution prepared by dissolving 11.6 g of bismuth nitrate in 100 c.c. of water and adding enough water to bring the solution to 120 c.c. The contact time was 2 hours.
The excess liquid was then decanted off. The impregnated extrudates were then dried at 110°C (230°) overnight and calcined at 500°C (932°) for 2 hours in air. The final catalyst contains 4.5% by weight bismuth component (Bi ₂ O ₃
(calculated as _V2O5 ) and 9.4% by weight of vanadium content (calculated as _V2O5 ). The final catalyst was determined to contain bismuth orthovanadate by X-ray diffraction analysis. 7.95 wt% Bi ₂ O ₃ − supported on silica alumina
9.0 wt% V ₂ O ₅ This catalyst was prepared as follows except 4.5 wt % Bi ₂ O ₃ - 9.4 wt % V ₂ O ₅
Prepared in the same way as the catalyst. Added 10 c.c. of nitric acid
23.2 g of bismuth nitrate was dissolved in 100 c.c. of water.
The solution was then sufficiently diluted with water to a total volume of 120 c.c. _The final catalyst contained 7.95 wt% bismuth component (as _Bi2O3 ) and 9.0 _wt % vanadium component (as _V2O5 ). The catalyst contained bismuth orthovanadate by X-ray diffraction analysis. 11.6 wt% Bi ₂ O ₃ − supported on silica alumina
8.63% by weight V ₂ O ₅ This catalyst was prepared by the method given in the Examples. H ₂ S was combusted to SO ₂ using each of the catalysts described above under the conditions listed in the Examples. The only condition that varied for each catalyst was the operating temperature. Approximately 232° ~ 266°C
After operating with various catalysts for several days while changing the temperature in the range of (450° to 510°), the concentration of unreacted _H2S in the gas sample produced at a specific operating temperature in the early stage of the experiment and that in the late stage of the experiment were determined. The stability of each catalyst was determined by comparing the concentration of unreacted _H2S in a gas sample produced at the same specific temperature. The data thus obtained are summarized in Table 2. The stability of various catalysts with respect to the increase in unreacted H ₂ S in the product gas per day is also summarized in Table 2. The most stable catalysts consist of bismuth components or bismuth and vanadium components as the main active catalyst components.
Catalysts containing only a vanadium component as the major active catalyst component deactivated at an unacceptably high rate.
The most stable catalysts contain at least about 8.0% by weight bismuth and 7.0% by weight vanadium components. This type of catalyst was found to be significantly more stable than the 10% or 36.6% V ₂ O ₅ catalyst and twice as stable as the 10% Bi ₂ O ₃ catalyst. Two catalysts containing at least about 8.0 wt.% bismuth component and at least about 7.0 wt.% vanadium component lower the _H2S concentration in the product relative to a vanadium-bismuth catalyst containing only 4.5 wt.% bismuth. Compared to about 6ppmV, about
The fact that it remains below 3.5 ppmV is important. _H2S released into the atmosphere due to many environmental controls
Can be below 10ppmV, at least about
Two vanadium-bismuth catalysts containing 8.0 wt% bismuth provide activity and stability so that _H2S in the product gas reaches high levels;
The 4.5% bismuth-9.4% vanadium catalyst proves to be somewhat less suitable for this purpose. especially,
The stability of the 11.6 wt% bismuth-8.63 wt% vanadium catalyst is high. Due to the high stability and high activity of this catalyst, this catalyst is combined with a bismuth component of at least 10% by weight calculated as Bi ₂ O ₃ and a vanadium component of at least 8.0% by weight calculated as V ₂ O ₅ Other catalysts containing are most preferred in the present invention.

Table: Example Data comparing the initial activity of the catalyst of the invention with the prior art and the H ₂ S produced obtained at various temperatures in the example experiments before the critical catalyst deactivation. are summarized in Table 8. The data summarized in Table 3 was obtained by experimenting under the same conditions as in the example, but with 13.0% by weight of Bi ₂ O ₃ and silica-alumina (75% by weight).
% _SiO2-25 % _Al2O3 ) was used _. The catalyst was obtained by impregnating a silica-alumina extrudate with a bismuth nitrate solution and then calcining it in air at 500°C (932°C) for 2 hours.

【table】

[Table] As shown in Table 3, vanadia and vanadium
The activity of bismuth catalysts was compared under experimental conditions with almost no unreacted _H2S at temperatures of 216° to 232°C (420° to 450°C). On the other hand, 10.2% and 13.0 bismuth catalysts have approx.
