Catalyst, process for its preparation and process for the hydrofinishing of recovered solvents of olefin epoxidation reactions

Abstract

The present application relates to the field of catalysis, discloses a catalyst, a preparation method thereof and a method for hydrofining of recovered solvent of olefin epoxidation reaction, the catalyst comprises a carrier and an active component supported on the carrier, the active component is Ni and Cu; wherein, the molar ratio of Ni and Cu in the catalyst is 0.5-5:1. The recovered solvent of olefin epoxidation reaction is hydrofined by using the catalyst, and acetaldehyde, hydrogen peroxide in the recovered solvent can be basically removed, and part of dimethoxyethane can be removed, so that the purpose of refining the recovered solvent is achieved. And more than 15% of steam energy consumption can be saved per year. In addition, the circulation and accumulation of dimethoxyethane in the solvent system of the device is avoided, the amount of fresh methanol supplemented for replacing dimethoxyethane is greatly reduced, and more than 50% of the original methanol consumption can be saved per year.

Description

Technical Field

[0001] This invention relates to the field of catalysis, specifically to catalysts and their preparation methods, and to a method for hydrogenating and refining recovered solvents in olefin epoxidation reactions. Background Technology

[0002] The HPPO process (direct oxidation of propylene to propylene oxide using hydrogen peroxide as a raw material) produces propylene oxide using hydrogen peroxide as the oxidant and methanol as the solvent. Propylene is epoxidized via a titanium-silicon molecular sieve catalyst. During the olefin epoxidation reaction, impurities such as aldehydes, ketones, esters, and ethers are produced as byproducts, and trace amounts of hydrogen peroxide remain in the solvent. During the alcohol solvent distillation recovery stage, unreacted hydrogen peroxide and organic peroxide compounds oxidize the solvent and other substances, producing impurities such as acetals. Some of these impurities, such as formaldehyde, acetaldehyde, propionaldehyde, dimethoxymethane, and dimethoxyethane, are difficult to separate from the alcohol solvent and the product propylene oxide through distillation. This leads to a decrease in the purity of the recycled alcohol solvent and an increase in impurities in the product propylene oxide, thus affecting product purity. Furthermore, dimethoxyethane accumulates in the system with the circulating solvent and can only be replaced periodically with a certain amount of fresh methanol. Simultaneously, the accumulation of these impurities also has a detrimental effect on the activity of the epoxidation catalyst. Furthermore, the current HPPO unit's circulating solvent hydrogenation mainly targets the alcohol-water mixture produced by the epoxidation reaction product separation unit. The hydrogenated product still needs to be separated by distillation before the alcohol solvent can be recycled. The energy consumption of the alcohol solvent distillation separation section accounts for more than 80% of the total energy consumption of the entire unit. Summary of the Invention

[0003] The purpose of this invention is to overcome the technical problems existing in the prior art, such as the high amount of impurities in the recovered solvent of olefin epoxidation reaction, the high consumption of fresh solvent, and the high energy consumption of subsequent processing, and to provide a catalyst suitable for the hydrogenation purification of recovered solvent in olefin epoxidation reaction, as well as its preparation method and the method for hydrogenation purification of recovered solvent in olefin epoxidation reaction.

[0004] To achieve the above objectives, a first aspect of the present invention provides a catalyst comprising a support and an active component supported on the support, wherein the active component is Ni and Cu;

[0005] In the catalyst, the molar ratio of Ni to Cu is 0.5-10:1.

[0006] A second aspect of the present invention provides a method for preparing a catalyst, the method comprising:

[0007] The active components are loaded onto a support, wherein the active components are Ni and Cu; and the molar ratio of Ni to Cu is 0.5-10:1.

[0008] A third aspect of the present invention provides a catalyst prepared by the method described above.

[0009] A fourth aspect of the present invention provides a method for hydrogenating and refining a recovered solvent in an olefin epoxidation reaction, the method comprising:

[0010] (1) In a hydrogen atmosphere, the recovered solvent from the olefin epoxidation reaction is brought into contact with the catalyst;

[0011] (2) Optionally, the effluent obtained after contact in step (1) can be used as a solvent for the olefin epoxidation reaction;

[0012] The catalyst in step (1) is the catalyst described above.

