Propylene production method and production apparatus

Abstract

A method for dehydrating isopropanol to propylene, comprising a step of producing a propylene-containing product by dehydrating a raw material containing isopropanol in the presence of a dehydration catalyst containing aluminum oxide, wherein the raw material has a water content of 0.1 to 10.0 mass% (the total mass of the raw materials is taken as 100 mass%) and the sum of the content of C2 unsaturated impurities and the content of C3-C4 unsaturated impurities is 80 ppm or less (the total mass of the product is taken as 100 mass%).

Description

[Technical Field]

[0001] The present application belongs to the field of chemical industry and relates to a method for producing propylene by dehydration of isopropanol, a method for producing propylene from acetone including said method, and related apparatus. [Background technology]

[0002] Global demand for phenol has increased significantly in recent years. For example, global total phenol production capacity increased to 13.637 million tons per year in 2017, 47% higher than the global total phenol energy consumption in 2009. Statistics show that in recent years, multiple newly constructed phenol-acetone units have been built around the world, particularly in Asia and China. Current phenol production primarily uses the cumene oxidation process, in which acetone is a co-product. With the strong global demand for phenol, the rigid supply of co-produced acetone in existing phenol-ketone units is too large, creating the problem of regional and global acetone surpluses.

[0003] In view of the current situation of large-scale production capacity, large-scale market supply and demand, and low price of acetone in China and the world, as well as the shortage and high price of propylene, the integration of a method for producing propylene by hydrogenating and dehydrating acetone with a phenol-ketone unit can be used to solve the problems of low acetone prices and unsmooth sales, and can provide a technical scheme for adjusting the product ratio for the phenol-ketone unit, so as to significantly improve the market competitiveness of phenol and its downstream products, especially in the period when there is a large price difference between propylene and acetone, and achieve significant economic benefits.

[0004] CN 102690172A discloses a method for producing isopropanol by hydrogenating acetone, which aims to solve the problems encountered when producing isopropanol by hydrogenating acetone and removing impurities, especially water, from isopropanol, and includes converting acetone into isopropanol by hydrogenation, then removing water from the isopropanol by using diisopropylamine as an entrainer, and then removing heavy components to obtain a qualified isopropanol product.

[0005] CN 102728361A discloses a catalyst and its application for producing isopropanol by hydrogenation of acetone. The catalyst is 150-359m 2 / g and a BET specific surface area of ​​0.30 to 0.8 m 2 / g pore volume and 10 to 30 m 2 and 8-25% nickel with a total nickel content of / g.

[0006] CN 103772145B discloses a separation method useful for the production of isopropanol by hydrogenating acetone, which includes subjecting the acetone hydrogenation product to azeotropic distillation and extractive distillation to obtain high-purity isopropanol. Specifically, the method includes the steps of: (1) feeding the acetone hydrogenation product to a fractionation column for azeotropic distillation, removing an azeotropic mixture from the top of the column, removing heavy components from the bottom of the column, and removing the isopropanol product from the side of the column; (2) passing the azeotropic mixture removed from the top of the fractionation column to a stripping column and subjecting it to extraction and rectification using an extractant; removing a reflux of acetone and isopropanol from the top of the column and returning it to the reactor for recycling; and removing a concentrated aqueous solution of the extractant from the bottom of the column; and (3) sending material from the bottom of the stripping column to a dehydration column, removing the extractant from the bottom of the column and recycling it to the stripping column.

[0007] CN 103508833B discloses a method for producing propylene by dehydrating isopropanol, which involves contacting isopropanol with a catalyst under conditions for isopropanol dehydration to obtain propylene. The catalyst is prepared by the following method: preparing a gel system containing a template and an aluminum source; then removing mesoporous nanoalumina.

[0008] In "Thermodynamic analysis of reaction for producing propylene by dehydration of isopropanol," Modern Chemical Industry, volume 40, no. 6, Huixia Ma et al. state that, from the perspective of thermodynamic equilibrium, the isopropanol dehydration reaction is preferably carried out using a high-temperature, atmospheric pressure vapor-phase dehydration method. However, because the isopropanol dehydration reaction is still in the rate-controlling stage and does not reach thermodynamic equilibrium, the above references provide little guidance for carrying out the isopropanol dehydration reaction.

[0009] Chunyan Liu et al., in "Reaction for producing propylene by dehydration of isopropanol catalyzed with an acidic catalyst," Petrochemical Industry, Volume 19, No. 5, state that while simply increasing the reaction temperature can achieve a higher conversion of isopropanol, the effect is not ideal, as more side reactions result in a decrease in propylene selectivity. Summary of the Invention

[0010] The inventors of this application believe that, given the strong market demand for phenol and the excessive co-production of acetone by phenol-ketone units, the hydrogenation of acetone to produce propylene is an excellent technological route for adjusting the product scheme. However, the prior art methods for producing propylene by hydrogenating acetone have problems such as long process times, high catalyst conversion and selectivity, high energy consumption in the separation process, and high product purity requirements. Prior art methods employ a single-stage process for acetone hydrogenation and isopropanol dehydration, and there is no integrated process for producing isopropanol by hydrogenation / dehydration from acetone. The quality requirements for polymer-grade propylene products (GB / T 7716-2014) are high, resulting in the following problems: (1) The conversion and selectivity requirements for the single stage of acetone hydrogenation and isopropanol dehydration are high, or if the conversion and selectivity of either stage are low, the quality requirements for propylene cannot be met. (2) In particular, in the process for producing propylene by dehydration of isopropanol, the conversion and selectivity of a single stage directly affect the yield, product purity, and energy consumption for propylene purification and separation. Therefore, improving the conversion and selectivity of the process for producing propylene by dehydration of isopropanol is very important for improving the purity of the propylene product, reducing the consumption of isopropanol and acetone, and reducing the energy consumption for separation, etc. Therefore, improving the overall conversion and selectivity of the process for producing propylene from acetone, especially the conversion and selectivity of the process for producing propylene by dehydration of isopropanol, not only improves the purity of the propylene product, but also plays an important role in reducing the separation energy consumption and raw material consumption of the entire process.

[0011] Therefore, in view of the situation of excess acetone and shortage of propylene caused by the excessive supply of acetone co-production in the current phenol-ketone unit, the inventors of the present application believe that, while there is no integrated process for producing propylene from acetone or an integrated technology for combining propylene production with a phenol unit in the prior art, the integration of a process for producing propylene by hydrogenating acetone and then dehydrating it with a phenol-ketone unit can not only solve the problems of low price and insufficient marketability of acetone, but also provide a technical scheme for adjusting the product proportion for the phenol-ketone unit, and thus has obvious economic benefits.

[0012] After extensive research, the present inventors discovered that in the dehydration of isopropanol, in addition to the dehydration of isopropanol to produce propylene, there is a significant side reaction in which propylene is dimerized to produce heavy impurities such as propylene dimer. Furthermore, due to the high temperatures required for the dehydration, if the dehydration catalyst contains alumina, the propylene dimer may be cleaved to produce impurities such as light carbon components such as ethylene and heavy C4 components such as butene. Therefore, in the process of producing propylene by dehydration of isopropanol, if the dehydration catalyst contains alumina, the yield, product purity, and energy consumption of propylene purification and separation are directly affected by the dimer propylene and cracked C2 and C4 components in the reaction product. Therefore, the impurities generated by the side reaction reduce the quality of the produced propylene, and the produced propylene must be further purified to meet the requirements of the national standard for polymer-grade propylene.

[0013] The requirements for excellent and first-class products in the national standard GB / T 7716-2014 "Specifications for Propylene for Polymerization" are shown in Table 1.

[0014] [Table 1]

[0015] As can be seen from Table 1, the propylene content of first-grade polymer-grade propylene is required to be ≥ 99.2φ / % and the propylene content of superior grade propylene is required to be ≥ 99.6φ / %; the propylene content of national standard superior grade propylene is not only required to be ≥ 99.6%, but also the C2 ethylene content of national standard first-grade propylene is required to be ≤ 50 ppm, the acetylene content of national standard ≤ 5 ppm, and the C3-C4 unsaturated impurities content of national standard ≤ 20 ppm, and the C3-C4 unsaturated impurities content of national standard ≤ 5 ppm.

[0016] The inventors of the present application also found that the content of light components such as ethylene and acetylene in polymer-grade propylene products is strictly limited, and that if light component impurities are generated in the dehydration reaction process, a light component removal column of approximately 100 meters is required to separate the light component impurities, resulting in a significant increase in energy and material consumption in the subsequent separation process. One of the main problems that the present application aims to solve, and this is also one of the technical problems that exist in the prior art, is how to directly control the content of light component impurities such as ethylene and acetylene in the isopropanol dehydration reaction effluent within the content range required by specifications, reduce the energy and material consumption in the subsequent separation and purification section, and even completely omit the light component removal column or obtain polymer-grade propylene products at a lower cost.

[0017] The present inventors further conducted extensive research and found that when the dehydration catalyst contains alumina, adding a small amount of water can suppress the propylene dimerization reaction and decomposition of the dimerization product, thereby reducing impurity components. The present inventors also discovered that in such isopropanol dehydration reactions, there is a close correlation between the water content of the reaction starting materials and the amount of specific impurities produced. Furthermore, by adjusting and controlling the water content of the starting materials using a correlation equation under specific conversion conditions, it is possible to control the amount of impurities produced and reduce impurities that are difficult to separate during isopropanol dehydration. Furthermore, this correlation method of further adjusting and controlling reaction impurities by adjusting and controlling the water content of the starting materials can avoid the problem of increased side reactions caused by current operations that simply involve heating to increase isopropanol conversion. This method guides current industrial operations, simplifies reaction control procedures, effectively suppresses isopropanol dehydration side reactions, and reduces the difficulty of separating the subsequent propylene product. Furthermore, since water vapor causes the removal of aluminum from aluminum-containing catalysts and thus impairs the stability of the catalyst, the adverse effects on the catalyst under a larger water vapor atmosphere can be avoided, and the total energy consumption of the reaction can be reduced by controlling the amount of water added during the reaction.

[0018] The present application was completed based on the above findings.

[0019] In particular, the present application relates to the following aspects:

[0020] 1. A dehydration method comprising: a step (referred to as the dehydration step) of subjecting an isopropanol-containing starting material to a dehydration reaction in the presence of a dehydration catalyst containing alumina to produce a propylene-containing product; the starting material has a water content of 0.1 to 10.0% by mass (preferably, 1.0 to 9.0% by mass, more preferably 3.0 to 5.0% by mass, relative to 100% by mass of the total mass of the starting material); 10. A method for dehydration, characterized in that the product has a total content of C2 unsaturated impurities and C3-C4 unsaturated impurities of 80 ppm or less (preferably, 75 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, or 27 ppm or less, based on 100% by weight of the total weight of the product).

[0021] 2. The product is a C2 unsaturated impurity content of 50 ppm or less (preferably 30 ppm or less, 25 ppm or less, or 22 ppm or less, based on 100% by weight of the total weight of the product); and / or a C3-C4 unsaturated impurity content of 30 ppm or less (preferably 20 ppm or less, 10 ppm or less, or 5 ppm or less, based on 100% by weight of the total weight of the product); and / or a propylene content of 65.0 to 69.8% by mass (preferably 66.0 to 69.5% by mass, relative to 100% by mass of the total mass of the product); 10. The method of any one of the preceding or subsequent aspects, comprising:

[0022] 3. the starting material has an isopropanol content of 90.0 to 99.9% by mass (preferably 91.0 to 99.0% by mass, more preferably 92.0 to 97.0% by mass, relative to 100% by mass of the total mass of the starting material); and / or The dehydration method according to any one of the preceding or subsequent aspects, wherein the conversion rate of isopropanol is 96.0 to 99.9% (preferably 97.0 to 99.8%, more preferably 98.5 to 99.5%).

