Method and device for preparing alcohol by liquid-phase hydrogenation of mixed aldehyde

Abstract

The invention relates to the technical field of petrochemical engineering, in particular to a method and a device for preparing alcohol through liquid-phase hydrogenation of mixed aldehyde. The method comprises the following steps: mixed aldehyde and hydrogen are subjected to a first liquid phase hydrogenation reaction, and an obtained first hydrogenation product is partially circulated to a raw material inlet of the first liquid phase hydrogenation reaction to be mixed with the mixed aldehyde and the hydrogen; and performing a second liquid phase hydrogenation reaction on the residual first hydrogenation product and hydrogen, partially circulating the obtained second hydrogenation product to a raw material inlet of the second liquid phase hydrogenation reaction to be mixed with the first hydrogenation product and the hydrogen, and discharging the residual second hydrogenation product as a crude alcohol product. According to the method, the mixed aldehyde is subjected to two-step liquid phase hydrogenation, and the liquid phase hydrogenation conditions are controlled in a segmented manner, so that the content of high-boiling residues in the product can be effectively reduced, the loss of the aldehyde is reduced, and the yield of the product alcohol is improved.

Description

Technical Field

[0001] The invention relates to the technical field of petrochemical engineering, and in particular to a method and a device for preparing alcohol by liquid-phase hydrogenation of mixed aldehydes. Background Art

[0002] In industrial production, due to product needs, mixed aldehydes often need to be hydrogenated together to prepare alcohols. For example, the process of propylene hydroformylation to produce butyl octanol involves the hydrogenation of butyraldehyde and octenal, and the process of mixed carbon tetrahydroformylation to produce pentanol / 2-propylheptanol involves the hydrogenation of valeraldehyde and decenal. Compared with hydrogenating the two aldehydes separately, sending the mixed aldehydes together to the hydrogenation reactor can save the amount of catalyst. Therefore, it is more economical to send the mixed aldehydes together to the hydrogenation reactor.

[0003] In the early days, the hydrogenation of butyraldehyde or octenaldehyde was usually carried out through a gas phase hydrogenation reactor. All aldehydes needed to be vaporized before entering the reactor, which consumed a lot of energy. At the same time, for aldehydes with more than 8 carbon atoms, the higher vaporization temperature would cause some aldehydes to polymerize to form high-boiling products. Therefore, in recent years, liquid phase hydrogenation methods have been more preferred.

[0004] In the prior art, when liquid-phase hydrogenation of mixed aldehydes is performed, the mixed aldehydes are usually sent into a reactor together. Low-molecular aldehydes with a carbon number less than 6 and high-molecular aldehydes with a carbon number greater than or equal to 8, especially olefinic aldehydes with conjugated double bonds, react to generate high-boiling products during the mixing process, so it is very necessary to control the mixing time of the two. In addition, the prior art usually reacts the low-molecular aldehydes and the high-molecular aldehydes under the same reaction conditions after the mixed aldehydes are sent into the reactor, and fails to distinguish them according to the difference in the reaction characteristics of the two aldehydes. In this way, in order to obtain a higher conversion rate of the high-molecular aldehyde, the mixed aldehydes need to be hydrogenated at a higher temperature together, which not only causes dimerization or trimerization of some low-molecular aldehydes to generate high-boiling products, but also causes some low-molecular aldehydes to react with the high-molecular aldehydes, especially when the high-molecular aldehydes are olefinic aldehydes with conjugated double bonds (such as butyraldehyde and octenal; valeraldehyde and decenal). For an industrial plant with an annual production capacity of 200,000 tons of butanol, even if only 1% of butyraldehyde reacts with octenal (or dimerizes), the economic loss will exceed 20 million per year. Therefore, it is of great significance to provide a method for liquid phase hydrogenation of mixed aldehydes to reduce the loss of aldehydes by controlling the reaction conditions.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The first object of the present invention is to provide a method for preparing alcohol by liquid phase hydrogenation of mixed aldehydes, aiming to solve the technical problem that in the prior art, when high molecular weight aldehydes and low molecular weight aldehydes enter the reactor together for liquid phase hydrogenation, they are all carried out at a higher temperature suitable for high molecular weight aldehydes, resulting in high content of high boiling points in the product and large aldehyde loss. The present invention can effectively reduce the content of high boiling points in the product, reduce the loss of aldehydes, and improve the yield of product alcohol by performing two-step liquid phase hydrogenation on the mixed aldehydes, controlling the reaction temperature in stages, and reasonably controlling the conditions of the two-step liquid phase hydrogenation.

