阅读说明：本技术 醛的脱除方法 (Method for removing aldehyde ) 是由 胡松 杨卫胜 于 2020-05-12 设计创作，主要内容包括：本发明涉及一种醛的脱除方法,将粗环氧丙烷物料送入装填有酸性、碱性或酸-碱性催化剂的反应器,在压力0～1.0MPaG,温度30～80℃,体积空速1～20h～(-1)条件下,醛和醇和/或含羟基的醇醚发生羟醛缩合反应生成重组分缩醛；控制脱轻塔塔顶操作温度在40～60℃,脱重塔塔顶操作温度在40～60℃,在脱重塔脱除重组分缩醛。所述系统、方法、和设备可产生比现有技术含有更低浓度的醛(甲醛+乙醛+丙醛)的环氧丙烷物流,可用于环氧丙烷工业生产和环氧丙烷废料回收。(The invention relates to a method for removing aldehyde, which comprises the steps of feeding a crude epoxy propane material into a reactor filled with an acidic, basic or acid-basic catalyst, and carrying out reaction at a pressure of 0-1.0 MPaG, a temperature of 30-80 ℃ and a volume space velocity of 1-20 h ‑1 Under the condition, aldehyde and alcohol and/or alcohol ether containing hydroxyl are subjected to aldol condensation reaction to generate heavy component acetal; and controlling the operation temperature of the top of the light component removal tower to be 40-60 ℃, controlling the operation temperature of the top of the heavy component removal tower to be 40-60 ℃, and removing heavy component acetal in the heavy component removal tower. The systems, methods, and apparatuses can produce propylene oxide streams containing lower concentrations of aldehydes (formaldehyde + acetaldehyde + propionaldehyde) than prior art, which can be used for propylene oxide industrial production and propylene oxide waste recovery.)

1. A process for removing aldehyde includes such steps as feeding the raw epoxy propane material to a reactor filled with catalyst, aldolizing reaction between aldehyde and hydroxy-contained component (preferably alcohol and/or hydroxy-contained alcohol ether) to obtain heavy acetal, sequentially removing light component and heavy component, and removing heavy acetal.

2. The method for removing aldehydes according to claim 1, wherein the catalyst is an acidic, basic or acid-basic catalyst.

3. The method for removing aldehydes as claimed in claim 1, wherein the reaction product is further subjected to a rectification step after the de-heavy step; preferably an extractive distillation step.

4. The method according to claim 1, wherein the aldehyde content is 0.001 to 3% and/or the hydroxyl group-containing component content is 0.001 to 8% based on the total weight of the crude propylene oxide material.

5. The method for removing aldehydes according to claim 1, wherein the reaction temperature of the reactor is 30 to 80 ℃, preferably 40 to 60 ℃.

6. The method for removing aldehydes according to claim 1, wherein the reaction pressure in the reactor is 0 to 1.0MPaG, preferably 0.10 to 0.80 MPaG.

7. The method for removing aldehyde according to claim 1, wherein the volume space velocity of the reactor is 1 to 20 hours^-1Preferably 3 to 16 hours^-1。

8. The method for removing aldehydes as claimed in claim 1, wherein the operation temperature of the top of the light component removal column is controlled to 40 to 60 ℃.

9. The method for removing aldehydes as claimed in claim 1, wherein the operation temperature of the top of the de-heavy column is 40 to 60 ℃.

10. The method for removing aldehydes according to claim 1 or 3, wherein the operation temperature of the top of the extractive distillation column is 70 to 90 ℃.

11. The method of claim 1, wherein the ketone in the crude propylene oxide feed is also reacted with an alcohol and/or a hydroxyl-containing alcohol ether to form a heavy ketal.

12. The process for removing aldehydes according to claim 1, wherein the molar ratio of hydroxyl groups to (aldehyde + ketone) in the reactor is controlled to be greater than 2.0, preferably greater than 2.1, more preferably greater than 2.2.

Technical Field

The invention relates to a method for removing aldehyde, in particular to the field of production of propylene oxide, and specifically relates to a method for removing aldehyde and ketone in the purification/refining process of propylene oxide in the processes of producing propylene oxide by using propylene and Cumene Hydroperoxide (CHP) or ethylbenzene hydroperoxide (EBHP) or tert-butyl hydroperoxide (TBHP).

Background

Propylene Oxide (PO) is an essential building block for a variety of chemicals and products, with global yields of over 700 million tons per year. The direct oxidation of propylene to PO with air or oxygen tends to yield low yields because of the strong oxidizing properties of air or oxygen. Therefore, PO is usually produced with the aid of chemical media such as peroxides.

