CN108246298A - A kind of method of nano lamellar solid base removing carbonyl sulfur - Google Patents

Abstract

The present invention relates to a kind of method that nano lamellar solid base removes carbonyl sulfur in gas, the method for carbonyl sulfur is in this nano lamellar solid base removing gas：Carbonyl sulfur is 40 in temperature under the effect of nano lamellar catalyzed by solid base in industrial chemicals or tail gas of sulphur^oC‑80^oC, water and carbonyl sulfur molar ratio are 1.1:1‑2:1st, the material gas air speed containing COS is 1.0 4000h^‑1Under conditions of, hydrolysis and oxidation reaction occurs, the oxidation through oxygen in water is converted into sulphur simple substance and sulfate after COS hydrolysis, realizes the removing of COS, and carbonyl sulfide removal rate is up to more than 99.5%；Nano lamellar solid base after inactivation regenerates after soda-dip, washing, drying and roasting, and the solid base after regeneration recycles.Nano lamellar oxide solid alkali prepared by the present invention, crystal size distribution range is relatively narrow, large specific surface area, and dispersion degree is high, and preparation process is simple.

Description

A method for removing carbonyl sulfide with nano-layered solid base

technical field

The invention relates to the field of removing organic sulfur from chemical raw material gas or sulfur tail gas, in particular to a method for removing carbonyl sulfide in gas with a nano-layered solid base.

Background technique

With the rapid development of the economy, the contradiction between energy supply and demand has become increasingly prominent, and the scientific and rational use of high-sulfur energy has received extensive attention. In the chemical raw material gas prepared from coal, petroleum and natural gas and in the subsequent desulfurization process, sulfur tail gas contains a large amount of sulfide, which is mainly divided into two categories: organic sulfur and inorganic sulfur. Organic sulfur includes carbonyl sulfide, carbon disulfide, thiophene, Mercaptans, etc., inorganic sulfur mainly refers to hydrogen sulfide. Among them, carbonyl sulfide accounts for 80-90% of the total organic sulfur. Its existence not only easily causes the corrosion of raw gas pipelines, reduces the service life of equipment, but also easily causes poisoning of downstream catalysts, increasing production costs. Therefore, carbonyl sulfide The removal of carbonyl sulfide is the main problem to be solved in the process of deep purification of raw material gas. In addition, as a major organic sulfur in industrial gases, carbonyl sulfide discharged into the atmosphere will be generated after a series of chemical and photochemical reactions, resulting in Environmental pollution threatens human health and welfare. Therefore, the research on the removal of carbonyl sulfide has important environmental significance.

The commonly used COS removal methods include reduction method, hydrolysis method, absorption method, adsorption method and oxidation method. The reduction method uses H ₂ to reduce COS to H ₂ S. This method has a high conversion rate, but the cost is high and there are certain side reactions. The absorption method is to use alkaline organic amine solution to absorb acidic COS gas. This method has fast absorption speed and low cost, but has poor desulfurization selectivity and high energy consumption, and is mainly suitable for coarse desulfurization. Adsorption method is the process of using porous solid material to adsorb low concentration COS, enriching it on the solid surface and separating it from other components. Commonly used adsorbents include activated carbon, molecular sieves, zinc oxide, iron oxide, and manganese oxide. This method has high desulfurization depth and large treatment capacity, but requires frequent regeneration and the regeneration conditions are relatively harsh. The oxidation method is to oxidize COS to generate other easily removable sulfides and then try to remove them. The process is relatively complicated.

The hydrolysis method is a technology that first reacts COS with H ₂ O, and then tries to remove the generated H ₂ S. Commonly used COS hydrolysis catalysts include metal oxide-based supports represented by γ-Al ₂ O ₃ and TiO ₂ and non-metal oxide-based supports represented by activated carbon, which have high activity at room temperature, wide use temperature range, and anti-toxicity. Strong, high conversion and absorption efficiency of organic sulfur and energy saving. The Chinese invention patent application with publication number 106031868 A discloses a catalyst for the hydrolysis of carbonyl sulfide and its preparation method and application. It uses activated alumina or titanium oxide as a carrier and base Carbonyl sulfide hydrolysis catalyst with metal, alkaline earth metal or rare earth metal oxide as the active component. The catalyst has good gas source applicability, strong resistance to sulfation, and good removal effect, but it is not suitable for low COS concentration Happening. The Chinese invention patent application with the publication number 101703928 A discloses a method for preparing a carbon-based catalyst for low-temperature hydrolysis of carbonyl sulfide. This method uses activated carbon as a carrier, and after being treated with lye and activated, COS and its The H ₂ S produced after hydrolysis is low in cost, but it is only applicable to the case of high COS concentration. The Chinese invention patent with the notification number 104667926 B discloses a method for preparing a low-temperature carbonyl sulfide hydrolysis catalyst with modified γ-FeOOH as the active component. The catalyst is prepared by co-precipitation and is applicable to CO ₂ In the case of higher concentration, the catalytic activity still needs to be improved.