It was effective only at temperatures above 260°C (500°C).
At temperatures between 254° and 260°C (490° and 500°C), both bismuth catalysts exhibit unreacted temperatures as high as 50 ppmV.
Showed no activity with H ₂ S. Therefore, catalysts containing vanadia and vanadium-bismuth demonstrate substantially superior activity in converting H ₂ S to SO ₂ over catalysts containing only the bismuth component as the main active catalyst component. Ta. The catalyst of the present invention can also be used to oxidize H ₂ S to elemental sulfur and combust it to SO ₂ .
The conditions for producing elemental sulfur are usually selected from the following range for an adiabatic or isothermal reactor: 121°~
482℃ (250゜~900〓), 10~10000v/v/hr,
0.35-5.27Kg/ ^cm2 (5-75psia), preferably 135°-246°C (275°-475〓), 200-2500v/v/hr and 1.05-2.11Kg/ ^cm2 (15-30psia), optimal for
135~218℃ (275゜~425〓), 500~1500v/v/
hr, and 1.05-1.41 Kg/ ^cm2 (15-20 psia). Additionally, the inlet temperature is preferably maintained below about 204° C. (400°), and optimally below 177° C. (350°), to convert at least some H ₂ S to elemental sulfur below that temperature. An oxidizing gas is also required, and oxygen, usually supplied in air, is mixed with the supplied gas stream to produce sulfur vapor by the reaction represented by the following equation (2): 2H ₂ S + O ₂ → 2S + 2H ₂ O do. The amount of air or oxygen mixed with the feed gas is most preferably such that oxygen is present in a stoichiometric amount or a near stoichiometric amount for reaction equation (2);
Usually about 0.9 to 1.1 times the stoichiometric amount. As is well known, maximum conversion of H ₂ S to sulfur is achieved when oxygen is available in stoichiometric amounts. High yields of sulfur are provided by low water vapor partial pressures and below about 24.6°C (475〓), especially about 232°C.
(450〓) and below, the sulfur yield increases with decreasing temperature and decreasing water vapor partial pressure. Of course, SO ₂ can be used in place of oxygen to convert H ₂ S to sulfur, and sulfur is produced according to the following reaction equation. (3) 2H ₂ S + SO ₂ →3S + 2H ₂ O Therefore, if SO ₂ is present in the feed gas stream where the H ₂ S to SO ₂ ratio is greater than 2.0, it will be combined with unconverted H ₂ S according to reaction equation (3). Oxygen is added in the required amount in an amount sufficient for the reaction. That is, the _H2S to _SO2 ratio is 2.0
If larger, the stoichiometric amount of oxygen is sufficient to give a molar or volume ratio of H ₂ S to (SO ₃ +O ₂ ) equal to 2.0. For feed gas streams naturally containing _H2S and _SO2 with a _H2S to _SO2 ratio of less than 2.0, high conversion to sulfur can be achieved by first using the method described in U.S. Pat. No. 3,752,877. Thus, the feed gas is pretreated to convert SO ₂ to H ₂ S, and the pretreated gas is then treated with oxygen or air in an amount sufficient to give a H ₂ S to O ₂ ratio equal to 2.0. Mix. No pretreatment or oxygen addition is required for the feed gas containing a _H2S to _SO2 ratio equal to 2.0. A catalyst can be used to directly convert H ₂ S to sulfur according to reaction equation (3). In view of the foregoing, SO ₂ can be used as the oxidizing agent in place of oxygen if elemental sulfur is desired. That is, for a gas stream containing H ₂ S, here elemental sulfur is added by mixing either SO ₂ or an oxygen oxidizer with the gas stream to give an H ₂ S to oxide ratio of 2.0. can be generated.
However, it is readily available in the form of air,
Also, due to the high conversion rate to sulfur, oxygen is naturally
Better than SO ₂ . Comparing reaction formulas (2) and (3), the amount of H ₂ S converted to sulfur is the same, but
Equation (3) using SO ₂ oxidizer produces 50% more sulfur than Equation (2) using O ₂ oxidizer. By equation (3)
To produce 50% more sulfur, equation (3) requires a higher operating temperature than equation (2), provided the sulfur vapor dew point is not exceeded. However, at operating temperatures below 538° C. (1000°), the conversion of H ₂ S to sulfur decreases with increasing temperature. Therefore, without exceeding the dew point, equation (3)
When using oxygen as the oxidizing agent, there is an inherent advantage over using SO ₂ , namely a higher conversion rate, since H ₂ S can be converted to sulfur according to equation (2) at lower temperatures. When oxygen or _SO2 is used as the oxidizing agent, the catalyst of the present invention is highly useful for converting _H2S to elemental sulfur. The conversion rate at a given condition is
This will, of course, depend on factors such as operating temperature, operating pressure, water vapor partial pressure and choice of oxidizing agent. However, the vanadium-bismuth catalysts described above usually convert _H2S to elemental sulfur within 10% of the theoretical amount, often within 5%. Furthermore, since the vanadium-bismuth catalyst of the present invention has a high activity for converting H ₂ S to sulfur,
Prior art catalysts, such as U.S. Patent Application No. 700,513 filed June 28, 1976 (U.S. Pat.
