KR20000008552A - Selectively oxidizing catalysis of hydrogen sulfide and method for recollecting sulfur thereby - Google Patents

Abstract

PURPOSE: A selectively oxidizing catalysis of a hydrogen sulfide is provided to maintain an activity even in case of an excessive moisture, to obtain an excellent recollecting rate of a sulfur, and to recollect the sulfur by using the catalysis. CONSTITUTION: A selectively oxidizing catalysis is formed by an oxide including vanadium and titanium. The oxide comprises: a mixed oxide of a vanadium oxide and a titanium dioxide; dipping the vanadium oxide to the titanium dioxide; a complex oxide represented as Va-Tib-Oc; and maintaining 2:98 or 95:5 for a mole ratio of the vanadium and the titanium.

Description

Catalyst for Selective Oxidation of Hydrogen Sulfide and Recovery Method of Sulfur Using It

The present invention relates to a catalyst for oxidizing hydrogen sulfide, a catalyst for oxidizing hydrogen sulfide which is a colorless toxic gas using the same, and a method for recovering sulfur using the same.

Hydrogen sulfide is a colorless, odorous gas and one of the substances that causes air pollution. Hydrogen sulfide is generated in a large amount by biological action, but as industrial facilities increase, a large amount of hydrogen sulfide is also generated in various industrial facilities, which causes more serious air pollution. Since such air pollution can reduce the degree of damage according to the structure and operation method of the discharge facility, a method for efficiently removing hydrogen sulfide emitted from the industrial facility is urgently required.

The Claus reaction has been used as a method of removing hydrogen sulfide. According to this method, hydrogen sulfide can be recovered as non-toxic sulfur through two steps, a thermal oxidation process and a catalytic reaction process.

In the thermal oxidation process, a part of hydrogen sulfide is oxidized in a high temperature furnace at 1100 to 1200 ° C. and converted to sulfur dioxide (Scheme 1).

2H ₂ S + ₃ O ₂ → 2SO ₂ + 2H ₂ 0

In the Klaus reaction process, unreacted hydrogen sulfide and sulfur dioxide obtained from Scheme 1 are controlled at a molar ratio of 2: 1, and converted to elemental sulfur by condensation in the presence of an alumina catalyst.

2H ₂ S + SO ₂ ↔ 3 / nS _n + 2H ₂ 0

However, the Klaus process has a limited recovery in yellow yield for the following reasons.

First, the Klaus reaction is thermodynamically reversible, so the equilibrium conversion is limited.

Second, it is difficult to precisely control hydrogen sulfide and sulfur dioxide in a 2: 1 molar ratio.

Third, since it is difficult to remove the water produced in the forward reaction represented by Scheme 2, as a result, the reverse reaction prevails and the efficiency of converting hydrogen sulfide to elemental sulfur is lowered.

Due to the problems described above, in the Klaus process, untreated gas is usually discharged. Incineration of such untreated gas produces more than about 1000 ppm of sulfur dioxide, which exceeds the emission standards set by the recently tightened environmental law.

In order to solve the above problems, an additional process for treating untreated sulphide (tail-gas) discharged from the Claus process has been developed. Among them, high sulfur recovery yields include MODOP (Mobil Direct Oxidation Process: EP 0078 690-A2) and Super Claus (US 5,286,697). These processes convert hydrogen sulfide to elemental sulfur using oxygen as the reactant, as shown in Scheme 3 below.

2H ₂ S + O ₂ → 2 / nS _n + 2H ₂ 0

In the Modoop process, hydrogen sulfide is reacted with oxygen in a stoichiometric ratio to convert elemental sulfur in the presence of a titanium dioxide-based catalyst, and the conversion to sulfur is higher than 90%. However, since the catalyst is poisoned by water, the water content in the reaction gas must be lowered to less than 4% by volume using a dehydration device before the reaction.

