Process and reactor for the hydrogenation of oxalate esters to ethanol

Abstract

The application discloses a kind of oxalate hydrogenation preparation ethanol catalytic method and device, belong to chemical industry technical field.The device includes reaction rectifying tower, condensing unit and heating unit I;Reaction rectifying tower includes rectifying unit, reaction unit and stripping unit in turn;Rectifying unit is equipped with outlet I and reflux inlet I;Reaction unit is equipped with feed inlet I and feed inlet II;Stripping unit is equipped with outlet II;Reaction unit fills catalyst;Rectifying unit is equipped with multiple layers of tray;Rectifying unit and condensing unit are communicated, and condensing unit is used to condense the separated gas phase material into liquid phase ethanol;Stripping unit and heating unit are communicated, and stripping unit is used to continue and hydrogen reaction after gasification of liquid phase material using the heat supply of heating unit I.The catalytic reaction rectifying device designed in the application makes oxalate conversion rate 100%, ethanol selectivity is more than 99%, and the product after reaction can realize preliminary separation, and greatly reduces subsequent purification energy consumption and production cost.

Description

Technical Field

[0001] This application belongs to the field of chemical technology, and in particular relates to a method and reaction apparatus for the hydrogenation of oxalate ester to ethanol. Background Technology

[0002] Ethanol, commonly known as alcohol, is an important chemical raw material widely used in food, chemical, military, and pharmaceutical industries. Due to its high oxygen content (34.7%), ethanol can serve as an excellent gasoline additive, increasing the oxygen content of the fuel, resulting in more complete combustion and reducing emissions of pollutants such as CO. As a green and clean automotive fuel, ethanol production has become a key focus of clean energy development worldwide. For my country, fuel ethanol aligns with the development direction of energy substitution and renewable energy, offering significant economic and social benefits.

[0003] There are three main routes for producing ethanol. One is the petroleum route, which uses ethylene, a product of petroleum cracking, as a raw material and hydrates it to obtain ethanol. Another is the bio-fermentation route, which uses various sugary agricultural products, agricultural and forestry byproducts, and wild plants as raw materials, hydrolyzing and fermenting them to convert disaccharides and polysaccharides into monosaccharides, which are then further converted into ethanol. The third is the coal route, which mainly includes the following four methods: First, direct ethanol production from syngas; this method produces complex products and has high separation costs, and is currently under development. Second, ethanol is produced from coal-to-acetic acid and then hydrogenated; this method uses a large amount of strong acid, resulting in high equipment investment costs. Third, ethanol is produced from coal-to-acetic acid esters and then hydrogenated; this method has been industrialized, but the coal-to-acetic acid ester process is currently inefficient and has high equipment investment costs. Fourth, ethanol is produced from coal-to-oxalate esters and then hydrogenated. Due to the rapid development of coal-to-ethylene glycol technology in China, the technology for preparing dimethyl oxalate from coal via syngas is relatively mature, and the cost of hydrogenating ester to ethanol is low. Therefore, the research on hydrogenating dimethyl oxalate to ethanol can not only provide a new conversion route for domestic coal chemical industry, but also alleviate the domestic demand for ethanol to a certain extent, which has important practical significance.

[0004] Existing technology discloses a two-stage process for the hydrogenation of oxalate to ethanol. This process splits the original single-stage high-temperature reactor into two stages. The conversion of oxalate is achieved in a low-temperature reactor, while further hydrogenation of the product is carried out in a high-temperature reactor. This suppresses the formation of glycerols and tetraols, thus achieving high selectivity for ethanol. In the two-stage process for the hydrogenation of oxalate to ethanol, with a first-stage reaction temperature of 200℃, a second-stage reaction temperature of 280℃, a reaction pressure of 2.5 MPa, a first-stage molar hydrogen-to-ester ratio of 80, a second-stage molar hydrogen-to-ester ratio of 200, and an oxalate mass hourly space velocity of 1.0 h⁻¹, the oxalate conversion rate is 100%, and the ethanol selectivity is as high as 85.0%.

[0005] Existing catalytic reaction devices are all fixed-bed reactors, or use a single reactor for direct hydrogenation of oxalate to ethanol, or employ two reactors in two stages or in series. The first stage (or the first reactor) hydrogenates to produce methyl glycolate and ethylene glycol, while the second stage (or the second reactor) further hydrogenates to produce ethanol. All hydrogenation products (methanol, ethanol, ethylene glycol, methyl glycolate, dimethyl oxalate, and high-boiling polymers) are then separated by downstream distillation. This method involves complex product separation and purification processes, resulting in high costs.

[0006] Furthermore, existing methods for hydrogenating oxalate esters to ethanol generally suffer from problems such as high reaction temperatures, easy catalyst aggregation, low oxalate ester conversion rates, and low ethanol selectivity, which hinder the industrial development of the technology. Summary of the Invention

[0007] In view of this, this application provides a method and reaction apparatus for the hydrogenation of oxalate to ethanol, the main purpose of which is to solve the technical problems of cumbersome separation and purification process of oxalate hydrogenation to ethanol product and the need to improve oxalate conversion rate and ethanol selectivity.