H ₂ S at lower operating temperatures and/or higher space velocities than the vanadia catalyst disclosed in
is converted to sulfur at a high conversion rate. The following examples demonstrate the high activity of vanadium-bismuth catalysts for the oxidation of _H2S to elemental sulfur. Example 8.7% by weight vanadium component as V ₂ O ₅ ;
A catalyst was prepared in which the support consisted of silica-alumina containing 12.9% by weight of a bismuth component as Bi ₂ O ₃ and the remainder containing 25% by weight of alumina.
This catalyst is in the form of particles with a surface area of 239 m ² /g,
The compact bulk density was 0.67 g/cc. (This catalyst was prepared in a manner very similar to that described in the Examples). The above catalyst (950 g) was charged into an isothermal reactor, and approximately
Concentrations varying from 750ppmV to 1200ppmV
A feed gas containing _H2S and approximately 99% _CO2 (on an anhydrous basis) was used to process. Elemental sulfur produced in the reactor was removed in vapor form and recovered by condensation. The experiment was conducted for a period of more than 5 months, and samples of the supplied gas and produced gas were analyzed under the operating conditions shown in Table 4, and the data are summarized in Table 4. For the experiments described above, except when the operating temperature drops below the sulfur vapor dew point temperature and sulfur precipitates on the catalyst,
It is noteworthy that the catalyst shows no deactivation during the experiment. However, this type of deactivation is only temporary;
The activity of the catalyst is fully restored by the high temperature. As shown by the data in Table 4, the vanadium-bismuth catalyst of the present invention is active to initiate the conversion of _H2S to sulfur at temperatures below 149<0>C. This result is surprising for a number of reasons.
Comparable conventional catalysts...and catalysts known to be highly active in converting _H2S to elemental sulfur, i.e. 75% SiO2 _- 10% _V2O on 25% _Al2O3 support _{. Five}
The supported catalyst is approximately 0.05Kg/cm ²
Its activity is not at all surprising since it begins to oxidize H ₂ S to sulfur only in the presence of water vapor at temperatures above about 135°C (275°C) at hydrogen partial pressures below (0.7 psia). Thus, the catalyst of the present invention has been demonstrated to be significantly more active than a comparable vanadia catalyst in converting _H2S to elemental sulfur, and furthermore, the catalyst of the present invention has been demonstrated to be significantly more active than a comparable vanadia catalyst in converting H2S to elemental sulfur, and further improves the aforementioned experiments by approximately 0.18-0.35 Kg/ ^cm2 (2.5 This is surprising when one considers the fact that the work was done with water vapor at a partial pressure of ~5.0 psia). An increase in the amount of water vapor increases the amount of water vapor absorbed on the catalyst surface, thereby increasing the amount of H ₂ S and
It tends to reduce O ₂ (or SO ₂ ) absorption and increase the onset temperature for the catalyst. But 0.21
Despite the conflicting conditions of Kg/cm ² (3.0 psia) of water vapor, the catalyst of the present invention
It is still active to initiate the reaction between H ₂ S and oxygen, whereas a comparable vanadia catalyst under more favorable conditions of less than 0.05 Kg/cm ² (0.7 psia) of steam is approximately 191°C (375 〓 ) or above. Another surprising aspect of the present invention, as shown by the data in Table 4, is the high stability of the vanadium-bismuth catalyst in the presence of water vapor. As shown in the data in Table 2, vanadia catalysts are rapidly deactivated in the presence of water vapor at temperatures below about 316°C (600°C);
The data in Table 4 covers a period of five months or more.
Vanadium-bismuth catalysts have also been shown to resist this type of deactivation when used in the presence of ^2.5-5.0 psia of water vapor.