[0007] The second object of the present invention is to provide a device for preparing alcohol by liquid-phase hydrogenation of mixed aldehydes, which is suitable for the method for preparing alcohol by liquid-phase hydrogenation of mixed aldehydes as described above.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0009] A method for preparing alcohol by liquid phase hydrogenation of mixed aldehydes comprises the following steps:

[0010] The mixed aldehyde is subjected to a first liquid phase hydrogenation reaction with hydrogen, and a portion of the obtained first hydrogenation product is circulated to the feed inlet of the first liquid phase hydrogenation reaction to be mixed with the mixed aldehyde and hydrogen; the remaining first hydrogenation product is subjected to a second liquid phase hydrogenation reaction with hydrogen, and a portion of the obtained second hydrogenation product is circulated to the feed inlet of the second liquid phase hydrogenation reaction to be mixed with the first hydrogenation product and hydrogen, and the remaining second hydrogenation product is discharged as a crude alcohol product;

[0011] Wherein, the mixed aldehyde comprises a first aldehyde having a carbon number not higher than 6 and a second aldehyde having a carbon number not lower than 8;

[0012] The inlet temperature of the first liquid phase hydrogenation reaction is 90-125°C, and the inlet and outlet temperature difference of the first liquid phase hydrogenation reaction does not exceed 10°C;

[0013] The inlet temperature of the second liquid phase hydrogenation reaction is 120-160°C, and the inlet and outlet temperature difference of the second liquid phase hydrogenation reaction does not exceed 10°C.

[0014] A device for preparing alcohol by liquid-phase hydrogenation of mixed aldehydes is applicable to the method for preparing alcohol by liquid-phase hydrogenation of mixed aldehydes as described above, comprising a mixed aldehyde storage tank, a first hydrogenation reactor and a second hydrogenation reactor, wherein the inlet of the first hydrogenation reactor is respectively connected to the outlet of the mixed aldehyde storage tank and a hydrogen source, the outlet of the first hydrogenation reactor is connected to a first gas-liquid separation tank, the liquid phase outlet of the first gas-liquid separation tank is respectively connected to the inlet of the first hydrogenation reactor and the inlet of the second hydrogenation reactor, the inlet of the second hydrogenation reactor is connected to the hydrogen source, the outlet of the second hydrogenation reactor is connected to a second gas-liquid separation tank, and the liquid phase outlet of the second gas-liquid separation tank is respectively connected to the inlet of the second hydrogenation reactor and a crude alcohol product discharge pipe.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The method of the present invention uses two-step liquid phase hydrogenation to control the reaction conditions in stages. First, the vast majority of low molecular aldehydes (first aldehydes) are converted into alcohols through the first liquid phase hydrogenation reaction, and most of the C8 or C8 aldehydes, especially olefins, are converted into alcohols or partially hydrogenated olefins to reduce their polymerization activity. Then, the remaining unhydrogenated C8 or C8 unsaturated substances are hydrogenated through the second liquid phase hydrogenation reaction to obtain a higher aldehyde conversion rate while reducing the loss of the aldehyde polymerization reaction. The method of the present invention can reduce the generation of heavy components and obtain a higher aldehyde conversion rate and the selectivity of the corresponding alkanol. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A reaction flow chart provided for an embodiment of the present invention;

[0019] Figure 2 A schematic diagram of a device for preparing alcohols by hydrogenating mixed aldehydes provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0021] like Figure 1 As shown, the first aspect of the present invention provides a method for preparing alcohol by liquid phase hydrogenation of mixed aldehydes, comprising the following steps:

[0022] The mixed aldehyde and hydrogen undergo a first liquid phase hydrogenation reaction, and a portion of the obtained first hydrogenation product is circulated to the raw material inlet of the first liquid phase hydrogenation reaction to be mixed with the mixed aldehyde and hydrogen; the remaining first hydrogenation product undergoes a second liquid phase hydrogenation reaction with hydrogen, and a portion of the obtained second hydrogenation product is circulated to the raw material inlet of the second liquid phase hydrogenation reaction to be mixed with the first hydrogenation product and hydrogen, and the remaining second hydrogenation product is discharged as a crude alcohol product;

[0023] wherein the mixed aldehyde comprises a first aldehyde having no more than 6 carbon atoms and a second aldehyde having no less than 8 carbon atoms;

[0024] The inlet temperature of the first liquid phase hydrogenation reaction is 90-125°C, and the inlet and outlet temperature difference of the first liquid phase hydrogenation reaction does not exceed 10°C;

[0025] The inlet temperature of the second liquid phase hydrogenation reaction is 120-160°C, and the inlet and outlet temperature difference of the second liquid phase hydrogenation reaction does not exceed 10°C.

[0026] The invention provides a method for preparing alcohol by liquid phase hydrogenation of a mixture containing a low molecular aldehyde (a first aldehyde) and a high molecular aldehyde (a second aldehyde), aiming at reducing aldehyde loss and improving the yield of product alcohol. The method of the invention aims at different reaction characteristics of low molecular aldehyde and high molecular aldehyde in the mixed aldehyde, and controls the reaction conditions of liquid phase hydrogenation in sections through two-step liquid phase hydrogenation reaction. Firstly, most of the low molecular aldehyde is converted into alcohol through the first liquid phase hydrogenation reaction, and most of the high molecular aldehyde, especially olefinic aldehyde, is converted into alcohol or partially hydrogenated olefinic alcohol to reduce the activity of polymerization. Then, the remaining unhydrogenated C8 or above unsaturated substances are hydrogenated through the second liquid phase hydrogenation reaction to reduce the generation of heavy components, reduce the aldehyde loss caused by aldehyde polymerization reaction, and obtain a higher aldehyde conversion rate and selectivity of corresponding alkanol.

