Sulfur dioxide selective hydrogenation catalyst and preparation method thereof

Abstract

The present invention discloses a sulfur dioxide selective hydrogenation sulfur production catalyst, which comprises a catalyst carrier and a catalyst active component, the catalyst carrier comprises 65-95% by mass of Al2O3 or a mixture of Al2O3 and SiO2, and Al2O3 exists in the form of delta-Al2O3 and / or theta-Al2O3; the catalyst comprises the following active components in percentage by mass: 1-10% of one or more elements selected from the VIIIB family in the periodic table of elements, and 5-25% of one or more elements selected from the VIB family in the periodic table of elements. The invention also discloses a preparation method and application of the catalyst. After the catalyst is adopted, the Claus tail gas purification efficiency is remarkably improved, the flue gas SO2 emission level of the device can be greatly reduced, the total sulfur recovery rate of the device can reach 99.9% and is equivalent to the Claus + Scot process level, and meanwhile the investment and operation cost of the sulfur recovery device can be greatly reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of sulfur recovery, and particularly relates to a sulfur dioxide selective hydrogenation catalyst for the Super Claus process and a preparation method thereof. Background Art

[0002] At present, most domestic refinery and coal chemical acid gas treatment plants adopt the Claus+Scot process, and the sulfur recovery rate of the whole set of devices can reach 99.9%. Compared with the Claus+Scot process, the Super Claus process has the advantages of low investment and low energy consumption, and has been widely used in coal chemical plants with small acid gas volume and low concentration. However, the total sulfur recovery rate of this process device can only reach 99.0%, and can only reach 99.5% by adding a first-stage Claus reactor (Ultra Super Claus process).

[0003] In the Super Claus process, a hydrogenation catalyst is filled at the bottom of the last-stage Claus reactor to hydrogenate and reduce SO2 in the Claus tail gas to sulfur (partially deeply reduced to H2S). The reduced tail gas then enters the oxidation reactor at the end of the process, and sulfur is directly produced by oxidizing H2S to further purify the sulfur-containing component H2S in the Claus tail gas. The prior art (CN110548517A) discloses a sulfur dioxide selective hydrogenation to sulfur catalyst. Part of this catalyst is filled in the last-stage Claus reactor. The inlet temperature of the reactor is 190-195°C, the bed temperature is 200-210°C, and the gas hourly space velocity is 8000-10000 -1 , the hydrogenation conversion rate of sulfur dioxide reaches 93% and above, and the selectivity of hydrogenating sulfur dioxide to elemental sulfur reaches 90% and above. According to the performance of this catalyst, the sulfur recovery rate of SO2 in the Claus tail gas in the hydrogenation catalyst bed is about 84%. The unreacted SO2 will directly enter the flue gas for emission, and the deeply reduced H2S will increase the treatment load of the oxidation reactor at the end of the process.

[0004] The Super Claus process has the advantages of low investment and low energy consumption in the process of treating refinery or coal chemical acid gas. However, the purification efficiency of the Claus tail gas restricts the reduction of the SO2 concentration in the flue gas emitted by the whole set of devices. In the Super Claus process, sulfur in the Claus tail gas is recovered through the process of sulfur dioxide selective hydrogenation to sulfur (at the bottom of the last-stage Claus reactor)-H2S direct oxidation to sulfur (end oxidation reactor), which plays a role in deep purification of the tail gas. Among them, there is still a large room for improvement in the sulfur recovery rate of the sulfur dioxide selective hydrogenation to sulfur part. At the same time, the improvement of the efficiency of the sulfur dioxide selective hydrogenation to sulfur stage will also reduce the inlet H2S concentration in the H2S direct oxidation to sulfur stage, which is beneficial to the control of the bed temperature of the oxidation reactor and the improvement of sulfur selectivity, thereby improving the tail gas purification efficiency of the whole set of devices. Summary of the Invention

[0005] The object of the present invention is to provide a highly active and highly selective sulfur production catalyst for selective hydrogenation of SO2 and a preparation method thereof, which are used to improve the tail gas purification efficiency of the sulfur recovery unit in the Super Claus process.

[0006] To achieve the above object, the present invention proposes the following technical solutions:

[0007] A sulfur production catalyst for selective hydrogenation of sulfur dioxide used in the Super Claus process, comprising a catalyst carrier and a catalyst active component. The catalyst carrier is Al2O3 or a mixture of Al2O3 and SiO2 with a mass fraction of 5-95%. The composition of the catalyst active component includes one or more elements selected from Group VIIIB of the periodic table with a mass fraction of 1-10%, and one or more elements selected from Group VIB of the periodic table with a mass fraction of 5-25%. The specific surface area of the catalyst of the present invention is 100-300 m² / g, the pore volume is 0.5-1.5 ml / g, and the average pore diameter is 10-100 nm.

