CN103962096B - Remove the preparation method of the adsorbent of indoor low concentration hydrogen sulphide - Google Patents

Abstract

The invention provides a method for preparing an adsorbent for removing indoor low-concentration hydrogen sulfide. Grind 5A molecular sieves to powder at room temperature, soak in hydrochloric acid solution, and then adjust to neutral; add 27g of ammonia water with a concentration of 25wt% to 300-400ml of deionized water, add 5-10g of hexadecyltrimethyl ammonium bromide, and kept stirring to obtain a mixed solution, then added 8-12g of activated 5A molecular sieve into the mixed solution, stirred for 15min, then added 30g of tetraethyl orthosilicate dropwise, then stirred at constant temperature for 1h, and filtered , washing, drying, and roasting to obtain a modified 5A molecular sieve carrier; loading zinc nitrate on the modified 5A molecular sieve carrier, and roasting to obtain a chemical adsorbent in which ZnO is loaded on the modified 5A molecular sieve. The adsorbent obtained by the invention has a large specific surface area, developed pore structure, large adsorption capacity, low cost and is easy to be widely used. It is used to remove low-concentration H ₂ S gas, especially suitable for the removal of hydrogen sulfide gas in closed spaces such as indoors and cabins.

Description

Preparation method of adsorbent for removing indoor low-concentration hydrogen sulfide

technical field

The invention relates to a method for preparing a hydrogen sulfide adsorbent, in particular to a method for preparing a hydrogen sulfide adsorbent for removing low-concentration H ₂ S gas.

Background technique

Hydrogen sulfide is a highly irritating and toxic gas with the smell of rotten eggs, and it is one of the main pollutants in the atmosphere. It not only corrodes metal materials, but also pollutes the environment and endangers human health. Therefore, all countries have strictly controlled the emission standards of hydrogen sulfide. China stipulates that the emission concentration of hydrogen sulfide shall not exceed 0.01mg/m ³ . The removal of hydrogen sulfide, especially the removal of low-concentration hydrogen sulfide, is an urgent problem to be solved. In recent years, domestic and foreign scholars have carried out a lot of research work on the removal of low-concentration hydrogen sulfide. Airtight indoor and cabin air contains low concentration of H ₂ S gas, which requires an adsorbent to remove it. Activated carbon is widely used in gas treatment because of its large specific surface area and ideal adsorption performance. However, because it mainly relies on physical adsorption, when the environment changes, its adsorption effect will change, and the desorption effect is not very obvious, and it cannot eliminate harmful gases in confined spaces very well.

5A molecular sieve is one of the most commonly used air separation adsorbents. Because of its well-developed pore structure, large specific surface area, acid resistance, alkali resistance, and low price, it is suitable for desulfurization indoors and in cabins. The adsorption of sulfur-containing gases such as hydrogen sulfide by 5A molecular sieve is generally physical adsorption, and desorption will occur under certain conditions. Metal oxides are easy to react with hydrogen sulfide to desulfurize, but metal oxides need to be made into porous structures and have a certain strength. Loading metal oxides on the surface of 5A molecular sieve can achieve the purpose of desulfurization.

Contents of the invention

The object of the present invention is to provide a kind of preparation method that has larger specific surface area, well-developed pore structure, large adsorption capacity, low cost, and is easy to widely use for removing indoor low-concentration hydrogen sulfide adsorbent.

The purpose of the present invention is achieved like this:

(1) 5A molecular sieve activation treatment: Grind the 5A molecular sieve into powder at room temperature, add it to hydrochloric acid solution, and soak it with magnetic stirring for 3 hours, then add Na ₂ CO ₃ solution to make the mixture neutral;

(2) Modification of 5A molecular sieve: Add 27g of ammonia water with a concentration of 25wt% to 300-400ml of deionized water, stir magnetically at a constant temperature of 23-27°C for 15min, and slowly add 5-10g of hexadecyl trimethyl bromide Ammonium, continue stirring for 15 minutes to obtain a mixed solution, then slowly add 8-12 g of activated 5A molecular sieves into the mixed solution, continue stirring at a constant temperature for 15 minutes, then add 30 g of ethyl orthosilicate dropwise, and then stir at a constant temperature for 1 hour, The modified 5A molecular sieve carrier was prepared by suction filtration, washing, drying and roasting;

(3) Zinc nitrate is loaded on the modified 5A molecular sieve carrier, and calcined to obtain a chemical adsorbent in which ZnO is loaded on the modified 5A molecular sieve.

