Process for the preparation of 1,3-propanediol and product

Abstract

The application provides a preparation method and product of 1,3-propanediol. The preparation method comprises the following steps: subjecting 3-hydroxypropionaldehyde aqueous solution to a first-stage hydrogenation reaction under the action of a first-stage hydrogenation catalyst to obtain a first-stage hydrogenation reaction product; and subjecting the first-stage hydrogenation reaction product to a second-stage reaction under the action of a second-stage hydrogenation catalyst to obtain a 1,3-propanediol product. The preparation method adopts two-stage hydrogenation, effectively improves the economy of the propenal hydration hydrogenation process, and solves the problems that the impurities generated in the 1,3-propanediol preparation route of the propenal hydration process are difficult to treat and resource utilization.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of petroleum chemical industry, in particular to a preparation method and product of 1,3-propanediol. BACKGROUND

[0002] 1,3-propanediol (1,3-PDO) is an important organic chemical raw material, which is mainly used for producing polytrimethylene terephthalate (PTT). Meanwhile, 1,3-PDO has excellent moisturizing performance and antibacterial properties, low biological toxicity, high low-temperature stability, and is widely used in the fields of cosmetics, ink, printing and dyeing, paint and lubricant, etc.

[0003] Propylene aldehyde hydration hydrogenation is one of the important methods for preparing 1,3-propanediol. In this method, propylene aldehyde reacts with water under the action of an acid catalyst to generate 3-hydroxypropionaldehyde, and then 3-hydroxypropionaldehyde is hydrogenated to generate 1,3-propanediol. The commonly used acid catalysts in the hydration process are liquid acids (sulfuric acid, hydrochloric acid, phosphoric acid, acetic acid, etc.) and solid acids (acidic molecular sieve, acidic resin, etc.). While generating 3-hydroxypropionaldehyde, propylene aldehyde and 3-hydroxypropionaldehyde are prone to intermolecular condensation under the action of acid to generate 4-hetero-oxy heptanediol, which is hydrogenated to generate 4-hetero-oxy heptanediol, resulting in low selectivity of 3-hydroxypropionaldehyde in the hydration step, and further affecting the product yield of 1,3-PDO after hydrogenation. At the same time, 3-hydroxypropionaldehyde and 1,3-propanediol will undergo condensation reaction to generate 1,3-dioxane-2-ethanol during hydrogenation, which not only reduces the yield of 1,3-PDO, but also increases the difficulty of separation and purification of 1,3-PDO. The main side reaction equations of hydration and hydrogenation processes are as follows:

[0004]

[0005] In the prior art process of preparing 3-hydroxypropanal by acrolein hydration, the actual selectivity of 3-hydroxypropanal is 80-90%; 4-hydroxyheptanedial impurities are inevitably produced at 4%-8%, and further hydrogenation will generate 4-hydroxyheptanediol, resulting in low yield of 1,3-PDO by acrolein hydration hydrogenation method. For example, the resin catalyst containing -NH-CH2-PO3H2 functional group on the surface disclosed in patent US5015789 has acrolein conversion rate of 40.2-63.72% and 3-hydroxypropanal selectivity of 71.0-82.0%; US5171898 discloses a chelating resin containing -CH2-N-(CH2COOH)2 functional group on the surface, and the selectivity of 3-hydroxypropanal is 80-85%; the article “Development and Research on New Technology of Acrolein Hydration Hydrogenation Process for Synthesizing 1,3-Propanediol” (Tang Yong. Development and Research on New Technology of Acrolein Hydration Hydrogenation Process for Synthesizing 1,3-Propanediol[D], East China University of Technology, 2014.) uses D751 resin as catalyst, and the selectivity of 3-hydroxypropanal is 89%; the selectivity of 1,3-PDO generated by hydrogenation is 98%, and the total yield of 1,3-PDO in two-step reaction is less than 90%.

[0006] 3-hydroxypropanal has high reactivity and is unstable, and is easily converted into acrolein through dehydration reversible reaction at high temperature, and impurities n-propanol are generated by hydrogenation. The prior art usually adopts two-stage fixed-bed hydrogenation, and the reaction is first carried out at low temperature, so that 70%-90% of 3-hydroxypropanal is converted into 1,3-propanediol, and then the hydrogenation reaction of low-concentration 3-hydroxypropanal is carried out at high temperature, so that it is completely converted. The prior art usually uses the same catalyst in two-stage hydrogenation, and although the conversion rate and selectivity of 3-hydroxypropanal can reach more than 98%, the yield is still relatively low due to the influence of impurities generated in the hydrogenation process, and the treatment of the series of impurities is not mentioned, which increases the difficulty of subsequent separation.

[0007] Patent CN100344370C discloses a Ni-Mo-A / X supported catalyst prepared by impregnation method, and adopts two-stage hydrogenation process (the same catalyst), the first-stage hydrogenation pressure is 5 MPa and the temperature is 50°C; the second-stage hydrogenation pressure is 5 MPa and the temperature is 120°C, 3-hydroxypropanal is hydrogenated to prepare 1,3-propanediol, the conversion rate of 3-hydroxypropanal is 99.4%, and the selectivity of 1,3-propanediol is 99.1%.

[0008] Patent CN1122568C discloses a Raney nickel type hydrogenation catalyst, which is composed of Al-Ni-A, wherein A is any one of Cr, Zn, Mo and Fe. In two-stage hydrogenation, the conversion rate and selectivity of 3-hydroxypropanal can reach more than 99%.

[0009] Patent CN1184181C discloses a catalyst with the composition of Ni-A, wherein A is any one of Cr, Zn, Mo, or Fe, the carrier is Al2O3 or SiO2, or a molecular sieve containing both. Under two-stage hydrogenation, the conversion rate and selectivity of 3-hydroxypropanal can reach nearly 100%.