[0008] Among them, the Al2O3 component in the carrier exists in the form of δ-Al2O3 or θ-Al2O3. During the heating and dehydration process of hydrated alumina (or aluminum hydroxide), two OH coordinated with Al 3+ One provides OH - One provides H + React to form water, detach from the coordination position of Al 3+ And form a "point defect" at the coordination position of Al 3+ Due to the existence of a large number of the above lattice defects, γ-Al2O3 has good Claus activity. During the transformation of γ-Al2O3 to high-temperature crystal forms (δ-Al2O3, θ-Al2O3, α-Al2O3), the bulk diffusion and rearrangement of aluminum and oxygen atoms occur violently, and the number of the above lattice defects decreases significantly until α-Al2O3 basically disappears. Therefore, the Claus activity of δ-Al2O3, θ-Al2O3, and α-Al2O3 is relatively low. The pore channels of α-Al2O3 are severely sintered and the specific surface area is small, which is not suitable as a catalyst carrier. The Claus activity of δ-Al2O3 and θ-Al2O3 is relatively low, and at the same time, they have a developed pore structure and a relatively high specific surface area, and can be used as catalyst carrier components. In the last-stage Claus reactor of the Super Claus process, the Claus reaction Has reached chemical reaction equilibrium, and the hydrogenation of sulfur dioxide (SO2 + H2 → 2H2O + 1 / nS n)During the process, the increase of sulfur and the decrease of sulfur dioxide in the atmosphere will promote the reverse Claus reaction, thus restricting the hydrogenation reaction of sulfur dioxide. The reduction of the Claus activity of the carrier can effectively reduce the rate of the reverse Claus reaction, thereby promoting the improvement of the conversion rate and selectivity in the sulfur dioxide hydrogenation reaction process, and further promoting the improvement of the sulfur recovery rate in the reaction process.

[0009] The specific surface area of the catalyst is 100 - 300 m² / g, the pore volume is 0.5 - 1.5 ml / g, and the average pore diameter is 10 - 100 nm. Further, it is preferably a specific surface area of 100 - 200 m² / g, a pore volume of 0.5 - 1.0 ml / g, and an average pore diameter of 20 - 50 nm. Under the operating conditions of the Super Claus process, the elemental sulfur generated by the hydrogenation reaction of sulfur dioxide exists in the polymeric form of S6 - S8. Within the above pore diameter range, the sulfur generated by the hydrogenation reaction of sulfur dioxide can quickly diffuse out of the catalyst pores, reducing the residence time in the pores. At the same time, within the above specific surface area range, the hydrogenation activity of the catalyst is appropriately inhibited, while ensuring the hydrogenation activity of SO2, reducing its hydrogenation activity towards sulfur. Under the conditions of a shorter residence time and a lower hydrogenation reaction rate, the generated sulfur can be smoothly removed, and the catalyst can have both good SO2 hydrogenation activity and higher sulfur selectivity. At the same time, within the above pore volume range, the "sulfur capacity" of the catalyst is relatively high, enhancing the activity stability of the catalyst in a low-temperature operating environment.

[0010] The present invention also provides a preparation method of the catalyst. The catalyst is prepared by an impregnation method, and the preparation process is as follows:

[0011] Step 1: Prepare a catalyst precursor. Using oxides or their hydrated oxide precursors of Al and / or Si elements as raw materials, adding a binder and a lubricant, and obtaining a catalyst carrier through kneading, shaping, drying, and calcination.

[0012] Among them, the oxide or its hydrated oxide precursor containing Al element includes aluminum hydroxide xerogel and pseudo-boehmite, and the oxide containing Si element is silica. The specific surface area of the aluminum hydroxide xerogel or pseudo-boehmite raw material is 200 - 500 m² / g, and the pore volume is 0.3 - 1.5 ml / g. The specific surface area of the silica is 50 - 300 m² / g. Further, it is preferred that the specific surface area of the aluminum hydroxide xerogel or pseudo-boehmite raw material is 300 - 500 m² / g, the pore volume is 0.5 - 1.5 ml / g, and the specific surface area of the silica is 100 - 200 m² / g. Within this parameter range, after the alumina component in the raw material is transformed into the δ-Al₂O₃ or θ-Al₂O₃ crystal form, it can still maintain an appropriate specific surface area and a large pore volume; the silica component can contribute an appropriate specific surface area and a large pore diameter. The specific surface area, pore volume, and average pore diameter of the catalyst can be maintained within the ranges of 100 - 300 m² / g, 0.5 - 1.5 ml / g, and 10 - 100 nm respectively, especially in the ranges of 100 - 200 m² / g, 0.5 - 1.0 ml / g, and 20 - 50 nm.

[0013] The drying temperature of the catalyst support is 80 - 150 °C, the calcination temperature is 700 - 1000 °C, and the calcination time is 2 - 8 h. Further, it is preferred that the calcination temperature is 800 - 900 °C and the calcination time is 3 - 5 h. γ-Al₂O₃ starts to undergo lattice rearrangement at 700 °C and transforms into the high-temperature crystal form of δ-Al₂O₃ or θ-Al₂O₃, and gradually becomes the stable α-Al₂O₃ form above 1000 °C. Under the calcination conditions of 800 - 900 °C and 3 - 5 h, the Al₂O₃ component can be transformed into a better δ-Al₂O₃ or θ-Al₂O₃ form. During this process, the pore size of the support increases, the specific surface area of the catalyst drops below 200 m² / g, and the pore diameter increases to more than 20 nm.

