CN110437117B

CN110437117B - Method for preparing cumene hydroperoxide by oxidizing cumene

Info

Publication number: CN110437117B
Application number: CN201910850055.4A
Authority: CN
Inventors: 朱发明; 刘鹏; 崔娇英; 代红涛; 员玫; 孙犀璨; 陈晨; 乔小飞
Original assignee: Wanhua Chemical Group Co Ltd; Wanhua Chemical Ningbo Co Ltd
Current assignee: Wanhua Chemical Group Co Ltd; Wanhua Chemical Ningbo Co Ltd
Priority date: 2019-09-10
Filing date: 2019-09-10
Publication date: 2021-07-23
Anticipated expiration: 2039-09-10
Also published as: CN110437117A

Abstract

The invention relates to a method for preparing cumene hydroperoxide by oxidizing cumene. The method comprises the following steps: cumene hydroperoxide is produced by oxidation of cumene in the presence of alpha-methylstyrene dimer. Preferably, the process is also carried out in the presence of a by-product inhibitor. When the reaction liquid contains a certain amount of alpha-methylstyrene dimer, the conversion rate of the cumene is improved, and after the alpha-methylstyrene dimer and the byproduct inhibitor are added simultaneously, the conversion rate of the cumene can be increased and the selectivity of the methyl phenyl ketone can be effectively reduced.

Description

Method for preparing cumene hydroperoxide by oxidizing cumene

Technical Field

The invention relates to a method for oxidizing cumene into cumene hydroperoxide by liquid phase, in particular to a method for controlling by-products in the production process of the cumene hydroperoxide

Background

Cumene hydroperoxide can be prepared by the liquid phase oxidation of cumene with an oxygen containing gas such as air. Such oxidation methods are well known in the art.

In such cumene oxidation reactions, dimethylbenzyl alcohol (DMBA) and methyl phenyl ketone (PMK) are formed as by-products. Subsequent oxidation of propylene with the cumene hydroperoxide results in the production of Propylene Oxide (PO) and dimethylbenzyl alcohol (DMBA). Dimethyl benzyl alcohol can be converted into isopropyl benzene again through hydrogenolysis reaction with hydrogen to be used as raw materials of oxidation reaction for recycling.

In such a process, the production of propylene oxide co-products is avoided and only propylene oxide products of greater market value are produced.

The process described for the production of Propylene Oxide (PO) is generally referred to as the CHP/PO process. Typically the CHP/PO process comprises the following steps: contacting cumene with air and oxidizing to produce Cumene Hydroperoxide (CHP); CHP oxidizes propylene to propylene oxide, which itself is reduced to dimethylbenzyl alcohol; ③ the dimethyl benzyl alcohol and hydrogen are subjected to hydrogenolysis reaction to generate the isopropyl benzene.

In the step (i), CHP is further subjected to a series side reaction while cumene is oxidized to generate CHP, so that the CHP selectivity is reduced, and therefore, the conversion per pass of cumene in an industrial process is generally lower than 30 wt%.

Thus, the concentration of cumene hydroperoxide in the reaction mixture is kept relatively low. It is always desirable in the art to achieve higher oxidation rates when operating at the above maximum cumene hydroperoxide concentrations. Chinese patent CN201210429266.9 discloses a method for increasing cumene conversion rate, which uses non-metallic solid carbon catalyst, and is environment-friendly and cheap, but cumene hydroperoxide selectivity is not high.

Meanwhile, the prior process technology and scheme do not mention a method for specifically inhibiting a certain byproduct, such as a byproduct methyl phenyl ketone (PMK). From the standpoint of atom economy, dimethylbenzyl alcohol (DMBA) can be returned to the original cumene by dehydration hydrogenation, while methylphenylketone is converted to a by-product which is economically undesirable.

Disclosure of Invention

The invention provides a method for preparing cumene hydroperoxide by oxidizing cumene. The addition of alpha-methylstyrene dimer to cumene enables a specific cumene conversion to be achieved in a shorter period of time. And a byproduct inhibitor can be added at the same time, so that the oxidation reaction speed of the cumene can be remarkably accelerated, and the selectivity of the methyl phenyl ketone with poor economy can be effectively reduced.

In order to solve the technical problems, the invention provides the following technical scheme:

a method for preparing cumene hydroperoxide by cumene oxidation comprises the following steps: cumene hydroperoxide is produced by oxidation of cumene in the presence of alpha-methylstyrene dimer.

In the method of the present invention, the α -methylstyrene dimer includes, but is not limited to, one or more of 2, 4-diphenyl-4-methyl-1-pentene, 2, 4-diphenyl-4-methyl-2-pentene, 1, 2-trimethyl-3-phenylindane, cis-1, 3-dimethyl-1, 3-diphenylcyclobutane, or trans-1, 3-dimethyl-1, 3-diphenylcyclobutane.