[0013] The catalyst of this invention is particularly suitable for the hydrorefining of recovered solvents in olefin epoxidation reactions. The method for hydrorefining recovered solvents in olefin epoxidation reactions provided by this invention, using the catalyst of this application, can substantially remove acetaldehyde and partially remove dimethoxyethane from the recovered solvent, achieving the purpose of refining the recovered solvent. Furthermore, the hydrorefined solvent is used as a circulating solvent, avoiding its entry into the high-temperature distillation column. Compared with conventional processes, this hydrorefining method can save more than 15% of steam energy consumption annually. In addition, it avoids the circulating accumulation of dimethoxyethane in the solvent system, significantly reducing the amount of fresh methanol needed to replace dimethoxyethane, saving more than 50% of the original methanol consumption annually.

[0014] In summary, the use of the catalyst of the present invention for the hydrogenation purification of recovered solvents in olefin epoxidation reactions has the following advantages:

[0015] (1) The solvent separated from the epoxide is hydrogenated and purified. This process is simple, mild, technologically advanced, and has low investment costs. After it is put into use, it will be of great significance for further improving the quality of the epoxide.

[0016] (2) The energy saving and consumption reduction effect is significant after adopting the hydrogenation refining method of the present invention. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a system for hydrogenation purification of recovered solvent in an olefin epoxidation reaction according to one embodiment of the present invention.

[0018] Explanation of reference numerals in the attached figures

[0019] 100 Conveying equipment, 200 First heat exchanger, 300 Second heat exchanger, 400 Mixing equipment, 500 Reaction equipment, 600 Third heat exchanger, 700 Separation equipment Detailed Implementation

[0020] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0021] A first aspect of the present invention provides a catalyst comprising a support and an active component supported on the support, wherein the active component is Ni and Cu;

[0022] In the catalyst, the molar ratio of Ni to Cu is 0.5-10:1, preferably 5-10:1.

[0023] In some embodiments of the present invention, the content of the active component, calculated as metal element, is 10-70% by weight, preferably 30-60% by weight, based on the total weight of the catalyst.

[0024] In some embodiments of the present invention, the specific surface area, pore volume, and pore size of the supported catalyst can be measured by nitrogen adsorption, the specific surface area is calculated using the BET method, and the pore volume is calculated using the BJH model. The specific surface area of ​​the catalyst is 80-200 m². 2 / g, preferably 120-170m 2 / g, more preferably 130-150m 2 / g. The pore volume of the catalyst is preferably 0.2-0.6 cm³. 3 / g, more preferably 0.25-0.5cm 3 / g. The average pore size of the catalyst is 2-10 nm, preferably 4-8 nm, and more preferably 5-7 nm.

[0025] In some embodiments of the present invention, to prevent copper microcrystal sintering, promote copper dispersion, and improve catalyst stability, the catalyst further includes a first promoter and / or a second promoter supported on the support, wherein the first promoter and the second promoter are selected from different transition metals. Preferably, the first promoter includes W and / or Mo. The second promoter includes Fe and / or Co.

[0026] In some embodiments of the present invention, in order to provide an effective surface and a suitable pore structure, maintain a high degree of dispersion of the active component, and enhance the mechanical strength of the catalyst, the support is selected from alumina and / or silica, preferably γ-Al2O3;

[0027] In some embodiments of the present invention, in order to ensure the hydrogenation activity of the catalyst, the content of the active component, calculated by metal element, is preferably 10-70% by weight, more preferably 30-60% by weight, based on the total weight of the catalyst; the content of the first auxiliary agent, calculated by metal element, is preferably 0-5% by weight, more preferably 1-2% by weight; the content of the second auxiliary agent, calculated by metal element, is 0-5% by weight, preferably 0.5-2% by weight, with the remainder being the carrier.

[0028] In some embodiments of the present invention, the active component and the auxiliary agent exist in an oxidized state.

[0029] A second aspect of the present invention provides a method for preparing a catalyst, the method comprising:

[0030] The active components are loaded onto a support, wherein the active components are Ni and Cu; wherein the molar ratio of Ni to Cu is 0.5-10:1, preferably 5-10:1.