[0014] Step 2: Prepare an impregnating solution. Using the oxide or salt precursor containing the catalyst active component as the raw material, and adding an acidic complexing agent or a basic complexing agent at the same time, an impregnating solution is prepared.

[0015] Among them, the catalyst active component includes at least one of Fe, Co, or Ni selected from Group VIIIB elements of the periodic table, exists in the form of an oxide or a sulfide, and the content is 1 - 10%. Further, it is preferred to use oxides or sulfides of Co and Ni, and the content is 2 - 5%.

[0016] The catalyst active component also includes at least one element selected from Cr, Mo, or W in Group VIB of the periodic table, which exists in the form of an oxide or sulfide, and the content is 5-25%. Further, oxides or sulfides of Mo and W are preferred, and the content is 10-20%. Within the range of the above active component content, the catalyst has a sufficient number of active centers to ensure its sulfur dioxide hydrogenation activity; in addition, the catalyst can maintain a relatively large pore size of the carrier, which is conducive to the diffusion of sulfur in the catalyst pores and improves the selectivity of the sulfur dioxide hydrogenation reaction.

[0017] Further, the salt precursors of the Co element include cobalt nitrate, cobalt oxalate, cobalt acetate, and basic cobalt carbonate, the salt precursors of the Ni element include nickel nitrate, nickel oxalate, nickel acetate, and basic nickel carbonate, the oxides or their salt precursors of the Mo element include molybdenum trioxide and ammonium molybdate, and the oxides or their salt precursors of the W element include tungsten trioxide, ammonium tungstate, and phosphotungstic acid.

[0018] Using the salt precursors of Co and Ni and the oxides or their salt precursors of Mo and W as raw materials, an impregnation solution is prepared, and at the same time, an acid or basic complexing agent is added to promote the dissolution of the above raw materials and the dispersion of the metal components on the surface of the carrier.

[0019] The binders are organic acids such as acetic acid, citric acid, and oxalic acid, and sodium silicate and water glass, the lubricants are graphite, stearic acid, sesbania powder, starch, and paraffin, and the acid and base complexing agents include organic amines such as citric acid, phosphoric acid, ammonia water, ethylenediamine, and ethanolamine.

[0020] Step 3: Prepare the catalyst. According to the method of equal-volume or excess impregnation, the catalyst carrier obtained in Step 1 is impregnated with the impregnation solution obtained in Step 1, and then the catalyst is obtained after drying and calcination.

[0021] Among them, the drying temperature of the catalyst is 80-150°C, the calcination temperature is 200-600°C, and the calcination time is 2-8 h. Further, a calcination temperature of 300-500°C and a calcination time of 3-5 h are preferred. Under these calcination temperature and time conditions, the active components of the catalyst can be converted into a stable active form while maintaining good dispersion, thereby ensuring the activity and performance stability during use.

[0022] After preparing the catalyst, a part of the catalyst is loaded into the last-stage Claus reactor of the Super Claus process sulfur recovery unit, and under the conditions of an operating temperature of 180-220°C and a gas hourly space velocity of 1000-8000 h -1 The SO2 hydrogenation conversion rate > 95%, the selectivity of sulfur production > 98%, and the purification efficiency of the Claus tail gas is significantly improved, thereby greatly reducing the flue gas SO2 emission level.

[0023] The present invention discloses a catalyst using Al2O3 or a mixture of Al2O3 and SiO2 as a carrier, wherein Al2O3 exists in the form of δ-Al2O3 or θ-Al2O3, and at the same time has a specific surface area of 100-300 m² / g, a pore volume of 0.5-1.5 ml / g, and an average pore diameter of 10-100 nm. By controlling the crystal form of Al2O3 in the carrier components, the influence of the reverse reaction of the Claus reaction is reduced, and the conversion rate and selectivity of the sulfur dioxide hydrogenation reaction process are promoted. At the same time, within the range of the specific surface area and pore diameter of the catalyst, it can not only ensure the hydrogenation activity of SO2, but also reduce the hydrogenation reaction rate of sulfur, and has both good SO2 hydrogenation activity and sulfur selectivity. The larger pore volume improves the "sulfur capacity" of the catalyst, and the activity stability of the catalyst under low-temperature operating conditions is enhanced. Partially filling this catalyst in the last-stage Claus reactor of the Super Claus process sulfur recovery unit, at an operating temperature of 180-220 °C and a space velocity of 1000-8000 h -1 Under the conditions, the hydrogenation conversion rate of SO2 > 95%, the selectivity of sulfur production > 98%, and the purification efficiency of the Claus tail gas is significantly improved, and the SO2 emission level of the device flue gas can be greatly reduced. Under these process conditions, the total sulfur recovery rate of the device can reach 99.9%, which is equivalent to the Claus + Scot process level, and at the same time, the investment and operating costs of the sulfur recovery unit can be greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a process flow diagram of the Super Claus process to which the catalyst of the present invention is applicable.

