CN109761772B - Method and device for separating and refining polymethoxy dimethyl ether - Google Patents
Method and device for separating and refining polymethoxy dimethyl ether Download PDFInfo
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Abstract
The invention relates to a method and a device for separating and refining polymethoxy dimethyl ether, which adopts multi-stage rectification to feed methanol, formaldehyde, water, trioxymethylene and PODE2Make-up water is introduced into the rectifying tower of the mixture, and the aqueous solution of formaldehyde and trioxymethylene are extracted from the tower kettle, thereby realizing the purpose of separating formaldehyde and trioxymethylene. The formaldehyde separated by the process can not be polymerized to block condensers and pipelines, the use continuity of equipment is improved, and unreacted raw materials of formaldehyde, and reaction byproducts of methyl formate and PODE (dimethyl formiate) can be effectively recovered2And the like.
Description
Technical Field
The invention belongs to the technical field of chemical engineering, and relates to a technology for synthesizing a synthetic product mixture of polymethoxy dimethyl ether by separating methanol and a formaldehyde water solution through multi-stage rectification, in particular to a method and a device for separating and refining the polymethoxy dimethyl ether.
Background
The polymethoxy dimethyl ether is a novel diesel additive, and the chemical formula is represented as CH3O(CH2O)nCH3(wherein n is more than or equal to 1, generally less than 10), has higher oxygen content (42-51%) and cetane number (average up to 76), and the PODE (peroxidase) is3-5Is the most ideal diesel oil additive, and PODE is added into the diesel oil3-5Can effectively reduce the emission of soot and Particulate Matters (PM) of the diesel engine and improve the fuel economy. PODEn is a homologue component formed from the etherification end group-providing starting material and the methoxy group-providing starting material via polycondensation under acid catalysis. The compounds providing the terminal group include methanol, dimethyl ether, methylal, etc., and the compounds providing the methoxy group include formaldehyde, trioxane, paraformaldehyde, etc.
For many years, a large amount of researches on the synthesis and separation processes of PODEN have been carried out by domestic and foreign research teams mainly based on BASF corporation, and mainly reported are a methylal and trioxymethylene route (US 20070260094) of BASF corporation and a methylal and paraformaldehyde route (CN104974025A) of Qinghua university and Yuhuang chemical cooperation, but because the reaction raw materials are anhydrous trioxymethylene and paraformaldehyde, the reaction product composition is simple, and the separation process cannot be suitable for the separation of the synthesis product of methanol and formaldehyde aqueous solution; in addition, the reaction and separation processes of methanol and formaldehyde aqueous solution (US 2008207954, US 20080221368, US 7671240 and US 7700809) of BASF company have the disadvantages of low single-pass conversion rate, complex separation process, large energy consumption for repeated heating and separation of materials and serious equipment corrosion, and greatly limit the industrialization of the process flow.
Disclosure of Invention
The synthesis process of preparing PODEN by using methanol and formaldehyde aqueous solution as raw materials is divided into two steps, wherein the first step is a reaction stage of formaldehyde and methanol reacting to generate methylal, and the second step is a reaction stage of methylal and formaldehyde reacting to generate PODEN.
The invention aims to provide a method for preparing a catalyst in the presence of methanol, formaldehyde, water, trioxymethylene and PODE2The method and the device realize the separation and the refining of polyoxymethylene dimethyl ethers (PODON) by introducing make-up water into a rectifying tower of the mixture. Separating the synthesized product of PODEN with methanol and formaldehyde solution as material by distillation, refining to obtain PODEN suitable for diesel oil component, and recovering part of the material for the first and second stage reaction.
The raw materials of the invention are methanol, formaldehyde, water, trioxymethylene and PODE2The method and the device for realizing the separation and the refining of the polymethoxy dimethyl ether by introducing the make-up water into the rectifying tower of the mixture comprise six rectifying towers and a dehydration unit.
The technical scheme of the invention is as follows:
a process for separating and refining polymethoxy dimethyl ether includes multi-stage rectification while adding methanol, formaldehyde, water, trioxymethylene and PODE2Make-up water is introduced into the rectifying tower of the mixture, and the aqueous solution of formaldehyde and trioxymethylene are extracted from the tower kettle, thereby realizing the purpose of separating formaldehyde and trioxymethylene。
And the mass ratio of the addition amount of the make-up water to the feeding is 0.3: 1-1: 1.
Furthermore, make-up water is added from the same feed port as the feed or from two separate feed ports.