[0031] In some embodiments of the present invention, the amount of the active component is such that, based on the total weight of the catalyst, the content of the active component, calculated as metal element, is 10-70% by weight, preferably 30-60% by weight.

[0032] In some embodiments of the present invention, to prevent copper microcrystal sintering, promote copper dispersion, and improve catalyst stability, the method further includes loading a first additive and / or a second additive onto the support, wherein the first additive and the second additive are selected from different transition metals. The first additive includes W and / or Mo; the second additive includes Fe and / or Co.

[0033] In some embodiments of the present invention, the amounts of the active component, the first auxiliary agent, and the second auxiliary agent are such that, based on the total weight of the catalyst, the content of the active component, calculated in terms of metal elements, is 10-70% by weight, preferably 30-60% by weight; the content of the first auxiliary agent, calculated in terms of metal elements, is 0-5% by weight, preferably 1-2% by weight; the content of the second auxiliary agent, calculated in terms of metal elements, is 0-5% by weight, preferably 0.5-2% by weight; and the remainder is a carrier.

[0034] In some embodiments of the present invention, in order to uniformly disperse the high-content active components and auxiliary components on the carrier, the loading method is as follows:

[0035] The active component precursor solution, precipitant solution, and optional auxiliary agent precursor solution are added to a suspension containing a support for precipitation. During the precipitation process, the addition rate is controlled to maintain the pH value of the system at 9-10. Then, solid-liquid separation, drying, and calcination are performed sequentially to obtain the catalyst.

[0036] In some embodiments of the present invention, the molar concentration of the nickel precursor, calculated as Ni, in the active component precursor solution is 0.2-1.05 mol / L, preferably 0.6-0.9 mol / L, and the molar concentration of the copper precursor, calculated as Cu, is 0.01-0.6 mol / L, preferably 0.08-0.12 mol / L.

[0037] In some embodiments of the present invention, the molar concentration of the auxiliary agent precursor in the first auxiliary agent precursor solution, calculated as a metal element, is 0.01-0.05 mol / L. The molar concentration of the auxiliary agent precursor in the second auxiliary agent precursor solution, calculated as a metal element, is 0.01-0.05 mol / L.

[0038] In some embodiments of the present invention, the molar concentration of the precipitant in the precipitant solution is 1.2-2.5 mol / L, preferably 1.5-2 mol / L.

[0039] In some embodiments of the present invention, in order to ensure that the active components and auxiliary components are uniformly loaded onto the carrier, the solid-liquid ratio of the carrier to water in the carrier-containing suspension is 4-8 g: 100 mL.

[0040] In some embodiments of the present invention, in order to enable the active component and the auxiliary component to undergo a uniform and controllable chemical reaction with the precipitant, the active component precursor solution, the optional first auxiliary component precursor solution, the optional second auxiliary component precursor solution, and the precipitant solution are added in parallel to the suspension containing the carrier.

[0041] In some embodiments of the present invention, in order to control the rate of formation of the active component metal precipitate, so that the generated precipitate microcrystals are small, the addition rate of the active component precursor solution is 1-5 mL / min relative to 10 g of carrier.

[0042] In some embodiments of the present invention, in order to control the rate of metal precipitation of the auxiliary component so that the generated precipitate crystals are small, the addition rate of the auxiliary precursor solution is 1-5 mL / min relative to 10 g of carrier.

[0043] In some embodiments of the present invention, in order to control the rate of precipitation of each metal component and the pH of the mother liquor, the addition rate of the precipitant solution is 1-5 mL / min relative to 10 g of carrier.

[0044] In some embodiments of the present invention, the support is selected from alumina and / or silicon oxide, preferably γ-Al2O3.

[0045] In some embodiments of the present invention, the specific type of nickel precursor is not limited. For example, the nickel precursor is a water-soluble nickel salt, preferably selected from at least one of nickel nitrate, nickel chloride, and nickel sulfate, and more preferably nickel nitrate. The specific type of copper precursor is not limited. For example, the copper precursor is a water-soluble copper salt, preferably selected from at least one of copper nitrate, copper chloride, and copper acetate, and more preferably copper nitrate.