One known process involves contacting an organic hydroperoxide and propylene with a heterogeneous epoxidation catalyst and recovering a product stream comprising PO and an alcohol. The PO/SM process is characterized in that ethylbenzene hydroperoxide (EBHP) and propylene are subjected to epoxidation reaction to generate propylene oxide, meanwhile, 1-phenylethanol is a byproduct, the 1-phenylethanol can be converted into styrene through dehydration, the styrene is used as the byproduct, and 2-3 tons of styrene are generated while 1 ton of propylene oxide is generally produced.

Another known method for producing PO is the co-production of PO and methyl tert-butyl ether (MTBE), abbreviated PO/MTBE. The process includes similar reaction steps as the styrene/PO production process described above. In the epoxidation step tert-butyl hydroperoxide is reacted with propene to form PO and tert-butanol which is subsequently etherified to MTBE, but this route is difficult to solve since MTBE has been banned in some countries and regions.

Yet another known process involves the production of PO in the presence of cumene. In this process, cumene is reacted with oxygen or air to form Cumene Hydroperoxide (CHP). Cumene hydroperoxide thus obtained is reacted with propene in the presence of an epoxidation catalyst to yield PO and α, α -dimethylbenzyl alcohol (DMBA). The latter can be converted into isopropyl benzene by means of heterogeneous catalyst and hydrogen, and the isopropyl benzene can be recycled.

Following recent developments, it is also known to produce PO from propylene in the presence of hydrogen peroxide as a medium, known as the HPPO process.

Regardless of the particular epoxidation process used, the PO product typically requires purification to remove by-products and impurities. Indeed, for most applications, it is important to reduce the impurities in PO to very low levels.

Some of the by-products of the epoxidation process can be easily separated by distillation. However, epoxidation processes also tend to form by-products and impurities that are more difficult to separate. Epoxidation using an organic hydroperoxide will be used as an example, the organic hydroperoxide is mainly reduced to the corresponding alcohol, which tends to separate easily. However, small amounts of other oxygenates such as methanol, acetone, acetaldehyde, propionaldehyde, and the like, as well as hydrocarbons, are also produced, which are difficult to separate and typically remain as impurities in the PO product (even after conventional distillation). The hydrocarbon impurities associated with PO are believed to be derivatives of propylene having 4 to 7 carbon atoms per molecule, especially derivatives having 6 carbon atoms per molecule. The C is₆The compounds mainly comprise methyl pentenes and methyl pentanes. Other epoxidation processes also result in the formation of impurities having the same or similar structure that are similarly difficult to separate.

The separation of typical impurities in PO often requires multiple distillation steps. Moreover, final purification (or refining) to high purity levels by distillation typically requires very large size columns, especially where the relative volatility of the impurities is low compared to PO.

It is known to use extractive distillation techniques to assist in the separation of impurities having low relative volatility. For example, USA3909366 describes the purification of propylene oxide by extractive distillation in the presence of aromatic hydrocarbons having from 6 to 12 carbon atoms, such as ethylbenzene. Various other extractive distillation solvents have also been suggested, including, for example, cyclic paraffins (see USA3464897), lower glycols (see USA3578568), water (see USA4140588), t-butanol (see USA5006206) and heptane. However, in this method, the column diameter of the separation column is still large.

USA5772854 relates to the use of so-called "acid pair" reboilers, i.e. reboilers connected in series, in the purification of propylene oxide. In particular, USA5772854 provides a process for purifying a propylene oxide feedstock contaminated with water, methanol and acetone in an extractive distillation column in the presence of an oxyalkylene glycol extractive distillation agent under distillation conditions selected to promote the formation and maintenance of an acetone buffer in the distillation column, wherein a higher boiling (heavy) fraction containing substantially all of the oxyalkylene glycol, water and acetone is continuously withdrawn from the distillation column and said higher boiling (heavy) fraction is partially evaporated in a first reboiler; the remaining liquid is partially vaporized in the second reboiler and the vapor is recycled to the extractive distillation column. GBA1549743 relates to a method for controlling the heat input into the reboiler section of a distillation column to increase the separation efficiency to obtain the desired end product. In GBA1549743 the "reboiler section" is defined at page 1, lines 62-64 as the part of the column below the lowest tray. Thus, it will be understood that the so-called "reboiler section" described in GBA1549743 is the bottom compartment of the distillation column. The process of GBA1549743 comprises withdrawing a liquid bottoms stream from a partially divided reboiler section of a distillation column, introducing a first portion of the liquid bottoms stream material to a first reboiler, introducing a mixed phase bottoms stream material produced in the first reboiler to a substantially liquid free region of the reboiler section, introducing a second portion of the liquid bottoms stream material to a second reboiler, and introducing the mixed phase bottoms stream material produced in the second reboiler to the same substantially liquid free region of the reboiler section as the mixed phase bottoms stream material produced in the first reboiler. Thus, in the process of GBA1549743, it will be understood that liquid bottoms material is withdrawn from the section below the lowest tray in the distillation column and that the mixed phase bottoms from the first and second reboilers are also returned to the same location in the distillation column, i.e. below the lowest tray in the distillation column. This is clearly shown in the figure in GBA1549743, where a liquid bottoms stream material is withdrawn from the so-called reboiler section through outlet 25 and the mixed phase bottoms stream from the first and second reboilers is returned through inlets 30 and 34 also in the reboiler section. The lowest tray in the figure is 11. PO purification by distillation and overall PO production is very energy intensive, especially considering the need for large size columns. It is an object of the invention to provide a method and a system for separating impurities from PO which also allows energy saving.