[0023] 4. The alumina-containing dehydration catalyst is alumina-containing solid acid catalysts; Preferably, it is at least one selected from amorphous silica-alumina and molecular sieves; More preferably, it is amorphous silica-alumina. Particularly preferred is amorphous silica-alumina having an alumina content of 1 to 30% by mass (preferably 1 to 15% by mass), with the remainder being silica; More particularly preferably, the dehydration method according to any one of the preceding or subsequent aspects is characterized in that the amorphous silica-alumina is subjected to a saturated steam treatment at 300 to 500°C.

[0024] 5. The operating conditions for the dehydration step are a reaction temperature of 150 to 450°C (preferably 200 to 350°C), a reaction pressure of 0.05 to 1.0 MPaG (preferably 0.1 to 0.5 MPaG), and a volumetric space velocity of 0.05 to 5.0 h -1 (Preferably 1 to 3 hours -1 10. The method of any one of the preceding or subsequent aspects, wherein

[0025] 6. further comprising the step of separating the isopropanol / water mixture (preferably an azeotrope) from the product, or Further, the following steps: (1) washing the product with an absorbent, preferably at least one selected from the group consisting of water and isopropanol, particularly water, to obtain a crude propylene product and a concentrated absorbent; (2) subjecting the crude propylene product to separation, preferably fractionation, to remove heavy components, preferably only heavy components, to obtain purified propylene; (3) separating the strong absorption liquid and preferably subjecting it to rectification to obtain an isopropanol / water mixture, preferably an azeotropic mixture; 10. The method of any one of the preceding or subsequent aspects, comprising:

[0026] 7. The method of any one of the preceding or subsequent aspects, wherein the mixture has a water content of 5 to 90% by mass (preferably 10 to 80%, 10 to 50%, or 10 to 20%, more preferably 12 to 13% by mass), based on 100% by mass of the total mass of the mixture.

[0027] 8. The method of any one of the preceding or subsequent aspects, further comprising a step of recycling at least a portion (preferably at least 50%, at least 80%, at least 90%, or substantially 100% by weight) of the mixture to the dehydration step (referred to as the recycling step).

[0028] 9.

[0023] The method of any one of the preceding or subsequent aspects, wherein in the recycling step, at least a portion of the mixture is mixed with the starting material of the dewatering step, optionally supplemented with an additional amount of water, to adjust (e.g., increase or decrease) the moisture content of the starting material to a predetermined level.

[0029] 10. further comprising measuring the content of C3-C4 unsaturated impurities in the product and comparing the measured content (in ppm) with a predetermined value (e.g., 20 ppm, 10 ppm, or 5 ppm) relative to 100% by mass of the total mass of the product; If the measured content is greater than the predetermined value, measure the conversion rate of isopropanol to obtain a measured conversion rate (set as C, in %); (1) if the measured value C is 96.0% to 99.0%, the water content of the starting material is increased (preferably by 0.01 to 30 times, 0.01 to 20 times, 0.01 to 10 times, 0.01 to 5 times, 0.01 to 1 time, 0.01 to 0.5 times, 0.01 to 0.3 times, 0.01 to 0.2 times, or 0.01 to 0.1 times), provided that the water content after the increase is in the range of 0.1 to 3.0% by mass (based on 100% by mass of the total mass of the starting material); Preferably, when a plane Cartesian coordinate system is established with the abscissa representing the conversion rate of isopropanol (unit: %) (starting point: 96.0, end point: 99.0), the ordinate representing the water content of the starting material (unit: %) (starting point: 0.1, end point: 3.0), and the origin of the coordinate (0,0), a straight line section (line segment) is drawn from the coordinate (96.0,0.1) to the coordinate (99.0,3.0), and the coordinate of the measured value C on the straight line section is set as (C, A1), where A1 represents the water content value corresponding to the measured value C on the straight line section. The increased water content value is selected to be a value in the range of A1 to 3.0, preferably a value in the range of A1 to A1 + (3.0 - A1) / 2, (2) if the measured value C is 99.0% to 99.5%, increasing the water content of the starting material (preferably by 0.01 to 2 times, 0.01 to 1 time, 0.01 to 0.5 times, 0.01 to 0.3 times, 0.01 to 0.2 times, or 0.01 to 0.1 times), provided that the water content after the increase is in the range of 3.0 to 5.0 mass% (based on 100 mass% of the total mass of the starting material); Preferably, when a plane Cartesian coordinate system is established with the abscissa representing the conversion rate of isopropanol (unit: %) (starting point: 99.0, end point: 99.5), the ordinate representing the water content of the starting material (unit: %) (starting point: 3.0, end point: 5.0), and the origin of the coordinate (0,0), a straight line section (line segment) is drawn from the coordinate (99.0,3.0) to the coordinate (99.5,5.0), and the coordinate of the measured value C on the straight line section is set as (C, A2), where A2 represents the water content value corresponding to the measured value C on the straight line section. The increased water content value is selected to be a value in the range of A2 to 5.0, preferably a value in the range of A2 to A2 + (5.0 - A2) / 2, (3) if the measured value C is 99.5% to 99.9%, increasing the water content of the starting material (preferably by 0.01 to 2 times, 0.01 to 1 time, 0.01 to 0.5 times, 0.01 to 0.3 times, 0.01 to 0.2 times, or 0.01 to 0.1 times), provided that the water content after the increase is in the range of 5.0 to 10.0 mass% (preferably 5.0 to 9.0 mass%) (relative to 100 mass% of the total mass of the starting material); Preferably, when a plane Cartesian coordinate system is established with the abscissa representing the conversion rate of isopropanol (unit: %) (starting point: 99.5, end point: 99.9), the ordinate representing the water content of the starting material (unit: %) (starting point: 5.0, end point: 10.0), and the origin being coordinate (0,0), a straight line section (line segment) is drawn from coordinate (99.5,5.0) to coordinate (99.9,10.0), and the coordinate of the measured value C on the straight line section is set as (C, A3), where A3 represents the water content value corresponding to the measured value C on the straight line section. The increased water content value is selected to be a value in the range of A3 to 10.0 (preferably A3 to 9.0), and preferably the increased water content value is selected to be a value in the range of A3 to A3 + (10.0 - A3) / 2 (preferably A3 to A3 + (9.0 - A3) / 2). 10. The method of any one of the preceding or subsequent aspects, wherein

[0030] 11. The method further comprises measuring the C2 unsaturated impurity content of the product and comparing the measured content (in ppm) with a predetermined value (e.g., 50 ppm, 30 ppm, 25 ppm, or 22 ppm) relative to 100% by weight of the total weight of the product, and if the measured content is greater than the predetermined value, measuring the conversion of isopropanol to obtain a measured conversion value (set as D, in %); (1) if the measured value D is 96.0% to 99.0%, increasing the water content of the starting material (preferably by 0.01 to 50 times, 0.01 to 20 times, 0.01 to 10 times, 0.01 to 5 times, 0.01 to 1 time, 0.01 to 0.5 times, 0.01 to 0.3 times, 0.01 to 0.2 times, or 0.01 to 0.1 times), provided that the water content after the increase is in the range of 0.1 to 5.0% by mass (based on 100% by mass of the total mass of the starting material); Preferably, when a plane Cartesian coordinate system is established with the abscissa representing the conversion rate of isopropanol (unit: %) (starting point: 96.0, end point: 99.0), the ordinate representing the water content of the starting material (unit: %) (starting point: 0.1, end point: 5.0), and the origin of the coordinate (0,0), a straight line section (line segment) is drawn from the coordinate (96.0,0.1) to the coordinate (99.0,5.0), and the coordinate of the measured value D on the straight line section is set as (D, B1), where B1 represents the water content value corresponding to the measured value D on the straight line section. The increased water content value is selected to be a value in the range of B1 to 5.0, preferably a value in the range of B1 to B1 + (5.0 - B1) / 2, (2) if the measured value D is 99.0% to 99.9%, the water content of the starting material is increased (preferably by 0.01 to 3 times, 0.01 to 2 times, 0.01 to 1 time, 0.01 to 0.5 times, 0.01 to 0.3 times, 0.01 to 0.2 times, or 0.01 to 0.1 times), provided that the water content after the increase is in the range of 5.0 to 10.0 mass% (preferably 5.0 to 9.0 mass%) (relative to 100 mass% of the total mass of the starting material); Preferably, when a plane Cartesian coordinate system is established with the abscissa representing the conversion rate of isopropanol (unit: %) (starting point: 99.0, end point: 99.9), the ordinate representing the water content of the starting material (unit: %) (starting point: 5.0, end point: 10.0), and the origin of the coordinate (0,0), a straight line section (line segment) is drawn from the coordinate (99.0,5.0) to the coordinate (99.9,10.0), and the coordinate of the measured value D on the straight line section is set as (D, B2), where B2 represents the water content value corresponding to the measured value D on the straight line section. The increased water content value is selected to be a value in the range of B2 to 10.0 (preferably B2 to 9.0), and preferably the increased water content value is selected to be a value in the range of B2 to B2 + (10.0 - B2) / 2 (preferably B2 to B2 + (9.0 - B2) / 2). 10. The method of any one of the preceding or subsequent aspects, wherein

[0031] 12. A method for producing propylene, comprising: subjecting acetone as a starting material to a hydrogenation reaction in the presence of a hydrogenation catalyst to produce an isopropanol-containing product; separating the isopropanol-containing product to obtain a hydrogen-containing gas and an isopropanol-containing liquid; Separating the isopropanol-containing liquid to obtain isopropanol; dehydrating the isopropanol to produce a propylene-containing product by the dehydration process of any one of the preceding or subsequent embodiments (referred to as the dehydration step); washing the propylene-containing product with an absorbent to obtain a crude propylene product and a concentrated absorbent; separating the concentrated absorption liquid to obtain an isopropanol / water azeotrope; separating and removing heavy components from the crude propylene product to obtain purified propylene; A method for producing propylene, comprising:

[0032] 13.

[0023] The method for producing propylene of any one of the preceding or subsequent embodiments, further comprising recycling at least a portion (preferably at least 50%, at least 80%, at least 90%, or substantially 100% by weight) of the isopropanol / water azeotrope to the dehydration step.

[0033] 14. A propylene production apparatus, an acetone hydrogenation reactor; a hydrogenation product gas-liquid separator; A fractionating tower; an isopropanol dehydration reactor; a propylene absorption and separation tower; an azeotropic distillation column; a crude propylene heavy fractionator; and A manufacturing apparatus comprising: The acetone hydrogenation reactor is configured to hydrogenate acetone as a starting material in the presence of a hydrogenation catalyst to produce an isopropanol-containing product; the hydrogenation product gas-liquid separator is configured to separate the isopropanol-containing product to obtain a hydrogen-containing gas and an isopropanol-containing liquid; the fractionation column is configured to separate the isopropanol-containing liquid to obtain isopropanol; the isopropanol dehydration reactor is configured to dehydrate isopropanol as a starting material in the presence of an alumina-containing dehydration catalyst to produce a propylene-containing product; the propylene absorption separation column is configured to wash the propylene-containing product with an absorbent to obtain a crude propylene product and a strong absorbent; the azeotropic distillation column is configured to separate the strong absorption liquid to obtain an isopropanol / water azeotrope; the crude propylene heavies fractionator is configured to separate and remove heavy components from the crude propylene product to obtain purified propylene; The upper end and / or upper material outlet of the azeotropic distillation column is connected to the material inlet of the isopropanol dehydration reactor. A manufacturing apparatus comprising:

[0034] 15. a product outlet of the isopropanol dehydration reactor is provided with at least two measuring devices, at least one comparator, and at least one controller; At least one of the at least two measuring devices is configured to measure the C3-C4 unsaturated impurity content and / or the C2 unsaturated impurity content of the product to obtain a content measurement, and at least one is configured to measure the conversion of isopropanol to obtain a conversion measurement; the at least one comparator is configured to compare the measured value with a preset value and issue a command to the at least one controller based on the comparison result and the measured value of conversion rate; the at least one controller is configured to execute the instructions to increase the water content of the starting material of the isopropanol dehydration reactor. 10. The manufacturing apparatus of any one of the preceding or subsequent aspects.