[0046] In some embodiments of the present invention, the specific type of the auxiliary agent precursor is not particularly limited, as long as it is a water-soluble salt. For example, the first auxiliary agent precursor is an ammonium salt; the second auxiliary agent precursor is selected from at least one of nitrate, carbonate and acetate.

[0047] In some embodiments of the present invention, the precipitant is a substance capable of precipitating the metal ions of the active component and the metal ions of the auxiliaries. Preferably, the precipitant includes potassium salts and / or sodium salts, and is preferably selected from at least one of sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium carbonate, potassium bicarbonate, and potassium hydroxide.

[0048] In some embodiments of the present invention, the precipitation temperature is preferably 40-80°C.

[0049] In some embodiments of the present invention, to ensure the formation of precipitated crystals and their uniform particle size distribution, the loading method further includes aging the precipitate system before solid-liquid separation after the complete precipitation step. In this invention, aging refers to isothermal aging.

[0050] In some embodiments of the present invention, the aging temperature is preferably 40-80°C, and the time is preferably 4-8 hours. The drying temperature is preferably 100-120°C, and the time is preferably 6-12 hours. The calcination temperature is preferably 300-500°C, and the time is preferably 2-8 hours.

[0051] In this invention, the method may further include a step of shaping the obtained catalyst. There are no restrictions on the shaping method; conventional tableting can be used.

[0052] The catalyst of this invention can be used after grinding and sieving or after molding. Preferably, the particle size of the catalyst is 10-20 mesh for laboratory use and 3-5 mm in diameter for industrial use.

[0053] A third aspect of the present invention provides a catalyst prepared by the method described above.

[0054] A fourth aspect of the present invention provides a method for hydrogenating and refining a recovered solvent in an olefin epoxidation reaction, the method comprising:

[0055] (1) In a hydrogen atmosphere, the recovered solvent from the olefin epoxidation reaction is brought into contact with the catalyst;

[0056] (2) Optionally, the effluent obtained after contact in step (1) can be used as a solvent for the olefin epoxidation reaction;

[0057] The catalyst in step (1) refers to the catalyst mentioned above.

[0058] In this invention, the active component of the catalyst exists in an oxidized state, therefore it needs to be reduced before contacting the recovered solvent from the olefin epoxidation reaction. Specifically, the catalyst is reduced in a hydrogen atmosphere. The reduction conditions include: a temperature preferably of 300-450°C, a pressure preferably of 0.5-5 MPa, and a time preferably of 4-10 h.

[0059] In some embodiments of the present invention, the contact conditions include: a temperature preferably of 60-140°C, a pressure preferably of 0.5-5 MPa, a volume ratio of hydrogen to recovered solvent preferably of 5-200:1, and a liquid hourly space velocity of 1-10 h⁻¹. -1 .

[0060] The recovered solvent from the olefin epoxidation reaction contains impurities such as ketones, esters, and ethers. For example, in the method of directly oxidizing propylene to produce propylene oxide using hydrogen peroxide as a raw material, the olefin epoxidation reaction produces impurities such as dimethoxyethane (0.02-0.05 wt%), acetaldehyde (0.005-0.02 wt%), methanol (93-95 wt%), 1-propanediol monomethyl ether (0.02-0.05 wt%), 2-propanediol monomethyl ether (0.01-0.03 wt%), propionaldehyde (0.005-0.02 wt%), acetone (0.01-0.02 wt%), monoether (0.05-0.08 wt%), and ethanol (0.1-0.3 wt%).

