阅读说明：本技术 一种脱除环己醇中环己酮和中间组分的方法 (Method for removing cyclohexanone and intermediate component in cyclohexanol ) 是由 周小文 刘洪武 余卫勋 潘罗其 黎树根 韩娟 鲁华 肖泽威 于 2019-03-06 设计创作，主要内容包括：本发明公开了一种脱除环己醇中环己酮和中间组分的方法,包括以下步骤：1)在一个带侧线采出的粗醇塔之中对酮塔釜液进行精馏,粗醇塔塔顶馏出液返回至粗醇酮槽,侧线采出液进入粗醇槽,粗醇塔釜液排出；2)从粗醇槽中引出粗醇至减压塔中进行减压精馏,减压塔塔顶馏出液进入常压塔中,减压塔釜液返回粗醇槽；3)所述减压塔塔顶馏出液在常压塔中进行常压精馏分离,常压塔塔顶馏出液返回至粗醇槽中,常压塔釜液排出。该方法处理后粗醇中环己酮的含量大幅降低,同时中间组分的含量可以维持在一个较低的范围内,环己醇脱氢转化率大幅提高,并提高了环己醇脱氢的选择性,增加了环己醇脱氢装置的处理能力。(The invention discloses a method for removing cyclohexanone and intermediate components in cyclohexanol, which comprises the following steps: 1) rectifying the ketone tower bottoms in a crude alcohol tower with a side extraction, returning the distillate at the top of the crude alcohol tower to a crude alcohol ketone tank, allowing the side extraction liquid to enter the crude alcohol tank, and discharging the crude alcohol tower bottoms; 2) leading out the crude alcohol from the crude alcohol tank to a vacuum tower for vacuum rectification, leading the distillate at the top of the vacuum tower into an atmospheric tower, and returning the residue of the vacuum tower to the crude alcohol tank; 3) and the distillate at the top of the vacuum tower is subjected to normal-pressure rectification separation in the normal-pressure tower, the distillate at the top of the normal-pressure tower returns to the crude alcohol tank, and the kettle liquid of the normal-pressure tower is discharged. The content of cyclohexanone in the crude alcohol treated by the method is greatly reduced, meanwhile, the content of the intermediate component can be maintained in a lower range, the cyclohexanol dehydrogenation conversion rate is greatly improved, the cyclohexanol dehydrogenation selectivity is improved, and the processing capacity of a cyclohexanol dehydrogenation device is increased.)

1. A method for removing cyclohexanone and intermediate components from cyclohexanol, comprising the steps of:

1) rectifying the ketone tower bottoms in a crude alcohol tower with a side draw, returning the distillate at the top of the crude alcohol tower to a crude alcohol ketone tank, feeding the side draw into the crude alcohol tank, and discharging crude alcohol tower bottoms X oil;

2) leading out the crude alcohol from the crude alcohol tank to a vacuum tower for vacuum rectification, leading the distillate at the top of the vacuum tower into an atmospheric tower, and returning the residue of the vacuum tower to the crude alcohol tank;

3) and the distillate at the top of the vacuum tower is subjected to normal-pressure rectification separation in the normal-pressure tower, the distillate at the top of the normal-pressure tower returns to the crude alcohol tank, and the kettle liquid of the normal-pressure tower is discharged.

2. The method of claim 1, wherein: in the step 1), the crude alcohol tower is a clapboard rectifying tower.

3. The method of claim 1, wherein: the pressure of the top of the crude alcohol tower is 1-10 kPa, and the reflux ratio is 10-100.

4. The method of claim 3, wherein: the distillate at the top of the crude alcohol tower mainly contains cyclohexanone, and the total content of the cyclohexanol and the intermediate components is not higher than 3%; cyclohexanol is mainly used in the side-draw liquid, and the total content of the cyclohexanone and the X oil is not higher than 2%; the crude alcohol tower bottom liquid mainly contains X oil, and the total content of cyclohexanone and cyclohexanol is not higher than 2%.

5. The method of claim 1, wherein: in the step 2), the amount of the crude alcohol material which is led out from the crude alcohol tank and is used for removing the vacuum tower is 1-10 wt% of the side line liquid extraction amount of the crude alcohol tower.

6. The method of claim 1, wherein: in the step 2), the top pressure of the vacuum tower is 1-10 kPa, the reflux ratio is 5-20, the top temperature is 40-100 ℃, and the bottom temperature is 60-120 ℃.