In the process of the present invention, the amount of alpha-methylstyrene dimer should be such that the amount of alpha-methylstyrene dimer in the reaction mixture is a promoting amount. More specifically, the amount should preferably be such that a specific cumene conversion is achieved in a shorter period of time than in the case where no α -methylstyrene dimer is added.

In the process of the present invention, the concentration of the α -methylstyrene dimer is from 0.001 to 1.0% by weight, preferably from 0.002 to 0.5% by weight, more preferably from 0.003 to 0.3% by weight, based on the total weight of the reaction liquid-phase mixture.

As a preferred embodiment, the method of the present invention may also be performed in the presence of a byproduct inhibitor, the byproduct inhibitor comprising an active component and a carrier, wherein the active component is an element in group VIIB or VIII, preferably one or more of cobalt, manganese, and iron. The carrier is selected from one or more oxides or carbonates of elements in IIA, IIIA and IVA groups of the periodic table of elements, preferably one or more of alumina, silica and magnesia.

The content of active component metal elements in the byproduct inhibitor is 0.01-50% of the total weight of the byproduct inhibitor, and the carrier is 50-99.99%.

The preparation method of the byproduct inhibitor comprises the following steps: (1) adding the carrier into a metal salt aqueous solution with the concentration of the active component metal element of 1-40 wt%, and stirring for 0.5-24h at 25-100 ℃; (2) adding a precipitant solution with the concentration of 1-40 wt% into the mixture obtained in the step (1), and stirring for 0.5-50h at the temperature of 25-100 ℃; (3) filtering the mixture obtained in the step (2), drying the filter cake at 25-180 ℃, and then reducing for 1-20h under the hydrogen atmosphere at 300-700 ℃ to obtain the byproduct inhibitor.

The metal salt of the active component of the byproduct inhibitor is selected from one or more of nitrate, sulfate, chloride or acetate.

The precipitator in the preparation method of the byproduct inhibitor is selected from any one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, ammonium carbonate, ammonia water and urea; the molar ratio of the precipitant to the metal salt is 0.5-5: 1.

the weight ratio of the byproduct inhibitor to the reaction liquid phase mixture is 0.0001-0.05: 1, preferably 0.006-0.012: 1.

In the method of the present invention, the oxidizing agent used in the oxidation reaction is an oxygen-containing gas.

In the process of the present invention the oxidation of cumene to cumene hydroperoxide is carried out at a temperature of from 20 to 200 c, suitably from 50 to 150 c, more suitably from 60 to 120 c.

In the process according to the invention, the pressure of the oxidation reaction is not critical and can be chosen to best suit the particular situation. In general, the reaction pressure is from atmospheric pressure to 1MPaG, preferably from 0.05 to 0.5 MPaG.

In the process according to the invention, the gas removed via the one or more gas outlets of the oxidation reactor may contain a certain amount of cumene vapour. If desired, the cumene vapor can be condensed to a liquid and recycled.

The oxidation is carried out by feeding an oxygen-containing gas as a gaseous inlet material to the reaction mixture. The oxygen concentration in the gas feed may be in the range 5 to 100 vol%, suitably 10 to 60 vol%, more suitably 20 to 50 vol%, with the remainder preferably being an inert gas, for example nitrogen. Air containing on average 21 vol% oxygen is the preferred oxygen-containing gas feed. The temperature of the gas at the gas inlet may be from ambient temperature to 200 ℃.

The separation method of the by-product inhibitor from the reaction solution may be any of conventional solid-liquid separation methods such as filtration, centrifugation and adsorption, and the separation method by filtration is particularly preferred.

The alpha-methylstyrene dimer and the reaction solution may be separated by a common process such as rectification, extraction, etc., and preferably by a rectification process.

The alpha-methyl styrene dimer can react with free radicals and then transfer to cumene on one hand, so that the yield of the cumene hydroperoxide is improved; on the other hand, the decomposition of cumene hydroperoxide to generate alpha-methyl styrene is an equilibrium reaction, and the reversible reaction decomposition of dimer thereof to generate alpha-methyl styrene inhibits the equilibrium reaction from moving rightwards to a certain extent.

When the alpha-methylstyrene dimer and the byproduct inhibitor are added simultaneously, it is presumed that the active component in the byproduct inhibitor, the alpha-methylstyrene dimer and the cumene hydroperoxide form a similar complex form, so that the stability of the cumene hydroperoxide is enhanced, the decomposition of the cumene hydroperoxide is inhibited, and the selectivity of the methyl phenyl ketone is effectively reduced while the conversion rate of the cumene is increased.

By the process, in the process of oxidizing cumene into cumene hydroperoxide by using the cumene, the content of alpha-methyl styrene dimer is controlled, and the inhibitor containing metal elements is added, so that the oxidation reaction speed of the cumene can be remarkably accelerated, the composition of methyl phenyl ketone with poor economy can be effectively reduced, the process atom economy is good, and the byproducts are few.