The propylene oxide product has strict requirements on water, aldehyde and isomers, the water can influence the hydroxyl value and the foaming performance of a polymer, the aldehyde can cause the product to emit peculiar smell and influence the health of people, and the isomers are end capping agents of long polymer chains, so that the product purity is strictly required in national standards and enterprise standards.

The quality and purity requirements of the high-class products of the propylene oxide in the national standard are as follows: more than or equal to 99.95 percent of propylene oxide, less than or equal to 0.02 percent of water, less than or equal to 0.005 percent of acetaldehyde and propionaldehyde, and less than or equal to 0.003 percent of acid.

The quality and purity requirements of the propylene oxide superior products in the enterprise standards are as follows: more than or equal to 99.99 percent of propylene oxide, less than or equal to 0.003 percent of water, less than or equal to 0.001 percent of acetaldehyde and propionaldehyde, and less than or equal to 0.001 percent of acid.

The crude propylene oxide produced by the reaction usually contains impurities such as water, formaldehyde, acetaldehyde, propionaldehyde, methanol, acetone, methyl formate and the like, and because the impurities and propylene oxide form an azeotrope or the relative volatility is close to 1, the common rectification can not reach the standards of the propylene oxide products. In order to obtain propylene oxide of high purity which meets the polymerization requirements, it is necessary to separate and remove impurities contained in the propylene oxide. Most of the existing industrial devices adopt a method of firstly adopting common rectification to remove C₃～C₄Light components such as hydrocarbons, formaldehyde, acetaldehyde, methyl formate and the like, heavy components such as water, propionaldehyde, methanol, acetone, propylene glycol and the like are removed by adopting common rectification, residual oxygen-containing compound impurities such as aldehydes, water, methyl formate and the like are extracted by adopting an extractive rectification method, the residual oxygen-containing compound impurities are removed by using a water washing method, and C is generally adopted for extractive rectification₇～C₂₀Straight-chain and branched-chain hydrocarbons and/or glycols are used as extractants. For economic reasons, the purification of propylene oxide uses C₈The mixture of the straight chain alkane and the branched chain alkane is used as an extracting agent, the adding of the extracting agent increases the relative volatility of acetaldehyde, water, methanol and methyl formate to the propylene oxide, the acetaldehyde, the water, the methanol and the methyl formate are removed from the top of the tower, and the extracting agent is recycled.

In the separation process, chemical reaction is inevitable, the most common epoxypropane hydrolysis reaction generates 1, 2-propylene glycol, epoxypropane and methanol react to generate propylene glycol monomethyl ether, the newly generated impurities have stable properties and are heavy components, and can be removed in the process of de-heavy separation or extraction rectification, and the quality of the epoxypropane product can be ensured by control; CN103562192B reports that the above method has the technical risk that formaldehyde, acetaldehyde and propionaldehyde can undergo aldol condensation reaction with methanol (the carbonyl group of aldehyde is added by the hydroxyl group of alcohol, and the original carbonyl carbon is connected with an alcoholic hydroxyl group and an ether bond) to generate hemiacetal and/or acetal, the reaction product is heavier than the reactant, and the separation difficulty is reduced; however, hemiacetals are unstable and either continue to form acetals or decompose back to aldehydes and alcohols. That is, in the light component removal step, without chemical reaction, most of formaldehyde and acetaldehyde can be theoretically removed as light components, but part of formaldehyde and acetaldehyde reacts with alcohols such as methanol to generate hemiacetal and acetal, and the hemiacetal and the heavy components enter the heavy component removal step.