It is generally believed that the essence of the carbonyl sulfide hydrolysis reaction is a base-catalyzed reaction, and the basic center on the surface of the catalyst is the active center of COS hydrolysis. However, the previous hydrolysis method is difficult to achieve fine desulfurization and the process is complicated.

Contents of the invention

The purpose of the present invention is to provide a method for removing carbonyl sulfide in gas with a nano-layered solid base, which is used to solve the existing method for removing COS by hydrolysis It is difficult to achieve fine desulfurization, and the process is complicated.

The technical solution adopted by the present invention to solve its technical problems is: the method for removing carbonyl sulfide in gas by this nano-layered solid base:

Carbonyl sulfide in chemical raw materials or sulfur tail gas is catalyzed by nano-layered solid base, at a temperature of 40 ^o C-80 ^o C, the molar ratio of water and carbonyl sulfide is 1.1:1-2:1, and the chemical raw material gas containing COS Under the condition of space velocity of 1.0-4000h ^-1 , hydrolysis and oxidation reactions occur. After COS is hydrolyzed, it is converted into sulfur element and sulfate through the oxidation of dissolved oxygen in water, and the removal of COS is realized. The removal rate of carbonyl sulfide reaches 99.5%. Above; the deactivated nano-layered solid alkali is regenerated after lye impregnation, washing, drying and roasting, and the regenerated solid alkali is recycled;

The preparation method of the nano-layered metal oxide solid base is: prepare Mg(NO ₃ ) ₂ and Fe(NO ₃ ) ₃ solutions, the concentration of Mg(NO ₃ ) ₂ and Fe(NO ₃ ) ₃ solutions is 0.01mol/L- 2.0mol/L, and Mg/Fe molar ratio is 1:4-6:1, at the same time add M(NO ₃ ) ₂ for metal doping, M is doping metal, M/Mg molar ratio is 1:10-5 : 1, forming a hydrotalcite synthetic solution, adjusting the pH value of the solution to alkalescence, carrying out hydrothermal synthesis after stirring, the obtained solid product is washed and dried to obtain nanoscale metal-doped MgFe monolayer hydrotalcite, roasting Afterwards, a nano-layered solid base is obtained.

The synthesis conditions of the nanoscale metal-doped MgFe single-layer hydrotalcite in the above scheme are: crystallization at 100 ^o C-280 ^o C for 10h-36h, and the solid product obtained by centrifugation is washed with deionized water and ethanol for 3-5 Once, dry at 80 ^o C-120 ^o C for 6h-24h to obtain nano-scale metal-doped MgFe single-layer hydrotalcite.

In the above solution, the doping metal M is any one of Zn, Cu, Ni and Mn.

In the above scheme, the nanoscale metal-doped MgFe single-layer hydrotalcite is calcined at 300 ^o C-450 ^o C for 3 h-12 h to obtain a nano-layered solid base.

The method for adjusting the pH value of the hydrotalcite synthesis solution to alkaline in the above scheme is: add 0.1 mol/L-2 mol/L KOH solution dropwise until the pH value of the hydrotalcite synthesis solution is 8.0-13.0.

The regeneration method of the nano-layered solid base in the above scheme is: soak the deactivated nano-layered solid base catalyst in K ₂ CO ₃ , KOH or a mixed solution of the two at 20 ^o C-80 ^o C for 1h- 24. Wash with deionized water for 3-5 times until neutral, dry at 120 ^o C for 1h-24h, and then bake at ^300oC - ^450oC for 3h-12h to realize the regeneration of the solid alkali catalyst, and the regenerated nano-layer The solid base can be recycled.

The present invention has the following beneficial effects:

1. The present invention adopts hydrothermal synthesis to prepare metal-doped MgFe nano-layered hydrotalcite, and obtains nano-layered oxide solid base after roasting. The crystal size distribution range is narrow, the specific surface area is large, and the dispersion degree is high. The preparation process Simple and low cost.

2. The present invention finally converts COS into elemental sulfur and sulfate through the synergistic effect of COS hydrolysis and further oxidation, and has a high COS removal rate.