Detailed Description

The analysis method comprises the following steps:

for dimethylbenzyl alcohol (DMBA) and methylphenyl ketone (PMK), measurements were made by gas chromatography.

The gas chromatographic analysis conditions were:

an analytical instrument: GC1690 gas chromatograph;

data recording and processing: FL9500 chromatography workstation;

a chromatographic column: SE-54 polar capillary column, 30 m;

internal standard substance: mesitylene; sample solvent: methanol

Column temperature: 120 ℃; the gasification temperature: 220 deg.C

A detector: hydrogen Flame Ion Detector (FID), 220 deg.C

Sample introduction amount: 0.2 mu L; carrier gas: high purity nitrogen gas, 80ml/min

The split ratio is as follows: 60: 1; analysis duration: 8min

Measuring Cumene Hydroperoxide (CHP) by an indirect iodometry, accurately weighing a certain sample in a conical flask, adding glacial acetic acid with the same volume and saturated potassium iodide solution, heating and stirring at 60 ℃ for 5min, then titrating to light yellow by using a sodium thiosulfate standard solution, adding 2 drops of a starch indicator, and continuously titrating until blue disappears, thus obtaining the end point. According to the same steps, a blank experiment is carried out on the solution without the sample.

The process of the present invention is illustrated in more detail by the following non-limiting examples.

Synthesis of byproduct inhibitor 1:

preparation of Co-MgO byproduct inhibitor: 20g of cobalt acetate was dissolved in 180mL of distilled water to prepare a 10 wt% aqueous solution of cobalt acetate. Then, 27g of magnesium oxide powder was added to the above aqueous cobalt acetate solution under stirring at 25 ℃ and stirred for 18 hours. Preparing a sodium hydroxide solution with the mass concentration of 20 wt%, adding 25mL of the sodium hydroxide solution into the mixture, aging at 85 ℃ for 20h, filtering, washing and drying at 110 ℃. Reducing the mixture in hydrogen at 500 ℃ for 8 hours to obtain the cobalt-loaded magnesium oxide byproduct inhibitor.

Synthesis of byproduct inhibitor 2:

preparation of Ni-alumina byproduct inhibitor: 20g of nickel acetate is dissolved in 180mL of deionized water to prepare a 10 wt% nickel acetate aqueous solution. Then, 27g of silica powder was added to the above nickel acetate aqueous solution with stirring at 25 ℃ and stirred for 18 hours. Preparing an ammonia water solution with the mass concentration of 20 wt%, adding 27mL into the mixture, aging at 85 ℃ for 20h, filtering, washing and drying at 110 ℃. Reducing the mixture in hydrogen at 500 ℃ for 8h to obtain the nickel-loaded alumina byproduct inhibitor.

Synthesis of byproduct inhibitor 3:

preparation of Fe-Mn-silicon oxide byproduct inhibitor: 14.8g of ferric nitrate and 10.2g of manganese nitrate were dissolved in 225mL of deionized water to prepare a 10 wt% aqueous salt solution. Then, 27g of silica powder was added to the above aqueous solution under stirring at 25 ℃ and stirred for 18 hours. Preparing an ammonia water solution with the mass concentration of 20 wt%, adding 30mL into the mixture, aging at 85 ℃ for 20h, filtering, washing and drying at 110 ℃. Reducing the mixture in hydrogen at 500 ℃ for 8 hours to obtain the ferro-manganese composite silicon oxide byproduct inhibitor.

Comparative example 1

1kg of cumene was placed in a 2L titanium reactor equipped with a stirrer, a gas inlet at the bottom and a gas outlet at the top, which was combined with a reflux condenser, the reactor was pressurized with nitrogen to 4barg and the reaction solution was heated to 105 ℃. Once this temperature was reached, air was passed into the reactor while vigorous stirring was applied and the temperature of the liquid in the reactor was kept constant at 105 ℃. Wherein, the air is continuously fed, and the cumene is added into the reaction kettle in advance for one time.

The reflux temperature in the reflux condenser was maintained at 25 ℃ to condense the entrained organics. The air feed amount was adjusted so that the oxygen concentration measured by the oxygen concentration analyzer was maintained at 5 vol%.

Samples of the reaction mixture were taken at various time points during the reaction. The concentrations of the components in the reaction mixture (expressed as wt% based on the total reaction mixture) were measured. Where 0min represents the start of the reaction and the first sample was taken.

Comparative example 2

9g of by-product inhibitor 3 and 1kg of cumene were charged into the reaction vessel, and the other conditions were the same as in comparative example 1.

Example 1

1g of 2, 4-diphenyl-4-methyl-2-pentene, 7g of by-product inhibitor 1 and 1kg of cumene were charged into a reaction vessel, and the other conditions were the same as in comparative example 1.

