Preparation and application methods of modified activated carbon adsorbent applied to removal of thioether compounds in styrene

Abstract

The invention discloses preparation and application methods of a modified activated carbon adsorbent applied to removal of thioether compounds in styrene. The activated carbon adsorbent is characterized in that activated carbon is modified by using an acid and metal ion compounding method, the acid is selected from one of sulfuric acid, nitric acid and hydrochloric acid, the concentration of the acid is 1-7 mol / L, the metal ion is selected from one of Cu < 2 + >, Fe < 3 + > and Zn < 2 + >, and the loading capacity of the metal ion is 0.1-20 wt% of that of the activated carbon; according to the application method, modified activated carbon is taken as an adsorbent, and thioether is adsorbed through sigma complexation in a batch reactor at 30 DEG C, so that the purpose of removing thioether compounds in styrene is achieved. The adsorbent does not adsorb styrene and adsorbs at 30 DEG C, so that the styrene is not easy to be oligomerized, the loss of the styrene is avoided, and the static sulfur capacity of the adsorbent is improved from 2.5 mg / g which is not modified to 25mg / g after modification.

Description

Technical Field

[0001] The invention belongs to the technical field of unsaturated hydrocarbon desulfurization, and in particular relates to a preparation and application method of a modified activated carbon adsorbent used for removing sulfide compounds in styrene. Background Art

[0002] Styrene is an important organic chemical raw material, which is widely used in many fields due to its excellent physical and chemical properties. The main production methods of styrene are ethylbenzene dehydrogenation, propylene oxide / styrene co-production and petroleum cracking C8 extraction. Among them, ethylbenzene dehydrogenation is the most commonly used styrene production method in industry, accounting for about 80% of styrene production. The method is to heat ethylbenzene to about 470-500°C under the action of a catalyst, and then carry out a dehydrogenation reaction to generate styrene and hydrogen. However, this method has high energy consumption and many by-products. The propylene oxide / styrene co-production method is that ethylbenzene is oxidized to ethylbenzene hydroperoxide in a liquid phase reactor, and then reacts with propylene to generate propylene oxide and α-methylbenzyl alcohol. α-methylbenzyl alcohol is dehydrated to obtain styrene. This method has low energy consumption and large economic scale, but it has many by-products and the economic benefits of propylene oxide are higher than styrene. It cannot be used as a production method for preparing styrene alone. The C8 extraction method only accounts for about 2% of production. The main reason is that the sulfur content in styrene produced by the extraction method using the C8 fraction from petroleum cracking as raw material is 30ppm to 300ppm. The sulfides therein are mainly malodorous sulfides including mercaptans and sulfides, which cause the product to have a strong odor, seriously affecting the chemical utilization of styrene products and the production of downstream products. In recent years, the production of ethylene has increased significantly, resulting in an increase in the production of pyrolysis gasoline, and thus a significant increase in the production of styrene. Separating styrene from pyrolysis gasoline has considerable economic benefits. Reducing the content of sulfides in styrene can significantly improve the quality of styrene prepared by the extraction method and promote chemical production.

[0003] Hydrodesulfurization is the main desulfurization method for gasoline and diesel. It uses hydrogen to react with sulfide in the presence of a catalyst to convert sulfide into hydrogen sulfide and alcohol. Since the temperature required for the process is generally 200-400°C and the pressure is generally between 10-20Mpa, styrene will react with hydrogen to form ethylbenzene, or a serious polymerization reaction will occur. Oxidative desulfurization of ether is to oxidize sulfide into sulfur oxides by using an oxidant to increase its polarity, and then remove the sulfur oxides by extraction. However, the oxidant will also cause styrene to be oxidized into harmful substances such as benzaldehyde and benzoic acid. On the other hand, the temperature required for the oxidative desulfurization reaction is higher than that of hydrodesulfurization, which will cause styrene to polymerize rapidly.

[0004] Adsorption desulfurization generally reacts at room temperature and pressure, which can effectively avoid styrene oxidation, hydrogenation or polymerization, and is more suitable for removing sulfides in styrene. Invention patent CN202110127796.7 discloses a copper-cerium bimetallic modified 4A molecular sieve desulfurization adsorbent and its preparation method and application, which is characterized by using copper-cerium bimetallic modified 4A molecular sieve for adsorption desulfurization, and adsorbing organic sulfur through π complexation and SM bond coordination. However, π complexation adsorption may lead to competitive adsorption between styrene and organic sulfide, which reduces the styrene content and is not suitable for removing sulfide compounds in styrene. Summary of the invention

[0005] The present invention provides a preparation and application method of a modified activated carbon adsorbent for removing sulfide compounds from styrene, which is characterized in that the activated carbon is modified by using an acid and a metal. The acid treatment can effectively remove impurities on the activated carbon, increase its specific surface area, and effectively improve the dispersion of the metal loaded thereafter, and the metal is attached to the activated carbon after the acid treatment by an impregnation method. During adsorption desulfurization, the metal on the adsorbent adsorbs the sulfide through σ complexation, and does not react with styrene in the system, thereby effectively reducing the loss of styrene.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] The present invention provides a preparation and application method of a modified activated carbon adsorbent for removing sulfide compounds from styrene. The preparation method is as follows:

[0008] The activated carbon and the acid solution are placed in a reaction device, pretreated at 60-80°C for 2-8 hours, washed to neutrality and dried at 100°C for 12 hours, and the pretreated activated carbon and Cu 2+ The solution is placed in a reaction device and impregnated at 30°C for 12 to 24 hours to obtain modified activated carbon. 2+ The mass of the modified activated carbon is 7-13% of the mass of the activated carbon, the modified activated carbon is dried at 60-120°C for 2-12h, and then the dried activated carbon is placed in a tubular furnace and calcined under inert gas or vacuum conditions at a temperature of 200-400°C and a calcination time of 2-6h to obtain a modified activated carbon adsorbent.

[0009] Its application method is:

[0010] Weigh 1g of modified activated carbon adsorbent, mix it with a styrene / ethyl sulfide solution with a sulfur content of 2000ppm at a solid-liquid ratio of 1:15, and adsorb it in a 30℃ water bath for 5h. Then take a sample of the adsorbed styrene, and use an ultraviolet fluorescence sulfur analyzer to determine the sulfide content in the sample, and calculate the sulfide removal rate.

[0011] Compared with the prior art, the beneficial technical effects of the present invention are:

[0012] (1) The process of using activated carbon to adsorb sulfide removal is simple, the reaction is mild and controllable, and the sulfide can be removed at room temperature and pressure. It has strong selectivity for the sulfide in the styrene system, does not react with styrene, and will not cause the loss of styrene.

[0013] (2) Compared with unmodified activated carbon, the static sulfur capacity of modified activated carbon for thioether increased from 2.5 mg / g to 25 mg / g, and the adsorption performance was enhanced, which was more conducive to the removal of thioether compounds in styrene.

[0014] (3) The preparation process of this modified activated carbon is simple and easy to operate. The maximum preparation temperature does not exceed 60°C. The preparation process has low energy consumption and high economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a comparison chart of the removal rates of Example 10, Example 11, Example 12 and Example 13 of the present invention;

[0016] Figure 2 It is a comparison chart of the removal rates of Example 13, Example 14, Example 15 and Example 16 of the present invention;

[0017] Figure 3 This is a comparison chart of the removal rates of Example 11, Example 17 and Example 18 of the present invention; DETAILED DESCRIPTION

[0018] The present invention is further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0019] Examples 1-9 are examples of preparing modified activated carbon, and Examples 10-18 are examples of applying modified activated carbon.

[0020] Example 1

[0021] a. Prepare 25 mL of 6.7 mol / L nitric acid solution and place it in a reactor. Then weigh 6.2 g of activated carbon (coconut shell) and add it to the reactor. Stir and modify it in a water bath for 2 h at a temperature of 60 ° C. After washing to neutrality, dry it at 100 ° C for 12 h.

[0022] b. Prepare 10 mL of 0.28 mol / L copper bromide solution and place it in the reactor (Cu 2+ 2g of the activated carbon prepared in step a was weighed and added into the reactor for immersion for 24h at a temperature of 30°C. The reactor was placed in an oven and dried at 60°C for 8h until the liquid in the reactor disappeared, and then dried at 100°C for 12h;

[0023] c. The activated carbon prepared in step b is placed in a tubular furnace and calcined for 3 hours at a temperature of 300° C. with nitrogen as the inert gas to obtain activated carbon modified by acid and metal complex;

[0024] Example 2

[0025] The difference from Example 1 is that Cu 2+ The loading amount was 11 wt% of activated carbon.

[0026] Example 3

[0027] The difference from Example 1 is that Cu 2+ The loading amount was 13 wt% of activated carbon.

[0028] Example 4

[0029] The original activated carbon was weighed and dried at 100°C for 12 h to obtain an activated carbon adsorbent.

[0030] Example 5

[0031] The difference from Example 1 is that step b is omitted.

[0032] Example 6

[0033] The difference from Example 5 is that the nitric acid in step a is changed to sulfuric acid.

[0034] Example 7

[0035] The difference from Example 5 is that the nitric acid in step a is changed to hydrochloric acid.

[0036] Example 8

[0037] The only difference from Example 2 is that the copper bromide solution in step b is replaced by a ferric bromide solution.

[0038] Example 9

[0039] The only difference from Example 2 is that the copper bromide solution in step b is replaced by a zinc bromide solution.

[0040] Example 10

[0041] Weigh 1 g of the activated carbon adsorbent prepared in Example 1 (dried at 100° C. for 12 h before adsorption) and mix it with a styrene / ethyl sulfide solution with a sulfur content of 2000 ppm in a batch reactor at a solid-liquid ratio of 1:15, and adsorb it for 5 h in a 30°C water bath with shaking conditions. The adsorbed styrene solution is sampled, and the sulfur content in the sample is determined using an ultraviolet fluorescence sulfur analyzer, and the sulfide removal rate is calculated. After adsorption equilibrium, the sulfide removal rate is 26.3%.