[0027] The inlet and outlet temperature difference of the first liquid phase hydrogenation reaction and the inlet and outlet temperature difference of the second liquid phase hydrogenation reaction have an important influence on aldehyde polymerization. Too large a temperature difference will lead to an increase in the content of high boiling points in the product. The present invention can effectively reduce the content of high boiling points in the product and improve the conversion rate of aldehyde and the yield of corresponding alcohol by reasonably controlling the inlet and outlet temperature difference of the first liquid phase hydrogenation reaction and the second liquid phase hydrogenation reaction to not exceed 10°C.

[0028] In some embodiments, typically but not limiting, for example, the inlet and outlet temperature difference of the first liquid-phase hydrogenation reaction and the inlet and outlet temperature difference of the second liquid-phase hydrogenation reaction can be independently set to any point value among 10°C, 9°C, 8°C, 7°C, 6°C, 5°C, 4°C, 3°C, 2°C, 1°C, and 0°C, or a range value consisting of any two point values.

[0029] In some specific embodiments of the present invention, the inlet and outlet temperature difference of the second liquid-phase hydrogenation reaction is smaller than the inlet and outlet temperature difference of the first liquid-phase hydrogenation reaction. Generally, the temperature of the second liquid-phase hydrogenation reaction is higher and it is relatively easier to generate high-boiling substances. Therefore, a smaller inlet and outlet temperature difference of the second liquid-phase hydrogenation reaction is beneficial to reducing the content of high-boiling substances in the product.

[0030] In some specific embodiments of the present invention, the catalyst for the first liquid-phase hydrogenation reaction and the catalyst for the second liquid-phase hydrogenation reaction are independently selected from copper-based catalysts or nickel-based catalysts.

[0031] In some specific embodiments of the present invention, the copper-based catalyst can be a copper-chromium, copper-zinc or copper-titanium catalyst, or a composite oxide catalyst composed of the above catalysts and other metal oxides, or a supported catalyst based on the above combination; the nickel-based catalyst can be a Raney nickel, nickel-copper, nickel-aluminum or nickel-magnesium catalyst, or a composite oxide catalyst composed of the above catalysts and other metal oxides, or a supported catalyst based on the above combination.

[0032] The inlet temperature of the first liquid-phase hydrogenation reaction and the second liquid-phase hydrogenation reaction is related to the catalyst used. When the catalyst of the first liquid-phase hydrogenation reaction is a copper-based catalyst, the inlet temperature of the first liquid-phase hydrogenation reaction is 110-125°C, for example, it can be any point value of 110°C, 112°C, 115°C, 116°C, 118°C, 120°C, 125°C or a range value composed of any two point values; when the catalyst of the first liquid-phase hydrogenation reaction is a nickel-based catalyst, the inlet temperature of the first liquid-phase hydrogenation reaction is 90-120°C, for example, it can be 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 116°C, 118°C, 120°C, 125°C. 20 ℃ or any two point values ​​in the inlet temperature range; when the catalyst for the second liquid-phase hydrogenation reaction is a copper-based catalyst, the inlet temperature of the second liquid-phase hydrogenation reaction is 140-160 ℃, for example, it can be any point value among 140 ℃, 145 ℃, 148 ℃, 150 ℃, 155 ℃, and 160 ℃ or any two point values ​​in the inlet temperature range; when the catalyst for the second liquid-phase hydrogenation reaction is a nickel-based catalyst, the inlet temperature of the second liquid-phase hydrogenation reaction is 120-140 ℃, for example, it can be any point value among 120 ℃, 125 ℃, 130 ℃, 135 ℃, and 140 ℃ or any two point values ​​in the inlet temperature range.

[0033] In some specific embodiments of the present invention, in the mixed aldehydes, the mass percentage of the first aldehyde is 20%-80%. For example, the mass percentage of the first aldehyde can be any point value among 20%, 30%, 40%, 50%, 60%, 70%, 80% or a range value consisting of any two point values.

[0034] In some specific embodiments of the present invention, the first aldehyde includes at least one of n-butyraldehyde, isobutyraldehyde, n-valeraldehyde, and isovaleraldehyde.

[0035] In some specific embodiments of the present invention, the second aldehyde includes at least one of 2-propyl-2-heptenal, 2-ethylhexenal, and isononanal. In other embodiments, the second aldehyde may also be other C8-C20 enal or aldehyde.

[0036] In some specific embodiments of the present invention, the alcohol prepared by hydrogenation of the mixed aldehydes of the present invention can be 2-propylheptanol, 2-ethylhexanol, n-butanol, isobutanol, isononanol or other C3-C20 alkanols.

[0037] In some specific embodiments of the present invention, the reaction pressure of the first liquid phase hydrogenation reaction is 2.0-5.0 MPa. For example, it can be any point value among 2.0 MPa, 2.3 MPa, 2.6 MPa, 2.9 MPa, 3.0 MPa, 3.2 MPa, 3.5 MPa, 4.0 MPa, 4.5 MPa, and 5.0 MPa, or a range value consisting of any two point values.

[0038] In some specific embodiments of the present invention, the reaction pressure of the second liquid phase hydrogenation reaction is 2.0-5.0 MPa. For example, it can be any point value among 2.0 MPa, 2.2 MPa, 2.55 MPa, 2.85 MPa, 3.0 MPa, 3.2 MPa, 3.4 MPa, 4.0 MPa, 4.5 MPa, and 5.0 MPa, or a range value consisting of any two point values.