[0061] In this invention, the hydrogenation purification process of the recovered solvent in the olefin epoxidation reaction can be carried out in a manner such as... Figure 1The reaction is carried out in the apparatus shown. Specifically, the recovered solvent is fed into the reaction system through the inlet of the conveying device 100. The outlet of the conveying device 100 is connected to the first heat exchange device 200, which can preheat the recovered solvent. The first heat exchange device 200 is connected to the second heat exchange device 300, which is connected to the mixing device 400. The mixing device 400 is provided with a hydrogen inlet. The mixing device 400 is connected to the inlet of the reaction device 500. The reaction device 500 is filled with the catalyst of the present invention, and both ends of the catalyst are filled with inert ceramic balls. The second heat exchanger can further heat and recover the solvent, and after heating to the required reaction temperature, it is mixed with hydrogen in the mixing device 400 and then enters the reaction device 500 to participate in the reaction. The outlet of the reaction device 500 is connected to the first heat exchanger 200, which is used to heat and recover the solvent using the output of the reaction device 500, thereby realizing the recycling of energy. The third heat exchanger 600 is connected to the first heat exchanger 100. The third heat exchanger 600 is used to cool the output of the reaction device 500 again. The outlet of the third heat exchanger 600 is connected to the separation device 700. The top of the separation device 700 discharges residual hydrogen and discharges it to a water washing tower (not shown). After absorbing and removing methanol, it is discharged to a hydrogen-containing flare or recycled by a circulating compressor. The liquid phase at the bottom of the separation device 700 is recycled.

[0062] The present invention will be described in detail below through embodiments.

[0063] Example 1

[0064] (1) Dissolve 50.14 g of Ni(NO3)2·6H2O and 3.25 g of Cu(NO3)2 in deionized water to prepare a 200 mL active component precursor solution; dissolve 11.96 g of Na2CO3 and 9.02 g of NaOH in deionized water to prepare a 200 mL precipitant solution. Disperse 12.86 g of alumina dry adhesive powder in 200 mL of deionized water and place it in a precipitation tank.

[0065] (2) The active component precursor solution and the precipitant were titrated at a constant rate to a precipitation tank at 60°C under rapid stirring conditions using a co-current method. The addition rate of the active component precursor solution was 3 mL / min, and the addition rate of the precipitant solution was 3 mL / min. The pH value was maintained at 9-10. After precipitation, the precipitate was aged at 60°C for 6 hours. The aged precipitate was filtered and washed several times with deionized water until the pH was neutral. It was then vacuum filtered, and the resulting filter cake was dried in a 120°C forced-air drying oven for 12 hours. Then, it was calcined in a muffle furnace at 400°C for 6 hours. After calcination, the catalyst was ground into powder, pressed into tablets, crushed, and sieved to obtain a 10-20 mesh catalyst.

[0066] Take 5 grams of the obtained catalyst and load it into a fixed-bed stainless steel reactor with a diameter of 12 mm and a length of 90 cm. The upper and lower ends of the reactor are filled with quartz sand, and the middle is filled with the catalyst to ensure that the catalyst is in the constant temperature zone of the reactor (unless otherwise specified, the following examples all use this reactor and the filling method is the same). In this reactor, the catalyst is first reduced and then the solvent is recovered and purified by hydrogenation.

[0067] The catalyst reduction conditions include: a temperature of 400℃, a pressure of 0.5MPa, a reduction atmosphere of pure hydrogen, and a reduction time of 10h.

[0068] The hydrorefining conditions were: temperature 120℃, pressure 1.5MPa, hydrogen to alcohol solvent volume ratio 50:1, and alcohol solvent liquid hourly space velocity 5h⁻¹. -1 The composition of the recovered solvent before and after the hydrogenation reaction is shown in Table 2-5.

[0069] refer to Figure 1 Hydrogenation refining of recovered solvents Figure 1 The reaction is carried out on the apparatus shown. The recovered solvent is pumped to a pressure of 2.0 MPa via conveyor 100, then heated to the required reaction temperature of 100°C via first heat exchanger 200 and second heat exchanger 300. After mixing with hydrogen in mixing equipment 400, the mixture enters reaction equipment 500 from the top. Hydrogen is the continuous phase. After the reaction, the material is conveyed to product separation equipment 700 via first heat exchanger 200 and third heat exchanger 600. The hydrogen at the top of separation equipment 700 is discharged to a water washing tower (not shown). After methanol is removed by absorption, the hydrogen is discharged to a hydrogen-containing flare or recycled via a circulating compressor. The alcohol solvent at the bottom of separation equipment 700 is pumped to the previous unit for recycling.