USA3350417A, for a process for producing propylene oxide by the chlorohydrin process, the bottoms from column 28 comprising propylene oxide, acetaldehyde and methyl formate are fed via line 31 to aldol condensation-saponification vessel 36. A500 ml stirred tank reactor was charged with 3N aqueous sodium hydroxide solution in which acetaldehyde was hydroformylated and methyl formate was saponified at the same time. The reactor was operated at about 50 c and 5 atmospheres with a reactor residence time of about 25 minutes. Generally, reactor 36 can be operated at a temperature of 0 to 200 deg.C, preferably 25 to 75 deg.C, and a pressure sufficient to maintain a liquid phase, preferably 1 to 10 atmospheres. Two or more aldol condensation saponifying agents are used to simultaneously perform aldol condensation of acetaldehyde and saponification of methyl formate. The methyl formate and sodium hydroxide solution are saponified to produce sodium formate and methanol, and the methanol and acetaldehyde are condensated with aldol. USA3350417A suffers as follows: the method has the advantages that the epoxypropane is easy to hydrolyze, and particularly, under the conditions of existence of alkali liquor and stirring, the epoxypropane is hydrolyzed to generate propylene glycol, so that the epoxypropane yield is reduced; and the treatment of the salt-containing wastewater such as sodium formate is difficult.

CN110003136A discloses a method for removing impurities from propylene oxide, which comprises the step of converting aldehyde ketone impurities into corresponding acetals and ketals through a crude separation tower and a reactor filled with a catalyst. The reaction temperature of the reactor is 20-60 ℃, the reaction pressure is 0.2-2.0 Mpa, and the volume space velocity of the reactor passing through the fixed bed is 0.1-10h^-1The reaction comprises adding an alcohol auxiliary agent, wherein the weight ratio of the alcohol auxiliary agent to the aldehyde ketone impurities is (3-20): 1. then the material enters a PO rectifying tower for refining, a PO product is obtained at the tower top, and a mixed solution containing ketal and acetal is obtained at the tower bottom. In addition, this patent document further describes that the total content of the feed aldehyde ketone impurities from the PO crude separation column is 110ppm, and the content of the discharged aldehyde ketone impurities obtained by this method is 5ppm or less. However, the invention relates to a complex and highly efficient recovery and condensation of the auxiliary agentAldehyde ketal treatment procedure, as follows: obtaining mixed liquid containing ketal and acetal at the bottom of the tower; and (2) adding an acid solution into the mixed solution discharged from the bottom of the tower to adjust the pH value, carrying out hydrolysis reaction for a period of time at a certain temperature, entering an auxiliary agent extraction tower, recovering the high-efficiency auxiliary agent by using an extracting agent, distilling and extracting an oil layer, separating to obtain the high-efficiency auxiliary agent, returning the high-efficiency auxiliary agent to the step (1) for recycling, and returning the recovered extracting agent to the auxiliary agent extraction tower, so that the economy is poor.

Therefore, the addition of a large amount of hydroxyl group-containing substances requires recovery of the unreacted hydroxyl group-containing substances, which leads to a significant increase in the operating costs and the equipment investment.

Therefore, the above method has difficulty in removing aldehydes due to inevitable chemical reactions during the separation process.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a method for removing aldehyde, which comprises the steps of feeding a crude epoxy propane material into a reactor filled with a catalyst, carrying out aldol condensation reaction on aldehyde and a component containing hydroxyl (preferably alcohol and/or alcohol ether containing hydroxyl) to generate heavy component acetal, sequentially carrying out light component removal and heavy component removal on reaction products, and removing the heavy component acetal in the heavy component removal step.

The aldol condensation reaction catalyst is an acidic, basic or acid-basic catalyst.

The commonly used acidic catalyst is (VO)₂P₂O₇、α-VOHPO₄Niobic acid and MFI zeolite, and the like. In the cationic active center of the acidic catalyst, the aldehyde carbonyl group is activated to form an enol carbonium ion so that condensation reaction occurs.

The basic catalysts commonly used include basic compounds (oxides, hydroxides, bicarbonates, carbonates and carboxylates of alkali metals or alkaline earth metals), organic amine compounds, anion exchange resins and the like. Since propylene oxide is hydrolyzed in the presence of water and a strong base, a weakly basic catalyst and an anion exchange resin catalyst are preferred.

The acid-base catalyst has both acid-base active centers, such as some binary oxides (Ni-P, Mn-P, Fe-P and V-P) or hydrotalcite, etc.

Rectifying the aldol condensation reaction product after the step of removing the heavy component; preferably an extractive distillation step.

The invention utilizes the catalytic reaction of the aldol condensation reaction catalyst to convert aldehyde (ketone) and alcohol into heavy component acetal (ketal) instead of staying in unstable hemiacetal, and the stable heavy component acetal (ketal) is beneficial to separation and purification of propylene oxide.

