Method for producing isosorbide and co-producing methanol

Abstract

The invention relates to a method for producing isosorbide and co-producing methanol, which comprises the following steps: a, carrying out contact reaction rectification on a dimethyl carbonate raw material and a sorbitol raw material to obtain methanol, dimethyl carbonate and methanol azeotrope and other product flows; and b, carrying out reduced pressure rectification on other product flows to obtain isosorbide, unreacted sorbitol and a heavy component intermediate product flow. According to the method, the dimethyl carbonate raw material is contacted with the sorbitol raw material, and the high-purity isosorbide and the high-purity methanol can be co-produced by sequentially carrying out reactive distillation and vacuum distillation.

Description

Technical Field

[0001] The present invention relates to a method for producing isosorbide and co-producing methanol. Background Art

[0002] Isosorbide is a new type of bio-based material, which is widely used in medicine, polymer materials, polymer modification, electronics and other fields. Isosorbide can be obtained by secondary dehydration of sorbitol. The reaction of sorbitol dehydration to prepare isosorbide mostly uses acidic catalysts such as liquid acids such as sulfuric acid, phosphoric acid and hydrochloric acid, but strong acids will seriously corrode equipment and are not environmentally friendly.

[0003] CN 103980286A discloses a method for preparing isosorbide, using polyphosphoric acid as a catalyst, sorbitol and water form a gaseous mixture under high temperature reaction conditions, and then condensing isosorbide and water in sequence to obtain isosorbide. When liquid acid is used as a catalyst, although the reaction efficiency is high, it is difficult to separate the catalyst from the raw materials and products, and the equipment is severely corroded. Sorbitol and dimethyl carbonate can react at a lower temperature under the action of a resin catalyst to generate isosorbide, methanol and carbon dioxide. The above reaction solves the problems of high temperature and strong acid, but the reaction is a reversible reaction, and a series of heavy component intermediates such as methyl sorbitol carbonate, 1,4-anhydrosorbitol, and methyl 1,4-anhydrosorbitol carbonate will be generated, and sorbitol and isosorbide also have high boiling points, and the conventional method for reaction and refining has high energy consumption. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of the prior art that the isosorbide preparation product is difficult to separate, there are many by-products, the cost is high, the reactant conversion rate is low, and the energy consumption is high, and a method for producing isosorbide and co-producing methanol is provided, wherein the method can obtain high-purity isosorbide and methanol.

[0005] In order to achieve the above object, the present invention provides a method for producing isosorbide and co-producing methanol, the method comprising:

[0006] a. contacting a dimethyl carbonate raw material with a sorbitol raw material for reaction and distillation to obtain methanol, dimethyl carbonate and methanol azeotrope and other product streams;

[0007] b. The other product streams are subjected to vacuum distillation to obtain isosorbide, unreacted sorbitol and a heavy component intermediate product stream.

[0008] Through the above technical solution, the present invention has the following beneficial effects:

[0009] The present invention contacts a dimethyl carbonate raw material with a sorbitol raw material, and sequentially performs reactive distillation and vacuum distillation to obtain high-purity isosorbide and simultaneously co-produce high-purity methanol. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a combined process flow chart of a reactive distillation dividing wall tower and a vacuum distillation dividing wall tower of the present invention;

[0011] Figure 2 It is a process flow chart of the combination of a common reaction distillation tower and a common vacuum distillation tower. DETAILED DESCRIPTION

[0012] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0013] In the present invention, unless otherwise specified, directional words such as "top" generally refer to the 0-10% volume portion from top to bottom of the container, "bottom" refers to the 90-100% volume portion from top to bottom of the container, "upper part" refers to the 10-40% volume portion from top to bottom of the container, "middle / section" refers to the 40-60% volume portion from top to bottom of the container, and "lower part" refers to the 60-90% volume portion from top to bottom of the container.

[0014] The present invention provides a method for producing isosorbide and co-producing methanol, the method comprising:

[0015] a. contacting a dimethyl carbonate raw material with a sorbitol raw material, and performing reactive distillation to obtain methanol, dimethyl carbonate and methanol azeotrope and other product streams;

[0016] b. The other product streams are subjected to vacuum distillation to obtain isosorbide, unreacted sorbitol and a heavy component intermediate product stream.

[0017] The present invention contacts a dimethyl carbonate raw material with a sorbitol raw material, and sequentially performs reactive distillation and vacuum distillation to obtain high-purity isosorbide and simultaneously co-produce high-purity methanol.

[0018] In the present invention, the product stream of the reactive distillation further includes a carbon dioxide gas stream.

[0019] According to a preferred embodiment of the present invention, the heavy component intermediate product stream mainly comprises: methyl sorbitol carbonate, 1,4-anhydrosorbitan, and methyl 1,4-anhydrosorbitan carbonate.

[0020] In the present invention, as long as the purpose of the present invention can be achieved, there is no particular requirement for the type of the dimethyl carbonate raw material. According to a preferred embodiment of the present invention, the dimethyl carbonate raw material is selected from dimethyl carbonate or a mixture of dimethyl carbonate and methanol, preferably a mixture of dimethyl carbonate and methanol. By adopting the aforementioned scheme of adding methanol, the purity of isosorbide can be further improved.