[0008] On the one hand, this application provides a catalytic reaction apparatus for the hydrogenation of oxalate to ethanol, the reaction apparatus comprising a reactive distillation column, a condensation unit and a heating unit I;

[0009] The reactive distillation column comprises, from top to bottom, a connected distillation unit, a reaction unit, and a stripping unit.

[0010] The distillation unit is equipped with a top outlet I and a reflux inlet I;

[0011] The reaction unit is equipped with raw material inlet I and raw material inlet II;

[0012] The distillation unit is equipped with a bottom outlet II;

[0013] The reaction unit is filled with a catalyst to catalyze the reaction of oxalate and hydrogen to produce a mixed product.

[0014] The distillation unit is equipped with multiple trays for separating products with different boiling points from the mixed products;

[0015] The distillation unit and the condensation unit are connected, and the condensation unit is used to condense the gaseous material separated by the distillation unit into a liquid material.

[0016] The distillation unit is connected to the heating unit I. The distillation unit is used to vaporize the liquid material in the distillation unit by using the heat supplied by the heating unit I, and then continue to react with hydrogen.

[0017] The catalytic reaction apparatus of this application not only has a high oxalate conversion rate (100%) and a high ethanol selectivity (over 99%), but also enables preliminary separation of the reaction products, significantly reducing the energy consumption for subsequent purification. Therefore, the use of the catalytic reaction distillation apparatus of this application helps to significantly reduce the production cost of ethanol from oxalate.

[0018] Optionally, the distillation unit is an atmospheric distillation column with a theoretical plate number of 20 to 50.

[0019] Optionally, the reaction unit is an isothermal plate reactor; the catalyst is spread flat on the reactor plates.

[0020] Optionally, the distillation unit is an insulated vessel.

[0021] Optionally, the condensation unit includes a condenser and a reflux tank. The inlet of the condenser is connected to the top outlet I, the outlet of the condenser is connected to the inlet of the reflux tank, the outlet I of the reflux tank is connected to the reflux inlet I of the distillation unit, and the outlet II of the reflux tank is the product outlet.

[0022] Optionally, the heating unit I is a bottom reboiler I; the inlet of the reboiler I is connected to the bottom outlet II of the stripping unit, and the outlet of the reboiler I is connected to the feed inlet II of the reaction unit.

[0023] Optionally, the feed inlet I of the reaction unit is located at its bottom for feeding a mixture of oxalate and hydrogen; the feed inlet II is located at the bottom of the reaction unit for returning the material from the distillation unit to the reaction unit after reboiling and vaporization.

[0024] Optionally, the top of the reaction unit is also provided with a discharge port III for discharging the mixed product after the reaction; the distillation unit is also provided with a reflux inlet II.

[0025] Optionally, the device further includes a heat exchange unit and a heating unit II;

[0026] The discharge port III of the reaction unit is connected to the inlet of the heat exchange unit, and the heat exchange unit is used to separate the gas and liquid phases of the mixed products generated by the reaction unit.

[0027] The liquid phase outlet of the heat exchange unit is connected to the reflux inlet II of the distillation unit, the gas phase outlet of the heat exchange unit is connected to the inlet I of the heating unit II, and the outlet of the heating unit II is connected to the reflux inlet I of the rectification unit. The heating unit II is used to supply heat to the rectification unit.

[0028] Optionally, the outlet I of the reflux tank and the inlet II of the heating unit II are connected.

[0029] Optionally, the heat exchange unit is a cold and hot flow heat exchanger, where the cold flow is condensate and the hot flow is a mixture of products generated by the reaction unit.

[0030] The heating unit I or the heating unit II uses steam for heating.

[0031] Optionally, the bottom of the distillation unit and the top of the reaction unit are connected by pipe I; the bottom of the reaction unit and the top of the stripping unit are connected by pipe II.

[0032] Optionally, valve I is installed on pipe I; valve II is installed on pipe II.

[0033] The physical connection methods between the distillation unit, reaction unit, and stripping unit in this application are existing technologies, and those skilled in the art can select them according to actual needs.

[0034] Secondly, this application provides a method for the hydrogenation of oxalate ester to ethanol, wherein the method is carried out in the above-mentioned reaction apparatus.

[0035] Optionally, the method includes the following steps:

[0036] S1: Material I, containing oxalate and hydrogen, reacts with the catalyst in the reaction unit to generate material II;

[0037] S2: Material II is separated by a distillation unit to obtain material III with a boiling point of 45-100℃ and material IV with a boiling point of 110-250℃.

[0038] Material III is separated into a gas phase and a liquid phase containing ethanol after passing through a condensation unit;

[0039] After material IV enters the distillation unit, it is reboiled and vaporized before reacting with hydrogen to produce ethanol.

[0040] Optionally, material III contains hydrogen, ethanol, and methanol;

[0041] Material IV contains methyl glycolate, ethylene glycol, and a portion of oxalate.

[0042] Optionally, the hydrogen separated from material III is mixed and reacted with material I; and / or, the hydrogen separated from material III is mixed and reacted with the vaporized material IV.

[0043] Optionally, in step S1, the hydrogen gas to oxalate ester molar ratio is 20 to 200:1.