3. In the present invention, the surface of the catalyst is deactivated due to the coverage of the sulfur element and sulfate on the surface. The catalyst can be regenerated by dipping in alkaline solution, washing, drying and roasting, and the regenerated catalyst can be recycled.

4. The present invention prepares a nano-layered solid base. The solid base has a large specific surface area, dispersion and alkalinity. It is used to catalyze the hydrolysis of COS. The applicable temperature is low and has broad application prospects. It expands the hydrolysis of COS catalyst range.

Description of drawings

Fig. 1 is the evaluation result of COS removal by NiMgFe oxide solid base;

Fig. 2 is the evaluation result of COS removal by ZnMgFe oxide solid base;

Figure 3 is the evaluation result of COS removal by CuMgFe oxide solid base.

Detailed ways

Below in conjunction with accompanying drawing, the present invention will be further described:

Example 1

Weigh 4.096g Mg(NO ₃ ) ₂ 6H ₂ O, 2.020g Fe(NO ₃ ) ₃ 9H ₂ O and 1.163 g Ni(NO ₃ ) ₂ 6H ₂ O in 50 mL deionized water and stir well , n _Ni : n _Mg : n _Fe =4:16:5 in the mixed solution; 1.0 mol/L KOH was added dropwise until the pH value of the solution was 11, and the evenly stirred mixed solution was transferred to a reaction kettle at 150 ^o C After crystallization for 24 h, the centrifuged solid product was washed 5 times with deionized water and ethanol respectively, and dried at 110 ^o C for 12 h to obtain nanoscale metal-doped NiMgFe single-layer hydrotalcite (wherein Ni-doped The impurity mass fraction is 26.1%). The prepared hydrotalcite was calcined at 400 ^o C for 8 hours to obtain a nano-layered NiMgFe solid base.

The reaction was carried out under the conditions that the reaction temperature was 50 ^o C, _the molar ratio of water and carbonyl sulfide was 1.5:1, and the space velocity of the sulfur tail gas containing 284 μg/g carbonyl sulfide was 1000 h ^-1 . The COS removal rate of S concentration is shown in Figure 1.

The deactivated nano-layered NiMgFe solid base catalyst was impregnated in 1 mol/L KOH at 45 ^o C for 6 h, washed 5 times with deionized water to neutrality, dried at 120 ^o C for 6 h, and then placed in After calcination at 350 ^o C for 8 hours, the solid base catalyst can be regenerated.

Example 2

Weigh 10.24g Mg(NO ₃ ) ₂ 6H ₂ O, 4.85g Fe(NO ₃ ) ₃ 9H ₂ O and 2.38 g Zn(NO ₃ ) ₂ 6H ₂ O in 50 mL deionized water and stir well , n _Zn : n _Mg : n _Fe =2:10:3 in the mixed solution; 0.5 mol/L KOH was added dropwise until the pH value of the solution was 10.5, and the evenly stirred mixed solution was transferred to a reaction kettle at 180 ^o C After the reaction was finished, the solid product obtained by centrifugation was washed three times with deionized water and ethanol, and dried at 110 ^o C for 24 hours to obtain nanoscale metal-doped ZnMgFe single-layer hydrotalcite (where Zn The doping mass fraction is 24.2%). The prepared hydrotalcite was calcined at 400 ^o C for 12 h to obtain a nano-layered ZnMgFe solid base.

The reaction temperature is 45 ^o C, the molar ratio of water and carbonyl sulfide is 1.4:1, and the sulfur tail gas containing 284 μg/g carbonyl sulfide is reacted under the condition of space velocity of 2400h ^-1 . The COS and H ₂ S at the import and export The COS removal rate calculated from the concentration is shown in Figure 2.

Immerse the deactivated nano-layered ZnMgFe oxide solid base catalyst in 1mol/L _K2CO3 at 30 ^o C for 6 hours, wash it with deionized water for 5 _times to neutrality, and dry it at 120 ^o C for 12 hours , and then roasted at 400 ^o C for 12h, the solid base catalyst was regenerated.

Example 3

Weigh 20.48g of Mg(NO ₃ ) ₂ ·6H ₂ O, 12.12g of Fe(NO ₃ ) ₃ ·9H ₂ O and 2.416g of Cu(NO ₃ ) ₂ ·3H ₂ O in 100 mL of deionized water and stir evenly. In the mixed solution, n _Cu : n _Mg : n _Fe =1:8:3; add 1 mol/L KOH and K ₂ CO ₃ mixed solution (wherein the mass fraction of KOH is 50%) dropwise until the pH value of the solution is 11, and the The uniformly stirred mixed solution was transferred to a reaction kettle and crystallized at 220 ^o C for 16 h. After the reaction, the solid product obtained by centrifugation was washed with deionized water and ethanol for 5 times, and dried at 80 ^o C for 24 h to obtain nano Metal-doped CuMgFe single-layer hydrotalcite (in which Cu doping mass fraction is 15.1%). The prepared hydrotalcite was calcined at 380 ^o C for 6h to obtain a nano-layered CuMgFe solid base.