The raw materials include methanol, formaldehyde, water, trioxymethylene and PODE2Make-up water separation PODE's device is introduced to the rectifying column of mixture, including six rectifying columns and a dehydration unit, the feed inlet of pipe connection second rectifying column is passed through in the tower cauldron export of first rectifying column, the feed inlet of pipe connection fourth rectifying column is passed through in the top of the tower export of second rectifying column, the feed inlet of pipe connection third rectifying column is passed through in the tower cauldron export of second rectifying column, the feed inlet of fifth rectifying column is connected to the tower cauldron discharge gate of fourth rectifying column, the feed inlet of pipe connection dehydration unit is passed through to the top of the tower discharge gate of fifth rectifying column, the feed inlet of sixth rectifying column is connected to the discharge gate of dehydration unit, its characterized in that: and introducing make-up water into the fifth rectifying tower, wherein the make-up water is added from the feed inlet of the fifth rectifying tower or a make-up water inlet is arranged on the fifth rectifying tower.
The raw materials include methanol, formaldehyde, water, trioxymethylene and PODE2The method for separating PODE by introducing additional water into the rectifying tower of the mixture comprises the following steps: feeding PODEN raw material into a first rectifying tower, and extracting a material of methyl formate from the top of the first rectifying tower; the material at the bottom of the first rectifying tower enters a second rectifying tower, and methylal, methanol, water, formaldehyde, trioxymethylene and PODE are extracted from the top of the second rectifying tower2The mixed materials of (1); the material at the bottom of the second rectifying tower enters a third rectifying tower, and PODE is extracted from the top of the third rectifying tower3-5The material and the tower bottom are PODE6-10The material (2); feeding the material at the top of the second rectifying tower into a fourth rectifying tower, and extracting the material of methylal and methanol at the top of the fourth rectifying tower; feeding the tower bottom material of the fourth rectifying tower into a fifth rectifying tower, introducing make-up water into the fifth rectifying tower, and collecting materials of formaldehyde water solution and trioxymethylene from the tower bottom of the fifth rectifying tower; the material at the top of the fifth rectifying tower enters a dehydration unit, and the moisture is removed; the material after water removal enters a sixth rectifying tower and the top of the sixth rectifying towerThe material extracted is methanol and the PODE extracted from the tower bottom2The material of (1). The operating pressure of the first rectifying tower is 100-200KPa, the operating temperature of the tower top is 30-60 ℃, the operating pressure of the second rectifying tower is 80-120KPa, the operating temperature of the tower top is 70-100 ℃, the operating pressure of the third rectifying tower is 1-50KPa, the operating temperature of the tower top is 50-150 ℃, the operating pressure of the fourth rectifying tower is 100-200KPa, the operating temperature of the tower top is 35-70 ℃, the operating pressure of the fifth rectifying tower is 80-120KPa, the operating temperature of the tower top is 70-120 ℃, the mass ratio of the make-up water content to the materials is 0.3: 1-1: 1, the operating pressure of the sixth rectifying tower is 100-200KPa, and the operating temperature of the tower top is 60-90 ℃.
The feed materials are methanol, formaldehyde, water, trioxymethylene and PODE2The rectifying column of mixture introduces supplementary water separation PODE's device, including six rectifying columns and a dehydration unit, the top of the tower export of first rectifying column passes through the feed inlet of tube coupling third rectifying column, the tower cauldron export of first rectifying column passes through the feed inlet of tube coupling second rectifying column, the top of the tower export of third rectifying column passes through the feed inlet of tube coupling fourth rectifying column, the tower cauldron export of third rectifying column passes through the feed inlet of tube coupling fifth rectifying column, the feed inlet of dehydration unit is connected to the top of the tower discharge gate of fifth rectifying column, the feed inlet of sixth rectifying column is connected to the discharge gate of dehydration unit, its characterized in that: and introducing make-up water into the fifth rectifying tower, wherein the make-up water is added from the feed inlet of the fifth rectifying tower or a make-up water inlet is arranged on the fifth rectifying tower.
The feed materials are methanol, formaldehyde, water, trioxymethylene and PODE2The method for supplementing water and separating PODEN is introduced into a rectifying tower of the mixture, and the flow is as follows: the PODEN raw material enters a first rectifying tower, and methyl formate, methylal, methanol, water, formaldehyde, trioxymethylene and PODE are extracted from the top of the first rectifying tower2The mixed materials of (1); the material at the bottom of the first rectifying tower enters a second rectifying tower, and PODE is extracted from the top of the second rectifying tower3-5The material and the tower bottom are PODE6-10The material (2); feeding the material at the top of the first rectifying tower into a third rectifying tower, and extracting a mixed material of methyl formate, methylal and methanol from the top of the third rectifying tower; medicine for treating hepatitis BFeeding the material at the top of the distillation tower into a fourth distillation tower, wherein the material of methyl formate is extracted at the top of the fourth distillation tower, and the mixed material of methylal and methanol is extracted at the bottom of the fourth distillation tower; feeding the tower bottom material of the third rectifying tower into a fifth rectifying tower, introducing make-up water into the fifth rectifying tower, and collecting a mixed material of a formaldehyde water solution and trioxymethylene from the tower bottom of the fifth rectifying tower; feeding the tower top material of the fifth rectifying tower into a dehydration unit, and removing water; the material after water removal enters a sixth rectifying tower, the material of methanol is extracted from the top of the sixth rectifying tower, and PODE is extracted from the tower bottom2The material of (3). The operating pressure of the first rectifying tower is 80-120KPa, the operating temperature of the tower top is 70-100 ℃, the operating pressure of the second rectifying tower is 1-50KPa, the operating temperature of the tower top is 50-150 ℃, the operating pressure of the third rectifying tower is 100-200KPa, the operating temperature of the tower top is 35-70 ℃, the operating pressure of the fourth rectifying tower is 100-200KPa, the operating temperature of the tower top is 30-60 ℃, the operating pressure of the fifth rectifying tower is 80-120KPa, the operating temperature of the tower top is 70-120 ℃, the mass ratio of the content of the supplementary water to the material is 0.3: 1-1: 1, the operating pressure of the sixth rectifying tower is 100-200KPa, and the operating temperature of the tower top is 60-90 ℃.