[0039] In some specific embodiments of the present invention, the reaction pressure of the second liquid phase hydrogenation reaction is 0.05-0.1 MPa lower than the reaction pressure of the first liquid phase hydrogenation reaction.

[0040] In some specific embodiments of the present invention, the mass ratio of the first hydrogenation product and the mixed aldehyde feed flow circulated to the first liquid phase hydrogenation reaction raw material inlet is 5-30:1, for example, it can be any point value among 5:1, 10:1, 15:1, 20:1, 23:1, 25:1, 30:1 or a range value composed of any two point values. The flow rate of the circulating logistics is used for withdrawing reaction heat and controlling the temperature difference between the reactor outlet and the inlet. The lower the temperature difference to be controlled, the larger the circulation amount.

[0041] In some specific embodiments of the present invention, the mass ratio of the second hydrogenated product circulated to the raw material inlet of the second liquid phase hydrogenation reaction to the feed flow of the first hydrogenated product entering the second liquid phase hydrogenation reaction is 5-15:1, for example, it can be any point value among 5:1, 7.5:1, 10:1, 12.5:1, 15:1 or a range value composed of any two point values. The flow rate of the circulating logistics is used for withdrawing reaction heat and controlling the temperature difference between the reactor outlet and the inlet. The lower the temperature difference to be controlled, the larger the circulation amount.

[0042] In some specific embodiments of the present invention, in the first liquid phase hydrogenation reaction, the liquid phase feed space velocity of the mixed aldehyde is 0.1-3.0 hr -1 When using copper-based catalyst, the feed space velocity range is preferably 0.6-3hr -1 When using nickel-based catalyst, the feed space velocity range is preferably 0.1-2.0 hr -1 ;

[0043] And / or, in the second liquid phase hydrogenation reaction, the feed space velocity of the first hydrogenation product is 0.2-5.5hr -1 When using copper-based catalysts, the feed space velocity range is preferably 0.3-5.5hr -1 When using nickel-based catalyst, the feed space velocity range is preferably 0.2-2.5hr -1 .

[0044] The liquid phase space velocity of the mixed aldehyde in the catalyst bed of the first liquid phase hydrogenation reactor (R-1) and the second liquid phase hydrogenation reactor (R-2) is related to the content of the low molecular weight aldehyde (first aldehyde) therein. The recommended space velocity range can be seen in Table 1:

[0045] Table 1

[0046]

[0047]

[0048] In some specific embodiments of the present invention, in the first liquid phase hydrogenation reaction, the conversion rate of the first aldehyde is greater than 90%, for example, it can be 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and the like; the conversion rate of the second aldehyde is greater than 50%, for example, it can be 55%, 60%, 65%, 67%, 70%, 75%, 77%, 79%, 80% and the like; in the second liquid phase hydrogenation reaction, the conversion rate of the first aldehyde is greater than 95%, for example, it can be 96%, 97%, 98%, 99% and the like; the conversion rate of the second aldehyde is greater than 95%, for example, it can be 96%, 97%, 98%, 99% and the like.

[0049] like Figure 2 As shown, the second aspect of the present invention provides a device for preparing alcohol by liquid-phase hydrogenation of mixed aldehydes, which is suitable for the method for preparing alcohol by liquid-phase hydrogenation of mixed aldehydes described in any one of the aforementioned embodiments, comprising a mixed aldehyde storage tank V-1, a first hydrogenation reactor R-1 and a second hydrogenation reactor R-2, the inlet of the first hydrogenation reactor R-1 is connected to the outlet of the mixed aldehyde storage tank V-1 and the hydrogen source through pipelines, the outlet of the first hydrogenation reactor R-1 is connected to the first gas-liquid separation tank V-2, the liquid phase outlet of the first gas-liquid separation tank V-2 is connected to the inlet of the first hydrogenation reactor R-1 and the second hydrogenation reactor R-2 through pipelines, the inlet of the second hydrogenation reactor R-2 is connected to the hydrogen source through a pipeline, the outlet of the second hydrogenation reactor R-2 is connected to the second gas-liquid separation tank V-3, and the liquid phase outlet of the second gas-liquid separation tank V-3 is connected to the inlet of the second hydrogenation reactor R-2 and the crude alcohol product discharge pipe through pipelines.