[0021] According to a preferred embodiment of the present invention, the molar content of dimethyl carbonate in the mixture of dimethyl carbonate and methanol is 0.14-0.25. By adopting the above preferred embodiment, the purity of isosorbide and methanol can be further improved.

[0022] According to a preferred embodiment of the present invention, the mixture of dimethyl carbonate and methanol comes from at least one of the processes of reacting ethylene carbonate with methanol to produce ethylene glycol and dimethyl carbonate (i.e., alcoholysis of ethylene carbonate) and reacting phenol with dimethyl carbonate to produce diphenyl carbonate (diphenyl carbonate process).

[0023] In the present invention, there is no special requirement for the method of reactive distillation, for example, the reaction and distillation may be carried out simultaneously, the reaction may be carried out first and then distillation may be carried out, or the crude fraction may be carried out after the reaction and then distillation may be carried out. According to a preferred embodiment of the present invention, the reactive distillation includes a reactive crude distillation stage and a first distillation stage along the logistics direction. By adopting the above preferred embodiment, the purity of isosorbide and methanol can be further improved.

[0024] In the present invention, there is no particular requirement for the vacuum distillation method. According to a preferred embodiment of the present invention, the vacuum distillation includes a pre-fractionation stage and a second distillation stage along the direction of the flow. By adopting the above preferred embodiment, the purity of isosorbide and methanol can be further improved.

[0025] According to a preferred embodiment of the present invention, in step a, the dimethyl carbonate and methanol azeotrope is recycled back to the dimethyl carbonate raw material. By adopting the above preferred embodiment, the purity of isosorbide and methanol can be further improved.

[0026] According to a preferred embodiment of the present invention, in step b, the unreacted sorbitol is recycled back to the sorbitol raw material. By adopting the above preferred embodiment, the purity of isosorbide and methanol can be further improved.

[0027] In the present invention, there is no special requirement for the device for performing the reactive distillation. According to a preferred embodiment of the present invention, the reactive distillation is performed in a reactive distillation bulkhead tower comprising a reaction sub-tower and a distillation main tower. The specific process flow includes:

[0028] The dimethyl carbonate raw material and the sorbitol raw material are contacted and reacted in the reaction sub-tower, and the obtained first gas phase product and the first liquid phase product are passed into the main distillation tower for distillation separation to obtain methanol, dimethyl carbonate and methanol azeotrope and other product streams. By adopting the above preferred embodiment, the purity of isosorbide and methanol can be further improved.

[0029] According to a preferred embodiment of the present invention, the specific process flow of the reactive distillation includes: dimethyl carbonate raw material is fed at the 15th to 55th theoretical plates of the reaction sub-tower, sorbitol raw material is fed at the 5th to 20th theoretical plates of the reaction sub-tower, the first gas phase product is fed at the 6th to 16th theoretical plates of the rectification main tower, the first liquid phase product is fed at the 26th to 86th theoretical plates of the rectification main tower, methanol is discharged at the 15th to 55th theoretical plates of the rectification main tower, dimethyl carbonate and methanol azeotrope is discharged at the top of the rectification main tower, and other product streams are discharged at the bottom of the rectification main tower. By adopting the above preferred scheme, the purity of isosorbide and methanol can be further improved.

[0030] According to a preferred embodiment of the present invention, the specific process flow of the reactive distillation further includes discharging the carbon dioxide gas stream at the top of the main distillation tower.

[0031] According to a preferred embodiment of the present invention, the main distillation tower also separates a gas phase mixture and / or a liquid phase mixture of methanol and dimethyl carbonate, and recycles the mixture back to the reaction tower. By adopting the above preferred embodiment, the purity of isosorbide and methanol can be further improved.

[0032] According to a preferred embodiment of the present invention, the liquid phase mixture of methanol and dimethyl carbonate is discharged from the 5th to 15th theoretical plates of the main distillation tower and circulated back to the top of the reaction tower, and the gas phase mixture of methanol and dimethyl carbonate is discharged from the 26th to 86th theoretical plates of the main distillation tower and circulated back to the bottom of the reaction tower. By adopting the above preferred scheme, the purity of isosorbide and methanol can be further improved.

[0033] In the present invention, there is no special requirement for the device for vacuum distillation. According to a preferred embodiment of the present invention, the vacuum distillation is carried out in a vacuum distillation bulkhead tower comprising a pre-fractionation sub-tower and a distillation main tower. The specific process flow includes:

[0034] The other product streams are roughly separated in the pre-fractionation sub-tower, and the obtained second gas phase product and second liquid phase product are introduced into the main distillation tower for distillation separation to obtain isosorbide, unreacted sorbitol and heavy component intermediate product stream. By adopting the above preferred scheme, the purity of isosorbide and methanol can be further improved.

[0035] According to a preferred embodiment of the present invention, the specific process flow of the vacuum distillation includes: other product streams are fed to the 10th to 40th theoretical plates of the pre-fractionation sub-tower, the second gas phase product is fed to the 6th to 16th theoretical plates of the distillation main tower, the first liquid phase product is fed to the 26th to 86th theoretical plates of the distillation main tower, isosorbide is discharged from the 15th to 60th theoretical plates of the distillation main tower, unreacted sorbitol is discharged from the top of the distillation main tower, and the heavy component intermediate product stream is discharged from the bottom of the distillation main tower. By adopting the above preferred scheme, the purity of isosorbide and methanol can be further improved.

