CN102718621A - Method for selectively desorbing carbon disulfide in coarse benzene - Google Patents

Abstract

The invention discloses a method for selectively adsorbing and removing carbon disulfide in crude benzene. The method uses silica-alumina molecular sieve as an adsorbent to directly and selectively adsorb carbon disulfide in crude benzene under the condition of 10-60 DEG C and normal pressure. Moreover, after the adsorption is saturated, the adsorbent can be regenerated and reused after being purged with _N2 at 200-400°C for 2-6 hours, and at the same time, the carbon disulfide after adsorption and removal can be desorbed and recycled. The invention has the advantages of mild adsorption conditions, simple equipment, easy operation, high selective adsorption, and the regenerated adsorbent can be recycled and the like.

Description

A method for selective adsorption and removal of carbon disulfide in crude benzene

technical field

The invention belongs to the technical field of coal chemical industry and relates to the impurity removal of crude benzene recovered from coke oven gas. More specifically, the invention provides a method for selectively adsorbing and removing carbon disulfide in crude benzene by using silicon-aluminum molecular sieves.

Background technique

Carbon disulfide, as an organic sulfur impurity contained in crude benzene, has a mass fraction of about 0.3-0.4%. It will corrode equipment and pollute the environment due to its slow hydrolysis in the process of chemical product production and conversion, which will also cause poisoning of some industrial catalysts and affect industrial production. In the crude benzene refining process of the coking plant, carbon disulfide in the crude benzene is firstly removed, which can improve the organic sulfur hydrogenation treatment capacity in the crude benzene refining process, thereby increasing the output and purity of the crude benzene refined products, and increasing the economics of the plant benefit. Therefore, the removal of carbon disulfide is very important for reducing industrial production losses and improving the quality of chemical products.

At present, there are adsorption and chemical methods for removing carbon disulfide. The chemical method has high energy consumption, complicated operation, high cost, and destroys the structure of carbon disulfide, so it cannot be recycled. The adsorption method is simple, easy to operate, low in energy consumption, and good in removal effect. It is a non-destructive method and can realize the recovery and utilization of carbon disulfide at the same time.

Publication number is that the patent application of CN 1846847 A discloses a kind of active carbon fiber adsorption material, and this material can be used for adsorption and removes carbon disulfide in the air. The patent application with publication number CN 102295953 A discloses a method for removing carbon disulfide, which converts carbon disulfide into xanthate, and then separates xanthate by distillation or rectification. However, this method has a cumbersome process and relatively high energy consumption, and carbon disulfide cannot be recycled.

So far, there is no report on the use of silica-alumina molecular sieve as an adsorbent for adsorption and removal of carbon disulfide in crude benzene.

Contents of the invention

Aiming at the deficiencies in the prior art, the object of the present invention is to provide a method for selectively adsorbing and removing carbon disulfide in crude benzene, which uses silica-alumina molecular sieves as the adsorbent.

In order to achieve the above object, the present invention provides a method for selectively adsorbing and removing carbon disulfide in crude benzene, the method comprising: step a) using silica-alumina molecular sieve as an adsorbent, and allowing crude benzene to pass through the silica-alumina molecular sieve for adsorption Remove carbon disulfide from crude benzene.

Wherein, the method for selectively adsorbing and removing carbon disulfide in crude benzene provided by the present invention may further include: step b) after the silica-alumina molecular sieve is saturated in adsorption, blowing _N2 to regenerate the silica-alumina molecular sieve.

The above steps a) and b) can be carried out cyclically.

Wherein, the method for selective adsorption and removal of carbon disulfide in crude benzene provided by the present invention may further include: step c) condensing and recovering carbon disulfide in N ₂ (the gas is a mixed gas carrying carbon disulfide) after purging in step b); .

Wherein, the silica-alumina molecular sieve in step a) can be selected from 4A type, 5A type, 13X type, 10X type, sodium Y type and calcium Y type. The above-mentioned silica-alumina molecular sieves are all alkali metal aluminosilicates, mainly composed of silica and alumina. The pore distribution is uniform, the pore size is between 0.4-1.0nm, and the specific surface area is 300-1000m ² /g, has a strong adsorption function. Those skilled in the art can select a suitable type of silica-alumina molecular sieve according to actual needs.