[0044] Optionally, the liquid hourly space velocity of the oxalate is 0.1 to 1.5 h⁻¹. -1 .

[0045] Optionally, the reaction temperature of the oxalate ester and hydrogen in the reaction unit is 170-250°C, and the reaction pressure is 0.5-3.5 MPa.

[0046] Optionally, in step S1, the hydrogen gas to oxalate ester molar ratio is 60-80:1.

[0047] Optionally, the liquid hourly space velocity of the oxalate is 0.3–0.8 h⁻¹. -1 .

[0048] Optionally, the reaction temperature of the oxalate ester with hydrogen is 180–220°C, and the reaction pressure is 2.0–3.0 MPa.

[0049] Optionally, the hydrogen ester molar ratio is selected from any value or a range between any two of 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, and 200.

[0050] Optionally, the liquid hourly space velocity of the oxalate is selected from 0.1, 0.3, 0.5, 0.8, 1.0, 1.2, and 1.5 h⁻¹. -1 Any value in the range or any value between the two.

[0051] Optionally, the reaction temperature of the oxalate ester with hydrogen is selected from any value of 170, 180, 190, 200, 210, 220, 230, 240, 250 °C or a range between any two; the reaction pressure is selected from any value of 0.5, 0.8, 1.0, 1.2, 1.5, 1.8, 2.0, 2.2, 2.5, 2.8, 3.0, 3.2, 3.5 MPa or a range between any two.

[0052] Optionally, in step S2, the bottom temperature of the distillation unit is 100-150°C, the top temperature of the distillation unit is 65-110°C, the pressure inside the distillation unit is 0.05-0.20 MPa, and the condensation temperature of the condensation unit is 10-60°C.

[0053] Optionally, in step S2, the bottom temperature of the distillation unit is 110–140°C, the top temperature of the distillation unit is 90–105°C, and the condensation temperature of the condensation unit is 30–60°C.

[0054] Optionally, the bottom temperature of the distillation unit is selected from any value of 100, 110, 120, 130, 140, 150°C or a range between any two; the top temperature of the distillation unit is selected from any value of 65, 70, 75, 80, 85, 90, 95, 100, 105, 110°C or a range between any two.

[0055] Optionally, in step S2, the temperature of the distillation unit's bottom column is 170–210°C; and the temperature of the heating unit I after heating is 180–210°C.

[0056] Optionally, in step S2, the temperature of the distillation unit's bottom column is 170–210°C; and the temperature of the heating unit I after heating is 190–200°C.

[0057] Optionally, the temperature after heating by the heating unit I is selected from any value of 180, 185, 190, 195, 200, 205, 210℃ or any range between two.

[0058] Optionally, the catalyst is selected from Cu-Ni / SiO2 catalysts; in the Cu-Ni / SiO2 catalyst, metallic Cu accounts for 5-10% of the total mass of the catalyst, metallic Ni accounts for 8-12% of the total mass of the catalyst, and the support is SiO2.

[0059] Compared with the prior art, this application has the following beneficial effects:

[0060] This application employs a novel catalytic reactive distillation apparatus for the hydrogenation of oxalate to ethanol. This apparatus not only boasts a high oxalate conversion rate (100%) and high ethanol selectivity (over 99%), but also enables preliminary separation of the reaction products, significantly reducing the energy consumption for subsequent purification. Therefore, the use of this catalytic reactive distillation apparatus helps to substantially reduce the production cost of ethanol from oxalate. Attached Figure Description

[0061] Figure 1 This is a schematic diagram of the catalytic reaction apparatus for the hydrogenation of oxalate to ethanol in Example 1 of this application.

[0062] Figure 2 This is a schematic diagram of the catalytic reaction apparatus for the hydrogenation of oxalate to ethanol in Examples 2-7 of this application.

[0063] Figure Labels

[0064] X is the stripping section, Y is the reaction section, and Z is the rectification section;

[0065] 1-Reaction section feed inlet I, 2-Catalyst-filled tray, 3-Reaction section outlet III, 4-Heat exchanger (1 inlet, 1 vapor phase outlet, 1 liquid phase outlet, not labeled), 5-Rectifying section reboiler II (2 inlets, 1 outlet, not labeled), 6-Rectifying section reflux inlet I, 7-Rectifying section top outlet I, 8-Rectifying section condenser, 9-Condenser non-condensable gas outlet, 10-Rectifying section reflux tank, 11-Rectifying section reflux tank product outlet II (another one is outlet I, not labeled), 12-Stripping section bottom outlet II, 13-Stripping section discharge outlet, 14-Stripping section reboiler I (1 inlet, 1 outlet, not labeled), 15-Reaction section feed inlet II, 16-Stripping section reflux inlet II. Detailed Implementation

[0066] The present application is further illustrated below with reference to specific embodiments. The following descriptions are merely a few embodiments of the present application and are not intended to limit the present application in any way. Although the present application discloses preferred embodiments as follows, they are not intended to limit the present application. Any modifications or variations made by those skilled in the art without departing from the scope of the technical solution of the present application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

[0067] Unless otherwise specified, the raw materials used in the embodiments of this application are all purchased commercially and used directly without any special treatment.