The feed materials are methanol, formaldehyde, water, trioxymethylene and PODE2The rectifying column of mixture introduces supplementary water separation PODEN's device, including six rectifying columns and a dehydration unit, the top of the tower export of first rectifying column passes through the feed inlet of tube coupling third rectifying column, the feed inlet of tube coupling second rectifying column is passed through in the tower cauldron export of first rectifying column, the feed inlet of tube coupling fourth rectifying column is passed through in the tower cauldron export of third rectifying column, the feed inlet of tube coupling fifth rectifying column is passed through in the tower cauldron export of fourth rectifying column, the feed inlet of dehydration unit is connected to the top of the tower discharge gate of fifth rectifying column, the feed inlet of sixth rectifying column is connected to the discharge gate of dehydration unit, its characterized in that: and introducing make-up water into the fifth rectifying tower, wherein the make-up water is added from the feed inlet of the fifth rectifying tower or a make-up water inlet is arranged on the fifth rectifying tower.
The raw materials include methanol, formaldehyde, water, trioxymethylene and PODE2The method for supplementing water and separating PODEN is introduced into a rectifying tower of the mixture, and the flow is as follows: PODEN raw material enters the first stepA rectifying tower, wherein methyl formate, methylal, methanol, water, formaldehyde, trioxymethylene and PODE are extracted from the top of the rectifying tower2The mixed materials of (1); the material at the bottom of the first rectifying tower enters a second rectifying tower, and PODE is extracted from the top of the second rectifying tower3-5The material and the extraction from the tower bottom are PODE6-10The material (2); feeding the material at the top of the first rectifying tower into a third rectifying tower, and extracting the material which is methyl formate at the top of the third rectifying tower; the tower bottom material of the third rectifying tower enters a fourth rectifying tower, and a mixed material of methylal and methanol is extracted from the tower top of the fourth rectifying tower; feeding the tower bottom material of the fourth rectifying tower into a fifth rectifying tower, introducing make-up water into the fifth rectifying tower, and collecting a mixed material of a formaldehyde water solution and trioxymethylene from the tower bottom of the fifth rectifying tower; the material at the top of the fifth rectifying tower enters a dehydration unit, and the moisture is removed; the material after water removal enters a sixth rectifying tower, the material of methanol is extracted from the tower top of the sixth rectifying tower, and PODE is extracted from the tower bottom2The material of (1). The operating pressure of the first rectifying tower is 80-120KPa, the operating temperature of the tower top is 70-100 ℃, the operating pressure of the second rectifying tower is 1-50KPa, the operating temperature of the tower top is 50-150 ℃, the operating pressure of the third rectifying tower is 100-200KPa, the operating temperature of the tower top is 30-60 ℃, the operating pressure of the fourth rectifying tower is 100-200KPa, the operating temperature of the tower top is 35-70 ℃, the operating pressure of the fifth rectifying tower is 80-120KPa, the operating temperature of the tower top is 70-120 ℃, the mass ratio of the make-up water content to the materials by weight is 0.3: 1-1: 1, the operating pressure of the sixth rectifying tower is 100-200KPa, and the operating temperature of the tower top is 60-90 ℃.
The dehydration unit comprises membrane dehydration, molecular sieve dehydration and adsorption dehydration.
The invention has the following beneficial effects:
the invention provides a method for synthesizing polyoxymethylene dimethyl ethers (PODEN) by using methanol and formaldehyde aqueous solution as raw materials, aiming at the technical current situation that the components of the product are complex, formaldehyde is easy to polymerize in the rectification separation process, and unreacted raw materials need to be respectively recovered2The method and the device for realizing the separation and the refining of the polymethoxy dimethyl ether by introducing the make-up water into the rectifying tower of the mixture have the following unique points:
1. other intermediate components such as methylal and the like and formaldehyde are discharged together, so that the concentration of easily-polymerized substances such as hemiacetal, methylene glycol and the like is reduced, the pipeline is prevented from being blocked by polymerization, and the use continuity of equipment is improved.