The removal described in step a) can be carried out under normal pressure conditions, the removal temperature is 10-60°C, and the space velocity ratio is 0.4-2.0h ^-1 (mass flow rate of crude benzene/mass of adsorbent).

The conditions for purging with N ₂ in step b) are: after heating to 200-400° C. within 2-3 hours, purging for 2-6 hours.

The effects and benefits of the present invention are: in the method for adsorption and removal of carbon disulfide in crude benzene provided by the present invention, silicon-aluminum molecular sieves are used as the adsorbent for the first time, which has a large adsorption capacity for carbon disulfide in crude benzene and a high selective adsorption removal rate. The deep removal of carbon disulfide can be realized, and the carbon disulfide after adsorption and removal can be recycled. In this way, it not only reduces the energy consumption required for organic sulfur hydrogenation in the crude benzene refining process of the factory in the prior art, but also improves the output and purity of crude benzene refined products, simplifies the operation process, reduces maintenance costs, and increases the economic benefits of the plant . In addition, compared with the conventional method for removing carbon disulfide, the silica-alumina molecular sieve adsorbent used in the method of the present invention is convenient and easy to obtain, the adsorption operation conditions are mild, the operation is convenient, and the cost is greatly reduced. Moreover, the adsorbent is easy to regenerate, and after regeneration, it still has a high adsorption effect on carbon disulfide in benzene, and the adsorbent has a long service life.

Detailed ways

The specific implementation manner of the present invention will be described in detail below in conjunction with the technical solutions.

Example 1

Removal of carbon disulfide:

Dissolve carbon disulfide in pure benzene to make simulated crude benzene, so that the concentration of carbon disulfide in simulated crude benzene is 3000mg/kg. 200g of 5A type 5A silica-alumina molecular sieve (Nankai University Catalyst Factory) was fixed in the adsorber. Under normal temperature and pressure, the space velocity ratio was 0.7h ^-1 , and the simulated crude benzene was introduced. The reaction result was that the adsorption and removal rate of carbon disulfide was 100%. %.

Recovery of carbon disulfide:

After the adsorption and saturation of the 5A-type silica-alumina molecular sieve adsorbent is saturated, it is purged with N ₂ , the temperature is raised to 300°C within 2 hours, and the temperature is maintained at 300°C for 3 hours for the first regeneration. The 5A type after the first regeneration The silica-alumina molecular sieve is designated as sample I. After the purged N ₂ is condensed by the condenser, the carbon disulfide in it is condensed and recovered, and the condensate is denoted as A ₁ .

Use the sample I regenerated for the first time to remove carbon disulfide from crude benzene according to the above method, and treat sample I according to the above regeneration method, and record the 5A silica-alumina molecular sieve after the second regeneration as sample II. The 5A-type silica-alumina molecular sieve can be recycled. The results of the carbon disulfide removal rate of the 5th cycle are recorded in Table 1, and the analysis results of the carbon disulfide concentration in the condensate used for 5 cycles are respectively recorded in Table 2.

Example 2

Removal of carbon disulfide:

Dissolve carbon disulfide in pure benzene to make simulated crude benzene, so that the concentration of carbon disulfide in simulated crude benzene is 3000mg/kg. 200g of sodium Y-type silica-alumina molecular sieve (Nankai University Catalyst Factory) was fixed in the adsorber, under normal temperature and pressure, the space velocity ratio was 0.7h ^-1 , and the simulated crude benzene was introduced. The reaction result was that the adsorption and removal rate of carbon disulfide was 100%.

Recovery of carbon disulfide:

After the sodium Y-type silica-alumina molecular sieve adsorbent is adsorbed and saturated, it is purged with N ₂ , and the temperature is raised to 300°C within 2 hours, and maintained at 300°C for 3 hours for the first regeneration, and the sodium after the first regeneration The Y-type silica-alumina molecular sieve is designated as sample III. After the purged N ₂ is condensed by the condenser, the carbon disulfide in it is condensed and recovered, and the condensate is denoted as B ₁ .