[0036] According to a preferred embodiment of the present invention, the main distillation tower also separates a gas phase mixture and / or a liquid phase mixture of sorbitol and isosorbide, and circulates it back to the pre-fractionation tower. By adopting the above preferred scheme, the purity of isosorbide and methanol can be further improved.

[0037] According to a preferred embodiment of the present invention, the liquid phase mixture of sorbitol and isosorbide is discharged from the 5th to 15th theoretical plates of the main distillation tower and circulated back to the top of the reaction tower, and the gas phase mixture of sorbitol and isosorbide is discharged from the 26th to 86th theoretical plates of the main distillation tower and circulated back to the bottom of the reaction tower. By adopting the above preferred scheme, the purity of isosorbide and methanol can be further improved.

[0038] According to a preferred embodiment of the present invention, the number of theoretical plates of the main distillation tower in the reactive distillation dividing wall tower is 30-100, the tower top operating pressure is 10-100 kPa, the tower top operating temperature is 13.2-64° C., and the tower bottom operating temperature is 60-160° C. By adopting the above preferred scheme, the purity of isosorbide and methanol can be further improved.

[0039] According to a preferred embodiment of the present invention, the number of theoretical plates of the reaction sub-tower in the reactive distillation dividing wall tower is 20-70, the tower top operating pressure is 10-100 kPa, the tower top operating temperature is 18-70° C., and the tower bottom operating temperature is 50-140° C. By adopting the above preferred scheme, the purity of isosorbide and methanol can be further improved.

[0040] According to a preferred embodiment of the present invention, the number of theoretical plates of the main distillation tower in the vacuum distillation dividing wall tower is 30-100, the tower top operating pressure is 0.1-30 kPa, the tower top operating temperature is 70-200° C., and the tower bottom operating temperature is 160-350° C. By adopting the above preferred scheme, the purity of isosorbide and methanol can be further improved.

[0041] According to a preferred embodiment of the present invention, the number of theoretical plates of the pre-fractionation sub-tower in the vacuum distillation dividing wall tower is 20-70, the tower top operating pressure is 0.1-30 kPa, the tower top operating temperature is 85-220° C., and the tower bottom operating temperature is 140-320° C. By adopting the above preferred scheme, the purity of isosorbide and methanol can be further improved.

[0042] According to a preferred embodiment of the present invention, the contacting is carried out in the presence of a catalyst, and the catalyst is preferably selected from a homogeneous acid-base catalyst and / or a heterogeneous acid-base catalyst.

[0043] According to a preferred embodiment of the present invention, the contacting conditions include: the molar ratio of the dimethyl carbonate raw material calculated as dimethyl carbonate to the sorbitol raw material calculated as sorbitol is 1-50, preferably 10-30.

[0044] According to a preferred embodiment of the present invention, the conditions of the reactive distillation include: the tower top temperature is 13.2-70°C, preferably 46.3-64°C; the pressure is 10-100 kPa, preferably 50-100 kPa.

[0045] According to a preferred embodiment of the present invention, the conditions of the vacuum distillation include: the tower top temperature is 70-220°C, preferably 70-160°C; the pressure is 0.1-30kPa, 0.1-10kPa.

[0046] The present invention provides a device for producing isosorbide and co-producing methanol, such as Figure 1 , the device comprises:

[0047] A reaction distillation dividing wall tower composed of a reaction sub-tower and a distillation main tower, and a vacuum distillation dividing wall tower composed of a pre-fractionation sub-tower and a distillation main tower;

[0048] The upper part of the reaction sub-tower of the reaction distillation dividing wall tower is provided with a sorbitol raw material inlet and a gas phase product outlet connected to the upper part of the rectification main tower of the reaction distillation dividing wall tower, and the lower part is provided with a dimethyl carbonate raw material inlet and a liquid phase product outlet connected to the lower part of the rectification main tower of the reaction distillation dividing wall tower; the top of the rectification main tower of the reaction distillation dividing wall tower is provided with a dimethyl carbonate and methanol azeotrope outlet connected to the dimethyl carbonate raw material inlet of the reaction sub-tower and a carbon dioxide gas stream outlet, the upper part is provided with a liquid phase product outlet connected to the top of the reaction sub-tower of the reaction distillation dividing wall tower, the middle part is provided with a methanol outlet, the lower part is provided with a gas phase product outlet connected to the bottom of the reaction sub-tower of the reaction distillation dividing wall tower, and other product stream outlets are provided at the bottom;

[0049] A feed inlet connected to other product flow outlets at the bottom of the main distillation tower of the reactive distillation bulkhead tower is arranged in the middle of the pre-fractionation tower of the vacuum distillation bulkhead tower, a liquid product outlet is arranged at the lower part, and a gas phase outlet is arranged at the upper part; an unreacted sorbitol outlet connected to the sorbitol raw material inlet arranged at the upper part of the reaction sub-tower of the reactive distillation bulkhead tower is arranged at the top of the main distillation tower of the vacuum distillation bulkhead tower, a liquid product outlet connected to the top of the pre-fractionation tower of the vacuum distillation bulkhead tower is arranged at the upper part, an isosorbide outlet is arranged in the middle, a gas product outlet connected to the bottom of the pre-fractionation tower of the vacuum distillation bulkhead tower is arranged at the lower part, and a heavy component intermediate product flow outlet is arranged at the bottom.