[Table] Example This example compares the reaction initiation characteristics of a vanadium-bismuth catalyst and a vanadia catalyst for oxidizing H ₂ S to sulfur. Two types of catalysts were prepared and both were supported on a support mainly composed of silica-alumina (75% SiO ₂ and 25% Al ₂ O ₃ ). The first catalyst is a vanadia catalyst containing a vanadium component of 16.4% by weight calculated as V ₂ O ₅ and the second catalyst contains a vanadium component of 9.7% by weight calculated as V ₂ O ₅ and Bi ₂ Contains 11.2% by weight of bismuth component, calculated as _O3 . Both catalysts were prepared in air-calcined form. Oxygen oxidation was performed using the same feed gases, in which the catalysts were placed in virtually the same container but separately and then simultaneously tested in a parallel operating regime and treated under approximately identical conditions of pressure and weight hourly space velocity. The differences between two catalysts for the reaction of H ₂ S to sulfur using a chemical agent were determined. The feed gas and oxidant blend was H ₂ S at 39.60 scc/min, air flow at 94.28 scc/min, and nitrogen at 1845.82 scc/min;
This provided a feed gas-oxidant gas stream based on 2.0 mole percent _H2S , 1.0 mole percent free oxygen, and about 97.0 mole percent nitrogen flowing at a rate of 1979.70 scc/min. The use of independent control valves allows the flow rate of gas flow into each reaction vessel to be approximately 989.85 scc/
Maintaining as close as possible to the same speed of minutes, the operating pressure maintained in both reaction vessels is approximately 1.03 Kg/cm ²
(14.7 psia). Although the same weight of catalyst, i.e. 1.50 g, was used in the experiment, due to the density difference, the vanadium-
The capacity of the bismuth catalyst was only 2.0 cc compared to 3.0 cc of the vanadia catalyst. Therefore, both catalysts were used under conditions of substantially the same space velocity as measured by catalyst weight, i.e. 39515 volumes (cm ³ ) of gas per gram of catalyst per hour, but on a volume basis. As, the gas velocity per hour for vanadium-bismuth catalyst is more than that for vanadia catalyst.
It was 1.5 times larger. More specifically, the volumetric hourly space velocity for the vanadium catalyst is approximately
It was only 19797v/v/time. Approximately 129 liters of water, including two reaction vessels, were
The operating temperature was maintained at 265 °C. The product gas stream is then analyzed and the feed gas-oxidizer blend maintained at stoichiometric values for conversion to sulfur.
H ₂ S under the specified conditions above, including the H ₂ S to O ₂ ratio.
It was determined which catalyst was active for oxidation at 129°C (265〓). However, due to the analytical difficulties associated with measuring sulfur vapor in a gas stream, and because small amounts of SO ₂ are generated concomitantly to the reaction initiation conditions that produce sulfur, the product gas is not sensitive to the presence of SO ₂ . It was analyzed. At the initial operating temperature of 129°C (265°C), no SO ₂ was detected in the product gas recovered from the reactor containing the vanadia catalyst, but no SO ₂ was detected from the reactor containing the vanadium-bismuth catalyst.
536ppmV was generated. Therefore, under the conditions of this experiment,
The onset temperature for vanadium-bismuth catalysts is approximately
The temperature is below 129℃ (265〓). For the vanadia catalyst, the increase in operating temperature ended up being 159°C (318〓).
SO ₂ exceeds 2-3 ppmV at 188℃ (370〓)
Generates 473ppmV, 609ppmV at 199℃ (390〓)
This means that it has generated . Experimental results show that the vanadium-bismuth catalyst of the present invention reacts with H ₂ S at lower temperatures than for vanadia catalysts.
The vanadium-bismuth catalyst was found to be more active than the vanadium-bismuth catalyst, which initiates the reaction to sulfur and does not initiate any reaction up to this operating temperature.
The temperature of 29℃ (53〓) was higher than the temperature of 129℃ (265〓). Based on data obtained at 129°C (265〓), 188°C (370〓) and 199°C (390〓), the vanadia catalyst has a higher operating temperature than the operating temperature for the vanadium-bismuth catalyst giving comparable products.
Required operating temperature 70℃ (105-125〓) higher. The results of the experiment showed that the experimental manipulation was rather
The superiority of vanadium-bismuth catalysts is further demonstrated when considering the fact that vanadia catalysts are more favorable. In this regard, it is noted that when more than 50% by volume of vanadia catalyst was used, the volumetric hourly space velocity for the vanadia catalyst was only 2/3 of that for the vanadium-bismuth catalyst. Also, although vanadium-bismuth catalysts are somewhat metal-rich by weight, vanadium-bismuth catalysts actually contain fewer active metal atoms due to the relatively large molecular weight of bismuth. More specifically, vanadia catalysts contain 1.80 mmol of vanadium (as metal) per gram of catalyst, whereas vanadium-bismuth catalysts contain only 1.55 mmol of vanadium per gram.