[0025] Among them, 1 - sulfur-making furnace, 2 - first-stage sulfur cooler, 3 - first-stage heater, 4 - first-stage Claus converter, 5 - second-stage sulfur cooler, 6 - second-stage heater, 7 - second-stage Claus converter, 8 - third-stage sulfur cooler, 9 - third-stage heater, 10 - third-stage Claus converter, 11 - fourth-stage sulfur cooler, 12 - fourth-stage heater, 13 - oxidation reactor, 14 - fifth-stage sulfur cooler, 15 - liquid sulfur pool, 16 - tail gas incinerator, 17 - chimney. DETAILED DESCRIPTION OF THE INVENTION

[0026] Example 1:

[0027] (1) 15 kg of sodium metaaluminate-aluminum sulfate dry gel (specific surface area 400 m² / g, pore volume 1.0 ml / g), 3 kg of sesbania powder, 2 kg of acetic acid, and 12 kg of purified water were added to a roller kneader and kneaded for 45 minutes, then transferred to a screw extruder for forming. The formed carrier was dried at 120 °C for 4 h in a dryer and then calcined at 900 °C for 4 h in a mesh belt kiln to obtain the catalyst carrier.

[0028] (2) 1.0 kg of cobalt acetate (molecular formula: Co(CH3COO)2·4H2O), ammonium heptamolybdate (molecular formula (NH4)6Mo7O24 .4H2O) 1.5 kg, 0.8 kg of citric acid, and 8 kg of purified water to prepare an impregnation solution. The solution preparation process is carried out in a reaction kettle.

[0029] (3) Using the equal-volume impregnation method, add the solution prepared in step (2) to the carrier obtained in step (1). The impregnation process is carried out in a sugar coating machine. During the impregnation process, maintain a certain rotation speed of the sugar coating machine to ensure sufficient contact between the solution and the carrier. After the solution is completely absorbed, continue to stand for 2 h to allow the solute ions to fully diffuse into the pores of the carrier. After impregnation, the catalyst is dried at 120 °C for 3 h in a dryer and then transferred to a rotary kiln for calcination at 500 °C for 4 h to obtain the finished catalyst A-1. The metal content of A-1 is CoO 2.5%, MoO3 10%, specific surface area 150 m² / g, pore volume 0.7 ml / g, and average pore diameter 30 nm.

[0030] Example 2:

[0031] (1) 15 kg of pseudo-boehmite (specific surface area 360 m² / g, pore volume 0.8 ml / g), 3 kg of sesbania powder, 3 kg of citric acid, and 4.5 kg of purified water are added to a roller kneader and kneaded for 45 minutes, then transferred to a screw extruder for shaping. The shaped carrier is dried at 120 °C for 4 h in a dryer and then transferred to a mesh belt kiln for calcination at 800 °C for 4 h to obtain the catalyst carrier.

[0032] (2) 1.0 kg of cobalt acetate (molecular formula: Co(CH3COO)2.4H2O), ammonium heptamolybdate (molecular formula (NH4)6Mo7O 24 .4H2O) 1.5 kg, 0.8 kg of citric acid, and 7 kg of purified water to prepare an impregnation solution. The solution preparation process is carried out in a reaction kettle.

[0033] (3) Using the equal-volume impregnation method, add the solution prepared in step (2) to the carrier obtained in step (1). The impregnation process is carried out in a sugar coating machine. During the impregnation process, maintain a certain rotation speed of the sugar coating machine to ensure sufficient contact between the solution and the carrier. After the solution is completely absorbed, continue to stand for 2 h to allow the solute ions to fully diffuse into the pores of the carrier. After impregnation, the catalyst is dried at 120 °C for 3 h in a dryer and then transferred to a rotary kiln for calcination at 500 °C for 4 h to obtain the finished catalyst A-2. The metal content of A-2 is CoO 2.5%, MoO3 10%, specific surface area 140 m² / g, pore volume 0.5 ml / g, and average pore diameter 20 nm.

[0034] Example 3:

[0035] (1) 10 kg of sodium metaaluminate-aluminum sulfate dry gel (specific surface area 400 m² / g, pore volume 1.0 ml / g), 3 kg of white carbon black (specific surface area 100 m² / g), 3 kg of sesbania powder, 2.5 kg of citric acid, and 10 kg of purified water were added to a roller kneader and kneaded for 45 minutes, then transferred to a screw extruder for forming. The formed carrier was dried at 120 °C for 4 h in a dryer and then calcined at 800 °C for 4 h in a mesh belt kiln to obtain the catalyst carrier.

[0036] (2) 1.0 kg of cobalt acetate (molecular formula: Co(CH₃COO)₂·4H₂O), 1.5 kg of ammonium heptamolybdate (molecular formula (NH₄)₆Mo₇O 24 ·4H₂O), 0.8 kg of citric acid, and 9 kg of purified water were used to prepare the impregnation solution, and the solution preparation process was carried out in a reaction kettle.