7. The method of claim 6, wherein: the total content of the intermediate components in the distillate at the top of the vacuum tower is not less than 20 percent, and the total content of the intermediate components in the bottom liquid of the vacuum tower is not more than 3 percent.

8. The method of claim 1, wherein: in the step 3), the top pressure of the atmospheric tower is normal pressure, the reflux ratio is 5-20, the top temperature is 150-165 ℃, and the temperature of the tower kettle is 200-220 ℃.

9. The method of claim 8, wherein: in the step 3), the reflux ratio of the atmospheric tower is 10-15, and the temperature of the tower kettle is 205-215 ℃.

10. The method according to claim 8 or 9, characterized in that: the total content of the intermediate components in the distillate at the top of the atmospheric tower is not higher than 3%, and the content of cyclohexanol in the bottom liquid of the atmospheric tower is not higher than 3%.

Technical Field

The invention relates to a method for removing cyclohexanone and intermediate components in cyclohexanol, belonging to the field of cyclohexanone preparation.

Background

Cyclohexanone is produced by oxidation of cyclohexane, typically by the following steps:

(1) oxidizing cyclohexane with molecular oxygen-containing gas to produce cyclohexane oxidizing liquid containing cyclohexyl hydroperoxide, cyclohexanol, cyclohexanone and other matters;

(2) treating cyclohexane oxidation liquid with alkaline solution to decompose cyclohexyl hydroperoxide therein to produce cyclohexanol and cyclohexanone, while neutralizing acid in the oxidation liquid and saponifying ester;

(3) evaporating unreacted cyclohexane for recycling, and feeding the rectification kettle liquid without cyclohexane and a cyclohexanol dehydrogenation product into a crude alcohol ketone tank;

(4) the material extracted from the crude alcohol ketone groove enters a light tower for vacuum rectification, the component which is easier to volatilize than cyclohexanone is separated from the top of the tower, and the cyclohexanone, the cyclohexanol and the component which is harder to volatilize than cyclohexanone are discharged from the bottom of the tower;

(5) the material in the light tower bottom enters a ketone tower for vacuum rectification, the product cyclohexanone is obtained from the tower top, and cyclohexanol and components which are more difficult to volatilize than cyclohexanone are discharged from the tower bottom;

(6) the ketone tower bottom liquid enters an alcohol tower for vacuum rectification, the component which is more volatile than cyclohexanol is distilled out from the top of the tower together with the cyclohexanol, the distilled component is sent to a crude alcohol tank, and the component which is less volatile than the cyclohexanol is discharged from the tower bottom;

(7) and (3) leading out the material from the crude alcohol tank to a cyclohexanol dehydrogenation process, wherein part of cyclohexanol is dehydrogenated into cyclohexanone, and a dehydrogenation product is led into the crude alcohol ketone tank and is used as a raw material of the light tower together with the bottom liquid of the alkane tower.

As can be seen from the above typical process for cyclohexanone production, substances produced from cyclohexane oxidation and cyclohexanol dehydrogenation and having volatility between cyclohexanone and cyclohexanol under the operating conditions of the respective rectification columns cannot be removed from the rectification process, and are gradually accumulated in the rectification system, which affects cyclohexanone production, and these substances are collectively referred to as intermediate components.

These volatility components in the intermediate between cyclohexanone and cyclohexanol are mostly impurities with a higher boiling point than cyclohexanol at atmospheric pressure, which distill together with cyclohexanol from the top of the column due to azeotropy with cyclohexanol under column rectification conditions, resulting in a gradual increase in the content of the intermediate components in the crude alcohol tank feed, often exceeding 10% in total. In the existing method, when a device is overhauled or stopped, a component with higher content of an intermediate component in a crude alcohol ketone tank and a crude alcohol tank is treated as a waste material, and the content of the intermediate component in a rectification material is gradually increased after normal driving. These intermediate components, when present in high amounts, can adversely affect cyclohexanone production: firstly, the substances are evaporated in an alcohol tower, energy is consumed, then the substances enter a cyclohexanol dehydrogenation process along with cyclohexanol, return to a crude alcohol ketone tank after evaporation, temperature rise, reaction and temperature reduction, and enter a light tower, a ketone tower and the alcohol tower again, so that ineffective circulation of the materials is caused, the energy consumption is increased, and the equipment space is occupied by extrusion; secondly, when the content of the impurities is high, a small amount of the impurities enter a cyclohexanone product at the top of the ketone tower, so that the quality of the cyclohexanone is reduced; thirdly, in order to ensure the quality of the cyclohexanone, the content of the cyclohexanone in the material in the ketone tower bottom has to be increased, so that excessive cyclohexanone is brought into the cyclohexanol dehydrogenation raw material, the conversion rate of the cyclohexanol in the dehydrogenation process is reduced, the condensation side reaction of the cyclohexanone is increased, and the selectivity of cyclohexanol dehydrogenation is reduced; and fourthly, the crude alcohol ketone material with higher content of the intermediate components and the crude alcohol material are treated as waste materials during the parking period, so that the material consumption of cyclohexanone production is increased.