It contains only millimoles of vanadium and bismuth (as metals). Nevertheless, vanadium-bismuth catalysts were found to be significantly superior to vanadia catalysts. In particular embodiments of the invention, the invention particularly provides about 5 to
Useful for treating feed gas streams containing 40% _H2S by volume, especially when the feed gas stream has a relatively high partial pressure, e.g., about 2.0 ^psia or higher, and more typically contains water vapor at or above about 0.28 Kg/cm ² (4.0 psia), the feed gas stream is mixed with air, preferably in stoichiometric amounts, and the resulting gas mixture is combined with a significant amount of H ₂ S is passed through an adiabatic reactor containing a granular vanadium-bismuth catalyst under the conditions described above such that the sulfur is converted to elemental sulfur vapor. The product gas containing elemental sulfur is passed through a sulfur condenser or other suitable means for separating sulfur from the product gas and a purified product gas containing residual _H2S is discharged. A portion of the purified product gas is then recycled and enters the reactor containing _H2S in a predetermined range, e.g. 3-6% by volume, or below a predetermined maximum, typically and preferably 5% by volume. Mix with feed gas, such as a mixture of recycle gas, air and feed gas. The remainder of the purified product gas is treated in one of three ways. These three methods are described below (these methods are used in embodiments of the present invention in which the H ₂ S content of the recovered gas stream after treatment with the vanadium-bismuth catalyst is too high to be discharged to the atmosphere). ). (1) If the H ₂ S to SO ₂ volume ratio of the purified product gas stream is approximately 2.0, the gas stream is heated to an elevated temperature, e.g.
Under conditions of ~482 °C (400〓~900〓), it can be contacted with a porous refractory oxide-containing catalyst, e.g. alumina, and a significant amount of _H2S can be transferred to the reaction equation
(3) into elemental sulfur, which can be recovered, for example, by condensation. In this embodiment of the invention, vanadium-bismuth catalysts, such as those described above, are most preferably used to effect the conversion to sulfur, and such catalysts require lower operating temperatures and/or or under more difficult conditions of high space velocities, it is highly active and therefore useful in providing the same conversion of H ₂ S to sulfur as alumina. (2) H ₂ S to SO ₂ volume ratio in the purified product gas stream is substantially greater than or equal to _2.0 ;
If it is desired to vary the _SO2 ratio, the purified product gas stream is mixed with a sufficient amount of air;
giving a capacity ratio of H ₂ S/(SO ₂ + O ₂ ) of approximately 2.0,
The resulting gas is contacted with a vanadium-bismuth catalyst under the conditions described above to convert it to elemental sulfur. Alternatively, and less preferably, a vanadium-bismuth catalyst may be substituted with a vanadium-bismuth catalyst containing vanadium oxide or vanadium sulfide supported on a porous refractory oxide support, resulting in approximately 0.07 Kg/cm ² (1.0 psia). At the following partial pressure,
Or contact with this at an operating temperature of about 316°C (600°C) or higher to give a mixed gas water vapor. Although the use of a vanadia catalyst gives a lower activity for converting H ₂ S to sulfur than when using a vanadium-bismuth catalyst, the lower activity can be used in some cases, e.g. when the price of the catalyst is particularly important. It is appropriate for (3) of the recovered gas stream or purified product gas stream after condensing the sulfur by methods (1) and (2) above;
If the H ₂ S content is too high to be discharged into the atmosphere, and if such a gas stream is converted to SO ₂ (air pollution standards for _{SO 2 are} less stringent than for H ₂ S), ), such a gas stream is combusted to convert the H ₂ S contained therein to SO ₂ if it can be vented to the atmosphere. Combustion is carried out by heating to temperatures above about 538°C (1000°C) in the presence of excess oxygen, but in contact with the vanadium-bismuth catalyst of the invention described above, within the conversion conditions to SO ₂ described above. It is preferable to do so. The use of vanadium-bismuth catalysts has a distinct advantage over thermal combustion: the gas stream to be treated does not require much preheating, and vanadium-bismuth catalysts can be used almost always at temperatures below 260°C (500°C). _H2S
It has activity for converting into SO ₂ . The present invention is not limited to the above embodiments. For example, by changing the catalyst process of the present invention, reaction formula (1)
By easily controlling the amount of oxygen between the amount required for reaction formula (2) and the amount required for reaction equation (2), H ₂ S can be combined with a predetermined amount of sulfur.