2. Through introducing make-up water, the aqueous solution that contains formaldehyde is adopted to the tower bottom, prevents that formaldehyde polymerization from blockking up condenser and pipeline, improves equipment and uses the continuity, and the aqueous solution that contains formaldehyde of retrieving simultaneously can return to formaldehyde and the synthetic reaction unit of methyl acetal of methyl alcohol catalysis, and the material utilization ratio is improved to the reasonable recovery unreacted.
3. By feeding methanol, formaldehyde, water, trioxymethylene and PODE2Make-up water is introduced into the rectifying tower of the mixture, and part of light component materials only need to be heated and distilled once, so that the energy consumption is low.
Drawings
FIG. 1 is a schematic flow diagram of the separation process of example 1;
FIG. 2 is a schematic flow diagram of the separation process of example 2;
FIG. 3 is a schematic flow diagram of the separation process of example 3.
Detailed Description
The present invention will be described in further detail with reference to the following embodiments, which are illustrative only and not limiting, and the scope of the present invention is not limited thereby.
Example 1
In the figure 1, 1-A is a first rectifying tower, 1-B is a second rectifying tower, 1-C is a third rectifying tower, 1-D is a fourth rectifying tower, 1-E is a fifth rectifying tower, 1-F is a dehydration unit, and 1-G is a sixth rectifying tower.
The tower kettle outlet of the first rectifying tower 1-A is connected with the feed inlet of the second rectifying tower 1-B through a pipeline, the tower top outlet of the second rectifying tower 1-B is connected with the feed inlet of the fourth rectifying tower 1-D through a pipeline, the tower kettle outlet of the second rectifying tower 1-B is connected with the feed inlet of the third rectifying tower 1-C through a pipeline, the tower kettle discharge port of the fourth rectifying tower 1-D is connected with the feed inlet of the fifth rectifying tower 1-E, the tower top discharge port of the fifth rectifying tower 1-E is connected with the feed inlet of the dehydration unit 1-F through a pipeline, and the discharge port of the dehydration unit 1-F is connected with the feed inlet of the sixth rectifying tower 1-G.
Make-up water can enter the fifth rectifying tower 1-E together with the tower bottom discharge of the fourth rectifying tower 1-D, or be added separately, if the make-up water is added separately, a make-up water feed inlet is additionally arranged on the fifth rectifying tower 1-E.
1-1 of material is PODEN raw material to be refined, 1-2 of material is methyl formate, 1-3 of material to be refined is raw material containing no methyl formate, 1-4 of material is methylal, methanol, water, formaldehyde, trioxymethylene and PODE21-5 is PODE3-101-6 is PODE3-51-7 is PODE6-101-8 is materials of methylal and methanol, 1-9 is materials of methanol, formaldehyde, water, trioxymethylene and PODE21-10 is pure water material, 1-11 is PODE2Water and methanol materials, 1-12 is aqueous solution containing formaldehyde and trioxymethylene, 1-13 is water material, 1-14 is methanol and PODE2Materials, 1-15 are methanol materials, 1-16 are PODE2And (3) feeding.
Feeding the PODEN raw material (1-1) into a first rectifying tower (1-A), and extracting a material (1-2) of methyl formate from the top of the first rectifying tower (1-A); the materials (1-3) at the bottom of the first rectifying tower (1-A) enter a second rectifying tower (1-B), and methylal, methanol, water, formaldehyde, trioxymethylene and PODE are extracted from the top of the second rectifying tower (1-B)2The material (1-4); the tower bottom material (1-5) of the second rectifying tower (1-B) enters a third rectifying tower (1-C), and PODE is extracted from the tower top of the third rectifying tower (1-C)3-5The material (1-6) and the tower bottom are PODE6-10The material (1-7); the material (1-4) at the top of the second rectifying tower (1-B) enters a fourth rectifying tower (1-D), and the material (1-8) of methylal and methanol is extracted from the top of the fourth rectifying tower (1-D); feeding the tower bottom materials (1-9) of the fourth rectifying tower (1-D) into a fifth rectifying tower (1-E), introducing make-up water (1-10) into the fifth rectifying tower (1-E), and extracting a formaldehyde water solution and trioxymethylene materials (1-12) from the tower bottom of the fifth rectifying tower (1-E); materials (1-11) at the top of the fifth rectifying tower (1-E) enter a dehydration unit (1-F), and moisture (1-13) is removed; the materials (1-14) after water removal enter a sixth rectifying tower (1-G), the materials (1-15) of methanol extracted from the tower top and the PODE in the tower bottom2The materials (1-16).