[0037] (3) Using the equal-volume impregnation method, the solution prepared in step two was added to the carrier obtained in step one. The impregnation process was carried out in a sugar coating machine. During the impregnation process, the sugar coating machine was maintained at a certain rotation speed to ensure sufficient contact between the solution and the carrier. After the solution was completely absorbed, it was allowed to stand for another 2 h to enable the solute ions to fully diffuse into the internal pores of the carrier. The impregnated catalyst was dried at 120 °C for 3 h in a dryer and then calcined at 500 °C for 4 h in a rotary kiln to obtain the finished catalyst A-3. The metal content of A-3 is CoO 2.5%, MoO₃ 10%, specific surface area 160 m² / g, pore volume 0.8 ml / g, and average pore diameter 35 nm.

[0038] Example 4:

[0039] (1) 10 kg of pseudo-boehmite (specific surface area 360 m² / g, pore volume 0.8 ml / g), 3 kg of white carbon black (specific surface area 150 m² / g), 3 kg of sesbania powder, 2 kg of citric acid, and 6 kg of purified water were added to a roller kneader and kneaded for 45 minutes, then transferred to a screw extruder for forming. The formed carrier was dried at 120 °C for 4 h in a dryer and then calcined at 800 °C for 4 h in a mesh belt kiln to obtain the catalyst carrier.

[0040] (2) 1.0 kg of cobalt acetate (molecular formula: Co(CH₃COO)₂·4H₂O), 1.5 kg of ammonium heptamolybdate (molecular formula (NH₄)₆Mo₇O 24 ·4H₂O), 0.8 kg of citric acid, and 8 kg of purified water were used to prepare the impregnation solution, and the solution preparation process was carried out in a reaction kettle.

[0041] (3) Using the equal-volume impregnation method, add the solution prepared in step (2) to the carrier obtained in step (1). The impregnation process is carried out in a sugar coating machine. During the impregnation process, maintain a certain rotation speed of the sugar coating machine to ensure sufficient contact between the solution and the carrier. After the solution is completely absorbed, continue to stand for 2 h to allow the solute ions to fully diffuse into the internal pores of the carrier. After impregnation, the catalyst is dried at 120 °C for 3 h in a dryer and then transferred to a rotary kiln for calcination at 500 °C for 4 h to obtain the finished catalyst A-4. The metal content of A-4 is CoO 2.5% and MoO3 10%, the specific surface area is 140 m² / g, the pore volume is 0.7 ml / g, and the average pore diameter is 30 nm.

[0042] Example 5:

[0043] (1) 10 kg of sodium aluminate-aluminum sulfate dry gel (specific surface area 400 m² / g, pore volume 1.0 ml / g), 3 kg of white carbon black (specific surface area 100 m² / g), 3 kg of sesbania powder, 2.5 kg of citric acid, and 10 kg of purified water are added to a roller kneader and kneaded for 45 minutes, then transferred to a screw extruder for shaping. The shaped carrier is dried at 120 °C for 4 h in a dryer and then transferred to a mesh belt kiln for calcination at 800 °C for 4 h to obtain the catalyst carrier.

[0044] (2) 1.1 kg of basic cobalt carbonate (molecular formula [2CoCO3·3Co(OH)2·H2O]), 2.8 kg of ammonium tetramolybdate (molecular formula (NH4)2Mo4O 13 .2H2O), 6 kg of ammonia water (25%), and 2 kg of purified water are used to prepare the impregnation solution. The solution preparation process is carried out in a closed reaction kettle and heated to 40 - 60 °C to promote dissolution.

[0045] (3) Using the equal-volume impregnation method, add the solution prepared in step (2) to the carrier obtained in step (1). The impregnation process is carried out in a sugar coating machine. During the impregnation process, maintain a certain rotation speed of the sugar coating machine to ensure sufficient contact between the solution and the carrier. After the solution is completely absorbed, continue to stand for 2 h to allow the solute ions to fully diffuse into the internal pores of the carrier. After impregnation, the catalyst is dried at 120 °C for 3 h in a dryer and then transferred to a rotary kiln for calcination at 400 °C for 4 h to obtain the finished catalyst B-1. The metal content of B-1 is CoO 5% and MoO3 20%, the specific surface area is 100 m² / g, the pore volume is 0.6 ml / g, and the average pore diameter is 30 nm.

[0046] Example 6:

[0047] (1) 10 kg of sodium aluminate-aluminum sulfate dry gel (specific surface area 400 m² / g, pore volume 1.0 ml / g), 3 kg of white carbon black (specific surface area 100 m² / g), 3 kg of sesbania powder, 2.5 kg of citric acid, and 10 kg of purified water are added to a roller kneader and kneaded for 45 minutes, then transferred to a screw extruder for shaping. The shaped carrier is dried at 120 °C for 4 h in a dryer and then transferred to a mesh belt kiln for calcination at 800 °C for 4 h to obtain the catalyst carrier.