The amount of the intermediate components produced is small, and in the case of a 10 ten thousand ton/year cyclohexanone device, the amount of the intermediate components produced is about 40 tons/year, and 5kg/h, so that the concentration of the intermediate components in the rectification system can be kept constant only by removing the intermediate components at a rate of 5 kg/h.

Wushohui, petrochemical 1983,12(10):642-649, states that the impurities contained in cyclohexanol increase the thermal instability of cyclohexanol itself, and that the high-boiling-point content increases by 3-4% when 90-91% of industrially rectified cyclohexanol is passed through a superheater, while almost no change occurs when 98-98.8% of cyclohexanol is used. When industrially rectified cyclohexanol is used, the dehydrogenation selectivity is reduced by about 4% as compared with pure cyclohexanol, so that the cyclohexanol dehydrogenation feed should be refined to minimize the impurity content of cyclohexanol, for example, by adding a cutting column to the rectification system of ketone alcohol, but no specific method is given.

Chinese patent 201620707871.1 discloses a device for removing impurities in butyl cyclohexyl ether in the production process of cyclohexanone, which is to add a rectifying tower behind a cyclohexanol evaporator to carry out normal pressure or pressure rectification on crude cyclohexanol, and discharge part of butyl cyclohexyl ether from the tower bottom to a recombination separation tank, thereby achieving the purpose of reducing the content of intermediate components in the crude cyclohexanol. But the content of the butyl cyclohexyl ether in the discharged tower bottom liquid is only 25-35%, and the rest of the components are cyclohexanol, which means that cyclohexanol which is 2-3 times of the butyl cyclohexyl ether is treated as a byproduct, and the material consumption is increased. In addition, the problem of too high a content of cyclohexanone in the crude cyclohexanol still remains.

Chinese patent 201610837394.5 discloses a process for preparing cyclohexanone by cyclohexanol dehydrogenation, wherein the equipment of the cyclohexanol dehydrogenation process consists of a cyclohexanol evaporator, a vapor-liquid separator, a normal-pressure or pressurized rectifying tower and a cyclohexanol dehydrogenation reactor; the rectifying tower is only provided with a stripping section, and the tower kettle is provided with a reboiler. The process can greatly reduce the concentration of the methylcyclohexanone, the heptanone and the analogues thereof contained in the materials of the cyclohexanone rectification process and the cyclohexanol dehydrogenation process, and reduce the circulation and accumulation of the methylcyclohexanone, the heptanone and the analogues thereof in the cyclohexanone rectification process and the cyclohexanol dehydrogenation process. However, the process can not reduce the content of cyclohexanone in the cyclohexanol raw material, and the material discharged from the tower still contains about 30% of cyclohexanol, so that the material consumption is increased. In addition, the removal of these impurities from the column bottom at very low levels under atmospheric or pressurized conditions requires high energy consumption.

The common point of the patents is that the intermediate components are removed from the tower bottom only by normal pressure or pressure rectification, and under the condition that the content of the intermediate components in the raw materials is not high, the impurities are removed from the tower bottom, and more energy is consumed, for example, when the material containing 90 percent of cyclohexanol and 10 percent of intermediate components is rectified under normal pressure or pressure, the reflux ratio is set to be 4, and at least 45 parts of cyclohexanol is required to be evaporated when 1 part of the intermediate components is removed; if the reflux ratio is 4 during the normal pressure or pressurized rectification of the material containing 96% cyclohexanol and 4% intermediate component, at least 120 parts of cyclohexanol need to be evaporated every 1 part of intermediate component is removed, and the energy consumption is increased sharply.