The dropwise addition of 30 g of ethyl orthosilicate was completed within 20-30 minutes.

The calcination temperature in the modification process of the 5A molecular sieve is 550°C.

The calcining temperature after the zinc nitrate is loaded on the modified 5A molecular sieve carrier is 400-450°C.

The loading of zinc nitrate on the modified 5A molecular sieve carrier refers to ZnO 10wt%, 20wt%, 30wt%, 40wt% on the prepared modified 5A molecular sieve carrier.

The invention provides an adsorbent with a modified 5A molecular sieve as a carrier, which has a large specific surface area, developed pore structure, large adsorption capacity, low cost and is easy to be widely used. It is used to remove low-concentration H ₂ S gas, especially suitable for the removal of hydrogen sulfide gas in closed spaces such as indoors and cabins.

The invention loads zinc oxide on the surface of the modified 5A molecular sieve to achieve the purpose of chemical adsorption.

5A molecular sieve is a kind of porous material, which is composed of CaO·Na ₂ O·Al ₂ O ₃ ·SiO ₂ and so on. Adding a certain amount of acid can discharge various impurities in the structural pores and play a certain role in opening pores. The specific surface area is further increased, and the adsorption effect is increased.

Compared with the same type of chemical adsorbents, the present invention has the following advantages. (1) Large adsorption capacity: Since the zinc oxide/modified 5A molecular sieve chemical adsorbent of the present invention has a large specific surface area, it has a surface effect so that zinc oxide can be well loaded on the surface of the modified 5A molecular sieve. Zinc oxide reacts chemically with H ₂ S gas, which has a good chemical adsorption effect. (2) Energy saving and material saving: because the invention utilizes relatively cheap materials on the market. And because of its good adsorption, it has good performance in removing H ₂ S. The amount of adsorbent is less than that of the same type of adsorbent, and the effect of material saving is obvious.

Description of drawings

Fig. 1 is a graph comparing breakthrough curves of chemical adsorbents prepared by the present invention at 298K loaded with different contents of ZnO to adsorb H ₂ S gas.

Fig. 2 is a graph comparing the breakthrough curves of the chemical adsorbent prepared by the present invention loaded with 30wt% ZnO at different calcination temperatures at 298K to adsorb H ₂ S gas.

Detailed ways

Technical scheme of the present invention mainly comprises the steps:

The preparation method of modified 5A molecular sieve loaded zinc oxide chemical adsorbent comprises the following steps:

(1) 5A molecular sieve activation treatment: Grind 5A molecular sieve to powder at 25°C, add it to hydrochloric acid solution, and soak for 3 hours with magnetic stirring, then add Na ₂ CO ₃ solution to make the mixture neutral.

More specifically, the activation method includes the following steps: grind 5A molecular sieve (spherical) to powder at room temperature, add it to 2mol/L hydrochloric acid, and mix and stir for 3 hours for activation treatment. Add 1mol/L Na ₂ CO ₃ solution into the hydrochloric acid solution containing molecular sieves to neutralize. Then put it into a blast drying oven and dry at 105°C for 24 hours to obtain a dry product, grind it to a powder state and sieve it with a 200-mesh standard sieve to obtain a powder, which is ready for use.