[0068] Example 1

[0069] Catalytic reaction apparatus for the hydrogenation of oxalate esters to ethanol, such as... Figure 1 As shown: It includes a reactive distillation column, a condensation unit and a heating unit I; the reactive distillation column includes a distillation unit X, a reaction unit Y and a stripping unit Z connected from top to bottom; the distillation unit is equipped with a top outlet I (7) and a reflux inlet I (6); the reaction unit is equipped with a raw material inlet I (1) and a feed inlet II (15); the stripping unit is equipped with a bottom outlet II (12); the reaction unit is filled with a catalyst to catalyze the reaction of oxalate and hydrogen to generate a mixed product; the distillation unit is equipped with multi-layer trays to separate products with different boiling points in the mixed product; the distillation unit and the condensation unit (8) are connected, and the condensation unit is used to condense the gaseous material separated by the distillation unit into a liquid material; the stripping unit and the heating unit (14) are connected, and the stripping unit is used to use the heat supplied by the heating unit I to vaporize the liquid material in the stripping unit and continue to react with hydrogen; the process conditions and reaction results are shown in Table 1.

[0070] As a preferred embodiment of the above, the distillation unit is an atmospheric distillation column with a theoretical plate number of 20 to 50.

[0071] As a preferred embodiment of the above, the reaction unit is an isothermal plate reactor; the catalyst is spread evenly on the reactor plates.

[0072] As a preferred embodiment of the above, the distillation unit is an insulated vessel.

[0073] As a preferred embodiment of the above, the condensation unit includes a condenser and a reflux tank (10). The inlet and top outlet I of the condenser are connected, the outlet of the condenser is connected to the inlet of the reflux tank, the outlet I of the reflux tank is connected to the reflux inlet I of the distillation unit, and the outlet II of the reflux tank is the product outlet.

[0074] As a preferred embodiment of the above, the heating unit I is a bottom reboiler I (14); the inlet of the reboiler I is connected to the bottom outlet II of the stripping unit, and the outlet of the reboiler I is connected to the feed inlet II of the reaction unit.

[0075] As a preferred embodiment of the above, the feed inlet I of the reaction unit is located at its bottom for feeding a mixture of oxalate ester and hydrogen; the feed inlet II is located at the bottom of the reaction unit for returning the material from the distillation unit to the reaction unit after reboiling and vaporization.

[0076] As a preferred embodiment of the above, the top of the reaction unit is also provided with a discharge port III (3) for discharging the mixed product after the reaction; the distillation unit is also provided with a reflux inlet II.

[0077] As a preferred embodiment of the above, the device further includes a heat exchange unit (4) and a heating unit II (5);

[0078] The discharge port III of the reaction unit is connected to the inlet of the heat exchange unit, which is used to separate the gas and liquid phases of the mixed products generated by the reaction unit.

[0079] The liquid phase outlet of the heat exchange unit is connected to the reflux inlet II of the distillation unit, the gas phase outlet of the heat exchange unit is connected to the inlet I of the heating unit II, and the outlet of the heating unit II is connected to the reflux inlet I of the distillation unit. The heating unit II is used to supply heat to the distillation unit.

[0080] As a preferred embodiment of the above, the outlet I of the reflux tank and the inlet II of the heating unit II are connected.

[0081] As a preferred embodiment of the above, the heat exchange unit is a cold and hot flow heat exchanger, where the cold flow is condensate and the hot flow is the mixed product generated by the reaction unit.

[0082] Heating unit I or heating unit II uses steam for heating.

[0083] As a preferred embodiment of the above, the bottom of the distillation unit and the top of the reaction unit are connected by pipe I; the bottom of the reaction unit and the top of the stripping unit are connected by pipe II.

[0084] As a preferred embodiment of the above, valve I is provided on pipe I; valve II is provided on pipe II.

[0085] The physical connection methods between the distillation unit, reaction unit, and stripping unit in this application are existing technologies, and those skilled in the art can select them according to actual needs.

[0086] The catalytic reaction apparatus provided in Example 1 can achieve a 100% oxalate conversion rate and an ethanol selectivity of over 99%. Moreover, the products after the reaction can be initially separated, which greatly reduces the energy consumption for subsequent purification. Therefore, the use of the catalytic reaction distillation apparatus in this application helps to significantly reduce the production cost of ethanol from oxalate.

[0087] This application uses preferred device structures and preferred process parameters as examples to illustrate the technology of this application, such as Examples 2-7.

[0088] Example 2

[0089] Catalyst preparation: 73.26 g Cu(NO3)2·2.5H2O and 49.29 g Ni(NO3)2·6H2O were added to a 3000 mL beaker, followed by 200 mL of 1.5 mol / L dilute nitric acid solution. After stirring until completely dissolved, 352.34 g tetraethyl orthosilicate solution was gradually added dropwise. The mixture was stirred rapidly for 2 h, heated to 80 °C, and ammonia water was gradually added dropwise until the pH reached 9. After stirring rapidly for 3 h, the mixture was stopped and cooled to room temperature. The mixture was allowed to stand for 5 h, and the resulting solution was filtered. The filtered solid was washed three times with deionized water, dried in an oven at 120 °C for 8 h, and then calcined in a muffle furnace at 300 °C for 12 h to obtain a light blue powder with a Cu weight percentage of 10% and a Ni weight percentage of 10%. The catalyst was pressed into tablets and then sieved to a 10-20 mesh size to obtain the desired Cu-Ni / SiO2 catalyst.