[0048] (2) 1.0 kg of nickel acetate (molecular formula: Ni(CH₃COO)₂·4H₂O), 1.5 kg of ammonium metatungstate (molecular formula: (NH₄)₆H₂W 12 O 40 ·xH₂O), 0.8 kg of citric acid, and 9 kg of purified water are used to prepare an impregnation solution. The solution preparation process is carried out in a reaction kettle.

[0049] (3) Using the equal - volume impregnation method, the solution prepared in step (2) is added to the carrier obtained in step (1). The impregnation process is carried out in a sugar - coating machine. During the impregnation process, a certain rotation speed of the sugar - coating machine is maintained to ensure sufficient contact between the solution and the carrier. After the solution is completely absorbed, it is left standing for 2 h to allow the solute ions to fully diffuse into the interior of the carrier pores. After impregnation, the catalyst is dried at 120 °C for 3 h in a dryer and then transferred to a rotary kiln for calcination at 500 °C for 4 h to obtain the finished catalyst C - 1. The metal content of C - 1 is NiO 2.5%, WO₃ 10%, specific surface area 160 m² / g, pore volume 0.8 ml / g, and average pore diameter 35 nm.

[0050] Example 7:

[0051] (1) 10 kg of sodium aluminate - aluminum sulfate dry gel (specific surface area 400 m² / g, pore volume 1.0 ml / g), 3 kg of white carbon black (specific surface area 100 m² / g), 3 kg of sesbania powder, 2.5 kg of citric acid, and 10 kg of purified water are added to a roller kneader and kneaded for 45 minutes, then transferred to a screw extrusion machine for shaping. The shaped carrier is dried at 120 °C for 4 h in a dryer and then transferred to a mesh - belt kiln for calcination at 800 °C for 4 h to obtain the catalyst carrier.

[0052] (2) 1.0 kg of nickel acetate (molecular formula: Ni(CH₃COO)₂·4H₂O), 1.5 kg of ammonium heptamolybdate (molecular formula: (NH₄)₆Mo₇O 24 .4H₂O), 0.8 kg of citric acid, and 9 kg of purified water are used to prepare an impregnation solution. The solution preparation process is carried out in a reaction kettle.

[0053] (3) Using the equal - volume impregnation method, the solution prepared in step (2) is added to the carrier obtained in step (1). The impregnation process is carried out in a sugar - coating machine. During the impregnation process, the sugar - coating machine maintains a certain rotation speed to ensure sufficient contact between the solution and the carrier. After the solution is completely absorbed, it is left standing for 2 h to allow the solute ions to fully diffuse into the interior of the carrier pores. After impregnation, the catalyst is dried at 120 °C for 3 h in a dryer and then transferred to a rotary kiln for calcination at 500 °C for 4 h to obtain the finished catalyst C - 2. The metal content of C - 2 is NiO 2.5%, MoO₃ 10%, specific surface area 160 m² / g, pore volume 0.8 ml / g, and average pore diameter 35 nm.

[0054] Example 8:

[0055] (1) 10 kg of sodium metaaluminate - aluminum sulfate dry gel (specific surface area 400 ㎡ / g, pore volume 1.0 ml / g), 3 kg of white carbon black (specific surface area 100 ㎡ / g), 3 kg of sesbania powder, 2.5 kg of citric acid, and 10 kg of purified water are added to a kneading machine and kneaded for 45 minutes, then transferred to a screw extruder for forming. The formed carrier is dried at 120 °C for 4 h in a dryer and then calcined at 800 °C for 4 h in a mesh belt kiln to obtain the catalyst carrier.

[0056] (2) 1.0 kg of cobalt acetate (molecular formula: Co(CH3COO)2·4H2O), 1.5 kg of ammonium metatungstate (molecular formula (NH4)6H2W 12 O 40 ·xH2O), 0.8 kg of citric acid, and 9 kg of purified water are used to prepare an impregnation solution, and the solution preparation process is carried out in a reaction kettle.

[0057] (3) Using the equal - volume impregnation method, the solution prepared in step (2) is added to the carrier obtained in step (1). The impregnation process is carried out in a sugar - coating machine. During the impregnation process, the sugar - coating machine is maintained at a certain rotation speed to ensure sufficient contact between the solution and the carrier. After the solution is completely absorbed, it is left standing for 2 h to allow the solute ions to fully diffuse into the internal pores of the carrier. After impregnation, the catalyst is dried at 120 °C for 3 h in a dryer and then calcined at 500 °C for 4 h in a rotary kiln to obtain the finished catalyst C - 3. The metal content of C - 3 is CoO 2.5%, WoO3 10%, specific surface area 160 ㎡ / g, pore volume 0.8 ml / g, and average pore diameter 35 nm.

[0058] Example 9:

[0059] (1) 10 kg of sodium metaaluminate - aluminum sulfate dry gel (specific surface area 400 ㎡ / g, pore volume 1.0 ml / g), 3 kg of white carbon black (specific surface area 100 ㎡ / g), 3 kg of sesbania powder, 2.5 kg of citric acid, and 10 kg of purified water are added to a kneading machine and kneaded for 45 minutes, then transferred to a screw extruder for forming. The formed carrier is dried at 120 °C for 4 h in a dryer and then calcined at 800 °C for 4 h in a mesh belt kiln to obtain the catalyst carrier.