In contrast, the superclause process uses an iron-based catalyst. This iron-based catalyst is highly toxic to water, so that even in the presence of water, the yield of sulfur is 80%. In this process, however, the concentration of hydrogen sulfide must be kept as low as 1% by volume in order to achieve a smooth reaction, and oxygen must be reacted at least 10 times the equivalent ratio to limit the reverse reaction. Therefore, the total amount of gas to be treated is increased, and the oxygen must be reacted at a high equivalent ratio as described above, and thus has a disadvantage in that it is difficult to process a high concentration of hydrogen sulfide of 2 vol% or more.

In order to solve the above problem, a method of using a catalyst having improved activity under the mode of reaction (using an equivalent amount of oxygen compared to hydrogen sulfide), that is, a vanadium-based catalyst, has been proposed. According to this method, it has the advantage that the amount of oxygen relative to hydrogen sulfide can be used as an equivalent ratio, so that it is possible to process a high concentration of hydrogen sulfide. A concrete example of this method is as follows.

According to US Pat. No. 4,311,683, using an acidic gas having a hydrogen sulfide concentration of 500 ppm to 10% by volume and maintaining the pressure in the reactor at 100 psi, a yellow recovery yield of 75 to 90% was obtained at a reaction temperature of 232 ° C or lower.

According to US Pat. Nos. 4,444,742 and 4,576,814, a yellow recovery of 70-80% was obtained at 246 ° C. or less in the presence of a two-component catalyst of V ₂ O ₅ —Bi ₂ O ₃ and 3% by volume of water. Further, according to US Pat. No. 5,512,258, 2 vol% hydrogen sulfide, sulfur dioxide 1 in the presence of an A _{4 ± x} V _{2 ± y} O ₉ catalyst system (A is Mg, Ca, Zn, 0 ≦ x ≦ 0.2, 0 ≦ y ≦ 0.5) It is reported that when the gas consisting of 1% by volume of oxygen in volume% and equivalent ratio contains 30% by volume of water vapor, a conversion rate of 70-90% hydrogen sulfide can be obtained at the reaction temperature of 220 ° C. However, no selectivity to sulfur or final yield of sulfur is mentioned.

By the way, most of the catalysts reported in the above-mentioned patents are those that show activity under conditions containing little or no water, and in actual processes, there are problems in that the catalysts are difficult to use because they contain a large amount of water vapor. In order to solve this problem, the reaction was carried out in a low temperature region (245 ° C. or less), but in such a low temperature region, there is a problem in that activity decreases after a long time use of the catalyst.

The technical problem to be solved by the present invention is to provide a catalyst for the selective oxidation of hydrogen sulfide excellent in the sulfur recovery yield while the activity is not reduced even in the presence of excess moisture.

Another object of the present invention is to provide a method for recovering sulfur using the catalyst.

In order to achieve the first object, the present invention provides a catalyst for the selective oxidation of hydrogen sulfide, characterized in that the oxide containing vanadium and titanium.

The oxide is a mixed oxide of vanadium oxide and titanium dioxide or a composite oxide represented by V _a -Ti _b -O _c (0 <a <2, 0 <b <3, 0 <c <9). In particular, when the oxide is a mixed oxide of vanadium oxide and titanium dioxide, it is preferable that the vanadium oxide is supported on titanium dioxide.

The mixing molar ratio of vanadium and titanium in the catalyst of the present invention is preferably 2:98 to 95: 5, more preferably 10:90 to 90:10. Here, when the content of vanadium is larger than the above range, titanium does not properly perform the role of throttling. Titanium-containing oxides, that is, titanium dioxide, serve to inhibit the deactivation by reoxidizing the reduced vanadium during the oxidation reaction of hydrogen sulfide, which is not preferable because the activity of the catalyst is lowered.

The catalyst of the present invention may be achieved by supporting _a mixed oxide of vanadium oxide and titanium dioxide or _a complex oxide represented by Va-Yi _b -O _c on a carrier. At this time, the supported content of the compounds is preferably 3 to 30% by weight relative to the catalyst. At this time, it is preferable to use at least one selected from the group consisting of neutral silicon carbide, silicon oxide and α-alumina.