1800t/h PODEN synthesis product mixture, composition as follows:
| numbering | Components | Content% |
| 1 | Formic acid methyl ester | 1.80 |
| 2 | Methylal compound | 36.66 |
| 3 | Methanol | 5.19 |
| 4 | Formaldehyde (formol) | 9.08 |
| 5 | Water (W) | 1.17 |
| 6 | Trioxymethylene | 2.50 |
| 7 | PODE2 | 20.96 |
| 8 | PODE3-5 | 20.03 |
| 9 | PODE6-10 | 2.41 |
The method is adopted for separation according to scheme 1, wherein the operating pressure of a first rectifying tower (1-A) is 100KPa, the operating temperature of the top of the tower is 32 ℃, the operating pressure of a second rectifying tower (1-B) is 80KPa, the operating temperature of the top of the tower is 86 ℃, the operating pressure of a third rectifying tower (1-C) is 1KPa, the operating temperature of the top of the tower is 52 ℃, the operating pressure of a fourth rectifying tower (1-D) is 100KPa, the operating temperature of the top of the tower is 40 ℃, the operating pressure of a fifth rectifying tower (1-E) is 80KPa, the mass ratio of the content of make-up water (1-10) to the content of materials (1-9) is 0.3:1, the operating temperature of the top of the tower is 76 ℃, a dehydration unit (1-F) adopts a molecular sieve for dehydration, the operating pressure of a sixth rectifying tower (1-G) is 100KPa, and the operating temperature of the top of the tower is 64 ℃.
Separating to obtain 32t/h of PODE (dimethyl Formate), 670t/h and 377t/h of methyl formate, methylal and methanol materials2PODE of 360t/h3-5Qualified products and the formaldehyde water solution with the mass fraction of about 50 percent of 327t/h are recovered.
Example 2
In FIG. 2, 2-A is a first rectifying tower, 2-B is a second rectifying tower, 2-C is a third rectifying tower, 2-D is a fourth rectifying tower, 2-E is a fifth rectifying tower, 2-F is a dehydration unit, and 2-G is a sixth rectifying tower;
the top outlet of the first rectifying tower 2-A is connected with the feed inlet of a third rectifying tower 2-C through a pipeline, the bottom outlet of the first rectifying tower 2-A is connected with the feed inlet of a second rectifying tower 2-B through a pipeline, the top outlet of the third rectifying tower 2-C is connected with the feed inlet of a fourth rectifying tower 2-D through a pipeline, the bottom outlet of the third rectifying tower 2-C is connected with the feed inlet of a fifth rectifying tower 2-E through a pipeline, the top outlet of the fifth rectifying tower 2-E is connected with the feed inlet of a dehydration unit 2-F, and the outlet of the dehydration unit 2-F is connected with the feed inlet of a sixth rectifying tower 2-G.
The make-up water can enter the fifth rectifying tower 2-E together with the tower bottom discharge of the third rectifying tower 2-C, or can be added independently, if the make-up water is added independently, a make-up water feeding port is additionally arranged on the fifth rectifying tower 2-E.
The material 2-1 is PODEN to-be-refined raw material, and the material 2-2 is PODE-free3-102-3 is PODE3-102-4 is PODE3-52-5 is PODE6-102-6 is methyl formate, methylal and methanol, 2-7 is methanol, water, formaldehyde, trioxymethylene and PODE22-8 is methyl formate, 2-9 is methylal and methanol, 2-10 is pure water, 2-11 is PODE2Water and methanol, 2-12 is formaldehyde aqueous solution and trioxymethylene material, 2-13 is water material, 2-14 is methanol and PODE2Materials 2-15 are methanol materials, 2-16 are PODE2And (3) feeding.
PODEN raw material (2-1) enters a first rectifying tower (2-A), and methyl formate, methylal, methanol, water, formaldehyde, trioxymethylene and PODE are extracted from the top of the first rectifying tower (2-A)2The material (2-2); the material (2-3) at the bottom of the first rectifying tower (2-A) enters a second rectifying tower (2-B), and PODE (potassium iodide) is basically extracted from the top of the second rectifying tower (2-B)3-5The material (2-4) and the bottom of the column are basically PODE6-102-5); the material (2-2) at the top of the first rectifying tower (2-A) enters a third rectifying tower (2-C), and the material (2-6) which is basically methyl formate, methylal and methanol is extracted from the top of the third rectifying tower (2-C); feeding the material (2-6) at the top of the third rectifying tower (2-C) into a fourth rectifying tower (2-D), and collecting the material (2-8) of methyl formate at the top of the fourth rectifying tower (2-D) and the material (2-9) of methylal and methanol at the bottom of the fourth rectifying tower (2-D); feeding the tower bottom material (2-7) of the third rectifying tower (2-C) into a fifth rectifying tower (2-E), introducing make-up water (2-10) into the fifth rectifying tower (2-E), and extracting a formaldehyde water solution and a trioxymethylene material (2-12) from the tower bottom of the fifth rectifying tower (2-E); the material (2-11) at the top of the fifth rectifying tower (2-E) enters a dehydration unit (2-F), and the moisture (2-13) is removed; the material (2-14) after water removal enters a sixth rectifying tower (2-G), the material (2-15) of methanol extracted from the tower top and the PODE in the tower bottom22-16.