[0042] Embodiment 11

[0043] The difference from Example 10 is that the adsorbent is that of Example 2, and the sulfide removal rate is 33.8%.

[0044] Example 12

[0045] The difference from Example 10 is that the adsorbent is that of Example 3, and the sulfide removal rate is 29.8%.

[0046] Embodiment 13

[0047] The difference from Example 10 is that the adsorbent is that of Example 4, and the sulfide removal rate is 3.4%.

[0048] Embodiment 14

[0049] The difference from Example 10 is that the adsorbent is that of Example 5, and the sulfide removal rate is 4.8%.

[0050] Embodiment 15

[0051] The difference from Example 10 is that the adsorbent is that of Example 6, and the sulfide removal rate is 4.2%.

[0052] Example 16

[0053] The difference from Example 10 is that the adsorbent is that of Example 7, and the sulfide removal rate is 3.8%.

[0054] Embodiment 17

[0055] The difference from Example 10 is that the adsorbent is that of Example 8, and the sulfide removal rate is 23.8%.

[0056] Embodiment 18

[0057] The difference from Example 10 is that the adsorbent is that of Example 9, and the sulfide removal rate is 28.6%.

[0058] Figure 1 The desulfurization rates of the embodiments 10, 11, 12 and 13 of the present invention are compared with those of the original activated carbon and the 9wt% Cu 2+ Modified activated carbon, acid pretreatment 11wt% Cu 2+ Modified activated carbon, 13wt% Cu after acid pretreatment 2+ Adsorption effect of modified activated carbon on sulfide, 11wt% Cu after acid pretreatment 2+ The modified activated carbon has the best adsorption effect on sulfide in styrene, and the sulfide removal rate is increased from 3.4% before modification to 33.8%.

[0059] Figure 2The desulfurization rates corresponding to Examples 13, 14, 15 and 16 of the present invention are as follows: + The adsorbents pretreated in three different acid solutions with a concentration of 6.7 mol / L all had better adsorption and desulfurization ether effects than the unmodified adsorbents, but the differences among the three were not significant.

[0060] Figure 3 The adsorption curves of the desulfurized ether of Example 11, Example 17 and Example 18 of the present invention are compared under the same solid-liquid ratio. 2+ Modified activated carbon, acid pretreatment 11wt% Fe 3+ Modified activated carbon, acid pre-treated 11wt% Zn 2+ The adsorption effect of modified activated carbon on sulfide in styrene with a sulfide content of 2000ppm shows that after acid pretreatment, the Cu 2+ The modified activated carbon has the best adsorption effect on sulfide. 2+ The modified activated carbon has the second best adsorption effect on sulfide, Fe 3+ The modified activated carbon has the worst adsorption effect on thioether.

[0061] The above embodiments and descriptions are only for illustrating the principles and best embodiments of the present invention. Without departing from the spirit and scope of the present invention, the present invention may be subject to various changes and improvements, all of which fall within the scope of the present invention to be protected.

Claims

1. A preparation and application method of a modified activated carbon adsorbent for removing sulfide compounds from styrene, wherein the preparation method of the modified activated carbon adsorbent is: The activated carbon and the acid solution are placed in a reaction device, pretreated at 60-80°C for 2-8 hours, washed to neutrality and then dried at 100°C for 12 hours, the pretreated activated carbon and the Cu2+ solution are placed in a reaction device, impregnated and modified at 30°C for 12-24 hours to obtain modified activated carbon, the modified activated carbon is dried at 60-120°C for 2-12 hours, and then the dried activated carbon is placed in a tubular furnace and calcined under inert gas conditions to obtain a modified activated carbon adsorbent.

2. The preparation method according to claim 1, characterized in that: The activated carbon is one or more of coconut shell activated carbon, eucalyptus activated carbon, bamboo activated carbon and rice husk activated carbon.

3. The preparation method according to claim 1, characterized in that: The acid solution is one or more of nitric acid solution, sulfuric acid solution and hydrochloric acid solution, and the H+ concentration in the acid solution is 1-7 mol / L.

4. The preparation method according to claim 1, characterized in that: The proportion of Cu2+ in the activated carbon mass is 0.1wt% to 20wt%.

5. The preparation method according to claim 1, characterized in that: The calcination temperature is 200-400°C, and the calcination time is 2-6 hours.

6. The preparation method according to claim 1, characterized in that: The inert gas is nitrogen or helium.

7. The application method of the modified activated carbon adsorbent is: using styrene solution containing thioether as raw material, adding the raw material and the modified activated carbon obtained by the preparation method of claim 1 into an intermittent reactor for adsorption desulfurization.

8. The use according to claim 7, characterized in that: The modified activated carbon adsorbent needs to be dried before use to remove moisture therein, the drying temperature is 100° C., and the drying time is 12 hours.

9. The use according to claim 7, characterized in that: The reaction adsorption solid-liquid ratio was 1:15, the temperature was 30°C, and the adsorption time was 5 hours.

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