The content of each component is most preferable when satisfying the above conditions, for the following reason. The selective oxidation of hydrogen sulfide using the catalyst is because the catalyst is reduced by hydrogen sulfide to lose lattice oxygen, and then proceeds to an oxidation-reduction mechanism in which gaseous oxygen maintains activity while providing lattice oxygen to the catalyst. . In other words, the activity and the maintenance of the oxidation reaction depends on the amount of lattice oxygen contained in the catalyst, the re-oxidation of the catalyst by the gaseous oxygen, and the extent thereof. Therefore, if it is out of the above range, the amount of lattice oxygen of the catalyst decreases and the activity of the catalyst gradually decreases over time.

A second object of the present invention is a method for recovering elemental sulfur from hydrogen sulfide contained in the reaction gas by reacting a reaction gas containing hydrogen sulfide with oxygen or air under a catalyst,

It is achieved by a method for recovering sulfur, characterized in that the catalyst is made of an oxide containing vanadium and titanium.

Any component of the catalyst according to the invention can be made as long as it can be in the form of a mixed oxide or complex oxide comprising vanadium and titanium as described above. Oxides containing vanadium and titanium can be obtained from corresponding precursors or by mixing vanadium oxide and titanium dioxide in a predetermined mixing ratio. The vanadium precursor and the titanium precursor for preparing the catalyst can be used as long as they are dissolved in a solvent such as water and alcohol. Among them, NH ₄ VO ₃ , VOCl ₃ , VOSO ₄ · 3H ₂ O, vanadium alkoxide, and the like are used as precursors of vanadium, and Ti (SO ₄ ) ₂ · nH ₂ O, Ti [O (CH ₂ ) ₃ CH ₃ ] ₄ , TiCl ₃ , titanium alkoxides, and the like. Looking at the process for producing a catalyst using such a vanadium or titanium precursor as follows.

The vanadium precursor and the titanium precursor are dissolved in an aqueous oxalic acid solution. This mixture is removed by moisture using an evaporation drying method to obtain a catalyst precursor.

Alternatively, a catalyst precursor supported on a silica carrier may be prepared by adding carrier particles such as silica to an oxalic acid solution in which the vanadium precursor and the titanium precursor are dissolved, and then evaporating to dryness.

By firing the precursor obtained in the above process at 400 ~ 500 ℃ it is possible to finally obtain a catalyst.

On the other hand, the method for recovering sulfur from hydrogen sulfide using the catalyst according to the present invention will be described.

In the presence of a catalyst according to the invention a reaction gas comprising hydrogen sulfide is reacted with oxygen or air. At this time, the reaction temperature is preferably 200 to 330 ° C, particularly 220 to 280 ° C. The catalyst is deactivated when the reaction temperature is lower than 200 ° C., and when the temperature is higher than 330 ° C., the recovery of sulfur is lowered, which is not preferable.

Further, in the reaction conditions, the molar ratio of oxygen / hydrogen sulfide is 0.5 to 1.0, preferably 0.5 to 0.6 and the space velocity of the inlet gas is 3,000 to 1,000,000 L / kg-cat. hr, in particular 3,000-400,000 L / kg-cat. It is preferable that it is hr.

The content of hydrogen sulfide is 1 to 40% by volume with respect to the reaction gas, the volume of oxygen is preferably 50 to 100% by volume with respect to hydrogen sulfide.

The catalyst according to the present invention retains its activity even when 5 to 30% by volume of water vapor is added to the reaction gas.

Hereinafter, the present invention will be described with reference to the following examples, but the present invention is not necessarily limited to the following examples.

In the following examples, the conversion rate of hydrogen sulfide, the selectivity of sulfur, and the recovery rate of sulfur were calculated as follows.