The reaction temperature is 60 ^o C, the molar ratio of water and carbonyl sulfide is 1.2:1, and the sulfur tail gas containing 284 μg/g carbonyl sulfide is reacted under the condition of space velocity of 3200h ^-1 . After testing the COS and H ₂ S at the import and export The COS removal rate calculated from the concentration is shown in Figure 3.

The deactivated nano-layered CuMgFe solid base catalyst was impregnated in 2 mol/L KOH at 50 ^o C for 12 h, washed 5 times with deionized water to neutrality, dried at 120 ^o C for 12 h, and then placed in Calcined at 400 ^o C for 6h, the solid base catalyst was regenerated.

Claims (6)

1. a kind of method of carbonyl sulfur in nano lamellar solid base removing gas, it is characterised in that：This nano lamellar solid base The method for removing carbonyl sulfur in gas：

Carbonyl sulfur is 40 in temperature under the effect of nano lamellar catalyzed by solid base in industrial chemicals and tail gas of sulphur^oC-80^oC, water It is 1.1 with carbonyl sulfur molar ratio:1-2:1st, the material gas containing COS or tail gas of sulphur air speed are 1.0-4000h^-1Condition Under, hydrolysis and oxidation reaction occurs, the oxidation through oxygen in water is converted into sulphur simple substance and sulfate after COS hydrolysis, real The removing of existing COS, carbonyl sulfide removal rate is up to more than 99.5%；Nano lamellar solid base after inactivation is through soda-dip, washing, dry It is regenerated after dry and roasting, the solid base after regeneration recycles；

The preparation method of nano lamellar metal oxide solid alkali is：Prepare Mg (NO₃)₂With Fe (NO₃)₃Solution, Mg (NO₃)₂With Fe(NO₃)₃Solution concentration is 0.01mol/L-2.0mol/L, and Mg/Fe molar ratios are 1:4-6:1, while add M (NO₃)₂Into Row metal adulterates, and M is doping metals, and M/Mg molar ratios are 1:10-5:1, hydrotalcite synthetic solvent is formed, adjusts the solution ph To alkalinity, hydrothermal synthesis is carried out after stirring evenly, obtained solid product is washed, nano level metal doping is obtained after drying MgFe individual layer shape hydrotalcites, obtain nano lamellar solid base after roasting.

2. the method for carbonyl sulfur in nano lamellar solid base removing gas according to claim 1, it is characterised in that：It is described Nano level metal doping MgFe individual layer shape hydrotalcite synthesis conditions be：100^oC-280^oCrystallization 10h-36h under C, centrifugation point 3-5 times from obtained solid matter with deionized water and ethyl alcohol washing, 80^oC-120 ^oDry 6h-24h, obtains nanometer grade gold under C Belong to the MgFe individual layer shape hydrotalcites of doping.

3. the method for carbonyl sulfur in nano lamellar solid base removing gas according to claim 2, it is characterised in that：It is described Doping metals M be Zn, Cu, Ni and Mn in any one.

4. the method for carbonyl sulfur in nano lamellar solid base removing gas according to claim 3, it is characterised in that：Institute The MgFe individual layer shape hydrotalcites of nano level metal doping stated are 300^oC-450^oC roasts 3 h-12h and obtains nano lamellar solid Alkali.

5. the method for carbonyl sulfur in nano lamellar solid base removing gas according to claim 4, it is characterised in that：It is described Adjustment hydrotalcite synthetic solvent pH value to alkalinity method be：It is added dropwise using 0.1 mol/L-2 mol/L KOH solutions It is 8.0-13.0 to hydrotalcite synthetic solvent pH value.

6. the method for carbonyl sulfur in nano lamellar solid base removing gas according to claim 5, it is characterised in that：It is described The regeneration method of nano lamellar solid base be：The nano lamellar solid base catalyst of inactivation is used into K₂CO₃, one kind in KOH Or the two mixed solution is 20^oC-80 ^oC impregnates 1h-24,3-5 times is washed to neutrality through deionized water, 120 ^oC dries 1h- For 24 hours, then 300^oC-450^oC roasts 3h-12h, realizes the regeneration of solid base catalyst, the nano lamellar solid base after regeneration It recycles.