[0090] Oxalate to ethanol: Weigh 20g of the catalyst prepared above and load it onto the tray of the reaction section (Y). After N2 replacement, H2 is introduced and the reaction proceeds for 1500 h. -1 The oxalate was reduced for 20 hours at a space velocity of 2.5 MPa and a temperature of 250°C, and then cooled to 190°C in preparation for the reaction. The vaporized oxalate was mixed with H2 and introduced into the reactor from the lower end (1) of the reaction section, with the liquid hourly space velocity of the oxalate controlled at 0.5 h⁻¹. -1The hydrogen-ester molar ratio is controlled at 80:1, and the reactor pressure is controlled at 2.5 MPa. After the reaction, the material enters the heat exchange unit for heat exchange and separation. The low-boiling-point material enters the rectification section (Z) for atmospheric distillation, and the high-boiling-point material enters the stripping tower (X) for further hydrogenation reaction. The bottom temperature of the rectification section is controlled at 140℃, and the top temperature of the rectification section is controlled at 105℃. The low-boiling-point methanol, ethanol, water and non-condensable gas (mainly unreacted H2) enter the condenser (8) from the top outlet (7) of the tower for condensation. The condensation temperature is controlled at 50℃. The low-boiling-point species enter the reflux tank (10) from the bottom outlet of the condenser. The unqualified products in the reflux tank are returned to the rectification tube for circulating distillation through (6). After the product is qualified, it is taken out from the outlet (11) of the reflux tank. H2 is taken out from the condenser (11) and recycled. High-boiling-point oxalate, methyl glycolate, and ethylene glycol are refluxed from heat exchanger (4) to the inlet (16) of the stripping section for reboiling reaction. The temperature of the reboiler in the stripping section is controlled at 198°C. After reboiling, the vaporized oxalate, methyl glycolate, and ethylene glycol enter the reaction section from the inlet (15), mix with H2 at the lower end (1) of the reaction section, and then enter the reaction section (Y) for reaction, so that the oxalate, methyl glycolate, and ethylene glycol are completely converted into ethanol. Samples are taken from (11) and (12) at 2-hour intervals, and the product composition is analyzed by gas chromatography using an FID detector. The conversion rate of oxalate and the selectivity of ethanol are calculated. The structure of the device is as follows. Figure 2 As shown, the reaction results are shown in Table 1.

[0091] Example 3

[0092] Catalyst preparation: 73.26 g Cu(NO3)2·2.5H2O and 24.65 g Ni(NO3)2·6H2O were added to a 3000 mL beaker, followed by 200 mL of 1.5 mol / L dilute nitric acid solution. After stirring until completely dissolved, 352.34 g tetraethyl orthosilicate solution was gradually added dropwise, and the mixture was stirred rapidly for 2 h. The temperature was raised to 80 °C, and ammonia water was gradually added dropwise until the pH reached 9.5. After stirring rapidly for 3 h, stirring was stopped, and the mixture was cooled to room temperature and allowed to stand for 5 h. The resulting solution was filtered, and the filtered solid was washed three times with deionized water. It was then dried in an oven at 120 °C for 8 h, and then calcined in a muffle furnace at 300 °C for 12 h to obtain a light blue powder with a Cu weight percentage of 10% and a Ni weight percentage of 5%. The catalyst was pressed into tablets and then sieved to a 10-20 mesh size to obtain the desired Cu-Ni / SiO2 catalyst.

[0093] Oxalate to ethanol: Weigh 20g of catalyst and load it onto the tray of reaction section (Y). After N2 replacement, H2 is introduced and the reaction proceeds for 1500 h. -1The oxalate was reduced for 20 hours at a space velocity of 1.5 MPa and a temperature of 250°C, and then cooled to 180°C in preparation for the reaction. The vaporized oxalate was mixed with H2 and entered the reactor from the lower end (1) of the reaction section, with the liquid hourly space velocity of the oxalate controlled at 0.3 h⁻¹. -1 The hydrogen-ester molar ratio is controlled at 80:1, and the reactor pressure is controlled at 1.5 MPa. After the reaction, the material enters the heat exchange unit for heat exchange separation. The low-boiling-point material enters the rectification section (Z) for atmospheric distillation, and the high-boiling-point material enters the stripping tower (X) for further hydrogenation reaction. The bottom temperature of the rectification section is controlled at 150℃, and the top temperature of the rectification section is controlled at 102℃. The low-boiling-point methanol, ethanol, water and non-condensable gas (mainly unreacted H2) enter the condenser (8) from the top outlet (7) of the tower for condensation. The condensation temperature is controlled at 40℃. The low-boiling-point species enter the reflux tank (10) from the bottom outlet of the condenser. The unqualified products in the reflux tank are returned to the rectification tube for circulating distillation through (6). After the product is qualified, it is taken out from the outlet (11) of the reflux tank. H2 is taken out from the condenser (11) and recycled. High-boiling-point oxalate, methyl glycolate, and ethylene glycol are refluxed from heat exchanger (4) to the inlet (16) of the stripping section for reboiling reaction. The temperature of the reboiler in the stripping section is controlled at 200°C. After reboiling, the vaporized oxalate, methyl glycolate, and ethylene glycol enter the reaction section from the inlet (15), mix with H2 at the lower end (1) of the reaction section, and then enter the reaction section (Y) for reaction, so that the oxalate, methyl glycolate, and ethylene glycol are completely converted into ethanol. Samples are taken from (11) and (12) at 2-hour intervals, and the composition of the products is analyzed by gas chromatography using an FID detector. The conversion rate of oxalate and the selectivity of ethanol are calculated. The structure of the device is as follows. Figure 2 As shown, the reaction results are shown in Table 1.