[0010] Patent application CN1363544A discloses a preparation method of a catalyst for hydrogenation of 3-hydroxypropanal, which is prepared by impregnation method using a metal oxide, a zeolite molecular sieve, or a mixture of a metal oxide and a zeolite molecular sieve as a carrier, and an aqueous solution containing nickel salt and cobalt salt as an impregnation solution. The prepared catalyst uses one-stage hydrogenation, and the conversion rate of 3-hydroxypropanal is 78-99%, and the selectivity is 98-99%.

[0011] Patent CN100344370C discloses a Ni-Mo-X / A supported hydrogenation catalyst with a molecular sieve, an oxide, or a mixture of both as a carrier, and Ni, Mo, and a third metal as active components. The catalyst uses two-stage hydrogenation, and the conversion rate of 3-hydroxypropanal is 75-100%, and the selectivity is 43.2-100%.

[0012] Patent CN100500628C discloses a supported amorphous alloy hydrogenation catalyst. The catalyst uses two-stage hydrogenation, and the conversion rate of 3-hydroxypropanal is 84-100%, and the selectivity is 97-100%.

[0013] As can be seen from the above, the two-stage hydrogenation processes of 3-hydroxypropanal in the prior art mostly use the same catalyst, and the selectivity of 3-hydroxypropanal and 1,3-PDO can both reach more than 99%, but none of them mentions the reaction effect of impurities generated in the hydration and hydrogenation of propylene aldehyde in the hydrogenation stage, and how to further improve the yield of 1,3-PDO in the two steps of hydration and hydrogenation. SUMMARY

[0014] The main purpose of the present application is to provide a preparation method and product of 1,3-propanediol to solve the problem of more by-products in the preparation process of 1,3-propanediol in the prior art.

[0015] In order to achieve the above object, according to one aspect of the present application, a method for preparing 1,3-propanediol is provided, which comprises: subjecting a 3-hydroxypropionaldehyde aqueous solution to a first hydrogenation reaction in the presence of a first hydrogenation catalyst to obtain a first hydrogenation reaction product, the 3-hydroxypropionaldehyde aqueous solution comprising any one or more of 4-hetero-oxy heptanedial, 1,3-dioxane-2-ethanol, 5,6-dihydro-2H-pyran-3-carboxaldehyde and 3,4-dihydro-2H-pyran-2-carboxaldehyde; and subjecting the first hydrogenation reaction product to a second hydrogenation reaction in the presence of a second hydrogenation catalyst to obtain a 1,3-propanediol product.

[0016] Further, the 3-hydroxypropionaldehyde aqueous solution further comprises a polycondensation reaction product of any two or more of 5,6-dihydro-2H-pyran-3-carboxaldehyde, 3,4-dihydro-2H-pyran-2-carboxaldehyde and 3-hydroxypropionaldehyde, and / or a self-polymerization reaction product of any one of 5,6-dihydro-2H-pyran-3-carboxaldehyde and 3,4-dihydro-2H-pyran-2-carboxaldehyde;

[0017] Preferably, the 3-hydroxypropionaldehyde aqueous solution is a solution obtained by removing acrolein after subjecting acrolein to a hydration reaction with water;

[0018] Preferably, the mass fraction of 3-hydroxypropionaldehyde in the 3-hydroxypropionaldehyde aqueous solution is 5% to 40%,

[0019] Preferably, the mass fraction of 4-hetero-oxy heptanedial in the 3-hydroxypropionaldehyde aqueous solution is 0.1% to 2.2%,

[0020] Preferably, the mass fraction of 1,3-dioxane-2-ethanol in the 3-hydroxypropionaldehyde aqueous solution is 0.01% to 0.5%,

[0021] Preferably, the mass fraction of 5,6-dihydro-2H-pyran-3-carboxaldehyde in the 3-hydroxypropionaldehyde aqueous solution is 0.01% to 0.5%,

[0022] Preferably, the mass fraction of 3,4-dihydro-2H-pyran-2-carboxaldehyde in the 3-hydroxypropionaldehyde aqueous solution is 0.01% to 0.5%.

[0023] Further, the first hydrogenation catalyst is any one or more of a fixed-bed Raney nickel catalyst and a supported nickel catalyst;

[0024] Preferably, the nickel loading of the fixed-bed Raney nickel catalyst is 45wt% to 90wt%;

[0025] Preferably, the nickel loading of the supported nickel catalyst is 45wt% to 90wt%;

[0026] Preferably, the carrier of the nickel catalyst is any one or more of alumina, silica, silicon carbide and diatomite;

[0027] Preferably, the average particle size of the first-stage hydrogenation catalyst is 1-10 mm.

[0028] Further, the second-stage hydrogenation catalyst is an X / A supported catalyst, wherein X is an active metal and A is a carrier, the active metal is any one or more of Pt, Pd, Fe, Co, Mo, Cr, Zn and Ni, and the carrier is an acidic molecular sieve;

[0029] Preferably, the acidic molecular sieve is selected from any one or more of HZSM-5, Beta, Y molecular sieve and mordenite;

[0030] Preferably, the loading amount of the active metal is 0.1wt%-5wt%.

[0031] Further, the reactor for the first-stage hydrogenation reaction and / or the second-stage reaction is a fixed bed reactor.

[0032] Preferably, the reactor for the first-stage hydrogenation reaction and / or the second-stage reaction is a column reactor.

[0033] Further, the length-diameter ratio of the reactor for the first-stage hydrogenation reaction and / or the second-stage reaction is 10-100.

[0034] Further, the pressure of the first-stage hydrogenation reaction is 2-8 MPa and the temperature is 30-80℃.

[0035] Further, the mass space velocity of the 3-hydroxypropanal aqueous solution entering the reactor for the first-stage hydrogenation reaction is 0.1-10 h -1 ;

[0036] Preferably, the hydrogen / oil ratio of the first-stage hydrogenation reaction is 10-100.

[0037] Further, the pressure of the second-stage reaction is 2-8 MPa and the temperature is 200-300℃.