[0050] The process includes:

[0051] The dimethyl carbonate raw material enters from the middle of the reaction tower, and the sorbitol raw material enters from the upper part of the reaction tower, and the obtained gaseous products (including methanol and unreacted dimethyl carbonate) enter the upper part of the main distillation tower of the reaction distillation dividing wall tower, and the liquid products (including sorbitol, isosorbide, heavy component intermediate products and methanol) obtained from the main distillation tower of the reaction distillation dividing wall tower enter the lower part of the main distillation tower of the reaction distillation dividing wall tower, and methanol is extracted from the middle section of the main distillation tower of the reaction distillation dividing wall tower. The unreacted dimethyl carbonate and The methanol azeotrope is circulated back to the top of the reaction sub-tower to continue to participate in the reaction, the carbon dioxide gas stream is discharged from the top of the main distillation tower, the liquid phase product (including methanol and dimethyl carbonate) produced in the upper part of the main distillation tower of the reaction distillation dividing wall tower is circulated back to the top of the reaction sub-tower, the gas phase product (including methanol and dimethyl carbonate) produced in the lower part of the main distillation tower of the reaction distillation dividing wall tower is circulated back to the bottom of the reaction sub-tower, and the bottom product of the main distillation tower of the reaction distillation dividing wall tower enters from the middle section of the pre-fractionation tower of the vacuum distillation dividing wall tower;

[0052] The gaseous product (including sorbitol and isosorbide) obtained by the pre-fractionation tower of the vacuum distillation dividing wall tower enters the upper part of the main distillation tower of the vacuum distillation dividing wall tower, and the obtained liquid product (including isosorbide and heavy component intermediate product) enters the lower part of the main distillation tower of the vacuum distillation dividing wall tower. The isosorbide product is extracted from the middle section of the main distillation tower of the vacuum distillation dividing wall tower. The liquid product (including isosorbide and sorbitol) produced from the upper part of the main distillation tower of the vacuum distillation dividing wall tower is circulated back to the top of the pre-fractionation tower, and the gaseous product (including isosorbide and sorbitol) produced from the lower part of the main distillation tower of the vacuum distillation dividing wall tower is circulated back to the bottom of the reaction sub-tower, and the heavy component intermediate product is extracted from the bottom of the main distillation tower of the vacuum distillation dividing wall tower.

[0053] Main reaction:

[0054]

[0055] The present invention will be described in detail below through examples. In the following examples, the purity parameters are measured by gas chromatography, and the examples and comparative examples of the present application are all implemented using the same heterogeneous acid-base catalyst.

[0056] Example 1

[0057] according to Figure 1 The process flow shown in the figure is as follows: the main distillation tower of the reactive distillation dividing wall tower has 60 theoretical plates, the tower top operating pressure is 100 kPa, the tower top operating temperature is 63.7°C, and the tower bottom operating temperature is 160.1°C; the reactive auxiliary tower has 45 theoretical plates, the tower top operating pressure is 100 kPa, the tower top operating temperature is 70.2°C, and the tower bottom operating temperature is 138.9°C; the dimethyl carbonate and methanol azeotrope raw material (from the ethylene carbonate alcoholysis process, the content of dimethyl carbonate is 30%) is in the reaction Feed the material at the 30th theoretical plate of the auxiliary tower, and feed the sorbitol raw material at the 12th theoretical plate of the reaction auxiliary tower; the molar ratio of dimethyl carbonate and methanol azeotrope (calculated as dimethyl carbonate (the same below) to sorbitol is 15.2; the liquid phase is extracted from the 8th plate of the main distillation tower to the top of the reaction auxiliary tower, and the steam at the top of the reaction auxiliary tower returns to the 9th theoretical plate of the main distillation tower. The steam at the bottom of the main distillation tower enters the bottom of the reaction auxiliary tower from the 50th plate, and the liquid phase at the bottom of the reaction auxiliary tower returns to the 50th plate of the lower part of the main distillation tower. The methanol product with a mass fraction of 99.29% is extracted at the 28th plate of the main distillation tower. The carbon dioxide gas flow is discharged at the top of the distillation main tower.

[0058] The main distillation tower of the vacuum distillation bulkhead tower has 55 theoretical plates, the top operating pressure is 0.1kPa, the top operating temperature is 71.1℃, and the bottom operating temperature is 162.3℃; the pre-fractionation tower has 42 theoretical plates, the top operating pressure is 0.1kPa, the top operating temperature is 86.2℃, and the bottom operating temperature is 141.1℃; the bottom discharge of the reactive distillation bulkhead tower is sent to the 21st plate of the pre-fractionation tower. The liquid phase is extracted from the 7th plate of the main distillation tower to the top of the pre-stripping tower, and the top steam of the pre-stripping tower returns to the 8th plate of the main distillation tower. The steam at the bottom of the main distillation tower enters the bottom of the pre-stripping tower from the 51st position, and the liquid phase at the bottom of the pre-stripping tower returns to the 51st plate at the bottom of the main distillation tower. The isosorbide product with a mass fraction of 99.31% is extracted at the 31st plate of the main distillation tower.