[0050] The working process of the above-mentioned device is as follows: the mixed aldehyde in the mixed aldehyde storage tank V-1 is pressurized by the pump P-1 through the pipeline 113 and passes through the pipeline 102, and is mixed with the hydrogen from the hydrogen pipeline 101 (the flow rate is controlled by the mass flowmeter F-1) in the pipeline 103. After the mixture of the mixed aldehyde and the hydrogen is mixed with the first hydrogenation product from the pipeline 110, they enter the reactor together from the upper part of the first hydrogenation reactor R-1 through the pipeline 104. The first hydrogenation reactor R-1 is equipped with the required hydrogenation catalyst. The mixed flow after the first hydrogenation reaction is sent to the first gas-liquid separation tank V-2 through pipeline 105, and a small amount of unreacted hydrogen is discharged from the top pipeline 106. The first hydrogenation product (liquid phase) is divided into two paths after passing through the bottom pipeline 107. Most of it passes through pipeline 108, pump P-2, pipeline 109, and then passes through heat exchanger HX-1 for cooling, and then passes through pipeline 110 to mix with the mixture of hydrogen and mixed aldehydes from pipeline 103, and then enters the first hydrogenation reactor R-1 through pipeline 104; the other path passes through pipeline 112 and mixes with hydrogen from hydrogen pipeline 111 (measured by mass flow meter F-2 The second hydrogenation product from pipeline 208 enters the second hydrogenation reactor R-2 together, and the product flow after the second hydrogenation is sent to the second gas-liquid separation tank V-3 through pipeline 203, and a small amount of unreacted hydrogen is discharged from the top pipeline 204. The second hydrogenation product (liquid phase) is divided into two paths after passing through the bottom pipeline 205. Most of it passes through pipeline 206, pump P-3 and pipeline 207 and then passes through heat exchanger HX-2 for cooling, and then passes through pipeline 208 and is mixed with the mixture of hydrogen from pipeline 201 and the first hydrogenation product and enters the second hydrogenation reactor R-2 through pipeline 202. The other path is discharged as a crude alcohol product through pipeline 209. Crude alcohol usually needs to be separated from heavy components and light components by distillation, and may also need to be refined hydrogenated to ensure that a small amount of unsaturated substances are completely saturated to ensure the chromaticity of the product. The refined hydrogenation process can be before the distillation de-heavy (or de-light) or after the distillation de-heavy (or de-light).

[0051] In order to allow the liquid phase flow in the first gas-liquid separation tank V-2 to smoothly enter the second hydrogenation reactor R-2, the operating pressure of the second hydrogenation reactor R-2 is usually controlled to be slightly lower than the operating pressure of the first hydrogenation reactor R-1, generally 0.05-0.1MPa lower.

[0052] In some specific embodiments of the present invention, a balance W-1 is installed at the bottom of the mixed aldehyde storage tank V-1 to measure the feed flow rate of the mixed aldehyde.

[0053] The following is a detailed description of some embodiments of the present invention in conjunction with specific examples. The raw materials used in the examples can be purchased from the market unless otherwise specified.

[0054] Example 1

[0055] Implementation 1 Use Figure 2 In the test device shown, the mixed aldehyde (approximate mass composition: isobutyraldehyde 2.4%, normal butyraldehyde 67%, C10 olefinic aldehyde 29.5%, valeraldehyde 0.5%, C9 alcohol 0.1%, high boiling point 0.5%, density about 0.8 g / ml) is pressurized by pump P-1 from mixed aldehyde storage tank V-1 through pipeline 113 at a flow rate of 120 g / h, mixed with hydrogen (about 35 NL / h) from mass flow meter F-1, and then mixed with the first hydrogenation product circulation flow (1800±200 g / h) from pipeline 110 through pipeline 103, and then mixed with hydrogen (about 35 NL / h) from pipeline 110 through static mixing. After mixing in the combiner S-1, the mixture enters the reactor from the top of the first hydrogenation reactor R-1 through pipeline 104. The first hydrogenation reactor R-1 is equipped with 120 ml of copper-chromium catalyst (catalyst precursor CuO: Cr2O3 = 6:4, prepared by co-precipitation, and reduced in situ with hydrogen at 170-180°C before use). The operating pressure is 2.9 MPa (absolute pressure), the inlet temperature is 115°C, and the outlet temperature is 124°C. The first liquid phase hydrogenation reaction product flows through pipeline 105 into the first gas-liquid separation tank V-2, and a small amount of unreacted hydrogen is condensed by cooling water from pipeline 106 ( Figure 2 The liquid phase product is discharged as tail gas after being cooled by pump P-2 and heat exchanger HX-1, mixed with mixed aldehyde feed and returned to the first hydrogenation reactor R-1, and part of it is used as the first hydrogenation product through pipeline 112 (about 122-125 g / h, the flow rate is automatically controlled by a regulating valve associated with the liquid level of the gas-liquid separation tank, the same below), mixed with hydrogen from mass flow meter F-2 in pipeline 201, and the mixture is then mixed with the second liquid phase hydrogenation reaction cycle from 208 The product stream (600±100g / h) is mixed, mixed in the static mixer S-2, and then enters the top of the second hydrogenation reactor R-2 through pipeline 202. The second hydrogenation reactor R-2 is equipped with 80ml of the same copper-chromium catalyst as that in R-1, the operating pressure is 2.85MPa (absolute pressure), the inlet temperature is 150°C, and the reaction product stream (outlet temperature 160°C) enters the second gas-liquid separation tank V-3 through pipeline 203. A small amount of unreacted hydrogen is condensed by cooling water from pipeline 204 ( Figure 2 Most of the liquid products are cooled by pump P-3 and heat exchanger HX-2, mixed with the first hydrogenation product feed, and then returned to the second hydrogenation reactor R-2. Part of them are extracted as crude alcohol product through pipeline 209.

[0056] Example 2

[0057] Example 2 is similar to Example 1, except that: in the first hydrogenation reactor R-1, the operating pressure is 2.6 MPa (absolute pressure), the inlet temperature is 116°C, the outlet temperature is 121°C, and the circulating product flow is 2800±200 g / h; in the second hydrogenation reactor R-2, the operating pressure is 2.55 MPa (absolute pressure), the inlet temperature is 150°C, the outlet temperature is 155°C, and the circulating product flow is 1200±200 g / h. The other conditions are the same as in Example 1.