[0038] Preferably, the mass space velocity of the first-stage hydrogenation reaction product entering the reactor for the second-stage reaction is 0.2-10 h -1 .

[0039] According to another aspect of the present application, a 1,3-propanediol product is provided, which is prepared by any one of the above preparation methods, and preferably, the content of aldehyde in the 1,3-propanediol product is ≤10 ppm.

[0040] The technical scheme of the present application adopts two-stage hydrogenation, wherein in the second-stage reaction, high-temperature hydrogenation is used to fully hydrogenate the aldehyde raw material and impurities for the reaction by using the hydrogenation performance of the metal-loaded hydrogenation, and the molecular sieve carrier used has acid sites, which can hydrolyze the by-products generated by the hydration hydrogenation of propylene aldehyde, such as 4-hetero-oxy heptanediol and 1,3-dioxane-2-ethanol, to generate 1,3-propanediol, so that the yield of 1,3-propanediol can be increased by 3-6 percentage points, the economic efficiency of the propylene aldehyde hydration hydrogenation process is effectively improved, and the problem of the difficulty in treating and resource utilization of the impurities generated in the 1,3-propanediol production route of the propylene aldehyde hydration process is solved. BRIEF DESCRIPTION OF DRAWINGS

[0041] The drawings accompanying the specification of the present application form a part thereof, serve to provide further understanding of the present application, and together with the description of the present application, explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0042] Figure 1 A schematic diagram of a 1,3-propanediol preparation device according to Embodiment 1 of the present application is shown.

[0043] In the above drawings, the following reference signs are used: 1, 3-HPA aqueous solution feed pump; 2, hydrogen feed pump; 3, preheater; 4, first-stage fixed-bed reactor; 5, second-stage fixed-bed reactor; 6, condenser; 7, gas-liquid separator; 8, back pressure valve; 9, discharge valve; 10, hydrogen compressor. DETAILED DESCRIPTION

[0044] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0045] As analyzed in the background art of the present application, there are many by-products in the preparation process of 1,3-propanediol in the prior art, which leads to a low yield of the product and difficulty in separation. In order to solve this problem, the present application provides a preparation method and product of 1,3-propanediol.

[0046] According to a typical embodiment of the present application, a preparation method of 1,3-propanediol is provided, which comprises: subjecting 3-hydroxypropionaldehyde aqueous solution to a first-stage hydrogenation reaction under the action of a first-stage hydrogenation catalyst to obtain a first-stage hydrogenation reaction product, the 3-hydroxypropionaldehyde aqueous solution comprising any one or more of 4-hetero-oxy heptanediol, 1,3-dioxane-2-ethanol, 5,6-dihydro-2H-pyran-3-carboxaldehyde, and 3,4-dihydro-2H-pyran-2-carboxaldehyde; and subjecting the first-stage hydrogenation reaction product to a second-stage reaction under the action of a second-stage hydrogenation catalyst under hydrogen to obtain a 1,3-propanediol product.

[0047] The above preparation method adopts two-stage hydrogenation, and in the second-stage reaction, high-temperature hydrogenation is used to fully hydrogenate the aldehyde raw material and impurities of the reaction by using the hydrogenation performance of the metal-loaded hydrogenation, and the molecular sieve carrier used has acid sites, which can hydrolyze the by-products generated by the hydration hydrogenation of propylene aldehyde, such as 4-hetero-oxy heptanediol and 1,3-dioxane-2-ethanol, to generate 1,3-propanediol, so that the yield of 1,3-propanediol can be increased by 3-6 percentage points, the economic efficiency of the propylene aldehyde hydration hydrogenation process is effectively improved, and the problem of the impurities generated in the 1,3-propanediol production route of the propylene aldehyde hydration process being difficult to handle and resource utilization is solved.

[0048] In some embodiments of the present application, the aqueous 3-hydroxypropanal solution further comprises a polycondensation reaction product of any two or more of 5,6-dihydro-2H-pyran-3-carboxaldehyde, 3,4-dihydro-2H-pyran-2-carboxaldehyde and 3-hydroxypropanal, and / or a self-polymerization reaction product of any one of 5,6-dihydro-2H-pyran-3-carboxaldehyde and 3,4-dihydro-2H-pyran-2-carboxaldehyde, which can be hydrogenated in the second-stage reaction to reduce the aldehyde content in the product, further reduce the purification difficulty of 1,3-propanediol, and improve the product quality.

[0049] In some typical embodiments of the present application, in order to improve the reaction efficiency and the yield of the target product, and to simplify the process and reduce impurities, the above aqueous 3-hydroxypropanal solution is a solution obtained by removing propylene aldehyde after the hydration reaction of propylene aldehyde with water. Preferably, the mass fraction of 3-hydroxypropanal in the aqueous 3-hydroxypropanal solution is 5%-40%, which is beneficial to further improve the reaction efficiency and the product yield.

[0050] In some embodiments of the present application, the mass fraction of 4-hetero-oxy heptanediol in the aqueous 3-hydroxypropanal solution is 0.1%-2.2%, which can undergo hydrogenation reaction and hydrolysis reaction in the second-stage reaction process under the action of the second-stage hydrogenation catalyst by the method of the present application, i.e., hydrogenation is first converted into 4-hetero-oxy heptanediol, and further hydrolysis generates 1,3-propanediol, which has high selectivity and conversion rate.

[0051] In some embodiments of the present application, the mass fraction of 1,3-dioxane-2-ethanol in the aqueous 3-hydroxypropanal solution is 0.01%-0.5%, which can also be efficiently converted into 1,3-propanediol in the second-stage reaction process under the conditions of the present application.

[0052] In some embodiments of the present application, the mass fraction of 5,6-dihydro-2H-pyran-3-carboxaldehyde in the aqueous 3-hydroxypropanal solution is 0.01%-0.5%, which can undergo hydrogenation reaction in the second-stage reaction to reduce the aldehyde content in the product and improve the product quality.