It is also possible to oxidize to a combination of _SO2 .

Claims (1)

[Claims] 1. In oxidizing hydrogen sulfide (H ₂ S) to elemental sulfur in the gas phase, H ₂ S-containing gas is heated at 121° to 482°C in the presence of oxygen or nitric oxide (SO ₂ ). (250゜～900〓)
A method for oxidizing hydrogen sulfide, characterized in that the catalyst is brought into contact with a solid catalyst at a temperature of . 2. The method of claim 1, wherein the catalyst oxidizes _H2S to sulfur with little deactivation and the treatment is carried out over a period of at least 90 days. 3. The H ₂ S-containing gas further comprises one or more components selected from the group consisting of H ₂ , CO, NH ₃ and lower hydrocarbons, and the said component is not oxidized at all during the contact period. The method described in item 1 or 2. 4. A process according to claim 1, 2 or 3, wherein oxygen is present in the stoichiometric proportion necessary to convert _H2S to sulfur during the contacting. 5. A process according to claim 1 or 2, wherein oxygen is present in a proportion between 0.9 and 1.1 times the stoichiometric proportion required to convert _H2S to sulfur during the contacting. 6 mixing a feed gas stream containing H ₂ S with air;
In a reaction zone maintained at a temperature of 121° to 482°C (250° to 900°C), the resulting mixture is brought into contact with a catalyst in which catalytically active vanadium and bismuth components are supported on a refractory carrier, and the contact
The method according to claim 1, wherein H ₂ S reacts with oxygen supplied by air to produce elemental sulfur vapor, and a product gas containing all of the elemental sulfur produced in the reaction zone is removed from the reaction zone. . 7. The catalyst is granular and consists of a refractory oxide supporting a vanadium component and a bismuth component as main components, and the catalyst is selected from the group consisting of vanadium oxide, vanadium sulfide, bismuth oxide, bismuth sulfide, and bismuth vanadate. 7. The method of claim 6, comprising a vanadium component and a bismuth component. 8. said _H2S -containing gas is a feed gas stream containing a significant amount of _H2S ; (250°~
contact with a catalyst containing a catalytically active vanadium component and a bismuth component in a reaction zone maintained at a temperature of 900㎓), said contact converting the entire amount of H ₂ S in said admixture gas stream to elemental sulfur vapor. (c) recovering the product gas stream from step (b) above and separating elemental sulfur therefrom to obtain a purified gas stream; (d) converting a portion of the purified gas stream product ( a) recycling into the process. The method according to claim 1. 9 said feed gas stream comprises 5 to 40% by volume _H2S , said portion of said purified gas stream product recycled to step (a) increases the _H2S concentration in said admixture gas stream by 10% by volume; and sufficient to bring the _H2S concentration of the feed gas stream to a predetermined value lower than the H2S concentration of the feed gas stream.
The method described in section. 10 Initial contact in the reaction zone above at 177℃
(350〓) or less and the above to produce sulfur
At least some reaction between _H2S and oxygen is carried out at 177 °C (350
〓) The method according to claim 9 carried out below. 11 At least some sulfur vapor is present at temperatures between 121° and 316°C.
10. The method according to claim 8 or 9, wherein the process is performed at a temperature in the reaction zone maintained between 250° and 600°. 12. The method of claim 1, wherein the temperature is between 121° and 316°C (250° and 600°). 13 The above H ₂ S-containing gas is further added to 0.07Kg/cm ²
(1.0 psia) or more, while the total pressure during the above contact is 0.35-35.15 Kg/cm ² (5-500 psia).