[0058] Example 3

[0059] Example 3 is similar to Example 1, except that: mixed aldehyde feed is 120 g / h (approximately composed by mass: isobutyraldehyde 1.9%, n-butyraldehyde 47.6%, C10 olefinic aldehyde 49.5%, valeraldehyde 0.5%, high boiling point 0.5%, density about 0.8 g / ml), in the first hydrogenation reactor R-1, the copper-chromium catalyst loading is 100 ml, the inlet temperature is 115° C., the outlet temperature is 120° C., and the circulating product flow is 2000±200 g / h; in the second hydrogenation reactor R-2, the copper-chromium catalyst loading is 140 ml, the inlet temperature is 148° C., the outlet temperature is 153° C., the circulating product flow is 1800±200 g / h, and the other conditions are the same as in Example 1.

[0060] Example 4

[0061] Example 4 is similar to Example 3, except that the catalysts used in the two reactors are Ni / Al2O3 catalysts (catalyst precursor NiO loading of about 40wt%, prepared by impregnation method, and reduced with hydrogen at 300°C before use); in the first hydrogenation reactor R-1, the catalyst loading is 180ml, the reactor pressure is 3.5MPa (absolute pressure), the reactor inlet temperature is 100°C, the outlet temperature is 105°C, and the hydrogenation product circulation amount is about 1800±200g / h; in the second hydrogenation reactor R-2, the catalyst loading is 280ml, the reactor pressure is 3.4MPa (absolute pressure), the reactor inlet temperature is 120°C, the outlet temperature is 125°C, and the hydrogenation product circulation amount is about 900±100g / h, and the other conditions are the same as in Example 3.

[0062] Example 5

[0063] Example 5 is similar to Example 1, except that: a mixed aldehyde feed of 120 g / h (approximately by mass: 2-methylbutyraldehyde 1.1%, n-valeraldehyde 28.5%, octenal 69%, butyraldehyde 0.9%, high boiling point 0.5%, density about 0.8 g / ml), a Ni / SiO2 catalyst (catalyst precursor NiO loading of about 35 wt%, prepared by impregnation method, pre-reduced by hydrogen at 260°C before use, and then reduced in situ at 170-180°C in the test device) is used in the first hydrogenation reactor R-1, a catalyst loading of 160 ml, and a reactor pressure of 3 .0MPa (absolute pressure), reactor inlet temperature 100°C, outlet temperature 105°C, hydrogenation product circulation rate of about 600±100g / h; in the second hydrogenation reactor R-2, copper-titanium catalyst (catalyst precursor CuO:TiO2=55:45, prepared by gel method, in situ reduced with hydrogen at 170-180°C before use) was used, filling amount 240ml, reactor pressure 3.0MPa (absolute pressure), inlet temperature 150°C, outlet temperature 155°C, hydrogenation product circulation rate (about 1800±200g / h), and other conditions were the same as those in Example 1.

[0064] Comparative Example 1a

[0065] Comparative Example 1a is similar to Example 1, except that: Comparative Example 1a only uses Figure 2 The R-1 reactor (one-step liquefaction hydrogenation) in the test device shown has a catalyst loading of 200 ml, a reactor inlet temperature of 150° C., an outlet temperature of 165° C., a hydrogenation product circulation rate of about 2000±200 g / h, and other conditions are the same as in Example 1.

[0066] Comparative Example 1b

[0067] Comparative Example 1b is similar to Example 1, except that: Comparative Example 1b only uses Figure 2 The R-1 reactor (one-step liquefaction hydrogenation) in the test device shown has a catalyst loading of 200 ml, a reactor inlet temperature of 150° C., an outlet temperature of 160° C., a hydrogenation product circulation rate of about 2600±200 g / h, and other conditions are the same as in Example 1.

[0068] Comparative Example 1c

[0069] Comparative Example 1c is similar to Example 1, except that: in the first hydrogenation reactor R-1, the inlet temperature is 115°C, and the outlet temperature is 135°C; in the second hydrogenation reactor R-2, the inlet temperature is 150°C, and the outlet temperature is 160°C. The other conditions are the same as in Example 1.

[0070] Comparative Example 1d

[0071] Comparative Example 1d is similar to Example 1, except that: in the first hydrogenation reactor R-1, the inlet temperature is 115°C, and the outlet temperature is 124°C; in the second hydrogenation reactor R-2, the inlet temperature is 150°C, and the outlet temperature is 170°C. The other conditions are the same as in Example 1.

[0072] Comparative Example 2a

[0073] Comparative Example 2a is similar to Example 3, except that: Comparative Example 2a only uses Figure 2 The R-1 reactor in the test device shown (one-step liquid phase hydrogenation) has a catalyst loading of 240 ml, a reactor inlet temperature of 150°C, an outlet temperature of 165°C, a hydrogenation product circulation rate of about 2200±200 g / h, and other conditions are the same as in Example 3.