[0053] In some embodiments of the present application, the mass fraction of 3,4-dihydro-2H-pyran-2-carboxaldehyde in the aqueous 3-hydroxypropanal solution is 0.01%-0.5%, which can reduce the aldehyde content in the product and improve the product quality in the second-stage reaction.

[0054] The first-stage hydrogenation catalyst can be selected from the existing catalysts used in the hydrogenation reaction of 3-hydroxypropanal. In some preferred embodiments of the present application, the first-stage hydrogenation catalyst is any one or more of a fixed-bed Raney nickel catalyst and a supported nickel catalyst, which has good selectivity, a relatively wide range of requirements for reaction conditions, and produces less impurities that cannot be converted into 1,3-propanediol. In order to further improve the catalytic efficiency, the average particle size of the first-stage hydrogenation catalyst is preferably 1-10 mm.

[0055] Preferably, the nickel loading of the fixed-bed Raney nickel catalyst is 45wt%-90wt%, and the nickel loading of the supported nickel catalyst is 45wt%-90wt%, which significantly improves the catalytic effect on the hydrogenation reaction of 3-hydroxypropanal in the present application. The support of the supported nickel catalyst can be selected from the prior art. In some preferred embodiments of the present application, the support of the supported nickel catalyst is any one or more of alumina, silica, silicon carbide, and diatomite, which is beneficial to further improve the selectivity of the hydrogenation reaction of 3-hydroxypropanal.

[0056] In some typical embodiments of the present application, the second-stage hydrogenation catalyst is an X / A supported catalyst, wherein X is an active metal and A is a support. The active metal is any one or more of Pt, Pd, Fe, Co, Mo, Cr, Zn, and Ni, and the support is an acidic molecular sieve. This second-stage hydrogenation catalyst not only converts the remaining 3-hydroxypropanal in the system into 1,3-propanediol, 4-hetero-oxyheptanediol into 4-hetero-oxyheptanediol, 5,6-dihydro-2H-pyran-3-carboxaldehyde into 3-hydroxymethyltetrahydropyran, and 3,4-dihydro-2H-pyran-2-carboxaldehyde into 2-hydroxymethyltetrahydropyran, but also has good catalytic effect on the ether bond hydrolysis of 4-hetero-oxyheptanediol and 1,3-dioxane-2-ethanol in the system to generate 1,3-propanediol, thereby further improving the yield of 1,3-propanediol.

[0057] The reaction equation of the main reaction occurring in the second-stage reaction is as follows:

[0058]

[0059] The preparation method of the X / A supported catalyst has no particular requirements, and those skilled in the art can prepare the X / A supported catalyst according to the method in the prior art. Exemplarily, the X / A supported catalyst is prepared by an impregnation method, and the preparation process is as follows: a water-soluble salt solution of an active component is added into a molecular sieve carrier according to a metering ratio for impregnation, and then dried and calcined into a metal oxide form, and the catalyst needs to be reduced in hydrogen before use.

[0060] The acid-washed molecular sieve can be selected from the prior art, and in some preferred embodiments of the present application, the acid molecular sieve is selected from any one or more of HZSM-5, Beta, Y molecular sieve and mordenite, which has a relatively significant effect on improving the yield of 1,3-propanediol. Preferably, the loading amount of the active metal is 0.1wt%-5wt%, which has a relatively significant effect on promoting the hydrolysis of 4-hetero-oxy heptanediol and 1,3-dioxane-2-ethanol to generate 1,3-propanediol.

[0061] In order to better play the role of the first-stage hydrogenation catalyst and / or the second-stage hydrogenation catalyst and further improve the yield of 1,3-propanediol, the reactor for the first-stage hydrogenation reaction and / or the second-stage reaction is a fixed bed reactor.

[0062] In some typical embodiments of the present application, the reactor for the first-stage hydrogenation reaction and / or the second-stage reaction is a column reactor, which has good heat exchange and mixing effects, is conducive to improving the reaction rate and reducing the energy consumption of the reaction.

[0063] Since the aspect ratio of the reactor affects the contact, mass transfer and heat exchange of the catalyst with the reaction liquid and hydrogen, and further affects the reaction process, in some preferred embodiments of the present application, the aspect ratio of the reactor for the first-stage hydrogenation reaction and / or the second-stage reaction is 10-100; within this range, the catalyst loading is considered, which is helpful for the heat exchange of the reactor, ensures uniform temperature control during the reaction process, and avoids hot spots, and at the same time, it is helpful for the full contact of the catalyst with the reaction material, reduces the influence of channeling, and improves the reaction effect.

[0064] In some typical embodiments of the present application, the pressure of the first-stage hydrogenation reaction is 2-8 MPa, and the temperature is 30-80°C, that is, the good selectivity and conversion rate of 3-hydroxypropanal are realized at a relatively low temperature and pressure.

[0065] In order to further improve the catalytic efficiency of the first-stage hydrogenation catalyst, the mass space velocity of the 3-hydroxypropanal aqueous solution entering the reactor for the first-stage hydrogenation reaction is 0.1-10 h -1In some preferred embodiments of the present application, the hydrogen oil ratio in the first hydrogenation reaction is 10-100, i.e. the molar ratio of hydrogen gas to 3-hydroxypropanal in the 3-hydroxypropanal aqueous solution is 10-100:1.

[0066] In some embodiments of the present application, the conversion rate of the raw material 3-hydroxypropanal in the first hydrogenation reaction is above 95%.

[0067] In some embodiments of the present application, the pressure in the second reaction is 2-8 MPa and the temperature is 200-300°C. Under such conditions, the remaining 3-hydroxypropanal in the system can be fully converted into 1,3-propanediol, and the 4-hetero-oxy heptanediol and 1,3-dioxane-2-ethanol in the system can also be efficiently hydrolyzed under the action of the catalyst to generate 1,3-propanediol.