H ₂ S conversion rate (%) = {([H ₂ S] _inflow- [H ₂ S] _outflow ) / [H ₂ S] _inflow } × 100

% Selectivity of sulfur = {([H ₂ S] _inflow- [H ₂ S] _outflow- [SO ₂ ] _outflow ) / ([H ₂ S] _inflow- [H ₂ S] _outflow )} × 100

Sulfur recovery rate (%) = {H ₂ S conversion rate x selectivity of sulfur} / 100

<Example 1>

2.34 g of NH ₄ VO _{3 and} 6.80 g of Ti [O (CH ₂ ) ₃ CH ₃ ] ₄ were added to 500 ml of a 5 wt% aqueous solution of oxalic acid to make a clear solution, followed by evaporation to remove moisture. Thereafter, the mixture was calcined at 450 ° C. for 5 hours in an air atmosphere to prepare a composite oxide catalyst of vanadium and titanium.

The catalyst was charged to the reactor, and then 5% by volume of hydrogen sulfide, 2.5% by volume of oxygen and a mixed gas of helium in the remainder were supplied thereto. At this time, the space velocity is 94,000ℓ / kg-cat. Fixing with hr and carrying out the oxidation reaction of hydrogen sulfide while changing the reaction temperature to 225-325 ℃ to measure the conversion rate of hydrogen sulfide, selectivity and recovery of sulfur is shown in Table 1 below.

Temperature Removal Efficiency of Hydrogen Sulfide by Composite Oxide Catalyst of Vanadium and Titanium Temperature (℃) Sulfur conversion rate (%) Sulfur selectivity (%) Yellow recovery rate (%) 225 88 99 87.1 250 93 100 93.0 275 92 100 92.0 300 90 99 89.1 325 88 98 86.2

As can be seen from Table 1, the catalyst according to Example 1 was excellent in the recovery of the sulfur in the reaction temperature range of 225-325 ℃ 86.2% or more.

<Example 2>

VOSO ₄ · 3H ₂ O 8.70g and Ti (SO ₄₎ 5 wt% nitric acid solution 400㎖ _2, was dissolved by adding 4H ₂ O 13.3g. 16 g of silica was added thereto, followed by evaporation to remove moisture.

Thereafter, calcining at 450 ° C. for 5 hours to prepare a catalyst (hereinafter, referred to as V ₂ O ₅ -TiO ₂ / SiO ₂ ) having 10 wt% of vanadium oxide and titanium oxide supported on the silica carrier.

The catalyst was charged to a reactor and then fed with 5% by volume hydrogen sulfide, 2.5% by volume oxygen and a balance of helium. At this time, the space velocity is 94,000ℓ / kg-cat. Fixed in hr and subjected to the oxidation of hydrogen sulfide while changing the reaction temperature to 225-325 ℃ to measure the conversion of hydrogen sulfide, selectivity and recovery of sulfur is shown in Table 2 below.

Removal Efficiency of Hydrogen Sulfide by Temperature by V ₂ O ₅ -TiO ₂ / SiO ₂ Catalyst Temperature (℃) Sulfur conversion rate (%) Sulfur selectivity (%) Yellow recovery rate (%) 225 89 99 88.1 250 94 100 94.0 275 93 100 93.0 300 90 99 89.1 325 88 98 86.2

From Table 2, the catalyst according to Example 2 exhibited a yellow recovery of 88.1-94.0% in the low temperature region of about 250 ° C, and 86.2-93.0% of the yellow recovery in the high temperature region of 250 ° C or higher.

<Example 3>

3.45 g of VOCl ₃ was added and dissolved in 200 ml of distilled water, and titanium dioxide was added thereto, followed by evaporation to remove water.

Thereafter, calcining at 450 ° C. for 5 hours to prepare a catalyst (hereinafter, referred to as V (10) / TiO ₂ ) in which vanadium oxide was supported on titanium dioxide at 10% by weight.

The catalyst was charged to a reactor and then fed with 5% by volume hydrogen sulfide, 2.5% by volume oxygen and a balance of helium. At this time, the space velocity is 94,000ℓ / kg-cat. Fixed in hr and subjected to the oxidation of hydrogen sulfide while changing the reaction temperature to 225-325 ℃ to measure the conversion of hydrogen sulfide, selectivity and recovery of sulfur is shown in Table 3 below.