[0059] Example 2

[0060] according to Figure 1The process flow shown in the figure is as follows: the main distillation tower of the reactive distillation dividing wall tower has 54 theoretical plates, the top operating pressure is 100 kPa, the top operating temperature is 63.7°C, and the bottom operating temperature is 160.3°C; the reaction sub-tower has 42 theoretical plates, the top operating pressure is 100 kPa, the top operating temperature is 69.3°C, and the bottom operating temperature is 143.1°C; the azeotropic raw material of dimethyl carbonate and methanol (from the alcoholysis process of ethylene carbonate, the content of dimethyl carbonate is 30%) is fed at the 32nd theoretical plate of the reaction sub-tower, and the sorbitol raw material is fed at the 11th theoretical plate of the reaction sub-tower; the molar ratio of dimethyl carbonate and methanol azeotrope to sorbitol is 15; the liquid phase is extracted from the 7th plate of the main distillation tower to the top of the reaction sub-tower, the steam at the top of the reaction sub-tower returns to the 8th plate of the main distillation tower, the steam at the bottom of the main distillation tower enters the bottom of the reaction sub-tower from the 46th plate, and the liquid phase at the bottom of the reaction sub-tower returns to the 46th plate of the lower part of the main distillation tower. The methanol product with a mass fraction of 99.33% is extracted at the 27th plate of the main distillation tower. The carbon dioxide gas stream is discharged at the top of the distillation main tower.

[0061] The main distillation tower of the vacuum distillation bulkhead tower has 60 theoretical plates, the top operating pressure is 0.2kPa, the top operating temperature is 75.1℃, and the bottom operating temperature is 181.5℃; the pre-fractionation tower has 45 theoretical plates, the top operating pressure is 0.2kPa, the top operating temperature is 82.6℃, and the bottom operating temperature is 151.5℃; the bottom discharge of the reactive distillation bulkhead tower is sent to the 23rd plate of the pre-fractionation tower. The liquid phase is extracted from the 8th plate of the main distillation tower to the top of the pre-stripping tower, and the top steam of the pre-stripping tower returns to the 9th theoretical plate of the main distillation tower. The steam at the bottom of the main distillation tower enters the bottom of the pre-stripping tower from the 53rd position, and the liquid phase at the bottom of the pre-stripping tower returns to the 53rd plate at the bottom of the main distillation tower. The isosorbide product with a mass fraction of 99.19% is extracted at the 31st plate of the main distillation tower.

[0062] Example 3

[0063] according to Figure 1The process flow shown in the figure is as follows: the main distillation tower of the reactive distillation dividing wall tower has 64 theoretical plates, the tower top operating pressure is 100 kPa, the tower top operating temperature is 63.6 ° C, and the tower bottom operating temperature is 162.1 ° C; the reactive auxiliary tower has 48 theoretical plates, the tower top operating pressure is 100 kPa, the tower top operating temperature is 68.7 ° C, and the tower bottom operating temperature is 145.3 ° C; the dimethyl carbonate and methanol azeotrope raw material (from the diphenyl carbonate process, the content of dimethyl carbonate is 30 %) is fed at the 36th theoretical plate of the reaction tower, and the sorbitol raw material is fed at the 14th theoretical plate of the reaction tower; the molar ratio of dimethyl carbonate and methanol azeotrope to sorbitol is 20; the liquid phase is extracted from the 10th plate of the main distillation tower to the top of the reaction tower, the steam at the top of the reaction tower returns to the 11th theoretical plate of the main distillation tower, the steam at the bottom of the main distillation tower enters the bottom of the reaction tower from the 55th plate, and the liquid phase at the bottom of the reaction tower returns to the 55th plate of the lower part of the main distillation tower. The methanol product with a mass fraction of 99.59% is extracted at the 32nd plate of the main distillation tower. The carbon dioxide gas stream is discharged at the top of the main distillation tower.

[0064] The main distillation tower of the vacuum distillation bulkhead tower has 70 theoretical plates, the top operating pressure is 0.15kPa, the top operating temperature is 73.1℃, and the bottom operating temperature is 172.8℃; the pre-fractionation tower has 58 theoretical plates, the top operating pressure is 0.15kPa, the top operating temperature is 81.9℃, and the bottom operating temperature is 153.8℃; the bottom discharge of the reactive distillation bulkhead tower is sent to the 29th plate of the pre-fractionation tower. The liquid phase is extracted from the 10th plate of the main distillation tower to the top of the pre-stripping tower, and the top steam of the pre-stripping tower returns to the 11th theoretical plate of the main distillation tower. The steam at the bottom of the main distillation tower enters the bottom of the pre-stripping tower from the 64th position, and the liquid phase at the bottom of the pre-stripping tower returns to the 64th plate at the bottom of the main distillation tower. The isosorbide product with a mass fraction of 99.37% is extracted at the 31st plate of the main distillation tower.