[0068] In some typical embodiments of the present application, in order to simplify the process, the post-reaction material of the first hydrogenation reaction, including the gaseous material and the liquid material, is directly introduced into the reactor for the second reaction. In some embodiments of the present application, in order to improve the efficiency of the second reaction, the mass space velocity of the first hydrogenation reaction product into the reactor for the second reaction is 0.2-10 h -1 .

[0069] In some typical embodiments of the present application, after the second reaction, the conversion rate of 3-HPA is >99.9%, the conversion rate of 4-hetero-oxy heptanediol is >80%, and the conversion rate of 1,3-dioxane-2-ethanol is >90%.

[0070] In some typical embodiments of the present application, through the above preparation method, not only the conversion rate of 3-hydroxypropanal is above 99.9%, but also other macromolecular aldehyde impurities generated by hydration are fully hydrogenated, and the hydrogenated liquid aldehyde content is <10 ppm, which reduces the difficulty of separation of PDO and improves the product quality of PDO. The content of the finally separated 1,3-PDO can be above 99.98%.

[0071] According to another typical embodiment of the present application, a 1,3-propanediol product is provided, which is prepared by any one of the above preparation methods. The 1,3-propanediol product of the present application is obtained by the above preparation method, has a high conversion rate, and thus has a low cost. In addition, the aldehyde impurities are fully hydrogenated, and the 4-hetero-oxy heptanediol and 1,3-dioxane-2-ethanol in the 3-hydroxypropanal aqueous solution are hydrolyzed and converted into the product, which has a high purity and is convenient for subsequent separation and purification.

[0072] The beneficial effects that can be achieved by the present application will be further illustrated below with reference to examples and comparative examples.

[0073] In each embodiment:

[0074] 3-hydroxypropanal conversion rate / % = the number of moles of 3-hydroxypropanal converted in the reaction / the number of moles of 3-hydroxypropanal entering the reactor x 100%;

[0075] 1,3-PDO yield / % = (the number of moles of 1,3-propanediol in the product / the number of moles of 3-hydroxypropanal entering the reactor) x 100%;

[0076] 5,6-dihydro-2H-pyran-3-carboxaldehyde conversion rate / % = [1- (5,6-dihydro-2H-pyran-3-carboxaldehyde content in the second-stage reaction liquid x the mass of the reaction liquid) / (5,6-dihydro-2H-pyran-3-carboxaldehyde in the raw material x the mass of the raw material)] x 100%;

[0077] 3,4-dihydro-2H-pyran-2-carboxaldehyde conversion rate / % = [1- (3,4-dihydro-2H-pyran-2-carboxaldehyde content in the second-stage reaction liquid x the mass of the reaction liquid) / (3,4-dihydro-2H-pyran-2-carboxaldehyde in the raw material x the mass of the raw material)] x 100%;

[0078] 4-hetero-oxy heptanediol conversion rate / % = [(4-hetero-oxy heptanediol content in the raw material x the mass of the raw material) / 130- (4-hetero-oxy heptanediol in the second-stage reaction liquid x the mass of the reaction liquid) / 134] / (4-hetero-oxy heptanediol content in the raw material x the mass of the raw material / 130) x 100% (there is no 4-hetero-oxy heptanediol in the raw material, 4-hetero-oxy heptanediol is generated from 100% conversion of 4-hetero-oxy heptanediol, and 1,3-propanediol is generated from hydrolysis during hydrogenation conversion, therefore the content in the raw material is calculated based on 4-hetero-oxy heptanediol in the conversion rate);

[0079] 1,3-dioxane-2-ethanol conversion rate / % = [1- (1,3-dioxane-2-ethanol content in the second-stage reaction liquid x the mass of the reaction liquid) / (1,3-dioxane-2-ethanol content in the raw material x the mass of the raw material)] x 100%;

[0080] Gas chromatography quantitative analysis method: gas chromatography internal standard quantitative method is used to analyze the content of each component, the specific method is as follows: about 1 g (accurate to 0.0001 g) of the liquid to be measured is weighed using an analytical balance, 0.2 g (accurate to 0.0001 g) of internal standard isopropanol is added, and the solvent acetonitrile is diluted to 8 mL, then 1 mL is taken and placed in a chromatographic sample bottle, and an Agilent 7890B gas chromatograph is used for quantitative analysis, the chromatographic column is a wax column, the sample size is 0.4 microliters, after the sample injection is completed, the content of each component is calculated according to the correction factor and the peak area; each sample is tested twice according to the above method, and the quantitative results are taken as the average of the two analysis results to calculate the conversion rate and selectivity.

[0081] The percentage in the following examples is mass percentage, unless otherwise specified.

[0082] The first fixed bed catalyst is commercially available, and the second fixed bed catalyst is prepared by impregnation method, and the preparation method is as follows:

[0083] The water solution of soluble salt of active component is added into the molecular sieve carrier according to the metering ratio for impregnation, and then dried and calcined into metal oxide form. The catalyst needs to be reduced in hydrogen before use, and the reduction conditions are hydrogen pressure of 3 MPa, hydrogen space velocity of 500 h -1 -1, reduction temperature of 300 DEG C, and reduction time of 16 hours.

[0084] Example 1

[0085] This example uses the device as shown in Figure 1 to prepare 1,3-propanediol.

[0086] After the hydration reaction, 8.5% of 3-hydroxypropionaldehyde aqueous solution (i.e. raw material, same below) is removed from propylene aldehyde, 4-hetero-oxy heptanedialdehyde content is 0.5%, 1,3-dioxane-2-ethanol content is 0.15%, 5,6-dihydro-2H-pyran-3-methanal content is 0.07%, and 3,4-dihydro-2H-pyran-2-methanal is 0.1%, with mass space velocity of 1.0 h -1 After being preheated by preheater 3, the 3-HPA aqueous solution is pumped into the first fixed bed reactor 4; at the same time, hydrogen is pumped into the first fixed bed reactor 4 by hydrogen feeding pump 2 through preheater 3, the length-diameter ratio of the first fixed bed reactor 4 is 20, and it is filled with fixed bed Raney nickel (nickel loading of 45%), the first reaction temperature is controlled at 50 DEG C, the hydrogen pressure is 4 MPa, and the hydrogen / 3-hydroxypropionaldehyde molar ratio is 30.