Temperature Removal Efficiency of Hydrogen Sulfide by V (10) / TiO ₂ Catalyst Temperature (℃) Sulfur conversion rate (%) Sulfur selectivity (%) Yellow recovery rate (%) 225 89 99 88.1 250 94 100 94.0 275 93 100 93.0 300 91 99 90.1 325 88 99 87.1

From Table 3, it can be seen that the catalyst according to Example 3 exhibits a sulfur recovery yield of 87.1% or more at a reaction temperature of 225 to 325 ° C.

<Example 4-7>

Except for adding 5, 10, 20, 30% by volume of water to the mixed gas, the conversion rate of hydrogen sulfide, the selectivity of sulfur and the recovery rate were measured in the same catalyst and reaction conditions as in Example 1, Indicated.

Removal Efficiency of Hydrogen Sulfide with V ₂ O ₅ -TiO ₂ Catalyst According to Water Content Moisture content (%) division Temperature (℃) 225 250 275 300 325 Example 4 5 % Conversion 88 92 91 87 85 Selectivity (%) 99 100 100 98 96 Yellow recovery rate (%) 88.9 92 91 85.3 81.6 Example 5 10 % Conversion 88 91 89 84 80 Selectivity (%) 99 99 98 95 92 Yellow recovery rate (%) 87.1 90.1 87.2 79.8 73.6 Example 6 20 % Conversion 87 88 85 81 75 Selectivity (%) 97 97 96 91 89 Yellow recovery rate (%) 84.4 85.4 81.6 73.7 66.8 Example 7 30 % Conversion 86 85.5 83 77 67 Selectivity (%) 96 96 94 89 85 Yellow recovery rate (%) 83 82.1 78.0 68.5 57

From Table 4, it can be seen that the catalyst prepared according to Example 1 has high sulfur recovery rate and maintains catalytic activity even in the presence of excess moisture. As the water content increases, the yellow recovery yields tend to drop little by little. However, when the reaction temperature is controlled to 220 to 270 ° C., even when the water contains up to 30% by volume, the yield of about 80% is obtained.

<Example 8>

The V (10) / TiO ₂ catalyst according to Example 3 was charged to the reactor, and then a mixed gas of 5 vol% hydrogen sulfide, 2.5 vol% oxygen and the rest was helium was supplied. The reaction temperature is 250 ℃, the space velocity is 94,000ℓ / kg-cat. hr _, under the reaction conditions without adding water or 30 vol% perm, the hydrogen sulfide conversion and the sulfide yield according to the oxygen / hydrogen sulfide ratio were measured and shown in Table 5 below.

Removal Efficiency of Hydrogen Sulfide in V (10) / TiO ₂ Catalysts According to Oxygen / Hydrogen Sulfide Molar Ratios Molar ratio of oxygen / hydrogen sulfide If no water is added When 30% by volume water is added % Conversion Selectivity (%) Yellow recovery rate (%) % Conversion Selectivity (%) Yellow recovery rate (%) 0.4 90 100 90 73 99 72.3 0.5 93 100 93 85.5 96 82.1 0.6 98 92 90.1 95 85 80.8 0.8 99 86 85.1 97 70 67.9 1.0 99 80 79.2 98 60 58.8

When the molar ratio of oxygen to hydrogen sulfide was less than 0.5, the selectivity was low, whereas the conversion was low. On the other hand, if the molar ratio of oxygen to hydrogen sulfide is greater than 0.5, the opposite trend was observed. In the case where an equivalent amount of oxygen was used for hydrogen sulfide (mole ratio of oxygen / hydrogen sulfide = 0.5), an optimum sulfur recovery yield was obtained. At this time, even if the water contained 30% by volume, the reduction of the yellow recovery is about 10%.

Example 9

The oxidation reaction of hydrogen sulfide was carried out under the same reaction conditions as in Example 2, except that the reaction temperature was 250 ° C. and the molar ratio of oxygen / hydrogen sulfide was fixed at 0.5. Hydrogen sulfide conversion and sulfur recovery were measured while changing the concentration of hydrogen sulfide, and are shown in Table 6 below.