(2) Modification of 5A molecular sieve: Weigh 27g of ammonia water (25wt%) into 300-400ml of deionized water, and stir magnetically at a constant temperature of 23-27°C for 15min. Then take by weighing 5-10g CTMAB (cetyltrimethylammonium bromide) and slowly join in the solution, continue stirring 15min. Then, the dried 5A molecular sieve (8-12g) was slowly added to the mixture, and kept stirring at constant temperature for 15 minutes. Make the molecular sieve mix well. Weigh 30g tetraethyl orthosilicate (TEOS) and add it dropwise to the stirred mixture (20-30min). Then stir at constant temperature for 1h. The mixture was suction filtered, washed and dried. The modified 5A molecular sieve carrier was prepared by calcining (the calcining temperature was 550°C).

(3) Zinc nitrate is loaded on the prepared carrier according to ZnO10wt%, 20wt%, 30wt%, 40wt%. The chemical adsorbents with different contents of ZnO supported on modified 5A molecular sieves were obtained by roasting in a muffle furnace (calcination temperature was 400-450°C).

The present invention will be further described below.

Example 1

Grind the 5A molecular sieve (spherical) to powder at 25°C, add it into 2mol/L hydrochloric acid, and stir with magnetic force for 3h for activation. Then add Na ₂ CO ₃ solution to neutralize. Then the sample was put into a blast drying oven at 105°C for 12 hours to obtain a dry product, which was ground to a powder and sieved with a 200-mesh standard sieve to obtain a powder for use.

Preparation of the modified 5A molecular sieve carrier: Weigh 27g of ammonia water and add it to 300-400ml of deionized water, and stir at a constant temperature of 23-27°C for 15min. Then take by weighing 5-10g CTMAB and slowly add in the solution, continue to stir 15min. Then, the dried 5A molecular sieve (8-12g) was slowly added to the mixture, and kept stirring at constant temperature for 15 minutes. Make the molecular sieve mix well. Weigh 30g of TEOS and add it dropwise to the stirred mixture (20-30min). Then stir at constant temperature for 1h. The mixture was suction filtered, washed and dried. Calcined modified 5A molecular sieve carrier (calcination temperature is programmed, 25-300°C (30min), 300°C (30min), 300-550°C (30min), 550°C (300min)). Then the calcined sample was calcined in a muffle furnace (the calcining temperature is 400-450° C.) to obtain the modified 5A molecular sieve carrier.

Example 2

The 5A molecular sieve carrier was prepared as described in Example 1. Zinc nitrate was loaded on the prepared carrier according to ZnO10wt%. The modified 5A molecular sieve chemical adsorbent loaded with 10wt% ZnO was obtained by roasting in a muffle furnace (the roasting temperature was 400-450°C).

Example 3

The 5A molecular sieve carrier was prepared as described in Example 1. Zinc nitrate was loaded on the prepared 5A molecular sieve carrier according to ZnO20wt%. The modified 5A molecular sieve chemical adsorbent loaded with 20wt% ZnO was obtained by roasting in a muffle furnace (the roasting temperature was 400-450°C).

Example 4

The 5A molecular sieve carrier was prepared as described in Example 1. Zinc nitrate is loaded on the prepared carrier according to ZnO30wt%. The modified 5A molecular sieve chemical adsorbent loaded with 30wt% ZnO was obtained by roasting in a muffle furnace (the roasting temperature was 400-450°C).

Example 5

The 5A molecular sieve carrier was prepared as described in Example 1. Zinc nitrate was loaded on the prepared carrier according to ZnO40wt%. The modified 5A molecular sieve chemical adsorbent loaded with 40wt% ZnO was obtained by calcining in a muffle furnace (the calcining temperature was 400°C).

Example 6

The 5A molecular sieve carrier was prepared as described in Example 1. Zinc nitrate is loaded on the prepared carrier according to ZnO30wt%. The modified 5A molecular sieve chemical adsorbent loaded with 30wt% ZnO was obtained by calcining in a muffle furnace (the calcining temperature was 200°C) at the calcining temperature of 200°C.

Example 7

The 5A molecular sieve carrier was prepared as described in Example 1. Zinc nitrate was loaded on the prepared carrier at 30wt% zinc oxide. The modified 5A molecular sieve chemical adsorbent loaded with 30wt% zinc oxide was obtained by calcining in a muffle furnace (calcination temperature is 300°C) at a calcining temperature of 300°C.