[0035] Alternatively, the present application also relates to the following aspects.

[0036] 1. A method for dehydrating isopropanol, comprising adding a reaction promoter during the dehydration reaction of isopropanol, the reaction promoter being a mixture of an alkanol and water.

[0037] 2. 10. The method of any one of the preceding or subsequent aspects, wherein the alkanol is at least one selected from isopropanol, n-propanol, methanol, and ethanol.

[0038] 3. The method of any one of the preceding or subsequent aspects, wherein the mass content of the alkanol in the mixture of alkanol and water is from 10% to 90% by mass, preferably from 50% to 88% by mass.

[0039] 4. The method of any one of the preceding or subsequent aspects, wherein the reaction promoter is added in an amount of 0.01 to 15.0%, preferably 1 to 10%, and more preferably 1.5 to 5.5%, by weight of the isopropanol starting material.

[0040] 5. 10. The method of any one of the preceding or subsequent aspects, further comprising adding a catalyst during the isopropanol dehydration reaction, the catalyst being at least one selected from amorphous silica-alumina, ZSM-5 molecular sieve, and a resin catalyst.

[0041] 6. The conditions for the dehydration reaction of isopropanol are a temperature of 150 to 450°C, a pressure of 0.05 to 1.0 MPaG, and a reaction time of 0.05 to 5.0 h. -1 10. The method of any one of the preceding or subsequent aspects, wherein the catalyst volumetric space velocity is

[0042] 7. A method for producing propylene by dehydrating isopropanol, the method comprising the steps of: an isopropanol dehydration reaction step; an absorption and separation step of an isopropanol dehydration product; and a crude propylene purification step, wherein a reaction promoter is added during the isopropanol dehydration reaction step, and the reaction promoter is a mixture of an alkanol and water.

[0043] 8. 10. The process of any one of the preceding or subsequent aspects, wherein the alkanol is at least one selected from isopropanol, n-propanol, methanol, and ethanol.

[0044] 9. The method of any one of the preceding or subsequent aspects, wherein the mass content of the alkanol in the mixture of alkanol and water is from 10% to 90% by mass.

[0045] 10. The process of any one of the preceding or subsequent aspects, wherein the reaction promoter is added in an amount of 0.01 to 15.0% by weight of the isopropanol starting material.

[0046] 11. The process of any one of the preceding or subsequent embodiments, wherein the reaction promoter is an azeotrope of an alkanol and water.

[0047] 12. 10. The process according to any one of the preceding or subsequent aspects, wherein an absorbent is added during absorption separation of the isopropanol dehydration product, and the absorbent is at least one selected from isopropanol, n-propanol, methanol, ethanol, and water.

[0048] 13. 10. The method of any one of the preceding or subsequent aspects, wherein the absorbent is water, isopropanol, or a mixture of isopropanol and water in any ratio.

[0049] 14. A method for producing propylene from acetone, the method comprising, in order, an acetone hydrogenation step, a hydrogenation product gas-liquid separation step, an isopropanol purification step, and a method for producing propylene by dehydration of isopropanol according to any one of the preceding or subsequent aspects.

[0050] 15. 10. The method of any one of the preceding or subsequent aspects, wherein the alkanol is at least one selected from isopropanol, n-propanol, methanol, and ethanol.

[0051] 16. The method of any one of the preceding or subsequent aspects, wherein the mass content of the alkanol in the mixture of alkanol and water is from 10% to 90% by mass.

[0052] 17. The method of any one of the preceding or subsequent aspects, wherein the reaction promoter is added in an amount of 0.01 to 15.0% by weight of the isopropanol starting material.

[0053] 18. 10. The method of any one of the preceding or subsequent aspects, wherein the reaction promoter is an azeotrope of an alkanol and water.

[0054] 19. 10. The method of any one of the preceding or subsequent aspects, wherein the absorbent is at least one selected from isopropanol, n-propanol, methanol, ethanol, and water.

[0055] 20. Acetone hydrogenation is carried out at a temperature of 100 to 200°C, a pressure of 0.5 to 6.0 MPaG, and for 0.05 to 15 hours. -1 and a molar ratio of hydrogen to acetone of from 2:1 to 15:1.

[0056] twenty one. 10. The method of any one of the preceding or subsequent aspects, wherein in the gas-liquid separation process of the acetone hydrogenation product, the resulting gas is hydrogen, which is recycled, and the liquid product contains small amounts of unreacted acetone and heavy component by-products, which are removed in a fractionation column to obtain purified isopropanol.

[0057] twenty two. 1. A processing system for producing propylene from acetone, comprising: an acetone starting material storage tank; an acetone hydrogenation reactor; a gas-liquid separator; a fractionation column; an isopropanol storage tank; an isopropanol dehydration reactor; an absorption separation column; a compressor; and a crude propylene purification column, which are connected in series; wherein the absorption separation column is provided with an absorbent inlet, the bottom outlet of which is connected to an azeotropic distillation column, and the azeotropic mixture outlet of the azeotropic distillation column is connected to the inlet of the isopropanol dehydration reactor.

[0058] twenty three. 10. The treatment system of any one of the preceding or subsequent aspects, wherein a product outlet at the bottom of the azeotropic distillation column is further connected to an inlet of an absorption-separation column, and wherein the product is added to the absorption-separation column in parallel with the absorbent entering the absorption-separation column.

[0059] twenty four.

[0023] The processing system of any one of the preceding or subsequent aspects, wherein the gas outlet of the gas-liquid separator is connected to a compressor and ultimately to an acetone hydrogenation reactor, and wherein hydrogen obtained by gas-liquid separation is used as make-up hydrogen for acetone hydrogenation.

[0060] twenty five. 10. The processing system of any one of the preceding or subsequent aspects, wherein the overhead light components product outlet of the fractionation column is connected to an acetone starting material storage tank and unreacted acetone is recycled.

[0061] 26. 10. The processing system of any one of the preceding or subsequent aspects, wherein the acetone hydrogenation reactor is a tubular fixed-bed reactor, the tubes being packed with a catalyst, and a heat removal medium being introduced outside the tubes.

[0062] 27. 10. The processing system of any one of the preceding or subsequent aspects, wherein the isopropanol dehydration reactor is a tubular fixed-bed reactor, the tubes being packed with a catalyst and the heat supply medium being introduced outside the tubes. [Brief explanation of the drawings]

[0063] [Figure 1] 1 shows a schematic diagram of a processing system for producing propylene from acetone in accordance with the present application. DETAILED DESCRIPTION OF THE INVENTION

[0064] Although the present application will be described in detail below with reference to embodiments thereof, it should be noted that the scope of the present application is not limited by those embodiments but is defined by the appended claims.

[0065] All publications, patent applications, patents and other references cited in this specification are incorporated by reference in their entirety.Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art.In case of discrepancy, the contents described in this specification, including definitions, shall prevail.

[0066] In this specification, when a material, substance, method, process, apparatus, component, or the like is described as "commonly known to those skilled in the art," "prior art," or the like, it should be understood that the material, substance, method, process, apparatus, and component in question covers not only those conventionally used in the relevant technical field at the time of filing of this application, but also those that are no longer in general use but that will become generally known in the relevant technical field as being suitable for a similar purpose.

[0067] In the context of this application, unless otherwise stated, all percentages, parts, ratios, etc. are expressed by weight and all pressures given are gauge pressures.

[0068] In the context of this application, C2 unsaturated impurities include ethylene and acetylene, and C3-C4 unsaturated impurities include methylacetylene, propadiene, butene, butadiene, diacetylenes, etc., in particular methylacetylene, propadiene, butene and butadiene.

[0069] In the context of this application, the content (mass%) of isopropanol (unreacted) in the product can be measured online directly using an infrared spectrometer on the gas at the reactor outlet, or by gas chromatography by condensing the reaction effluent at the outlet, collecting the condensed liquid, and analyzing the isopropanol content (mass%) in the liquid product. The water content of the isopropanol starting material can also be measured by sampling the starting material at the reactor inlet and measuring the water content (mass%) of the starting material using gas chromatography or a moisture meter.

[0070] In the context of this application, the isopropanol content A (% by weight) of the product is measured using an infrared spectrometer, the water content B (% by weight) of the starting material is measured using a moisture meter, and the isopropanol conversion X is: X=A / (1-B) It is calculated as:

[0071] In the present application, the isopropanol content C (mass%) of the starting material and the isopropanol content D (mass%) of the product condensate are measured by gas chromatography, the feed amount M (g unit) of the starting material can be calculated from the pump flow rate and sampling time, the mass N (g unit) of the condensate (liquid) can be determined by weighing, and the isopropanol conversion X can be calculated by the following formula: X=(DN) / (CM) It is calculated as follows.

[0072] In the context of this application, any two or more embodiments of this application can be arbitrarily combined, and the resulting technical solution forms part of the initial disclosure of this application and falls within the scope of this application.

[0073] The endpoints of any numerical range and any numerical value described in the context of this application should not be construed as being limited to the exact range or value, but should also encompass values ​​close to said range or value. Furthermore, with respect to any numerical range described herein, any combination between the endpoints of the range, between each endpoint and any specific value within the range, or between any two specific values ​​within the range, can be made to provide one or more new numerical ranges, which new numerical ranges should be considered to be specifically set forth in this application.

[0074] According to one embodiment of the present application, the present invention relates to a dehydration process, such as a process for producing propylene by dehydrating isopropanol.

[0075] According to one embodiment of the present application, the dehydration method includes a step of subjecting an isopropanol-containing starting material to a dehydration reaction in the presence of a dehydration catalyst containing alumina to produce a propylene-containing product, referred to as the dehydration step. According to the present application, the technical effect of the present application is particularly pronounced when the dehydration catalyst contains alumina.

[0076] According to one embodiment of the present application, the water content of the starting material is 0.1 to 10.0 mass%, preferably 1.0 to 9.0 mass%, and more preferably 3.0 to 5.0 mass%, based on 100 mass% of the total mass of the starting material. According to the present application, if the water content is less than 0.1 mass%, the total content of C2 unsaturated impurities and C3-C4 unsaturated impurities in the product exceeds the upper limit of the numerical range specified in the present application, and the desired effects of the present application, such as a significant reduction in the impurity content, cannot be achieved. Furthermore, if the water content exceeds 10.0 mass%, not only does the energy consumption in the dehydration step increase, but the total content of C2 unsaturated impurities and C3-C4 unsaturated impurities in the product exceeds the upper limit of the numerical range specified in the present application, and the desired effects of the present application, such as a significant reduction in the impurity content, cannot be achieved.

[0077] According to one embodiment of the present application, the sum of the content of C2 unsaturated impurities and the content of C3-C4 unsaturated impurities in the product is 80 ppm or less, preferably 75 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, or 27 ppm or less, based on 100% by mass of the total product. Preferably, the product has a C2 unsaturated impurity content of 50 ppm or less, preferably 30 ppm or less, 25 ppm or less, or 22 ppm or less, based on 100% by mass of the total product. Preferably, the product has a C3-C4 unsaturated impurity content of 30 ppm or less, preferably 20 ppm or less, 10 ppm or less, or 5 ppm or less, based on 100% by mass of the total product.

[0078] According to one embodiment of the present application, the propylene content of the product is 65.0 to 69.8 mass %, preferably 66.0 to 69.5 mass %, relative to 100 mass % of the total mass of the product.

[0079] According to one embodiment of the present application, the isopropanol content of the starting material is 90.0 to 99.9 mass%, preferably 91.0 to 99.0 mass%, more preferably 92.0 to 97.0 mass%, based on 100 mass% of the total mass of the starting material. In addition to isopropanol and water, the starting material may contain other components, such as acetone or methanol, retained from the acetone hydrogenation reaction.