The reaction of aldehydes (ketones) and alcohols to give hemiacetals (hemiketals) and acetals (ketals) is of the general formula:

in propylene oxide systems, acetone and methanol may also react to form acetonitrilic alcohol.

Three examples are described below in which formaldehyde, acetaldehyde, propionaldehyde and hydroxyl group-containing substances such as methanol, propylene glycol, ethylene glycol monomethyl ether are subjected to aldol condensation reaction.

The reaction of formaldehyde and methanol to form hemiacetals and acetals is as follows:

the reaction of acetone and methanol to form hemiketal and ketal is as follows:

the reaction of acetaldehyde with propylene glycol to form hemiacetal and acetal has the following formula:

the reaction of propionaldehyde and propylene glycol monomethyl ether to form hemiacetal and acetal has the following formula:

the reaction formula of propionaldehyde and ethylene glycol monomethyl ether to generate hemiacetal and acetal is as follows:

the alcohol and/or the alcohol ether containing hydroxyl can be alcohols such as methanol and propylene glycol contained in the crude epoxy propane material, ethylene glycol monomethyl ether, propylene glycol monomethyl ether and other impurities, and can also be added later; methanol is mainly from propylene epoxidation byproducts; propylene glycol is derived from propylene oxide hydrolysate, is produced during epoxidation reaction, and is produced during separation, and in addition, patents and documents report that propylene glycol is adopted as an extracting agent, and a certain amount of propylene glycol is contained in discharged waste containing propylene oxide; propylene glycol monomethyl ether is generated in the epoxidation reaction and the separation process, and the amount is small; in the separation and purification process of the propylene oxide, ethylene glycol monomethyl ether is used as an extracting agent in part of process routes, and a certain amount of ethylene glycol monomethyl ether is contained in the discharged waste containing the propylene oxide. Wherein, alcohols such as methanol and propylene glycol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether and other hydroxyl-containing impurities can be used as raw materials for reacting with aldehyde to generate heavy components such as hemiacetal and acetal; the discharged waste containing the propylene oxide can be recycled, and the propylene glycol and the ethylene glycol monomethyl ether contained in the waste can be used as raw materials for reacting with aldehyde, so that the waste is recycled, and the discharge of three wastes is reduced.

Because the temperature is increased, the reverse reaction of hemiacetal and acetal is favorable for generating aldehyde and alcohol again, and in the reactor, the reverse reaction is not expected to occur in a light component removing tower and a heavy component removing tower, so the reaction temperature of the reactor is set to be 30-80 ℃.

Based on the total weight of the crude propylene oxide material, the content of aldehyde is 0.001-3 percent, and/or the content of the component containing hydroxyl is 0.001-8 percent.

The reaction temperature of the aldol condensation reactor is 30-80 ℃, and preferably 40-60 ℃.

The reaction pressure of the reactor is 0-1.0 MPaG, preferably 0.10-0.80 MPaG, and the reaction is ensured to be carried out under the condition of full liquid phase.

The volume airspeed of the reactor is 1-20 h^-1Preferably 3 to 16 hours^-1。

The molar ratio of hydroxyl groups to (aldehyde + ketone) in the reactor is controlled to be greater than 2.0, preferably greater than 2.1, more preferably greater than 2.2.

And controlling the operation temperature of the top of the lightness-removing tower to be 40-60 ℃.

The operation temperature of the top of the de-heavy tower is 40-60 ℃.

The process, after de-weighting, produces a propylene oxide stream containing less than 1ppm formaldehyde.

The process, after de-weighting, produces a propylene oxide stream comprising less than 20ppm acetaldehyde + propionaldehyde.

If the performance of the catalyst is reduced or the separation operation such as rectification and the like has problems, a small amount of hemiacetal and acetal can enter the extraction and rectification tower, or aldehyde and/or methanol have residues, and aldol condensation reaction can still occur in the process of removing aldehyde and alcohol by the extraction and rectification tower in the extraction and rectification tower, so the invention avoids the generation of the hemiacetal and the hemiacetal by the method of increasing the operation temperature of the extraction and rectification tower. Therefore, the operation temperature of the top of the extraction and rectification tower is 70-90 ℃.

The process produces a propylene oxide stream containing less than 0.1ppm formaldehyde after extractive distillation, wherein the propylene oxide stream is depleted of extractant.

The process produces a propylene oxide stream after extractive distillation containing less than 10ppm acetaldehyde + propionaldehyde, wherein the propylene oxide stream is depleted of extractant.