[0070] Example 2

[0071] The catalyst was prepared according to the method of Example 1, except that step (1) was replaced by: dissolving 30.08 g of Ni(NO3)2·6H2O and 5.86 g of Cu(NO3)2 in deionized water to prepare a 200 mL active component precursor solution; dissolving 8.56 g of Na2CO3 and 6.46 g of NaOH in deionized water to prepare a 200 mL precipitant solution; and dispersing 17.14 g of alumina dry adhesive powder in 200 mL of deionized water in a precipitation tank.

[0072] Example 3

[0073] The catalyst was prepared according to the method of Example 1, except that step (1) was replaced by: dissolving 32 g of NiCl2·6H2O and 4.99 g of Cu(CH3COO)2·H2O in deionized water to prepare a 200 mL active component precursor solution; dissolving 16.42 g of NaHCO3 and 7.82 g of NaOH in deionized water to prepare a 200 mL precipitant solution; and dispersing 14.86 g of alumina dry adhesive powder in 200 mL of deionized water in a precipitation tank.

[0074] Example 4

[0075] The catalyst was prepared according to the method of Example 1, except that step (1) was replaced by: dissolving 16.2 g of NiCl2·6H2O and 16.11 g of CuCl2·2H2O in deionized water to prepare a 200 mL active component precursor solution; dissolving 16.4 g of NaHCO3 and 7.8 g of NaOH in deionized water to prepare a 200 mL precipitant solution. Dispersing 10 g of alumina dry adhesive powder in 200 mL of deionized water in a precipitation tank.

[0076] Example 5

[0077] The catalyst was prepared according to the method of Example 1, except that in step (2), the precipitation and aging temperatures were both 40°C.

[0078] Example 6

[0079] The catalyst was prepared according to the method of Example 1, except that in step (2), the precipitation and aging temperatures were both 80°C.

[0080] Example 7

[0081] The catalyst was prepared according to the method of Example 1, except that in step (2), the calcination temperature was 300°C.

[0082] Example 8

[0083] The catalyst was prepared according to the method of Example 1, except that in step (2), the calcination temperature was 500°C.

[0084] Example 9

[0085] The catalyst was prepared according to the method of Example 1, except that in step (1), 1.84 g of ammonium heptamolybdate was dissolved in deionized water to prepare 100 mL of auxiliary precursor solution, and 0.31 g of cobalt nitrate, the second auxiliary agent, was added to the active component precursor solution; and in step (2), the addition rate of the auxiliary precursor solution was 1.5 mL / min.

[0086] Example 10

[0087] The catalyst was prepared according to the method of Example 1, except that in step (1), 0.92 g of ammonium heptamolybdate was dissolved in deionized water to prepare 100 mL of auxiliary agent precursor solution; 0.86 g of the second auxiliary agent ferric nitrate was added to the active component precursor solution; and in step (2), the addition rate of the auxiliary agent precursor solution was 1.5 mL / min.

[0088] Example 11

[0089] The catalyst obtained in Example 1 was used to hydrogenate the recovered solvent from the olefin epoxidation reaction in the same manner as in Example 1, except that the hydrogenation conditions were: temperature 60°C, pressure 0.5 MPa, hydrogen to alcohol solvent volume ratio 200:1, and liquid hourly space velocity 1 h⁻¹. -1 .

[0090] Example 12

[0091] The catalyst obtained in Example 1 was used to hydrogenate the recovered solvent from the olefin epoxidation reaction, following the method described in Test Example 1. The difference was that the hydrogenation purification conditions were: temperature 140°C, pressure 5 MPa, hydrogen to alcohol solvent volume ratio 5:1, and liquid hourly space velocity 10 h⁻¹. -1 .

[0092] Example 13

[0093] Following the method described in Test Example 1, the catalyst obtained in Example 1 was used to hydrogenate the recovered solvent from the olefin epoxidation reaction. The difference was that the hydrogenation purification conditions were: temperature 100°C, pressure 2 MPa, hydrogen to alcohol solvent volume ratio 60:1, and liquid hourly space velocity 4 h⁻¹. -1 .