[0080] According to one embodiment of the present application, the conversion rate of isopropanol is 96.0 to 99.9%, preferably 97.0 to 99.8%, and more preferably 98.5 to 99.5%, from the viewpoint of significantly achieving the effects of the present application.

[0081] According to one embodiment of the present application, the dehydration catalyst may be any solid acid catalyst known in the art capable of dehydrating isopropanol, but must contain alumina. The desired effects of the present application are most pronounced when the dehydration catalyst contains alumina. The dehydration catalyst is preferably at least one selected from amorphous silica-alumina and molecular sieves, more preferably amorphous silica-alumina. Here, the amorphous silica-alumina is particularly preferably amorphous silica-alumina having an alumina content of 1 to 30% by mass (preferably 1 to 15% by mass), with the remainder being silica. The amorphous silica-alumina may be commercially available or may be produced by a conventional method. More preferably, the amorphous silica-alumina is amorphous silica-alumina treated with saturated steam at 300 to 500°C. A method for producing amorphous silica-alumina includes, for example, treating commercially available amorphous silica-alumina pellets with an alumina content of 1 to 15% by mass in a saturated steam atmosphere at 300 to 500°C for 5 to 10 hours. The catalyst exhibits excellent dehydration activity, selectivity, and long-term stability under very mild conditions in the isopropanol dehydration process. Other examples of dehydration catalysts include the core-shell alumina catalyst described in CN102451674.

[0082] According to one embodiment of the present application, the reaction temperature in the dehydration step is 150 to 450°C, preferably 200 to 350°C.

[0083] According to one embodiment of the present application, the reaction pressure in the dehydration step is 0.05 to 1.0 MPaG, preferably 0.1 to 0.5 MPaG.

[0084] According to one embodiment of the present application, the volumetric space velocity in the dehydration step is 0.05 to 5.0 h -1 , preferably 1 to 3 hours -1 is.

[0085] According to one embodiment of the present application, the dehydration method further comprises the step of separating an isopropanol / water mixture, preferably an azeotropic mixture, from the product.

[0086] According to one embodiment of the present application, the dehydration method further comprises the steps of: (1) A step of washing the product with an absorbent to obtain a crude propylene product and a concentrated absorbent, wherein the absorbent is a solvent capable of absorbing the water-soluble components in the isopropanol dehydration product, and is preferably water, isopropanol, or a mixture of isopropanol and water in any ratio, and the absorbent is a dilute absorbent before being added, and becomes a concentrated absorbent after absorbing the soluble components. (2) Separating the crude propylene product to remove heavy components and obtain purified propylene. Here, the separation is preferably performed by fractionation. Additionally, according to the present application, the content of light components in the obtained crude propylene product is very low due to the isopropanol dehydration method of the present application. Therefore, a purified propylene product, particularly a purified propylene product meeting the requirements of national polymer grade propylene, can preferably be obtained by simply removing heavy components from the crude propylene product by separation. According to this preferred embodiment, the separation includes only the step of removing heavy components, and does not need to include the step of removing light components, as typically required in the prior art. As used herein, "heavy components" typically refer to hydrocarbon substances having four or more carbons, particularly C4 unsaturated impurities, and "light components" typically refer to hydrocarbon substances having two or fewer carbons, particularly C2 unsaturated impurities. (3) Separating the concentrated absorption liquid to obtain an isopropanol / water mixture, preferably by rectification, particularly azeotropic rectification.

[0087] According to one embodiment of the present application, in the dehydration method, the mixture has a water content of 5 to 90 mass%, preferably 10 to 80 mass%, 10 to 50 mass%, or 10 to 20 mass%, more preferably 12 to 13 mass%, relative to 100 mass% of the total mass of the mixture.

[0088] According to one embodiment of the present application, the present invention further includes a step of recycling at least a portion of the mixture to the dehydration step (referred to as the "recycle step"). Here, the "at least a portion" is preferably 50% by mass or more, 80% by mass or more, 90% by mass or more, or substantially 100% by mass (i.e., substantially all of the mixture is recycled). By recycling the mixture, particularly the azeotropic mixture, to the dehydration step, the water content of the starting material can be flexibly adjusted, significantly reducing the overall energy consumption of the dehydration method. For this purpose, in the recycle step, it is preferable to mix at least a portion of the mixture with the starting material of the dehydration step, and optionally add additional water to adjust (e.g., increase or decrease) the water content of the starting material to a predetermined level. The present application does not impose any particular limitations on the method of mixing the mixture with the starting material (optionally including additional water), as long as these materials are sufficiently mixed. To adjust the water content of the starting material, these materials are typically mixed before the dehydration reaction of the starting material (e.g., before entering the dehydration reactor).

[0089] The present inventors have found that the water content of the isopropanol starting material during the reaction is closely related to the conversion rate of isopropanol and the content of C3-C4 unsaturated impurities or C2 unsaturated impurities in the product. Specifically, when the reaction conversion rate exceeds 96%, for example, by increasing the reaction temperature, the higher the reaction conversion rate, the higher the content of C3-C4 unsaturated impurities or C2 unsaturated impurities in the reaction product. To this end, the present application also relates to a scheme for controlling such impurities in the following embodiments.

[0090] According to one embodiment of the present application, the dehydration method further comprises a step of measuring the content of C3-C4 unsaturated impurities in the product. The content can be measured, for example, by an infrared spectroscopic analyzer. Typically, the measurement is performed at the reaction product outlet of the dehydration reactor. The content measurement can be performed continuously, intermittently, online, or offline, and is not particularly limited.

[0091] According to this embodiment of the present application, the content is measured to obtain a content measurement (unit: ppm). The content measurement is then compared with a preset content value, such as 20 ppm, 10 ppm, or 5 ppm (based on 100% by weight of the total product weight). The preset value represents the maximum level of C3-C4 unsaturated impurities in the reaction product that is acceptable to those skilled in the art.

[0092] According to this embodiment of the present application, when the measured content value is greater than a preset value (trigger condition) by the comparison, the conversion rate of isopropanol is measured to obtain a measured conversion rate value (set as C, unit %). Typically, the conversion rate measurement is performed at the reaction product outlet of the dehydration reactor. The conversion rate measurement can be performed continuously, intermittently, online, or offline, and is not particularly limited. Furthermore, according to the present application, the content measurement and the conversion rate measurement can be performed simultaneously or sequentially in a certain order, and are not particularly limited. However, from the viewpoint of efficiency, the conversion rate measurement is usually performed when the trigger condition is satisfied.

[0093] According to this embodiment of the present application, if the measured value C is between 96.0% and 99.0%, the water content of the starting material is increased, provided that the increased water content is in the range of 0.1 to 3.0% by mass (based on 100% by mass of the total mass of the starting material), where the magnitude (amplitude) of the increase is typically 0.01 to 30 times, 0.01 to 20 times, 0.01 to 10 times, 0.01 to 5 times, 0.01 to 1 time, 0.01 to 0.5 times, 0.01 to 0.3 times, 0.01 to 0.2 times, or 0.01 to 0.1 times. According to the present application, preferably, when a plane Cartesian coordinate system is established with the abscissa representing the isopropanol conversion rate (unit: %) (starting point: 96.0, end point: 99.0) and the ordinate representing the water content (unit: %) of the starting material (starting point: 0.1, end point: 3.0), and the coordinate (0,0) representing the origin, a straight line segment is drawn from the coordinate (96.0,0.1) to the coordinate (99.0,3.0), and the coordinate of the measured value C on the straight line segment is set as (C, A1), where A1 represents the water content value corresponding to the measured value C on the straight line segment. The increased water content value is selected to be a value in the range of A1 to 3.0, and preferably a value in the range of A1 to A1 + (3.0 - A1) / 2. The increased water content value is typically selected to be A1 or its vicinity. According to the present invention, when the conversion rate of isopropanol is changed by changing the reaction temperature (e.g., by increasing the reaction temperature), the content of C3-C4 unsaturated impurities in the reaction product can be controlled to 10 ppm or less, preferably 5 ppm or less, by this control method.

[0094] According to this embodiment of the present application, if the measured value C is between 99.0% and 99.5%, the water content of the starting material is increased, provided that the increased water content is in the range of 3.0 to 5.0% by mass (based on 100% by mass of the total mass of the starting material), where the magnitude (amplitude) of the increase is typically 0.01 to 2 times, 0.01 to 1 time, 0.01 to 0.5 times, 0.01 to 0.3 times, 0.01 to 0.2 times, or 0.01 to 0.1 times. According to the present application, preferably, when a plane Cartesian coordinate system is established with the abscissa representing the isopropanol conversion rate (unit: %) (starting point: 99.0, end point: 99.5) and the ordinate representing the water content (unit: %) of the starting material (starting point: 3.0, end point: 5.0), and the coordinate (0,0) representing the origin, a straight line segment is drawn from the coordinate (99.0,3.0) to the coordinate (99.5,5.0), and the coordinate of the measured value C on the straight line segment is set as (C, A2), where A2 represents the water content value corresponding to the measured value C on the straight line segment. The increased water content value is selected to be a value in the range of A2 to 5.0, preferably a value in the range of A2 to A2 + (5.0 - A2) / 2. The increased water content value is typically selected to be A2 or its vicinity. According to the present invention, when the conversion rate of isopropanol is changed by changing the reaction temperature (e.g., by increasing the reaction temperature), the content of C3-C4 unsaturated impurities in the reaction product can be controlled to 10 ppm or less, preferably 5 ppm or less, by this control method.

[0095] According to this embodiment of the present application, if the measured value C is between 99.5% and 99.9%, the water content of the starting material is increased, provided that the water content after the increase is in the range of 5.0 to 10.0% by mass (preferably 5.0 to 9.0% by mass) (based on 100% by mass of the total mass of the starting material), where the magnitude (amplitude) of the increase is typically 0.01 to 2 times, 0.01 to 1 time, 0.01 to 0.5 times, 0.01 to 0.3 times, 0.01 to 0.2 times, or 0.01 to 0.1 times. According to the present application, preferably, when a plane Cartesian coordinate system is established with the abscissa representing the conversion rate of isopropanol (unit: %) (starting point: 99.5, end point: 99.9), the ordinate representing the water content of the starting material (unit: %) (starting point: 5.0, end point: 10.0), and the origin being coordinate (0,0), a straight line section (line segment) is drawn from coordinate (99.5,5.0) to coordinate (99.9,10.0), and the coordinate of measured value C on said straight line section is set as (A3, set as C), where A3 represents the water content value corresponding to measured value C on said straight line section, a value in the range of A3 to 10.0 (preferably A3 to 9.0) is selected as the increased water content value, and preferably a value in the range of A3 to A3 + (10.0 - A3) / 2 (preferably A3 to A3 + (9.0 - A3) / 2) is selected as the increased water content value. The value of the water content after the increase is typically selected to be A3 or its vicinity. According to the present application, when the conversion rate of isopropanol is changed by changing the reaction temperature (e.g., by increasing the reaction temperature), this control method can control the content of C3-C4 unsaturated impurities in the reaction product to 10 ppm or less, preferably 5 ppm or less.

[0096] According to one embodiment of the present application, the dehydration method further includes a step of measuring the content of C2 unsaturated impurities in the product. The content can be measured, for example, by an infrared spectroscopic analyzer. Typically, the measurement is performed at the reaction product outlet of the dehydration reactor. The content measurement can be performed continuously, intermittently, online, or offline, and is not particularly limited.

[0097] According to this embodiment of the present application, the content is measured to obtain a content measurement (unit: ppm). The content measurement is then compared with a preset content value, such as 50 ppm, 30 ppm, 25 ppm, or 22 ppm (based on 100% by mass of the total mass of the product). The preset value represents a maximum level of C2 unsaturated impurities (typically ethylene + acetylene) in the reaction product that is acceptable to those skilled in the art, such as 20 ppm ethylene or 2 ppm acetylene.