[0087] After the first reaction is completed, the conversion rate of 3-hydroxypropionaldehyde is 99.2%, and the yield of 1,3-PDO is 98.7%.

[0088] The reaction liquid and gas in the first fixed bed reactor 4 are pumped into the second fixed bed reactor 5 with length-diameter ratio of 10 and filled with Ni / HZSM-5 (nickel loading of 5%) at mass space velocity of 2.0 h -1 , the second reaction temperature is controlled at 220 DEG C, and the back pressure valve 8 is adjusted to make the reaction pressure 4 MPa. The reaction liquid of the second reaction is sent into the condenser 6 for condensation to 35 DEG C, and then separated into hydrogen in the gas-liquid separator 7, the separated hydrogen is pressurized by hydrogen compressor 10, and then preheated by preheater 3 again before being pumped into the first fixed bed reactor 4; the liquid components in the gas-liquid separator 7 are discharged through the discharge valve 9, and then subjected to gas chromatography internal standard quantitative test and subsequent purification treatment.

[0089] After the completion of the second-stage reaction, the conversion rate of 3-hydroxypropanal was 100%, the conversion rate of 4-hexyloxyheptanediol was 85%, the conversion rate of 1,3-dioxane-2-ethanol was 91%, the conversion rate of 5,6-dihydro-2H-pyran-3-carbaldehyde was 99.8%, the conversion rate of 3,4-dihydro-2H-pyran-2-carbaldehyde was 99.1%, and the yield of 1,3-PDO was 104.5% (calculated based on the molar number of 3-hydroxypropanal). The reaction liquid of the second-stage reaction was separated by dehydration, removal of light components, removal of heavy components and rectification to obtain a 1,3-PDO product with a purity of 99.990%.

[0090] Example 2

[0091] The 38% 3-hydroxypropanal aqueous solution from which acrolein was removed after hydration reaction had a 4-heterooxyheptanedial content of 2.2%, a 1,3-dioxane-2-ethanol content of 0.31%, a 5,6-dihydro-2H-pyran-3-carboxaldehyde content of 0.18%, and a 3,4-dihydro-2H-pyran-2-carboxaldehyde content of 0.24%. -1 , pumped into a reactor with a length-to-diameter ratio of 80 and filled with fixed-bed Raney nickel (nickel loading 60%), controlling the reaction temperature at 45°C, the hydrogen pressure at 5 MPa, and the hydrogen / 3-hydroxypropionaldehyde molar ratio at 70.

[0092] After the first stage of reaction, the conversion rate of 3-hydroxypropanal was 98.5% and the yield of 1,3-PDO was 96.7%.

[0093] Then the reaction liquid and gas in a fixed bed are fed at a mass space velocity of 1.0h -1 , pumped into a two-stage fixed-bed reactor with a length-to-diameter ratio of 60 and loaded with Pd / Beta (Pd loading 1%), and the second-stage reaction temperature was controlled at 250°C and the reaction pressure was 5 MPa.

[0094] After the reaction, the conversion rate of 3-hydroxypropanal was 99.98%, the conversion rate of 4-hexyloxyheptanediol was 89%, the conversion rate of 1,3-dioxane-2-ethanol was 96%, the conversion rate of 5,6-dihydro-2H-pyran-3-carbaldehyde was 99.9%, the conversion rate of 3,4-dihydro-2H-pyran-2-carbaldehyde was 99.5%, and the yield of 1,3-PDO was 105.1% (calculated based on the molar number of 3-hydroxypropanal). After separation using the same method as in Example 1, the purity of 1,3-PDO was 99.990%.

[0095] Example 3

[0096] A 5.5% aqueous solution of 3-hydroxypropanal after removal of propenal, 4-oxoheptandial content 0.1%, 1,3-dioxan-2-ethanol content 0.03%, 5,6-dihydro-2H-pyran-3-carboxaldehyde content 0.02%, 3,4-dihydro-2H-pyran-2-carboxaldehyde 0.4%, was pumped at a mass hourly space velocity of 8 h -1 into a first reactor having a length to diameter ratio of 50 packed with nickel / alumina (nickel loading 50%) and the reaction temperature was controlled at 60°C, the hydrogen pressure was 5.5 MPa and the hydrogen / 3-hydroxypropanal molar ratio was 7.

[0097] After completion of the first stage reaction, the conversion of 3-hydroxypropanal was 99.6% and the yield of 1,3-PDO was 98.4%.

[0098] The reaction liquid and gas in the first fixed bed was then pumped at a mass hourly space velocity of 4.0 h -1 into a second fixed bed reactor having a length to diameter ratio of 30 packed with Pt / Y molecular sieve (Pd loading 0.5%) and the second stage reaction temperature was controlled at 260°C and the reaction pressure was 5.5 MPa.

[0099] After completion of the reaction, the conversion of 3-hydroxypropanal was 99.96%, the conversion of 4-oxoheptandial was 93%, the conversion of 1,3-dioxan-2-ethanol was 95%, the conversion of 5,6-dihydro-2H-pyran-3-carboxaldehyde was 99.9%, the conversion of 3,4-dihydro-2H-pyran-2-carboxaldehyde was 99.9% and the yield of 1,3-PDO was 104.1% (calculated on the moles of 3-hydroxypropanal). After separation in the same manner as in Example 1, the purity of 1,3-PDO was 99.995%.

[0100] Example 4

[0101] A 12% aqueous solution of 3-hydroxypropanal after removal of propenal, 4-oxoheptandial content 0.4%, 1,3-dioxan-2-ethanol content 0.13%, 5,6-dihydro-2H-pyran-3-carboxaldehyde content 0.20%, 3,4-dihydro-2H-pyran-2-carboxaldehyde 0.21%, was pumped at a mass hourly space velocity of 4 h -1 into a first reactor having a length to diameter ratio of 30 packed with nickel / silicon carbide (nickel loading 45%) and the reaction temperature was controlled at 55°C, the hydrogen pressure was 6 MPa and the hydrogen / 3-hydroxypropanal molar ratio was 15.