[0060] (2) 0.5 kg of basic cobalt carbonate (molecular formula [2CoCO3·3Co(OH)2·H2O]), 1.2 kg of molybdenum trioxide (molecular formula MoO3), and 0.2 kg of phosphoric acid, and 9 kg of purified water are used to prepare an impregnation solution. The solution temperature is maintained at 90 - 100 °C during this process to promote the dissolution of metal components.

[0061] (3) Using the equal-volume impregnation method, add the solution prepared in step 2 to the carrier obtained in step 1. The impregnation process is carried out in a sugar coating machine. During the impregnation process, maintain a certain rotation speed of the sugar coating machine to ensure sufficient contact between the solution and the carrier. After the solution is completely absorbed, continue to stand for 2 h to allow the solute ions to fully diffuse into the interior of the carrier pores. After impregnation, the catalyst is dried at 120 °C for 3 h in a dryer and then transferred to a rotary kiln for calcination at 500 °C for 4 h to obtain the finished catalyst C-4. The metal content of C-4 is CoO 2.5%, MoO3 10%, the specific surface area is 155 m² / g, the pore volume is 0.75 ml / g, and the average pore diameter is 35 nm.

[0062] Comparative Example 1:

[0063] (1) 15 kg of sodium aluminate-aluminum sulfate dry gel (specific surface area 400 m² / g, pore volume 1.0 ml / g), 3 kg of sesbania powder, 2 kg of acetic acid, and 12 kg of purified water are added to a roller kneader and kneaded for 45 minutes, then transferred to a screw extruder for forming. The formed carrier is dried at 120 °C for 4 h in a dryer and then transferred to a mesh belt kiln for calcination at 550 °C for 4 h to obtain the catalyst carrier.

[0064] (2) 1.0 kg of cobalt acetate (molecular formula: Co(CH3COO)2·4H2O), 1.5 kg of ammonium heptamolybdate (molecular formula (NH4)6Mo7O 24 .4H2O), 0.8 kg of citric acid, and 8 kg of purified water are used to prepare an impregnation solution. The solution preparation process is carried out in a reaction kettle.

[0065] (3) Using the equal-volume impregnation method, add the solution prepared in step 2 to the carrier obtained in step 1. The impregnation process is carried out in a sugar coating machine. During the impregnation process, maintain a certain rotation speed of the sugar coating machine to ensure sufficient contact between the solution and the carrier. After the solution is completely absorbed, continue to stand for 2 h to allow the solute ions to fully diffuse into the interior of the carrier pores. After impregnation, the catalyst is dried at 120 °C for 3 h in a dryer and then transferred to a rotary kiln for calcination at 500 °C for 4 h to obtain the finished catalyst D-1. The metal content of D-1 is CoO 2.5%, MoO3 10%, the specific surface area is 350 m² / g, the pore volume is 0.7 ml / g, and the average pore diameter is 10 nm.

[0066] Comparative Example 2:

[0067] (1) 10 kg of sodium aluminate-aluminum sulfate dry gel (specific surface area 400 m² / g, pore volume 1.0 ml / g), 3 kg of silica white (specific surface area 100 m² / g), 3 kg of sesbania powder, 2.5 kg of citric acid, and 10 kg of purified water are added to a roller kneader and kneaded for 45 minutes, then transferred to a screw extruder for forming. The formed carrier is dried at 120 °C for 4 h in a dryer and then transferred to a mesh belt kiln for calcination at 550 °C for 4 h to obtain the catalyst carrier.

[0068] (2) 1.0 kg of cobalt acetate (molecular formula: Co(CH3COO)2·4H2O), 1.5 kg of ammonium heptamolybdate (molecular formula (NH4)6Mo7O 24 ·4H2O), 0.8 kg of citric acid, and 9 kg of purified water are used to prepare an impregnation solution, and the solution preparation process is carried out in a reaction kettle.

[0069] (3) Using the equal-volume impregnation method, the solution prepared in step (2) is added to the carrier obtained in step (1). The impregnation process is carried out in a sugar coating machine. During the impregnation process, a certain rotation speed of the sugar coating machine is maintained to ensure sufficient contact between the solution and the carrier. After the solution is completely absorbed, it is left standing for another 2 h to allow the solute ions to fully diffuse into the internal pores of the carrier. After impregnation, the catalyst is dried at 120 °C for 3 h in a dryer and then calcined at 500 °C for 4 h in a rotary kiln to obtain the finished catalyst D-2. The metal content of D-2 is CoO 2.5%, MoO3 10%, specific surface area 300 m² / g, pore volume 0.8 ml / g, and average pore diameter 15 nm.

[0070] Comparative Example 3:

[0071] (1) 10 kg of silica white (specific surface area 200 m² / g), 3 kg of sesbania powder, 0.5 kg of water glass (SiO2 27%, Na2O 8.7%), and 10 kg of water are added to a roller kneader and kneaded for 45 minutes, then transferred to a screw extrusion machine for shaping. The shaped carrier is dried at 120 °C for 4 h in a dryer and then calcined at 600 °C for 4 h in a mesh belt kiln to obtain the catalyst carrier.