[0098] According to this embodiment of the present application, when the measured content value is greater than a preset value (trigger condition) by the comparison, the conversion rate of isopropanol is measured to obtain a measured conversion rate value (set as D, unit %). Typically, the conversion rate measurement is performed at the reaction product outlet of the dehydration reactor. The conversion rate measurement can be performed continuously, intermittently, online, or offline, and is not particularly limited. Furthermore, according to the present application, the content measurement and the conversion rate measurement can be performed simultaneously or sequentially in a certain order, and are not particularly limited. However, from the viewpoint of efficiency, the conversion rate measurement is usually performed when the trigger condition is satisfied.

[0099] According to this embodiment of the present application, if the measured value D is between 96.0% and 99.0%, the water content of the starting material is increased, provided that the increased water content is in the range of 0.1 to 5.0% by mass (based on 100% by mass of the total mass of the starting material), where the magnitude (amplitude) of the increase is typically 0.01 to 50 times, 0.01 to 20 times, 0.01 to 10 times, 0.01 to 5 times, 0.01 to 1 time, 0.01 to 0.5 times, 0.01 to 0.3 times, 0.01 to 0.2 times, or 0.01 to 0.1 times. According to the present application, preferably, when a plane Cartesian coordinate system is established with the abscissa representing the isopropanol conversion rate (unit: %) (starting point: 96.0, end point: 99.0) and the ordinate representing the water content (unit: %) of the starting material (starting point: 0.1, end point: 5.0), with coordinate (0,0) as the origin, a straight line segment is drawn from coordinate (96.0,0.1) to coordinate (99.0,5.0), and the coordinate of measured value D on the straight line segment is set as (D, B1), where B1 represents the water content value corresponding to measured value D on the straight line segment. The increased water content value is selected to be a value in the range of B1 to 5.0, preferably a value in the range of B1 to B1 + (5.0 - B1) / 2. The increased water content value is typically selected to be B1 or its vicinity. According to the present invention, when the conversion rate of isopropanol is changed by changing the reaction temperature (for example, by increasing the reaction temperature), this control method can control the content of ethylene impurities in the reaction product to 20 ppm or less, and the content of acetylene in the reaction product to 2 ppm or less.

[0100] According to this embodiment of the present application, if the measured value D is between 99.0% and 99.9%, the water content of the starting material is increased, provided that the water content after the increase is in the range of 5.0 to 10.0% by mass (preferably 5.0 to 9.0% by mass) (based on 100% by mass of the total mass of the starting material), where the magnitude (amplitude) of the increase is typically 0.01 to 3 times, 0.01 to 2 times, 0.01 to 1 time, 0.01 to 0.5 times, 0.01 to 0.3 times, 0.01 to 0.2 times, or 0.01 to 0.1 times. According to the present application, preferably, when a plane Cartesian coordinate system is established with the abscissa representing the conversion rate of isopropanol (unit: %) (starting point: 99.0, end point: 99.9), the ordinate representing the water content of the starting material (unit: %) (starting point: 5.0, end point: 10.0), and the origin being coordinate (0,0), a straight line section (line segment) is drawn from coordinate (99.0,5.0) to coordinate (99.9,10.0), and the coordinate of the measured value D on the straight line section is set as (D, B2), where B2 represents the water content value corresponding to the measured value D on the straight line section, a value in the range of B2 to 10.0 (preferably B2 to 9.0) is selected as the increased water content value, and preferably a value in the range of B2 to B2 + (10.0 - B2) / 2 (preferably B2 to B2 + (9.0 - B2) / 2) is selected as the increased water content value. The value of the water content after the increase is typically selected to be at or near B2. According to the present application, when the conversion rate of isopropanol is changed by changing the reaction temperature (e.g., by increasing the reaction temperature), this control method can control the content of ethylene impurities in the reaction product to 20 ppm or less, and the content of acetylene in the reaction product to 2 ppm or less.

[0101] According to one embodiment of the present application, the present invention also relates to a method for producing propylene, the method comprising: subjecting acetone as a starting material to a hydrogenation reaction in the presence of a hydrogenation catalyst to produce a product containing isopropanol; separating the isopropanol-containing product to obtain a hydrogen-containing gas and an isopropanol-containing liquid; Separating the isopropanol-containing liquid to obtain isopropanol; a step of subjecting isopropanol to a dehydration reaction to produce a propylene-containing product by the dehydration method of any of the above embodiments (referred to as a dehydration step); washing the propylene-containing product with an absorbent to obtain a crude propylene product and a concentrated absorbent; separating the concentrated absorbent to obtain an isopropanol / water azeotrope; separating and removing heavy components from the crude propylene product to obtain purified propylene; Includes:

[0102] According to one embodiment of the present application, acetone hydrogenation can be carried out by any method known in the art. For example, acetone hydrogenation can be carried out in the presence of an acetone hydrogenation catalyst. Any catalyst capable of hydrogenating acetone to isopropanol can be used. However, nickel-based or copper-based catalysts are typically used in terms of production cost, applicability, etc., where the nickel content of the nickel-based catalyst is typically 5-45 mass% and may also contain other active or auxiliary components. The copper content of the copper-based catalyst is typically 8-45 mass% and may also contain other active or auxiliary components. More preferably, in the method for producing isopropanol by acetone hydrogenation, the copper-based catalyst has good hydrogenation activity and selectivity under very mild conditions, resulting in low energy and material consumption throughout the entire system. Furthermore, in acetone hydrogenation, the reaction temperature is typically 100-200°C, the reaction pressure is 0.5-6.0 MPaG, and the volumetric space velocity of the catalyst is 0.05-15 h . -1 The molar ratio of hydrogen to acetone is 2:1 to 15:1.

[0103] According to the present invention, the isopropanol-containing product is separated to obtain a hydrogen-containing gas and an isopropanol-containing liquid. Here, the gas can be recycled, and the liquid, which contains a small amount of unreacted acetone and heavy component by-products, is sent to a fractionation column for impurity removal to obtain purified isopropanol. According to the present invention, there are no limitations on the separation and removal, and knowledge known in the art can be applied as is.

[0104] According to one embodiment of the present application, the method further comprises recycling at least a portion of the isopropanol / water azeotrope to the dehydration step, where at least a portion is preferably at least 50 wt%, at least 80 wt%, at least 90 wt%, or substantially 100 wt% (i.e., substantially all recycled).

[0105] According to one embodiment of the present application, the present invention further relates to an apparatus for producing propylene, comprising, in series, an acetone hydrogenation reactor, a hydrogenation product gas-liquid separator, a fractionation column, an isopropanol dehydration reactor, a propylene absorption and separation column, an azeotropic distillation column, and a crude propylene heavy fractionation column, wherein the propylene apparatus is an apparatus specifically used for carrying out the above-mentioned propylene production method of the present application.

[0106] According to one embodiment of the present application, in an apparatus for producing propylene, the acetone hydrogenation reactor is configured to hydrogenate acetone as a starting material in the presence of a hydrogenation catalyst to produce an isopropanol-containing product; the hydrogenation product gas-liquid separator is configured to separate the isopropanol-containing product to obtain a hydrogen-containing gas and an isopropanol-containing liquid; the fractionation column is configured to separate the isopropanol-containing liquid to obtain isopropanol; the isopropanol dehydration reactor is configured to dehydrate isopropanol as a starting material in the presence of an alumina-containing dehydration catalyst to produce a propylene-containing product; the propylene absorption separation column is configured to wash the propylene-containing product with an absorbent to obtain a crude propylene product and a strong absorbent; the azeotropic distillation column is configured to separate the strong absorption liquid to obtain an isopropanol / water azeotrope; The crude propylene heavy fractionator is configured to separate and remove heavy components from the crude propylene product to obtain purified propylene. According to the present application, there is no need to provide a column for removing light components to obtain purified propylene.

[0107] According to one embodiment of the present application, in the apparatus for producing propylene, the upper end and / or upper material outlet of the azeotropic distillation column is connected to the material inlet of the isopropanol dehydration reactor. This specific communication structure makes it possible to recycle at least a portion of the isopropanol / water azeotropic mixture to the dehydration step.

[0108] According to one embodiment of the present application, in an apparatus for producing propylene, the bottom liquid outlet of the azeotropic distillation column is in communication with the absorbent inlet of the propylene absorption separation column.

[0109] According to one embodiment of the present application, the acetone hydrogenation reactor is a fixed-bed reactor, preferably a tubular fixed-bed reactor, and since the acetone hydrogenation reaction has a strong heat release, a catalyst is packed inside the tube, and a heat removal medium is introduced outside the tube.

[0110] According to one embodiment of the present application, the isopropanol dehydration reactor is a fixed-bed reactor, preferably a tubular fixed-bed reactor. Since the dehydration of isopropanol is an endothermic reaction, a catalyst is packed inside the tubes, and a heat supply medium is introduced outside the tubes.

[0111] According to one embodiment of the present application, in an apparatus for producing propylene, at least two measuring devices, at least one comparator, and at least one controller are provided at a product outlet of an isopropanol dehydration reactor. Of the at least two measuring devices, at least one is configured to measure the C3-C4 unsaturated impurity content and / or the C2 unsaturated impurity content of the product to obtain a measured content value, and at least one is configured to measure the isopropanol conversion rate to obtain a measured conversion rate value (such as the above-mentioned measured value C or measured value D). In addition, the at least one comparator is configured to compare the measured content value with a preset value and, preferably, based on the comparison result (e.g., the measured content value is greater than the preset value) and the measured conversion rate, issue a command to the controller to implement the impurity control scheme described above. The command typically increases the water content of the starting material for the isopropanol dehydration reactor in accordance with the impurity control scheme. The controller is also configured to execute a command to substantially increase the water content of the starting material for the isopropanol dehydration reactor. For example, a controller may be provided on the azeotrope circulation line to increase the azeotrope circulation ratio, or on the water make-up line to increase the amount of make-up water to the starting material.

[0112] Without being bound by any theory, the present inventors believe that in the dehydration reaction of isopropanol, when the dehydration catalyst contains alumina, the dimerization of propylene into propylene dimers such as 4-methyl-1-pentene and the cleavage of the dimer into C2 and C4 olefins and alkyne components are promoted by the presence of B acid sites on the dehydration catalyst. By including a small amount of water (e.g., greater than 0.1% by weight) in the starting material as a nucleophilic competitor for the B acid sites, the present invention can achieve competition between two side reactions: propylene dimerization and decomposition of the dimerized product, thereby inhibiting the occurrence of side reactions while maintaining reaction efficiency. However, if the water content is too high (e.g., greater than 10.0% by weight), the dehydration catalyst becomes susceptible to hydrolysis and other reactions, and the increased number of B acid sites may worsen side reactions. In addition, the present application identifies the relationship between the water content and the heavy and light components after the reaction, thereby facilitating predictable operation during the reaction process, avoiding the influence of blind operation on the production of impurities, and at the same time, realizing effective inhibition of the impurity content under conditions that can provide a high conversion rate of isopropanol. [Example]

[0113] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. [Example]

[0114] This example provides a process system for producing propylene from acetone: As shown in FIG. 1 , the treatment system includes an acetone starting material storage tank, an acetone hydrogenation reactor, a gas-liquid separator, a fractionating column, an isopropanol storage tank, an isopropanol dehydration reactor, an absorption separation column, a compressor, and a crude propylene purification column, which are connected in series. In this case, the outlet at the top of the absorption separation column is connected to the compressor, the outlet at the bottom of the absorption separation column is connected to the azeotropic distillation column, the azeotropic outlet of the azeotropic distillation column is connected to the inlet of the isopropanol dehydration reactor, and the outlet at the bottom of the azeotropic distillation column is connected to the inlet of the absorption separation column in parallel with the absorbent entering the absorption separation column. The gas outlet of the gas-liquid separator is connected to the compressor and finally to the acetone hydrogenation reactor. The hydrogen obtained by gas-liquid separation is used as make-up hydrogen for acetone hydrogenation. The light component product outlet at the top of the fractionating column is connected to the acetone starting material storage tank, and incompletely reacted acetone is recycled.