[0094] Example 4

[0095] Catalyst preparation: 36.63 g Cu(NO3)2·2.5H2O and 49.29 g Ni(NO3)2·6H2O were added to a 3000 mL beaker, followed by 200 mL of 1.5 mol / L dilute nitric acid solution. After stirring until completely dissolved, 352.34 g tetraethyl orthosilicate solution was gradually added dropwise. Rapid stirring continued for 2 h. The temperature was raised to 80 °C, and ammonia water was gradually added dropwise until the pH reached 9.3. Rapid stirring continued for 3 h, then stirring was stopped and the mixture was cooled to room temperature and allowed to stand for 5 h. The resulting solution was filtered, and the filtered solid was washed three times with deionized water. It was then dried in an oven at 150 °C for 8 h, and then calcined in a muffle furnace at 300 °C for 12 h to obtain a light blue powder with a Cu weight percentage of 5% and a Ni weight percentage of 10%. The catalyst was pressed into tablets and then sieved to a 10-20 mesh size to obtain the desired Cu-Ni / SiO2 catalyst.

[0096] Oxalate to ethanol: Weigh 20g of catalyst and load it onto the tray of reaction section (Y). After N2 replacement, H2 is introduced and the reaction proceeds for 1500 h. -1 The oxalate was reduced for 20 hours at a space velocity of 3.0 MPa and a temperature of 350°C, and then cooled to 200°C in preparation for feeding. The vaporized oxalate was mixed with H2 and entered the reactor from the lower end (1) of the reaction section, with the liquid hourly space velocity of the oxalate controlled at 0.8 h⁻¹. -1 The hydrogen-ester molar ratio is controlled at 60:1, and the reactor pressure is controlled at 3.0 MPa. After the reaction, the material enters the heat exchange unit for heat exchange separation. The low-boiling-point material enters the rectification section (Z) for atmospheric pressure rectification, and the high-boiling-point material enters the stripping tower (X) for further hydrogenation reaction. The bottom temperature of the rectification section is controlled at 150℃, and the top temperature of the rectification section is controlled at 102℃. The low-boiling-point methanol, ethanol, water and non-condensable gas (mainly unreacted H2) enter the condenser (8) from the top outlet (7) of the tower for condensation. The condensation temperature is controlled at 40℃. The low-boiling-point species enter the reflux tank (10) from the bottom outlet of the condenser. The unqualified product in the reflux tank is returned to the rectification tube for circulation rectification through (6). After the product is qualified, it is taken out from the outlet (11) of the reflux tank. H2 is taken out from the condenser (11) and recycled. High-boiling-point oxalate, methyl glycolate, and ethylene glycol are refluxed from heat exchanger (4) to the inlet (16) of the stripping section for reboiling reaction. The temperature of the reboiler in the stripping section is controlled at 203°C. After reboiling, the vaporized oxalate, methyl glycolate, and ethylene glycol enter the reaction section from the inlet (15), mix with H2 at the lower end (1) of the reaction section, and then enter the reaction section (Y) for reaction, so that the oxalate, methyl glycolate, and ethylene glycol are completely converted into ethanol. Samples are taken from (11) and (12) at 2-hour intervals, and the product composition is analyzed by gas chromatography using an FID detector. The conversion rate of oxalate and the selectivity of ethanol are calculated. The structure of the device is as follows. Figure 2 As shown, the reaction results are shown in Table 1.

[0097] Example 5

[0098] The catalyst preparation method was the same as in Example 1; the liquid hourly space velocity (LHSV) of the oxalate ester in the reaction section was adjusted to 1.2 h⁻¹. -1 The hydrogen-to-ester molar ratio was 150:1, the reactor pressure was 3.0 MPa, the reaction temperature was controlled at 205℃, and other conditions remained unchanged. Samples were taken from (11) and (12) at 2-hour intervals, and the product composition was analyzed by gas chromatography using an FID detector. The oxalate conversion rate and ethanol selectivity were calculated. The apparatus structure is as follows: Figure 2 As shown, the reaction results are shown in Table 1.