Example 2

5g of 1,1, 2-trimethyl-3-phenylindane, 8g of by-product inhibitor 2 and 1kg of cumene were charged in a reaction vessel, and the other conditions were the same as in comparative example 1.

Example 3

0.02g of cis-1, 3-dimethyl-1, 3-diphenylcyclobutane, 9g of by-product inhibitor 3 and 1kg of cumene were charged into the reaction vessel, and the other conditions were the same as in comparative example 1.

Example 4

0.2g of 2, 4-diphenyl-4-methyl-1-pentene and 1kg of cumene were charged into a reaction vessel, and the other conditions were the same as in comparative example 1.

Results of the experiment

The results of the experimental sampling analysis and the results of the selectivity calculation for each component of the above comparative examples and examples are summarized in table 1.

In comparative example 2, the reaction results when only the byproduct inhibitor was added without adding α -methylstyrene dimer did not significantly change from those of comparative example 1, indicating that the addition of only the byproduct inhibitor had substantially no effect on the oxidation reaction.

In examples 1 to 3, when a small amount of α -methylstyrene dimer and byproduct inhibitor were added together, a significantly higher CHP yield in an equivalent time could be caused while the PMK production amount was effectively suppressed.

In example 4, addition of only a small amount of alpha-methylstyrene dimer, without inhibitor, resulted in significantly higher CHP production in an equivalent time, as well as an increase in PMK production.

The above experiments show that by feeding only a relatively small amount of alpha-methylstyrene dimer, the time to reach a particular CHP concentration is shortened, which is a very advantageous shortening of the reaction time (i.e. higher reaction rate) as this will advantageously result in a higher yield of CHP relative to the amount of cumene fed over a certain period of time.

In addition, the experimental results show that by feeding α -methylstyrene dimer and byproduct inhibitor simultaneously, the amount of PMK produced increases little with a significant increase in the amount of CHP produced, and at the same time, DMBA can be advantageously converted into cumene, which can be effectively recycled. Such a production scheme may occur in a process for producing propylene oxide, such as CHP/PO.

TABLE 1 comparative example and example reaction results

Claims

1. A method for preparing cumene hydroperoxide by cumene oxidation comprises the following steps: cumene is oxidized in the presence of alpha-methyl styrene dimer to prepare cumene hydroperoxide; the alpha-methyl styrene dimer is selected from one or more of 2, 4-diphenyl-4-methyl-1-pentene, 2, 4-diphenyl-4-methyl-2-pentene, 1, 2-trimethyl-3-phenylindane, cis-1, 3-dimethyl-1, 3-diphenyl cyclobutane or trans-1, 3-dimethyl-1, 3-diphenyl cyclobutane.

2. The process of claim 1, wherein the concentration of the alpha-methylstyrene dimer is from 0.001 to 1.0 wt.%, based on the total weight of the reaction liquid mixture.

3. The process of claim 2, wherein the concentration of the α -methylstyrene dimer is from 0.002 to 0.5 wt.%, based on the total weight of the reaction liquid mixture.

4. The process of claim 3, wherein the concentration of the α -methylstyrene dimer is from 0.003 to 0.3 wt.%, based on the total weight of the reaction liquid mixture.

5. The method of claim 1, wherein the method is carried out in the presence of a byproduct inhibitor; the byproduct inhibitor comprises an active component and a carrier, wherein the active component is a VIIB or VIII group element; the carrier is selected from one or more of oxides or carbonates of elements in IIA, IIIA and IVA groups of the periodic table.

6. The method of claim 5, wherein the active component is one or more of cobalt, manganese, iron; the carrier is selected from one or more of alumina, silica and magnesia.

7. The method as claimed in claim 5, wherein the content of the active component metal element in the byproduct inhibitor is 0.01-50% of the total weight of the byproduct inhibitor, and the content of the carrier is 50-99.99%.

8. The method of claim 5, wherein the byproduct inhibitor is prepared by a method comprising the steps of: (1) adding the carrier into a metal salt aqueous solution with the concentration of the active component metal element of 1-40 wt%, and stirring for 0.5-24h at 25-100 ℃; (2) adding a precipitant solution with the concentration of 1-40 wt% into the mixture obtained in the step (1), and stirring for 0.5-50h at the temperature of 25-100 ℃; (3) filtering the mixture obtained in the step (2), drying the filter cake at 25-180 ℃, and then reducing for 1-20h under the hydrogen atmosphere at 300-700 ℃ to obtain the byproduct inhibitor.

9. The method of claim 5, wherein the weight ratio of the byproduct inhibitor to the reaction liquid phase mixture is 0.0001-0.05: 1.

10. The method according to claim 5, wherein the weight ratio of the byproduct inhibitor to the reaction liquid mixture is 0.006-0.012: 1.