[0115] The acetone hydrogenation reactor is a tubular reactor, the inside of which is filled with an acetone hydrogenation catalyst, and a heat removal medium is introduced outside the tube to remove the reaction heat in a timed manner.The isopropanol dehydration reactor is a tubular reactor, the inside of which is filled with an isopropanol dehydration catalyst, and a heat supply medium is introduced outside the tube to supply heat.

[0116] The process for producing propylene from acetone using the above processing system is divided into an acetone hydrogenation section and an isopropanol dehydration section.

[0117] Acetone hydrogenation section: The acetone starting material is passed through an acetone starting material storage tank, its pressure is increased, and the acetone starting material is mixed with circulating hydrogen to heat it. The mixture is then fed to an acetone hydrogenation reactor for hydrogenation in the presence of an acetone hydrogenation catalyst, resulting in a reaction effluent containing isopropanol. The reaction effluent is condensed, cooled, and then sent to a gas-liquid separator. The separated gas is compressed by a compressor and then recycled, and the separated liquid is sent to a fractionation column. The isopropanol-containing mixture is fractionated in the fractionation column to remove small amounts of light and heavy components to obtain purified isopropanol. The removed light components, typically unreacted acetone, are recycled to the starting material tank, and the removed heavy components, typically acetone hydrogenation by-products, can be discharged continuously or intermittently.

[0118] Isopropanol dehydration section: The purified isopropanol obtained from the acetone hydrogenation section is used as a starting material and passed through an isopropanol storage tank, mixed with the azeotropic distillation product obtained in the azeotropic distillation column and / or additional water, and sent to an isopropanol dehydration reactor for isopropanol dehydration in the presence of a dehydration catalyst to obtain a reaction effluent containing propylene. The reaction effluent is passed through the bottom of an absorption separation column, an absorbent is introduced into the top of the absorption separation column, and after heat exchange and absorption mass transfer exchange within the column, crude propylene is discharged from the top of the column and compressed by a compressor. A rich absorption liquid is discharged from the bottom of the column and passed through an azeotropic distillation column. After being compressed by the compressor, the crude propylene is sent to a crude propylene purification column to separate purified propylene and a small amount of heavy components, where the heavy components are typically propylene polymers and are intermittently discharged. The concentrated absorption liquid sent to the azeotropic distillation column is azeotropically distilled in the column to obtain an azeotropic mixture at the top of the column, and the bottom product of the column is recycled to the absorption separation column as an absorbent for reuse.

[0119] The acetone starting material used in the following examples and comparative examples was available from the equipment, the specifications of which are shown in Table 1.

[0120] [Table 2]

[0121] Propylene was produced from acetone using the system and method described above as follows.

[0122] Propylene was prepared from the acetone starting material described above: The acetone hydrogenation reactor tube size was φ20 × 2.0 mm and the tube length was 1.5 m. A heat removal medium, water, was introduced outside the reactor tube, and the water was vaporized to remove heat and generate steam at 0.3 MPa. The acetone hydrogenation conditions were a temperature of 170 °C, a pressure of 3.5 MPa, and a catalyst space velocity of 1.5 h -1 The mixture contained a hydrogen / acetone volume ratio of 10:1. The acetone hydrogenation catalyst was a copper-based catalyst developed by Sinopec (Dalian) Research Institute of Petroleum and Petrochemicals Co. Ltd. and had a cylindrical shape.

[0123] Isopropanol was prepared by hydrogenation of acetone, and the isopropanol starting material was mixed with the fractionated distillation product and water obtained at the top of the azeotropic column and then subjected to dehydration.

[0124] The size of the isopropanol dehydration reactor tube is φ10 × 2.0, and the conditions for isopropanol dehydration are temperature 280 °C, pressure 0.3 MPa, and catalyst space velocity 1.5 h -1 and an isopropanol dehydration catalyst, a self-made alumina-based catalyst prepared as follows: amorphous silica-alumina pellets with an alumina content of 10% by mass were treated in a saturated steam atmosphere at a temperature of 450°C for 10 hours to obtain the isopropanol dehydration catalyst. The catalyst was spherical.

[0125] In the isopropanol dehydration section, the water content of the isopropanol starting material was 8% by mass, the isopropanol content in the product was 3.2% by mass, the content of C2 unsaturated impurities in the reaction effluent was 9 ppm, the content of C3-C4 unsaturated impurities in the reaction effluent was 3 ppm, and the conversion of isopropanol was 96.8%.

[0126] The properties of the final propylene product, the selectivity of the isopropanol dehydration catalyst, the composition of unsaturated hydrocarbon impurities in the product, and the energy consumption (energy consumption refers to the energy consumption per ton of product of the entire process when the qualified propylene product is produced by the dehydration of isopropanol) are shown in Table 2. [Example]

[0127] Isopropanol was prepared using the starting materials and methods described in Example 1, and isopropanol and water were mixed directly and then used as the starting material for dehydration.

[0128] The size of the isopropanol dehydration reactor tube is φ10 × 2.0, and the conditions for isopropanol dehydration are temperature 280 °C, pressure 0.3 MPa, and catalyst space velocity 1.5 h -1 and an isopropanol dehydration catalyst, a self-made alumina-based catalyst prepared as follows: amorphous silica-alumina pellets with an alumina content of 10% by mass were treated in a saturated steam atmosphere at a temperature of 450°C for 10 hours to obtain the isopropanol dehydration catalyst. The catalyst was spherical.

[0129] In the isopropanol dehydration section, the water content of the isopropanol starting material was 0.5% by mass, the isopropanol content in the product was 2.0% by mass, the content of C2 unsaturated impurities in the reaction effluent was 40 ppm, the content of C3-C4 unsaturated impurities in the reaction effluent was 18 ppm, and the conversion of isopropanol was 98.0%.

[0130] The properties of the final propylene product, the selectivity of the isopropanol dehydration catalyst, the composition of unsaturated hydrocarbon impurities in the product, and the energy consumption (energy consumption refers to the energy consumption per ton of product of the entire process when the qualified propylene product is produced by the dehydration of isopropanol) are shown in Table 2. [Example]

[0131] Isopropanol was prepared using the starting materials and methods described in Example 1, and isopropanol and water were mixed directly and then used as the starting material for dehydration.

[0132] The size of the isopropanol dehydration reactor tube is φ10 × 2.0, and the conditions for isopropanol dehydration are temperature 280 °C, pressure 0.3 MPa, and catalyst space velocity 1.5 h -1 and an isopropanol dehydration catalyst, a self-made alumina-based catalyst prepared as follows: amorphous silica-alumina pellets with an alumina content of 10% by mass were treated in a saturated steam atmosphere at a temperature of 450°C for 10 hours to obtain the isopropanol dehydration catalyst. The catalyst was spherical.

[0133] In the isopropanol dehydration section, the water content of the isopropanol starting material was 2% by mass, the isopropanol content in the product was 2.3% by mass, the content of C2 unsaturated impurities in the reaction effluent was 21 ppm, the content of C3-C4 unsaturated impurities in the reaction effluent was 9 ppm, and the conversion of isopropanol was 97.7%.

[0134] The properties of the final propylene product, the selectivity of the isopropanol dehydration catalyst, the composition of unsaturated hydrocarbon impurities in the product, and the energy consumption (energy consumption refers to the energy consumption per ton of product of the entire process when the qualified propylene product is produced by the dehydration of isopropanol) are shown in Table 2. [Example]

[0135] Isopropanol was produced using the starting materials and method described in Example 1, and isopropanol and water were directly mixed and then used as the starting material for dehydration, and the isopropanol in the product was purified by extractive rectification and reused.

[0136] The size of the isopropanol dehydration reactor tube is φ10 × 2.0, and the conditions for isopropanol dehydration are temperature 280 °C, pressure 0.3 MPa, and catalyst space velocity 1.5 h -1 and an isopropanol dehydration catalyst, a self-made alumina-based catalyst prepared as follows: amorphous silica-alumina pellets with an alumina content of 10% by mass were treated in a saturated steam atmosphere at a temperature of 450°C for 10 hours to obtain the isopropanol dehydration catalyst. The catalyst was spherical.

[0137] In the isopropanol dehydration section, the water content of the isopropanol starting material was 8 mass%, the isopropanol content in the product was 3.1 mass%, the content of C2 unsaturated impurities in the reaction effluent was 4 ppm, the content of C3-C4 unsaturated impurities in the reaction effluent was 3 ppm, and the conversion of isopropanol was 96.9%.

[0138] The properties of the final propylene product, the selectivity of the isopropanol dehydration catalyst, the composition of unsaturated hydrocarbon impurities in the product, and the energy consumption (energy consumption refers to the energy consumption per ton of product of the entire process when the qualified propylene product is produced by the dehydration of isopropanol) are shown in Table 2. [Example]

[0139] Isopropanol was prepared using the starting materials and methods described in Example 1, and isopropanol and water were mixed directly and then used as the starting material for dehydration.

[0140] The size of the isopropanol dehydration reactor tube is φ10 × 2.0, and the conditions for isopropanol dehydration are temperature 280 °C, pressure 0.3 MPa, and catalyst space velocity 1.5 h -1The catalyst contained a self-prepared molecular sieve catalyst, an isopropanol dehydration catalyst, and a cloverleaf-shaped catalyst.

[0141] In the isopropanol dehydration section, the water content of the isopropanol starting material was 8% by mass, the isopropanol content in the product was 2.8% by mass, the content of C2 unsaturated impurities in the reaction effluent was 10 ppm, the content of C3-C4 unsaturated impurities in the reaction effluent was 5 ppm, and the conversion of isopropanol was 97.2%.

[0142] The properties of the final propylene product, the selectivity of the isopropanol dehydration catalyst, the composition of unsaturated hydrocarbon impurities in the product, and the energy consumption (energy consumption refers to the energy consumption per ton of product of the entire process when the qualified propylene product is produced by the dehydration of isopropanol) are shown in Table 2. [Example]

[0143] Isopropanol was prepared using the starting materials and methods described in Example 1, and isopropanol and water were mixed directly and then used as the starting material for dehydration.

[0144] The size of the isopropanol dehydration reactor tube is φ10 × 2.0, and the conditions for isopropanol dehydration are temperature 280 °C, pressure 0.3 MPa, and catalyst space velocity 1.5 h -1 The starting material for isopropanol contained a water content of 1%, and the isopropanol dehydration catalyst was a self-made alumina-based catalyst prepared as follows: amorphous silica-alumina pellets with an alumina content of 10% by mass were treated in a saturated water vapor atmosphere at a temperature of 450°C for 10 hours to obtain the isopropanol dehydration catalyst. The catalyst was spherical.

[0145] During operation of the apparatus, the reaction temperature was increased to maintain or increase the reaction conversion rate and improve reaction efficiency. The reaction temperature was increased to 290 ° C, and measurements were carried out. The measurements showed that the methylacetylene and propadiene contents in the gas product were 6 ppm, the butylene and butadiene contents in the gas product were 7 ppm, the isopropanol content in the product was 2.5 mass%, and the conversion rate was 97.5%. After calculating according to the formula for adjusting the moisture content of the reconstituted material described in this application, the moisture content of the isopropanol in the starting material was adjusted to 1.5%, and measurements carried out under these reaction conditions showed that the C2 unsaturated impurities content in the reaction effluent was 15 ppm, the methylacetylene and propadiene contents were 5 ppm, and the butylene and butadiene contents were 4 ppm.

[0146] The properties of the final propylene product, the selectivity of the isopropanol dehydration catalyst, the composition of unsaturated hydrocarbon impurities in the product, and the energy consumption (energy consumption refers to the energy consumption per ton of product of the entire process when the qualified propylene product is produced by the dehydration of isopropanol) are shown in Table 2. [Example]

[0147] Isopropanol was prepared using the starting materials and methods described in Example 1, and isopropanol and water were mixed directly and then used as the starting material for dehydration.