2400t/h PODEN synthesis product mixture, composition as follows:
| number of | Components | Content% |
| 1 | Formic acid methyl ester | 1.80 |
| 2 | Methylal | 36.66 |
| 3 | Methanol | 5.19 |
| 4 | Formaldehyde (I) | 9.08 |
| 5 | Water (W) | 1.17 |
| 6 | Trioxymethylene | 2.50 |
| 7 | PODE2 | 20.96 |
| 8 | PODE3-5 | 20.03 |
| 9 | PODE6-10 | 2.41 |
By adopting the method scheme 2 for separation, the operating pressure of a first rectifying tower (2-A) is 100KPa, the operating temperature of the top of the tower is 90 ℃, the operating pressure of a second rectifying tower (2-B) is 1KPa, the operating temperature of the top of the tower is 52 ℃, the operating pressure of a third rectifying tower (2-C) is 100KPa, the operating temperature of the top of the tower is 39 ℃, the operating pressure of a fourth rectifying tower (2-D) is 100KPa, the operating temperature of the top of the tower is 32 ℃, the operating pressure of a fifth rectifying tower (2-E) is 100KPa, the mass ratio of the content of the make-up water (2-10) to the material (2-7) is 0.5:1, the operating temperature of the top of the tower is 80 ℃, a dehydration unit (2-F) adopts membrane dehydration, the operating pressure of a sixth rectifying tower (2-G) is 100KPa, and the operating temperature of the top of the tower is 64 ℃.
42t/h of methyl formate, methylal and methanol materials are obtained by separation, wherein 893t/h and 503t/h of PODE are obtained2PODE of 480t/h3-5Qualified products and a formaldehyde water solution with the mass fraction of about 35 percent at 622t/h are recovered.
Example 3
In FIG. 3, 3-A is a first rectifying tower, 3-B is a second rectifying tower, 3-C is a third rectifying tower, 3-D is a fourth rectifying tower, 3-E is a fifth rectifying tower, 3-F is a dehydration unit, and 3-G is a sixth rectifying tower;
the top outlet of the first rectifying tower 3-A is connected with the feed inlet of the third rectifying tower 3-C through a pipeline, the bottom outlet of the first rectifying tower 3-A is connected with the feed inlet of the second rectifying tower 3-B through a pipeline, the bottom outlet of the third rectifying tower 3-C is connected with the feed inlet of the fourth rectifying tower 3-D through a pipeline, the bottom outlet of the fourth rectifying tower 3-D is connected with the feed inlet of the fifth rectifying tower 3-E through a pipeline, the top outlet of the fifth rectifying tower 3-E is connected with the feed inlet of the dehydration unit 3-F, and the outlet of the dehydration unit 3-F is connected with the feed inlet of the sixth rectifying tower 3-G.
The make-up water can enter the fifth rectifying tower 3-E together with the tower bottom discharge of the fourth rectifying tower 3-D, or can be added independently, if the make-up water is added independently, a make-up water feed inlet is additionally arranged on the fifth rectifying tower 3-E.
Material 3-1 is PODEN to be refined, and material 3-2 is PODE-free3-103-3 is PODE3-103-4 is PODE3-53-5 is PODE6-103-6 is methyl formate, 3-7 is methylal, methanol, water, formaldehyde, trioxymethylene and PODE23-8 is the material of methylal and methanol, 3-9 is methanol, water, formaldehyde, trioxymethylene and PODE23-10 is pure water material, 3-11 is PODE2Water and methanol, 3-12 are aqueous formaldehyde solution and trioxymethylene, 3-13 are water, 3-14 are methanol and PODE2Materials, 3-15 are methanol materials, 3-16 are PODE2And (3) feeding.
PODEN raw material (3-1) enters a first rectifying tower (3-A), and methyl formate, methylal, methanol, water, formaldehyde, trioxymethylene and PODE are extracted from the top of the first rectifying tower (3-A)2The material (3-2); the material (3-3) at the bottom of the first rectifying tower (3-A) enters a second rectifying tower (3-B), and PODE is extracted from the top of the second rectifying tower (3-B)3-5The material (3-4) and the tower bottom are PODE6-103-5); the material (3-2) at the top of the first rectifying tower (3-A) enters a third rectifying tower (3-C), and the material (3-6) of methyl formate is extracted from the top of the third rectifying tower (3-C); feeding the tower bottom material (3-7) of the third rectifying tower (3-C) into a fourth rectifying tower (3-D), and extracting a material (3-8) of methylal and methanol from the tower top of the fourth rectifying tower (3-D); feeding the tower bottom material (3-9) of the fourth rectifying tower (3-D) into a fifth rectifying tower (3-E), introducing make-up water (3-10) into the fifth rectifying tower (3-E), and extracting a formaldehyde water solution and a trioxymethylene material (3-12) from the tower bottom of the fifth rectifying tower (3-E); the material (3-11) at the top of the fifth rectifying tower (3-E) enters a dehydration unit (3-F), and the moisture (3-13) is removed; the materials (3-14) after water removal enter a sixth rectifying tower (3-G), and the tower topThe material (3-15) for extracting methanol and the column bottom are PODE23-16.