[0099] Example 6

[0100] The catalyst preparation method was the same as in Example 2; the liquid hourly space velocity (LHSV) of the oxalate ester in the reaction section was adjusted to 1.0 h⁻¹. -1The hydrogen-to-ester molar ratio was 120:1, the reactor pressure was 2.0 MPa, the reaction temperature was controlled at 195 °C, and other conditions remained unchanged. Samples were taken from (11) and (12) at 2-hour intervals, and the product composition was analyzed by gas chromatography using an FID detector. The oxalate conversion rate and ethanol selectivity were calculated. The device structure is as follows: Figure 2 As shown, the reaction results are shown in Table 1.

[0101] Example 7

[0102] The catalyst preparation method was the same as in Example 3; the liquid hourly space velocity (LHSV) of the oxalate ester in the reaction section was adjusted to 1.2 h⁻¹. -1 The hydrogen-to-ester molar ratio was 40:1, the reactor pressure was 2.5 MPa, the reaction temperature was controlled at 215 °C, and other conditions remained unchanged. Samples were taken from (11) and (12) at 2-hour intervals, and the product composition was analyzed by gas chromatography using an FID detector. The oxalate conversion rate and ethanol selectivity were calculated. The device structure is as follows: Figure 2 As shown, the reaction results are shown in Table 1.

[0103] Comparative Example 1

[0104] The catalyst preparation method was the same as in Example 1; a conventional tubular fixed-bed reactor was used, with a catalyst loading of 20g. The reactants entered from the top of the reactor, and the products exited from the bottom. The liquid hourly space velocity (LHSV) of the oxalate ester was controlled at 1.2 h⁻¹. -1 The hydrogen-to-ester molar ratio was 150:1, the reactor pressure was 3.0 MPa, and the reaction temperature was controlled at 205℃, with other conditions remaining constant. Samples were taken from the bottom outlet of the fixed bed at 2-hour intervals, and the product composition was analyzed by gas chromatography using an FID detector. The oxalate conversion rate and ethanol selectivity were calculated, and the results are shown in Table 1.

[0105] Comparative Example 2

[0106] The catalyst preparation method was the same as in Example 3; a conventional tubular fixed-bed reactor was used, with a catalyst loading of 20g. The reactants entered from the top of the reactor, and the products exited from the bottom. The liquid hourly space velocity (LHSV) of the oxalate ester was controlled at 1.2 h⁻¹. -1 The hydrogen-to-ester molar ratio was 40:1, the reactor pressure was 2.5 MPa, and the reaction temperature was controlled at 215 °C, with other conditions remaining constant. Samples were taken from the bottom outlet of the fixed bed at 2-hour intervals, and the product composition was analyzed by gas chromatography using an FID detector. The oxalate conversion rate and ethanol selectivity were calculated, and the results are shown in Table 1.

[0107] Table 1. Process for hydrogenation of oxalate esters to ethanol

[0108]

[0109]

[0110] As can be seen from Examples 1 to 7, the novel catalytic reactive distillation apparatus for producing ethanol from oxalate and hydrogen designed in this application can fully convert unreacted oxalate, intermediate product methyl glycol, and ethylene glycol through reflux in the upper distillation column, resulting in a complete reaction (the material after the reaction contains no oxalate, methyl glycol, or ethylene glycol), and achieves the separation of products and by-products.

[0111] The reaction apparatus and process conditions designed in this application can not only achieve a 100% conversion rate of oxalate and an ethanol selectivity of over 99%, but also enable preliminary separation of the reaction products, significantly reducing the energy consumption for subsequent purification and further contributing to a substantial reduction in the production cost of ethanol from oxalate.

[0112] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A catalytic reaction apparatus for the hydrogenation of oxalate ester to ethanol, characterized in that, The reaction apparatus includes a reactive distillation column, a condensation unit, a heating unit I, a heat exchange unit, and a heating unit II; The reactive distillation column comprises, from top to bottom, a connected distillation unit, a reaction unit, and a stripping unit. The distillation unit is equipped with a top outlet I and a reflux inlet I; The reaction unit is equipped with raw material inlet I and raw material inlet II; The top of the reaction unit is provided with outlet III for discharging the mixed product after the reaction; the distillation unit is also provided with reflux inlet II; The distillation unit is equipped with a bottom outlet II; The reaction unit is filled with a catalyst to catalyze the reaction of oxalate and hydrogen to produce a mixed product. The distillation unit is equipped with multiple trays for separating products with different boiling points from the mixed products; The distillation unit and the condensation unit are connected, and the condensation unit is used to condense the gaseous material separated by the distillation unit into a liquid material. The distillation unit is connected to the heating unit I. The distillation unit is used to vaporize the liquid material in the distillation unit by using the heat supplied by the heating unit I, and then continue to react with hydrogen. The discharge port III of the reaction unit is connected to the inlet of the heat exchange unit, and the heat exchange unit is used to separate the gas and liquid phases of the mixed products generated by the reaction unit. The liquid phase outlet of the heat exchange unit is connected to the reflux inlet II of the distillation unit, the gas phase outlet of the heat exchange unit is connected to the inlet I of the heating unit II, and the outlet of the heating unit II is connected to the reflux inlet I of the rectification unit. The heating unit II is used to supply heat to the rectification unit.