[0074] Comparative Example 2b

[0075] Comparative Example 2b is similar to Example 3, except that: Comparative Example 2b only uses Figure 2 The R-1 reactor in the test device shown (one-step liquid phase hydrogenation) has a catalyst loading of 240 ml, a reactor inlet temperature of 148° C., an outlet temperature of 153° C., a hydrogenation product circulation rate of about 2600±200 g / hg / h, and the other conditions are the same as in Example 3.

[0076] Comparative Example 3a

[0077] Comparative Example 3a is similar to Example 4, except that: Comparative Example 3a only uses Figure 2 The R-1 reactor in the test device shown (one-step liquid phase hydrogenation) has a catalyst loading of 460 ml, a reactor inlet temperature of 110° C., an outlet temperature of 130° C., a hydrogenation product circulation rate of about 1500±200 / h, and other conditions are the same as in Example 4.

[0078] Comparative Example 3b

[0079] Comparative Example 3b is similar to Example 4, except that: Comparative Example 3b only uses Figure 2 The R-1 reactor in the test device shown (one-step liquid phase hydrogenation) has a catalyst loading of 460 ml, a reactor inlet temperature of 120° C., an outlet temperature of 125° C., a hydrogenation product circulation rate of about 3000±200 g / h, and other conditions are the same as in Example 4.

[0080] Comparative Example 4

[0081] Comparative Example 4 is similar to Example 5, except that: Comparative Example 4 uses Figure 2In the R-1 reactor of the test device shown, the catalyst is loaded in two sections, the upper section is loaded with 160 ml of Ni / SiO2 catalyst, and the lower section is loaded with 240 ml of copper-titanium catalyst (catalyst precursor mass ratio CuO:TiO=60:40), the reactor pressure is 3 MPa, the reactor inlet temperature is 120°C, the outlet is 160°C, the hydrogenation product circulation volume is about 2600±200 g / h, and the other conditions are the same as Example 5.

[0082] Test example

[0083] The product compositions in the embodiments and comparative examples were tested respectively, and the test results are shown in Table 2, Table 3 and Table 4.

[0084] Table 2

[0085]

[0086]

[0087] Table 3

[0088]

[0089] As can be seen from the data in Table 2 and Table 3, low molecular weight butyraldehyde is substantially hydrogenated in the first reaction zone, and most of the C10 olefinic aldehydes are also at least partially hydrogenated in the first hydrogenation reactor, so that the active butyraldehyde and C10 olefinic aldehyde concentrations in the raw material entering the second hydrogenation reactor are relatively low, and the generation of high-boiling substances above C12 can be reduced under the conditions of the second hydrogenation reaction after the improvement. In the embodiment, relative to the comparative example, the heavy components of the hydrogenated product C12 and above are significantly reduced, and the C8 alcohol ester generated by the butyraldehyde dimerization hydrogenation is also significantly reduced (the specific value is related to the butyraldehyde content in the raw material), and the method adopted in the embodiment of the present invention improves the selectivity of the raw material, thereby improving the yield of the target product C10 alcohol. Although the control of the reactor outlet temperature causes the partial hydrogenation product C10 olefinic aldehyde in the embodiment product to increase compared with the comparative example, the substance can be converted into the target product C10 alcohol by subsequent refined hydrogenation. In the comparative example, since butyraldehyde and C10 olefinic aldehyde are directly hydrogenated at a relatively high temperature, the product contains a large amount of high-boiling substances above C12, which are difficult to remove by conventional refining and hydrogenation methods. High-boiling substances above C12 can be decomposed into small molecular alcohols by high-temperature cracking and hydrogenation. However, high temperature will also cause the decomposition of part of the target product C10 alcohol, which will lead to a decrease in the overall yield of the target product.

[0090] The comparison between Example 1-2 and Comparative Examples 1c and 1d shows that the temperature difference between the inlet and outlet of the two-stage liquid phase hydrogenation reaction is a relatively important parameter during the reaction. At the same inlet temperature, a large temperature difference will cause more heavy components to be produced, resulting in a decrease in product selectivity. If the temperature difference between the inlet and outlet of the first stage liquid phase hydrogenation is too high, the content of C8 esters and C12-C16 high boiling products will increase significantly, and if the temperature difference between the inlet and outlet of the second stage liquid phase hydrogenation is too high, the content of high boiling products above C20 will increase significantly.

[0091] Table 4

[0092]

[0093] It can be seen from the data in Table 4 that during the hydrogenation process of the mixture of valeraldehyde and octenal (C8 enal), dimerization of valeraldehyde itself and dimerization of valeraldehyde and octenal will also occur, resulting in the generation of by-products with higher molecular weight. The staged liquid phase hydrogenation method of the embodiment effectively reduces the content of high boiling points above C10 relative to the comparative example. Although the content of the target product C8 alcohol in the product stream of Example 5 is slightly lower than that of the comparative example, the total C8 alcohol content after subsequent refining and hydrogenation will be higher than that of the comparative example when the contents of the effective component intermediate products C8 aldehyde and C8 enol are added.

[0094] From the above discussion, it can be seen that the method of the present invention is based on the different reaction characteristics of high-molecular aldehydes and low-molecular aldehydes. It carries out liquefaction hydrogenation in two steps, controls the hydrogenation conditions in stages, and reasonably controls the inlet and outlet temperature difference of the two-stage hydrogenation reaction. It can significantly reduce the content of high-boiling substances produced by aldehyde polymerization, reduce the generation of heavy components, reduce aldehyde losses, and obtain a higher aldehyde conversion rate and selectivity of the corresponding alkanol.