In the method, the ketone can also react with alcohol and/or alcohol ether containing hydroxyl to generate heavy ketal. However, in the propylene oxide system, from laboratory experiments and literature reports, the ketone is mainly acetone, and acetone and propylene oxide are relatively easy to separate, so that the aldol condensation reaction of the ketone is not the key point of the invention, the invention focuses on formaldehyde, acetaldehyde and propionaldehyde which are difficult to separate, and high-concentration aldehyde is easy to polymerize and block equipment and pipelines. The invention can remove residual aldehyde, water, methyl formate and other oxygen-containing compounds by extracting and rectifying after removing the heavy components.

If the boiling points of acetone and butylene oxide are close in a1, 2-butylene oxide system and the separation is difficult, the aldol condensation reaction of ketone is adopted, and the heavy component removal by a heavy component removal tower is obviously beneficial.

Drawings

FIGS. 1 and 2 are process flow diagrams of the present invention.

In FIG. 1, the reactor A, the light component removal tower B and the heavy component removal tower C are shown. 1-crude propylene oxide material flow, 2-reaction product, 3-nitrogen, 4-light component removal tower top extraction, 5-light component removal tower bottom liquid, 6-heavy component removal tower top extraction and 7-heavy component removal tower bottom liquid.

In FIG. 2, the reactor A, the light component removal tower B, the heavy component removal tower C and the extraction tower D. 1-crude propylene oxide material flow, 2-reaction product, 3-nitrogen, 4-light component removal tower top extraction, 5-light component removal tower bottom liquid, 6-heavy component removal tower top extraction, 7-heavy component removal tower bottom liquid, 8-extractant feeding, 9-extraction tower top extraction and 10-extraction tower bottom liquid.

The method comprises the following steps of enabling a crude propylene oxide material flow 1 to enter a reactor A, enabling an aldehyde (ketone) and an alcohol or an alcohol ether containing hydroxyl to carry out an aldol condensation reaction in the reactor to generate an acetal and a ketal, enabling a reaction product to enter a light component removal tower B, introducing a nitrogen material flow into the tower top, extracting a material flow 4 containing light hydrocarbons such as C3-C5, formaldehyde and acetaldehyde from the tower top, extracting a material flow 5 from a tower bottom to enter a heavy component removal tower, enabling the tower top to be a heavy component removal tower, enabling the tower bottom to be water, methanol, acetone, propionaldehyde, acetal, ketal, cumene, ethylbenzene and other hydrocarbons, enabling heavy component material flows 7 and 8 to be extracting agent feeding materials, generally C7 and above hydrocarbons, enabling 9 to be extracted from the tower top of an extraction tower and mainly contain residual aldehydes, oxygen-containing compounds such as methanol, water and methyl formate, enabling 10 to be a mixed liquid of propylene oxide and an extracting agent, and generally containing trace C5-C6 hydrocarbons.

Detailed Description

[ example 1 ]

As shown in fig. 2, a crude propylene oxide material flow 1 enters a reactor a, an aldehyde (ketone) and an alcohol and/or an alcohol ether containing a hydroxyl group undergo an aldol condensation reaction in the reactor to generate an acetal and a ketal, a reaction product enters a lightness-removing tower B, a nitrogen material flow is introduced into the tower top, a material flow 4 containing light hydrocarbons such as C3-C5, formaldehyde and acetaldehyde is extracted from the tower top, a material flow 5 extracted from the tower bottom enters a de-weighting tower, the tower top is a de-weighted crude propylene oxide 6, and the tower bottom is a heavy component material flow 7 such as water, methanol, acetone, propionaldehyde, acetal, ketal, cumene, ethylbenzene and the like, and propylene glycol.

The aldol condensation reaction catalyst is (VO)₂P₂O₇。

The crude propylene oxide stream 1 had a feed mass composition of propylene oxide 98.6000%, C₃0.1720% of hydrocarbon, 0.1500% of formaldehyde, 0.2580% of acetaldehyde, 0.1500% of propionaldehyde, 0.1500% of acetone, 0.1500% of methyl formate, 0.1500% of methanol, 0.1500% of water, 0.0500% of propylene glycol and 0.0200% of isopropylbenzene.

The mass flow of propylene glycol added per crude propylene oxide stream 1 was 1.052%, or the mass flow of ethylene glycol monomethyl ether added per crude propylene oxide stream 1 was 2.104%. The molar ratio of hydroxyl group to aldehyde + ketone was controlled to 2.10.

The reaction temperature of the reactor A is 30 ℃, the reaction pressure is 0.10MPaG, and the volume space velocity of the reactor is 2h^-1And the reaction is ensured to be carried out under the condition of full liquid phase.