[0102] After completion of the first stage reaction, the conversion of 3-hydroxypropanal was 99.1% and the yield of 1,3-PDO was 98.5%.

[0103] The reaction liquid and gas in the first fixed bed was then pumped at a mass hourly space velocity of 5 h -1, pumped into a second-stage fixed-bed reactor with a length-to-diameter ratio of 20 and loaded with Ni-Cr / mordenite (Ni loading 0.2%, Cr loading 0.5%), and the second-stage reaction temperature was controlled at 210°C and the reaction pressure was 6 MPa.

[0104] After the reaction, the conversion rate of 3-hydroxypropanal, the conversion rate of 4-heterooxyheptanediol, the conversion rate of 1,3-dioxane-2-ethanol, the conversion rate of 5,6-dihydro-2H-pyran-3-carbaldehyde, the conversion rate of 3,4-dihydro-2H-pyran-2-carbaldehyde, and the yield of 1,3-PDO were 103.1% (calculated based on the molar number of 3-hydroxypropanal). After separation in the same manner as in Example 1, the purity of 1,3-PDO was 99.982%.

[0105] Example 5

[0106] The difference from Example 1 is that the hydrogen pressure in the first stage reaction is 3 MPa. After the first stage reaction, the conversion rate of 3-hydroxypropanal is 99.0%, and the yield of 1,3-PDO is 98.5%.

[0107] After the completion of the second stage reaction, the conversion rate of 3-hydroxypropanal was 100%, the conversion rate of 4-hexyloxyheptanediol was 84.5%, the conversion rate of 1,3-dioxane-2-ethanol was 90.1%, the conversion rate of 5,6-dihydro-2H-pyran-3-carbaldehyde was 99.3%, the conversion rate of 3,4-dihydro-2H-pyran-2-carbaldehyde was 99.0%, the yield of 1,3-PDO was 104.0% (calculated based on the molar number of 3-hydroxypropanal), and the purity of 1,3-PDO after separation was 99.982%.

[0108] Example 6

[0109] The difference from Example 1 is that the hydrogen pressure in the first stage reaction is 2 MPa. After the first stage reaction, the conversion rate of 3-hydroxypropanal is 98.5%, and the yield of 1,3-PDO is 96.5%.

[0110] After the completion of the second stage reaction, the conversion rate of 3-hydroxypropanal, 4-hexyloxyheptanediol, 1,3-dioxane-2-ethanol, 5,6-dihydro-2H-pyran-3-carbaldehyde, 3,4-dihydro-2H-pyran-2-carbaldehyde, and 1,3-PDO were 99.980% (calculated based on the molar number of 3-hydroxypropanal).

[0111] Example 7

[0112] The difference from Example 1 is that the catalyst packed in the first reactor is 55% Ni / Al2O3. After the first reaction, the conversion of 3-hydroxypropanal is 98.9%, and the yield of 1,3-PDO is 98.4%.

[0113] After the second reaction, the conversion of 3-hydroxypropanal is 100%, the conversion of 4-oxapentanediol is 84.8%, the conversion of 1,3-dioxan-2-ethanol is 90.8%, the conversion of 5,6-dihydro-2H-pyran-3-carbaldehyde is 99.7%, the conversion of 3,4-dihydro-2H-pyran-2-carbaldehyde is 99.5%, and the yield of 1,3-PDO is 104.0% (calculated based on the moles of 3-hydroxypropanal), and the purity of 1,3-PDO after separation is 99.984%.

[0114] Example 8

[0115] The difference from Example 1 is that the temperature of the second reaction is 160°C. After the second reaction, the conversion of 3-hydroxypropanal is 99.9%, the conversion of 4-oxapentanediol is 75.3%, the conversion of 1,3-dioxan-2-ethanol is 87.5%, the conversion of 5,6-dihydro-2H-pyran-3-carbaldehyde is 93.5%, the conversion of 3,4-dihydro-2H-pyran-2-carbaldehyde is 92.3%, the yield of 1,3-PDO is 102.0% (calculated based on the moles of 3-hydroxypropanal), and the purity of 1,3-PDO after separation is 99.981%.

[0116] Example 9

[0117] The difference from Example 1 is that the catalyst packed in the second reactor is Pt / ZSM-5 molecular sieve (Pt loading 1%). After the second reaction, the conversion of 3-hydroxypropanal is 99.8%, the conversion of 4-oxapentanediol is 9.8%, the conversion of 1,3-dioxan-2-ethanol is 82.3%, the conversion of 5,6-dihydro-2H-pyran-3-carbaldehyde is 70.3%, the conversion of 3,4-dihydro-2H-pyran-2-carbaldehyde is 65.3%, the yield of 1,3-PDO is 100.1% (calculated based on the moles of 3-hydroxypropanal), and the purity of 1,3-PDO after separation is 99.90%.

[0118] Comparative Example 1

[0119] 8.5% of the 3-hydroxypropanal aqueous solution after the hydration reaction was removed, and the 3-hydroxypropanal aqueous solution was pumped into the first reactor with a length-diameter ratio of 20, packed with 22% Ni-12% Mo-2.5% Co / Al2O3, and the reaction temperature was controlled at 50°C, the hydrogen pressure was 5 MPa, and the hydrogen / 3-hydroxypropanal molar ratio was 50. -1

[0120] ​The conversion rate of 3-hydroxypropanal is 92.1% after the first reaction.