[0065] Example 4

[0066] according to Figure 1The process flow shown in the figure is that the main distillation tower of the reactive distillation dividing wall tower has 70 theoretical plates, the top operating pressure is 100 kPa, the top operating temperature is 63.5 ° C, and the bottom operating temperature is 161.7 ° C; the reaction sub-tower has 52 theoretical plates, the top operating pressure is 100 kPa, the top operating temperature is 68.9 ° C, and the bottom operating temperature is 139.9 ° C; the dimethyl carbonate and methanol azeotrope raw materials are in the 41 theoretical plates of the reaction sub-tower The main distillation tower is fed at the 14th theoretical plate of the reaction tower, and the sorbitol raw material is fed at the 14th theoretical plate of the reaction tower; the molar ratio of dimethyl carbonate and methanol azeotrope to sorbitol is 18; the liquid phase is extracted from the 10th plate of the main distillation tower to the top of the reaction tower, and the steam from the top of the reaction tower returns to the 11th theoretical plate of the main distillation tower. The steam at the bottom of the main distillation tower enters the bottom of the reaction tower from the 64th plate, and the liquid phase at the bottom of the reaction tower returns to the 64th plate of the lower part of the main distillation tower. The methanol product with a mass fraction of 99.62% is extracted at the 36th plate of the main distillation tower. The carbon dioxide gas flow is discharged at the top of the main distillation tower.

[0067] The main distillation tower of the vacuum distillation bulkhead tower has 66 theoretical plates, the top operating pressure is 0.25kPa, the top operating temperature is 81.2℃, and the bottom operating temperature is 191.1℃; the pre-fractionation tower has 54 theoretical plates, the top operating pressure is 0.25kPa, the top operating temperature is 89.7℃, and the bottom operating temperature is 175.6℃; the bottom discharge of the reactive distillation bulkhead tower is sent to the 28th plate of the pre-fractionation tower. The liquid phase is extracted from the 9th plate of the main distillation tower to the top of the pre-stripping tower, and the top steam of the pre-stripping tower returns to the 10th theoretical plate of the main distillation tower. The steam at the bottom of the main distillation tower enters the bottom of the pre-stripping tower from the 58th position, and the liquid phase at the bottom of the pre-stripping tower returns to the 58th plate at the bottom of the main distillation tower. The isosorbide product with a mass fraction of 99.44% is extracted at the 32nd plate of the main distillation tower.

[0068] Example 5

[0069] according to Figure 1As shown in the process flow, the main distillation tower of the reactive distillation dividing wall tower has 60 theoretical plates, the top operating pressure is 80 kPa, the top operating temperature is 57.9°C, and the bottom operating temperature is 148.1°C; the reaction sub-tower has 45 theoretical plates, the top operating pressure is 80 kPa, the top operating temperature is 61.8°C, and the bottom operating temperature is 137.5°C; the dimethyl carbonate and methanol azeotrope raw materials are fed at 30 theoretical plates of the reaction sub-tower, and the sorbitol raw materials are fed at 12 theoretical plates of the reaction sub-tower; the molar ratio of dimethyl carbonate and methanol azeotrope to sorbitol is 26; the liquid phase is extracted from the 8th plate of the main distillation tower to the top of the reaction sub-tower, the steam from the top of the reaction sub-tower returns to the 9th theoretical plate of the main distillation tower, the steam from the lower part of the main distillation tower enters the bottom of the reaction sub-tower from the 50th plate, and the liquid phase at the bottom of the reaction sub-tower returns to the 50th plate of the lower part of the main distillation tower. The methanol product with a mass fraction of 99.29% is produced at the 28th plate of the main distillation tower. The carbon dioxide gas stream is discharged at the top of the main distillation tower.

[0070] The main distillation tower of the vacuum distillation bulkhead tower has 76 theoretical plates, the top operating pressure is 1kPa, the top operating temperature is 129.1℃, and the bottom operating temperature is 276.5℃; the pre-fractionation tower has 58 theoretical plates, the top operating pressure is 1kPa, the top operating temperature is 151.2℃, and the bottom operating temperature is 248.1℃; the bottom discharge of the reactive distillation bulkhead tower is sent to the 31st plate of the pre-fractionation tower. The liquid phase is extracted from the 10th plate of the main distillation tower to the top of the pre-stripping tower, and the top steam of the pre-stripping tower returns to the 11th theoretical plate of the main distillation tower. The steam at the bottom of the main distillation tower enters the bottom of the pre-stripping tower from the 71st position, and the liquid phase at the bottom of the pre-stripping tower returns to the 71st plate at the bottom of the main distillation tower. The isosorbide product with a mass fraction of 99.57% is extracted at the 38th plate of the main distillation tower.

[0071] Example 6

[0072] according to Figure 1As shown in the process flow, the main distillation tower of the reactive distillation dividing wall tower has 76 theoretical plates, the top operating pressure is 50 kPa, the top operating temperature is 46.3°C, and the bottom operating temperature is 120°C; the reaction sub-tower has 58 theoretical plates, the top operating pressure is 50 kPa, the top operating temperature is 52.7°C, and the bottom operating temperature is 101.9°C; the dimethyl carbonate and methanol azeotrope raw materials are fed at 45 theoretical plates of the reaction sub-tower, and the sorbitol raw materials are fed at 15 theoretical plates of the reaction sub-tower; the molar ratio of dimethyl carbonate and methanol azeotrope to sorbitol is 30; the liquid phase is extracted from the 12th plate of the main distillation tower to the top of the reaction sub-tower, the steam from the top of the reaction sub-tower returns to the 13th theoretical plate of the main distillation tower, the steam from the lower part of the main distillation tower enters the bottom of the reaction sub-tower from the 72nd plate, and the liquid phase at the bottom of the reaction sub-tower returns to the 72nd plate of the lower part of the main distillation tower. The methanol product with a mass fraction of 99.71% is produced at the 39th plate of the main distillation tower. The carbon dioxide gas stream is discharged at the top of the main distillation tower.