The operation temperature of the top of the light component removal tower is controlled to be 40 ℃, and the operation temperature of the top of the heavy component removal tower is controlled to be 42 ℃.

The content of formaldehyde in the propylene oxide material flow after the weight removal is 0, the content of aldehyde (formaldehyde + acetaldehyde + propionaldehyde) in the propylene oxide material flow after the extraction and rectification is less than or equal to 6ppm, wherein the extractant is deducted from the propylene oxide material flow.

[ example 2 ]

The same as in example 1, except that the crude propylene oxide stream 1 had a feed mass composition of 98.3200% propylene oxide, C₃0.1020% of hydrocarbons, 0.1200% of formaldehyde, 0.2735% of acetaldehyde, 0.2530% of propionaldehyde, 0.2030% of acetone, 0.1505% of methyl formate, 0.1525% of methanol, 0.2505% of water, 0.1500% of propylene glycol and 0.0250% of isopropyl benzene.

AldolsThe condensation reaction catalyst is alpha-VOHPO₄。

The mass flow of propylene glycol added per crude propylene oxide stream 1 was 1.156%, or the mass flow of ethylene glycol monomethyl ether added per crude propylene oxide stream 1 was 2.312%. The molar ratio of hydroxyl group to aldehyde + ketone was controlled to 2.16.

The reaction temperature of the reactor A is 35 ℃, the reaction pressure is 0.25MPaG, and the volume space velocity of the reactor is 6h^-1And the reaction is ensured to be carried out under the condition of full liquid phase.

The operation temperature of the top of the lightness-removing column is controlled at 43 ℃. The operation temperature of the top of the de-heavy tower is 45 ℃.

The content of formaldehyde in the propylene oxide material flow after the weight removal is 0, the content of aldehyde (formaldehyde + acetaldehyde + propionaldehyde) in the propylene oxide material flow after the extraction and rectification is less than or equal to 7ppm, wherein the extractant is deducted from the propylene oxide material flow.

[ example 3 ]

The same as in example 1, except that the crude propylene oxide stream 1 had a feed mass composition of 96.8780% propylene oxide, C₃0.0020 percent of hydrocarbon, 0.3000 percent of formaldehyde, 0.5000 percent of acetaldehyde, 0.4500 percent of propionaldehyde, 0.4500 percent of acetone, 0.2500 percent of methyl formate, 0.1500 percent of methanol, 0.5500 percent of water, 0.3500 percent of propylene glycol and 0.1200 percent of isopropyl benzene.

The catalyst for aldol condensation reaction is MFI zeolite.

The mass flow of propylene glycol added per crude propylene oxide stream 1 was 2.612% and the hydroxyl and aldehyde + ketone molar ratio was controlled to 2.24.

The reaction temperature of the reactor A is 42 ℃, the reaction pressure is 0.35MPaG, and the volume space velocity of the reactor is 9h^-1And the reaction is ensured to be carried out under the condition of full liquid phase.

The operation temperature of the top of the light component removal tower is controlled to be 45 ℃, and the operation temperature of the top of the heavy component removal tower is controlled to be 48 ℃.

The content of formaldehyde in the propylene oxide material flow after the weight removal is 0, the content of aldehyde (formaldehyde + acetaldehyde + propionaldehyde) in the propylene oxide material flow after the extraction and rectification is less than or equal to 8ppm, wherein the extractant is deducted from the propylene oxide material flow.

[ example 4 ]

The same as in example 1, except that the crude propylene oxide stream 1 had a feed mass composition of 95.8040% propylene oxide, C₃0.0020 percent of hydrocarbons, 0.3500 percent of formaldehyde, 0.5500 percent of acetaldehyde, 0.3500 percent of propionaldehyde, 0.4500 percent of acetone, 0.2500 percent of methyl formate, 0.1500 percent of methanol, 0.5240 percent of water, 0.3500 percent of propylene glycol, 0.1200 percent of isopropyl benzene, 0.1000 percent of ethylbenzene and 1.0000 percent of ethylene glycol monomethyl ether.

The aldol condensation reaction catalyst is a weakly basic catalyst.

The mass flow of propylene glycol added per crude propylene oxide stream 1 was 2.319%, and the hydroxyl and aldehyde + ketone molar ratio was controlled to 2.32.

The reaction temperature of the reactor A is 49 ℃, the reaction pressure is 0.56MPaG, and the volume space velocity of the reactor is 12h^-1And the reaction is ensured to be carried out under the condition of full liquid phase.

The operation temperature of the top of the light component removal tower is controlled at 48 ℃, and the operation temperature of the top of the heavy component removal tower is controlled at 50 ℃.