[0094] Example 14

[0095] The catalyst was prepared according to the method of Example 1, except that in step (1), 1.16 g of zinc nitrate was dissolved in deionized water to prepare 100 mL of auxiliary agent precursor solution; and in step (2), the addition rate of auxiliary agent precursor solution was 1.5 mL / min.

[0096] Example 15

[0097] The catalyst was prepared according to the method of Example 9, except that in step (1), cobalt nitrate was replaced with ammonium heptamolybdate.

[0098] Comparative Example 1

[0099] The catalyst was prepared according to the method of Example 1, except that in step (1), Cu(NO3)2 was replaced with Ni(NO3)2·6H2O.

[0100] Comparative Example 2

[0101] The catalyst was prepared according to the method of Example 1, except that in step (1), Ni(NO3)2·6H2O was replaced with Cu(NO3)2.

[0102] Comparative Example 3

[0103] The catalyst was prepared according to the method of Example 1, except that in step (1), Cu(NO3)2 was replaced with an equal weight of Mg(NO3)2.

[0104] Comparative Example 4

[0105] The catalyst was prepared according to the method of Example 1, except that in step (1), the amount of Cu(NO3)2 used was 0.5g.

[0106] Test Example 1

[0107] In the examples and comparative examples, the pore volume, average pore diameter, and specific surface area of ​​the catalysts were determined using a low-temperature nitrogen adsorption instrument, model Micromeritics ASAP2460. The test method was in accordance with GB / T5816-1995. The results of the pore volume, average pore diameter, and specific surface area of ​​the catalysts obtained are shown in Table 1.

[0108] The elemental content of the catalysts obtained in the examples and comparative examples was determined using an X-ray fluorescence spectrometer (Axiosmax). The test method followed enterprise standard Q / KJKF 97-2009, and the results are shown in Table 1.

[0109] Table 1

[0110]

[0111] Table 2

[0112]

[0113] Table 3

[0114]

[0115] Table 4

[0116]

[0117] Table 5

[0118]

[0119] As can be seen from the results in Tables 2-5, the embodiments employing the technical solution of this invention, using a nickel-copper catalyst to catalyze the hydrogenation purification of the recovered solvent from the olefin epoxidation reaction, achieve a 100% removal rate of acetaldehyde and a 76% removal rate of dimethoxyethane. Simultaneously, it saves 16% of the original steam energy consumption and 65% of the original solvent consumption. Furthermore, the content of the key impurity methylal in the propylene oxide product can be reduced by approximately 40%. In contrast, the comparative treatment resulted in lower removal rates of acetaldehyde and dimethoxyethane.

[0120] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for recovering solvent and hydrogenating it during an olefin epoxidation reaction, characterized in that, The method includes: (1) In a hydrogen atmosphere, the recovered solvent from the olefin epoxidation reaction is brought into contact with the catalyst; (2) Optionally, the effluent obtained after contact in step (1) can be used as a solvent for the olefin epoxidation reaction; The catalyst comprises a support and an active component supported on the support, the active component being Ni and Cu; the catalyst further comprises a first promoter and a second promoter supported on the support, the first promoter comprising W and / or Mo; the second promoter comprising Fe and / or Co; the support being selected from alumina; based on the total weight of the catalyst, the content of the active component, calculated by metal element, is 10-70% by weight; the content of the first promoter, calculated by metal element, is 1-2% by weight; the content of the second promoter, calculated by metal element, is 0.5-2% by weight; the remainder is the support; In the catalyst, the molar ratio of Ni to Cu is 5-10:

1.

2. The method according to claim 1, wherein, The catalyst has a specific surface area of ​​80-200 m². 2 / g; And / or, the catalyst has a pore volume of 0.2-0.6 cm³. 3 / g; And / or, the average pore size of the catalyst is 2-10 nm.

3. The method according to claim 1, wherein, Based on the total weight of the catalyst, the content of the active component, calculated as metal element, is 30-60% by weight.