[0095] Although the present invention has been illustrated and described with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents without departing from the spirit and scope of the present invention. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A method for preparing alcohols by liquid phase hydrogenation of mixed aldehydes, characterized in that: The following steps are involved: The mixed aldehyde is subjected to a first liquid phase hydrogenation reaction with hydrogen, and a portion of the obtained first hydrogenation product is circulated to the feed inlet of the first liquid phase hydrogenation reaction to be mixed with the mixed aldehyde and hydrogen; the remaining first hydrogenation product is subjected to a second liquid phase hydrogenation reaction with hydrogen, and a portion of the obtained second hydrogenation product is circulated to the feed inlet of the second liquid phase hydrogenation reaction to be mixed with the first hydrogenation product and hydrogen, and the remaining second hydrogenation product is discharged as a crude alcohol product; Wherein, the mixed aldehyde comprises a first aldehyde having a carbon number not higher than 6 and a second aldehyde having a carbon number not lower than 8; The inlet temperature of the first liquid phase hydrogenation reaction is 90-125°C, and the inlet and outlet temperature difference of the first liquid phase hydrogenation reaction does not exceed 10°C; The inlet temperature of the second liquid phase hydrogenation reaction is 120-160°C, and the inlet and outlet temperature difference of the second liquid phase hydrogenation reaction does not exceed 10°C.

2. The method for preparing alcohol by liquid phase hydrogenation of mixed aldehydes according to claim 1, characterized in that: The catalyst for the first liquid-phase hydrogenation reaction and the catalyst for the second liquid-phase hydrogenation reaction are independently selected from copper-based catalysts or nickel-based catalysts.

3. The method for preparing alcohol by liquid phase hydrogenation of mixed aldehydes according to claim 1, characterized in that: In the mixed aldehydes, the mass percentage of the first aldehyde is 20%-80%.

4. The method for preparing alcohol by liquid phase hydrogenation of mixed aldehydes according to claim 1, characterized in that: The first aldehyde comprises at least one of n-butyraldehyde, isobutyraldehyde, n-valeraldehyde, and isovaleraldehyde; And / or, the second aldehyde includes at least one of 2-propyl-2-heptenal, 2-ethylhexenal, and isononanal.

5. The method for preparing alcohol by liquid phase hydrogenation of mixed aldehydes according to claim 1, characterized in that: The reaction pressure of the first liquid phase hydrogenation reaction is 2.0-5.0 MPa; And / or, the reaction pressure of the second liquid phase hydrogenation reaction is 2.0-5.0 MPa.

6. The method for preparing alcohol by liquid phase hydrogenation of mixed aldehydes according to claim 1, characterized in that: The mass ratio of the first hydrogenation product circulated to the first liquid phase hydrogenation reaction raw material inlet to the feed stream of the mixed aldehyde is 5-30:

1.

7. The method for preparing alcohol by liquid phase hydrogenation of mixed aldehydes according to claim 1, characterized in that: The mass ratio of the feed flow of the second hydrogenated product circulated to the raw material inlet of the second liquid phase hydrogenation reaction to the feed flow of the first hydrogenated product entering the second liquid phase hydrogenation reaction is 5-15:

1.

8. The method for preparing alcohol by liquid phase hydrogenation of mixed aldehydes according to claim 1, characterized in that: In the first liquid phase hydrogenation reaction, the liquid phase feed space velocity of the mixed aldehyde is 0.1-3.0 hr -1 ; And / or, in the second liquid phase hydrogenation reaction, the feed space velocity of the first hydrogenation product is 0.2-5.5hr -1 .

9. The method for preparing alcohol by liquid phase hydrogenation of mixed aldehydes according to claim 1, characterized in that: In the first liquid phase hydrogenation reaction, the conversion rate of the first aldehyde is greater than 90%, and the conversion rate of the second aldehyde is greater than 50%; in the second liquid phase hydrogenation reaction, the conversion rate of the first aldehyde is greater than 95%, and the conversion rate of the second aldehyde is greater than 95%.

10. A device for preparing alcohols by liquid phase hydrogenation of mixed aldehydes, characterized in that: A method for preparing alcohol by liquid-phase hydrogenation of mixed aldehydes applicable to any one of claims 1 to 9, comprising a mixed aldehyde storage tank, a first hydrogenation reactor and a second hydrogenation reactor, wherein the inlet of the first hydrogenation reactor is respectively connected to the outlet of the mixed aldehyde storage tank and a hydrogen source, the outlet of the first hydrogenation reactor is connected to a first gas-liquid separation tank, the liquid phase outlet of the first gas-liquid separation tank is respectively connected to the inlets of the first hydrogenation reactor and the second hydrogenation reactor, the inlet of the second hydrogenation reactor is connected to the hydrogen source, the outlet of the second hydrogenation reactor is connected to a second gas-liquid separation tank, and the liquid phase outlet of the second gas-liquid separation tank is respectively connected to the inlet of the second hydrogenation reactor and a crude alcohol product discharge pipe.

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