[0073] The main distillation tower of the vacuum distillation bulkhead tower has 66 theoretical plates, the top operating pressure is 2kPa, the top operating temperature is 132.1℃, and the bottom operating temperature is 282.1℃; the pre-fractionation tower has 54 theoretical plates, the top operating pressure is 2kPa, the top operating temperature is 152.9℃, and the bottom operating temperature is 253.5℃; the bottom discharge of the reactive distillation bulkhead tower is sent to the 29th plate of the pre-fractionation tower. The liquid phase is extracted from the 9th plate of the main distillation tower to the top of the pre-stripping tower, and the top steam of the pre-stripping tower returns to the 10th theoretical plate of the main distillation tower. The steam at the bottom of the main distillation tower enters the bottom of the pre-stripping tower from the 59th position, and the liquid phase at the bottom of the pre-stripping tower returns to the 59th plate at the bottom of the main distillation tower. The isosorbide product with a mass fraction of 99.27% ​​is extracted at the 34th plate of the main distillation tower.

[0074] Example 7

[0075] according to Figure 1 The process flow shown in the figure has the same operating conditions as in Example 1, and the sorbitol feed amount is the same as in Example 1, and pure dimethyl carbonate is used as feed. The feed amount of pure dimethyl carbonate is consistent with the amount of dimethyl carbonate in the azeotrope in Example 1. The mass fraction of isosorbide product extracted at the 31st plate of the vacuum main distillation tower is 98.84%, which is lower than that of Example 1. The material cost of pure dimethyl carbonate is much higher than that of dimethyl carbonate and methanol azeotrope, and the byproduct methanol in Example 7 is also greatly reduced relative to that in Example 1.

[0076] Comparative Example 1

[0077] according to Figure 2The common reaction distillation tower and the common vacuum distillation tower are used in the combined process, and the feed amount of sorbitol and azeotrope is the same as that in Example 1. The common reaction distillation tower has 60 theoretical plates, the tower top operating pressure is 100KPa, and the tower top operating temperature is 63.7°C; the common vacuum distillation tower has 55 theoretical plates, the tower top operating pressure is 0.1KPa, and the tower top operating temperature is 71.1°C. It is impossible to obtain high-purity isosorbide by using the common reaction distillation tower and the common vacuum distillation tower combined process, and only a mixture of isosorbide and intermediate products can be obtained. To obtain isosorbide, an additional vacuum distillation device needs to be added. It is impossible to obtain high-purity methanol byproduct by using the common reaction distillation tower and the common vacuum distillation tower combined process, and only a mixture of dimethyl carbonate and methanol (non-azeotrope) can be obtained.

[0078] Comparative Example 2

[0079] The vacuum distillation tower in Example 1 was changed into an atmospheric distillation tower, and the operating conditions of the reaction distillation tower were the same as those in Example 1. The main distillation tower of the atmospheric distillation distillation tower has 55 theoretical plates, the top operating pressure is 100kPa, the top operating temperature is 300℃, and the bottom operating temperature is 429℃; the pre-fractionation tower has 42 theoretical plates, the top operating pressure is 100kPa, the top operating temperature is 318℃, and the bottom operating temperature is 409℃; the bottom discharge of the reaction distillation distillation tower is sent to the 21 plates of the pre-fractionation tower. The liquid phase is extracted from the 7 plates of the main distillation tower to the top of the pre-stripping tower, and the steam from the top of the pre-stripping tower returns to the 8th plate of the main distillation tower. The steam at the bottom of the main distillation tower enters the bottom of the pre-stripping tower from the 51st position, and the liquid phase at the bottom of the pre-stripping tower returns to the 51st plate at the bottom of the main distillation tower. The isosorbide product with a mass fraction of 95.97% was extracted at the 31st plate of the main distillation tower. The energy consumption of the atmospheric pressure dividing wall distillation tower increased by 187% compared with the energy consumption of the vacuum dividing wall distillation tower in Example 1.

[0080] It can be seen from the results of the examples and comparative examples that the embodiments of the present invention can improve the purity of isosorbide, reduce process energy consumption, reduce raw material costs and reduce equipment investment.

[0081] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for producing isosorbide and co-producing methanol, characterized in that: The method includes: a. contacting a dimethyl carbonate raw material with a sorbitol raw material for reaction and distillation to obtain methanol, dimethyl carbonate and methanol azeotrope and other product streams; b. The other product streams are subjected to vacuum distillation to obtain isosorbide, unreacted sorbitol and a heavy component intermediate product stream.

2. The method according to claim 1, wherein: The dimethyl carbonate raw material is selected from dimethyl carbonate or a mixture of dimethyl carbonate and methanol, preferably a mixture of dimethyl carbonate and methanol; It is further preferred that the molar content of dimethyl carbonate in the mixture of dimethyl carbonate and methanol is 0.14-0.25; More preferably, the mixture of dimethyl carbonate and methanol comes from at least one of the processes of preparing ethylene glycol and dimethyl carbonate by reacting ethylene carbonate with methanol, preparing diphenyl carbonate by reacting phenol with dimethyl carbonate, and preparing methyl phenylcarbamate by reacting aniline with dimethyl carbonate.