Meanwhile, cyclohexanol dehydrogenation is an endothermic equilibrium reaction, and increasing the concentration of cyclohexanone in the raw material can shift the equilibrium towards the raw material direction, so that the productivity of cyclohexanol dehydrogenation is reduced, and therefore, the concentration of cyclohexanone in the raw material should be reduced as much as possible. Limited by the separation capacity of the intermediate product and the ketone tower, in order to ensure the quality of cyclohexanone as a ketone top product, the concentration of cyclohexanone in the material in the bottom of the ketone tower is often controlled to be more than 4%, sometimes as high as 8%, even as high as 10%, so that the cyclohexanone in the material in the bottom of the ketone tower needs to be separated.

Disclosure of Invention

The invention aims to provide a method for removing cyclohexanone and intermediate components in cyclohexanol, aiming at solving the problem that the cyclohexanol dehydrogenation capacity is low due to the fact that the content of cyclohexanone and intermediate components in crude cyclohexanol is too high in the existing industrial production device.

In order to achieve the above object, the present invention provides a method for removing cyclohexanone and intermediate components from cyclohexanol, comprising the steps of:

1) rectifying the ketone tower bottoms in a crude alcohol tower with a side draw, returning the distillate at the top of the crude alcohol tower to a crude alcohol ketone tank, feeding the side draw into the crude alcohol tank, and discharging crude alcohol tower bottoms X oil;

2) leading out the crude alcohol from the crude alcohol tank to a vacuum tower for vacuum rectification, leading the distillate at the top of the vacuum tower into an atmospheric tower, and returning the residue of the vacuum tower to the crude alcohol tank;

3) and the distillate at the top of the vacuum tower is subjected to normal-pressure rectification separation in the normal-pressure tower, the distillate at the top of the normal-pressure tower returns to the crude alcohol tank, and the kettle liquid of the normal-pressure tower is discharged.

Preferably, in the step 1), the crude alcohol tower is a baffle distillation tower. The partition is positioned in the middle of the crude alcohol tower, is vertically arranged and divides the crude alcohol tower into four areas, the upper part of the partition is a public rectification section, the left side of the partition is a feeding section, the right side of the partition is a lateral line extraction section, and the lower part of the partition is a public stripping section.

The invention preferably adopts the clapboard rectifying tower, saves equipment investment and energy consumption, and can better separate the tower top distillate, the side-draw liquid and the tower bottom liquid, thereby better achieving the purpose of impurity removal and purification.

Preferably, in the step 1), the pressure at the top of the crude alcohol tower is 1-10 kPa, and preferably 2-4 kPa; the reflux ratio is 10 to 100, preferably 30 to 60.

More preferably, the distillate at the top of the crude alcohol tower mainly contains cyclohexanone, and the total content of the cyclohexanol and the intermediate components is not higher than 3 wt%; cyclohexanol is mainly used in the side-draw liquid, and the total content of the cyclohexanone and the X oil is not higher than 2 wt%; the crude alcohol tower bottom liquid mainly contains X oil, and the total content of cyclohexanone and cyclohexanol is not higher than 2 wt%.

Preferably, in the step 2), the amount of the crude alcohol material discharged from the crude alcohol tank to the vacuum tower is 1 to 10 wt%, preferably 1 to 5 wt% of the side-line liquid amount of the crude alcohol tower.

Preferably, in the step 2), the tower top pressure of the decompression tower is 1-10 kPa, and preferably 1-5 kPa; the reflux ratio is 5-20, preferably 10-15; the temperature at the top of the tower is 40-100 ℃, and preferably 40-60 ℃; the temperature of the tower kettle is 60-120 ℃, and preferably 60-100 ℃.

More preferably, the total content of the intermediate components in the distillate at the top of the vacuum column is not less than 20% by weight, and the total content of the intermediate components in the bottom liquid of the vacuum column is not more than 3% by weight.

Preferably, in the step 3), the top pressure of the atmospheric tower is normal pressure, the reflux ratio is 5-20, and preferably 10-15; the temperature at the top of the tower is 150-165 ℃, and preferably 155-162 ℃; the temperature of the tower kettle is 200-220 ℃, and preferably 205-215 ℃.