4. The method according to claim 2, wherein, The catalyst has a specific surface area of ​​120-170 m². 2 / g.

5. The method according to claim 2, wherein, The catalyst has a pore volume of 0.25-0.5 cm³. 3 / g.

6. The method according to claim 2, wherein, The catalyst has an average pore size of 4-8 nm.

7. The method according to claim 1, wherein, The support is selected from γ-Al2O3.

8. The method according to claim 1, wherein, Based on the total weight of the catalyst, the content of the active component, calculated as metal element, is 30-60% by weight; the content of the first auxiliary agent, calculated as metal element, is 1-2% by weight; the content of the second auxiliary agent, calculated as metal element, is 0.5-2% by weight; and the remainder is the carrier.

9. The method according to claim 1, wherein, The method for preparing the catalyst includes: The active components are loaded onto a support, wherein the active components are Ni and Cu; wherein the molar ratio of Ni to Cu is 5-10:1; the method further includes loading a first auxiliary agent and a second auxiliary agent onto the support.

10. The method according to claim 9, wherein the loading method is: The active component precursor solution, precipitant solution, first auxiliary agent precursor solution, and second auxiliary agent precursor solution were added to a suspension containing a support for precipitation. During the precipitation process, the addition rate was controlled to keep the pH of the system at 9-10. Then, solid-liquid separation, drying, and calcination were carried out sequentially to obtain the catalyst.

11. The method according to claim 10, wherein, In the active component precursor solution, the molar concentration of nickel precursor (calculated as Ni) is 0.2-1.05 mol / L, and the molar concentration of copper precursor (calculated as Cu) is 0.01-0.6 mol / L. And / or, in the first auxiliary agent precursor solution, the molar concentration of the first auxiliary agent precursor, calculated as metal element, is 0.01-0.05 mol / L; And / or, in the second auxiliary agent precursor solution, the molar concentration of the second auxiliary agent precursor, calculated as a metal element, is 0.01-0.05 mol / L. And / or, in the precipitant solution, the molar concentration of the precipitant is 1.2-2.5 mol / L; And / or, in the carrier-containing suspension, the solid-liquid ratio of the carrier to water is 4-8 g: 100 mL; And / or, the active ingredient precursor solution, the first adjuvant precursor solution, the second adjuvant precursor solution, and the precipitant solution are added in parallel to the suspension containing the carrier; And / or, relative to 10g of carrier, the addition rate of the active component precursor solution is 1-5mL / min; And / or, relative to 10g of carrier, the addition rate of the auxiliary precursor solution is 1-5mL / min; And / or, relative to 10g of carrier, the addition rate of the precipitant solution is 1-5 mL / min.

12. The method according to claim 11, wherein the nickel precursor is a water-soluble nickel salt and the copper precursor is a water-soluble copper salt; And / or, the first auxiliary agent precursor is a water-soluble salt of the first auxiliary agent, and the second auxiliary agent precursor is a water-soluble salt of the second auxiliary agent; And / or, the precipitant includes potassium salts and / or sodium salts.

13. The method according to claim 11, wherein, The support is selected from γ-Al2O3.

14. The method according to claim 12, wherein, The nickel precursor is selected from at least one of nickel nitrate, nickel chloride, and nickel sulfate.

15. The method according to claim 14, wherein, The nickel precursor is nickel nitrate.

16. The method according to claim 12, wherein, The copper precursor is selected from at least one of copper nitrate, copper chloride, and copper acetate.

17. The method according to claim 16, wherein, The copper precursor is copper nitrate.

18. The method according to claim 12, wherein, The first auxiliary agent precursor is an ammonium salt; the second auxiliary agent precursor is selected from at least one of nitrate and acetate.

19. The method according to claim 12, wherein, The precipitant is selected from at least one of sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium carbonate, potassium bicarbonate, and potassium hydroxide.

20. The method of claim 10, wherein, The precipitation temperature is 40-80℃; And / or, the loading method further includes: aging the precipitation system before solid-liquid separation after the precipitation step is completed; the aging temperature is 40-80℃ and the time is 4-8h; And / or, the drying temperature is 100-120℃ and the time is 6-12h; And / or, the calcination temperature is 300-500℃ and the time is 2-8h.

21. The method according to claim 1, characterized in that, The contact conditions include: a temperature of 60-140℃, a pressure of 0.5-5MPa, a hydrogen to recycled solvent volume ratio of 5-200:1, and a liquid hourly space velocity of 1-10h. -1 .

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