13. The method according to claim 12. 14. The method of claim 13, wherein said treatment is carried out for at least 90 days without said catalyst losing activity for oxidizing _H2S to sulfur. 15. The method of claim 12, wherein oxygen is present during contact of the _H2S with the solid catalyst. 16 (a) H ₂ S and free oxygen at 121°~316°C (250°~
600 〓) in a reaction zone maintained at a temperature of 600㎓) with a solid catalyst comprising a carrier carrying catalytically active vanadium components and bismuth components, and (b) removing elemental sulfur from the reaction zone. The method described in Section 1. 17. The method of claim 16, wherein the oxygen is supplied in the form of air. 18. The method according to claim 16 or 17, wherein the catalyst comprises vanadium oxide or vanadium sulfide and bismuth oxide or bismuth sulfide supported on a refractory oxide carrier. 19 Initial contact in the above reaction zone at 177℃
(350〓) or below, with at least some _H2S
19. The method according to claim 16, 17 or 18, wherein elemental sulfur is produced by reacting at a temperature of 177°C (350°C) or lower. 20 The portion of the reaction zone at a temperature below 177°C (350〓) contains water vapor that contacts the catalyst at a water vapor partial pressure of above 0.14 Kg/cm ² (2.0 psia), and the total pressure is 0.35
20. The method of claim 19, wherein the weight is between 5 and 300 ^psia . 21 The H ₂ S-containing gas is a feed gas stream containing H ₂ S; (a) the H ₂ S-containing feed gas stream is admixed with air; and (b) the resulting admixture is mixed with a refractory oxide. Conditions in which H ₂ S reacts with oxygen supplied by air in a reaction zone containing a solid catalyst mainly composed of catalytically active vanadium components and bismuth components supported on a carrier to generate sulfur element vapor. The above reaction was carried out at 121°~246°C (250°~475°C).
The method according to claim 1, wherein: (c) a product gas containing elemental sulfur vapor generated in the reaction zone is removed from the reaction zone. 22. The method of claim 21, wherein the catalyst is in particulate form and contains a vanadium component and a bismuth component selected from the group consisting of vanadium oxide, vanadium sulfide, bismuth oxide, bismuth sulfide and bismuth vanadate. 23. The method of claim 21 or 22, wherein the reaction is initiated at 204°C (400°C). 24. The amount of air admixed with the feed gas is such that the admixture in step (b) contains oxygen in the primarily stoichiometric proportion necessary to convert the H ₂ S to elemental sulfur vapor. Claim 2
1, 22 or 23. 25. The method of claim 24, wherein the reaction is initiated at a temperature below 177°C (350°C). 26. The method of claim 24, wherein the reaction is initiated at a temperature of 149°C (300°C) or less. 27 (a) A feed gas stream containing one or more sulfur components selected from the group consisting of SO ₂ , COS, CS ₂ and light mercaptans is
One or more active catalyst components selected from the group consisting of nickel, cobalt, iron, tungsten and molybdenum in the presence of hydrogen and water vapor in a first reaction zone maintained at a high temperature of 649°C (300° to 1200°). (b _{) The generated gas is used as the H 2 S-containing gas, and the H 2 S -} containing gas is converted into oxygen in the second reaction zone. or 121° in the presence of an oxidizing agent consisting of sulfur dioxide (SO ₂ )
The method according to claim 1, wherein the method is brought into contact with a solid catalyst containing a vanadium component and a bismuth component at a temperature of 482°C (250°C to 900°C). 28 The oxidizing gas is oxygen supplied in the form of air, and the temperature in step (b) is 121° to 246°.
℃ (250° to 475〓), and the catalyst in step (b) consists of a refractory oxide carrier supported with a vanadium component and a bismuth component as main components, and at least some of the vanadium component is 28. The method of claim 27, wherein is vanadium oxide or vanadium sulfide, and at least some of said bismuth component is in the form of bismuth oxide or bismuth sulfide. 29 The above contact in the first reaction zone was carried out at 482°C (900°C).
29. The method according to claim 28, wherein the catalyst in step (a) contains a cobalt component and a molybdenum component. 30. The method of claim 27, wherein at least some of said elemental sulfur is produced at a temperature maintained in said reaction zone between 121° and 316°C (250° and 600°). 31 In treating a feed gas stream containing H ₂ S, (a) the feed gas stream is mixed with air, and (b) the resulting mixed gas stream is heated to a temperature between 121° and 316°C (250° and 900°C). In the first reaction zone maintained at a temperature of bismuth oxide or bismuth sulfide,
said contacting is carried out in such a way that most of the H ₂ S in the admixture gas stream is converted to elemental sulfur vapor by reaction with partial oxygen, but some H ₂ S remains; (c) from step (b) above; _A first product gas stream of
(d) producing a first purified gas stream containing at least some of the purified gas stream in a second reaction zone maintained at 121° to 482°C (250° to 900°); contact with a solid oxidation catalyst containing a refractory oxide;
( _e ) recovering a second product gas stream containing elemental sulfur from which _sulfur is converted; of a feed gas stream containing H ₂ S, characterized in that the elements are separated to produce a second purified gas stream.