[0121] The first fixed bed reaction liquid is continuously subjected to the second hydrogenation reaction, the reaction temperature is 120 DEG C, the hydrogen pressure is 5 MPa, the mass space velocity of 3-hydroxypropanal aqueous solution is 2.0 h-1, and the hydrogen / 3-hydroxypropanal molar ratio is 10. -1

[0122] The conversion rate of 3-hydroxypropanal is 99.9% after the second reaction, the yield of 1,3-PDO is 99.8%, and the purity of 1,3-PDO after separation is 99.7%.

[0123] From the above description, it can be seen that the above-mentioned embodiments of the present application achieve the following technical effects: two-stage hydrogenation is adopted, in which, in the second reaction, high-temperature hydrogenation is used, which not only utilizes the hydrogenation performance of the supported metal to fully hydrogenate the aldehyde raw material and impurities for the reaction, but also uses the molecular sieve carrier with acid sites to hydrolyze the ether bond of the by-products 4-hetero-oxy heptanediol and 1,3-dioxane-2-ethanol generated by the hydration of propylene aldehyde to generate 1,3-propanediol, so that the yield of 1,3-propanediol can be increased by 3-6 percentage points, effectively improving the economic efficiency of the propylene aldehyde hydration hydrogenation process, and solving the problems of difficult treatment and resource utilization of the impurities generated in the 1,3-propanediol production process of the propylene aldehyde hydration process.

[0124] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.​

Claims

1. A method for preparing 1,3-propylene glycol, characterized in that: include: A 3-hydroxypropanal aqueous solution is subjected to a first-stage hydrogenation reaction under the action of a first-stage hydrogenation catalyst to obtain a first-stage hydrogenation reaction product, wherein the 3-hydroxypropanal aqueous solution comprises any one or more of 4-heterooxyheptanedial, 1,3-dioxane-2-ethanol, 5,6-dihydro-2H-pyran-3-carboxaldehyde, and 3,4-dihydro-2H-pyran-2-carboxaldehyde; and the first-stage hydrogenation catalyst is any one or more of a fixed-bed Raney nickel catalyst and a supported nickel catalyst; The product of the first-stage hydrogenation reaction is subjected to a second-stage reaction under the action of a second-stage hydrogenation catalyst to obtain a 1,3-propylene glycol product; the second-stage hydrogenation catalyst is an X / A supported catalyst, wherein X is an active metal, A is a carrier, the active metal is any one or more of Pt, Pd and Ni, and the carrier is an acidic molecular sieve; the pressure of the second-stage reaction is 2-8 MPa, and the temperature is 200-300°C.

2. The preparation method according to claim 1, characterized in that The 3-hydroxypropionaldehyde aqueous solution also includes condensation reaction products of any two or more of 5,6-dihydro-2H-pyran-3-carboxaldehyde, 3,4-dihydro-2H-pyran-2-carboxaldehyde and 3-hydroxypropionaldehyde, and / or a self-polymerization reaction product of any one of 5,6-dihydro-2H-pyran-3-carboxaldehyde and 3,4-dihydro-2H-pyran-2-carboxaldehyde.

3. The preparation method according to claim 2, characterized in that The 3-hydroxypropionaldehyde aqueous solution is a solution obtained by removing acrolein after acrolein undergoes a hydration reaction with water.

4. The preparation method according to claim 2, characterized in that The mass fraction of 3-hydroxypropionaldehyde in the 3-hydroxypropionaldehyde aqueous solution is 5%-40%; and / or, the mass fraction of the 4-heterooxyheptanedial in the 3-hydroxypropanal aqueous solution is 0.1%-2.2%, and / or, the mass fraction of 1,3-dioxane-2-ethanol in the 3-hydroxypropionaldehyde aqueous solution is 0.01%-0.5%, and / or, the mass fraction of the 5,6-dihydro-2H-pyran-3-carbaldehyde in the 3-hydroxypropionaldehyde aqueous solution is 0.01%-0.5%, And / or, the mass fraction of the 3,4-dihydro-2H-pyran-2-carbaldehyde in the 3-hydroxypropionaldehyde aqueous solution is 0.01%-0.5%.

5. The preparation method according to claim 1, characterized in that The nickel loading amount of the fixed-bed Raney nickel catalyst is 45 wt % to 90 wt %.

6. The preparation method according to claim 1, characterized in that The nickel loading amount of the supported nickel catalyst is 45 wt % to 90 wt %.

7. The preparation method according to claim 1, characterized in that The carrier of the nickel-loaded catalyst is any one or more of alumina, silicon dioxide, silicon carbide and diatomaceous earth.

8. The preparation method according to claim 1, characterized in that The average particle size of the first stage hydrogenation catalyst is 1-10 mm.

9. The preparation method according to claim 1, characterized in that The acidic molecular sieve is selected from any one or more of HZSM-5, Beta, Y molecular sieve and mordenite.

10. The preparation method according to claim 1, characterized in that The loading amount of the active metal is 0.1 wt%-5 wt%.

11. The preparation method according to claim 1, characterized in that The reactor for the first-stage hydrogenation reaction and / or the second-stage reaction is a fixed bed reactor.

12. The preparation method according to claim 11, characterized in that The reactor for the first-stage hydrogenation reaction and / or the second-stage reaction is a shell-and-tube reactor.

13. The preparation method according to claim 11, characterized in that The length-to-diameter ratio of the reactor for the first-stage hydrogenation reaction and / or the second-stage reaction is 10-100.

14. The preparation method according to any one of claims 1 to 13, characterized in that The pressure of the first stage hydrogenation reaction is 2-8 MPa and the temperature is 30-80°C.

15. The preparation method according to any one of claims 1 to 13, characterized in that: The mass space velocity of the 3-hydroxypropanal aqueous solution entering the reactor of the first stage hydrogenation reaction is 0.1-10h -1 .

16. The preparation method according to claim 15, characterized in that The hydrogen-to-oil ratio of the one-stage hydrogenation reaction is 10-100.

17. The preparation method according to any one of claims 1 to 13, characterized in that: The mass space velocity of the first stage hydrogenation product entering the second stage reactor is 0.2-10h -1 .

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