[0072] (2) 1.0 kg of cobalt acetate (molecular formula: Co(CH3COO)2·4H2O), 1.5 kg of ammonium heptamolybdate (molecular formula (NH4)6Mo7O 24 ·4H2O), 0.8 kg of citric acid, and 8 kg of purified water are used to prepare an impregnation solution, and the solution preparation process is carried out in a reaction kettle.

[0073] (3) Using the equal-volume impregnation method, the solution prepared in step (2) is added to the carrier obtained in step (1). The impregnation process is carried out in a sugar coating machine. During the impregnation process, a certain rotation speed of the sugar coating machine is maintained to ensure sufficient contact between the solution and the carrier. After the solution is completely absorbed, it is left standing for another 2 h to allow the solute ions to fully diffuse into the internal pores of the carrier. After impregnation, the catalyst is dried at 120 °C for 3 h in a dryer and then calcined at 500 °C for 4 h in a rotary kiln to obtain the finished catalyst D-3. The metal content of D-3 is CoO 2.5%, MoO3 10%, specific surface area 150 m² / g, pore volume 0.7 ml / g, and average pore diameter 15 nm.

[0074] The catalysts A1 - A4, B1, C1 - C4, D1 - D3 are loaded into the lower part of the last-stage Claus reactor according to a bed volume ratio of 20%, and respectively according to operating condition (1) with a gas hourly space velocity of 1000 h -1, the bed temperature is 220 °C; in operating condition (2), the gas hourly space velocity is 8000 h -1 , operate at a bed temperature of 180 °C. The hydrogenation conversion rate of SO2 and the selectivity for sulfur production are shown in the following table.

[0075]

Claims

1. A sulfur production catalyst for selective hydrogenation of sulfur dioxide, characterized in that, It includes a catalyst support and a catalyst active component, wherein: The catalyst support includes Al2O3 or a mixture of Al2O3 and SiO2 with a mass fraction of 65 - 95%, wherein Al2O3 exists in the form of δ - Al2O3 and / or θ - Al2O3; The catalyst active component includes one or more elements selected from Group VIIIB of the periodic table with a mass fraction of 1 - 10%, and one or more elements selected from Group VIB of the periodic table with a mass fraction of 5 - 25%.

2. The catalyst according to claim 1, wherein The specific surface area of the catalyst is 100 - 300 m² / g, the pore volume is 0.5 - 1.5 ml / g, and the average pore diameter is 10 - 100 nm.

3. The catalyst according to claim 1, characterized in that, The catalyst active component includes oxides and / or sulfides of iron, cobalt or nickel among the elements in Group VIIIB of the periodic table.

4. The catalyst according to claim 1, characterized in that, The catalyst active component includes oxides and / or sulfides of chromium, molybdenum or tungsten among the elements in Group VIB of the periodic table.

5. A method for preparing a sulfur dioxide selective hydrogenation to sulfur catalyst according to any one of claims 1-4, characterized in that, It includes the following steps: Step 1. Prepare the catalyst support. In a precursor of an oxide or hydrated oxide containing Al and / or Si, after adding a binder and a lubricant, knead, shape, dry and calcine to obtain the catalyst support; Step 2. Prepare the impregnating solution. Using a precursor of an oxide or salt containing the catalyst active component as the raw material, and simultaneously adding an acidic complexing agent or a basic complexing agent, formulate to obtain the impregnating solution; Step 3. Prepare the catalyst. According to the method of equal - volume or excess impregnation, impregnate the catalyst support obtained in Step 1 with the impregnating solution obtained in Step 2, and then dry and calcine to obtain the catalyst.

6. The preparation method according to claim 5, characterized in that, The drying temperature of the catalyst support in Step 1 is 80 - 150 °C, and the calcination temperature is 700 - 1000 °C.

7. The preparation method according to claim 5, characterized in that, The drying temperature of the catalyst in Step 3 is 80 - 150 °C, and the calcination temperature is 200 - 600 °C.

8. The preparation method according to claim 5, characterized in that, The precursor of the oxide or hydrated oxide containing Al in Step 3 includes aluminum hydroxide xerogel and pseudoboehmite; the oxide containing Si is silicon dioxide.

9. The preparation method according to claim 8, characterized in that, The specific surface area and pore volume of the aluminum hydroxide xerogel and pseudoboehmite are 200 - 500 m² / g and 0.3 - 1.5 ml / g respectively, and the specific surface area of the silicon dioxide is 50 - 300 m² / g.

10. A method for using the sulfur dioxide selective hydrogenation to sulfur catalyst according to any one of claims 1-4, characterized in that, Load this catalyst into the last-stage Claus reactor of the Super Claus process sulfur recovery unit and use it under the conditions of an operating temperature of 180 - 220 °C and a gas hourly space velocity of 1000 - 8000 h -1 .

Images