How to oxidize _H2S . 32 The second product gas stream contains a small amount of H ₂ S, the second product gas stream is mixed with excess air to convert the small amount of H ₂ S to SO ₂ , and then 121° to
In a third reaction zone maintained at a temperature of 482°C (250° to 900°C), the small amount of H ₂ S is 32. The method of claim 31, wherein substantially all is converted to _SO2 . 33 The catalyst in the first and second reaction zones contains a vanadium component of 7% by weight or more calculated as V ₂ O ₅ and 8% by weight or more calculated as Bi ₂ O ₃ in a porous refractory oxide carrier. The bismuth component of air is supported as a main component, and when air is used in steps (a) and (b), a substantially stoichiometric amount of oxygen is utilized in the first reaction zone, and a substantially stoichiometric amount of oxygen is used in the first reaction zone. Claim 31, wherein SO ₂ and O ₂ are utilized in the second reaction zone and mixed to convert H ₂ S to elemental sulfur in the first and second reaction zones.
The method according to paragraph or paragraph 32. 34. The method of claim 31, wherein at least some of said elemental sulfur is produced in said reaction zone at a temperature of 121° to 316°C (250° to 600°). 35 In removing H ₂ S from a feed gas stream, (a) the feed gas stream is brought to a temperature in the presence of oxygen;
In the first reaction zone maintained at 121° to 482°C (250° to 900°), conditions are such that almost all of the above H ₂ S is converted to elemental sulfur, but the remaining H ₂ S remains. (b) The residual H ₂ S is heated at 121° to 482°C (250° to 900°).
In the _second reaction zone maintained at a _temperature of , amorphous aluminosilicate zeolite, crystalline aluminosilicate zeolite, and mixtures thereof. All of the above residual gas to be converted to SO ₂ , and this conversion
characterized in that all portions of said residual H ₂ S are converted to SO ₂ without producing SO ₃ , and (c) recovering a product gas stream free of SO ₃ but containing SO ₂ . Method of oxidizing hydrogen sulfide. 36 Contact in step (b) above at 316℃ (600〓)
At lower temperature, at least 0.105Kg/ ^cm2 (1.5psia)
36. The method of claim 35, wherein the temperature is maintained in the first reaction zone between 121 DEG and 232 DEG C. (250 DEG -450 DEG). 37 The oxygen is supplied in the form of air in the steps (a) and (b), and the air supplied in the step (a) is sufficient to convert the H ₂ S in the supply gas into elemental sulfur. 35. The catalyst in both steps (a) and (b) comprises vanadium oxide or vanadium sulfide and bismuth oxide or bismuth sulfide. Method described. 38 In oxidizing H ₂ S from a feed gas stream containing water vapor at a partial pressure of 0.07 Kg/cm ² (1.0 psia) or greater, (a) the feed gas stream is heated between 121° and 482°C (250° ~900
In the first reaction zone maintained at a temperature in the range of 〓), the solid catalyst supporting vanadium and bismuth effective catalyst components in the presence of oxygen and all parts of the H ₂ S react with the oxygen to produce elemental sulfur. (b) _The residual H ₂ S is heated to 121° to 316°C (250° to 600°).
temperature and oxygen is present and water vapor is 0.07
^A secondary
In the reaction zone, almost all of the H ₂ S is brought into contact with a catalyst supporting a vanadium component and a bismuth component as main active components to react with the oxygen to produce SO ₂ , (c) Reduced _H2S content compared to the feed gas flow above
A process for the oxidation of hydrogen sulfide, characterized in that a product gas stream containing SO ₂ is recovered. 39 Contact in step (b) above at 316℃ (600〓)
At lower temperature, at least 0.105Kg/ ^cm2 (1.5psia)
39. The method of claim 38, wherein the temperature is maintained in the first reaction zone between 121° and 232°C (250° and 450°). 40 The above oxygen is supplied in the form of air in the steps (a) and (b), and the air supplied in the step (a) is required to convert the above H ₂ S in the supply gas to elemental sulfur. and the catalyst in both steps (a) and (b) comprises vanadium oxide or vanadium sulfide and bismuth oxide or bismuth sulfide. The method according to item 39. 41 Elemental hydrogen is present in said feed gas and in steps (a) and (b) said elemental hydrogen remains completely unoxidized and is recovered together with said product gas stream. The method according to item 40. 42 Ammonia is present in the feed gas, and this ammonia remains completely unoxidized in steps (a) and (b) and is recovered together with the product gas stream. The method described in section. 43. The method of claim 40, wherein the catalyst in steps (a) and (b) remains undeactivated for at least 90 days.