[0148] The size of the isopropanol dehydration reactor tube is φ10 × 2.0, and the conditions for isopropanol dehydration are temperature 290 °C, pressure 0.3 MPa, and catalyst space velocity 1.5 h -1 The starting material for isopropanol contained a water content of 1%, and the isopropanol dehydration catalyst was a self-made alumina-based catalyst prepared as follows: amorphous silica-alumina pellets with an alumina content of 10% by mass were treated in a saturated water vapor atmosphere at a temperature of 450°C for 10 hours to obtain the isopropanol dehydration catalyst. The catalyst was spherical.

[0149] During operation of the apparatus, the reaction temperature was increased to maintain or increase the reaction conversion rate and improve reaction efficiency. The reaction temperature was increased to 290°C, and measurements were conducted. The measurements showed that the ethylene content in the gas product was 23 ppm, the acetylene content in the gas product was 2 ppm, the isopropanol content in the product was 2.5 mass%, and the conversion rate was 97.5%. After calculating according to the formula for adjusting the water content described in this application, the water content of the isopropanol in the starting material was adjusted to 2.5%. Measurements conducted under these reaction conditions showed that the ethylene content in the reaction effluent was 14 ppm, the acetylene content was 1 ppm, the methylacetylene and propadiene contents were 4 ppm, and the butene and butadiene contents were 4 ppm.

[0150] The properties of the final propylene product, the selectivity of the isopropanol dehydration catalyst, the composition of unsaturated hydrocarbon impurities in the product, and the energy consumption (energy consumption refers to the energy consumption per ton of product of the entire process when the qualified propylene product is produced by the dehydration of isopropanol) are shown in Table 2. [Example]

[0151] Isopropanol was prepared using the starting materials and methods described in Example 1, and isopropanol and water were mixed directly and then used as the starting material for dehydration.

[0152] The size of the isopropanol dehydration reactor tube is φ10 × 2.0, and the conditions for isopropanol dehydration are temperature 280 °C, water content of the isopropanol starting material 3.5%, pressure 0.3 MPa, and space velocity of the catalyst 1.5 h -1 and an isopropanol dehydration catalyst, a self-made alumina-based catalyst prepared as follows: amorphous silica-alumina pellets with an alumina content of 10% by mass were treated in a saturated steam atmosphere at a temperature of 450°C for 10 hours to obtain the isopropanol dehydration catalyst. The catalyst was spherical.

[0153] During operation of the device, the reaction temperature was increased to maintain or increase the reaction conversion rate and improve reaction efficiency. The reaction temperature was increased to 301 ° C, and measurements were carried out. The measurements showed that the methylacetylene and propadiene contents in the gas product were 7 ppm, the butylene and butadiene contents in the gas product were 8 ppm, the isopropanol content in the product was 0.7 mass%, and the conversion rate was 99.3%. After calculating according to the formula for adjusting the moisture content of the reconstituted material described in this application, the moisture content of the isopropanol in the starting material was adjusted to 4.2%, and measurements carried out under these reaction conditions showed that the C2 unsaturated impurities content in the reaction effluent was 16 ppm, the methylacetylene and propadiene contents were 4 ppm, and the butylene and butadiene contents were 5 ppm.

[0154] The properties of the final propylene product, the selectivity of the isopropanol dehydration catalyst, the composition of unsaturated hydrocarbon impurities in the product, and the energy consumption (energy consumption refers to the energy consumption per ton of product of the entire process when the qualified propylene product is produced by the dehydration of isopropanol) are shown in Table 2. [Example]

[0155] Isopropanol was prepared using the starting materials and methods described in Example 1, and isopropanol and water were mixed directly and then used as the starting material for dehydration.

[0156] The size of the isopropanol dehydration reactor tube is φ10 × 2.0, and the conditions for isopropanol dehydration are temperature 280 °C, water content of the isopropanol starting material 3.5%, pressure 0.3 MPa, and space velocity of the catalyst 1.5 h -1 and an isopropanol dehydration catalyst, a self-made alumina-based catalyst prepared as follows: amorphous silica-alumina pellets with an alumina content of 10% by mass were treated in a saturated steam atmosphere at a temperature of 450°C for 10 hours to obtain the isopropanol dehydration catalyst. The catalyst was spherical.

[0157] During operation of the apparatus, the reaction temperature was increased to maintain or increase the reaction conversion rate and improve reaction efficiency. The reaction temperature was increased to 301°C, and measurements were conducted. The measurements showed that the ethylene content in the gas product was 22 ppm, the acetylene content in the gas product was 2 ppm, and the isopropanol content in the product was 0.7 mass%, with a conversion rate of 99.3%. After calculating according to the formula for adjusting the water content described in this application, the water content of the isopropanol in the starting material was adjusted to 6.6%. Measurements conducted under these reaction conditions showed that the ethylene content in the reaction effluent was 18 ppm, the acetylene content was 1 ppm, the methylacetylene and propadiene contents were 4 ppm, and the butene and butadiene contents were 4 ppm.

[0158] The properties of the final propylene product, the selectivity of the isopropanol dehydration catalyst, the composition of unsaturated hydrocarbon impurities in the product, and the energy consumption (energy consumption refers to the energy consumption per ton of product of the entire process when the qualified propylene product is produced by the dehydration of isopropanol) are shown in Table 2. [Example]

[0159] Isopropanol was prepared using the starting materials and methods described in Example 1, and isopropanol and water were mixed directly and then used as the starting material for dehydration.

[0160] The size of the isopropanol dehydration reactor tube is φ10 × 2.0, and the conditions for isopropanol dehydration are temperature 280 °C, water content of the isopropanol starting material 7.0%, pressure 0.2 MPa, and space velocity of the catalyst 1.5 h -1 and an isopropanol dehydration catalyst, a self-made alumina-based catalyst prepared as follows: amorphous silica-alumina pellets with an alumina content of 10% by mass were treated in a saturated steam atmosphere at a temperature of 450°C for 10 hours to obtain the isopropanol dehydration catalyst. The catalyst was spherical.

[0161] During operation of the apparatus, the reaction temperature was increased to maintain or increase the reaction conversion rate and improve reaction efficiency. The reaction temperature was increased to 308 ° C, and measurements were conducted. The measurements showed that the methylacetylene and propadiene contents in the gas product were 7 ppm, the butylene and butadiene contents in the gas product were 6 ppm, the isopropanol content in the product was 0.3 mass%, and the conversion rate was 99.7%. After calculating according to the formula for adjusting the moisture content of the reconstituted material described in this application, the moisture content of the isopropanol in the starting material was adjusted to 8.7%. Measurements conducted under these reaction conditions showed that the C2 unsaturated impurities content in the reaction effluent was 21 ppm, the methylacetylene and propadiene contents were 3 ppm, and the butylene and butadiene contents were 5 ppm.

[0162] The properties of the final propylene product, the selectivity of the isopropanol dehydration catalyst, the composition of unsaturated hydrocarbon impurities in the product, and the energy consumption (energy consumption refers to the energy consumption per ton of product of the entire process when the qualified propylene product is produced by the dehydration of isopropanol) are shown in Table 2. Comparative Example 1

[0163] Pure isopropanol was used as the starting material and fed into the reactor for dehydration, and the tube size of the isopropanol dehydration reactor was φ10×2.0.

[0164] The conditions for isopropanol dehydration were a temperature of 280°C, a pressure of 0.3 MPa, and a space velocity of 1.5 h -1 and an isopropanol dehydration catalyst, a homemade alumina-based catalyst prepared as follows: amorphous silica-alumina pellets with an alumina content of 10% by mass were treated in a saturated steam atmosphere at a temperature of 450°C for 10 hours to obtain an isopropanol dehydration catalyst. The catalyst was spherical, and the product was analyzed by gas chromatography.

[0165] Here, the water content of the isopropanol starting material was 0% by mass, and the isopropanol content in the product was 0.9% by mass.

[0166] The properties of the final propylene product, the conversion of isopropanol, the composition of alkene and alkyne impurities in the product, and the energy consumption (energy consumption refers to the energy consumption per ton of product of the entire process when the qualified propylene product is produced by dehydration of isopropanol) are shown in Table 2. Comparative Example 2

[0167] Pure isopropanol was used as the starting material and fed into the reactor for dehydration, and the tube size of the isopropanol dehydration reactor was φ10×2.0.

[0168] The conditions for isopropanol dehydration were a temperature of 300°C, a pressure of 0.3 MPa, and a space velocity of 1.5 h -1 and an isopropanol dehydration catalyst, a homemade alumina-based catalyst prepared as follows: amorphous silica-alumina pellets with an alumina content of 10% by mass were treated in a saturated steam atmosphere at a temperature of 450°C for 10 hours to obtain an isopropanol dehydration catalyst. The catalyst was spherical, and the product was analyzed by gas chromatography.

[0169] Here, the water content of the isopropanol starting material was 0% by mass, and the isopropanol content of the product was 0.3% by mass.

[0170] The properties of the final propylene product, the conversion of isopropanol, the composition of alkene and alkyne impurities in the product, and the energy consumption (energy consumption refers to the energy consumption per ton of product of the entire process when the qualified propylene product is produced by dehydration of isopropanol) are shown in Table 2. Comparative Example 3

[0171] Pure isopropanol was used as the starting material and fed into the reactor for dehydration, and the tube size of the isopropanol dehydration reactor was φ10×2.0.

[0172] The conditions for isopropanol dehydration were a temperature of 330°C, a pressure of 0.3 MPa, and a space velocity of 1.5 h -1 and an isopropanol dehydration catalyst, a homemade alumina-based catalyst prepared as follows: amorphous silica-alumina pellets with an alumina content of 10% by mass were treated in a saturated steam atmosphere at a temperature of 450°C for 10 hours to obtain an isopropanol dehydration catalyst. The catalyst was spherical, and the product was analyzed by gas chromatography.

[0173] Here, the water content of the isopropanol starting material was 16% by mass, and the isopropanol content of the product was 0.5% by mass.

[0174] The properties of the final propylene product, the conversion of isopropanol, the composition of alkene and alkyne impurities in the product, and the energy consumption (energy consumption refers to the energy consumption per ton of product of the entire process when the qualified propylene product is produced by dehydration of isopropanol) are shown in Table 2. Comparative Example 4

[0175] Pure isopropanol was used as the starting material and fed into the reactor for dehydration, and the tube size of the isopropanol dehydration reactor was φ10×2.0.

[0176] The conditions for dehydration of isopropanol were: temperature 300°C, pressure 0.3 MPa, space velocity of catalyst 1.5 h -1 The product was analyzed by gas chromatography.

[0177] Here, the water content of the isopropanol starting material was 3.0% by mass, and the isopropanol content of the product was 0.2% by mass.

[0178] The properties of the final propylene product, the conversion of isopropanol, the composition of alkene and alkyne impurities in the product, and the energy consumption (energy consumption refers to the energy consumption per ton of product of the entire process when the qualified propylene product is produced by dehydration of isopropanol) are shown in Table 2.

[0179] [Table 3]

Claims

1. A dehydration method comprising: a step referred to as a dehydration step in which an isopropanol-containing starting material is subjected to a dehydration reaction in the presence of a dehydration catalyst comprising alumina to produce a propylene-containing product; The starting material has a water content of 0.1 to 10.0% by weight, based on 100% by weight of the total weight of the starting material; the product has a total content of C2 unsaturated impurities and C3-C4 unsaturated impurities of 80 ppm or less, based on 100% by weight of the total weight of the product; The alumina-containing dehydration catalyst is an amorphous silica-alumina having an alumina content of 1 to 30% by mass, with the remainder being silica; The amorphous silica-alumina is subjected to a saturated steam treatment at 300 to 500°C; the product having a C2 unsaturated impurity content of 50 ppm or less; A dehydration method characterized in that the conversion rate of isopropanol is 96.0 to 99.9%.