Hydrogen Sulfide Removal Efficiency with Hydrogen Sulfide Concentration in [V ₂ O ₅ -TiO ₂ ] / SiO ₂ Catalysts Hydrogen sulfide concentration (% by volume) % Conversion Selectivity (%) % Recovery 5 93 100 93 10 94 100 94 20 96 99 93.1 40 97 98 95.1

From Table 6, it can be seen that using a catalyst containing vanadium and titanium, the sulfur recovery yield is excellent regardless of the concentration of hydrogen sulfide.

<Example 10-12>

Hydrogen sulfide oxidation was carried out under the same conditions as in Example 1-3 except that 30 vol% of water was contained at the reaction temperature of 240 ° C.

Under the same conditions as in Example 1-3, hydrogen sulfide conversion and sulfur recovery rate according to reaction time were measured and shown in Table 7 below.

Example 13

A catalyst in which vanadium oxide was supported on titanium dioxide (hereinafter referred to as V (50) / TiO ₂ ) according to the same method as in Example 12, except that the content of vanadium oxide was 50% by weight instead of 10% by weight. Prepared.

Under the same conditions as in Example 1-3, hydrogen sulfide conversion and sulfur recovery rate according to reaction time were measured and shown in Table 7 below.

Comparative Example 1

A catalyst in which vanadium oxide was supported on silica was prepared according to the same method as in Example 12, except that the content of vanadium oxide was 30% by weight instead of 10% by weight (hereinafter, referred to as V (30) / SiO ₂ ). It was.

Under the same conditions as in Example 1-3, hydrogen sulfide conversion and sulfur recovery rate according to reaction time were measured and shown in Table 7 below.

Comparative Example 2

Carrier-free vanadium oxide (Aldrich) was used as a catalyst.

Under the same conditions as in Example 1-3, hydrogen sulfide conversion and sulfur recovery rate according to reaction time were measured and shown in Table 7 below.

Comparative Example 3

1.17 g of NH ₄ VO ₃ and 3.50 g of Bi ₂ (NO) ₃ .5H ₂ 0 were added and dissolved in 250 ml of a 5% by weight aqueous solution of oxalic acid, and then water was removed by evaporation to dryness.

Thereafter, the mixture was calcined at 450 ° C. for 5 hours to prepare a mixed oxide of vanadium and bismuth (hereinafter referred to as V ₂ O ₅ —Bi ₂ O ₃ ).

Hydrogen sulfide conversion and sulfur recovery over time under the same conditions as in Example 1-3 were measured and shown in Table 7 below.

Removal efficiency of hydrogen sulfide by reaction time for various catalysts Response time (hr) 5 10 20 30 40 50 60 70 80 Example 10 V-Ti composite oxide % Conversion 87 87 87 87 87 86 87 87 86 Selectivity (%) 97 97 97 97 97 97 96 97 96 Yellow recovery rate (%) 84.4 84.4 84.4 84.4 84.4 83.4 83.5 84.4 82.6 Example 11 V ₂ O ₅ -TiO ₂ / SiO ₂ % Conversion 86 86 86 86 86 85 86 86 85 Selectivity (%) 97 97 97 96 97 97 97 97 97 Yellow recovery rate (%) 83.4 83.4 83.4 82.6 83.4 82.5 83.4 83.4 82.5 Example 12 V (10) / TiO ₂ % Conversion 87 86 86 86 86 85 85 85 85 Selectivity (%) 97 97 97 97 96 97 97 98 98 Yellow recovery rate (%) 84.4 83.4 83.4 82.5 82.6 82.5 82.5 83.3 83.3 Example 13 V (50) / TiO ₂ % Conversion 85 85 84 85 84 81 80 79 78 Selectivity (%) 96 96 96 95 95 95 95 94 93 Yellow recovery rate (%) 81.6 81.6 80.6 80.8 79.8 77.0 76 74.3 72.5 Comparative Example 1 V (30) / SiO ₂ % Conversion 85 85 82 70 58 53 46 32 14 Selectivity (%) 98 99 98 98 98 98 99 99 100 Yellow recovery rate (%) 83.3 84.2 80.4 67.9 56.8 51.9 45.5 31.7 14 Comparative Example 2 Bulk V ₂ O ₅ % Conversion 92 90 89 87 77 62 45 32 14 Selectivity (%) 97 96 97 97 97 97 98 98 100 Yellow recovery rate (%) 89.2 86.4 86.3 84.4 74.7 60.1 44.1 31.4 14 Comparative Example 3 V ₂ O ₅ -Bi ₂ O ₃ % Conversion 34 25 18 - - - - - - Selectivity (%) 97 99 100 - - - - - - Yellow recovery rate (%) 33 24.8 18 - - - - - -