More preferably, the total content of the intermediate components in the atmospheric tower overhead distillate is not more than 3 wt%, and the cyclohexanol content in the atmospheric tower bottoms is not more than 3 wt%.

Compared with the prior art, the technical scheme of the invention has the beneficial technical effects that:

1) according to the technical scheme of the invention, the content of cyclohexanone in crude alcohol can be greatly reduced to below 1 wt%, and the condensation side reaction speed caused by cyclohexanone in the temperature rising process of dehydrogenation raw materials is greatly reduced.

2) According to the technical scheme of the invention, the content of the intermediate components in the crude alcohol can be gradually reduced and finally maintained in a lower content range, and the material composition in the rectification process and the cyclohexanol dehydrogenation process tends to be stable, thereby being beneficial to the stable operation of the device.

3) According to the technical scheme of the invention, the content of cyclohexanone in crude alcohol is greatly reduced, meanwhile, the content of intermediate components can be maintained in a lower range, the cyclohexanol content in the cyclohexanol dehydrogenation raw material is higher, the cyclohexanol dehydrogenation conversion rate is greatly improved, the processing capacity of a cyclohexanol dehydrogenation device is increased, and the cyclohexanol dehydrogenation selectivity is improved.

4) According to the technical scheme of the invention, the content of cyclohexanone and intermediate components in the crude alcohol is low, so that the caused ineffective evaporation and the heat loss thereof in the processes of temperature rise and temperature drop are reduced, and the energy consumption is reduced.

5) According to the technical scheme of the invention, by utilizing the characteristic that the intermediate component and cyclohexanol are subjected to azeotropic distillation in a certain vacuum range, the intermediate component is subjected to vacuum concentration to be more than 20 wt% and then subjected to normal-pressure rectification, compared with the direct normal-pressure or pressurized rectification of a crude cyclohexanol solution, a large amount of cyclohexanol is not required to be evaporated, the handling capacity of a normal-pressure tower is greatly reduced, the energy consumption is greatly reduced, meanwhile, the content of cyclohexanol in high-boiling-point impurities discharged from a normal-pressure tower kettle is also greatly reduced, the material consumption is also reduced, and particularly, when the content of the intermediate component in a dehydrogenation raw material is lower, the energy consumption of the method can be greatly reduced.

Drawings

FIG. 1 is a schematic process flow diagram of the present invention;

wherein: 1.11, ketone tower bottom liquid, 12, crude alcohol tower top distillate, 13, side draw liquid, 14, crude alcohol tower bottom liquid, 2, a crude alcohol tank, 21, a material of cyclohexanol dehydrogenation process, 22, a crude alcohol material of a decompression tower, 3, a decompression tower, 31, decompression tower top distillate, 32, decompression tower bottom liquid, 4, an atmospheric tower, 41, atmospheric tower top distillate, 42 and atmospheric tower bottom liquid.

Detailed Description

The following examples are intended to further illustrate the present disclosure in conjunction with the accompanying drawings and not to limit the scope of the claims of the present disclosure.

In the embodiment of the invention, the diameter of a crude alcohol tower 1 is 3.6m, 250Y fillers are filled in the crude alcohol tower, a partition plate is arranged in the crude alcohol tower or not arranged in the crude alcohol tower, when the partition plate is arranged, the whole crude alcohol tower is divided into 4 areas, the upper part of the partition plate is a common rectification section, the height of the fillers is 12m, the left side of the partition plate is a feeding section, the upper and lower parts of the partition plate are respectively filled with 6m fillers, the right side of the partition plate is a side line extraction section, the upper and lower parts of the partition plate are respectively filled with 6m fillers, the lower part of the partition plate is a common stripping section. The diameter of the vacuum tower 3 is 1.0m, 250Y fillers are filled in the tower, the total height of the fillers is 32m, the vacuum tower is divided into an upper section and a lower section, the heights of the fillers are 18m and 14m in sequence, and the feeding materials are positioned between the two sections of fillers. The diameter of the atmospheric tower 4 is 0.3m, 250Y fillers are filled in the tower, the total height of the fillers is 24m, the tower is divided into an upper section and a lower section, the heights of the fillers are 10m and 14m in sequence, and the feeding materials are positioned between the two sections of the fillers.

Unless otherwise specified, the percentages in the following embodiments are by mass.