2. The starting material has a water content of 3.0 to 5.0% by mass, relative to 100% by mass of the total mass of the starting material, and / or 2. The dehydration method of claim 1, wherein the product has a total content of C2 unsaturated impurities and C3-C4 unsaturated impurities of 30 ppm or less, based on 100% by weight of the total weight of the product.

3. The product is a C2 unsaturated impurity content of 30 ppm or less, based on 100% by weight of the total weight of the product, and / or a C3-C4 unsaturated impurity content of 30 ppm or less, based on 100% by weight of the total weight of the product; and / or a propylene content of 65.0 to 69.8% by weight, based on 100% by weight of the total weight of the product; The dehydration method according to claim 1, characterized in that it comprises:

4. The product a C2 unsaturated impurity content of 22 ppm or less, based on 100% by weight of the total weight of the product, and / or a C3-C4 unsaturated impurity content of 5 ppm or less, based on 100% by weight of the total weight of the product, and / or a propylene content of 66.0 to 69.5% by weight, based on 100% by weight of the total weight of the product; The dehydration method according to claim 3, characterized in that it comprises:

5. the starting material has an isopropanol content of 90.0 to 99.9% by weight, based on 100% by weight of the total weight of the starting material; and / or 2. The dehydration method according to claim 1, wherein the conversion rate of isopropanol is 97.0 to 99.8%.

6. The starting material has an isopropanol content of 92.0 to 97.0% by mass, relative to 100% by mass of the total mass of the starting material, and / or The dehydration method according to claim 5, wherein the conversion rate of isopropanol is 98.5 to 99.5%.

7. The amorphous silica-alumina is 2. The dehydration method according to claim 1, wherein the amorphous silica-alumina has an alumina content of 1 to 15% by mass, the remainder being silica.

8. 2. The dehydration method according to claim 1, wherein the operation conditions of the dehydration step are a reaction temperature of 150 to 450° C., a reaction pressure of 0.05 to 1.0 MPaG, and a volumetric space velocity of 0.05 to 5.0 h −1 .

9. The dehydration method according to claim 1, wherein the operation conditions of the dehydration step are a reaction temperature of 200 to 350° C., a reaction pressure of 0.1 to 0.5 MPaG, and a volumetric space velocity of 1 to 3 h −1 .

10. further comprising the step of separating the isopropanol / water mixture from the product; or Further, the following steps: (1) washing the product with an absorbent to obtain a crude propylene product and a concentrated absorbent; (2) subjecting the crude propylene product to separation to remove heavy components to obtain purified propylene; (3) subjecting the concentrated absorbent to separation to obtain an isopropanol / water mixture; The dehydration method according to claim 1, comprising:

11. The isopropanol / water mixture is an isopropanol / water azeotrope, and / or In step (1), the absorbent is at least one selected from the group consisting of water and isopropanol, and / or In step (2), the crude propylene product is subjected to separation to remove only heavy components, and / or 11. The dehydration method according to claim 10, wherein in step (3), the concentrated absorption liquid is subjected to separation to obtain an isopropanol / water azeotrope.

12. 11. The dehydration method according to claim 10, wherein the mixture has a water content of 5 to 90% by mass, relative to 100% by mass of the total mass of the mixture.

13. The dehydration method of claim 12, wherein the mixture has a water content of 12 to 13 mass % relative to 100 mass % of the total mass of the mixture.

14. 11. The dehydration method according to claim 10, further comprising a step referred to as a recycling step of recycling at least a portion of the mixture to the dehydration step.

15. The dehydration method of claim 14, wherein substantially 100% by mass of the mixture is recycled to the dehydration step.

16. 15. The dehydration method of claim 14, wherein in the recycling step, at least a portion of the mixture is mixed with the starting material of the dehydration step, optionally supplemented with an additional amount of water, to adjust the moisture content of the starting material to a predetermined level.

17. further comprising measuring the C3-C4 unsaturated impurity content of the product and comparing the measured content in ppm with a predetermined value; If the measured content is greater than the predetermined value, measuring the conversion of isopropanol to obtain a measured conversion in %, designated as C; （１） If the measured value C is between 96.0% and 99.0%, increasing the water content of the starting material by 0.01 to 30 times, provided that the water content after the increase is in the range of 0.1 to 3.0% by weight, relative to 100% by weight of the total weight of the starting material; （２） If the measured value C is between 99.0% and 99.5%, increasing the water content of the starting material by 0.01 to 2 times, provided that the water content after the increase is in the range of 3.0 to 5.0% by weight, based on 100% by weight of the total weight of the starting material; （３） If the measured value C is between 99.5% and 99.9%, the water content of the starting material is increased by 0.01 to 2 times, with the water content after the increase being selected to be a value in the range of 5.0 to 10.0% by mass relative to 100% by mass of the total mass of the starting material. The dehydration method according to claim 1 .

18. The predetermined value is 20 ppm based on 100% by weight of the total mass of the product, and / or In (1), if the measured value C is between 96.0% and 99.0%, increasing the water content of the starting material by 0.01 to 0.1 times, provided that the water content after the increase is in the range of 0.1 to 3.0% by mass relative to 100% by mass of the total mass of the starting material; and / or In (1), when a plane Cartesian coordinate system is established with the abscissa representing the conversion rate of isopropanol in % with a starting point of 96.0 and an end point of 99.0, the ordinate representing the water content of the starting material in % by mass with a starting point of 0.1 and an end point of 3.0, and the coordinate (0,0) representing the origin, a straight line section is drawn from the coordinate (96.0,0.1) to the coordinate (99.0,3.0), and the coordinate of the measured value C on the straight line section is set as (C, A1), where A1 represents the water content value corresponding to the measured value C on the straight line section. A value in the range of A1 to 3.0 is selected as the increased water content value; and / or In (2), if the measured value C is between 99.0% and 99.5%, increasing the water content of the starting material by 0.01 to 0.1 times, provided that the water content after the increase is in the range of 3.0 to 5.0% by mass relative to 100% by mass of the total mass of the starting material; and / or In (2), when a plane Cartesian coordinate system is established with the abscissa representing the conversion rate of isopropanol in % with a starting point of 99.0 and an end point of 99.5, the ordinate representing the water content of the starting material in % by mass with a starting point of 3.0 and an end point of 5.0, and the coordinate (0,0) representing the origin, a straight line section is drawn from the coordinate (99.0,3.0) to the coordinate (99.5,5.0), and the coordinate of the measured value C on the straight line section is set as (C,A2), where A2 represents the water content value corresponding to the measured value C on the straight line section. A value in the range of A2 to 5.0 is selected as the increased water content value; and / or In (3), if the measured value C is 99.5% to 99.9%, the water content of the starting material is increased by 0.01 to 0.1 times, provided that the water content after the increase is in the range of 5.0 to 10.0% by mass relative to 100% by mass of the total mass of the starting material; In (3), when a plane Cartesian coordinate system is established with the starting point being 99.5, the end point being 99.9, the value of the isopropanol conversion rate in units of % as the abscissa, the starting point being 5.0, the end point being 10.0, the value of the water content of the starting material in units of mass% as the ordinate, and the coordinate (0,0) as the origin, a straight line section is drawn from the coordinate (99.5,5.0) to the coordinate (99.9,10.0), and the coordinate of the measured value C on the straight line section is set as (C,A3), where A3 represents the water content value corresponding to the measured value C on the straight line section, and a value in the range of A3 to 9.0 is selected as the value of the water content after the increase; The dehydration method according to claim 17, 19. The predetermined value is 5 ppm based on 100% by weight of the total mass of the product, and / or In (1), a value in the range of A1 to A1 + (3.0 - A1) / 2 is selected as the value of the water content after the increase; In (2), a value in the range of A2 to A2 + (5.0 - A2) / 2 is selected as the value of the water content after the increase; In (3), the value of the water content after the increase is selected from the range of A3 to A3 + (9.0 - A3) / 2. The dehydration method according to claim 18,

20. further comprising the steps of measuring the C2 unsaturated impurity content of the product and comparing the measured content in ppm with a predetermined value, and if the measured content is greater than the predetermined value, measuring the conversion of isopropanol to obtain the measured conversion in %, designated as D; （１） If the measured value D is between 96.0% and 99.0%, increasing the water content of the starting material by 0.01 to 50 times, provided that the water content after the increase is in the range of 0.1 to 5.0% by weight, relative to 100% by weight of the total weight of the starting material; （２） 2. The dehydration method according to claim 1, wherein if the measured value D is between 99.0% and 99.9%, the water content of the starting material is increased by 0.01 to 3 times, with the increased water content being in the range of 5.0 to 10.0% by mass relative to 100% by mass of the total mass of the starting material.

21. The predetermined value is 50 ppm based on 100% by weight of the total mass of the product, and / or In (1), if the measured value D is between 96.0% and 99.0%, increasing the water content of the starting material by 0.01 to 0.1 times, provided that the water content after the increase is in the range of 0.1 to 5.0% by mass relative to 100% by mass of the total mass of the starting material; and / or In (1), when a plane Cartesian coordinate system is established with the abscissa representing the conversion rate of isopropanol in % with a starting point of 96.0 and an end point of 99.0, the ordinate representing the water content of the starting material in % by mass with a starting point of 0.1 and an end point of 5.0, and the coordinate (0,0) representing the origin, a straight line section is drawn from the coordinate (96.0,0.1) to the coordinate (99.0,5.0), and the coordinate of the measured value D on the straight line section is set as (D, B1), where B1 represents the water content value corresponding to the measured value D on the straight line section. A value in the range of B1 to 5.0 is selected as the increased water content value; and / or In (2), if the measured value D is between 99.0% and 99.9%, increasing the water content of the starting material by 0.01 to 0.1 times, provided that the water content after the increase is in the range of 5.0 to 9.0% by mass relative to 100% by mass of the total mass of the starting material; and / or In (2), the water content after the increase is in the range of 5.0 to 9.0% by mass relative to 100% by mass of the total mass of the starting material, and / or, when a plane Cartesian coordinate system is established with the starting point being 99.0 and the end point being 99.9, where the value of the isopropanol conversion rate in % is the abscissa, the starting point being 5.0 and the end point being 10.0, where the value of the water content of the starting material in % by mass is the ordinate, and the coordinate (0,0) is the origin, a straight line section is drawn from the coordinate (99.0,5.0) to the coordinate (99.9,10.0), and the coordinate of the measured value D on the straight line section is set as (D,B2), where B2 represents the value of the water content corresponding to the measured value D on the straight line section, and a value in the range of B2 to 9.0 is selected as the value of the water content after the increase; The dehydration method according to claim 20, 22. The predetermined value is 22 ppm relative to 100% by weight of the total mass of the product, and / or In (1), a value in the range of B1 to B1 + (5.0 - B1) / 2 is selected as the value of the water content after the increase; In (2), the value of the water content after the increase is selected to be a value in the range of B2 to B2 + (9.0 - B2) / 2. The dehydration method according to claim 21 .

23. A method for producing propylene, comprising: subjecting acetone as a starting material to a hydrogenation reaction in the presence of a hydrogenation catalyst to produce an isopropanol-containing product; separating the isopropanol-containing product to obtain a hydrogen-containing gas and an isopropanol-containing liquid; Separating the isopropanol-containing liquid to obtain isopropanol; a step referred to as a dehydration step, in which the isopropanol is dehydrated to produce a propylene-containing product by the dehydration method of claim 1; washing the propylene-containing product with an absorbent to obtain a crude propylene product and a concentrated absorbent; separating the concentrated absorption liquid to obtain an isopropanol / water azeotrope; separating and removing heavy components from the crude propylene product to obtain purified propylene; A method for producing propylene, comprising:

24. The method for producing propylene according to claim 23, further comprising a step of recycling 50 mass% or more of the isopropanol / water azeotrope to the dehydration step.

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