2700t/h PODEN synthesis product mixture, composition as follows:
| numbering | | Content% | |
| 1 | Formic acid methyl ester | 1.80 | |
| 2 | Methylal | 36.66 | |
| 3 | Methanol | 5.19 | |
| 4 | Formaldehyde (I) | 9.08 | |
| 5 | Water (W) | 1.17 | |
| 6 | Trioxymethylene | 2.50 | |
| 7 | PODE2 | 20.96 | |
| 8 | PODE3-5 | 20.03 | |
| 9 | PODE6-10 | 2.41 |
By adopting the method scheme 3 for separation, the operating pressure of a first rectifying tower (3-A) is 100KPa, the operating temperature of the top of the tower is 90 ℃, the operating pressure of a second rectifying tower (3-B) is 50KPa, the operating temperature of the top of the tower is 144 ℃, the operating pressure of a third rectifying tower (3-C) is 200KPa, the operating temperature of the top of the tower is 51 ℃, the operating pressure of a fourth rectifying tower (3-D) is 200KPa, the operating temperature of the top of the tower is 61 ℃, the operating pressure of a fifth rectifying tower (3-E) is 100KPa, the mass ratio of the content of the make-up water (3-10) to the material (3-9) is 1:1, the operating temperature of the top of the tower is 80 ℃, the dehydrating unit (3-F) adopts adsorption dehydration, the operating pressure of a sixth rectifying tower (3-G) is 100KPa, and the operating temperature of the top of the tower is 64 ℃.
48t/h of methyl formate, methylal and methanol materials 1004t/h and 566t/h of PODE are obtained by separation2PODE of 540t/h3-5Qualified products and the recovered formaldehyde solution with the mass fraction of about 20 percent of 1225 t/h.
The invention provides a method for preparing a catalyst by using methanol, formaldehyde, water, trioxymethylene and PODE as raw materials2The method and apparatus for separating and refining polyoxymethylene dimethyl ethers by introducing make-up water into the distillation column of the mixture have been described with reference to preferred embodiments, and it will be apparent to those skilled in the art that the present technology can be practiced by modifying or appropriately combining the structures and apparatus described herein without departing from the spirit and scope of the invention. It is expressly noted that all such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the scope and spirit of the inventionAre intended to be included within the spirit, scope and content of this invention.
Claims (1)
1. A method for separating and refining polyoxymethylene dimethyl ethers is characterized in that: the polymethoxy dimethyl ether is prepared by taking methanol and formaldehyde aqueous solution as raw materials, wherein the raw materials comprise methanol, formaldehyde, water, trioxymethylene and PODE2Make-up water is introduced into the rectifying tower of the mixture, and the aqueous solution of formaldehyde and trioxymethylene are extracted from the tower kettle, so that the aim of separating formaldehyde and trioxymethylene is fulfilled;
the method specifically comprises three parallel technical schemes:
the first scheme is as follows: adopting six-stage rectification, comprising six rectification towers and a dehydration unit, wherein PODEN raw material enters a first rectification tower, and a material of methyl formate is extracted from the top of the first rectification tower; the material at the bottom of the first rectifying tower enters a second rectifying tower, and methylal, methanol, water, formaldehyde, trioxymethylene and PODE are extracted from the top of the second rectifying tower2The mixed materials of (1); the material at the bottom of the second rectifying tower enters a third rectifying tower, and PODE is extracted from the top of the third rectifying tower3-5The material and the tower bottom are PODE6-10The material (c); the material at the top of the second rectifying tower enters a fourth rectifying tower, and the material of methylal and methanol is extracted from the top of the fourth rectifying tower; feeding the material in the tower bottom of the fourth rectifying tower into a fifth rectifying tower, introducing make-up water into the fifth rectifying tower, wherein the mass ratio of the added amount of the make-up water to the fed material is 0.3: 1-1: 1 by weight, and the material of aqueous formaldehyde solution and trioxymethylene is extracted from the tower bottom of the fifth rectifying tower; the material at the top of the fifth rectifying tower enters a dehydration unit, the material after water removal enters a sixth rectifying tower, the material which is methanol is extracted from the top of the sixth rectifying tower, and PODE is extracted from the tower bottom2The material (2); the operation pressure of the first rectifying tower is 100-200KPa, the operation temperature of the tower top is 30-60 ℃, the operation pressure of the second rectifying tower is 80-120KPa, the operation temperature of the tower top is 70-100 ℃, the operation pressure of the third rectifying tower is 1-50KPa, the operation temperature of the tower top is 50-150 ℃, the operation pressure of the fourth rectifying tower is 100-200KPa, the operation temperature of the tower top is 35-70 ℃, the operation pressure of the fifth rectifying tower is 80-120KPa, the operation temperature of the tower top is 70-120 ℃, and the content of the supplementary water and the material are calculated by weightThe mass ratio is 0.3: 1-1: 1, the operation pressure of the sixth rectifying tower is 100-200KPa, and the operation temperature of the tower top is 60-90 ℃;