2. The catalytic reaction apparatus for the hydrogenation of oxalate ester to ethanol according to claim 1, characterized in that, The distillation unit is an atmospheric distillation column with a theoretical plate number of 20 to 50.

3. The catalytic reaction apparatus for the hydrogenation of oxalate ester to ethanol according to claim 1, characterized in that, The reaction unit is an isothermal tray reactor; the catalyst is spread evenly on the reactor tray; the distillation unit is an adiabatic vessel.

4. The catalytic reaction apparatus for the hydrogenation of oxalate ester to ethanol according to claim 1, characterized in that, The condensation unit includes a condenser and a reflux tank. The inlet of the condenser is connected to the top outlet I, the outlet of the condenser is connected to the inlet of the reflux tank, the outlet I of the reflux tank is connected to the reflux inlet I of the distillation unit, and the outlet II of the reflux tank is the product outlet. The heating unit I is a bottom reboiler I; the inlet of the reboiler I is connected to the bottom outlet II of the stripping unit, and the outlet of the reboiler I is connected to the feed inlet II of the reaction unit. The feed inlet I of the reaction unit is located at its bottom and is used for the mixed feeding of oxalate and hydrogen; the feed inlet II is located at the bottom of the reaction unit and is used for the return of the material from the distillation unit after reboiling and vaporization to the reaction unit.

5. The catalytic reaction apparatus for the hydrogenation of oxalate ester to ethanol according to claim 4, characterized in that, The outlet I of the reflux tank is connected to the inlet II of the heating unit II; The heat exchange unit is a cold and hot flow heat exchanger, where the cold flow is condensate and the hot flow is the mixed product generated by the reaction unit. The heating unit I or the heating unit II uses steam heating; The bottom of the distillation unit and the top of the reaction unit are connected by pipe I; the bottom of the reaction unit and the top of the stripping unit are connected by pipe II. Valve I is installed on pipe I; valve II is installed on pipe II.

6. A method for producing ethanol by hydrogenation of oxalate ester, characterized in that, The method is performed using the apparatus described in any one of claims 1 to 5.

7. The method for producing ethanol by hydrogenation of oxalate ester according to claim 6, characterized in that, The method includes the following steps: S1: Material I, containing oxalate and hydrogen, reacts with the catalyst in the reaction unit to generate material II; S2: Material II is separated by a distillation unit to obtain material III with a boiling point of 45~100℃ and material IV with a boiling point of 110~250℃. Material III is separated into a gas phase and a liquid phase containing ethanol after passing through a condensation unit; After material IV enters the distillation unit, it is reboiled and vaporized before reacting with hydrogen to produce ethanol. Material III contains hydrogen, ethanol, and methanol; Material IV contains methyl glycolate, ethylene glycol, and some oxalate. The hydrogen gas separated from material III is mixed and reacted with material I. And / or, the hydrogen separated from material III and the vaporized material IV are mixed and reacted.

8. The method for producing ethanol by hydrogenation of oxalate ester according to claim 6, characterized in that, In step S1, the hydrogen gas to oxalate ester molar ratio is 20~200:1; Alternatively, the liquid hourly space velocity of the oxalate ester is 0.1 to 1.5 h⁻¹. -1 ; Alternatively, the reaction temperature of the oxalate ester and hydrogen in the reaction unit is 170~250 °C, and the reaction pressure is 0.5~3.5 MPa.

9. A method for producing ethanol by hydrogenation of oxalate ester according to claim 6, characterized in that, In step S1, the hydrogen gas to oxalate ester molar ratio is 60~80:1; Alternatively, the liquid hourly space velocity of the oxalate ester is 0.3~0.8 h⁻¹. -1 ; Alternatively, the reaction temperature of the oxalate ester and hydrogen in the reaction unit is 180~220 °C, and the reaction pressure is 2.0~3.0 MPa.

10. A method for producing ethanol by hydrogenation of oxalate esters according to any one of claims 8 to 9, characterized in that, In step S2, the bottom temperature of the distillation unit is 100~150℃, the top temperature of the distillation unit is 65~110℃, and the pressure inside the distillation unit is 0.05~0.20MPa; the condensation temperature of the condensation unit is 10~60℃.

11. A method for producing ethanol by hydrogenation of oxalate esters according to any one of claims 8 to 9, characterized in that, In step S2, the bottom temperature of the distillation unit is 110~140℃, the top temperature of the distillation unit is 90~105℃, and the condensation temperature of the condensation unit is 30~60℃.

12. A method for producing ethanol by hydrogenation of oxalate esters according to any one of claims 8 to 9, characterized in that, In step S2, the temperature of the distillation unit's bottom column is 170~210℃; the temperature of the heating unit I after heating is 180~210℃.

13. A method for producing ethanol by hydrogenation of oxalate esters according to any one of claims 8 to 9, characterized in that, In step S2, the temperature of the distillation unit's bottom column is 170~210℃; the temperature of the heating unit I after heating is 190~200℃. The catalyst is selected from Cu-Ni / SiO2 catalysts; in the Cu-Ni / SiO2 catalyst, metallic Cu accounts for 5-10% of the total mass of the catalyst, metallic Ni accounts for 8-12% of the total mass of the catalyst, and the support is SiO2.

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