Example 8

The 5A molecular sieve carrier was prepared as described in Example 1. Zinc nitrate is loaded on the prepared carrier according to ZnO30wt%. The modified 5A molecular sieve chemical adsorbent loaded with 30wt% ZnO was obtained by calcining in a muffle furnace (the calcining temperature was 400°C) and the calcining temperature was 400°C.

Example 9

The 5A molecular sieve carrier was prepared as described in Example 1. Zinc nitrate is loaded on the prepared carrier according to ZnO30wt%. The modified 5A molecular sieve chemical adsorbent loaded with 30wt% ZnO was obtained by calcination in a muffle furnace (calcination temperature was 250°C).

The breakthrough test of H ₂ S gas was carried out on the adsorbent materials prepared in Examples 1-5 above. Figure 1 is the breakthrough curve of the chemical adsorbent obtained by loading modified 5A molecular sieve with different contents of ZnO at 25°C (inlet gas concentration is 145ppm. 0.5g adsorbent, flow rate 150ml/min), it can be seen from Figure 1 that the The chemical adsorbent prepared by the present invention has high adsorption performance, and the chemical adsorbent prepared in Example 4 has better adsorption performance and the longest breakthrough time. Figure 2 shows the breakthrough experimental curves of adsorbents prepared at different calcination temperatures at 25°C (inlet gas concentration is 125ppm. 0.5g adsorbent, flow rate 150ml/min), it can be seen that when the calcination temperature is 250 The breakthrough time at ℃ is the longest, and the adsorption effect of the chemical adsorbent is the best.

To sum up, the chemical adsorbent with high adsorption performance prepared by the present invention has a long breakthrough time, which is obviously better than the same type of adsorbents on the market.

Claims (5)

1. remove a preparation method for the adsorbent of indoor low concentration hydrogen sulphide, it is characterized in that:

(1) 5A molecular sieve activation process: be ground to Powdered by 5A molecular sieve under room temperature, adds in hydrochloric acid solution, and magnetic agitation soaks 3 hours, then adds Na ₂cO ₃solution makes mixed liquor be neutral;

(2) modification of 5A molecular sieve: be that the ammoniacal liquor of 25wt% joins in the deionized water of 300-400ml by 27g concentration, 23-27 DEG C of temperature constant magnetic stirring 15min, slowly add 5-10g softex kw, Keep agitation 15min obtains mixed liquor, then the 5A molecular sieve of activated for 8-12g process is slowly joined in described mixed liquor, continue constant temperature and stir 15min, dropwise add 30g ethyl orthosilicate again, then constant temperature stirs 1h, through suction filtration, washing, drying, roasting obtains modification 5A molecular sieve carrier;

(3) zinc nitrate is carried on described modification 5A molecular sieve carrier, roasting obtains the chemosorbent that ZnO is carried on modification 5A molecular sieve, and described being carried on by zinc nitrate described modification 5A molecular sieve carrier refers to be carried on prepared modification 5A molecular sieve carrier by ZnO10wt%, 20wt%, 30wt%, 40wt%.

2. the preparation method removing the adsorbent of indoor low concentration hydrogen sulphide according to claim 1, is characterized in that: the described 30g ethyl orthosilicate that dropwise adds completes within the 20-30min time.

3. the preparation method removing the adsorbent of indoor low concentration hydrogen sulphide according to claim 1 and 2, is characterized in that: the sintering temperature of roasting described in the modifying process of 5A molecular sieve is 550 DEG C.

4. the preparation method removing the adsorbent of indoor low concentration hydrogen sulphide according to claim 1 and 2, is characterized in that: zinc nitrate be carried on modification 5A molecular sieve carrier after the sintering temperature of roasting be 400-450 DEG C.

5. the preparation method removing the adsorbent of indoor low concentration hydrogen sulphide according to claim 3, is characterized in that: zinc nitrate be carried on modification 5A molecular sieve carrier after the sintering temperature of roasting be 400-450 DEG C.