scheme two is as follows: six-stage rectification is adopted, the six-stage rectification comprises six rectification towers and a dehydration unit, PODEN raw material enters a first rectification tower, and methyl formate, methylal, methanol, water, formaldehyde, trioxymethylene and PODE are extracted from the top of the first rectification tower2The mixed materials of (1); the material at the bottom of the first rectifying tower enters a second rectifying tower, and PODE is extracted from the top of the second rectifying tower3-5The material and the tower bottom are PODE6-10The material (2); feeding the material at the top of the first rectifying tower into a third rectifying tower, and extracting a mixed material of methyl formate, methylal and methanol from the top of the third rectifying tower; feeding the material at the top of the third rectifying tower into a fourth rectifying tower, and extracting a material of methyl formate at the top of the fourth rectifying tower and a mixed material of methylal and methanol at the bottom of the fourth rectifying tower; feeding the material in the tower bottom of the third rectifying tower into a fifth rectifying tower, introducing make-up water into the fifth rectifying tower, wherein the mass ratio of the addition amount of the make-up water to the feeding amount is 0.3: 1-1: 1, and the material in the tower bottom of the fifth rectifying tower is a mixed material of aqueous formaldehyde solution and trioxymethylene; the material at the top of the fifth rectifying tower enters a dehydration unit, the material after water removal enters a sixth rectifying tower, the material of methanol is extracted from the top of the sixth rectifying tower, and PODE is adopted at the tower bottom2The material (2); the operating pressure of the first rectifying tower is 80-120KPa, the operating temperature of the tower top is 70-100 ℃, the operating pressure of the second rectifying tower is 1-50KPa, the operating temperature of the tower top is 50-150 ℃, the operating pressure of the third rectifying tower is 100-200KPa, the operating temperature of the tower top is 35-70 ℃, the operating pressure of the fourth rectifying tower is 100-200KPa, the operating temperature of the tower top is 30-60 ℃, the operating pressure of the fifth rectifying tower is 80-120KPa, the operating temperature of the tower top is 70-120 ℃, the mass ratio of the content of the supplementary water to the material is 0.3: 1-1: 1, the operating pressure of the sixth rectifying tower is 100-200KPa, and the operating temperature of the tower top is 60-90 ℃;
the third scheme is as follows: six-stage rectification is adopted, the six-stage rectification comprises six rectification towers and a dehydration unit, PODEN raw material enters a first rectification tower, and methyl formate, methylal, methanol, water, formaldehyde, trioxymethylene and PODE are extracted from the top of the first rectification tower2The mixed materials of (1); first of allThe material at the bottom of the rectifying tower enters a second rectifying tower, and PODE is extracted from the top of the second rectifying tower3-5The material and the extraction from the tower bottom are PODE6-10The material (2); feeding the material at the top of the first rectifying tower into a third rectifying tower, and extracting the material which is methyl formate at the top of the third rectifying tower; the tower bottom material of the third rectifying tower enters a fourth rectifying tower, and a mixed material of methylal and methanol is extracted from the tower top of the fourth rectifying tower; feeding the tower bottom material of the fourth rectifying tower into a fifth rectifying tower, introducing make-up water into the fifth rectifying tower, wherein the mass ratio of the added amount of the make-up water to the fed material is 0.3: 1-1: 1 by weight, and the tower bottom material of the fifth rectifying tower is a mixed material of aqueous formaldehyde solution and trioxymethylene; the material at the top of the fifth rectifying tower enters a dehydration unit, and the moisture is removed; the material after water removal enters a sixth rectifying tower, the material of methanol is extracted from the tower top of the sixth rectifying tower, and PODE is extracted from the tower bottom2The material (2); the operating pressure of the first rectifying tower is 80-120KPa, the operating temperature of the tower top is 70-100 ℃, the operating pressure of the second rectifying tower is 1-50KPa, the operating temperature of the tower top is 50-150 ℃, the operating pressure of the third rectifying tower is 100-200KPa, the operating temperature of the tower top is 30-60 ℃, the operating pressure of the fourth rectifying tower is 100-200KPa, the operating temperature of the tower top is 35-70 ℃, the operating pressure of the fifth rectifying tower is 80-120KPa, the operating temperature of the tower top is 70-120 ℃, the mass ratio of the content of the supplementary water to the material is 0.3: 1-1: 1, the operating pressure of the sixth rectifying tower is 100-200KPa, and the operating temperature of the tower top is 60-90 ℃.
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