From Table 7, the catalysts according to Comparative Examples 1-3, that is, V (30) / SiO ₂ , bulk V ₂ O ₅ or V ₂ O ₅ -Bi ₂ O ₃ , the activity decreases as the reaction time elapses. Although it can be seen that, the mixed oxide catalysts composed of vanadium and titanium according to Example 10-14 did not decrease the catalyst activity even after the reaction time at 240 ℃.

As described above, the catalyst according to the present invention can recover elemental sulfur from hydrogen sulfide gas in a relatively high temperature (200 to 330 ° C.) in a high yield. It also has the advantage that the activity of the catalyst is maintained even in the presence of excess water in the reaction gas.

Claims (20)

A catalyst for selective oxidation of hydrogen sulfide, characterized in that the oxide comprises vanadium and titanium. The catalyst for selective oxidation of hydrogen sulfide according to claim 1, wherein the oxide is a mixed oxide of vanadium oxide and titanium dioxide. The catalyst for selective oxidation of hydrogen sulfide according to claim 2, wherein vanadium oxide is supported on titanium dioxide. 2. The selective oxidation of hydrogen sulfide according to claim 1, wherein the oxide is _a complex oxide represented by V _a -Ti _b -O _c (0 <a <2, 0 <b <3, 0 <c <9). Catalyst. The catalyst for selective oxidation of hydrogen sulfide according to claim 2 or 4, wherein the molar ratio of vanadium and titanium in the oxide is 2:98 to 95: 5. The catalyst for selective oxidation of hydrogen sulfide according to claim 2 or 4, which is supported on a neutral porous carrier. The catalyst for selective oxidation of hydrogen sulfide according to claim 6, wherein the supported amount of the oxide is 3% by weight to 30% by weight relative to the catalyst. The catalyst for selective oxidation of hydrogen sulfide according to claim 6, wherein the carrier is at least one selected from the group consisting of silicon carbide, silicon dioxide and α-alumina. In the method of recovering elemental sulfur from the hydrogen sulfide contained in the reaction gas by reacting a reaction gas containing hydrogen sulfide with oxygen or air under a catalyst, The catalyst is a recovery method of sulfur, characterized in that the oxide containing vanadium and titanium. 10. The method of claim 9, wherein the oxide is a mixed oxide of vanadium oxide and titanium dioxide. The method according to claim 10, wherein vanadium oxide is supported on titanium dioxide. The method according to claim 9, wherein the oxide is _a complex oxide represented by V _a -Ti _b -O _c (0 <a <2, 0 <b <3, 0 <c <9). The method of claim 10 or 12, wherein in the oxide, the molar ratio of vanadium and titanium is from 2:98 to 95: 5. The method according to claim 10 or 12, wherein the oxide is supported on a neutral porous carrier. The method of claim 14, wherein the supported amount of the oxide is 3% to 30% by weight relative to the catalyst. 15. The method of claim 14, wherein the carrier is at least one selected from the group consisting of silicon carbide, silicon dioxide and α-alumina. The method of claim 9, wherein the content of hydrogen sulfide is 1 to 40% by volume based on the reaction gas. 10. The method of claim 9, wherein 50% by volume or less of water is added to the reaction gas. The method of claim 9, wherein the volume of oxygen is 50 to 100% by volume relative to hydrogen sulfide. The method of claim 9, wherein the space velocity of the reaction is 3,000 to 1,000,000 L / kg-cat. hr, and the reaction temperature is 200 to 330 ° C.