The content of formaldehyde in the propylene oxide material flow after the weight removal is 0, the content of aldehyde (formaldehyde + acetaldehyde + propionaldehyde) in the propylene oxide material flow after the extraction and rectification is less than or equal to 8ppm, wherein the extractant is deducted from the propylene oxide material flow.

[ example 5 ]

The same as in example 1, except that the crude propylene oxide stream 1 had a feed mass composition of 95.2280% propylene oxide, C₃0.0020 percent of hydrocarbon, 0.3500 percent of formaldehyde, 0.5500 percent of acetaldehyde, 0.4000 percent of propionaldehyde, 0.4500 percent of acetone, 0.2500 percent of methyl formate, 0.1500 percent of methanol, 0.5500 percent of water, 0.3500 percent of propylene glycol, 0.1200 percent of isopropyl benzene, 0.1000 percent of ethylbenzene and 1.5000 percent of ethylene glycol monomethyl ether.

The aldol condensation reaction catalyst is an anion exchange resin catalyst.

The mass flow of propylene glycol added per crude propylene oxide stream 1 was 2.264%, and the hydroxyl and aldehyde + ketone molar ratio was controlled to 2.40.

The reaction temperature of the reactor A is 55 ℃, the reaction pressure is 0.75MPaG, and the volume space velocity of the reactor is 16h^-1And the reaction is ensured to be carried out under the condition of full liquid phase.

The operation temperature of the top of the light component removal tower is controlled to be 51 ℃, and the operation temperature of the top of the heavy component removal tower is controlled to be 53 ℃.

The content of formaldehyde in the propylene oxide material flow after the weight removal is 0, the content of aldehyde (formaldehyde + acetaldehyde + propionaldehyde) in the propylene oxide material flow after the extraction and rectification is less than or equal to 7ppm, wherein the extractant is deducted from the propylene oxide material flow.

[ example 6 ]

The same as in example 1, except that the crude propylene oxide stream 1 had a feed mass composition of 93.7780% propylene oxide, C₃0.0020 percent of hydrocarbon, 0.3500 percent of formaldehyde, 0.5500 percent of acetaldehyde, 0.5500 percent of propionaldehyde, 0.4500 percent of acetone, 0.2500 percent of methyl formate, 0.1500 percent of methanol, 0.5500 percent of water, 0.1500 percent of propylene glycol, 0.1200 percent of isopropyl benzene, 0.1000 percent of ethylbenzene and 3.0000 percent of ethylene glycol monomethyl ether.

The catalyst for aldol condensation reaction is Fe-P binary oxide.

The molar ratio of hydroxyl to aldehyde + ketone in the feed is 2.32, and no hydroxyl-containing component such as propylene glycol is required to be added.

The reaction temperature of the reactor A is 60 ℃, the reaction pressure is 0.96MPaG, and the volume space velocity of the reactor is 19h^-1And the reaction is ensured to be carried out under the condition of full liquid phase.

The operation temperature of the top of the light component removal tower is controlled at 58 ℃, and the operation temperature of the top of the heavy component removal tower is controlled at 56 ℃.

The content of formaldehyde in the propylene oxide material flow after the weight removal is 0, the content of aldehyde (formaldehyde + acetaldehyde + propionaldehyde) in the propylene oxide material flow after the extraction and rectification is less than or equal to 8ppm, wherein the extractant is deducted from the propylene oxide material flow.

[ example 7 ]

The same as in example 1, except that the crude propylene oxide stream 1 had a feed mass composition of 98.9614% propylene oxide, C₃0.1020% of hydrocarbons, 0.0010% of formaldehyde, 0.0020% of acetaldehyde, 0.0020% of propionaldehyde, 0.2030% of acetone, 0.1505% of methyl formate, 0.1500% of methanol, 0.2530% of water, 0.1500% of propylene glycol and 0.0249% of isopropyl benzene.

The aldol condensation reaction catalyst is hydrotalcite.

The molar ratio of hydroxyl to aldehyde + ketone in the feed was 2.39, and no hydroxyl-containing component such as propylene glycol was added.

The reaction temperature of the reactor A is 60 ℃, the reaction pressure is 0.80MPaG, and the volume space velocity of the reactor is 16h^-1And the reaction is ensured to be carried out under the condition of full liquid phase.

The operation temperature of the top of the light component removal tower is controlled at 58 ℃, and the operation temperature of the top of the heavy component removal tower is controlled at 56 ℃.

The content of formaldehyde in the propylene oxide material flow after the weight removal is 0, the content of aldehyde (formaldehyde + acetaldehyde + propionaldehyde) in the propylene oxide material flow after the extraction and rectification is less than or equal to 5ppm, wherein the extractant is deducted from the propylene oxide material flow.