Use the sample III regenerated for the first time to remove carbon disulfide from crude benzene according to the above method, and treat sample III according to the above regeneration method, and record the sodium Y-type silica-alumina molecular sieve after the second regeneration as sample IV. Sodium Y-type silica-alumina molecular sieve can be recycled. The results of the removal rate of carbon disulfide for 5 cycles are recorded in Table 1, and the analysis results of carbon disulfide concentration in the condensate used for 5 cycles are respectively recorded in Table 2.

Example 3

Removal of carbon disulfide:

Dissolve carbon disulfide in pure benzene to make simulated crude benzene, so that the concentration of carbon disulfide in simulated crude benzene is 3000mg/kg. 200g of 13X type 13X silica-alumina molecular sieve (Nankai University Catalyst Factory) was fixed in the adsorber. Under normal temperature and pressure, the space velocity ratio was 0.7h ^-1 , and simulated crude benzene was introduced. The reaction result was that the adsorption and removal rate of carbon disulfide was 100%. %.

Recovery of carbon disulfide:

After the adsorption and saturation of the 13X-type silica-alumina molecular sieve adsorbent is saturated, it is purged with N ₂ , the temperature is raised to 300°C within 2 hours, and the first regeneration is performed at 300°C for 3 hours. The silica-alumina molecular sieve is designated as sample VI. After the purged N ₂ is condensed by the condenser, the carbon disulfide in it is condensed and recovered, and the condensate is recorded as C ₁ .

Use sample VI after the first regeneration to remove carbon disulfide from crude benzene according to the above method, and treat sample VI according to the above regeneration method, and record the 13X type silica-alumina molecular sieve after the second regeneration as sample VII. The 13X-type silica-alumina molecular sieve can be recycled. The results of the removal rate of carbon disulfide for 5 cycles are recorded in Table 1, and the analysis results of carbon disulfide concentration in the condensate used for 5 cycles are respectively recorded in Table 2.

Table 1 Experimental results of cyclic adsorption of different silica-alumina molecular sieves

Table 2 Concentration of carbon disulfide in the condensate after regeneration and desorption _of N by different silica-alumina molecular sieves

As can be seen from Table 1 and Table 2, the silica-alumina molecular sieve used in the present invention is used as an adsorbent, and the removal rate of carbon disulfide can reach 100%. In addition, the regenerated silica-alumina molecular sieve still has a high adsorption performance on carbon disulfide. For example, the removal rate of carbon disulfide is over 93% after 3 cycles of use, and can still reach over 82% after 5 cycles of use. Among them, the 5A type Molecular sieves have the best adsorption capacity for carbon disulfide.

Claims (7)

1. A method for selective adsorption and removal of carbon disulfide in crude benzene, characterized in that the method comprises: step a) using silicon-aluminum molecular sieves as the adsorbent, and making crude benzene pass through the silicon-aluminum molecular sieves to adsorb and remove crude benzene Carbon disulfide in benzene. 2 . The method according to claim 1 , further comprising: step b) after the silica-alumina molecular sieve is adsorbed and saturated, injecting N ₂ for purging to regenerate the silica-alumina molecular sieve. 3 . 3. The method according to claim 1 or 2, characterized in that said steps a) and b) are carried out cyclically. 4. The method according to claim 1 or 2, characterized in that the method further comprises: step c) condensing and recovering the carbon disulfide in the _N2 purged in step b). 5. The method according to claim 1 or 2, characterized in that the silicon-aluminum molecule in step a) is selected from 4A type, 5A type, 13X type, 10X type, sodium Y type and calcium Y type. 6. The method according to claim 1 or 2, characterized in that the removal described in step a) is carried out under normal pressure conditions, the removal temperature is 10-60°C, and the space velocity ratio is 0.4-2.0h ^-1 . 7. The method according to claim 1 or 2, characterized in that the conditions for purging with N ₂ in step b) are: after heating to 200-400°C within 2 to 3 hours, purging for 2- 6 hours.