3. The method according to claim 1 or 2, wherein: The reactive distillation comprises a crude reactive distillation stage and a first distillation stage along the flow direction; and / or The vacuum distillation comprises a pre-fractionation stage and a second distillation stage along the flow direction.

4. The method according to any one of claims 1 to 3, wherein: In step a, the dimethyl carbonate and methanol azeotrope is recycled back to the dimethyl carbonate raw material; and / or In step b, the unreacted sorbitol is recycled back into the sorbitol raw material.

5. The method according to any one of claims 1 to 4, wherein: The reactive distillation is carried out in a reactive distillation dividing wall tower comprising a reaction sub-tower and a distillation main tower, and comprises: The dimethyl carbonate raw material and the sorbitol raw material are contacted and reacted in the reaction sub-tower, and the obtained first gas phase product and the first liquid phase product are passed into the main distillation tower for distillation separation to obtain methanol, dimethyl carbonate and methanol azeotrope and other product streams; preferably, the dimethyl carbonate raw material is fed at the 15th to 55th theoretical plates of the reaction sub-tower, the sorbitol raw material is fed at the 5th to 20th theoretical plates of the reaction sub-tower, the first gas phase product is fed at the 6th to 16th theoretical plates of the main distillation tower, the first liquid phase product is fed at the 26th to 86th theoretical plates of the main distillation tower, methanol is discharged at the 15th to 55th theoretical plates of the main distillation tower, dimethyl carbonate and methanol azeotrope is discharged at the top of the main distillation tower, and other product streams are discharged at the bottom of the main distillation tower; and / or The main distillation tower also separates a gaseous mixture and / or liquid mixture of methanol and dimethyl carbonate, and circulates them back to the reaction sub-tower. Preferably, the liquid mixture is discharged from the 5th to 15th theoretical plates of the main distillation tower and circulated back to the top of the reaction sub-tower, and the gaseous mixture is discharged from the 26th to 86th theoretical plates of the main distillation tower and circulated back to the bottom of the reaction sub-tower.

6. The method according to any one of claims 1 to 5, wherein: The vacuum distillation is carried out in a vacuum distillation dividing wall tower comprising a pre-fractionation side tower and a distillation main tower, comprising: The other product streams are obtained by rough separation in the pre-fractionation side tower, and the obtained second gas phase product and second liquid phase product are introduced into the main distillation tower for distillation separation to obtain isosorbide, unreacted sorbitol and a heavy component intermediate product stream; preferably, the other product streams are fed to the 10th to 40th theoretical plates of the pre-fractionation side tower, the second gas phase product is fed to the 6th to 16th theoretical plates of the main distillation tower, the first liquid phase product is fed to the 26th to 86th theoretical plates of the main distillation tower, isosorbide is discharged from the 15th to 60th theoretical plates of the main distillation tower, unreacted sorbitol is discharged from the top of the main distillation tower, and the heavy component intermediate product stream is discharged from the bottom of the main distillation tower; and / or The main distillation tower also separates a gaseous mixture and / or liquid mixture of sorbitol and isosorbide, and circulates them back to the pre-fractionation sub-tower. Preferably, the liquid mixture is discharged from the 5th to 15th theoretical plates of the main distillation tower and circulated back to the top of the reaction sub-tower, and the gaseous mixture is discharged from the 26th to 86th theoretical plates of the main distillation tower and circulated back to the bottom of the reaction sub-tower.

7. The method according to claim 5, wherein: The main distillation tower in the reactive distillation dividing wall tower has a theoretical plate number of 30-100, a tower top operating pressure of 10-100 kPa, a tower top operating temperature of 13.2-64° C., and a tower bottom operating temperature of 60-160° C.; and / or The number of theoretical plates of the reaction sub-tower in the reaction distillation dividing wall tower is 20-70, the operating pressure at the top of the tower is 10-100 kPa, the operating temperature at the top of the tower is 18-70°C, and the operating temperature at the bottom of the tower is 50-140°C.

8. The method according to claim 6, wherein: The main distillation tower in the vacuum distillation dividing wall tower has a theoretical plate number of 30-100, a tower top operating pressure of 0.1-30 kPa, a tower top operating temperature of 70-200° C., and a tower bottom operating temperature of 160-350° C.; and / or The number of theoretical plates of the pre-fractionation sub-tower in the vacuum distillation dividing wall tower is 20-70, the operating pressure at the top of the tower is 0.1-30 kPa, the operating temperature at the top of the tower is 85-220° C., and the operating temperature at the bottom of the tower is 140-320° C.

9. The method according to any one of claims 1 to 8, wherein: The contacting is carried out in the presence of a catalyst, and preferably the catalyst is selected from a homogeneous acid-base catalyst and / or a heterogeneous acid-base catalyst.

10. The method according to any one of claims 1 to 9, wherein: The contacting conditions include: the molar ratio of the dimethyl carbonate raw material calculated as dimethyl carbonate to the sorbitol raw material calculated as sorbitol is 1-50, preferably 10-30; and / or The conditions of the reactive distillation include: the tower top temperature is 13.2-70°C, preferably 46.3-64°C; The pressure is 10-100 kPa, preferably 50-100 kPa; and / or The conditions of the vacuum distillation include: the tower top temperature is 70-220°C, preferably 70-160°C; the pressure is 0.1-30kPa, 0.1-10kPa.

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